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