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
|
/*
* pwm-fan.c - Hwmon driver for fans connected to PWM lines.
*
* Copyright (c) 2014 Samsung Electronics Co., Ltd.
*
* Author: Kamil Debski <k.debski@samsung.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/sysfs.h>
#define MAX_PWM 255
struct pwm_fan_ctx {
struct mutex lock;
struct pwm_device *pwm;
unsigned char pwm_value;
};
static ssize_t set_pwm(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
unsigned long pwm, duty;
ssize_t ret;
if (kstrtoul(buf, 10, &pwm) || pwm > MAX_PWM)
return -EINVAL;
mutex_lock(&ctx->lock);
if (ctx->pwm_value == pwm)
goto exit_set_pwm_no_change;
if (pwm == 0) {
pwm_disable(ctx->pwm);
goto exit_set_pwm;
}
duty = DIV_ROUND_UP(pwm * (ctx->pwm->period - 1), MAX_PWM);
ret = pwm_config(ctx->pwm, duty, ctx->pwm->period);
if (ret)
goto exit_set_pwm_err;
if (ctx->pwm_value == 0) {
ret = pwm_enable(ctx->pwm);
if (ret)
goto exit_set_pwm_err;
}
exit_set_pwm:
ctx->pwm_value = pwm;
exit_set_pwm_no_change:
ret = count;
exit_set_pwm_err:
mutex_unlock(&ctx->lock);
return ret;
}
static ssize_t show_pwm(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
return sprintf(buf, "%u\n", ctx->pwm_value);
}
static SENSOR_DEVICE_ATTR(pwm1, S_IRUGO | S_IWUSR, show_pwm, set_pwm, 0);
static struct attribute *pwm_fan_attributes[] = {
&sensor_dev_attr_pwm1.dev_attr.attr,
NULL,
};
static const struct attribute_group pwm_fan_group = {
.attrs = pwm_fan_attributes,
};
static int pwm_fan_probe(struct platform_device *pdev)
{
struct device *hwmon;
struct pwm_fan_ctx *ctx;
int duty_cycle;
int ret;
ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
if (!ctx)
return -ENOMEM;
mutex_init(&ctx->lock);
ctx->pwm = devm_of_pwm_get(&pdev->dev, pdev->dev.of_node, 0);
if (IS_ERR(ctx->pwm)) {
dev_err(&pdev->dev, "Could not get PWM\n");
return PTR_ERR(ctx->pwm);
}
dev_set_drvdata(&pdev->dev, ctx);
platform_set_drvdata(pdev, ctx);
/* Set duty cycle to maximum allowed */
duty_cycle = ctx->pwm->period - 1;
ctx->pwm_value = MAX_PWM;
ret = pwm_config(ctx->pwm, duty_cycle, ctx->pwm->period);
if (ret) {
dev_err(&pdev->dev, "Failed to configure PWM\n");
return ret;
}
/* Enable PWM output */
ret = pwm_enable(ctx->pwm);
if (ret) {
dev_err(&pdev->dev, "Failed to enable PWM\n");
return ret;
}
ret = sysfs_create_group(&pdev->dev.kobj, &pwm_fan_group);
if (ret)
return ret;
hwmon = hwmon_device_register(&pdev->dev);
if (IS_ERR(hwmon)) {
dev_err(&pdev->dev, "Failed to register hwmon device");
pwm_disable(ctx->pwm);
return PTR_ERR(hwmon);
}
return 0;
}
static int pwm_fan_remove(struct platform_device *pdev)
{
struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev);
if (ctx->pwm_value)
pwm_disable(ctx->pwm);
mutex_destroy(&ctx->lock);
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int pwm_fan_suspend(struct device *dev)
{
struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
if (ctx->pwm_value)
pwm_disable(ctx->pwm);
return 0;
}
static int pwm_fan_resume(struct device *dev)
{
struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
if (ctx->pwm_value)
return pwm_enable(ctx->pwm);
return 0;
}
#endif
static SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume);
static struct of_device_id of_pwm_fan_match[] = {
{ .compatible = "pwm-fan", },
{},
};
static struct platform_driver pwm_fan_driver = {
.probe = pwm_fan_probe,
.remove = pwm_fan_remove,
.driver = {
.name = "pwm-fan",
.pm = &pwm_fan_pm,
.of_match_table = of_pwm_fan_match,
},
};
module_platform_driver(pwm_fan_driver);
MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>");
MODULE_ALIAS("platform:pwm-fan");
MODULE_DESCRIPTION("PWM FAN driver");
MODULE_LICENSE("GPL");
|
