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1/*
2 * i2c-smbus.c - SMBus extensions to the I2C protocol
3 *
4 * Copyright (C) 2008 David Brownell
5 * Copyright (C) 2010 Jean Delvare <khali@linux-fr.org>
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 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 */
21
22#include <linux/kernel.h>
23#include <linux/module.h>
24#include <linux/device.h>
25#include <linux/interrupt.h>
26#include <linux/workqueue.h>
27#include <linux/i2c.h>
28#include <linux/i2c-smbus.h>
29#include <linux/slab.h>
30
31struct i2c_smbus_alert {
32 unsigned int alert_edge_triggered:1;
33 int irq;
34 struct work_struct alert;
35 struct i2c_client *ara; /* Alert response address */
36};
37
38struct alert_data {
39 unsigned short addr;
40 u8 flag:1;
41};
42
43/* If this is the alerting device, notify its driver */
44static int smbus_do_alert(struct device *dev, void *addrp)
45{
46 struct i2c_client *client = i2c_verify_client(dev);
47 struct alert_data *data = addrp;
48
49 if (!client || client->addr != data->addr)
50 return 0;
51 if (client->flags & I2C_CLIENT_TEN)
52 return 0;
53
54 /*
55 * Drivers should either disable alerts, or provide at least
56 * a minimal handler. Lock so client->driver won't change.
57 */
58 device_lock(dev);
59 if (client->driver) {
60 if (client->driver->alert)
61 client->driver->alert(client, data->flag);
62 else
63 dev_warn(&client->dev, "no driver alert()!\n");
64 } else
65 dev_dbg(&client->dev, "alert with no driver\n");
66 device_unlock(dev);
67
68 /* Stop iterating after we find the device */
69 return -EBUSY;
70}
71
72/*
73 * The alert IRQ handler needs to hand work off to a task which can issue
74 * SMBus calls, because those sleeping calls can't be made in IRQ context.
75 */
76static void smbus_alert(struct work_struct *work)
77{
78 struct i2c_smbus_alert *alert;
79 struct i2c_client *ara;
80 unsigned short prev_addr = 0; /* Not a valid address */
81
82 alert = container_of(work, struct i2c_smbus_alert, alert);
83 ara = alert->ara;
84
85 for (;;) {
86 s32 status;
87 struct alert_data data;
88
89 /*
90 * Devices with pending alerts reply in address order, low
91 * to high, because of slave transmit arbitration. After
92 * responding, an SMBus device stops asserting SMBALERT#.
93 *
94 * Note that SMBus 2.0 reserves 10-bit addresess for future
95 * use. We neither handle them, nor try to use PEC here.
96 */
97 status = i2c_smbus_read_byte(ara);
98 if (status < 0)
99 break;
100
101 data.flag = status & 1;
102 data.addr = status >> 1;
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.flag);
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 = ara->dev.platform_data;
140 struct i2c_smbus_alert *alert;
141 struct i2c_adapter *adapter = ara->adapter;
142 int res;
143
144 alert = kzalloc(sizeof(struct i2c_smbus_alert), GFP_KERNEL);
145 if (!alert)
146 return -ENOMEM;
147
148 alert->alert_edge_triggered = setup->alert_edge_triggered;
149 alert->irq = setup->irq;
150 INIT_WORK(&alert->alert, smbus_alert);
151 alert->ara = ara;
152
153 if (setup->irq > 0) {
154 res = devm_request_irq(&ara->dev, setup->irq, smbalert_irq,
155 0, "smbus_alert", alert);
156 if (res) {
157 kfree(alert);
158 return res;
159 }
160 }
161
162 i2c_set_clientdata(ara, alert);
163 dev_info(&adapter->dev, "supports SMBALERT#, %s trigger\n",
164 setup->alert_edge_triggered ? "edge" : "level");
165
166 return 0;
167}
168
169/* IRQ resource is managed so it is freed automatically */
170static int smbalert_remove(struct i2c_client *ara)
171{
172 struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
173
174 cancel_work_sync(&alert->alert);
175
176 kfree(alert);
177 return 0;
178}
179
180static const struct i2c_device_id smbalert_ids[] = {
181 { "smbus_alert", 0 },
182 { /* LIST END */ }
183};
184MODULE_DEVICE_TABLE(i2c, smbalert_ids);
185
186static struct i2c_driver smbalert_driver = {
187 .driver = {
188 .name = "smbus_alert",
189 },
190 .probe = smbalert_probe,
191 .remove = smbalert_remove,
192 .id_table = smbalert_ids,
193};
194
195/**
196 * i2c_setup_smbus_alert - Setup SMBus alert support
197 * @adapter: the target adapter
198 * @setup: setup data for the SMBus alert handler
199 * Context: can sleep
200 *
201 * Setup handling of the SMBus alert protocol on a given I2C bus segment.
202 *
203 * Handling can be done either through our IRQ handler, or by the
204 * adapter (from its handler, periodic polling, or whatever).
205 *
206 * NOTE that if we manage the IRQ, we *MUST* know if it's level or
207 * edge triggered in order to hand it to the workqueue correctly.
208 * If triggering the alert seems to wedge the system, you probably
209 * should have said it's level triggered.
210 *
211 * This returns the ara client, which should be saved for later use with
212 * i2c_handle_smbus_alert() and ultimately i2c_unregister_device(); or NULL
213 * to indicate an error.
214 */
215struct i2c_client *i2c_setup_smbus_alert(struct i2c_adapter *adapter,
216 struct i2c_smbus_alert_setup *setup)
217{
218 struct i2c_board_info ara_board_info = {
219 I2C_BOARD_INFO("smbus_alert", 0x0c),
220 .platform_data = setup,
221 };
222
223 return i2c_new_device(adapter, &ara_board_info);
224}
225EXPORT_SYMBOL_GPL(i2c_setup_smbus_alert);
226
227/**
228 * i2c_handle_smbus_alert - Handle an SMBus alert
229 * @ara: the ARA client on the relevant adapter
230 * Context: can't sleep
231 *
232 * Helper function to be called from an I2C bus driver's interrupt
233 * handler. It will schedule the alert work, in turn calling the
234 * corresponding I2C device driver's alert function.
235 *
236 * It is assumed that ara is a valid i2c client previously returned by
237 * i2c_setup_smbus_alert().
238 */
239int i2c_handle_smbus_alert(struct i2c_client *ara)
240{
241 struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
242
243 return schedule_work(&alert->alert);
244}
245EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert);
246
247static int __init i2c_smbus_init(void)
248{
249 return i2c_add_driver(&smbalert_driver);
250}
251
252static void __exit i2c_smbus_exit(void)
253{
254 i2c_del_driver(&smbalert_driver);
255}
256
257module_init(i2c_smbus_init);
258module_exit(i2c_smbus_exit);
259
260MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
261MODULE_DESCRIPTION("SMBus protocol extensions support");
262MODULE_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");