i2c-core-base.c source code [linux/drivers/i2c/i2c-core-base.c]

1	// SPDX-License-Identifier: GPL-2.0-or-later
2	/*
3	* Linux I2C core
4	*
5	* Copyright (C) 1995-99 Simon G. Vogl
6	* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi>
7	* Mux support by Rodolfo Giometti <giometti@enneenne.com> and
8	* Michael Lawnick <michael.lawnick.ext@nsn.com>
9	*
10	* Copyright (C) 2013-2017 Wolfram Sang <wsa@kernel.org>
11	*/
12
13	#define pr_fmt(fmt) "i2c-core: " fmt
14
15	#include <dt-bindings/i2c/i2c.h>
16	#include <linux/acpi.h>
17	#include <linux/clk/clk-conf.h>
18	#include <linux/completion.h>
19	#include <linux/debugfs.h>
20	#include <linux/delay.h>
21	#include <linux/err.h>
22	#include <linux/errno.h>
23	#include <linux/gpio/consumer.h>
24	#include <linux/i2c.h>
25	#include <linux/i2c-smbus.h>
26	#include <linux/idr.h>
27	#include <linux/init.h>
28	#include <linux/interrupt.h>
29	#include <linux/irqflags.h>
30	#include <linux/jump_label.h>
31	#include <linux/kernel.h>
32	#include <linux/module.h>
33	#include <linux/mutex.h>
34	#include <linux/of_device.h>
35	#include <linux/of.h>
36	#include <linux/of_irq.h>
37	#include <linux/pinctrl/consumer.h>
38	#include <linux/pinctrl/devinfo.h>
39	#include <linux/pm_domain.h>
40	#include <linux/pm_runtime.h>
41	#include <linux/pm_wakeirq.h>
42	#include <linux/property.h>
43	#include <linux/rwsem.h>
44	#include <linux/slab.h>
45
46	#include "i2c-core.h"
47
48	#define CREATE_TRACE_POINTS
49	#include <trace/events/i2c.h>
50
51	#define I2C_ADDR_OFFSET_TEN_BIT 0xa000
52	#define I2C_ADDR_OFFSET_SLAVE 0x1000
53
54	#define I2C_ADDR_7BITS_MAX 0x77
55	#define I2C_ADDR_7BITS_COUNT (I2C_ADDR_7BITS_MAX + 1)
56
57	#define I2C_ADDR_DEVICE_ID 0x7c
58
59	/*
60	* core_lock protects i2c_adapter_idr, and guarantees that device detection,
61	* deletion of detected devices are serialized
62	*/
63	static DEFINE_MUTEX(core_lock);
64	static DEFINE_IDR(i2c_adapter_idr);
65
66	static int i2c_detect(struct i2c_adapter adapter, struct* i2c_driver *driver);
67
68	static DEFINE_STATIC_KEY_FALSE(i2c_trace_msg_key);
69	static bool is_registered;
70
71	static struct dentry *i2c_debugfs_root;
72
73	int i2c_transfer_trace_reg(void)
74	{
75	static_branch_inc(&i2c_trace_msg_key);
76	return `0`;
77	}
78
79	void i2c_transfer_trace_unreg(void)
80	{
81	static_branch_dec(&i2c_trace_msg_key);
82	}
83
84	const char *i2c_freq_mode_string(u32 bus_freq_hz)
85	{
86	switch (bus_freq_hz) {
87	case I2C_MAX_STANDARD_MODE_FREQ:
88	return "Standard Mode (100 kHz)";
89	case I2C_MAX_FAST_MODE_FREQ:
90	return "Fast Mode (400 kHz)";
91	case I2C_MAX_FAST_MODE_PLUS_FREQ:
92	return "Fast Mode Plus (1.0 MHz)";
93	case I2C_MAX_TURBO_MODE_FREQ:
94	return "Turbo Mode (1.4 MHz)";
95	case I2C_MAX_HIGH_SPEED_MODE_FREQ:
96	return "High Speed Mode (3.4 MHz)";
97	case I2C_MAX_ULTRA_FAST_MODE_FREQ:
98	return "Ultra Fast Mode (5.0 MHz)";
99	default:
100	return "Unknown Mode";
101	}
102	}
103	EXPORT_SYMBOL_GPL(i2c_freq_mode_string);
104
105	const struct i2c_device_id i2c_match_id(const* struct i2c_device_id *id,
106	const struct i2c_client *client)
107	{
108	if (!(id && client))
109	return NULL;
110
111	while (id->name[`0`]) {
112	if (strcmp(client->name, id->name) == `0`)
113	return id;
114	id++;
115	}
116	return NULL;
117	}
118	EXPORT_SYMBOL_GPL(i2c_match_id);
119
120	const void i2c_get_match_data(const* struct i2c_client *client)
121	{
122	struct i2c_driver *driver = to_i2c_driver(client->dev.driver);
123	const struct i2c_device_id *match;
124	const void *data;
125
126	data = device_get_match_data(dev: &client->dev);
127	if (!data) {
128	match = i2c_match_id(driver->id_table, client);
129	if (!match)
130	return NULL;
131
132	data = (const void *)match->driver_data;
133	}
134
135	return data;
136	}
137	EXPORT_SYMBOL(i2c_get_match_data);
138
139	static int i2c_device_match(struct device dev, struct* device_driver *drv)
140	{
141	struct i2c_client *client = i2c_verify_client(dev);
142	struct i2c_driver *driver;
143
144
145	/ Attempt an OF style match /
146	if (i2c_of_match_device(matches: drv->of_match_table, client))
147	return `1`;
148
149	/ Then ACPI style match /
150	if (acpi_driver_match_device(dev, drv))
151	return `1`;
152
153	driver = to_i2c_driver(drv);
154
155	/ Finally an I2C match /
156	if (i2c_match_id(driver->id_table, client))
157	return `1`;
158
159	return `0`;
160	}
161
162	static int i2c_device_uevent(const struct device dev, struct* kobj_uevent_env *env)
163	{
164	const struct i2c_client *client = to_i2c_client(dev);
165	int rc;
166
167	rc = of_device_uevent_modalias(dev, env);
168	if (rc != -ENODEV)
169	return rc;
170
171	rc = acpi_device_uevent_modalias(dev, env);
172	if (rc != -ENODEV)
173	return rc;
174
175	return add_uevent_var(env, format: "MODALIAS=%s%s", I2C_MODULE_PREFIX, client->name);
176	}
177
178	/ i2c bus recovery routines /
179	static int get_scl_gpio_value(struct i2c_adapter *adap)
180	{
181	return gpiod_get_value_cansleep(desc: adap->bus_recovery_info->scl_gpiod);
182	}
183
184	static void set_scl_gpio_value(struct i2c_adapter adap, int* val)
185	{
186	gpiod_set_value_cansleep(desc: adap->bus_recovery_info->scl_gpiod, value: val);
187	}
188
189	static int get_sda_gpio_value(struct i2c_adapter *adap)
190	{
191	return gpiod_get_value_cansleep(desc: adap->bus_recovery_info->sda_gpiod);
192	}
193
194	static void set_sda_gpio_value(struct i2c_adapter adap, int* val)
195	{
196	gpiod_set_value_cansleep(desc: adap->bus_recovery_info->sda_gpiod, value: val);
197	}
198
199	static int i2c_generic_bus_free(struct i2c_adapter *adap)
200	{
201	struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
202	int ret = -EOPNOTSUPP;
203
204	if (bri->get_bus_free)
205	ret = bri->get_bus_free(adap);
206	else if (bri->get_sda)
207	ret = bri->get_sda(adap);
208
209	if (ret < `0`)
210	return ret;
211
212	return ret ? `0` : -EBUSY;
213	}
214
215	/*
216	* We are generating clock pulses. ndelay() determines durating of clk pulses.
217	* We will generate clock with rate 100 KHz and so duration of both clock levels
218	* is: delay in ns = (10^6 / 100) / 2
219	*/
220	#define RECOVERY_NDELAY 5000
221	#define RECOVERY_CLK_CNT 9
222
223	int i2c_generic_scl_recovery(struct i2c_adapter *adap)
224	{
225	struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
226	int i = `0`, scl = `1`, ret = `0`;
227
228	if (bri->prepare_recovery)
229	bri->prepare_recovery(adap);
230	if (bri->pinctrl)
231	pinctrl_select_state(p: bri->pinctrl, s: bri->pins_gpio);
232
233	/*
234	* If we can set SDA, we will always create a STOP to ensure additional
235	* pulses will do no harm. This is achieved by letting SDA follow SCL
236	* half a cycle later. Check the 'incomplete_write_byte' fault injector
237	* for details. Note that we must honour tsu:sto, 4us, but lets use 5us
238	* here for simplicity.
239	*/
240	bri->set_scl(adap, scl);
241	ndelay(RECOVERY_NDELAY);
242	if (bri->set_sda)
243	bri->set_sda(adap, scl);
244	ndelay(RECOVERY_NDELAY / `2`);
245
246	/*
247	* By this time SCL is high, as we need to give 9 falling-rising edges
248	*/
249	while (i++ < RECOVERY_CLK_CNT * `2`) {
250	if (scl) {
251	/ SCL shouldn't be low here /
252	if (!bri->get_scl(adap)) {
253	dev_err(&adap->dev,
254	"SCL is stuck low, exit recovery\n");
255	ret = -EBUSY;
256	break;
257	}
258	}
259
260	scl = !scl;
261	bri->set_scl(adap, scl);
262	/ Creating STOP again, see above /
263	if (scl) {
264	/ Honour minimum tsu:sto /
265	ndelay(RECOVERY_NDELAY);
266	} else {
267	/ Honour minimum tf and thd:dat /
268	ndelay(RECOVERY_NDELAY / `2`);
269	}
270	if (bri->set_sda)
271	bri->set_sda(adap, scl);
272	ndelay(RECOVERY_NDELAY / `2`);
273
274	if (scl) {
275	ret = i2c_generic_bus_free(adap);
276	if (ret == `0`)
277	break;
278	}
279	}
280
281	/ If we can't check bus status, assume recovery worked /
282	if (ret == -EOPNOTSUPP)
283	ret = `0`;
284
285	if (bri->unprepare_recovery)
286	bri->unprepare_recovery(adap);
287	if (bri->pinctrl)
288	pinctrl_select_state(p: bri->pinctrl, s: bri->pins_default);
289
290	return ret;
291	}
292	EXPORT_SYMBOL_GPL(i2c_generic_scl_recovery);
293
294	int i2c_recover_bus(struct i2c_adapter *adap)
295	{
296	if (!adap->bus_recovery_info)
297	return -EBUSY;
298
299	dev_dbg(&adap->dev, "Trying i2c bus recovery\n");
300	return adap->bus_recovery_info->recover_bus(adap);
301	}
302	EXPORT_SYMBOL_GPL(i2c_recover_bus);
303
304	static void i2c_gpio_init_pinctrl_recovery(struct i2c_adapter *adap)
305	{
306	struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
307	struct device *dev = &adap->dev;
308	struct pinctrl *p = bri->pinctrl ?: dev_pinctrl(dev: dev->parent);
309
310	bri->pinctrl = p;
311
312	/*
313	* we can't change states without pinctrl, so remove the states if
314	* populated
315	*/
316	if (!p) {
317	bri->pins_default = NULL;
318	bri->pins_gpio = NULL;
319	return;
320	}
321
322	if (!bri->pins_default) {
323	bri->pins_default = pinctrl_lookup_state(p,
324	PINCTRL_STATE_DEFAULT);
325	if (IS_ERR(ptr: bri->pins_default)) {
326	dev_dbg(dev, PINCTRL_STATE_DEFAULT " state not found for GPIO recovery\n");
327	bri->pins_default = NULL;
328	}
329	}
330	if (!bri->pins_gpio) {
331	bri->pins_gpio = pinctrl_lookup_state(p, name: "gpio");
332	if (IS_ERR(ptr: bri->pins_gpio))
333	bri->pins_gpio = pinctrl_lookup_state(p, name: "recovery");
334
335	if (IS_ERR(ptr: bri->pins_gpio)) {
336	dev_dbg(dev, "no gpio or recovery state found for GPIO recovery\n");
337	bri->pins_gpio = NULL;
338	}
339	}
340
341	/ for pinctrl state changes, we need all the information /
342	if (bri->pins_default && bri->pins_gpio) {
343	dev_info(dev, "using pinctrl states for GPIO recovery");
344	} else {
345	bri->pinctrl = NULL;
346	bri->pins_default = NULL;
347	bri->pins_gpio = NULL;
348	}
349	}
350
351	static int i2c_gpio_init_generic_recovery(struct i2c_adapter *adap)
352	{
353	struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
354	struct device *dev = &adap->dev;
355	struct gpio_desc *gpiod;
356	int ret = `0`;
357
358	/*
359	* don't touch the recovery information if the driver is not using
360	* generic SCL recovery
361	*/
362	if (bri->recover_bus && bri->recover_bus != i2c_generic_scl_recovery)
363	return `0`;
364
365	/*
366	* pins might be taken as GPIO, so we should inform pinctrl about
367	* this and move the state to GPIO
368	*/
369	if (bri->pinctrl)
370	pinctrl_select_state(p: bri->pinctrl, s: bri->pins_gpio);
371
372	/*
373	* if there is incomplete or no recovery information, see if generic
374	* GPIO recovery is available
375	*/
376	if (!bri->scl_gpiod) {
377	gpiod = devm_gpiod_get(dev, con_id: "scl", flags: GPIOD_OUT_HIGH_OPEN_DRAIN);
378	if (PTR_ERR(ptr: gpiod) == -EPROBE_DEFER) {
379	ret = -EPROBE_DEFER;
380	goto cleanup_pinctrl_state;
381	}
382	if (!IS_ERR(ptr: gpiod)) {
383	bri->scl_gpiod = gpiod;
384	bri->recover_bus = i2c_generic_scl_recovery;
385	dev_info(dev, "using generic GPIOs for recovery\n");
386	}
387	}
388
389	/ SDA GPIOD line is optional, so we care about DEFER only /
390	if (!bri->sda_gpiod) {
391	/*
392	* We have SCL. Pull SCL low and wait a bit so that SDA glitches
393	* have no effect.
