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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 <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., 51 Franklin Street, Fifth Floor, Boston,
20 * MA 02110-1301 USA.
21 */
22
23#include <linux/kernel.h>
24#include <linux/module.h>
25#include <linux/device.h>
26#include <linux/interrupt.h>
27#include <linux/workqueue.h>
28#include <linux/i2c.h>
29#include <linux/i2c-smbus.h>
30#include <linux/slab.h>
31
32struct i2c_smbus_alert {
33 unsigned int alert_edge_triggered:1;
34 int irq;
35 struct work_struct alert;
36 struct i2c_client *ara; /* Alert response address */
37};
38
39struct alert_data {
40 unsigned short addr;
41 u8 flag:1;
42};
43
44/* If this is the alerting device, notify its driver */
45static int smbus_do_alert(struct device *dev, void *addrp)
46{
47 struct i2c_client *client = i2c_verify_client(dev);
48 struct alert_data *data = addrp;
49
50 if (!client || client->addr != data->addr)
51 return 0;
52 if (client->flags & I2C_CLIENT_TEN)
53 return 0;
54
55 /*
56 * Drivers should either disable alerts, or provide at least
57 * a minimal handler. Lock so client->driver won't change.
58 */
59 device_lock(dev);
60 if (client->driver) {
61 if (client->driver->alert)
62 client->driver->alert(client, data->flag);
63 else
64 dev_warn(&client->dev, "no driver alert()!\n");
65 } else
66 dev_dbg(&client->dev, "alert with no driver\n");
67 device_unlock(dev);
68
69 /* Stop iterating after we find the device */
70 return -EBUSY;
71}
72
73/*
74 * The alert IRQ handler needs to hand work off to a task which can issue
75 * SMBus calls, because those sleeping calls can't be made in IRQ context.
76 */
77static void smbus_alert(struct work_struct *work)
78{
79 struct i2c_smbus_alert *alert;
80 struct i2c_client *ara;
81 unsigned short prev_addr = 0; /* Not a valid address */
82
83 alert = container_of(work, struct i2c_smbus_alert, alert);
84 ara = alert->ara;
85
86 for (;;) {
87 s32 status;
88 struct alert_data data;
89
90 /*
91 * Devices with pending alerts reply in address order, low
92 * to high, because of slave transmit arbitration. After
93 * responding, an SMBus device stops asserting SMBALERT#.
94 *
95 * Note that SMBus 2.0 reserves 10-bit addresess for future
96 * use. We neither handle them, nor try to use PEC here.
97 */
98 status = i2c_smbus_read_byte(ara);
99 if (status < 0)
100 break;
101
102 data.flag = status & 1;
103 data.addr = status >> 1;
104
105 if (data.addr == prev_addr) {
106 dev_warn(&ara->dev, "Duplicate SMBALERT# from dev "
107 "0x%02x, skipping\n", data.addr);
108 break;
109 }
110 dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n",
111 data.addr, data.flag);
112
113 /* Notify driver for the device which issued the alert */
114 device_for_each_child(&ara->adapter->dev, &data,
115 smbus_do_alert);
116 prev_addr = data.addr;
117 }
118
119 /* We handled all alerts; re-enable level-triggered IRQs */
120 if (!alert->alert_edge_triggered)
121 enable_irq(alert->irq);
122}
123
124static irqreturn_t smbalert_irq(int irq, void *d)
125{
126 struct i2c_smbus_alert *alert = d;
127
128 /* Disable level-triggered IRQs until we handle them */
129 if (!alert->alert_edge_triggered)
130 disable_irq_nosync(irq);
131
132 schedule_work(&alert->alert);
133 return IRQ_HANDLED;
134}
135
136/* Setup SMBALERT# infrastructure */
137static int smbalert_probe(struct i2c_client *ara,
138 const struct i2c_device_id *id)
139{
140 struct i2c_smbus_alert_setup *setup = ara->dev.platform_data;
141 struct i2c_smbus_alert *alert;
142 struct i2c_adapter *adapter = ara->adapter;
143 int res;
144
145 alert = kzalloc(sizeof(struct i2c_smbus_alert), 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 kfree(alert);
159 return res;
160 }
161 }
162
163 i2c_set_clientdata(ara, alert);
164 dev_info(&adapter->dev, "supports SMBALERT#, %s trigger\n",
165 setup->alert_edge_triggered ? "edge" : "level");
166
167 return 0;
168}
169
170/* IRQ resource is managed so it is freed automatically */
171static int smbalert_remove(struct i2c_client *ara)
172{
173 struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
174
175 cancel_work_sync(&alert->alert);
176
177 kfree(alert);
178 return 0;
179}
180
181static const struct i2c_device_id smbalert_ids[] = {
182 { "smbus_alert", 0 },
183 { /* LIST END */ }
184};
185MODULE_DEVICE_TABLE(i2c, smbalert_ids);
186
187static struct i2c_driver smbalert_driver = {
188 .driver = {
189 .name = "smbus_alert",
190 },
191 .probe = smbalert_probe,
192 .remove = smbalert_remove,
193 .id_table = smbalert_ids,
194};
195
196/**
197 * i2c_setup_smbus_alert - Setup SMBus alert support
198 * @adapter: the target adapter
199 * @setup: setup data for the SMBus alert handler
200 * Context: can sleep
201 *
202 * Setup handling of the SMBus alert protocol on a given I2C bus segment.
203 *
204 * Handling can be done either through our IRQ handler, or by the
205 * adapter (from its handler, periodic polling, or whatever).
206 *
207 * NOTE that if we manage the IRQ, we *MUST* know if it's level or
208 * edge triggered in order to hand it to the workqueue correctly.
209 * If triggering the alert seems to wedge the system, you probably
210 * should have said it's level triggered.
211 *
212 * This returns the ara client, which should be saved for later use with
213 * i2c_handle_smbus_alert() and ultimately i2c_unregister_device(); or NULL
214 * to indicate an error.
215 */
216struct i2c_client *i2c_setup_smbus_alert(struct i2c_adapter *adapter,
217 struct i2c_smbus_alert_setup *setup)
218{
219 struct i2c_board_info ara_board_info = {
220 I2C_BOARD_INFO("smbus_alert", 0x0c),
221 .platform_data = setup,
222 };
223
224 return i2c_new_device(adapter, &ara_board_info);
225}
226EXPORT_SYMBOL_GPL(i2c_setup_smbus_alert);
227
228/**
229 * i2c_handle_smbus_alert - Handle an SMBus alert
230 * @ara: the ARA client on the relevant adapter
231 * Context: can't sleep
232 *
233 * Helper function to be called from an I2C bus driver's interrupt
234 * handler. It will schedule the alert work, in turn calling the
235 * corresponding I2C device driver's alert function.
236 *
237 * It is assumed that ara is a valid i2c client previously returned by
238 * i2c_setup_smbus_alert().
239 */
240int i2c_handle_smbus_alert(struct i2c_client *ara)
241{
242 struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
243
244 return schedule_work(&alert->alert);
245}
246EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert);
247
248static int __init i2c_smbus_init(void)
249{
250 return i2c_add_driver(&smbalert_driver);
251}
252
253static void __exit i2c_smbus_exit(void)
254{
255 i2c_del_driver(&smbalert_driver);
256}
257
258module_init(i2c_smbus_init);
259module_exit(i2c_smbus_exit);
260
261MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
262MODULE_DESCRIPTION("SMBus protocol extensions support");
263MODULE_LICENSE("GPL");