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