394	*/
395	gpiod_direction_output(desc: bri->scl_gpiod, value: `0`);
396	udelay(`10`);
397	gpiod = devm_gpiod_get(dev, con_id: "sda", flags: GPIOD_IN);
398
399	/ Wait a bit in case of a SDA glitch, and then release SCL. /
400	udelay(`10`);
401	gpiod_direction_output(desc: bri->scl_gpiod, value: `1`);
402
403	if (PTR_ERR(ptr: gpiod) == -EPROBE_DEFER) {
404	ret = -EPROBE_DEFER;
405	goto cleanup_pinctrl_state;
406	}
407	if (!IS_ERR(ptr: gpiod))
408	bri->sda_gpiod = gpiod;
409	}
410
411	cleanup_pinctrl_state:
412	/ change the state of the pins back to their default state /
413	if (bri->pinctrl)
414	pinctrl_select_state(p: bri->pinctrl, s: bri->pins_default);
415
416	return ret;
417	}
418
419	static int i2c_gpio_init_recovery(struct i2c_adapter *adap)
420	{
421	i2c_gpio_init_pinctrl_recovery(adap);
422	return i2c_gpio_init_generic_recovery(adap);
423	}
424
425	static int i2c_init_recovery(struct i2c_adapter *adap)
426	{
427	struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
428	bool is_error_level = true;
429	char *err_str;
430
431	if (!bri)
432	return `0`;
433
434	if (i2c_gpio_init_recovery(adap) == -EPROBE_DEFER)
435	return -EPROBE_DEFER;
436
437	if (!bri->recover_bus) {
438	err_str = "no suitable method provided";
439	is_error_level = false;
440	goto err;
441	}
442
443	if (bri->scl_gpiod && bri->recover_bus == i2c_generic_scl_recovery) {
444	bri->get_scl = get_scl_gpio_value;
445	bri->set_scl = set_scl_gpio_value;
446	if (bri->sda_gpiod) {
447	bri->get_sda = get_sda_gpio_value;
448	/ FIXME: add proper flag instead of '0' once available /
449	if (gpiod_get_direction(desc: bri->sda_gpiod) == `0`)
450	bri->set_sda = set_sda_gpio_value;
451	}
452	} else if (bri->recover_bus == i2c_generic_scl_recovery) {
453	/ Generic SCL recovery /
454	if (!bri->set_scl \|\| !bri->get_scl) {
455	err_str = "no {get\|set}_scl() found";
456	goto err;
457	}
458	if (!bri->set_sda && !bri->get_sda) {
459	err_str = "either get_sda() or set_sda() needed";
460	goto err;
461	}
462	}
463
464	return `0`;
465	err:
466	if (is_error_level)
467	dev_err(&adap->dev, "Not using recovery: %s\n", err_str);
468	else
469	dev_dbg(&adap->dev, "Not using recovery: %s\n", err_str);
470	adap->bus_recovery_info = NULL;
471
472	return -EINVAL;
473	}
474
475	static int i2c_smbus_host_notify_to_irq(const struct i2c_client *client)
476	{
477	struct i2c_adapter *adap = client->adapter;
478	unsigned int irq;
479
480	if (!adap->host_notify_domain)
481	return -ENXIO;
482
483	if (client->flags & I2C_CLIENT_TEN)
484	return -EINVAL;
485
486	irq = irq_create_mapping(host: adap->host_notify_domain, hwirq: client->addr);
487
488	return irq > `0` ? irq : -ENXIO;
489	}
490
491	static int i2c_device_probe(struct device *dev)
492	{
493	struct i2c_client *client = i2c_verify_client(dev);
494	struct i2c_driver *driver;
495	bool do_power_on;
496	int status;
497
498	if (!client)
499	return `0`;
500
501	client->irq = client->init_irq;
502
503	if (!client->irq) {
504	int irq = -ENOENT;
505
506	if (client->flags & I2C_CLIENT_HOST_NOTIFY) {
507	dev_dbg(dev, "Using Host Notify IRQ\n");
508	/ Keep adapter active when Host Notify is required /
509	pm_runtime_get_sync(dev: &client->adapter->dev);
510	irq = i2c_smbus_host_notify_to_irq(client);
511	} else if (dev->of_node) {
512	irq = of_irq_get_byname(dev: dev->of_node, name: "irq");
513	if (irq == -EINVAL \|\| irq == -ENODATA)
514	irq = of_irq_get(dev: dev->of_node, index: `0`);
515	} else if (ACPI_COMPANION(dev)) {
516	bool wake_capable;
517
518	irq = i2c_acpi_get_irq(client, wake_capable: &wake_capable);
519	if (irq > `0` && wake_capable)
520	client->flags \|= I2C_CLIENT_WAKE;
521	}
522	if (irq == -EPROBE_DEFER) {
523	status = irq;
524	goto put_sync_adapter;
525	}
526
527	if (irq < `0`)
528	irq = `0`;
529
530	client->irq = irq;
531	}
532
533	driver = to_i2c_driver(dev->driver);
534
535	/*
536	* An I2C ID table is not mandatory, if and only if, a suitable OF
537	* or ACPI ID table is supplied for the probing device.
538	*/
539	if (!driver->id_table &&
540	!acpi_driver_match_device(dev, drv: dev->driver) &&
541	!i2c_of_match_device(matches: dev->driver->of_match_table, client)) {
542	status = -ENODEV;
543	goto put_sync_adapter;
544	}
545
546	if (client->flags & I2C_CLIENT_WAKE) {
547	int wakeirq;
548
549	wakeirq = of_irq_get_byname(dev: dev->of_node, name: "wakeup");
550	if (wakeirq == -EPROBE_DEFER) {
551	status = wakeirq;
552	goto put_sync_adapter;
553	}
554
555	device_init_wakeup(dev: &client->dev, enable: true);
556
557	if (wakeirq > `0` && wakeirq != client->irq)
558	status = dev_pm_set_dedicated_wake_irq(dev, irq: wakeirq);
559	else if (client->irq > `0`)
560	status = dev_pm_set_wake_irq(dev, irq: client->irq);
561	else
562	status = `0`;
563
564	if (status)
565	dev_warn(&client->dev, "failed to set up wakeup irq\n");
566	}
567
568	dev_dbg(dev, "probe\n");
569
570	status = of_clk_set_defaults(node: dev->of_node, clk_supplier: false);
571	if (status < `0`)
572	goto err_clear_wakeup_irq;
573
574	do_power_on = !i2c_acpi_waive_d0_probe(dev);
575	status = dev_pm_domain_attach(dev: &client->dev, power_on: do_power_on);
576	if (status)
577	goto err_clear_wakeup_irq;
578
579	client->devres_group_id = devres_open_group(dev: &client->dev, NULL,
580	GFP_KERNEL);
581	if (!client->devres_group_id) {
582	status = -ENOMEM;
583	goto err_detach_pm_domain;
584	}
585
586	if (driver->probe)
587	status = driver->probe(client);
588	else
589	status = -EINVAL;
590
591	/*
592	* Note that we are not closing the devres group opened above so
593	* even resources that were attached to the device after probe is
594	* run are released when i2c_device_remove() is executed. This is
595	* needed as some drivers would allocate additional resources,
596	* for example when updating firmware.
597	*/
598
599	if (status)
600	goto err_release_driver_resources;
601
602	return `0`;
603
604	err_release_driver_resources:
605	devres_release_group(dev: &client->dev, id: client->devres_group_id);
606	err_detach_pm_domain:
607	dev_pm_domain_detach(dev: &client->dev, power_off: do_power_on);
608	err_clear_wakeup_irq:
609	dev_pm_clear_wake_irq(dev: &client->dev);
610	device_init_wakeup(dev: &client->dev, enable: false);
611	put_sync_adapter:
612	if (client->flags & I2C_CLIENT_HOST_NOTIFY)
613	pm_runtime_put_sync(dev: &client->adapter->dev);
614
615	return status;
616	}
617
618	static void i2c_device_remove(struct device *dev)
619	{
620	struct i2c_client *client = to_i2c_client(dev);
621	struct i2c_driver *driver;
622
623	driver = to_i2c_driver(dev->driver);
624	if (driver->remove) {
625	dev_dbg(dev, "remove\n");
626
627	driver->remove(client);
628	}
629
630	devres_release_group(dev: &client->dev, id: client->devres_group_id);
631
632	dev_pm_domain_detach(dev: &client->dev, power_off: true);
633
634	dev_pm_clear_wake_irq(dev: &client->dev);
635	device_init_wakeup(dev: &client->dev, enable: false);
636
637	client->irq = `0`;
638	if (client->flags & I2C_CLIENT_HOST_NOTIFY)
639	pm_runtime_put(dev: &client->adapter->dev);
640	}
641
642	static void i2c_device_shutdown(struct device *dev)
643	{
644	struct i2c_client *client = i2c_verify_client(dev);
645	struct i2c_driver *driver;
646
647	if (!client \|\| !dev->driver)
648	return;
649	driver = to_i2c_driver(dev->driver);
650	if (driver->shutdown)
651	driver->shutdown(client);
652	else if (client->irq > `0`)
653	disable_irq(irq: client->irq);
654	}
655
656	static void i2c_client_dev_release(struct device *dev)
657	{
658	kfree(to_i2c_client(dev));
659	}
660
661	static ssize_t
662	name_show(struct device dev, struct* device_attribute attr, char* *buf)
663	{
664	return sprintf(buf, fmt: "%s\n", dev->type == &i2c_client_type ?
665	to_i2c_client(dev)->name : to_i2c_adapter(dev)->name);
666	}
667	static DEVICE_ATTR_RO(name);
668
669	static ssize_t
670	modalias_show(struct device dev, struct* device_attribute attr, char* *buf)
671	{
672	struct i2c_client *client = to_i2c_client(dev);
673	int len;
674
675	len = of_device_modalias(dev, str: buf, PAGE_SIZE);
676	if (len != -ENODEV)
677	return len;
678
679	len = acpi_device_modalias(dev, buf, PAGE_SIZE - `1`);
680	if (len != -ENODEV)
681	return len;
682
683	return sprintf(buf, fmt: "%s%s\n", I2C_MODULE_PREFIX, client->name);
684	}
685	static DEVICE_ATTR_RO(modalias);
686
687	static struct attribute *i2c_dev_attrs[] = {
688	&dev_attr_name.attr,
689	/ modalias helps coldplug: modprobe $(cat .../modalias) /
690	&dev_attr_modalias.attr,
691	NULL
692	};
693	ATTRIBUTE_GROUPS(i2c_dev);
694
695	const struct bus_type i2c_bus_type = {
696	.name = "i2c",
697	.match = i2c_device_match,
698	.probe = i2c_device_probe,
699	.remove = i2c_device_remove,
700	.shutdown = i2c_device_shutdown,
701	};
702	EXPORT_SYMBOL_GPL(i2c_bus_type);
703
704	const struct device_type i2c_client_type = {
705	.groups = i2c_dev_groups,
706	.uevent = i2c_device_uevent,
707	.release = i2c_client_dev_release,
708	};
709	EXPORT_SYMBOL_GPL(i2c_client_type);
710
711
712	/**
713	* i2c_verify_client - return parameter as i2c_client, or NULL
714	* @dev: device, probably from some driver model iterator
715	*
716	* When traversing the driver model tree, perhaps using driver model
717	* iterators like @device_for_each_child(), you can't assume very much
718	* about the nodes you find. Use this function to avoid oopses caused
719	* by wrongly treating some non-I2C device as an i2c_client.
