diff options
Diffstat (limited to 'drivers/hwmon/pwm-fan.c')
| -rw-r--r-- | drivers/hwmon/pwm-fan.c | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c new file mode 100644 index 00000000000..d5421c023b4 --- /dev/null +++ b/drivers/hwmon/pwm-fan.c @@ -0,0 +1,201 @@ +/* + * 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_attributes[] = { + &sensor_dev_attr_pwm1.dev_attr.attr, + NULL, +}; + +static const struct attribute_group pwm_fan_group = { + .attrs = pwm_fan_attributes, +}; + +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, 0); + 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; + } + + /* Enable PWM output */ + ret = pwm_enable(ctx->pwm); + if (ret) { + dev_err(&pdev->dev, "Failed to enable PWM\n"); + return ret; + } + + ret = sysfs_create_group(&pdev->dev.kobj, &pwm_fan_group); + if (ret) + return ret; + + hwmon = hwmon_device_register(&pdev->dev); + + if (IS_ERR(hwmon)) { + dev_err(&pdev->dev, "Failed to register hwmon device"); + 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); + mutex_destroy(&ctx->lock); + 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"); |