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b5527a77 JD |
1 | /* |
2 | * i2c-smbus.c - SMBus extensions to the I2C protocol | |
3 | * | |
4 | * Copyright (C) 2008 David Brownell | |
7c81c60f | 5 | * Copyright (C) 2010 Jean Delvare <jdelvare@suse.de> |
b5527a77 JD |
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. | |
b5527a77 JD |
16 | */ |
17 | ||
b5527a77 | 18 | #include <linux/device.h> |
b5527a77 JD |
19 | #include <linux/i2c.h> |
20 | #include <linux/i2c-smbus.h> | |
62c874ab WS |
21 | #include <linux/interrupt.h> |
22 | #include <linux/kernel.h> | |
23 | #include <linux/module.h> | |
5a0e3ad6 | 24 | #include <linux/slab.h> |
62c874ab | 25 | #include <linux/workqueue.h> |
b5527a77 JD |
26 | |
27 | struct 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 | ||
34 | struct alert_data { | |
35 | unsigned short addr; | |
e456cd37 BT |
36 | enum i2c_alert_protocol type; |
37 | unsigned int data; | |
b5527a77 JD |
38 | }; |
39 | ||
40 | /* If this is the alerting device, notify its driver */ | |
41 | static 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; | |
0acc2b32 | 45 | struct i2c_driver *driver; |
b5527a77 JD |
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 | |
0acc2b32 | 54 | * a minimal handler. Lock so the driver won't change. |
b5527a77 | 55 | */ |
f635a1e7 | 56 | device_lock(dev); |
0acc2b32 LPC |
57 | if (client->dev.driver) { |
58 | driver = to_i2c_driver(client->dev.driver); | |
59 | if (driver->alert) | |
e456cd37 | 60 | driver->alert(client, data->type, data->data); |
b5527a77 JD |
61 | else |
62 | dev_warn(&client->dev, "no driver alert()!\n"); | |
63 | } else | |
64 | dev_dbg(&client->dev, "alert with no driver\n"); | |
f635a1e7 | 65 | device_unlock(dev); |
b5527a77 JD |
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 | */ | |
75 | static 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 | * | |
edc9102a | 93 | * Note that SMBus 2.0 reserves 10-bit addresses for future |
b5527a77 JD |
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 | ||
e456cd37 | 100 | data.data = status & 1; |
b5527a77 | 101 | data.addr = status >> 1; |
e456cd37 | 102 | data.type = I2C_PROTOCOL_SMBUS_ALERT; |
b5527a77 JD |
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", | |
e456cd37 | 110 | data.addr, data.data); |
b5527a77 JD |
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 | ||
123 | static 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 */ | |
136 | static int smbalert_probe(struct i2c_client *ara, | |
137 | const struct i2c_device_id *id) | |
138 | { | |
6d4028c6 | 139 | struct i2c_smbus_alert_setup *setup = dev_get_platdata(&ara->dev); |
b5527a77 JD |
140 | struct i2c_smbus_alert *alert; |
141 | struct i2c_adapter *adapter = ara->adapter; | |
142 | int res; | |
143 | ||
71b57845 JL |
144 | alert = devm_kzalloc(&ara->dev, sizeof(struct i2c_smbus_alert), |
145 | GFP_KERNEL); | |
b5527a77 JD |
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); | |
71b57845 | 157 | if (res) |
b5527a77 | 158 | return res; |
b5527a77 JD |
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 | ||
71b57845 | 168 | /* IRQ and memory resources are managed so they are freed automatically */ |
b5527a77 JD |
169 | static 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); | |
b5527a77 JD |
174 | return 0; |
175 | } | |
176 | ||
177 | static const struct i2c_device_id smbalert_ids[] = { | |
178 | { "smbus_alert", 0 }, | |
179 | { /* LIST END */ } | |
180 | }; | |
181 | MODULE_DEVICE_TABLE(i2c, smbalert_ids); | |
182 | ||
183 | static 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 | */ | |
212 | struct 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 | } | |
222 | EXPORT_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 | */ | |
236 | int 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 | } | |
242 | EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert); | |
243 | ||
e456cd37 BT |
244 | static void smbus_host_notify_work(struct work_struct *work) |