720	*/
721	struct i2c_client i2c_verify_client(struct* device *dev)
722	{
723	return (dev->type == &i2c_client_type)
724	? to_i2c_client(dev)
725	: NULL;
726	}
727	EXPORT_SYMBOL(i2c_verify_client);
728
729
730	/ Return a unique address which takes the flags of the client into account /
731	static unsigned short i2c_encode_flags_to_addr(struct i2c_client *client)
732	{
733	unsigned short addr = client->addr;
734
735	/ For some client flags, add an arbitrary offset to avoid collisions /
736	if (client->flags & I2C_CLIENT_TEN)
737	addr \|= I2C_ADDR_OFFSET_TEN_BIT;
738
739	if (client->flags & I2C_CLIENT_SLAVE)
740	addr \|= I2C_ADDR_OFFSET_SLAVE;
741
742	return addr;
743	}
744
745	/ This is a permissive address validity check, I2C address map constraints*
746	* are purposely not enforced, except for the general call address. */
747	static int i2c_check_addr_validity(unsigned int addr, unsigned short flags)
748	{
749	if (flags & I2C_CLIENT_TEN) {
750	/ 10-bit address, all values are valid /
751	if (addr > `0x3ff`)
752	return -EINVAL;
753	} else {
754	/ 7-bit address, reject the general call address /
755	if (addr == `0x00` \|\| addr > `0x7f`)
756	return -EINVAL;
757	}
758	return `0`;
759	}
760
761	/ And this is a strict address validity check, used when probing. If a*
762	* device uses a reserved address, then it shouldn't be probed. 7-bit
763	* addressing is assumed, 10-bit address devices are rare and should be
764	* explicitly enumerated. */
765	int i2c_check_7bit_addr_validity_strict(unsigned short addr)
766	{
767	/*
768	* Reserved addresses per I2C specification:
769	* 0x00 General call address / START byte
770	* 0x01 CBUS address
771	* 0x02 Reserved for different bus format
772	* 0x03 Reserved for future purposes
773	* 0x04-0x07 Hs-mode master code
774	* 0x78-0x7b 10-bit slave addressing
775	* 0x7c-0x7f Reserved for future purposes
776	*/
777	if (addr < `0x08` \|\| addr > `0x77`)
778	return -EINVAL;
779	return `0`;
780	}
781
782	static int __i2c_check_addr_busy(struct device dev, void* *addrp)
783	{
784	struct i2c_client *client = i2c_verify_client(dev);
785	int addr = (int* *)addrp;
786
787	if (client && i2c_encode_flags_to_addr(client) == addr)
788	return -EBUSY;
789	return `0`;
790	}
791
792	/ walk up mux tree /
793	static int i2c_check_mux_parents(struct i2c_adapter adapter, int* addr)
794	{
795	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
796	int result;
797
798	result = device_for_each_child(dev: &adapter->dev, data: &addr,
799	fn: __i2c_check_addr_busy);
800
801	if (!result && parent)
802	result = i2c_check_mux_parents(adapter: parent, addr);
803
804	return result;
805	}
806
807	/ recurse down mux tree /
808	static int i2c_check_mux_children(struct device dev, void* *addrp)
809	{
810	int result;
811
812	if (dev->type == &i2c_adapter_type)
813	result = device_for_each_child(dev, data: addrp,
814	fn: i2c_check_mux_children);
815	else
816	result = __i2c_check_addr_busy(dev, addrp);
817
818	return result;
819	}
820
821	static int i2c_check_addr_busy(struct i2c_adapter adapter, int* addr)
822	{
823	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
824	int result = `0`;
825
826	if (parent)
827	result = i2c_check_mux_parents(adapter: parent, addr);
828
829	if (!result)
830	result = device_for_each_child(dev: &adapter->dev, data: &addr,
831	fn: i2c_check_mux_children);
832
833	return result;
834	}
835
836	/**
837	* i2c_adapter_lock_bus - Get exclusive access to an I2C bus segment
838	* @adapter: Target I2C bus segment
839	* @flags: I2C_LOCK_ROOT_ADAPTER locks the root i2c adapter, I2C_LOCK_SEGMENT
840	* locks only this branch in the adapter tree
841	*/
842	static void i2c_adapter_lock_bus(struct i2c_adapter *adapter,
843	unsigned int flags)
844	{
845	rt_mutex_lock_nested(lock: &adapter->bus_lock, subclass: i2c_adapter_depth(adapter));
846	}
847
848	/**
849	* i2c_adapter_trylock_bus - Try to get exclusive access to an I2C bus segment
850	* @adapter: Target I2C bus segment
851	* @flags: I2C_LOCK_ROOT_ADAPTER trylocks the root i2c adapter, I2C_LOCK_SEGMENT
852	* trylocks only this branch in the adapter tree
853	*/
854	static int i2c_adapter_trylock_bus(struct i2c_adapter *adapter,
855	unsigned int flags)
856	{
857	return rt_mutex_trylock(lock: &adapter->bus_lock);
858	}
859
860	/**
861	* i2c_adapter_unlock_bus - Release exclusive access to an I2C bus segment
862	* @adapter: Target I2C bus segment
863	* @flags: I2C_LOCK_ROOT_ADAPTER unlocks the root i2c adapter, I2C_LOCK_SEGMENT
864	* unlocks only this branch in the adapter tree
865	*/
866	static void i2c_adapter_unlock_bus(struct i2c_adapter *adapter,
867	unsigned int flags)
868	{
869	rt_mutex_unlock(lock: &adapter->bus_lock);
870	}
871
872	static void i2c_dev_set_name(struct i2c_adapter *adap,
873	struct i2c_client *client,
874	struct i2c_board_info const *info)
875	{
876	struct acpi_device *adev = ACPI_COMPANION(&client->dev);
877
878	if (info && info->dev_name) {
879	dev_set_name(dev: &client->dev, name: "i2c-%s", info->dev_name);
880	return;
881	}
882
883	if (adev) {
884	dev_set_name(dev: &client->dev, name: "i2c-%s", acpi_dev_name(adev));
885	return;
886	}
887
888	dev_set_name(dev: &client->dev, name: "%d-%04x", i2c_adapter_id(adap),
889	i2c_encode_flags_to_addr(client));
890	}
891
892	int i2c_dev_irq_from_resources(const struct resource *resources,
893	unsigned int num_resources)
894	{
895	struct irq_data *irqd;
896	int i;
897
898	for (i = `0`; i < num_resources; i++) {
899	const struct resource *r = &resources[i];
900
901	if (resource_type(res: r) != IORESOURCE_IRQ)
902	continue;
903
904	if (r->flags & IORESOURCE_BITS) {
905	irqd = irq_get_irq_data(irq: r->start);
906	if (!irqd)
907	break;
908
909	irqd_set_trigger_type(d: irqd, type: r->flags & IORESOURCE_BITS);
910	}
911
912	return r->start;
913	}
914
915	return `0`;
916	}
917
918	/**
919	* i2c_new_client_device - instantiate an i2c device
920	* @adap: the adapter managing the device
921	* @info: describes one I2C device; bus_num is ignored
922	* Context: can sleep
923	*
924	* Create an i2c device. Binding is handled through driver model
925	* probe()/remove() methods. A driver may be bound to this device when we
926	* return from this function, or any later moment (e.g. maybe hotplugging will
927	* load the driver module). This call is not appropriate for use by mainboard
928	* initialization logic, which usually runs during an arch_initcall() long
929	* before any i2c_adapter could exist.
930	*
931	* This returns the new i2c client, which may be saved for later use with
932	* i2c_unregister_device(); or an ERR_PTR to describe the error.
933	*/
934	struct i2c_client *
935	i2c_new_client_device(struct i2c_adapter adap, struct* i2c_board_info const *info)
936	{
937	struct i2c_client *client;
938	bool need_put = false;
939	int status;
940
941	client = kzalloc(size: sizeof *client, GFP_KERNEL);
942	if (!client)
943	return ERR_PTR(error: -ENOMEM);
944
945	client->adapter = adap;
946
947	client->dev.platform_data = info->platform_data;
948	client->flags = info->flags;
949	client->addr = info->addr;
950
951	client->init_irq = info->irq;
952	if (!client->init_irq)
953	client->init_irq = i2c_dev_irq_from_resources(resources: info->resources,
954	num_resources: info->num_resources);
955
956	strscpy(client->name, info->type, sizeof(client->name));
957
958	status = i2c_check_addr_validity(addr: client->addr, flags: client->flags);
959	if (status) {
960	dev_err(&adap->dev, "Invalid %d-bit I2C address 0x%02hx\n",
961	client->flags & I2C_CLIENT_TEN ? `10` : `7`, client->addr);
962	goto out_err_silent;
963	}
964
965	/ Check for address business /
966	status = i2c_check_addr_busy(adapter: adap, addr: i2c_encode_flags_to_addr(client));
967	if (status)
968	goto out_err;
969
970	client->dev.parent = &client->adapter->dev;
971	client->dev.bus = &i2c_bus_type;
972	client->dev.type = &i2c_client_type;
973	client->dev.of_node = of_node_get(node: info->of_node);
974	client->dev.fwnode = info->fwnode;
975
976	device_enable_async_suspend(dev: &client->dev);
977
978	if (info->swnode) {
979	status = device_add_software_node(dev: &client->dev, node: info->swnode);
980	if (status) {
981	dev_err(&adap->dev,
982	"Failed to add software node to client %s: %d\n",
983	client->name, status);
984	goto out_err_put_of_node;
985	}
986	}
987
988	i2c_dev_set_name(adap, client, info);
989	status = device_register(dev: &client->dev);
990	if (status)
991	goto out_remove_swnode;
992
993	dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n",
994	client->name, dev_name(&client->dev));
995
996	return client;
997
998	out_remove_swnode:
999	device_remove_software_node(dev: &client->dev);
1000	need_put = true;
1001	out_err_put_of_node:
1002	of_node_put(node: info->of_node);
1003	out_err:
1004	dev_err(&adap->dev,
1005	"Failed to register i2c client %s at 0x%02x (%d)\n",
1006	client->name, client->addr, status);
1007	out_err_silent:
1008	if (need_put)
1009	put_device(dev: &client->dev);
1010	else
1011	kfree(objp: client);
1012	return ERR_PTR(error: status);
1013	}
1014	EXPORT_SYMBOL_GPL(i2c_new_client_device);
1015
1016	/**
1017	* i2c_unregister_device - reverse effect of i2c_new_*_device()
1018	* @client: value returned from i2c_new_*_device()
1019	* Context: can sleep
1020	*/
1021	void i2c_unregister_device(struct i2c_client *client)
1022	{
1023	if (IS_ERR_OR_NULL(ptr: client))
1024	return;
1025
1026	if (client->dev.of_node) {
1027	of_node_clear_flag(n: client->dev.of_node, OF_POPULATED);
1028	of_node_put(node: client->dev.of_node);
1029	}
1030
1031	if (ACPI_COMPANION(&client->dev))
1032	acpi_device_clear_enumerated(ACPI_COMPANION(&client->dev));
1033	device_remove_software_node(dev: &client->dev);
1034	device_unregister(dev: &client->dev);
1035	}
1036	EXPORT_SYMBOL_GPL(i2c_unregister_device);
1037
1038	/**
1039	* i2c_find_device_by_fwnode() - find an i2c_client for the fwnode
1040	* @fwnode: &struct fwnode_handle corresponding to the &struct i2c_client
1041	*
1042	* Look up and return the &struct i2c_client corresponding to the @fwnode.
1043	* If no client can be found, or @fwnode is NULL, this returns NULL.
1044	*
1045	* The user must call put_device(&client->dev) once done with the i2c client.
1046	*/
1047	struct i2c_client i2c_find_device_by_fwnode(struct* fwnode_handle *fwnode)
1048	{
1049	struct i2c_client *client;
1050	struct device *dev;
1051
1052	if (!fwnode)
1053	return NULL;
1054
1055	dev = bus_find_device_by_fwnode(bus: &i2c_bus_type, fwnode);
1056	if (!dev)
1057	return NULL;
1058
1059	client = i2c_verify_client(dev);
1060	if (!client)
1061	put_device(dev);
1062
1063	return client;
1064	}
1065	EXPORT_SYMBOL(i2c_find_device_by_fwnode);
1066
1067
1068	static const struct i2c_device_id dummy_id[] = {
1069	{ "dummy", `0` },
1070	{ },
1071	};
1072
1073	static int dummy_probe(struct i2c_client *client)
1074	{
1075	return `0`;
1076	}
1077
1078	static struct i2c_driver dummy_driver = {
1079	.driver.name = "dummy",
1080	.probe = dummy_probe,
1081	.id_table = dummy_id,
1082	};
1083
1084	/**
1085	* i2c_new_dummy_device - return a new i2c device bound to a dummy driver
1086	* @adapter: the adapter managing the device
1087	* @address: seven bit address to be used
1088	* Context: can sleep
1089	*
1090	* This returns an I2C client bound to the "dummy" driver, intended for use
1091	* with devices that consume multiple addresses. Examples of such chips
1092	* include various EEPROMS (like 24c04 and 24c08 models).
