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d82d5776 KD |
1 | /* |
2 | * pwm-fan.c - Hwmon driver for fans connected to PWM lines. | |
3 | * | |
4 | * Copyright (c) 2014 Samsung Electronics Co., Ltd. | |
5 | * | |
6 | * Author: Kamil Debski <k.debski@samsung.com> | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License as published by | |
10 | * the Free Software Foundation; either version 2 of the License, or | |
11 | * (at your option) any later version. | |
12 | * | |
13 | * This program is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | * GNU General Public License for more details. | |
17 | */ | |
18 | ||
19 | #include <linux/hwmon.h> | |
20 | #include <linux/hwmon-sysfs.h> | |
21 | #include <linux/module.h> | |
22 | #include <linux/mutex.h> | |
23 | #include <linux/of.h> | |
24 | #include <linux/platform_device.h> | |
25 | #include <linux/pwm.h> | |
26 | #include <linux/sysfs.h> | |
27 | ||
28 | #define MAX_PWM 255 | |
29 | ||
30 | struct pwm_fan_ctx { | |
31 | struct mutex lock; | |
32 | struct pwm_device *pwm; | |
33 | unsigned char pwm_value; | |
34 | }; | |
35 | ||
36 | static ssize_t set_pwm(struct device *dev, struct device_attribute *attr, | |
37 | const char *buf, size_t count) | |
38 | { | |
39 | struct pwm_fan_ctx *ctx = dev_get_drvdata(dev); | |
40 | unsigned long pwm, duty; | |
41 | ssize_t ret; | |
42 | ||
43 | if (kstrtoul(buf, 10, &pwm) || pwm > MAX_PWM) | |
44 | return -EINVAL; | |
45 | ||
46 | mutex_lock(&ctx->lock); | |
47 | ||
48 | if (ctx->pwm_value == pwm) | |
49 | goto exit_set_pwm_no_change; | |
50 | ||
51 | if (pwm == 0) { | |
52 | pwm_disable(ctx->pwm); | |
53 | goto exit_set_pwm; | |
54 | } | |
55 | ||
56 | duty = DIV_ROUND_UP(pwm * (ctx->pwm->period - 1), MAX_PWM); | |
57 | ret = pwm_config(ctx->pwm, duty, ctx->pwm->period); | |
58 | if (ret) | |
59 | goto exit_set_pwm_err; | |
60 | ||
61 | if (ctx->pwm_value == 0) { | |
62 | ret = pwm_enable(ctx->pwm); | |
63 | if (ret) | |
64 | goto exit_set_pwm_err; | |
65 | } | |
66 | ||
67 | exit_set_pwm: | |
68 | ctx->pwm_value = pwm; | |
69 | exit_set_pwm_no_change: | |
70 | ret = count; | |
71 | exit_set_pwm_err: | |
72 | mutex_unlock(&ctx->lock); | |
73 | return ret; | |
74 | } | |
75 | ||
76 | static ssize_t show_pwm(struct device *dev, | |
77 | struct device_attribute *attr, char *buf) | |
78 | { | |
79 | struct pwm_fan_ctx *ctx = dev_get_drvdata(dev); | |
80 | ||
81 | return sprintf(buf, "%u\n", ctx->pwm_value); | |
82 | } | |
83 | ||
84 | ||
85 | static SENSOR_DEVICE_ATTR(pwm1, S_IRUGO | S_IWUSR, show_pwm, set_pwm, 0); | |
86 | ||
87 | static struct attribute *pwm_fan_attrs[] = { | |
88 | &sensor_dev_attr_pwm1.dev_attr.attr, | |
89 | NULL, | |
90 | }; | |
91 | ||
92 | ATTRIBUTE_GROUPS(pwm_fan); | |
93 | ||
94 | static int pwm_fan_probe(struct platform_device *pdev) | |
95 | { | |
96 | struct device *hwmon; | |
97 | struct pwm_fan_ctx *ctx; | |
98 | int duty_cycle; | |
99 | int ret; | |
100 | ||
101 | ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL); | |
102 | if (!ctx) | |
