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c942fddf | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
b5527a77 JD |
2 | /* |
3 | * i2c-smbus.c - SMBus extensions to the I2C protocol | |
4 | * | |
5 | * Copyright (C) 2008 David Brownell | |
5ace6085 | 6 | * Copyright (C) 2010-2019 Jean Delvare <jdelvare@suse.de> |
b5527a77 JD |
7 | */ |
8 | ||
b5527a77 | 9 | #include <linux/device.h> |
5ace6085 | 10 | #include <linux/dmi.h> |
b5527a77 JD |
11 | #include <linux/i2c.h> |
12 | #include <linux/i2c-smbus.h> | |
62c874ab WS |
13 | #include <linux/interrupt.h> |
14 | #include <linux/kernel.h> | |
15 | #include <linux/module.h> | |
a263a840 | 16 | #include <linux/property.h> |
5a0e3ad6 | 17 | #include <linux/slab.h> |
62c874ab | 18 | #include <linux/workqueue.h> |
b5527a77 JD |
19 | |
20 | struct i2c_smbus_alert { | |
b5527a77 JD |
21 | struct work_struct alert; |
22 | struct i2c_client *ara; /* Alert response address */ | |
23 | }; | |
24 | ||
25 | struct alert_data { | |
26 | unsigned short addr; | |
e456cd37 BT |
27 | enum i2c_alert_protocol type; |
28 | unsigned int data; | |
b5527a77 JD |
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; | |
0acc2b32 | 36 | struct i2c_driver *driver; |
b5527a77 JD |
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 | |
0acc2b32 | 45 | * a minimal handler. Lock so the driver won't change. |
b5527a77 | 46 | */ |
f635a1e7 | 47 | device_lock(dev); |
0acc2b32 LPC |
48 | if (client->dev.driver) { |
49 | driver = to_i2c_driver(client->dev.driver); | |
50 | if (driver->alert) | |
e456cd37 | 51 | driver->alert(client, data->type, data->data); |
b5527a77 JD |
52 | else |
53 | dev_warn(&client->dev, "no driver alert()!\n"); | |
54 | } else | |
55 | dev_dbg(&client->dev, "alert with no driver\n"); | |
f635a1e7 | 56 | device_unlock(dev); |
b5527a77 JD |
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 | */ | |
9b9f2b8b | 66 | static irqreturn_t smbus_alert(int irq, void *d) |
b5527a77 | 67 | { |
9b9f2b8b | 68 | struct i2c_smbus_alert *alert = d; |
b5527a77 | 69 | struct i2c_client *ara; |
b5527a77 | 70 | |
b5527a77 JD |
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 | * | |
edc9102a | 82 | * Note that SMBus 2.0 reserves 10-bit addresses for future |
b5527a77 JD |
83 | * use. We neither handle them, nor try to use PEC here. |
84 | */ | |
85 | status = i2c_smbus_read_byte(ara); | |
86 | if (status < 0) | |
87 | break; | |
88 | ||
e456cd37 | 89 | data.data = status & 1; |
b5527a77 | 90 | data.addr = status >> 1; |
e456cd37 | 91 | data.type = I2C_PROTOCOL_SMBUS_ALERT; |
b5527a77 | 92 | |
b5527a77 | 93 | dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n", |
e456cd37 | 94 | data.addr, data.data); |
b5527a77 JD |
95 | |
96 | /* Notify driver for the device which issued the alert */ | |
97 | device_for_each_child(&ara->adapter->dev, &data, | |
98 | smbus_do_alert); | |
b5527a77 JD |
99 | } |
100 | ||
9b9f2b8b | 101 | return IRQ_HANDLED; |
b5527a77 JD |
102 | } |
103 | ||
9b9f2b8b | 104 | static void smbalert_work(struct work_struct *work) |
b5527a77 | 105 | { |
9b9f2b8b PR |
106 | struct i2c_smbus_alert *alert; |
107 | ||
108 | alert = container_of(work, struct i2c_smbus_alert, alert); | |
b5527a77 | 109 | |
9b9f2b8b | 110 | smbus_alert(0, alert); |
b5527a77 | 111 | |
b5527a77 JD |
112 | } |
113 | ||
114 | /* Setup SMBALERT# infrastructure */ | |
a00f6d37 | 115 | static int smbalert_probe(struct i2c_client *ara) |
b5527a77 | 116 | { |
6d4028c6 | 117 | struct i2c_smbus_alert_setup *setup = dev_get_platdata(&ara->dev); |
b5527a77 JD |
118 | struct i2c_smbus_alert *alert; |
119 | struct i2c_adapter *adapter = ara->adapter; | |
9b9f2b8b | 120 | int res, irq; |
b5527a77 | 121 | |
71b57845 JL |
122 | alert = devm_kzalloc(&ara->dev, sizeof(struct i2c_smbus_alert), |
123 | GFP_KERNEL); | |
b5527a77 JD |
124 | if (!alert) |
125 | return -ENOMEM; | |
