1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
|
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* i2c-smbus.c - SMBus extensions to the I2C protocol
*
* Copyright (C) 2008 David Brownell
* Copyright (C) 2010 Jean Delvare <jdelvare@suse.de>
*/
#include <linux/device.h>
#include <linux/i2c.h>
#include <linux/i2c-smbus.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_irq.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
struct i2c_smbus_alert {
struct work_struct alert;
struct i2c_client *ara; /* Alert response address */
};
struct alert_data {
unsigned short addr;
enum i2c_alert_protocol type;
unsigned int data;
};
/* If this is the alerting device, notify its driver */
static int smbus_do_alert(struct device *dev, void *addrp)
{
struct i2c_client *client = i2c_verify_client(dev);
struct alert_data *data = addrp;
struct i2c_driver *driver;
if (!client || client->addr != data->addr)
return 0;
if (client->flags & I2C_CLIENT_TEN)
return 0;
/*
* Drivers should either disable alerts, or provide at least
* a minimal handler. Lock so the driver won't change.
*/
device_lock(dev);
if (client->dev.driver) {
driver = to_i2c_driver(client->dev.driver);
if (driver->alert)
driver->alert(client, data->type, data->data);
else
dev_warn(&client->dev, "no driver alert()!\n");
} else
dev_dbg(&client->dev, "alert with no driver\n");
device_unlock(dev);
/* Stop iterating after we find the device */
return -EBUSY;
}
/*
* The alert IRQ handler needs to hand work off to a task which can issue
* SMBus calls, because those sleeping calls can't be made in IRQ context.
*/
static irqreturn_t smbus_alert(int irq, void *d)
{
struct i2c_smbus_alert *alert = d;
struct i2c_client *ara;
ara = alert->ara;
for (;;) {
s32 status;
struct alert_data data;
/*
* Devices with pending alerts reply in address order, low
* to high, because of slave transmit arbitration. After
* responding, an SMBus device stops asserting SMBALERT#.
*
* Note that SMBus 2.0 reserves 10-bit addresses for future
* use. We neither handle them, nor try to use PEC here.
*/
status = i2c_smbus_read_byte(ara);
if (status < 0)
break;
data.data = status & 1;
data.addr = status >> 1;
data.type = I2C_PROTOCOL_SMBUS_ALERT;
dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n",
data.addr, data.data);
/* Notify driver for the device which issued the alert */
device_for_each_child(&ara->adapter->dev, &data,
smbus_do_alert);
}
return IRQ_HANDLED;
}
static void smbalert_work(struct work_struct *work)
{
struct i2c_smbus_alert *alert;
alert = container_of(work, struct i2c_smbus_alert, alert);
smbus_alert(0, alert);
}
/* Setup SMBALERT# infrastructure */
static int smbalert_probe(struct i2c_client *ara,
const struct i2c_device_id *id)
{
struct i2c_smbus_alert_setup *setup = dev_get_platdata(&ara->dev);
struct i2c_smbus_alert *alert;
struct i2c_adapter *adapter = ara->adapter;
int res, irq;
alert = devm_kzalloc(&ara->dev, sizeof(struct i2c_smbus_alert),
GFP_KERNEL);
if (!alert)
return -ENOMEM;
if (setup) {
irq = setup->irq;
} else {
irq = of_irq_get_byname(adapter->dev.of_node, "smbus_alert");
if (irq <= 0)
return irq;
}
INIT_WORK(&alert->alert, smbalert_work);
alert->ara = ara;
if (irq > 0) {
res = devm_request_threaded_irq(&ara->dev, irq,
NULL, smbus_alert,
IRQF_SHARED | IRQF_ONESHOT,
"smbus_alert", alert);
if (res)
return res;
}
i2c_set_clientdata(ara, alert);
dev_info(&adapter->dev, "supports SMBALERT#\n");
return 0;
}
/* IRQ and memory resources are managed so they are freed automatically */
static int smbalert_remove(struct i2c_client *ara)
{
struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
cancel_work_sync(&alert->alert);
return 0;
}
static const struct i2c_device_id smbalert_ids[] = {
{ "smbus_alert", 0 },
{ /* LIST END */ }
};
MODULE_DEVICE_TABLE(i2c, smbalert_ids);
static struct i2c_driver smbalert_driver = {
.driver = {
.name = "smbus_alert",
},
.probe = smbalert_probe,
.remove = smbalert_remove,
.id_table = smbalert_ids,
};
/**
* i2c_handle_smbus_alert - Handle an SMBus alert
* @ara: the ARA client on the relevant adapter
* Context: can't sleep
*
* Helper function to be called from an I2C bus driver's interrupt
* handler. It will schedule the alert work, in turn calling the
* corresponding I2C device driver's alert function.
*
* It is assumed that ara is a valid i2c client previously returned by
* i2c_new_smbus_alert_device().
*/
int i2c_handle_smbus_alert(struct i2c_client *ara)
{
struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
return schedule_work(&alert->alert);
}
EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert);
module_i2c_driver(smbalert_driver);
MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
MODULE_DESCRIPTION("SMBus protocol extensions support");
MODULE_LICENSE("GPL");
|
