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/*
 * Backlight code for via-pmu
 *
 * Copyright (C) 1998 Paul Mackerras and Fabio Riccardi.
 * Copyright (C) 2001-2002 Benjamin Herrenschmidt
 * Copyright (C) 2006      Michael Hanselmann <linux-kernel@hansmi.ch>
 *
 */
 
#include <asm/ptrace.h>
#include <linux/adb.h>
#include <linux/pmu.h>
#include <asm/backlight.h>
#include <asm/prom.h>
 
#define MAX_PMU_LEVEL 0xFF
 
static struct backlight_ops pmu_backlight_data;
static DEFINE_SPINLOCK(pmu_backlight_lock);
static int sleeping;
static u8 bl_curve[FB_BACKLIGHT_LEVELS];
 
static void pmu_backlight_init_curve(u8 off, u8 min, u8 max)
{
	unsigned int i, flat, count, range = (max - min);
 
	bl_curve[0] = off;
 
	for (flat = 1; flat < (FB_BACKLIGHT_LEVELS / 16); ++flat)
		bl_curve[flat] = min;
 
	count = FB_BACKLIGHT_LEVELS * 15 / 16;
	for (i = 0; i < count; ++i)
		bl_curve[flat + i] = min + (range * (i + 1) / count);
}
 
static int pmu_backlight_curve_lookup(int value)
{
	int level = (FB_BACKLIGHT_LEVELS - 1);
	int i, max = 0;
 
	/* Look for biggest value */
	for (i = 0; i < FB_BACKLIGHT_LEVELS; i++)
		max = max((int)bl_curve[i], max);
 
	/* Look for nearest value */
	for (i = 0; i < FB_BACKLIGHT_LEVELS; i++) {
		int diff = abs(bl_curve[i] - value);
		if (diff < max) {
			max = diff;
			level = i;
		}
	}
	return level;
}
 
static int pmu_backlight_get_level_brightness(int level)
{
	int pmulevel;
 
	/* Get and convert the value */
	pmulevel = bl_curve[level] * FB_BACKLIGHT_MAX / MAX_PMU_LEVEL;
	if (pmulevel < 0)
		pmulevel = 0;
	else if (pmulevel > MAX_PMU_LEVEL)
		pmulevel = MAX_PMU_LEVEL;
 
	return pmulevel;
}
 
static int pmu_backlight_update_status(struct backlight_device *bd)
{
	struct adb_request req;
	unsigned long flags;
	int level = bd->props.brightness;
 
	spin_lock_irqsave(&pmu_backlight_lock, flags);
 
	/* Don't update brightness when sleeping */
	if (sleeping)
		goto out;
 
	if (bd->props.power != FB_BLANK_UNBLANK ||
	    bd->props.fb_blank != FB_BLANK_UNBLANK)
		level = 0;
 
	if (level > 0) {
		int pmulevel = pmu_backlight_get_level_brightness(level);
 
		pmu_request(&req, NULL, 2, PMU_BACKLIGHT_BRIGHT, pmulevel);
		pmu_wait_complete(&req);
 
		pmu_request(&req, NULL, 2, PMU_POWER_CTRL,
			PMU_POW_BACKLIGHT | PMU_POW_ON);
		pmu_wait_complete(&req);
	} else {
		pmu_request(&req, NULL, 2, PMU_POWER_CTRL,
			PMU_POW_BACKLIGHT | PMU_POW_OFF);
		pmu_wait_complete(&req);
	}
 
out:
	spin_unlock_irqrestore(&pmu_backlight_lock, flags);
 
	return 0;
}
 
static int pmu_backlight_get_brightness(struct backlight_device *bd)
{
	return bd->props.brightness;
}
 
static struct backlight_ops pmu_backlight_data = {
	.get_brightness	= pmu_backlight_get_brightness,
	.update_status	= pmu_backlight_update_status,
 
};
 
#ifdef CONFIG_PM
void pmu_backlight_set_sleep(int sleep)
{
	unsigned long flags;
 
	spin_lock_irqsave(&pmu_backlight_lock, flags);
	sleeping = sleep;
	spin_unlock_irqrestore(&pmu_backlight_lock, flags);
}
#endif /* CONFIG_PM */
 
void __init pmu_backlight_init()
{
	struct backlight_device *bd;
	char name[10];
	int level, autosave;
 
	/* Special case for the old PowerBook since I can't test on it */
	autosave =
		machine_is_compatible("AAPL,3400/2400") ||
		machine_is_compatible("AAPL,3500");
 
	if (!autosave &&
	    !pmac_has_backlight_type("pmu") &&
	    !machine_is_compatible("AAPL,PowerBook1998") &&
	    !machine_is_compatible("PowerBook1,1"))
		return;
 
	snprintf(name, sizeof(name), "pmubl");
 
	bd = backlight_device_register(name, NULL, NULL, &pmu_backlight_data);
	if (IS_ERR(bd)) {
		printk("pmubl: Backlight registration failed\n");
		goto error;
	}
	bd->props.max_brightness = FB_BACKLIGHT_LEVELS - 1;
	pmu_backlight_init_curve(0x7F, 0x46, 0x0E);
 
	level = bd->props.max_brightness;
 
	if (autosave) {
		/* read autosaved value if available */
		struct adb_request req;
		pmu_request(&req, NULL, 2, 0xd9, 0);
		pmu_wait_complete(&req);
 
		level = pmu_backlight_curve_lookup(
				(req.reply[0] >> 4) *
				bd->props.max_brightness / 15);
	}
 
	bd->props.brightness = level;
	bd->props.power = FB_BLANK_UNBLANK;
	backlight_update_status(bd);
 
	printk("pmubl: Backlight initialized (%s)\n", name);
 
	return;
 
error:
	return;
}