126 | ||
69d17246 PR |
127 | if (setup) { |
128 | irq = setup->irq; | |
129 | } else { | |
a263a840 A |
130 | irq = fwnode_irq_get_byname(dev_fwnode(adapter->dev.parent), |
131 | "smbus_alert"); | |
69d17246 PR |
132 | if (irq <= 0) |
133 | return irq; | |
134 | } | |
135 | ||
9b9f2b8b | 136 | INIT_WORK(&alert->alert, smbalert_work); |
b5527a77 JD |
137 | alert->ara = ara; |
138 | ||
9b9f2b8b PR |
139 | if (irq > 0) { |
140 | res = devm_request_threaded_irq(&ara->dev, irq, | |
141 | NULL, smbus_alert, | |
142 | IRQF_SHARED | IRQF_ONESHOT, | |
143 | "smbus_alert", alert); | |
71b57845 | 144 | if (res) |
b5527a77 | 145 | return res; |
b5527a77 JD |
146 | } |
147 | ||
148 | i2c_set_clientdata(ara, alert); | |
9b9f2b8b | 149 | dev_info(&adapter->dev, "supports SMBALERT#\n"); |
b5527a77 JD |
150 | |
151 | return 0; | |
152 | } | |
153 | ||
71b57845 | 154 | /* IRQ and memory resources are managed so they are freed automatically */ |
ed5c2f5f | 155 | static void smbalert_remove(struct i2c_client *ara) |
b5527a77 JD |
156 | { |
157 | struct i2c_smbus_alert *alert = i2c_get_clientdata(ara); | |
158 | ||
159 | cancel_work_sync(&alert->alert); | |
b5527a77 JD |
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 | }, | |
834a9dc4 | 172 | .probe = smbalert_probe, |
b5527a77 JD |
173 | .remove = smbalert_remove, |
174 | .id_table = smbalert_ids, | |
175 | }; | |
176 | ||
b5527a77 JD |
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 | |
ed680522 | 187 | * i2c_new_smbus_alert_device(). |
b5527a77 JD |
188 | */ |
189 | int i2c_handle_smbus_alert(struct i2c_client *ara) | |
190 | { | |
191 | struct i2c_smbus_alert *alert = i2c_get_clientdata(ara); | |
192 | ||
193 | return schedule_work(&alert->alert); | |
194 | } | |
195 | EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert); | |
196 | ||
fda2f4af | 197 | module_i2c_driver(smbalert_driver); |
b5527a77 | 198 | |
2a71593d AV |
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(client->adapter, | |
225 | 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(sizeof(struct i2c_slave_host_notify_status), | |
263 | GFP_KERNEL); | |
264 | if (!status) | |
265 | return ERR_PTR(-ENOMEM); | |
266 | ||
267 | host_notify_board_info.platform_data = status; | |
268 | ||
269 | client = i2c_new_client_device(adapter, &host_notify_board_info); | |
270 | if (IS_ERR(client)) { | |
271 | kfree(status); | |
272 | return client; | |
273 | } | |
274 | ||
275 | ret = i2c_slave_register(client, i2c_slave_host_notify_cb); | |
276 | if (ret) { | |
277 | i2c_unregister_device(client); | |
278 | kfree(status); | |
279 | return ERR_PTR(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(client)) | |
297 | return; | |
298 | ||
299 | i2c_slave_unregister(client); | |
300 | kfree(client->dev.platform_data); | |
301 | i2c_unregister_device(client); | |
302 | } | |
303 | EXPORT_SYMBOL_GPL(i2c_free_slave_host_notify_device); | |
304 | #endif | |
305 | ||
5ace6085 JD |
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_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 | ||
3d50b95b CL |
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 | */ | |
5ace6085 | 367 | switch (common_mem_type) { |
3d50b95b | 368 | case 0x12: /* DDR */ |
5ace6085 JD |
369 | case 0x13: /* DDR2 */ |
370 | case 0x18: /* DDR3 */ | |
3d50b95b | 371 | case 0x1B: /* LPDDR */ |
5ace6085 JD |
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)); | |
0b0221d9 | 398 | strscpy(info.type, name, I2C_NAME_SIZE); |
5ace6085 JD |
399 | addr_list[0] = 0x50 + n; |
400 | addr_list[1] = I2C_CLIENT_END; | |
401 | ||
402 | if (!IS_ERR(i2c_new_scanned_device(adap, &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 | ||
7c81c60f | 413 | MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>"); |
b5527a77 JD |
414 | MODULE_DESCRIPTION("SMBus protocol extensions support"); |
415 | MODULE_LICENSE("GPL"); |