lcd.c

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

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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

#if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \
               defined(CONFIG_LCD_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 lcd power as well ...
 */
static int fb_notifier_callback(struct notifier_block *self,
                 unsigned long event, void *data)
{
    struct lcd_device *ld;
    struct fb_event *evdata = data;

    /* If we aren't interested in this event, skip it immediately ... */
    switch (event) {
    case FB_EVENT_BLANK:
    case FB_EVENT_MODE_CHANGE:
    case FB_EVENT_MODE_CHANGE_ALL:
    case FB_EARLY_EVENT_BLANK:
    case FB_R_EARLY_EVENT_BLANK:
        break;
    default:
        return 0;
    }

    ld = container_of(self, struct lcd_device, fb_notif);
    if (!ld->ops)
        return 0;

    mutex_lock(&ld->ops_lock);
    if (!ld->ops->check_fb || ld->ops->check_fb(ld, evdata->info)) {
        if (event == FB_EVENT_BLANK) {
            if (ld->ops->set_power)
                ld->ops->set_power(ld, *(int *)evdata->data);
        } else if (event == FB_EARLY_EVENT_BLANK) {
            if (ld->ops->early_set_power)
                ld->ops->early_set_power(ld,
                        *(int *)evdata->data);
        } else if (event == FB_R_EARLY_EVENT_BLANK) {
            if (ld->ops->r_early_set_power)
                ld->ops->r_early_set_power(ld,
                        *(int *)evdata->data);
        } else {
            if (ld->ops->set_mode)
                ld->ops->set_mode(ld, evdata->data);
        }
    }
    mutex_unlock(&ld->ops_lock);
    return 0;
}

static int lcd_register_fb(struct lcd_device *ld)
{
    memset(&ld->fb_notif, 0, sizeof(ld->fb_notif));
    ld->fb_notif.notifier_call = fb_notifier_callback;
    return fb_register_client(&ld->fb_notif);
}

static void lcd_unregister_fb(struct lcd_device *ld)
{
    fb_unregister_client(&ld->fb_notif);
}
#else
static int lcd_register_fb(struct lcd_device *ld)
{
    return 0;
}

static inline void lcd_unregister_fb(struct lcd_device *ld)
{
}
#endif /* CONFIG_FB */

static ssize_t lcd_show_power(struct device *dev, struct device_attribute *attr,
        char *buf)
{
    int rc;
    struct lcd_device *ld = to_lcd_device(dev);

    mutex_lock(&ld->ops_lock);
    if (ld->ops && ld->ops->get_power)
        rc = sprintf(buf, "%d\n", ld->ops->get_power(ld));
    else
        rc = -ENXIO;
    mutex_unlock(&ld->ops_lock);

    return rc;
}

static ssize_t lcd_store_power(struct device *dev,
        struct device_attribute *attr, const char *buf, size_t count)
{
    int rc = -ENXIO;
    struct lcd_device *ld = to_lcd_device(dev);
    unsigned long power;

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

    mutex_lock(&ld->ops_lock);
    if (ld->ops && ld->ops->set_power) {
        pr_debug("set power to %lu\n", power);
        ld->ops->set_power(ld, power);
        rc = count;
    }
    mutex_unlock(&ld->ops_lock);

    return rc;
}

static ssize_t lcd_show_contrast(struct device *dev,
        struct device_attribute *attr, char *buf)
{
    int rc = -ENXIO;
    struct lcd_device *ld = to_lcd_device(dev);

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

    return rc;
}

static ssize_t lcd_store_contrast(struct device *dev,
        struct device_attribute *attr, const char *buf, size_t count)
{
    int rc = -ENXIO;
    struct lcd_device *ld = to_lcd_device(dev);
    unsigned long contrast;

    rc = kstrtoul(buf, 0, &contrast);
    if (rc)
        return rc;

    mutex_lock(&ld->ops_lock);
    if (ld->ops && ld->ops->set_contrast) {
        pr_debug("set contrast to %lu\n", contrast);
        ld->ops->set_contrast(ld, contrast);
        rc = count;
    }
    mutex_unlock(&ld->ops_lock);

    return rc;
}

static ssize_t lcd_show_max_contrast(struct device *dev,
        struct device_attribute *attr, char *buf)
{
    struct lcd_device *ld = to_lcd_device(dev);

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

static struct class *lcd_class;

static void lcd_device_release(struct device *dev)
{
    struct lcd_device *ld = to_lcd_device(dev);
    kfree(ld);
}

static struct device_attribute lcd_device_attributes[] = {
    __ATTR(lcd_power, 0644, lcd_show_power, lcd_store_power),
    __ATTR(contrast, 0644, lcd_show_contrast, lcd_store_contrast),
    __ATTR(max_contrast, 0444, lcd_show_max_contrast, NULL),
    __ATTR_NULL,
};

struct lcd_device *lcd_device_register(const char *name, struct device *parent,
        void *devdata, struct lcd_ops *ops)
{
    struct lcd_device *new_ld;
    int rc;

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

    new_ld = kzalloc(sizeof(struct lcd_device), GFP_KERNEL);
    if (!new_ld)
        return ERR_PTR(-ENOMEM);

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

    new_ld->dev.class = lcd_class;
    new_ld->dev.parent = parent;
    new_ld->dev.release = lcd_device_release;
    dev_set_name(&new_ld->dev, name);
    dev_set_drvdata(&new_ld->dev, devdata);

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

    rc = lcd_register_fb(new_ld);
    if (rc) {
        device_unregister(&new_ld->dev);
        return ERR_PTR(rc);
    }

    new_ld->ops = ops;

    return new_ld;
}
EXPORT_SYMBOL(lcd_device_register);

void lcd_device_unregister(struct lcd_device *ld)
{
    if (!ld)
        return;

    mutex_lock(&ld->ops_lock);
    ld->ops = NULL;
    mutex_unlock(&ld->ops_lock);
    lcd_unregister_fb(ld);

    device_unregister(&ld->dev);
}
EXPORT_SYMBOL(lcd_device_unregister);

static void __exit lcd_class_exit(void)
{
    class_destroy(lcd_class);
}

static int __init lcd_class_init(void)
{
    lcd_class = class_create(THIS_MODULE, "lcd");
    if (IS_ERR(lcd_class)) {
        pr_warn("Unable to create backlight class; errno = %ld\n",
            PTR_ERR(lcd_class));
        return PTR_ERR(lcd_class);
    }

    lcd_class->dev_attrs = lcd_device_attributes;
    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(lcd_class_init);
module_exit(lcd_class_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jamey Hicks <[email protected]>, Andrew Zabolotny <[email protected]>");
MODULE_DESCRIPTION("LCD Lowlevel Control Abstraction");