1093	*
1094	* These dummy devices have two main uses. First, most I2C and SMBus calls
1095	* except i2c_transfer() need a client handle; the dummy will be that handle.
1096	* And second, this prevents the specified address from being bound to a
1097	* different driver.
1098	*
1099	* This returns the new i2c client, which should be saved for later use with
1100	* i2c_unregister_device(); or an ERR_PTR to describe the error.
1101	*/
1102	struct i2c_client i2c_new_dummy_device(struct* i2c_adapter *adapter, u16 address)
1103	{
1104	struct i2c_board_info info = {
1105	I2C_BOARD_INFO("dummy", address),
1106	};
1107
1108	return i2c_new_client_device(adapter, &info);
1109	}
1110	EXPORT_SYMBOL_GPL(i2c_new_dummy_device);
1111
1112	static void devm_i2c_release_dummy(void *client)
1113	{
1114	i2c_unregister_device(client);
1115	}
1116
1117	/**
1118	* devm_i2c_new_dummy_device - return a new i2c device bound to a dummy driver
1119	* @dev: device the managed resource is bound to
1120	* @adapter: the adapter managing the device
1121	* @address: seven bit address to be used
1122	* Context: can sleep
1123	*
1124	* This is the device-managed version of @i2c_new_dummy_device. It returns the
1125	* new i2c client or an ERR_PTR in case of an error.
1126	*/
1127	struct i2c_client devm_i2c_new_dummy_device(struct* device *dev,
1128	struct i2c_adapter *adapter,
1129	u16 address)
1130	{
1131	struct i2c_client *client;
1132	int ret;
1133
1134	client = i2c_new_dummy_device(adapter, address);
1135	if (IS_ERR(ptr: client))
1136	return client;
1137
1138	ret = devm_add_action_or_reset(dev, devm_i2c_release_dummy, client);
1139	if (ret)
1140	return ERR_PTR(error: ret);
1141
1142	return client;
1143	}
1144	EXPORT_SYMBOL_GPL(devm_i2c_new_dummy_device);
1145
1146	/**
1147	* i2c_new_ancillary_device - Helper to get the instantiated secondary address
1148	* and create the associated device
1149	* @client: Handle to the primary client
1150	* @name: Handle to specify which secondary address to get
1151	* @default_addr: Used as a fallback if no secondary address was specified
1152	* Context: can sleep
1153	*
1154	* I2C clients can be composed of multiple I2C slaves bound together in a single
1155	* component. The I2C client driver then binds to the master I2C slave and needs
1156	* to create I2C dummy clients to communicate with all the other slaves.
1157	*
1158	* This function creates and returns an I2C dummy client whose I2C address is
1159	* retrieved from the platform firmware based on the given slave name. If no
1160	* address is specified by the firmware default_addr is used.
1161	*
1162	* On DT-based platforms the address is retrieved from the "reg" property entry
1163	* cell whose "reg-names" value matches the slave name.
1164	*
1165	* This returns the new i2c client, which should be saved for later use with
1166	* i2c_unregister_device(); or an ERR_PTR to describe the error.
1167	*/
1168	struct i2c_client i2c_new_ancillary_device(struct* i2c_client *client,
1169	const char *name,
1170	u16 default_addr)
1171	{
1172	struct device_node *np = client->dev.of_node;
1173	u32 addr = default_addr;
1174	int i;
1175
1176	if (np) {
1177	i = of_property_match_string(np, propname: "reg-names", string: name);
1178	if (i >= `0`)
1179	of_property_read_u32_index(np, propname: "reg", index: i, out_value: &addr);
1180	}
1181
1182	dev_dbg(&client->adapter->dev, "Address for %s : 0x%x\n", name, addr);
1183	return i2c_new_dummy_device(client->adapter, addr);
1184	}
1185	EXPORT_SYMBOL_GPL(i2c_new_ancillary_device);
1186
1187	/ ------------------------------------------------------------------------- /
1188
1189	/ I2C bus adapters -- one roots each I2C or SMBUS segment /
1190
1191	static void i2c_adapter_dev_release(struct device *dev)
1192	{
1193	struct i2c_adapter *adap = to_i2c_adapter(dev);
1194	complete(&adap->dev_released);
1195	}
1196
1197	unsigned int i2c_adapter_depth(struct i2c_adapter *adapter)
1198	{
1199	unsigned int depth = `0`;
1200	struct device *parent;
1201
1202	for (parent = adapter->dev.parent; parent; parent = parent->parent)
1203	if (parent->type == &i2c_adapter_type)
1204	depth++;
1205
1206	WARN_ONCE(depth >= MAX_LOCKDEP_SUBCLASSES,
1207	"adapter depth exceeds lockdep subclass limit\n");
1208
1209	return depth;
1210	}
1211	EXPORT_SYMBOL_GPL(i2c_adapter_depth);
1212
1213	/*
1214	* Let users instantiate I2C devices through sysfs. This can be used when
1215	* platform initialization code doesn't contain the proper data for
1216	* whatever reason. Also useful for drivers that do device detection and
1217	* detection fails, either because the device uses an unexpected address,
1218	* or this is a compatible device with different ID register values.
1219	*
1220	* Parameter checking may look overzealous, but we really don't want
1221	* the user to provide incorrect parameters.
1222	*/
1223	static ssize_t
1224	new_device_store(struct device dev, struct* device_attribute *attr,
1225	const char *buf, size_t count)
1226	{
1227	struct i2c_adapter *adap = to_i2c_adapter(dev);
1228	struct i2c_board_info info;
1229	struct i2c_client *client;
1230	char *blank, end;
1231	int res;
1232
1233	memset(&info, `0`, sizeof(struct i2c_board_info));
1234
1235	blank = strchr(buf, `' '`);
1236	if (!blank) {
1237	dev_err(dev, "%s: Missing parameters\n", "new_device");
1238	return -EINVAL;
1239	}
1240	if (blank - buf > I2C_NAME_SIZE - `1`) {
1241	dev_err(dev, "%s: Invalid device name\n", "new_device");
1242	return -EINVAL;
1243	}
1244	memcpy(info.type, buf, blank - buf);
1245
1246	/ Parse remaining parameters, reject extra parameters /
1247	res = sscanf(++blank, "%hi%c", &info.addr, &end);
1248	if (res < `1`) {
1249	dev_err(dev, "%s: Can't parse I2C address\n", "new_device");
1250	return -EINVAL;
1251	}
1252	if (res > `1` && end != `'\n'`) {
1253	dev_err(dev, "%s: Extra parameters\n", "new_device");
1254	return -EINVAL;
1255	}
1256
1257	if ((info.addr & I2C_ADDR_OFFSET_TEN_BIT) == I2C_ADDR_OFFSET_TEN_BIT) {
1258	info.addr &= ~I2C_ADDR_OFFSET_TEN_BIT;
1259	info.flags \|= I2C_CLIENT_TEN;
1260	}
1261
1262	if (info.addr & I2C_ADDR_OFFSET_SLAVE) {
1263	info.addr &= ~I2C_ADDR_OFFSET_SLAVE;
1264	info.flags \|= I2C_CLIENT_SLAVE;
1265	}
1266
1267	client = i2c_new_client_device(adap, &info);
1268	if (IS_ERR(ptr: client))
1269	return PTR_ERR(ptr: client);
1270
1271	/ Keep track of the added device /
1272	mutex_lock(&adap->userspace_clients_lock);
1273	list_add_tail(new: &client->detected, head: &adap->userspace_clients);
1274	mutex_unlock(lock: &adap->userspace_clients_lock);
1275	dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",
1276	info.type, info.addr);
1277
1278	return count;
1279	}
1280	static DEVICE_ATTR_WO(new_device);
1281
1282	/*
1283	* And of course let the users delete the devices they instantiated, if
1284	* they got it wrong. This interface can only be used to delete devices
1285	* instantiated by i2c_sysfs_new_device above. This guarantees that we
1286	* don't delete devices to which some kernel code still has references.
1287	*
1288	* Parameter checking may look overzealous, but we really don't want
1289	* the user to delete the wrong device.
1290	*/
1291	static ssize_t
1292	delete_device_store(struct device dev, struct* device_attribute *attr,
1293	const char *buf, size_t count)
1294	{
1295	struct i2c_adapter *adap = to_i2c_adapter(dev);
1296	struct i2c_client client, next;
1297	unsigned short addr;
1298	char end;
1299	int res;
1300
1301	/ Parse parameters, reject extra parameters /
1302	res = sscanf(buf, "%hi%c", &addr, &end);
1303	if (res < `1`) {
1304	dev_err(dev, "%s: Can't parse I2C address\n", "delete_device");
1305	return -EINVAL;
1306	}
1307	if (res > `1` && end != `'\n'`) {
1308	dev_err(dev, "%s: Extra parameters\n", "delete_device");
1309	return -EINVAL;
1310	}
1311
1312	/ Make sure the device was added through sysfs /
1313	res = -ENOENT;
1314	mutex_lock_nested(lock: &adap->userspace_clients_lock,
1315	subclass: i2c_adapter_depth(adap));
1316	list_for_each_entry_safe(client, next, &adap->userspace_clients,
1317	detected) {
1318	if (i2c_encode_flags_to_addr(client) == addr) {
1319	dev_info(dev, "%s: Deleting device %s at 0x%02hx\n",
1320	"delete_device", client->name, client->addr);
1321
1322	list_del(entry: &client->detected);
1323	i2c_unregister_device(client);
1324	res = count;
1325	break;
1326	}
1327	}
1328	mutex_unlock(lock: &adap->userspace_clients_lock);
1329
1330	if (res < `0`)
1331	dev_err(dev, "%s: Can't find device in list\n",
1332	"delete_device");
1333	return res;
1334	}
1335	static DEVICE_ATTR_IGNORE_LOCKDEP(delete_device, S_IWUSR, NULL,
1336	delete_device_store);
1337
1338	static struct attribute *i2c_adapter_attrs[] = {
1339	&dev_attr_name.attr,
1340	&dev_attr_new_device.attr,
1341	&dev_attr_delete_device.attr,
1342	NULL
1343	};
1344	ATTRIBUTE_GROUPS(i2c_adapter);
1345
1346	const struct device_type i2c_adapter_type = {
1347	.groups = i2c_adapter_groups,
1348	.release = i2c_adapter_dev_release,
1349	};
1350	EXPORT_SYMBOL_GPL(i2c_adapter_type);
1351
1352	/**
1353	* i2c_verify_adapter - return parameter as i2c_adapter or NULL
1354	* @dev: device, probably from some driver model iterator
1355	*
1356	* When traversing the driver model tree, perhaps using driver model
1357	* iterators like @device_for_each_child(), you can't assume very much
1358	* about the nodes you find. Use this function to avoid oopses caused
1359	* by wrongly treating some non-I2C device as an i2c_adapter.
1360	*/
1361	struct i2c_adapter i2c_verify_adapter(struct* device *dev)
1362	{
1363	return (dev->type == &i2c_adapter_type)
1364	? to_i2c_adapter(dev)
1365	: NULL;
1366	}
1367	EXPORT_SYMBOL(i2c_verify_adapter);
1368
1369	#ifdef CONFIG_I2C_COMPAT
1370	static struct class_compat *i2c_adapter_compat_class;
1371	#endif
1372
1373	static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
1374	{
1375	struct i2c_devinfo *devinfo;
1376
1377	down_read(sem: &__i2c_board_lock);
1378	list_for_each_entry(devinfo, &__i2c_board_list, list) {
1379	if (devinfo->busnum == adapter->nr &&
1380	IS_ERR(ptr: i2c_new_client_device(adapter, &devinfo->board_info)))
1381	dev_err(&adapter->dev,
1382	"Can't create device at 0x%02x\n",
1383	devinfo->board_info.addr);
1384	}
1385	up_read(sem: &__i2c_board_lock);
1386	}
1387
1388	static int i2c_do_add_adapter(struct i2c_driver *driver,
1389	struct i2c_adapter *adap)
1390	{
1391	/ Detect supported devices on that bus, and instantiate them /
1392	i2c_detect(adapter: adap, driver);
1393
1394	return `0`;
1395	}
1396
1397	static int __process_new_adapter(struct device_driver d, void* *data)
1398	{
1399	return i2c_do_add_adapter(to_i2c_driver(d), adap: data);
1400	}
1401
1402	static const struct i2c_lock_operations i2c_adapter_lock_ops = {
1403	.lock_bus = i2c_adapter_lock_bus,
1404	.trylock_bus = i2c_adapter_trylock_bus,
1405	.unlock_bus = i2c_adapter_unlock_bus,
1406	};
1407
1408	static void i2c_host_notify_irq_teardown(struct i2c_adapter *adap)
1409	{
1410	struct irq_domain *domain = adap->host_notify_domain;
1411	irq_hw_number_t hwirq;
1412
1413	if (!domain)
1414	return;
1415
1416	for (hwirq = `0` ; hwirq < I2C_ADDR_7BITS_COUNT ; hwirq++)
1417	irq_dispose_mapping(virq: irq_find_mapping(domain, hwirq));
1418
1419	irq_domain_remove(host: domain);
1420	adap->host_notify_domain = NULL;
1421	}
1422
1423	static int i2c_host_notify_irq_map(struct irq_domain *h,
1424	unsigned int virq,
1425	irq_hw_number_t hw_irq_num)
1426	{
1427	irq_set_chip_and_handler(irq: virq, chip: &dummy_irq_chip, handle: handle_simple_irq);
1428
1429	return `0`;
1430	}
1431
1432	static const struct irq_domain_ops i2c_host_notify_irq_ops = {
1433	.map = i2c_host_notify_irq_map,
1434	};
1435
1436	static int i2c_setup_host_notify_irq_domain(struct i2c_adapter *adap)
1437	{
1438	struct irq_domain *domain;
1439
1440	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_HOST_NOTIFY))
1441	return `0`;
1442
1443	domain = irq_domain_create_linear(fwnode: adap->dev.parent->fwnode,
1444	I2C_ADDR_7BITS_COUNT,
1445	ops: &i2c_host_notify_irq_ops, host_data: adap);
1446	if (!domain)
1447	return -ENOMEM;
1448
1449	adap->host_notify_domain = domain;
1450
1451	return `0`;
1452	}
1453
1454	/**
1455	* i2c_handle_smbus_host_notify - Forward a Host Notify event to the correct
1456	* I2C client.
