gpio-fan.c

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/*
 * gpio-fan.c - Hwmon driver for fans connected to GPIO lines.
 *
 * Copyright (C) 2010 LaCie
 *
 * Author: Simon Guinot <[email protected]>
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/platform_device.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/hwmon.h>
#include <linux/gpio.h>
#include <linux/gpio-fan.h>
#include <linux/of_platform.h>
#include <linux/of_gpio.h>

struct gpio_fan_data {
    struct platform_device  *pdev;
    struct device       *hwmon_dev;
    struct mutex        lock; /* lock GPIOs operations. */
    int         num_ctrl;
    unsigned        *ctrl;
    int         num_speed;
    struct gpio_fan_speed   *speed;
    int         speed_index;
#ifdef CONFIG_PM_SLEEP
    int         resume_speed;
#endif
    bool            pwm_enable;
    struct gpio_fan_alarm   *alarm;
    struct work_struct  alarm_work;
};

/*
 * Alarm GPIO.
 */

static void fan_alarm_notify(struct work_struct *ws)
{
    struct gpio_fan_data *fan_data =
        container_of(ws, struct gpio_fan_data, alarm_work);

    sysfs_notify(&fan_data->pdev->dev.kobj, NULL, "fan1_alarm");
    kobject_uevent(&fan_data->pdev->dev.kobj, KOBJ_CHANGE);
}

static irqreturn_t fan_alarm_irq_handler(int irq, void *dev_id)
{
    struct gpio_fan_data *fan_data = dev_id;

    schedule_work(&fan_data->alarm_work);

    return IRQ_NONE;
}

static ssize_t show_fan_alarm(struct device *dev,
                  struct device_attribute *attr, char *buf)
{
    struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
    struct gpio_fan_alarm *alarm = fan_data->alarm;
    int value = gpio_get_value(alarm->gpio);

    if (alarm->active_low)
        value = !value;

    return sprintf(buf, "%d\n", value);
}

static DEVICE_ATTR(fan1_alarm, S_IRUGO, show_fan_alarm, NULL);

static int fan_alarm_init(struct gpio_fan_data *fan_data,
              struct gpio_fan_alarm *alarm)
{
    int err;
    int alarm_irq;
    struct platform_device *pdev = fan_data->pdev;

    fan_data->alarm = alarm;

    err = devm_gpio_request(&pdev->dev, alarm->gpio, "GPIO fan alarm");
    if (err)
        return err;

    err = gpio_direction_input(alarm->gpio);
    if (err)
        return err;

    err = device_create_file(&pdev->dev, &dev_attr_fan1_alarm);
    if (err)
        return err;

    /*
     * If the alarm GPIO don't support interrupts, just leave
     * without initializing the fail notification support.
     */
    alarm_irq = gpio_to_irq(alarm->gpio);
    if (alarm_irq < 0)
        return 0;

    INIT_WORK(&fan_data->alarm_work, fan_alarm_notify);
    irq_set_irq_type(alarm_irq, IRQ_TYPE_EDGE_BOTH);
    err = devm_request_irq(&pdev->dev, alarm_irq, fan_alarm_irq_handler,
                   IRQF_SHARED, "GPIO fan alarm", fan_data);
    if (err)
        goto err_free_sysfs;

    return 0;

err_free_sysfs:
    device_remove_file(&pdev->dev, &dev_attr_fan1_alarm);
    return err;
}

static void fan_alarm_free(struct gpio_fan_data *fan_data)
{
    struct platform_device *pdev = fan_data->pdev;

    device_remove_file(&pdev->dev, &dev_attr_fan1_alarm);
}

/*
 * Control GPIOs.
 */

/* Must be called with fan_data->lock held, except during initialization. */
static void __set_fan_ctrl(struct gpio_fan_data *fan_data, int ctrl_val)
{
    int i;

    for (i = 0; i < fan_data->num_ctrl; i++)
        gpio_set_value(fan_data->ctrl[i], (ctrl_val >> i) & 1);
}

static int __get_fan_ctrl(struct gpio_fan_data *fan_data)
{
    int i;
    int ctrl_val = 0;

    for (i = 0; i < fan_data->num_ctrl; i++) {
        int value;

        value = gpio_get_value(fan_data->ctrl[i]);
        ctrl_val |= (value << i);
    }
    return ctrl_val;
}

/* Must be called with fan_data->lock held, except during initialization. */
static void set_fan_speed(struct gpio_fan_data *fan_data, int speed_index)
{
    if (fan_data->speed_index == speed_index)
        return;

