1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * i2c-smbus.c - SMBus extensions to the I2C protocol |
4 | * |
5 | * Copyright (C) 2008 David Brownell |
6 | * Copyright (C) 2010-2019 Jean Delvare <jdelvare@suse.de> |
7 | */ |
8 | |
9 | #include <linux/device.h> |
10 | #include <linux/dmi.h> |
11 | #include <linux/i2c.h> |
12 | #include <linux/i2c-smbus.h> |
13 | #include <linux/interrupt.h> |
14 | #include <linux/kernel.h> |
15 | #include <linux/module.h> |
16 | #include <linux/property.h> |
17 | #include <linux/slab.h> |
18 | #include <linux/workqueue.h> |
19 | |
20 | struct i2c_smbus_alert { |
21 | struct work_struct alert; |
22 | struct i2c_client *ara; /* Alert response address */ |
23 | }; |
24 | |
25 | struct alert_data { |
26 | unsigned short addr; |
27 | enum i2c_alert_protocol type; |
28 | unsigned int data; |
29 | }; |
30 | |
31 | /* If this is the alerting device, notify its driver */ |
32 | static int smbus_do_alert(struct device *dev, void *addrp) |
33 | { |
34 | struct i2c_client *client = i2c_verify_client(dev); |
35 | struct alert_data *data = addrp; |
36 | struct i2c_driver *driver; |
37 | |
38 | if (!client || client->addr != data->addr) |
39 | return 0; |
40 | if (client->flags & I2C_CLIENT_TEN) |
41 | return 0; |
42 | |
43 | /* |
44 | * Drivers should either disable alerts, or provide at least |
45 | * a minimal handler. Lock so the driver won't change. |
46 | */ |
47 | device_lock(dev); |
48 | if (client->dev.driver) { |
49 | driver = to_i2c_driver(client->dev.driver); |
50 | if (driver->alert) |
51 | driver->alert(client, data->type, data->data); |
52 | else |
53 | dev_warn(&client->dev, "no driver alert()!\n" ); |
54 | } else |
55 | dev_dbg(&client->dev, "alert with no driver\n" ); |
56 | device_unlock(dev); |
57 | |
58 | /* Stop iterating after we find the device */ |
59 | return -EBUSY; |
60 | } |
61 | |
62 | /* |
63 | * The alert IRQ handler needs to hand work off to a task which can issue |
64 | * SMBus calls, because those sleeping calls can't be made in IRQ context. |
65 | */ |
66 | static irqreturn_t smbus_alert(int irq, void *d) |
67 | { |
68 | struct i2c_smbus_alert *alert = d; |
69 | struct i2c_client *ara; |
70 | |
71 | ara = alert->ara; |
72 | |
73 | for (;;) { |
74 | s32 status; |
75 | struct alert_data data; |
76 | |
77 | /* |
78 | * Devices with pending alerts reply in address order, low |
79 | * to high, because of slave transmit arbitration. After |
80 | * responding, an SMBus device stops asserting SMBALERT#. |
81 | * |
82 | * Note that SMBus 2.0 reserves 10-bit addresses for future |
83 | * use. We neither handle them, nor try to use PEC here. |
84 | */ |
85 | status = i2c_smbus_read_byte(client: ara); |
86 | if (status < 0) |
87 | break; |
88 | |
89 | data.data = status & 1; |
90 | data.addr = status >> 1; |
91 | data.type = I2C_PROTOCOL_SMBUS_ALERT; |
92 | |
93 | dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n" , |
94 | data.addr, data.data); |
95 | |
96 | /* Notify driver for the device which issued the alert */ |
97 | device_for_each_child(dev: &ara->adapter->dev, data: &data, |
98 | fn: smbus_do_alert); |
99 | } |
100 | |
101 | return IRQ_HANDLED; |
102 | } |
103 | |
104 | static void smbalert_work(struct work_struct *work) |
105 | { |
106 | struct i2c_smbus_alert *alert; |
107 | |
108 | alert = container_of(work, struct i2c_smbus_alert, alert); |