1457	* @adap: the adapter
1458	* @addr: the I2C address of the notifying device
1459	* Context: can't sleep
1460	*
1461	* Helper function to be called from an I2C bus driver's interrupt
1462	* handler. It will schedule the Host Notify IRQ.
1463	*/
1464	int i2c_handle_smbus_host_notify(struct i2c_adapter adap, unsigned* short addr)
1465	{
1466	int irq;
1467
1468	if (!adap)
1469	return -EINVAL;
1470
1471	irq = irq_find_mapping(domain: adap->host_notify_domain, hwirq: addr);
1472	if (irq <= `0`)
1473	return -ENXIO;
1474
1475	generic_handle_irq_safe(irq);
1476
1477	return `0`;
1478	}
1479	EXPORT_SYMBOL_GPL(i2c_handle_smbus_host_notify);
1480
1481	static int i2c_register_adapter(struct i2c_adapter *adap)
1482	{
1483	int res = -EINVAL;
1484
1485	/ Can't register until after driver model init /
1486	if (WARN_ON(!is_registered)) {
1487	res = -EAGAIN;
1488	goto out_list;
1489	}
1490
1491	/ Sanity checks /
1492	if (WARN(!adap->name[`0`], "i2c adapter has no name"))
1493	goto out_list;
1494
1495	if (!adap->algo) {
1496	pr_err("adapter '%s': no algo supplied!\n", adap->name);
1497	goto out_list;
1498	}
1499
1500	if (!adap->lock_ops)
1501	adap->lock_ops = &i2c_adapter_lock_ops;
1502
1503	adap->locked_flags = `0`;
1504	rt_mutex_init(&adap->bus_lock);
1505	rt_mutex_init(&adap->mux_lock);
1506	mutex_init(&adap->userspace_clients_lock);
1507	INIT_LIST_HEAD(list: &adap->userspace_clients);
1508
1509	/ Set default timeout to 1 second if not already set /
1510	if (adap->timeout == `0`)
1511	adap->timeout = HZ;
1512
1513	/ register soft irqs for Host Notify /
1514	res = i2c_setup_host_notify_irq_domain(adap);
1515	if (res) {
1516	pr_err("adapter '%s': can't create Host Notify IRQs (%d)\n",
1517	adap->name, res);
1518	goto out_list;
1519	}
1520
1521	dev_set_name(dev: &adap->dev, name: "i2c-%d", adap->nr);
1522	adap->dev.bus = &i2c_bus_type;
1523	adap->dev.type = &i2c_adapter_type;
1524	res = device_register(dev: &adap->dev);
1525	if (res) {
1526	pr_err("adapter '%s': can't register device (%d)\n", adap->name, res);
1527	goto out_list;
1528	}
1529
1530	adap->debugfs = debugfs_create_dir(name: dev_name(dev: &adap->dev), parent: i2c_debugfs_root);
1531
1532	res = i2c_setup_smbus_alert(adap);
1533	if (res)
1534	goto out_reg;
1535
1536	device_enable_async_suspend(dev: &adap->dev);
1537	pm_runtime_no_callbacks(dev: &adap->dev);
1538	pm_suspend_ignore_children(dev: &adap->dev, enable: true);
1539	pm_runtime_enable(dev: &adap->dev);
1540
1541	res = i2c_init_recovery(adap);
1542	if (res == -EPROBE_DEFER)
1543	goto out_reg;
1544
1545	dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
1546
1547	#ifdef CONFIG_I2C_COMPAT
1548	res = class_compat_create_link(cls: i2c_adapter_compat_class, dev: &adap->dev,
1549	device_link: adap->dev.parent);
1550	if (res)
1551	dev_warn(&adap->dev,
1552	"Failed to create compatibility class link\n");
1553	#endif
1554
1555	/ create pre-declared device nodes /
1556	of_i2c_register_devices(adap);
1557	i2c_acpi_install_space_handler(adapter: adap);
1558	i2c_acpi_register_devices(adap);
1559
1560	if (adap->nr < __i2c_first_dynamic_bus_num)
1561	i2c_scan_static_board_info(adapter: adap);
1562
1563	/ Notify drivers /
1564	mutex_lock(&core_lock);
1565	bus_for_each_drv(bus: &i2c_bus_type, NULL, data: adap, fn: __process_new_adapter);
1566	mutex_unlock(lock: &core_lock);
1567
1568	return `0`;
1569
1570	out_reg:
1571	debugfs_remove_recursive(dentry: adap->debugfs);
1572	init_completion(x: &adap->dev_released);
1573	device_unregister(dev: &adap->dev);
1574	wait_for_completion(&adap->dev_released);
1575	out_list:
1576	mutex_lock(&core_lock);
1577	idr_remove(&i2c_adapter_idr, id: adap->nr);
1578	mutex_unlock(lock: &core_lock);
1579	return res;
1580	}
1581
1582	/**
1583	* __i2c_add_numbered_adapter - i2c_add_numbered_adapter where nr is never -1
1584	* @adap: the adapter to register (with adap->nr initialized)
1585	* Context: can sleep
1586	*
1587	* See i2c_add_numbered_adapter() for details.
1588	*/
1589	static int __i2c_add_numbered_adapter(struct i2c_adapter *adap)
1590	{
1591	int id;
1592
1593	mutex_lock(&core_lock);
1594	id = idr_alloc(&i2c_adapter_idr, ptr: adap, start: adap->nr, end: adap->nr + `1`, GFP_KERNEL);
1595	mutex_unlock(lock: &core_lock);
1596	if (WARN(id < `0`, "couldn't get idr"))
1597	return id == -ENOSPC ? -EBUSY : id;
1598
1599	return i2c_register_adapter(adap);
1600	}
1601
1602	/**
1603	* i2c_add_adapter - declare i2c adapter, use dynamic bus number
1604	* @adapter: the adapter to add
1605	* Context: can sleep
1606	*
1607	* This routine is used to declare an I2C adapter when its bus number
1608	* doesn't matter or when its bus number is specified by an dt alias.
1609	* Examples of bases when the bus number doesn't matter: I2C adapters
1610	* dynamically added by USB links or PCI plugin cards.
1611	*
1612	* When this returns zero, a new bus number was allocated and stored
1613	* in adap->nr, and the specified adapter became available for clients.
1614	* Otherwise, a negative errno value is returned.
1615	*/
1616	int i2c_add_adapter(struct i2c_adapter *adapter)
1617	{
1618	struct device *dev = &adapter->dev;
1619	int id;
1620
1621	if (dev->of_node) {
1622	id = of_alias_get_id(np: dev->of_node, stem: "i2c");
1623	if (id >= `0`) {
1624	adapter->nr = id;
1625	return __i2c_add_numbered_adapter(adap: adapter);
1626	}
1627	}
1628
1629	mutex_lock(&core_lock);
1630	id = idr_alloc(&i2c_adapter_idr, ptr: adapter,
1631	start: __i2c_first_dynamic_bus_num, end: `0`, GFP_KERNEL);
1632	mutex_unlock(lock: &core_lock);
1633	if (WARN(id < `0`, "couldn't get idr"))
1634	return id;
1635
1636	adapter->nr = id;
1637
1638	return i2c_register_adapter(adap: adapter);
1639	}
1640	EXPORT_SYMBOL(i2c_add_adapter);
1641
1642	/**
1643	* i2c_add_numbered_adapter - declare i2c adapter, use static bus number
1644	* @adap: the adapter to register (with adap->nr initialized)
1645	* Context: can sleep
1646	*
1647	* This routine is used to declare an I2C adapter when its bus number
1648	* matters. For example, use it for I2C adapters from system-on-chip CPUs,
1649	* or otherwise built in to the system's mainboard, and where i2c_board_info
1650	* is used to properly configure I2C devices.
1651	*
1652	* If the requested bus number is set to -1, then this function will behave
1653	* identically to i2c_add_adapter, and will dynamically assign a bus number.
1654	*
1655	* If no devices have pre-been declared for this bus, then be sure to
1656	* register the adapter before any dynamically allocated ones. Otherwise
1657	* the required bus ID may not be available.
1658	*
1659	* When this returns zero, the specified adapter became available for
1660	* clients using the bus number provided in adap->nr. Also, the table
1661	* of I2C devices pre-declared using i2c_register_board_info() is scanned,
1662	* and the appropriate driver model device nodes are created. Otherwise, a
1663	* negative errno value is returned.
1664	*/
1665	int i2c_add_numbered_adapter(struct i2c_adapter *adap)
1666	{
1667	if (adap->nr == -`1`) / -1 means dynamically assign bus id /
1668	return i2c_add_adapter(adap);
1669
1670	return __i2c_add_numbered_adapter(adap);
1671	}
1672	EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);
1673
1674	static void i2c_do_del_adapter(struct i2c_driver *driver,
1675	struct i2c_adapter *adapter)
1676	{
1677	struct i2c_client client, _n;
1678
1679	/ Remove the devices we created ourselves as the result of hardware*
1680	* probing (using a driver's detect method) */
1681	list_for_each_entry_safe(client, _n, &driver->clients, detected) {
1682	if (client->adapter == adapter) {
1683	dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
1684	client->name, client->addr);
1685	list_del(entry: &client->detected);
1686	i2c_unregister_device(client);
1687	}
1688	}
1689	}
1690
1691	static int __unregister_client(struct device dev, void* *dummy)
1692	{
1693	struct i2c_client *client = i2c_verify_client(dev);
1694	if (client && strcmp(client->name, "dummy"))
1695	i2c_unregister_device(client);
1696	return `0`;
1697	}
1698
1699	static int __unregister_dummy(struct device dev, void* *dummy)
1700	{
1701	struct i2c_client *client = i2c_verify_client(dev);
1702	i2c_unregister_device(client);
1703	return `0`;
1704	}
1705
1706	static int __process_removed_adapter(struct device_driver d, void* *data)
1707	{
1708	i2c_do_del_adapter(to_i2c_driver(d), adapter: data);
1709	return `0`;
1710	}
1711
1712	/**
1713	* i2c_del_adapter - unregister I2C adapter
1714	* @adap: the adapter being unregistered
1715	* Context: can sleep
1716	*
1717	* This unregisters an I2C adapter which was previously registered
1718	* by @i2c_add_adapter or @i2c_add_numbered_adapter.
1719	*/
1720	void i2c_del_adapter(struct i2c_adapter *adap)
1721	{
1722	struct i2c_adapter *found;
1723	struct i2c_client client, next;
1724
1725	/ First make sure that this adapter was ever added /
1726	mutex_lock(&core_lock);
1727	found = idr_find(&i2c_adapter_idr, id: adap->nr);
1728	mutex_unlock(lock: &core_lock);
1729	if (found != adap) {
1730	pr_debug("attempting to delete unregistered adapter [%s]\n", adap->name);
1731	return;
1732	}
1733
1734	i2c_acpi_remove_space_handler(adapter: adap);
1735	/ Tell drivers about this removal /
1736	mutex_lock(&core_lock);
1737	bus_for_each_drv(bus: &i2c_bus_type, NULL, data: adap,
1738	fn: __process_removed_adapter);
1739	mutex_unlock(lock: &core_lock);
1740
1741	/ Remove devices instantiated from sysfs /
1742	mutex_lock_nested(lock: &adap->userspace_clients_lock,
1743	subclass: i2c_adapter_depth(adap));
1744	list_for_each_entry_safe(client, next, &adap->userspace_clients,
1745	detected) {
1746	dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
1747	client->addr);
1748	list_del(entry: &client->detected);
1749	i2c_unregister_device(client);
1750	}
1751	mutex_unlock(lock: &adap->userspace_clients_lock);
1752
1753	/ Detach any active clients. This can't fail, thus we do not*
1754	* check the returned value. This is a two-pass process, because
1755	* we can't remove the dummy devices during the first pass: they
1756	* could have been instantiated by real devices wishing to clean
1757	* them up properly, so we give them a chance to do that first. */
1758	device_for_each_child(dev: &adap->dev, NULL, fn: __unregister_client);
1759	device_for_each_child(dev: &adap->dev, NULL, fn: __unregister_dummy);
1760
1761	#ifdef CONFIG_I2C_COMPAT
1762	class_compat_remove_link(cls: i2c_adapter_compat_class, dev: &adap->dev,
1763	device_link: adap->dev.parent);
1764	#endif
1765
1766	/ device name is gone after device_unregister /
1767	dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);
1768
1769	pm_runtime_disable(dev: &adap->dev);
1770
1771	i2c_host_notify_irq_teardown(adap);
1772
1773	debugfs_remove_recursive(dentry: adap->debugfs);
1774
1775	/ wait until all references to the device are gone*
1776	*
1777	* FIXME: This is old code and should ideally be replaced by an
1778	* alternative which results in decoupling the lifetime of the struct
1779	* device from the i2c_adapter, like spi or netdev do. Any solution
1780	* should be thoroughly tested with DEBUG_KOBJECT_RELEASE enabled!
