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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
20struct i2c_smbus_alert {
21 struct work_struct alert;
22 struct i2c_client *ara; /* Alert response address */
23};
24
25struct 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 */
32static 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 */
66static 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(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(&ara->adapter->dev, &data,
98 smbus_do_alert);
99 }
100
101 return IRQ_HANDLED;
102}
103
104static 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(0, alert);
111
112}
113
114/* Setup SMBALERT# infrastructure */
115static int smbalert_probe(struct i2c_client *ara)
116{
117 struct i2c_smbus_alert_setup *setup = dev_get_platdata(&ara->dev);
118 struct i2c_smbus_alert *alert;
119 struct i2c_adapter *adapter = ara->adapter;
120 int res, irq;
121
122 alert = devm_kzalloc(&ara->dev, 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 "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(&ara->dev, irq,
141 NULL, smbus_alert,
142 IRQF_SHARED | IRQF_ONESHOT,
143 "smbus_alert", alert);
144 if (res)
145 return res;
146 }
147
148 i2c_set_clientdata(ara, 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 */
155static void smbalert_remove(struct i2c_client *ara)
156{
157 struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
158
159 cancel_work_sync(&alert->alert);
160}
161
162static const struct i2c_device_id smbalert_ids[] = {
163 { "smbus_alert", 0 },
164 { /* LIST END */ }
165};
166MODULE_DEVICE_TABLE(i2c, smbalert_ids);
167
168static struct i2c_driver smbalert_driver = {
169 .driver = {
170 .name = "smbus_alert",
171 },
172 .probe_new = 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 */
189int 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}
195EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert);
196
197module_i2c_driver(smbalert_driver);
198
199#if IS_ENABLED(CONFIG_I2C_SLAVE)
200#define SMBUS_HOST_NOTIFY_LEN 3
201struct i2c_slave_host_notify_status {
202 u8 index;
203 u8 addr;
204};
205
206static 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 */
252struct 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}
284EXPORT_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 */
294void 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}
303EXPORT_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)
315void 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
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(info.type, name, I2C_NAME_SIZE);
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}
410EXPORT_SYMBOL_GPL(i2c_register_spd);
411#endif
412
413MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
414MODULE_DESCRIPTION("SMBus protocol extensions support");
415MODULE_LICENSE("GPL");
1/*
2 * i2c-smbus.c - SMBus extensions to the I2C protocol
3 *
4 * Copyright (C) 2008 David Brownell
5 * Copyright (C) 2010 Jean Delvare <jdelvare@suse.de>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 */
17
18#include <linux/device.h>
19#include <linux/i2c.h>
20#include <linux/i2c-smbus.h>
21#include <linux/interrupt.h>
22#include <linux/kernel.h>
23#include <linux/module.h>
24#include <linux/slab.h>
25#include <linux/workqueue.h>
26
27struct i2c_smbus_alert {
28 unsigned int alert_edge_triggered:1;
29 int irq;
30 struct work_struct alert;
31 struct i2c_client *ara; /* Alert response address */
32};
33
34struct alert_data {
35 unsigned short addr;
36 enum i2c_alert_protocol type;
37 unsigned int data;
38};
39
40/* If this is the alerting device, notify its driver */
41static int smbus_do_alert(struct device *dev, void *addrp)
42{
43 struct i2c_client *client = i2c_verify_client(dev);
44 struct alert_data *data = addrp;
45 struct i2c_driver *driver;
46
47 if (!client || client->addr != data->addr)
48 return 0;
49 if (client->flags & I2C_CLIENT_TEN)
50 return 0;
51
52 /*
53 * Drivers should either disable alerts, or provide at least
54 * a minimal handler. Lock so the driver won't change.
55 */
56 device_lock(dev);
57 if (client->dev.driver) {
58 driver = to_i2c_driver(client->dev.driver);
59 if (driver->alert)
60 driver->alert(client, data->type, data->data);
61 else
62 dev_warn(&client->dev, "no driver alert()!\n");
63 } else
64 dev_dbg(&client->dev, "alert with no driver\n");
65 device_unlock(dev);
66
67 /* Stop iterating after we find the device */
68 return -EBUSY;
69}
70
71/*
72 * The alert IRQ handler needs to hand work off to a task which can issue
73 * SMBus calls, because those sleeping calls can't be made in IRQ context.
74 */
75static void smbus_alert(struct work_struct *work)
76{
77 struct i2c_smbus_alert *alert;
78 struct i2c_client *ara;
79 unsigned short prev_addr = 0; /* Not a valid address */
80
81 alert = container_of(work, struct i2c_smbus_alert, alert);
82 ara = alert->ara;
83
84 for (;;) {
85 s32 status;
86 struct alert_data data;
87
88 /*
89 * Devices with pending alerts reply in address order, low
90 * to high, because of slave transmit arbitration. After
91 * responding, an SMBus device stops asserting SMBALERT#.
92 *
93 * Note that SMBus 2.0 reserves 10-bit addresses for future
94 * use. We neither handle them, nor try to use PEC here.