    __set_fan_ctrl(fan_data, fan_data->speed[speed_index].ctrl_val);
    fan_data->speed_index = speed_index;
}

static int get_fan_speed_index(struct gpio_fan_data *fan_data)
{
    int ctrl_val = __get_fan_ctrl(fan_data);
    int i;

    for (i = 0; i < fan_data->num_speed; i++)
        if (fan_data->speed[i].ctrl_val == ctrl_val)
            return i;

    dev_warn(&fan_data->pdev->dev,
         "missing speed array entry for GPIO value 0x%x\n", ctrl_val);

    return -EINVAL;
}

static int rpm_to_speed_index(struct gpio_fan_data *fan_data, int rpm)
{
    struct gpio_fan_speed *speed = fan_data->speed;
    int i;

    for (i = 0; i < fan_data->num_speed; i++)
        if (speed[i].rpm >= rpm)
            return i;

    return fan_data->num_speed - 1;
}

static ssize_t show_pwm(struct device *dev,
            struct device_attribute *attr, char *buf)
{
    struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
    u8 pwm = fan_data->speed_index * 255 / (fan_data->num_speed - 1);

    return sprintf(buf, "%d\n", pwm);
}

static ssize_t set_pwm(struct device *dev, struct device_attribute *attr,
               const char *buf, size_t count)
{
    struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
    unsigned long pwm;
    int speed_index;
    int ret = count;

    if (kstrtoul(buf, 10, &pwm) || pwm > 255)
        return -EINVAL;

    mutex_lock(&fan_data->lock);

    if (!fan_data->pwm_enable) {
        ret = -EPERM;
        goto exit_unlock;
    }

    speed_index = DIV_ROUND_UP(pwm * (fan_data->num_speed - 1), 255);
    set_fan_speed(fan_data, speed_index);

exit_unlock:
    mutex_unlock(&fan_data->lock);

    return ret;
}

static ssize_t show_pwm_enable(struct device *dev,
                   struct device_attribute *attr, char *buf)
{
    struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

    return sprintf(buf, "%d\n", fan_data->pwm_enable);
}

static ssize_t set_pwm_enable(struct device *dev, struct device_attribute *attr,
                  const char *buf, size_t count)
{
    struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
    unsigned long val;

    if (kstrtoul(buf, 10, &val) || val > 1)
        return -EINVAL;

    if (fan_data->pwm_enable == val)
        return count;

    mutex_lock(&fan_data->lock);

    fan_data->pwm_enable = val;

    /* Disable manual control mode: set fan at full speed. */
    if (val == 0)
        set_fan_speed(fan_data, fan_data->num_speed - 1);

    mutex_unlock(&fan_data->lock);

    return count;
}

static ssize_t show_pwm_mode(struct device *dev,
                 struct device_attribute *attr, char *buf)
{
    return sprintf(buf, "0\n");
}

static ssize_t show_rpm_min(struct device *dev,
                struct device_attribute *attr, char *buf)
{
    struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

    return sprintf(buf, "%d\n", fan_data->speed[0].rpm);
}

static ssize_t show_rpm_max(struct device *dev,
                struct device_attribute *attr, char *buf)
{
    struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

    return sprintf(buf, "%d\n",
               fan_data->speed[fan_data->num_speed - 1].rpm);
}

static ssize_t show_rpm(struct device *dev,
            struct device_attribute *attr, char *buf)
{
    struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

    return sprintf(buf, "%d\n", fan_data->speed[fan_data->speed_index].rpm);
}

static ssize_t set_rpm(struct device *dev, struct device_attribute *attr,
               const char *buf, size_t count)
{
    struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
    unsigned long rpm;
    int ret = count;

    if (kstrtoul(buf, 10, &rpm))
        return -EINVAL;

    mutex_lock(&fan_data->lock);

    if (!fan_data->pwm_enable) {
        ret = -EPERM;
        goto exit_unlock;
    }

    set_fan_speed(fan_data, rpm_to_speed_index(fan_data, rpm));

exit_unlock:
    mutex_unlock(&fan_data->lock);

    return ret;
}

static DEVICE_ATTR(pwm1, S_IRUGO | S_IWUSR, show_pwm, set_pwm);
static DEVICE_ATTR(pwm1_enable, S_IRUGO | S_IWUSR,
           show_pwm_enable, set_pwm_enable);
static DEVICE_ATTR(pwm1_mode, S_IRUGO, show_pwm_mode, NULL);
static DEVICE_ATTR(fan1_min, S_IRUGO, show_rpm_min, NULL);
static DEVICE_ATTR(fan1_max, S_IRUGO, show_rpm_max, NULL);
static DEVICE_ATTR(fan1_input, S_IRUGO, show_rpm, NULL);
static DEVICE_ATTR(fan1_target, S_IRUGO | S_IWUSR, show_rpm, set_rpm);