103 | return -ENOMEM; | |
104 | ||
105 | mutex_init(&ctx->lock); | |
106 | ||
107 | ctx->pwm = devm_of_pwm_get(&pdev->dev, pdev->dev.of_node, NULL); | |
108 | if (IS_ERR(ctx->pwm)) { | |
109 | dev_err(&pdev->dev, "Could not get PWM\n"); | |
110 | return PTR_ERR(ctx->pwm); | |
111 | } | |
112 | ||
d82d5776 KD |
113 | platform_set_drvdata(pdev, ctx); |
114 | ||
115 | /* Set duty cycle to maximum allowed */ | |
116 | duty_cycle = ctx->pwm->period - 1; | |
117 | ctx->pwm_value = MAX_PWM; | |
118 | ||
119 | ret = pwm_config(ctx->pwm, duty_cycle, ctx->pwm->period); | |
120 | if (ret) { | |
121 | dev_err(&pdev->dev, "Failed to configure PWM\n"); | |
122 | return ret; | |
123 | } | |
124 | ||
125 | /* Enbale PWM output */ | |
126 | ret = pwm_enable(ctx->pwm); | |
127 | if (ret) { | |
128 | dev_err(&pdev->dev, "Failed to enable PWM\n"); | |
129 | return ret; | |
130 | } | |
131 | ||
132 | hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan", | |
133 | ctx, pwm_fan_groups); | |
134 | if (IS_ERR(hwmon)) { | |
135 | dev_err(&pdev->dev, "Failed to register hwmon device\n"); | |
136 | pwm_disable(ctx->pwm); | |
137 | return PTR_ERR(hwmon); | |
138 | } | |
139 | return 0; | |
140 | } | |
141 | ||
142 | static int pwm_fan_remove(struct platform_device *pdev) | |
143 | { | |
144 | struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev); | |
145 | ||
146 | if (ctx->pwm_value) | |
147 | pwm_disable(ctx->pwm); | |
148 | return 0; | |
149 | } | |
150 | ||
151 | #ifdef CONFIG_PM_SLEEP | |
152 | static int pwm_fan_suspend(struct device *dev) | |
153 | { | |
154 | struct pwm_fan_ctx *ctx = dev_get_drvdata(dev); | |
155 | ||
156 | if (ctx->pwm_value) | |
157 | pwm_disable(ctx->pwm); | |
158 | return 0; | |
159 | } | |
160 | ||
161 | static int pwm_fan_resume(struct device *dev) | |
162 | { | |
163 | struct pwm_fan_ctx *ctx = dev_get_drvdata(dev); | |
48b9d5b4 KD |
164 | unsigned long duty; |
165 | int ret; | |
d82d5776 | 166 | |
48b9d5b4 KD |
167 | if (ctx->pwm_value == 0) |
168 | return 0; | |
169 | ||
170 | duty = DIV_ROUND_UP(ctx->pwm_value * (ctx->pwm->period - 1), MAX_PWM); | |
171 | ret = pwm_config(ctx->pwm, duty, ctx->pwm->period); | |
172 | if (ret) | |
173 | return ret; | |
174 | return pwm_enable(ctx->pwm); | |
d82d5776 KD |
175 | } |
176 | #endif | |
177 | ||
178 | static SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume); | |
179 | ||
180 | static struct of_device_id of_pwm_fan_match[] = { | |
181 | { .compatible = "pwm-fan", }, | |
182 | {}, | |
183 | }; | |
184 | ||
185 | static struct platform_driver pwm_fan_driver = { | |
186 | .probe = pwm_fan_probe, | |
187 | .remove = pwm_fan_remove, | |
188 | .driver = { | |
189 | .name = "pwm-fan", | |
190 | .pm = &pwm_fan_pm, | |
191 | .of_match_table = of_pwm_fan_match, | |
192 | }, | |
193 | }; | |
194 | ||
195 | module_platform_driver(pwm_fan_driver); | |
196 | ||
197 | MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>"); | |
198 | MODULE_ALIAS("platform:pwm-fan"); | |
199 | MODULE_DESCRIPTION("PWM FAN driver"); | |
200 | MODULE_LICENSE("GPL"); |