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