95 */
96 status = i2c_smbus_read_byte(ara);
97 if (status < 0)
98 break;
99
100 data.data = status & 1;
101 data.addr = status >> 1;
102 data.type = I2C_PROTOCOL_SMBUS_ALERT;
103
104 if (data.addr == prev_addr) {
105 dev_warn(&ara->dev, "Duplicate SMBALERT# from dev "
106 "0x%02x, skipping\n", data.addr);
107 break;
108 }
109 dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n",
110 data.addr, data.data);
111
112 /* Notify driver for the device which issued the alert */
113 device_for_each_child(&ara->adapter->dev, &data,
114 smbus_do_alert);
115 prev_addr = data.addr;
116 }
117
118 /* We handled all alerts; re-enable level-triggered IRQs */
119 if (!alert->alert_edge_triggered)
120 enable_irq(alert->irq);
121}
122
123static irqreturn_t smbalert_irq(int irq, void *d)
124{
125 struct i2c_smbus_alert *alert = d;
126
127 /* Disable level-triggered IRQs until we handle them */
128 if (!alert->alert_edge_triggered)
129 disable_irq_nosync(irq);
130
131 schedule_work(&alert->alert);
132 return IRQ_HANDLED;
133}
134
135/* Setup SMBALERT# infrastructure */
136static int smbalert_probe(struct i2c_client *ara,
137 const struct i2c_device_id *id)
138{
139 struct i2c_smbus_alert_setup *setup = dev_get_platdata(&ara->dev);
140 struct i2c_smbus_alert *alert;
141 struct i2c_adapter *adapter = ara->adapter;
142 int res;
143
144 alert = devm_kzalloc(&ara->dev, sizeof(struct i2c_smbus_alert),
145 GFP_KERNEL);
146 if (!alert)
147 return -ENOMEM;
148
149 alert->alert_edge_triggered = setup->alert_edge_triggered;
150 alert->irq = setup->irq;
151 INIT_WORK(&alert->alert, smbus_alert);
152 alert->ara = ara;
153
154 if (setup->irq > 0) {
155 res = devm_request_irq(&ara->dev, setup->irq, smbalert_irq,
156 0, "smbus_alert", alert);
157 if (res)
158 return res;
159 }
160
161 i2c_set_clientdata(ara, alert);
162 dev_info(&adapter->dev, "supports SMBALERT#, %s trigger\n",
163 setup->alert_edge_triggered ? "edge" : "level");
164
165 return 0;
166}
167
168/* IRQ and memory resources are managed so they are freed automatically */
169static int smbalert_remove(struct i2c_client *ara)
170{
171 struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
172
173 cancel_work_sync(&alert->alert);
174 return 0;
175}
176
177static const struct i2c_device_id smbalert_ids[] = {
178 { "smbus_alert", 0 },
179 { /* LIST END */ }
180};
181MODULE_DEVICE_TABLE(i2c, smbalert_ids);
182
183static struct i2c_driver smbalert_driver = {
184 .driver = {
185 .name = "smbus_alert",
186 },
187 .probe = smbalert_probe,
188 .remove = smbalert_remove,
189 .id_table = smbalert_ids,
190};
191
192/**
193 * i2c_setup_smbus_alert - Setup SMBus alert support
194 * @adapter: the target adapter
195 * @setup: setup data for the SMBus alert handler
196 * Context: can sleep
197 *
198 * Setup handling of the SMBus alert protocol on a given I2C bus segment.
199 *
200 * Handling can be done either through our IRQ handler, or by the
201 * adapter (from its handler, periodic polling, or whatever).
202 *
203 * NOTE that if we manage the IRQ, we *MUST* know if it's level or
204 * edge triggered in order to hand it to the workqueue correctly.
205 * If triggering the alert seems to wedge the system, you probably
206 * should have said it's level triggered.
207 *
208 * This returns the ara client, which should be saved for later use with
209 * i2c_handle_smbus_alert() and ultimately i2c_unregister_device(); or NULL
210 * to indicate an error.
211 */
212struct i2c_client *i2c_setup_smbus_alert(struct i2c_adapter *adapter,
213 struct i2c_smbus_alert_setup *setup)
214{
215 struct i2c_board_info ara_board_info = {
216 I2C_BOARD_INFO("smbus_alert", 0x0c),
217 .platform_data = setup,
218 };
219
220 return i2c_new_device(adapter, &ara_board_info);
221}
222EXPORT_SYMBOL_GPL(i2c_setup_smbus_alert);
223
224/**
225 * i2c_handle_smbus_alert - Handle an SMBus alert
226 * @ara: the ARA client on the relevant adapter
227 * Context: can't sleep
228 *
229 * Helper function to be called from an I2C bus driver's interrupt
230 * handler. It will schedule the alert work, in turn calling the
231 * corresponding I2C device driver's alert function.
232 *
233 * It is assumed that ara is a valid i2c client previously returned by
234 * i2c_setup_smbus_alert().
235 */
236int i2c_handle_smbus_alert(struct i2c_client *ara)
237{
238 struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
239
240 return schedule_work(&alert->alert);
241}
242EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert);
243
244module_i2c_driver(smbalert_driver);
245
246MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
247MODULE_DESCRIPTION("SMBus protocol extensions support");
248MODULE_LICENSE("GPL");