/*
 * Backlight Lowlevel Control Abstraction
 *
 * Copyright (C) 2003,2004 Hewlett-Packard Company
 *
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/backlight.h>
#include <linux/notifier.h>
#include <linux/ctype.h>
#include <linux/err.h>
#include <linux/fb.h>
#include <linux/slab.h>

#ifdef CONFIG_PMAC_BACKLIGHT
#include <asm/backlight.h>
#endif

#if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \
                           defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE))
/* This callback gets called when something important happens inside a
 * framebuffer driver. We're looking if that important event is blanking,
 * and if it is, we're switching backlight power as well ...
 */
static int fb_notifier_callback(struct notifier_block *self,
                                unsigned long event, void *data)
{
        struct backlight_device *bd;
        struct fb_event *evdata = data;

        /* If we aren't interested in this event, skip it immediately ... */
        if (event != FB_EVENT_BLANK && event != FB_EVENT_CONBLANK)
                return 0;

        bd = container_of(self, struct backlight_device, fb_notif);
        mutex_lock(&bd->ops_lock);
        if (bd->ops)
                if (!bd->ops->check_fb ||
                    bd->ops->check_fb(bd, evdata->info)) {
                        bd->props.fb_blank = *(int *)evdata->data;
                        if (bd->props.fb_blank == FB_BLANK_UNBLANK)
                                bd->props.state &= ~BL_CORE_FBBLANK;
                        else
                                bd->props.state |= BL_CORE_FBBLANK;
                        backlight_update_status(bd);
                }
        mutex_unlock(&bd->ops_lock);
        return 0;
}

static int backlight_register_fb(struct backlight_device *bd)
{
        memset(&bd->fb_notif, 0, sizeof(bd->fb_notif));
        bd->fb_notif.notifier_call = fb_notifier_callback;

        return fb_register_client(&bd->fb_notif);
}

static void backlight_unregister_fb(struct backlight_device *bd)
{
        fb_unregister_client(&bd->fb_notif);
}
#else
static inline int backlight_register_fb(struct backlight_device *bd)
{
        return 0;
}

static inline void backlight_unregister_fb(struct backlight_device *bd)
{
}
#endif /* CONFIG_FB */

static void backlight_generate_event(struct backlight_device *bd,
                                     enum backlight_update_reason reason)
{
        char *envp[2];

        switch (reason) {
        case BACKLIGHT_UPDATE_SYSFS:
                envp[0] = "SOURCE=sysfs";
                break;
        case BACKLIGHT_UPDATE_HOTKEY:
                envp[0] = "SOURCE=hotkey";
                break;
        default:
                envp[0] = "SOURCE=unknown";
                break;
        }
        envp[1] = NULL;
        kobject_uevent_env(&bd->dev.kobj, KOBJ_CHANGE, envp);
        sysfs_notify(&bd->dev.kobj, NULL, "actual_brightness");
}

static ssize_t backlight_show_power(struct device *dev,
                struct device_attribute *attr,char *buf)
{
        struct backlight_device *bd = to_backlight_device(dev);

        return sprintf(buf, "%d\n", bd->props.power);
}

static ssize_t backlight_store_power(struct device *dev,
                struct device_attribute *attr, const char *buf, size_t count)
{
        int rc;
        struct backlight_device *bd = to_backlight_device(dev);
        unsigned long power;

        rc = strict_strtoul(buf, 0, &power);
        if (rc)
                return rc;

        rc = -ENXIO;
        mutex_lock(&bd->ops_lock);
        if (bd->ops) {
                pr_debug("backlight: set power to %lu\n", power);
                if (bd->props.power != power) {
                        bd->props.power = power;
                        backlight_update_status(bd);
                }
                rc = count;
        }
        mutex_unlock(&bd->ops_lock);

        return rc;
}

static ssize_t backlight_show_brightness(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct backlight_device *bd = to_backlight_device(dev);

        return sprintf(buf, "%d\n", bd->props.brightness);
}

static ssize_t backlight_store_brightness(struct device *dev,
                struct device_attribute *attr, const char *buf, size_t count)
{
        int rc;
        struct backlight_device *bd = to_backlight_device(dev);
        unsigned long brightness;

        rc = strict_strtoul(buf, 0, &brightness);
        if (rc)
                return rc;

        rc = -ENXIO;

        mutex_lock(&bd->ops_lock);
        if (bd->ops) {
                if (brightness > bd->props.max_brightness)
                        rc = -EINVAL;
                else {
                        pr_debug("backlight: set brightness to %lu\n",
                                 brightness);
                        bd->props.brightness = brightness;
                        backlight_update_status(bd);
                        rc = count;
                }
        }
        mutex_unlock(&bd->ops_lock);

        backlight_generate_event(bd, BACKLIGHT_UPDATE_SYSFS);

        return rc;
}

static ssize_t backlight_show_max_brightness(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct backlight_device *bd = to_backlight_device(dev);

        return sprintf(buf, "%d\n", bd->props.max_brightness);
}

static ssize_t backlight_show_actual_brightness(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        int rc = -ENXIO;
        struct backlight_device *bd = to_backlight_device(dev);

        mutex_lock(&bd->ops_lock);
        if (bd->ops && bd->ops->get_brightness)
                rc = sprintf(buf, "%d\n", bd->ops->get_brightness(bd));
        mutex_unlock(&bd->ops_lock);

        return rc;
}

static struct class *backlight_class;

static int backlight_suspend(struct device *dev, pm_message_t state)
{
        struct backlight_device *bd = to_backlight_device(dev);