245 | { | |
246 | struct alert_data alert; | |
247 | struct i2c_adapter *adapter; | |
248 | unsigned long flags; | |
249 | u16 payload; | |
250 | u8 addr; | |
251 | struct smbus_host_notify *data; | |
252 | ||
253 | data = container_of(work, struct smbus_host_notify, work); | |
254 | ||
255 | spin_lock_irqsave(&data->lock, flags); | |
256 | payload = data->payload; | |
257 | addr = data->addr; | |
258 | adapter = data->adapter; | |
259 | ||
260 | /* clear the pending bit and release the spinlock */ | |
261 | data->pending = false; | |
262 | spin_unlock_irqrestore(&data->lock, flags); | |
263 | ||
264 | if (!adapter || !addr) | |
265 | return; | |
266 | ||
267 | alert.type = I2C_PROTOCOL_SMBUS_HOST_NOTIFY; | |
268 | alert.addr = addr; | |
269 | alert.data = payload; | |
270 | ||
271 | device_for_each_child(&adapter->dev, &alert, smbus_do_alert); | |
272 | } | |
273 | ||
274 | /** | |
275 | * i2c_setup_smbus_host_notify - Allocate a new smbus_host_notify for the given | |
276 | * I2C adapter. | |
277 | * @adapter: the adapter we want to associate a Host Notify function | |
278 | * | |
279 | * Returns a struct smbus_host_notify pointer on success, and NULL on failure. | |
280 | * The resulting smbus_host_notify must not be freed afterwards, it is a | |
281 | * managed resource already. | |
282 | */ | |
283 | struct smbus_host_notify *i2c_setup_smbus_host_notify(struct i2c_adapter *adap) | |
284 | { | |
285 | struct smbus_host_notify *host_notify; | |
286 | ||
287 | host_notify = devm_kzalloc(&adap->dev, sizeof(struct smbus_host_notify), | |
288 | GFP_KERNEL); | |
289 | if (!host_notify) | |
290 | return NULL; | |
291 | ||
292 | host_notify->adapter = adap; | |
293 | ||
294 | spin_lock_init(&host_notify->lock); | |
295 | INIT_WORK(&host_notify->work, smbus_host_notify_work); | |
296 | ||
297 | return host_notify; | |
298 | } | |
299 | EXPORT_SYMBOL_GPL(i2c_setup_smbus_host_notify); | |
300 | ||
301 | /** | |
302 | * i2c_handle_smbus_host_notify - Forward a Host Notify event to the correct | |
303 | * I2C client. | |
304 | * @host_notify: the struct host_notify attached to the relevant adapter | |
1847bbd7 JD |
305 | * @addr: the I2C address of the notifying device |
306 | * @data: the payload of the notification | |
e456cd37 BT |
307 | * Context: can't sleep |
308 | * | |
309 | * Helper function to be called from an I2C bus driver's interrupt | |
310 | * handler. It will schedule the Host Notify work, in turn calling the | |
311 | * corresponding I2C device driver's alert function. | |
312 | * | |
313 | * host_notify should be a valid pointer previously returned by | |
314 | * i2c_setup_smbus_host_notify(). | |
315 | */ | |
316 | int i2c_handle_smbus_host_notify(struct smbus_host_notify *host_notify, | |
317 | unsigned short addr, unsigned int data) | |
318 | { | |
319 | unsigned long flags; | |
320 | struct i2c_adapter *adapter; | |
321 | ||
322 | if (!host_notify || !host_notify->adapter) | |
323 | return -EINVAL; | |
324 | ||
325 | adapter = host_notify->adapter; | |
326 | ||
327 | spin_lock_irqsave(&host_notify->lock, flags); | |
328 | ||
329 | if (host_notify->pending) { | |
330 | spin_unlock_irqrestore(&host_notify->lock, flags); | |
331 | dev_warn(&adapter->dev, "Host Notify already scheduled.\n"); | |
332 | return -EBUSY; | |
333 | } | |
334 | ||
335 | host_notify->payload = data; | |
336 | host_notify->addr = addr; | |
337 | ||
338 | /* Mark that there is a pending notification and release the lock */ | |
339 | host_notify->pending = true; | |
340 | spin_unlock_irqrestore(&host_notify->lock, flags); | |
341 | ||
342 | return schedule_work(&host_notify->work); | |
343 | } | |
344 | EXPORT_SYMBOL_GPL(i2c_handle_smbus_host_notify); | |
345 | ||
fda2f4af | 346 | module_i2c_driver(smbalert_driver); |
b5527a77 | 347 | |
7c81c60f | 348 | MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>"); |
b5527a77 JD |
349 | MODULE_DESCRIPTION("SMBus protocol extensions support"); |
350 | MODULE_LICENSE("GPL"); |