--- /dev/null
+/*
+ * pwm-fan.c - Hwmon driver for fans connected to PWM lines.
+ *
+ * Copyright (c) 2014 Samsung Electronics Co., Ltd.
+ *
+ * Author: Kamil Debski <k.debski@samsung.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/sysfs.h>
+
+#define MAX_PWM 255
+
+struct pwm_fan_ctx {
+ struct mutex lock;
+ struct pwm_device *pwm;
+ unsigned char pwm_value;
+};
+
+static ssize_t set_pwm(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
+ unsigned long pwm, duty;
+ ssize_t ret;
+
+ if (kstrtoul(buf, 10, &pwm) || pwm > MAX_PWM)
+ return -EINVAL;
+
+ mutex_lock(&ctx->lock);
+
+ if (ctx->pwm_value == pwm)
+ goto exit_set_pwm_no_change;
+
+ if (pwm == 0) {
+ pwm_disable(ctx->pwm);
+ goto exit_set_pwm;
+ }
+
+ duty = DIV_ROUND_UP(pwm * (ctx->pwm->period - 1), MAX_PWM);
+ ret = pwm_config(ctx->pwm, duty, ctx->pwm->period);
+ if (ret)
+ goto exit_set_pwm_err;
+
+ if (ctx->pwm_value == 0) {
+ ret = pwm_enable(ctx->pwm);
+ if (ret)
+ goto exit_set_pwm_err;
+ }
+
+exit_set_pwm:
+ ctx->pwm_value = pwm;
+exit_set_pwm_no_change:
+ ret = count;
+exit_set_pwm_err:
+ mutex_unlock(&ctx->lock);
+ return ret;
+}
+
+static ssize_t show_pwm(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
+
+ return sprintf(buf, "%u\n", ctx->pwm_value);
+}
+
+
+static SENSOR_DEVICE_ATTR(pwm1, S_IRUGO | S_IWUSR, show_pwm, set_pwm, 0);
+
+static struct attribute *pwm_fan_attrs[] = {
+ &sensor_dev_attr_pwm1.dev_attr.attr,
+ NULL,
+};
+
+ATTRIBUTE_GROUPS(pwm_fan);
+
+static int pwm_fan_probe(struct platform_device *pdev)
+{
+ struct device *hwmon;
+ struct pwm_fan_ctx *ctx;
+ int duty_cycle;
+ int ret;
+
+ ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
+ if (!ctx)
+ return -ENOMEM;
+
+ mutex_init(&ctx->lock);
+
+ ctx->pwm = devm_of_pwm_get(&pdev->dev, pdev->dev.of_node, NULL);
+ if (IS_ERR(ctx->pwm)) {
+ dev_err(&pdev->dev, "Could not get PWM\n");
+ return PTR_ERR(ctx->pwm);
+ }
+
+ dev_set_drvdata(&pdev->dev, ctx);
+ platform_set_drvdata(pdev, ctx);
+
+ /* Set duty cycle to maximum allowed */
+ duty_cycle = ctx->pwm->period - 1;
+ ctx->pwm_value = MAX_PWM;
+
+ ret = pwm_config(ctx->pwm, duty_cycle, ctx->pwm->period);
+ if (ret) {
+ dev_err(&pdev->dev, "Failed to configure PWM\n");
+ return ret;
+ }
+
+ /* Enbale PWM output */
+ ret = pwm_enable(ctx->pwm);
+ if (ret) {
+ dev_err(&pdev->dev, "Failed to enable PWM\n");
+ return ret;
+ }
+
+ hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan",
+ ctx, pwm_fan_groups);
+ if (IS_ERR(hwmon)) {
+ dev_err(&pdev->dev, "Failed to register hwmon device\n");
+ pwm_disable(ctx->pwm);
+ return PTR_ERR(hwmon);
+ }
+ return 0;
+}
+
+static int pwm_fan_remove(struct platform_device *pdev)
+{
+ struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev);
+
+ if (ctx->pwm_value)
+ pwm_disable(ctx->pwm);
+ return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int pwm_fan_suspend(struct device *dev)
+{
+ struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
+
+ if (ctx->pwm_value)
+ pwm_disable(ctx->pwm);
+ return 0;
+}
+
+static int pwm_fan_resume(struct device *dev)
+{
+ struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
+
+ if (ctx->pwm_value)
+ return pwm_enable(ctx->pwm);
+ return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume);
+
+static struct of_device_id of_pwm_fan_match[] = {
+ { .compatible = "pwm-fan", },
+ {},
+};
+
+static struct platform_driver pwm_fan_driver = {
+ .probe = pwm_fan_probe,
+ .remove = pwm_fan_remove,
+ .driver = {
+ .name = "pwm-fan",
+ .pm = &pwm_fan_pm,
+ .of_match_table = of_pwm_fan_match,
+ },
+};
+
+module_platform_driver(pwm_fan_driver);
+
+MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>");
+MODULE_ALIAS("platform:pwm-fan");
+MODULE_DESCRIPTION("PWM FAN driver");
+MODULE_LICENSE("GPL");
git.samba.org / sfrench / cifs-2.6.git / commitdiff