static struct attribute *gpio_fan_ctrl_attributes[] = {
    &dev_attr_pwm1.attr,
    &dev_attr_pwm1_enable.attr,
    &dev_attr_pwm1_mode.attr,
    &dev_attr_fan1_input.attr,
    &dev_attr_fan1_target.attr,
    &dev_attr_fan1_min.attr,
    &dev_attr_fan1_max.attr,
    NULL
};

static const struct attribute_group gpio_fan_ctrl_group = {
    .attrs = gpio_fan_ctrl_attributes,
};

static int fan_ctrl_init(struct gpio_fan_data *fan_data,
             struct gpio_fan_platform_data *pdata)
{
    struct platform_device *pdev = fan_data->pdev;
    int num_ctrl = pdata->num_ctrl;
    unsigned *ctrl = pdata->ctrl;
    int i, err;

    for (i = 0; i < num_ctrl; i++) {
        err = devm_gpio_request(&pdev->dev, ctrl[i],
                    "GPIO fan control");
        if (err)
            return err;

        err = gpio_direction_output(ctrl[i], gpio_get_value(ctrl[i]));
        if (err)
            return err;
    }

    fan_data->num_ctrl = num_ctrl;
    fan_data->ctrl = ctrl;
    fan_data->num_speed = pdata->num_speed;
    fan_data->speed = pdata->speed;
    fan_data->pwm_enable = true; /* Enable manual fan speed control. */
    fan_data->speed_index = get_fan_speed_index(fan_data);
    if (fan_data->speed_index < 0)
        return -ENODEV;

    err = sysfs_create_group(&pdev->dev.kobj, &gpio_fan_ctrl_group);
    return err;
}

static void fan_ctrl_free(struct gpio_fan_data *fan_data)
{
    struct platform_device *pdev = fan_data->pdev;

    sysfs_remove_group(&pdev->dev.kobj, &gpio_fan_ctrl_group);
}

/*
 * Platform driver.
 */

static ssize_t show_name(struct device *dev,
             struct device_attribute *attr, char *buf)
{
    return sprintf(buf, "gpio-fan\n");
}

static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);


#ifdef CONFIG_OF_GPIO
/*
 * Translate OpenFirmware node properties into platform_data
 */
static int gpio_fan_get_of_pdata(struct device *dev,
                struct gpio_fan_platform_data *pdata)
{
    struct device_node *node;
    struct gpio_fan_speed *speed;
    unsigned *ctrl;
    unsigned i;
    u32 u;
    struct property *prop;
    const __be32 *p;

    node = dev->of_node;

    /* Fill GPIO pin array */
    pdata->num_ctrl = of_gpio_count(node);
    if (!pdata->num_ctrl) {
        dev_err(dev, "gpios DT property empty / missing");
        return -ENODEV;
    }
    ctrl = devm_kzalloc(dev, pdata->num_ctrl * sizeof(unsigned),
                GFP_KERNEL);
    if (!ctrl)
        return -ENOMEM;
    for (i = 0; i < pdata->num_ctrl; i++) {
        int val;

        val = of_get_gpio(node, i);
        if (val < 0)
            return val;
        ctrl[i] = val;
    }
    pdata->ctrl = ctrl;

    /* Get number of RPM/ctrl_val pairs in speed map */
    prop = of_find_property(node, "gpio-fan,speed-map", &i);
    if (!prop) {
        dev_err(dev, "gpio-fan,speed-map DT property missing");
        return -ENODEV;
    }
    i = i / sizeof(u32);
    if (i == 0 || i & 1) {
        dev_err(dev, "gpio-fan,speed-map contains zero/odd number of entries");
        return -ENODEV;
    }
    pdata->num_speed = i / 2;

    /*
     * Populate speed map
     * Speed map is in the form <RPM ctrl_val RPM ctrl_val ...>
     * this needs splitting into pairs to create gpio_fan_speed structs
     */
    speed = devm_kzalloc(dev,
            pdata->num_speed * sizeof(struct gpio_fan_speed),
            GFP_KERNEL);
    if (!speed)
        return -ENOMEM;
    p = NULL;
    for (i = 0; i < pdata->num_speed; i++) {
        p = of_prop_next_u32(prop, p, &u);
        if (!p)
            return -ENODEV;
        speed[i].rpm = u;
        p = of_prop_next_u32(prop, p, &u);
        if (!p)
            return -ENODEV;
        speed[i].ctrl_val = u;
    }
    pdata->speed = speed;