1781	*/
1782	init_completion(x: &adap->dev_released);
1783	device_unregister(dev: &adap->dev);
1784	wait_for_completion(&adap->dev_released);
1785
1786	/ free bus id /
1787	mutex_lock(&core_lock);
1788	idr_remove(&i2c_adapter_idr, id: adap->nr);
1789	mutex_unlock(lock: &core_lock);
1790
1791	/ Clear the device structure in case this adapter is ever going to be*
1792	added again /*
1793	memset(&adap->dev, `0`, sizeof(adap->dev));
1794	}
1795	EXPORT_SYMBOL(i2c_del_adapter);
1796
1797	static void devm_i2c_del_adapter(void *adapter)
1798	{
1799	i2c_del_adapter(adapter);
1800	}
1801
1802	/**
1803	* devm_i2c_add_adapter - device-managed variant of i2c_add_adapter()
1804	* @dev: managing device for adding this I2C adapter
1805	* @adapter: the adapter to add
1806	* Context: can sleep
1807	*
1808	* Add adapter with dynamic bus number, same with i2c_add_adapter()
1809	* but the adapter will be auto deleted on driver detach.
1810	*/
1811	int devm_i2c_add_adapter(struct device dev, struct* i2c_adapter *adapter)
1812	{
1813	int ret;
1814
1815	ret = i2c_add_adapter(adapter);
1816	if (ret)
1817	return ret;
1818
1819	return devm_add_action_or_reset(dev, devm_i2c_del_adapter, adapter);
1820	}
1821	EXPORT_SYMBOL_GPL(devm_i2c_add_adapter);
1822
1823	static int i2c_dev_or_parent_fwnode_match(struct device dev, const* void *data)
1824	{
1825	if (dev_fwnode(dev) == data)
1826	return `1`;
1827
1828	if (dev->parent && dev_fwnode(dev->parent) == data)
1829	return `1`;
1830
1831	return `0`;
1832	}
1833
1834	/**
1835	* i2c_find_adapter_by_fwnode() - find an i2c_adapter for the fwnode
1836	* @fwnode: &struct fwnode_handle corresponding to the &struct i2c_adapter
1837	*
1838	* Look up and return the &struct i2c_adapter corresponding to the @fwnode.
1839	* If no adapter can be found, or @fwnode is NULL, this returns NULL.
1840	*
1841	* The user must call put_device(&adapter->dev) once done with the i2c adapter.
1842	*/
1843	struct i2c_adapter i2c_find_adapter_by_fwnode(struct* fwnode_handle *fwnode)
1844	{
1845	struct i2c_adapter *adapter;
1846	struct device *dev;
1847
1848	if (!fwnode)
1849	return NULL;
1850
1851	dev = bus_find_device(bus: &i2c_bus_type, NULL, data: fwnode,
1852	match: i2c_dev_or_parent_fwnode_match);
1853	if (!dev)
1854	return NULL;
1855
1856	adapter = i2c_verify_adapter(dev);
1857	if (!adapter)
1858	put_device(dev);
1859
1860	return adapter;
1861	}
1862	EXPORT_SYMBOL(i2c_find_adapter_by_fwnode);
1863
1864	/**
1865	* i2c_get_adapter_by_fwnode() - find an i2c_adapter for the fwnode
1866	* @fwnode: &struct fwnode_handle corresponding to the &struct i2c_adapter
1867	*
1868	* Look up and return the &struct i2c_adapter corresponding to the @fwnode,
1869	* and increment the adapter module's use count. If no adapter can be found,
1870	* or @fwnode is NULL, this returns NULL.
1871	*
1872	* The user must call i2c_put_adapter(adapter) once done with the i2c adapter.
1873	* Note that this is different from i2c_find_adapter_by_node().
1874	*/
1875	struct i2c_adapter i2c_get_adapter_by_fwnode(struct* fwnode_handle *fwnode)
1876	{
1877	struct i2c_adapter *adapter;
1878
1879	adapter = i2c_find_adapter_by_fwnode(fwnode);
1880	if (!adapter)
1881	return NULL;
1882
1883	if (!try_module_get(module: adapter->owner)) {
1884	put_device(dev: &adapter->dev);
1885	adapter = NULL;
1886	}
1887
1888	return adapter;
1889	}
1890	EXPORT_SYMBOL(i2c_get_adapter_by_fwnode);
1891
1892	static void i2c_parse_timing(struct device dev, char* prop_name, u32 cur_val_p,
1893	u32 def_val, bool use_def)
1894	{
1895	int ret;
1896
1897	ret = device_property_read_u32(dev, propname: prop_name, val: cur_val_p);
1898	if (ret && use_def)
1899	*cur_val_p = def_val;
1900
1901	dev_dbg(dev, "%s: %u\n", prop_name, *cur_val_p);
1902	}
1903
1904	/**
1905	* i2c_parse_fw_timings - get I2C related timing parameters from firmware
1906	* @dev: The device to scan for I2C timing properties
1907	* @t: the i2c_timings struct to be filled with values
1908	* @use_defaults: bool to use sane defaults derived from the I2C specification
1909	* when properties are not found, otherwise don't update
1910	*
1911	* Scan the device for the generic I2C properties describing timing parameters
1912	* for the signal and fill the given struct with the results. If a property was
1913	* not found and use_defaults was true, then maximum timings are assumed which
1914	* are derived from the I2C specification. If use_defaults is not used, the
1915	* results will be as before, so drivers can apply their own defaults before
1916	* calling this helper. The latter is mainly intended for avoiding regressions
1917	* of existing drivers which want to switch to this function. New drivers
1918	* almost always should use the defaults.
1919	*/
1920	void i2c_parse_fw_timings(struct device dev, struct* i2c_timings *t, bool use_defaults)
1921	{
1922	bool u = use_defaults;
1923	u32 d;
1924
1925	i2c_parse_timing(dev, prop_name: "clock-frequency", cur_val_p: &t->bus_freq_hz,
1926	I2C_MAX_STANDARD_MODE_FREQ, use_def: u);
1927
1928	d = t->bus_freq_hz <= I2C_MAX_STANDARD_MODE_FREQ ? `1000` :
1929	t->bus_freq_hz <= I2C_MAX_FAST_MODE_FREQ ? `300` : `120`;
1930	i2c_parse_timing(dev, prop_name: "i2c-scl-rising-time-ns", cur_val_p: &t->scl_rise_ns, def_val: d, use_def: u);
1931
1932	d = t->bus_freq_hz <= I2C_MAX_FAST_MODE_FREQ ? `300` : `120`;
1933	i2c_parse_timing(dev, prop_name: "i2c-scl-falling-time-ns", cur_val_p: &t->scl_fall_ns, def_val: d, use_def: u);
1934
1935	i2c_parse_timing(dev, prop_name: "i2c-scl-internal-delay-ns",
1936	cur_val_p: &t->scl_int_delay_ns, def_val: `0`, use_def: u);
1937	i2c_parse_timing(dev, prop_name: "i2c-sda-falling-time-ns", cur_val_p: &t->sda_fall_ns,
1938	def_val: t->scl_fall_ns, use_def: u);
1939	i2c_parse_timing(dev, prop_name: "i2c-sda-hold-time-ns", cur_val_p: &t->sda_hold_ns, def_val: `0`, use_def: u);
1940	i2c_parse_timing(dev, prop_name: "i2c-digital-filter-width-ns",
1941	cur_val_p: &t->digital_filter_width_ns, def_val: `0`, use_def: u);
1942	i2c_parse_timing(dev, prop_name: "i2c-analog-filter-cutoff-frequency",
1943	cur_val_p: &t->analog_filter_cutoff_freq_hz, def_val: `0`, use_def: u);
1944	}
1945	EXPORT_SYMBOL_GPL(i2c_parse_fw_timings);
1946
1947	/ ------------------------------------------------------------------------- /
1948
1949	int i2c_for_each_dev(void data, int* (fn)(struct* device dev, void* *data))
1950	{
1951	int res;
1952
1953	mutex_lock(&core_lock);
1954	res = bus_for_each_dev(bus: &i2c_bus_type, NULL, data, fn);
1955	mutex_unlock(lock: &core_lock);
1956
1957	return res;
1958	}
1959	EXPORT_SYMBOL_GPL(i2c_for_each_dev);
1960
1961	static int __process_new_driver(struct device dev, void* *data)
1962	{
1963	if (dev->type != &i2c_adapter_type)
1964	return `0`;
1965	return i2c_do_add_adapter(driver: data, to_i2c_adapter(dev));
1966	}
1967
1968	/*
1969	* An i2c_driver is used with one or more i2c_client (device) nodes to access
1970	* i2c slave chips, on a bus instance associated with some i2c_adapter.
1971	*/
1972
1973	int i2c_register_driver(struct module owner, struct* i2c_driver *driver)
1974	{
1975	int res;
1976
1977	/ Can't register until after driver model init /
1978	if (WARN_ON(!is_registered))
1979	return -EAGAIN;
1980
1981	/ add the driver to the list of i2c drivers in the driver core /
1982	driver->driver.owner = owner;
1983	driver->driver.bus = &i2c_bus_type;
1984	INIT_LIST_HEAD(list: &driver->clients);
1985
1986	/ When registration returns, the driver core*
1987	* will have called probe() for all matching-but-unbound devices.
