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	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;
65exit_set_pwm_err:
66	mutex_unlock(&ctx->lock);
67	return ret;
68}
69
70static 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
81static 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
99static 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
108static SENSOR_DEVICE_ATTR(pwm1, S_IRUGO | S_IWUSR, show_pwm, set_pwm, 0);
109
110static struct attribute *pwm_fan_attrs[] = {
111	&sensor_dev_attr_pwm1.dev_attr.attr,
112	NULL,
113};
114
115ATTRIBUTE_GROUPS(pwm_fan);
116
117/* thermal cooling device callbacks */
118static 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
131static 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
144static int
145pwm_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
167static 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
173static 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
214static 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		dev_err(&pdev->dev, "Could not get PWM\n");
231		return PTR_ERR(ctx->pwm);
232	}
233
234	platform_set_drvdata(pdev, ctx);
235
236	/* Set duty cycle to maximum allowed */
237	duty_cycle = ctx->pwm->period - 1;
238	ctx->pwm_value = MAX_PWM;
239
240	ret = pwm_config(ctx->pwm, duty_cycle, ctx->pwm->period);
241	if (ret) {
242		dev_err(&pdev->dev, "Failed to configure PWM\n");
243		return ret;
244	}
245
246	/* Enbale PWM output */
247	ret = pwm_enable(ctx->pwm);
248	if (ret) {
249		dev_err(&pdev->dev, "Failed to enable PWM\n");
250		return ret;
251	}
252
253	hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan",
254						       ctx, pwm_fan_groups);
255	if (IS_ERR(hwmon)) {
256		dev_err(&pdev->dev, "Failed to register hwmon device\n");
257		pwm_disable(ctx->pwm);
258		return PTR_ERR(hwmon);
259	}
260
261	ret = pwm_fan_of_get_cooling_data(&pdev->dev, ctx);
262	if (ret)
263		return ret;
264
265	ctx->pwm_fan_state = ctx->pwm_fan_max_state;
266	if (IS_ENABLED(CONFIG_THERMAL)) {
267		cdev = thermal_of_cooling_device_register(pdev->dev.of_node,
268							  "pwm-fan", ctx,
269							  &pwm_fan_cooling_ops);
270		if (IS_ERR(cdev)) {
271			dev_err(&pdev->dev,
272				"Failed to register pwm-fan as cooling device");
273			pwm_disable(ctx->pwm);
274			return PTR_ERR(cdev);
275		}
276		ctx->cdev = cdev;
277		thermal_cdev_update(cdev);
278	}
279
280	return 0;
281}
282
283static int pwm_fan_remove(struct platform_device *pdev)
284{
285	struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev);
286
287	thermal_cooling_device_unregister(ctx->cdev);
288	if (ctx->pwm_value)
289		pwm_disable(ctx->pwm);
290	return 0;
291}
292
293#ifdef CONFIG_PM_SLEEP
294static int pwm_fan_suspend(struct device *dev)
295{
296	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
297
298	if (ctx->pwm_value)
299		pwm_disable(ctx->pwm);
300	return 0;
301}
302
303static int pwm_fan_resume(struct device *dev)
304{
305	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
306	unsigned long duty;
307	int ret;
308
309	if (ctx->pwm_value == 0)
310		return 0;
311
312	duty = DIV_ROUND_UP(ctx->pwm_value * (ctx->pwm->period - 1), MAX_PWM);
313	ret = pwm_config(ctx->pwm, duty, ctx->pwm->period);
314	if (ret)
315		return ret;
316	return pwm_enable(ctx->pwm);
317}
318#endif
319
320static SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume);
321
322static const struct of_device_id of_pwm_fan_match[] = {
323	{ .compatible = "pwm-fan", },
324	{},
325};
326MODULE_DEVICE_TABLE(of, of_pwm_fan_match);
327
328static struct platform_driver pwm_fan_driver = {
329	.probe		= pwm_fan_probe,
330	.remove		= pwm_fan_remove,
331	.driver	= {
332		.name		= "pwm-fan",
333		.pm		= &pwm_fan_pm,
334		.of_match_table	= of_pwm_fan_match,
335	},
336};
337
338module_platform_driver(pwm_fan_driver);
339
340MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>");
341MODULE_ALIAS("platform:pwm-fan");
342MODULE_DESCRIPTION("PWM FAN driver");
343MODULE_LICENSE("GPL");
344