    /* Alarm GPIO if one exists */
    if (of_gpio_named_count(node, "alarm-gpios")) {
        struct gpio_fan_alarm *alarm;
        int val;
        enum of_gpio_flags flags;

        alarm = devm_kzalloc(dev, sizeof(struct gpio_fan_alarm),
                    GFP_KERNEL);
        if (!alarm)
            return -ENOMEM;

        val = of_get_named_gpio_flags(node, "alarm-gpios", 0, &flags);
        if (val < 0)
            return val;
        alarm->gpio = val;
        alarm->active_low = flags & OF_GPIO_ACTIVE_LOW;

        pdata->alarm = alarm;
    }

    return 0;
}

static struct of_device_id of_gpio_fan_match[] __devinitdata = {
    { .compatible = "gpio-fan", },
    {},
};
#endif /* CONFIG_OF_GPIO */

static int __devinit gpio_fan_probe(struct platform_device *pdev)
{
    int err;
    struct gpio_fan_data *fan_data;
    struct gpio_fan_platform_data *pdata = pdev->dev.platform_data;

#ifdef CONFIG_OF_GPIO
    if (!pdata) {
        pdata = devm_kzalloc(&pdev->dev,
                    sizeof(struct gpio_fan_platform_data),
                    GFP_KERNEL);
        if (!pdata)
            return -ENOMEM;

        err = gpio_fan_get_of_pdata(&pdev->dev, pdata);
        if (err)
            return err;
    }
#else /* CONFIG_OF_GPIO */
    if (!pdata)
        return -EINVAL;
#endif /* CONFIG_OF_GPIO */

    fan_data = devm_kzalloc(&pdev->dev, sizeof(struct gpio_fan_data),
                GFP_KERNEL);
    if (!fan_data)
        return -ENOMEM;

    fan_data->pdev = pdev;
    platform_set_drvdata(pdev, fan_data);
    mutex_init(&fan_data->lock);

    /* Configure alarm GPIO if available. */
    if (pdata->alarm) {
        err = fan_alarm_init(fan_data, pdata->alarm);
        if (err)
            return err;
    }

    /* Configure control GPIOs if available. */
    if (pdata->ctrl && pdata->num_ctrl > 0) {
        if (!pdata->speed || pdata->num_speed <= 1) {
            err = -EINVAL;
            goto err_free_alarm;
        }
        err = fan_ctrl_init(fan_data, pdata);
        if (err)
            goto err_free_alarm;
    }

    err = device_create_file(&pdev->dev, &dev_attr_name);
    if (err)
        goto err_free_ctrl;

    /* Make this driver part of hwmon class. */
    fan_data->hwmon_dev = hwmon_device_register(&pdev->dev);
    if (IS_ERR(fan_data->hwmon_dev)) {
        err = PTR_ERR(fan_data->hwmon_dev);
        goto err_remove_name;
    }

    dev_info(&pdev->dev, "GPIO fan initialized\n");

    return 0;

err_remove_name:
    device_remove_file(&pdev->dev, &dev_attr_name);
err_free_ctrl:
    if (fan_data->ctrl)
        fan_ctrl_free(fan_data);
err_free_alarm:
    if (fan_data->alarm)
        fan_alarm_free(fan_data);
    return err;
}

static int __devexit gpio_fan_remove(struct platform_device *pdev)
{
    struct gpio_fan_data *fan_data = platform_get_drvdata(pdev);

    hwmon_device_unregister(fan_data->hwmon_dev);
    device_remove_file(&pdev->dev, &dev_attr_name);
    if (fan_data->alarm)
        fan_alarm_free(fan_data);
    if (fan_data->ctrl)
        fan_ctrl_free(fan_data);

    return 0;
}

#ifdef CONFIG_PM_SLEEP
static int gpio_fan_suspend(struct device *dev)
{
    struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

    if (fan_data->ctrl) {
        fan_data->resume_speed = fan_data->speed_index;
        set_fan_speed(fan_data, 0);
    }

    return 0;
}

static int gpio_fan_resume(struct device *dev)
{
    struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

    if (fan_data->ctrl)
        set_fan_speed(fan_data, fan_data->resume_speed);

    return 0;
}

static SIMPLE_DEV_PM_OPS(gpio_fan_pm, gpio_fan_suspend, gpio_fan_resume);
#define GPIO_FAN_PM &gpio_fan_pm
#else
#define GPIO_FAN_PM NULL
#endif

static struct platform_driver gpio_fan_driver = {
    .probe      = gpio_fan_probe,
    .remove     = __devexit_p(gpio_fan_remove),
    .driver = {
        .name   = "gpio-fan",
        .pm = GPIO_FAN_PM,
#ifdef CONFIG_OF_GPIO
        .of_match_table = of_match_ptr(of_gpio_fan_match),
#endif
    },
};

module_platform_driver(gpio_fan_driver);

MODULE_AUTHOR("Simon Guinot <[email protected]>");
MODULE_DESCRIPTION("GPIO FAN driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:gpio-fan");