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via-pmu-backlight.c

/*
 * 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;
}

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