109 | |
110 | smbus_alert(irq: 0, d: alert); |
111 | |
112 | } |
113 | |
114 | /* Setup SMBALERT# infrastructure */ |
115 | static int smbalert_probe(struct i2c_client *ara) |
116 | { |
117 | struct i2c_smbus_alert_setup *setup = dev_get_platdata(dev: &ara->dev); |
118 | struct i2c_smbus_alert *alert; |
119 | struct i2c_adapter *adapter = ara->adapter; |
120 | int res, irq; |
121 | |
122 | alert = devm_kzalloc(dev: &ara->dev, size: sizeof(struct i2c_smbus_alert), |
123 | GFP_KERNEL); |
124 | if (!alert) |
125 | return -ENOMEM; |
126 | |
127 | if (setup) { |
128 | irq = setup->irq; |
129 | } else { |
130 | irq = fwnode_irq_get_byname(dev_fwnode(adapter->dev.parent), |
131 | name: "smbus_alert" ); |
132 | if (irq <= 0) |
133 | return irq; |
134 | } |
135 | |
136 | INIT_WORK(&alert->alert, smbalert_work); |
137 | alert->ara = ara; |
138 | |
139 | if (irq > 0) { |
140 | res = devm_request_threaded_irq(dev: &ara->dev, irq, |
141 | NULL, thread_fn: smbus_alert, |
142 | IRQF_SHARED | IRQF_ONESHOT, |
143 | devname: "smbus_alert" , dev_id: alert); |
144 | if (res) |
145 | return res; |
146 | } |
147 | |
148 | i2c_set_clientdata(client: ara, data: alert); |
149 | dev_info(&adapter->dev, "supports SMBALERT#\n" ); |
150 | |
151 | return 0; |
152 | } |
153 | |
154 | /* IRQ and memory resources are managed so they are freed automatically */ |
155 | static void smbalert_remove(struct i2c_client *ara) |
156 | { |
157 | struct i2c_smbus_alert *alert = i2c_get_clientdata(client: ara); |
158 | |
159 | cancel_work_sync(work: &alert->alert); |
160 | } |
161 | |
162 | static const struct i2c_device_id smbalert_ids[] = { |
163 | { "smbus_alert" , 0 }, |
164 | { /* LIST END */ } |
165 | }; |
166 | MODULE_DEVICE_TABLE(i2c, smbalert_ids); |
167 | |
168 | static struct i2c_driver smbalert_driver = { |
169 | .driver = { |
170 | .name = "smbus_alert" , |
171 | }, |
172 | .probe = smbalert_probe, |
173 | .remove = smbalert_remove, |
174 | .id_table = smbalert_ids, |
175 | }; |
176 | |
177 | /** |
178 | * i2c_handle_smbus_alert - Handle an SMBus alert |
179 | * @ara: the ARA client on the relevant adapter |
180 | * Context: can't sleep |
181 | * |
182 | * Helper function to be called from an I2C bus driver's interrupt |
183 | * handler. It will schedule the alert work, in turn calling the |
184 | * corresponding I2C device driver's alert function. |
185 | * |
186 | * It is assumed that ara is a valid i2c client previously returned by |
187 | * i2c_new_smbus_alert_device(). |
188 | */ |
189 | int i2c_handle_smbus_alert(struct i2c_client *ara) |
190 | { |
191 | struct i2c_smbus_alert *alert = i2c_get_clientdata(client: ara); |
192 | |
193 | return schedule_work(work: &alert->alert); |
194 | } |
195 | EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert); |
196 | |
197 | module_i2c_driver(smbalert_driver); |
198 | |
199 | #if IS_ENABLED(CONFIG_I2C_SLAVE) |
200 | #define SMBUS_HOST_NOTIFY_LEN 3 |
201 | struct i2c_slave_host_notify_status { |
202 | u8 index; |
203 | u8 addr; |
204 | }; |
205 | |
206 | static int i2c_slave_host_notify_cb(struct i2c_client *client, |
207 | enum i2c_slave_event event, u8 *val) |
208 | { |
209 | struct i2c_slave_host_notify_status *status = client->dev.platform_data; |
210 | |
211 | switch (event) { |
212 | case I2C_SLAVE_WRITE_RECEIVED: |
213 | /* We only retrieve the first byte received (addr) |
