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d1d73578e0
According to the comment describing ops_lock in the definition of struct
backlight_device and when comparing with other functions in backlight.c
the mutex must be hold when checking ops to be non-NULL.
Fixes a problem added by c835ee7f41
("backlight: Add suspend/resume
support to the backlight core") in Jan 2009.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Richard Purdie <rpurdie@linux.intel.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
380 lines
9.6 KiB
C
380 lines
9.6 KiB
C
/*
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* Backlight Lowlevel Control Abstraction
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*
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* Copyright (C) 2003,2004 Hewlett-Packard Company
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*
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/device.h>
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#include <linux/backlight.h>
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#include <linux/notifier.h>
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#include <linux/ctype.h>
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#include <linux/err.h>
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#include <linux/fb.h>
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#include <linux/slab.h>
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#ifdef CONFIG_PMAC_BACKLIGHT
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#include <asm/backlight.h>
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#endif
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#if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \
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defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE))
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/* This callback gets called when something important happens inside a
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* framebuffer driver. We're looking if that important event is blanking,
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* and if it is, we're switching backlight power as well ...
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*/
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static int fb_notifier_callback(struct notifier_block *self,
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unsigned long event, void *data)
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{
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struct backlight_device *bd;
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struct fb_event *evdata = data;
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/* If we aren't interested in this event, skip it immediately ... */
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if (event != FB_EVENT_BLANK && event != FB_EVENT_CONBLANK)
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return 0;
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bd = container_of(self, struct backlight_device, fb_notif);
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mutex_lock(&bd->ops_lock);
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if (bd->ops)
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if (!bd->ops->check_fb ||
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bd->ops->check_fb(bd, evdata->info)) {
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bd->props.fb_blank = *(int *)evdata->data;
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if (bd->props.fb_blank == FB_BLANK_UNBLANK)
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bd->props.state &= ~BL_CORE_FBBLANK;
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else
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bd->props.state |= BL_CORE_FBBLANK;
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backlight_update_status(bd);
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}
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mutex_unlock(&bd->ops_lock);
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return 0;
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}
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static int backlight_register_fb(struct backlight_device *bd)
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{
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memset(&bd->fb_notif, 0, sizeof(bd->fb_notif));
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bd->fb_notif.notifier_call = fb_notifier_callback;
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return fb_register_client(&bd->fb_notif);
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}
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static void backlight_unregister_fb(struct backlight_device *bd)
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{
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fb_unregister_client(&bd->fb_notif);
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}
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#else
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static inline int backlight_register_fb(struct backlight_device *bd)
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{
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return 0;
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}
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static inline void backlight_unregister_fb(struct backlight_device *bd)
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{
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}
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#endif /* CONFIG_FB */
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static void backlight_generate_event(struct backlight_device *bd,
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enum backlight_update_reason reason)
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{
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char *envp[2];
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switch (reason) {
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case BACKLIGHT_UPDATE_SYSFS:
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envp[0] = "SOURCE=sysfs";
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break;
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case BACKLIGHT_UPDATE_HOTKEY:
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envp[0] = "SOURCE=hotkey";
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break;
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default:
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envp[0] = "SOURCE=unknown";
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break;
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}
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envp[1] = NULL;
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kobject_uevent_env(&bd->dev.kobj, KOBJ_CHANGE, envp);
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sysfs_notify(&bd->dev.kobj, NULL, "actual_brightness");
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}
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static ssize_t backlight_show_power(struct device *dev,
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struct device_attribute *attr,char *buf)
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{
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struct backlight_device *bd = to_backlight_device(dev);
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return sprintf(buf, "%d\n", bd->props.power);
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}
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static ssize_t backlight_store_power(struct device *dev,
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struct device_attribute *attr, const char *buf, size_t count)
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{
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int rc;
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struct backlight_device *bd = to_backlight_device(dev);
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unsigned long power;
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rc = strict_strtoul(buf, 0, &power);
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if (rc)
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return rc;
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rc = -ENXIO;
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mutex_lock(&bd->ops_lock);
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if (bd->ops) {
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pr_debug("backlight: set power to %lu\n", power);
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if (bd->props.power != power) {
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bd->props.power = power;
