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/*
* Miscellaneous procedures for dealing with the PowerMac hardware.
* Contains support for the backlight.
*
* Copyright (C) 2000 Benjamin Herrenschmidt
* Copyright (C) 2006 Michael Hanselmann <linux-kernel@hansmi.ch>
*
*/
#include <linux/kernel.h>
#include <linux/fb.h>
#include <linux/backlight.h>
#include <asm/prom.h>
#include <asm/backlight.h>
#define OLD_BACKLIGHT_MAX 15
static void pmac_backlight_key_worker(void *data);
static DECLARE_WORK(pmac_backlight_key_work, pmac_backlight_key_worker, NULL);
/* Although this variable is used in interrupt context, it makes no sense to
* protect it. No user is able to produce enough key events per second and
* notice the errors that might happen.
*/
static int pmac_backlight_key_queued;
/* Protect the pmac_backlight variable */
DEFINE_MUTEX(pmac_backlight_mutex);
/* Main backlight storage
*
* Backlight drivers in this variable are required to have the "props"
* attribute set and to have an update_status function.
*
* We can only store one backlight here, but since Apple laptops have only one
* internal display, it doesn't matter. Other backlight drivers can be used
* independently.
*
* Lock ordering:
* pmac_backlight_mutex (global, main backlight)
* pmac_backlight->sem (backlight class)
*/
struct backlight_device *pmac_backlight;
int pmac_has_backlight_type(const char *type)
{
struct device_node* bk_node = find_devices("backlight");
if (bk_node) {
char *prop = get_property(bk_node, "backlight-control", NULL);
if (prop && strncmp(prop, type, strlen(type)) == 0)
return 1;
}
return 0;
}
int pmac_backlight_curve_lookup(struct fb_info *info, int value)
{
int level = (FB_BACKLIGHT_LEVELS - 1);
if (info && info->bl_dev) {
int i, max = 0;
/* Look for biggest value */
for (i = 0; i < FB_BACKLIGHT_LEVELS; i++)
max = max((int)info->bl_curve[i], max);
/* Look for nearest value */
for (i = 0; i < FB_BACKLIGHT_LEVELS; i++) {
int diff = abs(info->bl_curve[i] - value);
if (diff < max) {
max = diff;
level = i;
}
}
}
return level;
}
static void pmac_backlight_key_worker(void *data)
{
mutex_lock(&pmac_backlight_mutex);
if (pmac_backlight) {
struct backlight_properties *props;
int brightness;
down(&pmac_backlight->sem);
props = pmac_backlight->props;
brightness = props->brightness +
((pmac_backlight_key_queued?-1:1) *
(props->max_brightness / 15));
if (brightness < 0)
brightness = 0;
else if (brightness > props->max_brightness)
brightness = props->max_brightness;
props->brightness = brightness;
props->update_status(pmac_backlight);
up(&pmac_backlight->sem);
}
mutex_unlock(&pmac_backlight_mutex);
}
void pmac_backlight_key(int direction)
{
/* we can receive multiple interrupts here, but the scheduled work
* will run only once, with the last value
*/
pmac_backlight_key_queued = direction;
schedule_work(&pmac_backlight_key_work);
}
int pmac_backlight_set_legacy_brightness(int brightness)
{
int error = -ENXIO;
mutex_lock(&pmac_backlight_mutex);
if (pmac_backlight) {
struct backlight_properties *props;
down(&pmac_backlight->sem);
props = pmac_backlight->props;
props->brightness = brightness *
(props->max_brightness + 1) /
(OLD_BACKLIGHT_MAX + 1);
if (props->brightness > props->max_brightness)
props->brightness = props->max_brightness;
else if (props->brightness < 0)
props->brightness = 0;
props->update_status(pmac_backlight);
up(&pmac_backlight->sem);
error = 0;
}
mutex_unlock(&pmac_backlight_mutex);
return error;
}
int pmac_backlight_get_legacy_brightness()
{
int result = -ENXIO;
mutex_lock(&pmac_backlight_mutex);
if (pmac_backlight) {
struct backlight_properties *props;
down(&pmac_backlight->sem);
props = pmac_backlight->props;
result = props->brightness *
(OLD_BACKLIGHT_MAX + 1) /
(props->max_brightness + 1);
up(&pmac_backlight->sem);
}
mutex_unlock(&pmac_backlight_mutex);
return result;
}
EXPORT_SYMBOL_GPL(pmac_backlight);
EXPORT_SYMBOL_GPL(pmac_backlight_mutex);
EXPORT_SYMBOL_GPL(pmac_has_backlight_type);
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