214 | * since there is currently no support to retrieve the data |
215 | * parameter from the client. |
216 | */ |
217 | if (status->index == 0) |
218 | status->addr = *val; |
219 | if (status->index < U8_MAX) |
220 | status->index++; |
221 | break; |
222 | case I2C_SLAVE_STOP: |
223 | if (status->index == SMBUS_HOST_NOTIFY_LEN) |
224 | i2c_handle_smbus_host_notify(adap: client->adapter, |
225 | addr: status->addr); |
226 | fallthrough; |
227 | case I2C_SLAVE_WRITE_REQUESTED: |
228 | status->index = 0; |
229 | break; |
230 | case I2C_SLAVE_READ_REQUESTED: |
231 | case I2C_SLAVE_READ_PROCESSED: |
232 | *val = 0xff; |
233 | break; |
234 | } |
235 | |
236 | return 0; |
237 | } |
238 | |
239 | /** |
240 | * i2c_new_slave_host_notify_device - get a client for SMBus host-notify support |
241 | * @adapter: the target adapter |
242 | * Context: can sleep |
243 | * |
244 | * Setup handling of the SMBus host-notify protocol on a given I2C bus segment. |
245 | * |
246 | * Handling is done by creating a device and its callback and handling data |
247 | * received via the SMBus host-notify address (0x8) |
248 | * |
249 | * This returns the client, which should be ultimately freed using |
250 | * i2c_free_slave_host_notify_device(); or an ERRPTR to indicate an error. |
251 | */ |
252 | struct i2c_client *i2c_new_slave_host_notify_device(struct i2c_adapter *adapter) |
253 | { |
254 | struct i2c_board_info host_notify_board_info = { |
255 | I2C_BOARD_INFO("smbus_host_notify" , 0x08), |
256 | .flags = I2C_CLIENT_SLAVE, |
257 | }; |
258 | struct i2c_slave_host_notify_status *status; |
259 | struct i2c_client *client; |
260 | int ret; |
261 | |
262 | status = kzalloc(size: sizeof(struct i2c_slave_host_notify_status), |
263 | GFP_KERNEL); |
264 | if (!status) |
265 | return ERR_PTR(error: -ENOMEM); |
266 | |
267 | host_notify_board_info.platform_data = status; |
268 | |
269 | client = i2c_new_client_device(adap: adapter, info: &host_notify_board_info); |
270 | if (IS_ERR(ptr: client)) { |
271 | kfree(objp: status); |
272 | return client; |
273 | } |
274 | |
275 | ret = i2c_slave_register(client, slave_cb: i2c_slave_host_notify_cb); |
276 | if (ret) { |
277 | i2c_unregister_device(client); |
278 | kfree(objp: status); |
279 | return ERR_PTR(error: ret); |
280 | } |
281 | |
282 | return client; |
283 | } |
284 | EXPORT_SYMBOL_GPL(i2c_new_slave_host_notify_device); |
285 | |
286 | /** |
287 | * i2c_free_slave_host_notify_device - free the client for SMBus host-notify |
288 | * support |
289 | * @client: the client to free |
290 | * Context: can sleep |
291 | * |
292 | * Free the i2c_client allocated via i2c_new_slave_host_notify_device |
293 | */ |
294 | void i2c_free_slave_host_notify_device(struct i2c_client *client) |
295 | { |
296 | if (IS_ERR_OR_NULL(ptr: client)) |
297 | return; |
298 | |
299 | i2c_slave_unregister(client); |
300 | kfree(objp: client->dev.platform_data); |
301 | i2c_unregister_device(client); |
302 | } |
303 | EXPORT_SYMBOL_GPL(i2c_free_slave_host_notify_device); |
304 | #endif |
305 | |
306 | /* |
307 | * SPD is not part of SMBus but we include it here for convenience as the |
308 | * target systems are the same. |
309 | * Restrictions to automatic SPD instantiation: |
310 | * - Only works if all filled slots have the same memory type |
311 | * - Only works for DDR2, DDR3 and DDR4 for now |