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backlight_update_status(bd);
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}
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rc = count;
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}
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mutex_unlock(&bd->ops_lock);
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return rc;
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}
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static ssize_t backlight_show_brightness(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct backlight_device *bd = to_backlight_device(dev);
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return sprintf(buf, "%d\n", bd->props.brightness);
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}
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static ssize_t backlight_store_brightness(struct device *dev,
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struct device_attribute *attr, const char *buf, size_t count)
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{
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int rc;
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struct backlight_device *bd = to_backlight_device(dev);
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unsigned long brightness;
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rc = strict_strtoul(buf, 0, &brightness);
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if (rc)
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return rc;
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rc = -ENXIO;
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mutex_lock(&bd->ops_lock);
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if (bd->ops) {
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if (brightness > bd->props.max_brightness)
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rc = -EINVAL;
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else {
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pr_debug("backlight: set brightness to %lu\n",
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brightness);
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bd->props.brightness = brightness;
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backlight_update_status(bd);
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rc = count;
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}
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}
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mutex_unlock(&bd->ops_lock);
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backlight_generate_event(bd, BACKLIGHT_UPDATE_SYSFS);
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return rc;
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}
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static ssize_t backlight_show_max_brightness(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct backlight_device *bd = to_backlight_device(dev);
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return sprintf(buf, "%d\n", bd->props.max_brightness);
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}
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static ssize_t backlight_show_actual_brightness(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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int rc = -ENXIO;
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struct backlight_device *bd = to_backlight_device(dev);
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mutex_lock(&bd->ops_lock);
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if (bd->ops && bd->ops->get_brightness)
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rc = sprintf(buf, "%d\n", bd->ops->get_brightness(bd));
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mutex_unlock(&bd->ops_lock);
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return rc;
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}
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static struct class *backlight_class;
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static int backlight_suspend(struct device *dev, pm_message_t state)
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{
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struct backlight_device *bd = to_backlight_device(dev);
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mutex_lock(&bd->ops_lock);
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if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
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bd->props.state |= BL_CORE_SUSPENDED;
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backlight_update_status(bd);
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}
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mutex_unlock(&bd->ops_lock);
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return 0;
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}
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static int backlight_resume(struct device *dev)
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{
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struct backlight_device *bd = to_backlight_device(dev);
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mutex_lock(&bd->ops_lock);
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if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
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bd->props.state &= ~BL_CORE_SUSPENDED;
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backlight_update_status(bd);
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}
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mutex_unlock(&bd->ops_lock);
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return 0;
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}
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static void bl_device_release(struct device *dev)
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{
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struct backlight_device *bd = to_backlight_device(dev);
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kfree(bd);
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}
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static struct device_attribute bl_device_attributes[] = {
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__ATTR(bl_power, 0644, backlight_show_power, backlight_store_power),
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__ATTR(brightness, 0644, backlight_show_brightness,
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backlight_store_brightness),
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__ATTR(actual_brightness, 0444, backlight_show_actual_brightness,
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NULL),
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__ATTR(max_brightness, 0444, backlight_show_max_brightness, NULL),
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__ATTR_NULL,
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};
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/**
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* backlight_force_update - tell the backlight subsystem that hardware state
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* has changed
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* @bd: the backlight device to update
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*
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* Updates the internal state of the backlight in response to a hardware event,
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* and generate a uevent to notify userspace
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*/
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void backlight_force_update(struct backlight_device *bd,
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enum backlight_update_reason reason)
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{
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mutex_lock(&bd->ops_lock);
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if (bd->ops && bd->ops->get_brightness)
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bd->props.brightness = bd->ops->get_brightness(bd);
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mutex_unlock(&bd->ops_lock);
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backlight_generate_event(bd, reason);
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}
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EXPORT_SYMBOL(backlight_force_update);
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/**
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* backlight_device_register - create and register a new object of
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* backlight_device class.
