/*
 * gpio-fan.c - Hwmon driver for fans connected to GPIO lines.
 *
 * Copyright (C) 2010 LaCie
 *
 * Author: Simon Guinot <sguinot@lacie.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.
 *
 * 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>

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
        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 = gpio_request(alarm->gpio, "GPIO fan alarm");
        if (err)
                return err;

        err = gpio_direction_input(alarm->gpio);
        if (err)
                goto err_free_gpio;

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

        /*
         * 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 = request_irq(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);
err_free_gpio:
        gpio_free(alarm->gpio);

        return err;
}

static void fan_alarm_free(struct gpio_fan_data *fan_data)
{
        struct platform_device *pdev = fan_data->pdev;
        int alarm_irq = gpio_to_irq(fan_data->alarm->gpio);

        if (alarm_irq >= 0)
                free_irq(alarm_irq, fan_data);
        device_remove_file(&pdev->dev, &dev_attr_fan1_alarm);
        gpio_free(fan_data->alarm->gpio);
}

/*
 * 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 = gpio_request(ctrl[i], "GPIO fan control");
                if (err)
                        goto err_free_gpio;

                err = gpio_direction_output(ctrl[i], gpio_get_value(ctrl[i]));
                if (err) {
                        gpio_free(ctrl[i]);
                        goto err_free_gpio;
                }
        }

        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) {
                err = -ENODEV;
                goto err_free_gpio;
        }

        err = sysfs_create_group(&pdev->dev.kobj, &gpio_fan_ctrl_group);
        if (err)
                goto err_free_gpio;

        return 0;

err_free_gpio:
        for (i = i - 1; i >= 0; i--)
                gpio_free(ctrl[i]);

        return err;
}

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

        sysfs_remove_group(&pdev->dev.kobj, &gpio_fan_ctrl_group);
        for (i = 0; i < fan_data->num_ctrl; i++)
                gpio_free(fan_data->ctrl[i]);
}

/*
 * 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);

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;

        if (!pdata)
                return -EINVAL;

        fan_data = kzalloc(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)
                        goto err_free_data;
        }

        /* 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);
err_free_data:
        platform_set_drvdata(pdev, NULL);
        kfree(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);
        kfree(fan_data);

        return 0;
}

#ifdef CONFIG_PM
static int gpio_fan_suspend(struct platform_device *pdev, pm_message_t state)
{
        struct gpio_fan_data *fan_data = platform_get_drvdata(pdev);

        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 platform_device *pdev)
{
        struct gpio_fan_data *fan_data = platform_get_drvdata(pdev);

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

        return 0;
}
#else
#define gpio_fan_suspend NULL
#define gpio_fan_resume NULL
#endif

static struct platform_driver gpio_fan_driver = {
        .probe          = gpio_fan_probe,
        .remove         = __devexit_p(gpio_fan_remove),
        .suspend        = gpio_fan_suspend,
        .resume         = gpio_fan_resume,
        .driver = {
                .name   = "gpio-fan",
        },
};

module_platform_driver(gpio_fan_driver);

MODULE_AUTHOR("Simon Guinot <sguinot@lacie.com>");
MODULE_DESCRIPTION("GPIO FAN driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:gpio-fan");