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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
31struct 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
41static int __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
42{
43 struct pwm_args pargs;
44 unsigned long duty;
45 int ret = 0;
46
47 pwm_get_args(ctx->pwm, &pargs);
48
49 mutex_lock(&ctx->lock);
50 if (ctx->pwm_value == pwm)
51 goto exit_set_pwm_err;
52
53 duty = DIV_ROUND_UP(pwm * (pargs.period - 1), MAX_PWM);
54 ret = pwm_config(ctx->pwm, duty, pargs.period);
55 if (ret)
56 goto exit_set_pwm_err;
57
58 if (pwm == 0)
59 pwm_disable(ctx->pwm);
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 ctx->pwm_value = pwm;
68exit_set_pwm_err:
69 mutex_unlock(&ctx->lock);
70 return ret;
71}
72
73static void pwm_fan_update_state(struct pwm_fan_ctx *ctx, unsigned long pwm)
74{
75 int i;
76
77 for (i = 0; i < ctx->pwm_fan_max_state; ++i)
78 if (pwm < ctx->pwm_fan_cooling_levels[i + 1])
79 break;
80
81 ctx->pwm_fan_state = i;
82}
83
84static ssize_t set_pwm(struct device *dev, struct device_attribute *attr,
85 const char *buf, size_t count)
86{
87 struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
88 unsigned long pwm;
89 int ret;
90
91 if (kstrtoul(buf, 10, &pwm) || pwm > MAX_PWM)
92 return -EINVAL;
93
94 ret = __set_pwm(ctx, pwm);
95 if (ret)
96 return ret;
97
98 pwm_fan_update_state(ctx, pwm);
99 return count;
100}
101
102static ssize_t show_pwm(struct device *dev,
103 struct device_attribute *attr, char *buf)
104{
105 struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
106
107 return sprintf(buf, "%u\n", ctx->pwm_value);
108}
109
110
111static SENSOR_DEVICE_ATTR(pwm1, S_IRUGO | S_IWUSR, show_pwm, set_pwm, 0);
112
113static struct attribute *pwm_fan_attrs[] = {
114 &sensor_dev_attr_pwm1.dev_attr.attr,
115 NULL,
116};
117
118ATTRIBUTE_GROUPS(pwm_fan);
119
120/* thermal cooling device callbacks */
121static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
122 unsigned long *state)
123{
124 struct pwm_fan_ctx *ctx = cdev->devdata;
125
126 if (!ctx)
127 return -EINVAL;
128
129 *state = ctx->pwm_fan_max_state;
130
131 return 0;
132}
133
134static int pwm_fan_get_cur_state(struct thermal_cooling_device *cdev,
135 unsigned long *state)
136{
137 struct pwm_fan_ctx *ctx = cdev->devdata;
138
139 if (!ctx)
140 return -EINVAL;
141
142 *state = ctx->pwm_fan_state;
143
144 return 0;
145}
146
147static int
148pwm_fan_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
149{
150 struct pwm_fan_ctx *ctx = cdev->devdata;
151 int ret;
152
153 if (!ctx || (state > ctx->pwm_fan_max_state))
154 return -EINVAL;
155
156 if (state == ctx->pwm_fan_state)
157 return 0;
158
159 ret = __set_pwm(ctx, ctx->pwm_fan_cooling_levels[state]);
160 if (ret) {
161 dev_err(&cdev->device, "Cannot set pwm!\n");
162 return ret;
163 }
164
165 ctx->pwm_fan_state = state;
166
167 return ret;
168}
169
170static const struct thermal_cooling_device_ops pwm_fan_cooling_ops = {
171 .get_max_state = pwm_fan_get_max_state,
172 .get_cur_state = pwm_fan_get_cur_state,
173 .set_cur_state = pwm_fan_set_cur_state,
174};
175
176static int pwm_fan_of_get_cooling_data(struct device *dev,
177 struct pwm_fan_ctx *ctx)
178{
179 struct device_node *np = dev->of_node;
180 int num, i, ret;
181
182 if (!of_find_property(np, "cooling-levels", NULL))
183 return 0;
184
185 ret = of_property_count_u32_elems(np, "cooling-levels");
186 if (ret <= 0) {
187 dev_err(dev, "Wrong data!\n");
188 return ret ? : -EINVAL;
189 }
190
191 num = ret;
192 ctx->pwm_fan_cooling_levels = devm_kzalloc(dev, num * sizeof(u32),
193 GFP_KERNEL);
194 if (!ctx->pwm_fan_cooling_levels)
195 return -ENOMEM;
196
197 ret = of_property_read_u32_array(np, "cooling-levels",
198 ctx->pwm_fan_cooling_levels, num);
199 if (ret) {
200 dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
201 return ret;
202 }
203
204 for (i = 0; i < num; i++) {
205 if (ctx->pwm_fan_cooling_levels[i] > MAX_PWM) {
206 dev_err(dev, "PWM fan state[%d]:%d > %d\n", i,
207 ctx->pwm_fan_cooling_levels[i], MAX_PWM);
208 return -EINVAL;
209 }
210 }
211
212 ctx->pwm_fan_max_state = num - 1;
213
214 return 0;
215}
216
217static int pwm_fan_probe(struct platform_device *pdev)
218{
219 struct thermal_cooling_device *cdev;
220 struct pwm_fan_ctx *ctx;
221 struct pwm_args pargs;
222 struct device *hwmon;
223 int duty_cycle;
224 int ret;
225
226 ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
227 if (!ctx)
228 return -ENOMEM;
229
230 mutex_init(&ctx->lock);
231
232 ctx->pwm = devm_of_pwm_get(&pdev->dev, pdev->dev.of_node, NULL);
233 if (IS_ERR(ctx->pwm)) {
234 dev_err(&pdev->dev, "Could not get PWM\n");
235 return PTR_ERR(ctx->pwm);
236 }
237
238 platform_set_drvdata(pdev, ctx);
239
240 /*
241 * FIXME: pwm_apply_args() should be removed when switching to the
242 * atomic PWM API.