        mutex_lock(&bd->ops_lock);
        if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
                bd->props.state |= BL_CORE_SUSPENDED;
                backlight_update_status(bd);
        }
        mutex_unlock(&bd->ops_lock);

        return 0;
}

static int backlight_resume(struct device *dev)
{
        struct backlight_device *bd = to_backlight_device(dev);

        mutex_lock(&bd->ops_lock);
        if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
                bd->props.state &= ~BL_CORE_SUSPENDED;
                backlight_update_status(bd);
        }
        mutex_unlock(&bd->ops_lock);

        return 0;
}

static void bl_device_release(struct device *dev)
{
        struct backlight_device *bd = to_backlight_device(dev);
        kfree(bd);
}

static struct device_attribute bl_device_attributes[] = {
        __ATTR(bl_power, 0644, backlight_show_power, backlight_store_power),
        __ATTR(brightness, 0644, backlight_show_brightness,
                     backlight_store_brightness),
        __ATTR(actual_brightness, 0444, backlight_show_actual_brightness,
                     NULL),
        __ATTR(max_brightness, 0444, backlight_show_max_brightness, NULL),
        __ATTR_NULL,
};

/**
 * backlight_force_update - tell the backlight subsystem that hardware state
 *   has changed
 * @bd: the backlight device to update
 *
 * Updates the internal state of the backlight in response to a hardware event,
 * and generate a uevent to notify userspace
 */
void backlight_force_update(struct backlight_device *bd,
                            enum backlight_update_reason reason)
{
        mutex_lock(&bd->ops_lock);
        if (bd->ops && bd->ops->get_brightness)
                bd->props.brightness = bd->ops->get_brightness(bd);
        mutex_unlock(&bd->ops_lock);
        backlight_generate_event(bd, reason);
}
EXPORT_SYMBOL(backlight_force_update);

/**
 * backlight_device_register - create and register a new object of
 *   backlight_device class.
 * @name: the name of the new object(must be the same as the name of the
 *   respective framebuffer device).
 * @parent: a pointer to the parent device
 * @devdata: an optional pointer to be stored for private driver use. The
 *   methods may retrieve it by using bl_get_data(bd).
 * @ops: the backlight operations structure.
 *
 * Creates and registers new backlight device. Returns either an
 * ERR_PTR() or a pointer to the newly allocated device.
 */
struct backlight_device *backlight_device_register(const char *name,
        struct device *parent, void *devdata, const struct backlight_ops *ops,
        const struct backlight_properties *props)
{
        struct backlight_device *new_bd;
        int rc;

        pr_debug("backlight_device_register: name=%s\n", name);

        new_bd = kzalloc(sizeof(struct backlight_device), GFP_KERNEL);
        if (!new_bd)
                return ERR_PTR(-ENOMEM);

        mutex_init(&new_bd->update_lock);
        mutex_init(&new_bd->ops_lock);

        new_bd->dev.class = backlight_class;
        new_bd->dev.parent = parent;
        new_bd->dev.release = bl_device_release;
        dev_set_name(&new_bd->dev, name);
        dev_set_drvdata(&new_bd->dev, devdata);

        /* Set default properties */
        if (props)
                memcpy(&new_bd->props, props,
                       sizeof(struct backlight_properties));

        rc = device_register(&new_bd->dev);
        if (rc) {
                kfree(new_bd);
                return ERR_PTR(rc);
        }

        rc = backlight_register_fb(new_bd);
        if (rc) {
                device_unregister(&new_bd->dev);
                return ERR_PTR(rc);
        }

        new_bd->ops = ops;

#ifdef CONFIG_PMAC_BACKLIGHT
        mutex_lock(&pmac_backlight_mutex);
        if (!pmac_backlight)
                pmac_backlight = new_bd;
        mutex_unlock(&pmac_backlight_mutex);
#endif

        return new_bd;
}
EXPORT_SYMBOL(backlight_device_register);

/**
 * backlight_device_unregister - unregisters a backlight device object.
 * @bd: the backlight device object to be unregistered and freed.
 *
 * Unregisters a previously registered via backlight_device_register object.
 */
void backlight_device_unregister(struct backlight_device *bd)
{
        if (!bd)
                return;

#ifdef CONFIG_PMAC_BACKLIGHT
        mutex_lock(&pmac_backlight_mutex);
        if (pmac_backlight == bd)
                pmac_backlight = NULL;
        mutex_unlock(&pmac_backlight_mutex);
#endif
        mutex_lock(&bd->ops_lock);
        bd->ops = NULL;
        mutex_unlock(&bd->ops_lock);

        backlight_unregister_fb(bd);
        device_unregister(&bd->dev);
}
EXPORT_SYMBOL(backlight_device_unregister);

static void __exit backlight_class_exit(void)
{
        class_destroy(backlight_class);
}

static int __init backlight_class_init(void)
{
        backlight_class = class_create(THIS_MODULE, "backlight");
        if (IS_ERR(backlight_class)) {
                printk(KERN_WARNING "Unable to create backlight class; errno = %ld\n",
                                PTR_ERR(backlight_class));
                return PTR_ERR(backlight_class);
        }

        backlight_class->dev_attrs = bl_device_attributes;
        backlight_class->suspend = backlight_suspend;
        backlight_class->resume = backlight_resume;
        return 0;
}

/*
 * if this is compiled into the kernel, we need to ensure that the
 * class is registered before users of the class try to register lcd's
 */
postcore_initcall(backlight_class_init);
module_exit(backlight_class_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
MODULE_DESCRIPTION("Backlight Lowlevel Control Abstraction");