1988	*/
1989	res = driver_register(drv: &driver->driver);
1990	if (res)
1991	return res;
1992
1993	pr_debug("driver [%s] registered\n", driver->driver.name);
1994
1995	/ Walk the adapters that are already present /
1996	i2c_for_each_dev(driver, __process_new_driver);
1997
1998	return `0`;
1999	}
2000	EXPORT_SYMBOL(i2c_register_driver);
2001
2002	static int __process_removed_driver(struct device dev, void* *data)
2003	{
2004	if (dev->type == &i2c_adapter_type)
2005	i2c_do_del_adapter(driver: data, to_i2c_adapter(dev));
2006	return `0`;
2007	}
2008
2009	/**
2010	* i2c_del_driver - unregister I2C driver
2011	* @driver: the driver being unregistered
2012	* Context: can sleep
2013	*/
2014	void i2c_del_driver(struct i2c_driver *driver)
2015	{
2016	i2c_for_each_dev(driver, __process_removed_driver);
2017
2018	driver_unregister(drv: &driver->driver);
2019	pr_debug("driver [%s] unregistered\n", driver->driver.name);
2020	}
2021	EXPORT_SYMBOL(i2c_del_driver);
2022
2023	/ ------------------------------------------------------------------------- /
2024
2025	struct i2c_cmd_arg {
2026	unsigned cmd;
2027	void *arg;
2028	};
2029
2030	static int i2c_cmd(struct device dev, void* *_arg)
2031	{
2032	struct i2c_client *client = i2c_verify_client(dev);
2033	struct i2c_cmd_arg *arg = _arg;
2034	struct i2c_driver *driver;
2035
2036	if (!client \|\| !client->dev.driver)
2037	return `0`;
2038
2039	driver = to_i2c_driver(client->dev.driver);
2040	if (driver->command)
2041	driver->command(client, arg->cmd, arg->arg);
2042	return `0`;
2043	}
2044
2045	void i2c_clients_command(struct i2c_adapter adap, unsigned* int cmd, void *arg)
2046	{
2047	struct i2c_cmd_arg cmd_arg;
2048
2049	cmd_arg.cmd = cmd;
2050	cmd_arg.arg = arg;
2051	device_for_each_child(dev: &adap->dev, data: &cmd_arg, fn: i2c_cmd);
2052	}
2053	EXPORT_SYMBOL(i2c_clients_command);
2054
2055	static int __init i2c_init(void)
2056	{
2057	int retval;
2058
2059	retval = of_alias_get_highest_id(stem: "i2c");
2060
2061	down_write(sem: &__i2c_board_lock);
2062	if (retval >= __i2c_first_dynamic_bus_num)
2063	__i2c_first_dynamic_bus_num = retval + `1`;
2064	up_write(sem: &__i2c_board_lock);
2065
2066	retval = bus_register(bus: &i2c_bus_type);
2067	if (retval)
2068	return retval;
2069
2070	is_registered = true;
2071
2072	i2c_debugfs_root = debugfs_create_dir(name: "i2c", NULL);
2073
2074	#ifdef CONFIG_I2C_COMPAT
2075	i2c_adapter_compat_class = class_compat_register(name: "i2c-adapter");
2076	if (!i2c_adapter_compat_class) {
2077	retval = -ENOMEM;
2078	goto bus_err;
2079	}
2080	#endif
2081	retval = i2c_add_driver(&dummy_driver);
2082	if (retval)
2083	goto class_err;
2084
2085	if (IS_ENABLED(CONFIG_OF_DYNAMIC))
2086	WARN_ON(of_reconfig_notifier_register(&i2c_of_notifier));
2087	if (IS_ENABLED(CONFIG_ACPI))
2088	WARN_ON(acpi_reconfig_notifier_register(&i2c_acpi_notifier));
2089
2090	return `0`;
2091
2092	class_err:
2093	#ifdef CONFIG_I2C_COMPAT
2094	class_compat_unregister(cls: i2c_adapter_compat_class);
2095	bus_err:
2096	#endif
2097	is_registered = false;
2098	bus_unregister(bus: &i2c_bus_type);
2099	return retval;
2100	}
2101
2102	static void __exit i2c_exit(void)
2103	{
2104	if (IS_ENABLED(CONFIG_ACPI))
2105	WARN_ON(acpi_reconfig_notifier_unregister(&i2c_acpi_notifier));
2106	if (IS_ENABLED(CONFIG_OF_DYNAMIC))
2107	WARN_ON(of_reconfig_notifier_unregister(&i2c_of_notifier));
2108	i2c_del_driver(&dummy_driver);
2109	#ifdef CONFIG_I2C_COMPAT
2110	class_compat_unregister(cls: i2c_adapter_compat_class);
2111	#endif
2112	debugfs_remove_recursive(dentry: i2c_debugfs_root);
2113	bus_unregister(bus: &i2c_bus_type);
2114	tracepoint_synchronize_unregister();
2115	}
2116
2117	/ We must initialize early, because some subsystems register i2c drivers*
2118	* in subsys_initcall() code, but are linked (and initialized) before i2c.
2119	*/
2120	postcore_initcall(i2c_init);
2121	module_exit(i2c_exit);
2122
2123	/ ----------------------------------------------------*
2124	* the functional interface to the i2c busses.
2125	* ----------------------------------------------------
2126	*/
2127
2128	/ Check if val is exceeding the quirk IFF quirk is non 0 /
2129	#define i2c_quirk_exceeded(val, quirk) ((quirk) && ((val) > (quirk)))
2130
2131	static int i2c_quirk_error(struct i2c_adapter adap, struct* i2c_msg msg, char* *err_msg)
2132	{
2133	dev_err_ratelimited(&adap->dev, "adapter quirk: %s (addr 0x%04x, size %u, %s)\n",
2134	err_msg, msg->addr, msg->len,
2135	msg->flags & I2C_M_RD ? "read" : "write");
2136	return -EOPNOTSUPP;
2137	}
2138
2139	static int i2c_check_for_quirks(struct i2c_adapter adap, struct* i2c_msg msgs, int* num)
2140	{
2141	const struct i2c_adapter_quirks *q = adap->quirks;
2142	int max_num = q->max_num_msgs, i;
2143	bool do_len_check = true;
2144
2145	if (q->flags & I2C_AQ_COMB) {
2146	max_num = `2`;
2147
2148	/ special checks for combined messages /
2149	if (num == `2`) {
2150	if (q->flags & I2C_AQ_COMB_WRITE_FIRST && msgs[`0`].flags & I2C_M_RD)
2151	return i2c_quirk_error(adap, msg: &msgs[`0`], err_msg: "1st comb msg must be write");
2152
2153	if (q->flags & I2C_AQ_COMB_READ_SECOND && !(msgs[`1`].flags & I2C_M_RD))
2154	return i2c_quirk_error(adap, msg: &msgs[`1`], err_msg: "2nd comb msg must be read");
2155
2156	if (q->flags & I2C_AQ_COMB_SAME_ADDR && msgs[`0`].addr != msgs[`1`].addr)
2157	return i2c_quirk_error(adap, msg: &msgs[`0`], err_msg: "comb msg only to same addr");
2158
2159	if (i2c_quirk_exceeded(msgs[`0`].len, q->max_comb_1st_msg_len))
2160	return i2c_quirk_error(adap, msg: &msgs[`0`], err_msg: "msg too long");
2161
2162	if (i2c_quirk_exceeded(msgs[`1`].len, q->max_comb_2nd_msg_len))
2163	return i2c_quirk_error(adap, msg: &msgs[`1`], err_msg: "msg too long");
2164
2165	do_len_check = false;
2166	}
2167	}
2168
2169	if (i2c_quirk_exceeded(num, max_num))
2170	return i2c_quirk_error(adap, msg: &msgs[`0`], err_msg: "too many messages");
2171
2172	for (i = `0`; i < num; i++) {
2173	u16 len = msgs[i].len;
2174
2175	if (msgs[i].flags & I2C_M_RD) {
2176	if (do_len_check && i2c_quirk_exceeded(len, q->max_read_len))
2177	return i2c_quirk_error(adap, msg: &msgs[i], err_msg: "msg too long");
2178
2179	if (q->flags & I2C_AQ_NO_ZERO_LEN_READ && len == `0`)
2180	return i2c_quirk_error(adap, msg: &msgs[i], err_msg: "no zero length");
2181	} else {
2182	if (do_len_check && i2c_quirk_exceeded(len, q->max_write_len))
2183	return i2c_quirk_error(adap, msg: &msgs[i], err_msg: "msg too long");
2184
2185	if (q->flags & I2C_AQ_NO_ZERO_LEN_WRITE && len == `0`)
2186	return i2c_quirk_error(adap, msg: &msgs[i], err_msg: "no zero length");
2187	}
2188	}
2189
2190	return `0`;
2191	}
2192
2193	/**
2194	* __i2c_transfer - unlocked flavor of i2c_transfer
2195	* @adap: Handle to I2C bus
2196	* @msgs: One or more messages to execute before STOP is issued to
2197	* terminate the operation; each message begins with a START.
2198	* @num: Number of messages to be executed.
2199	*
2200	* Returns negative errno, else the number of messages executed.
2201	*
2202	* Adapter lock must be held when calling this function. No debug logging
2203	* takes place. adap->algo->master_xfer existence isn't checked.
2204	*/
2205	int __i2c_transfer(struct i2c_adapter adap, struct* i2c_msg msgs, int* num)
2206	{
2207	unsigned long orig_jiffies;
2208	int ret, try;
2209
2210	if (WARN_ON(!msgs \|\| num < `1`))
2211	return -EINVAL;
2212
2213	ret = __i2c_check_suspended(adap);
2214	if (ret)
2215	return ret;
2216
2217	if (adap->quirks && i2c_check_for_quirks(adap, msgs, num))
2218	return -EOPNOTSUPP;
2219
2220	/*
2221	* i2c_trace_msg_key gets enabled when tracepoint i2c_transfer gets
2222	* enabled. This is an efficient way of keeping the for-loop from
2223	* being executed when not needed.
2224	*/
2225	if (static_branch_unlikely(&i2c_trace_msg_key)) {
2226	int i;
2227	for (i = `0`; i < num; i++)
2228	if (msgs[i].flags & I2C_M_RD)
2229	trace_i2c_read(adap, msg: &msgs[i], num: i);
2230	else
2231	trace_i2c_write(adap, msg: &msgs[i], num: i);
2232	}
2233
2234	/ Retry automatically on arbitration loss /
2235	orig_jiffies = jiffies;
2236	for (ret = `0`, try = `0`; try <= adap->retries; try++) {
2237	if (i2c_in_atomic_xfer_mode() && adap->algo->master_xfer_atomic)
2238	ret = adap->algo->master_xfer_atomic(adap, msgs, num);
2239	else
2240	ret = adap->algo->master_xfer(adap, msgs, num);
2241
2242	if (ret != -EAGAIN)
2243	break;
2244	if (time_after(jiffies, orig_jiffies + adap->timeout))
2245	break;
2246	}
2247
2248	if (static_branch_unlikely(&i2c_trace_msg_key)) {
2249	int i;
2250	for (i = `0`; i < ret; i++)
2251	if (msgs[i].flags & I2C_M_RD)
2252	trace_i2c_reply(adap, msg: &msgs[i], num: i);
2253	trace_i2c_result(adap, num, ret);
2254	}
2255
2256	return ret;
2257	}
2258	EXPORT_SYMBOL(__i2c_transfer);
2259
2260	/**
2261	* i2c_transfer - execute a single or combined I2C message
2262	* @adap: Handle to I2C bus
2263	* @msgs: One or more messages to execute before STOP is issued to
2264	* terminate the operation; each message begins with a START.
2265	* @num: Number of messages to be executed.
2266	*
2267	* Returns negative errno, else the number of messages executed.
2268	*
2269	* Note that there is no requirement that each message be sent to
2270	* the same slave address, although that is the most common model.
2271	*/
2272	int i2c_transfer(struct i2c_adapter adap, struct* i2c_msg msgs, int* num)
2273	{
2274	int ret;
2275
2276	if (!adap->algo->master_xfer) {
2277	dev_dbg(&adap->dev, "I2C level transfers not supported\n");
2278	return -EOPNOTSUPP;
2279	}
2280
2281	/ REVISIT the fault reporting model here is weak:*
2282	*
2283	* - When we get an error after receiving N bytes from a slave,
2284	* there is no way to report "N".
2285	*
2286	* - When we get a NAK after transmitting N bytes to a slave,
2287	* there is no way to report "N" ... or to let the master
2288	* continue executing the rest of this combined message, if
2289	* that's the appropriate response.
2290	*
2291	* - When for example "num" is two and we successfully complete
2292	* the first message but get an error part way through the
2293	* second, it's unclear whether that should be reported as
2294	* one (discarding status on the second message) or errno
2295	* (discarding status on the first one).
2296	*/
2297	ret = __i2c_lock_bus_helper(adap);
2298	if (ret)
2299	return ret;
2300
2301	ret = __i2c_transfer(adap, msgs, num);
2302	i2c_unlock_bus(adapter: adap, I2C_LOCK_SEGMENT);
2303
2304	return ret;
2305	}
2306	EXPORT_SYMBOL(i2c_transfer);
2307
2308	/**
2309	* i2c_transfer_buffer_flags - issue a single I2C message transferring data
2310	* to/from a buffer
2311	* @client: Handle to slave device
2312	* @buf: Where the data is stored
2313	* @count: How many bytes to transfer, must be less than 64k since msg.len is u16
2314	* @flags: The flags to be used for the message, e.g. I2C_M_RD for reads
2315	*
2316	* Returns negative errno, or else the number of bytes transferred.
2317	*/
2318	int i2c_transfer_buffer_flags(const struct i2c_client client, char* *buf,
2319	int count, u16 flags)
2320	{
2321	int ret;
2322	struct i2c_msg msg = {
2323	.addr = client->addr,
2324	.flags = flags \| (client->flags & I2C_M_TEN),
2325	.len = count,
2326	.buf = buf,
2327	};
2328
2329	ret = i2c_transfer(client->adapter, &msg, `1`);
2330
2331	/*
2332	* If everything went ok (i.e. 1 msg transferred), return #bytes
2333	* transferred, else error code.
2334	*/
2335	return (ret == `1`) ? count : ret;
2336	}
2337	EXPORT_SYMBOL(i2c_transfer_buffer_flags);
2338
2339	/**
2340	* i2c_get_device_id - get manufacturer, part id and die revision of a device
2341	* @client: The device to query
2342	* @id: The queried information
2343	*
2344	* Returns negative errno on error, zero on success.
2345	*/
2346	int i2c_get_device_id(const struct i2c_client *client,
2347	struct i2c_device_identity *id)
2348	{
2349	struct i2c_adapter *adap = client->adapter;
2350	union i2c_smbus_data raw_id;
2351	int ret;
2352
2353	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
2354	return -EOPNOTSUPP;
2355
2356	raw_id.block[`0`] = `3`;
2357	ret = i2c_smbus_xfer(adapter: adap, I2C_ADDR_DEVICE_ID, flags: `0`,
2358	I2C_SMBUS_READ, command: client->addr << `1`,
2359	I2C_SMBUS_I2C_BLOCK_DATA, data: &raw_id);
2360	if (ret)
2361	return ret;
2362
2363	id->manufacturer_id = (raw_id.block[`1`] << `4`) \| (raw_id.block[`2`] >> `4`);
2364	id->part_id = ((raw_id.block[`2`] & `0xf`) << `5`) \| (raw_id.block[`3`] >> `3`);
2365	id->die_revision = raw_id.block[`3`] & `0x7`;
2366	return `0`;
2367	}
2368	EXPORT_SYMBOL_GPL(i2c_get_device_id);
2369
2370	/**
2371	* i2c_client_get_device_id - get the driver match table entry of a device
2372	* @client: the device to query. The device must be bound to a driver
2373	*
2374	* Returns a pointer to the matching entry if found, NULL otherwise.