312 | * - Only works on systems with 1 to 4 memory slots |
313 | */ |
314 | #if IS_ENABLED(CONFIG_DMI) |
315 | void i2c_register_spd(struct i2c_adapter *adap) |
316 | { |
317 | int n, slot_count = 0, dimm_count = 0; |
318 | u16 handle; |
319 | u8 common_mem_type = 0x0, mem_type; |
320 | u64 mem_size; |
321 | const char *name; |
322 | |
323 | while ((handle = dmi_memdev_handle(slot: slot_count)) != 0xffff) { |
324 | slot_count++; |
325 | |
326 | /* Skip empty slots */ |
327 | mem_size = dmi_memdev_size(handle); |
328 | if (!mem_size) |
329 | continue; |
330 | |
331 | /* Skip undefined memory type */ |
332 | mem_type = dmi_memdev_type(handle); |
333 | if (mem_type <= 0x02) /* Invalid, Other, Unknown */ |
334 | continue; |
335 | |
336 | if (!common_mem_type) { |
337 | /* First filled slot */ |
338 | common_mem_type = mem_type; |
339 | } else { |
340 | /* Check that all filled slots have the same type */ |
341 | if (mem_type != common_mem_type) { |
342 | dev_warn(&adap->dev, |
343 | "Different memory types mixed, not instantiating SPD\n" ); |
344 | return; |
345 | } |
346 | } |
347 | dimm_count++; |
348 | } |
349 | |
350 | /* No useful DMI data, bail out */ |
351 | if (!dimm_count) |
352 | return; |
353 | |
354 | dev_info(&adap->dev, "%d/%d memory slots populated (from DMI)\n" , |
355 | dimm_count, slot_count); |
356 | |
357 | if (slot_count > 4) { |
358 | dev_warn(&adap->dev, |
359 | "Systems with more than 4 memory slots not supported yet, not instantiating SPD\n" ); |
360 | return; |
361 | } |
362 | |
363 | /* |
364 | * Memory types could be found at section 7.18.2 (Memory Device — Type), table 78 |
365 | * https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.6.0.pdf |
366 | */ |
367 | switch (common_mem_type) { |
368 | case 0x12: /* DDR */ |
369 | case 0x13: /* DDR2 */ |
370 | case 0x18: /* DDR3 */ |
371 | case 0x1B: /* LPDDR */ |
372 | case 0x1C: /* LPDDR2 */ |
373 | case 0x1D: /* LPDDR3 */ |
374 | name = "spd" ; |
375 | break; |
376 | case 0x1A: /* DDR4 */ |
377 | case 0x1E: /* LPDDR4 */ |
378 | name = "ee1004" ; |
379 | break; |
380 | default: |
381 | dev_info(&adap->dev, |
382 | "Memory type 0x%02x not supported yet, not instantiating SPD\n" , |
383 | common_mem_type); |
384 | return; |
385 | } |
386 | |
387 | /* |
388 | * We don't know in which slots the memory modules are. We could |
389 | * try to guess from the slot names, but that would be rather complex |
390 | * and unreliable, so better probe all possible addresses until we |
391 | * have found all memory modules. |
392 | */ |
393 | for (n = 0; n < slot_count && dimm_count; n++) { |
394 | struct i2c_board_info info; |
395 | unsigned short addr_list[2]; |
396 | |
397 | memset(&info, 0, sizeof(struct i2c_board_info)); |
398 | strscpy(p: info.type, q: name, I2C_NAME_SIZE); |
399 | addr_list[0] = 0x50 + n; |
400 | addr_list[1] = I2C_CLIENT_END; |
401 | |
402 | if (!IS_ERR(ptr: i2c_new_scanned_device(adap, info: &info, addr_list, NULL))) { |
403 | dev_info(&adap->dev, |
404 | "Successfully instantiated SPD at 0x%hx\n" , |
405 | addr_list[0]); |
406 | dimm_count--; |
407 | } |
408 | } |
409 | } |
410 | EXPORT_SYMBOL_GPL(i2c_register_spd); |
411 | #endif |
412 | |
413 | MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>" ); |
414 | MODULE_DESCRIPTION("SMBus protocol extensions support" ); |
415 | MODULE_LICENSE("GPL" ); |
416 | |