gma500: implement backlight functionality for Cedartrail devices

Basically a straight cut/paste from the reference driver code then
cleaned up a spot.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 52 insertions, 63 deletions

diff --git a/drivers/gpu/drm/gma500/cdv_device.c b/drivers/gpu/drm/gma500/cdv_device.c
index 62f9b735459b..726bfb7375fc 100644
--- a/drivers/gpu/drm/gma500/cdv_device.c
+++ b/drivers/gpu/drm/gma500/cdv_device.c
@@ -57,8 +57,7 @@ static int cdv_output_init(struct drm_device *dev)
         cdv_intel_crt_init(dev, &dev_priv->mode_dev);
         cdv_intel_lvds_init(dev, &dev_priv->mode_dev);
 
-        /* These bits indicate HDMI not SDVO on CDV, but we don't yet support
-           the HDMI interface */
+        /* These bits indicate HDMI not SDVO on CDV */
         if (REG_READ(SDVOB) & SDVO_DETECTED)
                 cdv_hdmi_init(dev, &dev_priv->mode_dev, SDVOB);
         if (REG_READ(SDVOC) & SDVO_DETECTED)
@@ -69,76 +68,71 @@ static int cdv_output_init(struct drm_device *dev)
 #ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
 
 /*
- *      Poulsbo Backlight Interfaces
+ *      Cedartrail Backlght Interfaces
  */
 
-#define BLC_PWM_PRECISION_FACTOR 100    /* 10000000 */
-#define BLC_PWM_FREQ_CALC_CONSTANT 32
-#define MHz 1000000
-
-#define PSB_BLC_PWM_PRECISION_FACTOR    10
-#define PSB_BLC_MAX_PWM_REG_FREQ        0xFFFE
-#define PSB_BLC_MIN_PWM_REG_FREQ        0x2
-
-#define PSB_BACKLIGHT_PWM_POLARITY_BIT_CLEAR (0xFFFE)
-#define PSB_BACKLIGHT_PWM_CTL_SHIFT     (16)
-
-static int cdv_brightness;
 static struct backlight_device *cdv_backlight_device;
 
-static int cdv_get_brightness(struct backlight_device *bd)
+static int cdv_backlight_combination_mode(struct drm_device *dev)
 {
-        /* return locally cached var instead of HW read (due to DPST etc.) */
-        /* FIXME: ideally return actual value in case firmware fiddled with
-           it */
-        return cdv_brightness;
+        return REG_READ(BLC_PWM_CTL2) & PWM_LEGACY_MODE;
 }
 
-
-static int cdv_backlight_setup(struct drm_device *dev)
+static int cdv_get_brightness(struct backlight_device *bd)
 {
-        struct drm_psb_private *dev_priv = dev->dev_private;
-        unsigned long core_clock;
-        /* u32 bl_max_freq; */
-        /* unsigned long value; */
-        u16 bl_max_freq;
-        uint32_t value;
-        uint32_t blc_pwm_precision_factor;
-
-        /* get bl_max_freq and pol from dev_priv*/
-        if (!dev_priv->lvds_bl) {
-                dev_err(dev->dev, "Has no valid LVDS backlight info\n");
-                return -ENOENT;
-        }
-        bl_max_freq = dev_priv->lvds_bl->freq;
-        blc_pwm_precision_factor = PSB_BLC_PWM_PRECISION_FACTOR;
+        struct drm_device *dev = bl_get_data(bd);
+        u32 val = REG_READ(BLC_PWM_CTL) & BACKLIGHT_DUTY_CYCLE_MASK;
 
-        core_clock = dev_priv->core_freq;
+        if (cdv_backlight_combination_mode(dev)) {
+                u8 lbpc;
 
-        value = (core_clock * MHz) / BLC_PWM_FREQ_CALC_CONSTANT;
-        value *= blc_pwm_precision_factor;
-        value /= bl_max_freq;
-        value /= blc_pwm_precision_factor;
+                val &= ~1;
+                pci_read_config_byte(dev->pdev, 0xF4, &lbpc);
+                val *= lbpc;
+        }
+        return val;
+}
 
