linux-stable/drivers/video/backlight/backlight.c
Matthew Garrett 325253a6b2 backlight: Allow drivers to update the core, and generate events on changes
Certain hardware will send us events when the backlight brightness
changes. Add a function to update the value in the core, and
additionally send a uevent so that userspace can pop up appropriate
UI. The uevents are flagged depending on whether the update originated
in the kernel or from userspace, making it easier to only display UI
at the appropriate time.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
2009-09-21 21:03:58 +01:00

371 lines
9.3 KiB
C

/*
* 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>
#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(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);
}
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);
if (bd->ops->options & BL_CORE_SUSPENDRESUME) {
mutex_lock(&bd->ops_lock);
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);
if (bd->ops->options & BL_CORE_SUSPENDRESUME) {
mutex_lock(&bd->ops_lock);
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, struct backlight_ops *ops)
{
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);
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");