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 #include <linux/thermal.h>
28
29 #define MAX_PWM 255
30
31 struct pwm_fan_ctx {
32 struct mutex lock;
33 struct pwm_device *pwm;
34 unsigned int pwm_value;
35 unsigned int pwm_fan_state;
36 unsigned int pwm_fan_max_state;
37 unsigned int *pwm_fan_cooling_levels;
38 struct thermal_cooling_device *cdev;
39 };
40
__set_pwm(struct pwm_fan_ctx * ctx,unsigned long pwm)41 static int __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
42 {
43 unsigned long duty;
44 int ret = 0;
45
46 mutex_lock(&ctx->lock);
47 if (ctx->pwm_value == pwm)
48 goto exit_set_pwm_err;
49
50 duty = DIV_ROUND_UP(pwm * (ctx->pwm->period - 1), MAX_PWM);
51 ret = pwm_config(ctx->pwm, duty, ctx->pwm->period);
52 if (ret)
53 goto exit_set_pwm_err;
54
55 if (pwm == 0)
56 pwm_disable(ctx->pwm);
57
58 if (ctx->pwm_value == 0) {
59 ret = pwm_enable(ctx->pwm);
60 if (ret)
61 goto exit_set_pwm_err;
62 }
63
64 ctx->pwm_value = pwm;
65 exit_set_pwm_err:
66 mutex_unlock(&ctx->lock);
67 return ret;
68 }
69
pwm_fan_update_state(struct pwm_fan_ctx * ctx,unsigned long pwm)70 static void pwm_fan_update_state(struct pwm_fan_ctx *ctx, unsigned long pwm)
71 {
72 int i;
73
74 for (i = 0; i < ctx->pwm_fan_max_state; ++i)
75 if (pwm < ctx->pwm_fan_cooling_levels[i + 1])
76 break;
77
78 ctx->pwm_fan_state = i;
79 }
80
set_pwm(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)81 static ssize_t set_pwm(struct device *dev, struct device_attribute *attr,
82 const char *buf, size_t count)
83 {
84 struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
85 unsigned long pwm;
86 int ret;
87
88 if (kstrtoul(buf, 10, &pwm) || pwm > MAX_PWM)
89 return -EINVAL;
90
91 ret = __set_pwm(ctx, pwm);
92 if (ret)
93 return ret;
94
95 pwm_fan_update_state(ctx, pwm);
96 return count;
97 }
98
show_pwm(struct device * dev,struct device_attribute * attr,char * buf)99 static ssize_t show_pwm(struct device *dev,
100 struct device_attribute *attr, char *buf)
101 {
102 struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
103
104 return sprintf(buf, "%u\n", ctx->pwm_value);
105 }
106
107
108 static SENSOR_DEVICE_ATTR(pwm1, S_IRUGO | S_IWUSR, show_pwm, set_pwm, 0);
109
110 static struct attribute *pwm_fan_attrs[] = {
111 &sensor_dev_attr_pwm1.dev_attr.attr,
112 NULL,
113 };
114
115 ATTRIBUTE_GROUPS(pwm_fan);
116
117 /* thermal cooling device callbacks */
pwm_fan_get_max_state(struct thermal_cooling_device * cdev,unsigned long * state)118 static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
119 unsigned long *state)
120 {
121 struct pwm_fan_ctx *ctx = cdev->devdata;
122
123 if (!ctx)
124 return -EINVAL;
125
126 *state = ctx->pwm_fan_max_state;
127
128 return 0;
129 }
130
pwm_fan_get_cur_state(struct thermal_cooling_device * cdev,unsigned long * state)131 static int pwm_fan_get_cur_state(struct thermal_cooling_device *cdev,
132 unsigned long *state)
133 {
134 struct pwm_fan_ctx *ctx = cdev->devdata;
135
136 if (!ctx)
137 return -EINVAL;
138
139 *state = ctx->pwm_fan_state;
140
141 return 0;
142 }
143
144 static int
pwm_fan_set_cur_state(struct thermal_cooling_device * cdev,unsigned long state)145 pwm_fan_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
146 {
147 struct pwm_fan_ctx *ctx = cdev->devdata;
148 int ret;
149
150 if (!ctx || (state > ctx->pwm_fan_max_state))
151 return -EINVAL;
152
153 if (state == ctx->pwm_fan_state)
154 return 0;
155
156 ret = __set_pwm(ctx, ctx->pwm_fan_cooling_levels[state]);
157 if (ret) {
158 dev_err(&cdev->device, "Cannot set pwm!\n");
159 return ret;
160 }
161
162 ctx->pwm_fan_state = state;
163
164 return ret;
165 }
166
167 static const struct thermal_cooling_device_ops pwm_fan_cooling_ops = {
168 .get_max_state = pwm_fan_get_max_state,
169 .get_cur_state = pwm_fan_get_cur_state,
170 .set_cur_state = pwm_fan_set_cur_state,
171 };
172
pwm_fan_of_get_cooling_data(struct device * dev,struct pwm_fan_ctx * ctx)173 static int pwm_fan_of_get_cooling_data(struct device *dev,
174 struct pwm_fan_ctx *ctx)
175 {
176 struct device_node *np = dev->of_node;
177 int num, i, ret;
178
179 if (!of_find_property(np, "cooling-levels", NULL))
180 return 0;
181
182 ret = of_property_count_u32_elems(np, "cooling-levels");
183 if (ret <= 0) {
184 dev_err(dev, "Wrong data!\n");
