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// SPDX-License-Identifier: GPL-2.0-only
/*
* 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/backlight.h>
#include <linux/adb.h>
#include <linux/pmu.h>
#include <linux/atomic.h>
#include <linux/export.h>
#include <asm/backlight.h>
#define OLD_BACKLIGHT_MAX 15
static void pmac_backlight_key_worker(struct work_struct *work);
static void pmac_backlight_set_legacy_worker(struct work_struct *work);
static DECLARE_WORK(pmac_backlight_key_work, pmac_backlight_key_worker);
static DECLARE_WORK(pmac_backlight_set_legacy_work, pmac_backlight_set_legacy_worker);
/* Although these variables are used in interrupt context, it makes no sense to
* protect them. No user is able to produce enough key events per second and
* notice the errors that might happen.
*/
static int pmac_backlight_key_queued;
static int pmac_backlight_set_legacy_queued;
/* The via-pmu code allows the backlight to be grabbed, in which case the
* in-kernel control of the brightness needs to be disabled. This should
* only be used by really old PowerBooks.
*/
static atomic_t kernel_backlight_disabled = ATOMIC_INIT(0);
/* Protect the pmac_backlight variable below.
You should hold this lock when using the pmac_backlight pointer to
prevent its potential removal. */
DEFINE_MUTEX(pmac_backlight_mutex);
/* Main backlight storage
*
* Backlight drivers in this variable are required to have the "ops"
* 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.
*
*/
struct backlight_device *pmac_backlight;
int pmac_has_backlight_type(const char *type)
{
struct device_node* bk_node = of_find_node_by_name(NULL, "backlight");
if (bk_node) {
const char *prop = of_get_property(bk_node,
"backlight-control", NULL);
if (prop && strncmp(prop, type, strlen(type)) == 0) {
of_node_put(bk_node);
return 1;
}
of_node_put(bk_node);
}
return 0;
}
static void pmac_backlight_key_worker(struct work_struct *work)
{
if (atomic_read(&kernel_backlight_disabled))
return;
mutex_lock(&pmac_backlight_mutex);
if (pmac_backlight) {
struct backlight_properties *props;
int brightness;
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;
backlight_update_status(pmac_backlight);
}
mutex_unlock(&pmac_backlight_mutex);
}
/* This function is called in interrupt context */
void pmac_backlight_key(int direction)
{
if (atomic_read(&kernel_backlight_disabled))
return;
/* 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);
}
static int __pmac_backlight_set_legacy_brightness(int brightness)
{
int error = -ENXIO;
mutex_lock(&pmac_backlight_mutex);
if (pmac_backlight) {
struct backlight_properties *props;
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;
backlight_update_status(pmac_backlight);
error = 0;
}
mutex_unlock(&pmac_backlight_mutex);
return error;
}
static void pmac_backlight_set_legacy_worker(struct work_struct *work)
{
if (atomic_read(&kernel_backlight_disabled))
return;
__pmac_backlight_set_legacy_brightness(pmac_backlight_set_legacy_queued);
}
/* This function is called in interrupt context */
void pmac_backlight_set_legacy_brightness_pmu(int brightness) {
if (atomic_read(&kernel_backlight_disabled))
return;
pmac_backlight_set_legacy_queued = brightness;
schedule_work(&pmac_backlight_set_legacy_work);
}
int pmac_backlight_set_legacy_brightness(int brightness)
{
return __pmac_backlight_set_legacy_brightness(brightness);
}
int pmac_backlight_get_legacy_brightness(void)
{
int result = -ENXIO;
mutex_lock(&pmac_backlight_mutex);
if (pmac_backlight) {
struct backlight_properties *props;
props = &pmac_backlight->props;
result = props->brightness *
(OLD_BACKLIGHT_MAX + 1) /
(props->max_brightness + 1);
}
mutex_unlock(&pmac_backlight_mutex);
return result;
}
void pmac_backlight_disable(void)
{
atomic_inc(&kernel_backlight_disabled);
}
void pmac_backlight_enable(void)
{
atomic_dec(&kernel_backlight_disabled);
}
EXPORT_SYMBOL_GPL(pmac_backlight);
EXPORT_SYMBOL_GPL(pmac_backlight_mutex);
EXPORT_SYMBOL_GPL(pmac_has_backlight_type);
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