2375	*/
2376	const struct i2c_device_id i2c_client_get_device_id(const* struct i2c_client *client)
2377	{
2378	const struct i2c_driver *drv = to_i2c_driver(client->dev.driver);
2379
2380	return i2c_match_id(drv->id_table, client);
2381	}
2382	EXPORT_SYMBOL_GPL(i2c_client_get_device_id);
2383
2384	/ ----------------------------------------------------*
2385	* the i2c address scanning function
2386	* Will not work for 10-bit addresses!
2387	* ----------------------------------------------------
2388	*/
2389
2390	/*
2391	* Legacy default probe function, mostly relevant for SMBus. The default
2392	* probe method is a quick write, but it is known to corrupt the 24RF08
2393	* EEPROMs due to a state machine bug, and could also irreversibly
2394	* write-protect some EEPROMs, so for address ranges 0x30-0x37 and 0x50-0x5f,
2395	* we use a short byte read instead. Also, some bus drivers don't implement
2396	* quick write, so we fallback to a byte read in that case too.
2397	* On x86, there is another special case for FSC hardware monitoring chips,
2398	* which want regular byte reads (address 0x73.) Fortunately, these are the
2399	* only known chips using this I2C address on PC hardware.
2400	* Returns 1 if probe succeeded, 0 if not.
2401	*/
2402	static int i2c_default_probe(struct i2c_adapter adap, unsigned* short addr)
2403	{
2404	int err;
2405	union i2c_smbus_data dummy;
2406
2407	#ifdef CONFIG_X86
2408	if (addr == `0x73` && (adap->class & I2C_CLASS_HWMON)
2409	&& i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE_DATA))
2410	err = i2c_smbus_xfer(adapter: adap, addr, flags: `0`, I2C_SMBUS_READ, command: `0`,
2411	I2C_SMBUS_BYTE_DATA, data: &dummy);
2412	else
2413	#endif
2414	if (!((addr & ~`0x07`) == `0x30` \|\| (addr & ~`0x0f`) == `0x50`)
2415	&& i2c_check_functionality(adap, I2C_FUNC_SMBUS_QUICK))
2416	err = i2c_smbus_xfer(adapter: adap, addr, flags: `0`, I2C_SMBUS_WRITE, command: `0`,
2417	I2C_SMBUS_QUICK, NULL);
2418	else if (i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE))
2419	err = i2c_smbus_xfer(adapter: adap, addr, flags: `0`, I2C_SMBUS_READ, command: `0`,
2420	I2C_SMBUS_BYTE, data: &dummy);
2421	else {
2422	dev_warn(&adap->dev, "No suitable probing method supported for address 0x%02X\n",
2423	addr);
2424	err = -EOPNOTSUPP;
2425	}
2426
2427	return err >= `0`;
2428	}
2429
2430	static int i2c_detect_address(struct i2c_client *temp_client,
2431	struct i2c_driver *driver)
2432	{
2433	struct i2c_board_info info;
2434	struct i2c_adapter *adapter = temp_client->adapter;
2435	int addr = temp_client->addr;
2436	int err;
2437
2438	/ Make sure the address is valid /
2439	err = i2c_check_7bit_addr_validity_strict(addr);
2440	if (err) {
2441	dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n",
2442	addr);
2443	return err;
2444	}
2445
2446	/ Skip if already in use (7 bit, no need to encode flags) /
2447	if (i2c_check_addr_busy(adapter, addr))
2448	return `0`;
2449
2450	/ Make sure there is something at this address /
2451	if (!i2c_default_probe(adap: adapter, addr))
2452	return `0`;
2453
2454	/ Finally call the custom detection function /
2455	memset(&info, `0`, sizeof(struct i2c_board_info));
2456	info.addr = addr;
2457	err = driver->detect(temp_client, &info);
2458	if (err) {
2459	/ -ENODEV is returned if the detection fails. We catch it*
2460	here as this isn't an error. /*
2461	return err == -ENODEV ? `0` : err;
2462	}
2463
2464	/ Consistency check /
2465	if (info.type[`0`] == `'\0'`) {
2466	dev_err(&adapter->dev,
2467	"%s detection function provided no name for 0x%x\n",
2468	driver->driver.name, addr);
2469	} else {
2470	struct i2c_client *client;
2471
2472	/ Detection succeeded, instantiate the device /
2473	if (adapter->class & I2C_CLASS_DEPRECATED)
2474	dev_warn(&adapter->dev,
2475	"This adapter will soon drop class based instantiation of devices. "
2476	"Please make sure client 0x%02x gets instantiated by other means. "
2477	"Check 'Documentation/i2c/instantiating-devices.rst' for details.\n",
2478	info.addr);
2479
2480	dev_dbg(&adapter->dev, "Creating %s at 0x%02x\n",
2481	info.type, info.addr);
2482	client = i2c_new_client_device(adapter, &info);
2483	if (!IS_ERR(ptr: client))
2484	list_add_tail(new: &client->detected, head: &driver->clients);
2485	else
2486	dev_err(&adapter->dev, "Failed creating %s at 0x%02x\n",
2487	info.type, info.addr);
2488	}
2489	return `0`;
2490	}
2491
2492	static int i2c_detect(struct i2c_adapter adapter, struct* i2c_driver *driver)
2493	{
2494	const unsigned short *address_list;
2495	struct i2c_client *temp_client;
2496	int i, err = `0`;
2497
2498	address_list = driver->address_list;
2499	if (!driver->detect \|\| !address_list)
2500	return `0`;
2501
2502	/ Warn that the adapter lost class based instantiation /
2503	if (adapter->class == I2C_CLASS_DEPRECATED) {
2504	dev_dbg(&adapter->dev,
2505	"This adapter dropped support for I2C classes and won't auto-detect %s devices anymore. "
2506	"If you need it, check 'Documentation/i2c/instantiating-devices.rst' for alternatives.\n",
2507	driver->driver.name);
2508	return `0`;
2509	}
2510
2511	/ Stop here if the classes do not match /
2512	if (!(adapter->class & driver->class))
2513	return `0`;
2514
2515	/ Set up a temporary client to help detect callback /
2516	temp_client = kzalloc(size: sizeof(struct i2c_client), GFP_KERNEL);
2517	if (!temp_client)
2518	return -ENOMEM;
2519	temp_client->adapter = adapter;
2520
2521	for (i = `0`; address_list[i] != I2C_CLIENT_END; i += `1`) {
2522	dev_dbg(&adapter->dev,
2523	"found normal entry for adapter %d, addr 0x%02x\n",
2524	i2c_adapter_id(adapter), address_list[i]);
2525	temp_client->addr = address_list[i];
2526	err = i2c_detect_address(temp_client, driver);
2527	if (unlikely(err))
2528	break;
2529	}
2530
2531	kfree(objp: temp_client);
2532	return err;
2533	}
2534
2535	int i2c_probe_func_quick_read(struct i2c_adapter adap, unsigned* short addr)
2536	{
2537	return i2c_smbus_xfer(adapter: adap, addr, flags: `0`, I2C_SMBUS_READ, command: `0`,
2538	I2C_SMBUS_QUICK, NULL) >= `0`;
2539	}
2540	EXPORT_SYMBOL_GPL(i2c_probe_func_quick_read);
2541
2542	struct i2c_client *
2543	i2c_new_scanned_device(struct i2c_adapter *adap,
2544	struct i2c_board_info *info,
2545	unsigned short const *addr_list,
2546	int (probe)(struct* i2c_adapter adap, unsigned* short addr))
2547	{
2548	int i;
2549
2550	if (!probe)
2551	probe = i2c_default_probe;
2552
2553	for (i = `0`; addr_list[i] != I2C_CLIENT_END; i++) {
2554	/ Check address validity /
2555	if (i2c_check_7bit_addr_validity_strict(addr: addr_list[i]) < `0`) {
2556	dev_warn(&adap->dev, "Invalid 7-bit address 0x%02x\n",
2557	addr_list[i]);
2558	continue;
2559	}
2560
2561	/ Check address availability (7 bit, no need to encode flags) /
2562	if (i2c_check_addr_busy(adapter: adap, addr: addr_list[i])) {
2563	dev_dbg(&adap->dev,
2564	"Address 0x%02x already in use, not probing\n",
2565	addr_list[i]);
2566	continue;
2567	}
2568
2569	/ Test address responsiveness /
2570	if (probe(adap, addr_list[i]))
2571	break;
2572	}
2573
2574	if (addr_list[i] == I2C_CLIENT_END) {
2575	dev_dbg(&adap->dev, "Probing failed, no device found\n");
2576	return ERR_PTR(error: -ENODEV);
2577	}
2578
2579	info->addr = addr_list[i];
2580	return i2c_new_client_device(adap, info);
2581	}
2582	EXPORT_SYMBOL_GPL(i2c_new_scanned_device);
2583
2584	struct i2c_adapter i2c_get_adapter(int* nr)
2585	{
2586	struct i2c_adapter *adapter;
2587
2588	mutex_lock(&core_lock);
2589	adapter = idr_find(&i2c_adapter_idr, id: nr);
2590	if (!adapter)
2591	goto exit;
2592
2593	if (try_module_get(module: adapter->owner))
2594	get_device(dev: &adapter->dev);
2595	else
2596	adapter = NULL;
2597
2598	exit:
2599	mutex_unlock(lock: &core_lock);
2600	return adapter;
2601	}
2602	EXPORT_SYMBOL(i2c_get_adapter);
2603
2604	void i2c_put_adapter(struct i2c_adapter *adap)
2605	{
2606	if (!adap)
2607	return;
2608
2609	module_put(module: adap->owner);
2610	/ Should be last, otherwise we risk use-after-free with 'adap' /
2611	put_device(dev: &adap->dev);
2612	}
2613	EXPORT_SYMBOL(i2c_put_adapter);
2614
2615	/**
2616	* i2c_get_dma_safe_msg_buf() - get a DMA safe buffer for the given i2c_msg
2617	* @msg: the message to be checked
2618	* @threshold: the minimum number of bytes for which using DMA makes sense.
2619	* Should at least be 1.
2620	*
2621	* Return: NULL if a DMA safe buffer was not obtained. Use msg->buf with PIO.
2622	* Or a valid pointer to be used with DMA. After use, release it by
2623	* calling i2c_put_dma_safe_msg_buf().
2624	*
2625	* This function must only be called from process context!
2626	*/
2627	u8 i2c_get_dma_safe_msg_buf(struct* i2c_msg msg, unsigned* int threshold)
2628	{
2629	/ also skip 0-length msgs for bogus thresholds of 0 /
2630	if (!threshold)
2631	pr_debug("DMA buffer for addr=0x%02x with length 0 is bogus\n",
2632	msg->addr);
2633	if (msg->len < threshold \|\| msg->len == `0`)
2634	return NULL;
2635
2636	if (msg->flags & I2C_M_DMA_SAFE)
2637	return msg->buf;
2638
2639	pr_debug("using bounce buffer for addr=0x%02x, len=%d\n",
2640	msg->addr, msg->len);
2641
2642	if (msg->flags & I2C_M_RD)
2643	return kzalloc(size: msg->len, GFP_KERNEL);
2644	else
2645	return kmemdup(p: msg->buf, size: msg->len, GFP_KERNEL);
2646	}
2647	EXPORT_SYMBOL_GPL(i2c_get_dma_safe_msg_buf);
2648
2649	/**
2650	* i2c_put_dma_safe_msg_buf - release DMA safe buffer and sync with i2c_msg
2651	* @buf: the buffer obtained from i2c_get_dma_safe_msg_buf(). May be NULL.
2652	* @msg: the message which the buffer corresponds to
2653	* @xferred: bool saying if the message was transferred
2654	*/
2655	void i2c_put_dma_safe_msg_buf(u8 buf, struct* i2c_msg *msg, bool xferred)
2656	{
2657	if (!buf \|\| buf == msg->buf)
2658	return;
2659
2660	if (xferred && msg->flags & I2C_M_RD)
2661	memcpy(msg->buf, buf, msg->len);
2662
2663	kfree(objp: buf);
2664	}
2665	EXPORT_SYMBOL_GPL(i2c_put_dma_safe_msg_buf);
2666
2667	MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
2668	MODULE_DESCRIPTION("I2C-Bus main module");
2669	MODULE_LICENSE("GPL");
2670

source code of linux/drivers/i2c/i2c-core-base.c