2 * i2c-smbus.c - SMBus extensions to the I2C protocol
4 * Copyright (C) 2008 David Brownell
5 * Copyright (C) 2010 Jean Delvare <jdelvare@suse.de>
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.
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.
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/of_irq.h>
25 #include <linux/slab.h>
26 #include <linux/workqueue.h>
28 struct i2c_smbus_alert {
29 struct work_struct alert;
30 struct i2c_client *ara; /* Alert response address */
35 enum i2c_alert_protocol type;
39 /* If this is the alerting device, notify its driver */
40 static int smbus_do_alert(struct device *dev, void *addrp)
42 struct i2c_client *client = i2c_verify_client(dev);
43 struct alert_data *data = addrp;
44 struct i2c_driver *driver;
46 if (!client || client->addr != data->addr)
48 if (client->flags & I2C_CLIENT_TEN)
52 * Drivers should either disable alerts, or provide at least
53 * a minimal handler. Lock so the driver won't change.
56 if (client->dev.driver) {
57 driver = to_i2c_driver(client->dev.driver);
59 driver->alert(client, data->type, data->data);
61 dev_warn(&client->dev, "no driver alert()!\n");
63 dev_dbg(&client->dev, "alert with no driver\n");
66 /* Stop iterating after we find the device */
71 * The alert IRQ handler needs to hand work off to a task which can issue
72 * SMBus calls, because those sleeping calls can't be made in IRQ context.
74 static irqreturn_t smbus_alert(int irq, void *d)
76 struct i2c_smbus_alert *alert = d;
77 struct i2c_client *ara;
78 unsigned short prev_addr = 0; /* Not a valid address */
84 struct alert_data data;
87 * Devices with pending alerts reply in address order, low
88 * to high, because of slave transmit arbitration. After
89 * responding, an SMBus device stops asserting SMBALERT#.
91 * Note that SMBus 2.0 reserves 10-bit addresses for future
92 * use. We neither handle them, nor try to use PEC here.
94 status = i2c_smbus_read_byte(ara);
98 data.data = status & 1;
99 data.addr = status >> 1;
100 data.type = I2C_PROTOCOL_SMBUS_ALERT;
102 if (data.addr == prev_addr) {
103 dev_warn(&ara->dev, "Duplicate SMBALERT# from dev "
104 "0x%02x, skipping\n", data.addr);
107 dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n",
108 data.addr, data.data);
110 /* Notify driver for the device which issued the alert */
111 device_for_each_child(&ara->adapter->dev, &data,
113 prev_addr = data.addr;
119 static void smbalert_work(struct work_struct *work)
121 struct i2c_smbus_alert *alert;
123 alert = container_of(work, struct i2c_smbus_alert, alert);
125 smbus_alert(0, alert);
129 /* Setup SMBALERT# infrastructure */
130 static int smbalert_probe(struct i2c_client *ara,
131 const struct i2c_device_id *id)
133 struct i2c_smbus_alert_setup *setup = dev_get_platdata(&ara->dev);
134 struct i2c_smbus_alert *alert;
135 struct i2c_adapter *adapter = ara->adapter;
138 alert = devm_kzalloc(&ara->dev, sizeof(struct i2c_smbus_alert),
146 irq = of_irq_get_byname(adapter->dev.of_node, "smbus_alert");
151 INIT_WORK(&alert->alert, smbalert_work);
155 res = devm_request_threaded_irq(&ara->dev, irq,
157 IRQF_SHARED | IRQF_ONESHOT,
158 "smbus_alert", alert);
163 i2c_set_clientdata(ara, alert);
164 dev_info(&adapter->dev, "supports SMBALERT#\n");
169 /* IRQ and memory resources are managed so they are freed automatically */
170 static int smbalert_remove(struct i2c_client *ara)
172 struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
174 cancel_work_sync(&alert->alert);
178 static const struct i2c_device_id smbalert_ids[] = {
179 { "smbus_alert", 0 },
182 MODULE_DEVICE_TABLE(i2c, smbalert_ids);
184 static struct i2c_driver smbalert_driver = {
186 .name = "smbus_alert",
188 .probe = smbalert_probe,
189 .remove = smbalert_remove,
190 .id_table = smbalert_ids,
194 * i2c_handle_smbus_alert - Handle an SMBus alert
195 * @ara: the ARA client on the relevant adapter
196 * Context: can't sleep
198 * Helper function to be called from an I2C bus driver's interrupt
199 * handler. It will schedule the alert work, in turn calling the
200 * corresponding I2C device driver's alert function.
202 * It is assumed that ara is a valid i2c client previously returned by
203 * i2c_setup_smbus_alert().
205 int i2c_handle_smbus_alert(struct i2c_client *ara)
207 struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
209 return schedule_work(&alert->alert);
211 EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert);
213 module_i2c_driver(smbalert_driver);
215 MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
216 MODULE_DESCRIPTION("SMBus protocol extensions support");
217 MODULE_LICENSE("GPL");