-        if (value > (unsigned long long)PSB_BLC_MAX_PWM_REG_FREQ ||
-                 value < (unsigned long long)PSB_BLC_MIN_PWM_REG_FREQ)
-                                return -ERANGE;
-        else {
-                /* FIXME */
+static u32 cdv_get_max_backlight(struct drm_device *dev)
+{
+        u32 max = REG_READ(BLC_PWM_CTL);
+
+        if (max == 0) {
+                DRM_DEBUG_KMS("LVDS Panel PWM value is 0!\n");
+                /* i915 does this, I believe which means that we should not
+                 * smash PWM control as firmware will take control of it. */
+                return 1;
         }
-        return 0;
+
+        max >>= 16;
+        if (cdv_backlight_combination_mode(dev))
+                max *= 0xff;
+        return max;
 }
 
 static int cdv_set_brightness(struct backlight_device *bd)
 {
+        struct drm_device *dev = bl_get_data(bd);
         int level = bd->props.brightness;
+        u32 blc_pwm_ctl;
 
         /* Percentage 1-100% being valid */
         if (level < 1)
                 level = 1;
 
-        /*cdv_intel_lvds_set_brightness(dev, level); FIXME */
-        cdv_brightness = level;
+        if (cdv_backlight_combination_mode(dev)) {
+                u32 max = cdv_get_max_backlight(dev);
+                u8 lbpc;
+
+                lbpc = level * 0xfe / max + 1;
+                level /= lbpc;
+
+                pci_write_config_byte(dev->pdev, 0xF4, lbpc);
+        }
+
+        blc_pwm_ctl = REG_READ(BLC_PWM_CTL) & ~BACKLIGHT_DUTY_CYCLE_MASK;
+        REG_WRITE(BLC_PWM_CTL, (blc_pwm_ctl |
+                                (level << BACKLIGHT_DUTY_CYCLE_SHIFT)));
         return 0;
 }
 
@@ -150,7 +144,6 @@ static const struct backlight_ops cdv_ops = {
 static int cdv_backlight_init(struct drm_device *dev)
 {
         struct drm_psb_private *dev_priv = dev->dev_private;
-        int ret;
         struct backlight_properties props;
 
         memset(&props, 0, sizeof(struct backlight_properties));
@@ -162,14 +155,9 @@ static int cdv_backlight_init(struct drm_device *dev)
         if (IS_ERR(cdv_backlight_device))
                 return PTR_ERR(cdv_backlight_device);
 
-        ret = cdv_backlight_setup(dev);
-        if (ret < 0) {
-                backlight_device_unregister(cdv_backlight_device);
-                cdv_backlight_device = NULL;
-                return ret;
-        }
-        cdv_backlight_device->props.brightness = 100;
-        cdv_backlight_device->props.max_brightness = 100;
+        cdv_backlight_device->props.brightness =
+                        cdv_get_brightness(cdv_backlight_device);
+        cdv_backlight_device->props.max_brightness = cdv_get_max_brightness;
         backlight_update_status(cdv_backlight_device);
         dev_priv->backlight_device = cdv_backlight_device;
         return 0;
@@ -244,11 +232,12 @@ static void cdv_init_pm(struct drm_device *dev)
 static void cdv_errata(struct drm_device *dev)
 {
         /* Disable bonus launch.
-         *      CPU and GPU competes for memory and display misses updates and flickers.
-         *      Worst with dual core, dual displays.
+         *      CPU and GPU competes for memory and display misses updates and
+         *      flickers. Worst with dual core, dual displays.
          *
-         *      Fixes were done to Win 7 gfx driver to disable a feature called Bonus
-         *      Launch to work around the issue, by degrading performance.
+         *      Fixes were done to Win 7 gfx driver to disable a feature called
+         *      Bonus Launch to work around the issue, by degrading
+         *      performance.
          */
          CDV_MSG_WRITE32(3, 0x30, 0x08027108);
 }