243 */
244 pwm_apply_args(ctx->pwm);
245
246 /* Set duty cycle to maximum allowed */
247 pwm_get_args(ctx->pwm, &pargs);
248
249 duty_cycle = pargs.period - 1;
250 ctx->pwm_value = MAX_PWM;
251
252 ret = pwm_config(ctx->pwm, duty_cycle, pargs.period);
253 if (ret) {
254 dev_err(&pdev->dev, "Failed to configure PWM\n");
255 return ret;
256 }
257
258 /* Enbale PWM output */
259 ret = pwm_enable(ctx->pwm);
260 if (ret) {
261 dev_err(&pdev->dev, "Failed to enable PWM\n");
262 return ret;
263 }
264
265 hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan",
266 ctx, pwm_fan_groups);
267 if (IS_ERR(hwmon)) {
268 dev_err(&pdev->dev, "Failed to register hwmon device\n");
269 pwm_disable(ctx->pwm);
270 return PTR_ERR(hwmon);
271 }
272
273 ret = pwm_fan_of_get_cooling_data(&pdev->dev, ctx);
274 if (ret)
275 return ret;
276
277 ctx->pwm_fan_state = ctx->pwm_fan_max_state;
278 if (IS_ENABLED(CONFIG_THERMAL)) {
279 cdev = thermal_of_cooling_device_register(pdev->dev.of_node,
280 "pwm-fan", ctx,
281 &pwm_fan_cooling_ops);
282 if (IS_ERR(cdev)) {
283 dev_err(&pdev->dev,
284 "Failed to register pwm-fan as cooling device");
285 pwm_disable(ctx->pwm);
286 return PTR_ERR(cdev);
287 }
288 ctx->cdev = cdev;
289 thermal_cdev_update(cdev);
290 }
291
292 return 0;
293}
294
295static int pwm_fan_remove(struct platform_device *pdev)
296{
297 struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev);
298
299 thermal_cooling_device_unregister(ctx->cdev);
300 if (ctx->pwm_value)
301 pwm_disable(ctx->pwm);
302 return 0;
303}
304
305#ifdef CONFIG_PM_SLEEP
306static int pwm_fan_suspend(struct device *dev)
307{
308 struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
309
310 if (ctx->pwm_value)
311 pwm_disable(ctx->pwm);
312 return 0;
313}
314
315static int pwm_fan_resume(struct device *dev)
316{
317 struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
318 struct pwm_args pargs;
319 unsigned long duty;
320 int ret;
321
322 if (ctx->pwm_value == 0)
323 return 0;
324
325 pwm_get_args(ctx->pwm, &pargs);
326 duty = DIV_ROUND_UP(ctx->pwm_value * (pargs.period - 1), MAX_PWM);
327 ret = pwm_config(ctx->pwm, duty, pargs.period);
328 if (ret)
329 return ret;
330 return pwm_enable(ctx->pwm);
331}
332#endif
333
334static SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume);
335
336static const struct of_device_id of_pwm_fan_match[] = {
337 { .compatible = "pwm-fan", },
338 {},
339};
340MODULE_DEVICE_TABLE(of, of_pwm_fan_match);
341
342static struct platform_driver pwm_fan_driver = {
343 .probe = pwm_fan_probe,
344 .remove = pwm_fan_remove,
345 .driver = {
346 .name = "pwm-fan",
347 .pm = &pwm_fan_pm,
348 .of_match_table = of_pwm_fan_match,
349 },
350};
351
352module_platform_driver(pwm_fan_driver);
353
354MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>");
355MODULE_ALIAS("platform:pwm-fan");
356MODULE_DESCRIPTION("PWM FAN driver");
357MODULE_LICENSE("GPL");