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* @name: the name of the new object(must be the same as the name of the
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* respective framebuffer device).
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* @parent: a pointer to the parent device
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* @devdata: an optional pointer to be stored for private driver use. The
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* methods may retrieve it by using bl_get_data(bd).
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* @ops: the backlight operations structure.
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*
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* Creates and registers new backlight device. Returns either an
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* ERR_PTR() or a pointer to the newly allocated device.
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*/
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struct backlight_device *backlight_device_register(const char *name,
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struct device *parent, void *devdata, const struct backlight_ops *ops,
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const struct backlight_properties *props)
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{
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struct backlight_device *new_bd;
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int rc;
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pr_debug("backlight_device_register: name=%s\n", name);
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new_bd = kzalloc(sizeof(struct backlight_device), GFP_KERNEL);
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if (!new_bd)
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return ERR_PTR(-ENOMEM);
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mutex_init(&new_bd->update_lock);
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mutex_init(&new_bd->ops_lock);
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new_bd->dev.class = backlight_class;
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new_bd->dev.parent = parent;
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new_bd->dev.release = bl_device_release;
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dev_set_name(&new_bd->dev, name);
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dev_set_drvdata(&new_bd->dev, devdata);
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/* Set default properties */
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if (props)
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memcpy(&new_bd->props, props,
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sizeof(struct backlight_properties));
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rc = device_register(&new_bd->dev);
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if (rc) {
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kfree(new_bd);
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return ERR_PTR(rc);
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}
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rc = backlight_register_fb(new_bd);
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if (rc) {
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device_unregister(&new_bd->dev);
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return ERR_PTR(rc);
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}
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new_bd->ops = ops;
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#ifdef CONFIG_PMAC_BACKLIGHT
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mutex_lock(&pmac_backlight_mutex);
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if (!pmac_backlight)
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pmac_backlight = new_bd;
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mutex_unlock(&pmac_backlight_mutex);
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#endif
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return new_bd;
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}
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EXPORT_SYMBOL(backlight_device_register);
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/**
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* backlight_device_unregister - unregisters a backlight device object.
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* @bd: the backlight device object to be unregistered and freed.
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*
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* Unregisters a previously registered via backlight_device_register object.
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*/
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void backlight_device_unregister(struct backlight_device *bd)
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{
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if (!bd)
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return;
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#ifdef CONFIG_PMAC_BACKLIGHT
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mutex_lock(&pmac_backlight_mutex);
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if (pmac_backlight == bd)
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pmac_backlight = NULL;
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mutex_unlock(&pmac_backlight_mutex);
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#endif
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mutex_lock(&bd->ops_lock);
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bd->ops = NULL;
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mutex_unlock(&bd->ops_lock);
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backlight_unregister_fb(bd);
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device_unregister(&bd->dev);
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}
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EXPORT_SYMBOL(backlight_device_unregister);
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static void __exit backlight_class_exit(void)
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{
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class_destroy(backlight_class);
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}
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static int __init backlight_class_init(void)
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{
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backlight_class = class_create(THIS_MODULE, "backlight");
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if (IS_ERR(backlight_class)) {
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printk(KERN_WARNING "Unable to create backlight class; errno = %ld\n",
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PTR_ERR(backlight_class));
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return PTR_ERR(backlight_class);
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}
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backlight_class->dev_attrs = bl_device_attributes;
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backlight_class->suspend = backlight_suspend;
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backlight_class->resume = backlight_resume;
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return 0;
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}
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/*
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* if this is compiled into the kernel, we need to ensure that the
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* class is registered before users of the class try to register lcd's
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*/
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postcore_initcall(backlight_class_init);
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module_exit(backlight_class_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
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MODULE_DESCRIPTION("Backlight Lowlevel Control Abstraction");
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