185 return ret ? : -EINVAL;
186 }
187
188 num = ret;
189 ctx->pwm_fan_cooling_levels = devm_kzalloc(dev, num * sizeof(u32),
190 GFP_KERNEL);
191 if (!ctx->pwm_fan_cooling_levels)
192 return -ENOMEM;
193
194 ret = of_property_read_u32_array(np, "cooling-levels",
195 ctx->pwm_fan_cooling_levels, num);
196 if (ret) {
197 dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
198 return ret;
199 }
200
201 for (i = 0; i < num; i++) {
202 if (ctx->pwm_fan_cooling_levels[i] > MAX_PWM) {
203 dev_err(dev, "PWM fan state[%d]:%d > %d\n", i,
204 ctx->pwm_fan_cooling_levels[i], MAX_PWM);
205 return -EINVAL;
206 }
207 }
208
209 ctx->pwm_fan_max_state = num - 1;
210
211 return 0;
212 }
213
pwm_fan_probe(struct platform_device * pdev)214 static int pwm_fan_probe(struct platform_device *pdev)
215 {
216 struct thermal_cooling_device *cdev;
217 struct pwm_fan_ctx *ctx;
218 struct device *hwmon;
219 int duty_cycle;
220 int ret;
221
222 ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
223 if (!ctx)
224 return -ENOMEM;
225
226 mutex_init(&ctx->lock);
227
228 ctx->pwm = devm_of_pwm_get(&pdev->dev, pdev->dev.of_node, NULL);
229 if (IS_ERR(ctx->pwm)) {
230 ret = PTR_ERR(ctx->pwm);
231
232 if (ret != -EPROBE_DEFER)
233 dev_err(&pdev->dev, "Could not get PWM: %d\n", ret);
234
235 return ret;
236 }
237
238 platform_set_drvdata(pdev, ctx);
239
240 /* Set duty cycle to maximum allowed */
241 duty_cycle = ctx->pwm->period - 1;
242 ctx->pwm_value = MAX_PWM;
243
244 ret = pwm_config(ctx->pwm, duty_cycle, ctx->pwm->period);
245 if (ret) {
246 dev_err(&pdev->dev, "Failed to configure PWM\n");
247 return ret;
248 }
249
250 /* Enbale PWM output */
251 ret = pwm_enable(ctx->pwm);
252 if (ret) {
253 dev_err(&pdev->dev, "Failed to enable PWM\n");
254 return ret;
255 }
256
257 hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan",
258 ctx, pwm_fan_groups);
259 if (IS_ERR(hwmon)) {
260 dev_err(&pdev->dev, "Failed to register hwmon device\n");
261 pwm_disable(ctx->pwm);
262 return PTR_ERR(hwmon);
263 }
264
265 ret = pwm_fan_of_get_cooling_data(&pdev->dev, ctx);
266 if (ret)
267 return ret;
268
269 ctx->pwm_fan_state = ctx->pwm_fan_max_state;
270 if (IS_ENABLED(CONFIG_THERMAL)) {
271 cdev = thermal_of_cooling_device_register(pdev->dev.of_node,
272 "pwm-fan", ctx,
273 &pwm_fan_cooling_ops);
274 if (IS_ERR(cdev)) {
275 dev_err(&pdev->dev,
276 "Failed to register pwm-fan as cooling device");
277 pwm_disable(ctx->pwm);
278 return PTR_ERR(cdev);
279 }
280 ctx->cdev = cdev;
281 thermal_cdev_update(cdev);
282 }
283
284 return 0;
285 }
286
pwm_fan_remove(struct platform_device * pdev)287 static int pwm_fan_remove(struct platform_device *pdev)
288 {
289 struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev);
290
291 thermal_cooling_device_unregister(ctx->cdev);
292 if (ctx->pwm_value)
293 pwm_disable(ctx->pwm);
294 return 0;
295 }
296
297 #ifdef CONFIG_PM_SLEEP
pwm_fan_suspend(struct device * dev)298 static int pwm_fan_suspend(struct device *dev)
299 {
300 struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
301
302 if (ctx->pwm_value)
303 pwm_disable(ctx->pwm);
304 return 0;
305 }
306
pwm_fan_resume(struct device * dev)307 static int pwm_fan_resume(struct device *dev)
308 {
309 struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
310 unsigned long duty;
311 int ret;
312
313 if (ctx->pwm_value == 0)
314 return 0;
315
316 duty = DIV_ROUND_UP(ctx->pwm_value * (ctx->pwm->period - 1), MAX_PWM);
317 ret = pwm_config(ctx->pwm, duty, ctx->pwm->period);
318 if (ret)
319 return ret;
320 return pwm_enable(ctx->pwm);
321 }
322 #endif
323
324 static SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume);
325
326 static const struct of_device_id of_pwm_fan_match[] = {
327 { .compatible = "pwm-fan", },
328 {},
329 };
330 MODULE_DEVICE_TABLE(of, of_pwm_fan_match);
331
332 static struct platform_driver pwm_fan_driver = {
333 .probe = pwm_fan_probe,
334 .remove = pwm_fan_remove,
335 .driver = {
336 .name = "pwm-fan",
337 .pm = &pwm_fan_pm,
338 .of_match_table = of_pwm_fan_match,
339 },
340 };
341
342 module_platform_driver(pwm_fan_driver);
343
344 MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>");
345 MODULE_ALIAS("platform:pwm-fan");
346 MODULE_DESCRIPTION("PWM FAN driver");
347 MODULE_LICENSE("GPL");
348