drm/i915: Add port A HPD support for ILK/SNB

ILK/SNB support port A HPD. While HPD is optional on eDP let's at least
try to wite it up so that we might notice if the link has issues.

The eDP spec suggests that if HPD is not wired up, one should poll the
link status instead. We don't even do that currently.

v2: 0 initialize pin_mask/long_mask due to intel_get_hpd_pins() changes
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_irq.c

@@ -45,6 +45,10 @@
  * and related files, but that will be described in separate chapters.
  */
 
+static const u32 hpd_ilk[HPD_NUM_PINS] = {
+	[HPD_PORT_A] = DE_DP_A_HOTPLUG,
+};
+
 static const u32 hpd_ibx[HPD_NUM_PINS] = {
 	[HPD_CRT] = SDE_CRT_HOTPLUG,
 	[HPD_SDVO_B] = SDE_SDVOB_HOTPLUG,
@@ -1272,6 +1276,16 @@ static bool spt_port_hotplug2_long_detect(enum port port, u32 val)
 	}
 }
 
+static bool ilk_port_hotplug_long_detect(enum port port, u32 val)
+{
+	switch (port) {
+	case PORT_A:
+		return val & DIGITAL_PORTA_HOTPLUG_LONG_DETECT;
+	default:
+		return false;
+	}
+}
+
 static bool pch_port_hotplug_long_detect(enum port port, u32 val)
 {
 	switch (port) {
@@ -1870,6 +1884,19 @@ static void ilk_display_irq_handler(struct drm_device *dev, u32 de_iir)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	enum pipe pipe;
+	u32 hotplug_trigger = de_iir & DE_DP_A_HOTPLUG;
+
+	if (hotplug_trigger) {
+		u32 dig_hotplug_reg, pin_mask = 0, long_mask = 0;
+
+		dig_hotplug_reg = I915_READ(DIGITAL_PORT_HOTPLUG_CNTRL);
+		I915_WRITE(DIGITAL_PORT_HOTPLUG_CNTRL, dig_hotplug_reg);
+
+		intel_get_hpd_pins(&pin_mask, &long_mask, hotplug_trigger,
+				   dig_hotplug_reg, hpd_ilk,
+				   ilk_port_hotplug_long_detect);
+		intel_hpd_irq_handler(dev, pin_mask, long_mask);
+	}
 
 	if (de_iir & DE_AUX_CHANNEL_A)
 		dp_aux_irq_handler(dev);
@@ -3111,6 +3138,28 @@ static void spt_hpd_irq_setup(struct drm_device *dev)
 	I915_WRITE(PCH_PORT_HOTPLUG2, hotplug);
 }
 
+static void ilk_hpd_irq_setup(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	u32 hotplug_irqs, hotplug, enabled_irqs;
+
+	hotplug_irqs = DE_DP_A_HOTPLUG;
+	enabled_irqs = intel_hpd_enabled_irqs(dev, hpd_ilk);
+
+	ilk_update_display_irq(dev_priv, hotplug_irqs, enabled_irqs);
+
+	/*
+	 * Enable digital hotplug on the CPU, and configure the DP short pulse
+	 * duration to 2ms (which is the minimum in the Display Port spec)
+	 */
+	hotplug = I915_READ(DIGITAL_PORT_HOTPLUG_CNTRL);
+	hotplug &= ~DIGITAL_PORTA_PULSE_DURATION_MASK;
+	hotplug |= DIGITAL_PORTA_HOTPLUG_ENABLE | DIGITAL_PORTA_PULSE_DURATION_2ms;
+	I915_WRITE(DIGITAL_PORT_HOTPLUG_CNTRL, hotplug);
+
+	ibx_hpd_irq_setup(dev);
+}
+
 static void bxt_hpd_irq_setup(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -3209,8 +3258,9 @@ static int ironlake_irq_postinstall(struct drm_device *dev)
 				DE_AUX_CHANNEL_A |
 				DE_PIPEB_CRC_DONE | DE_PIPEA_CRC_DONE |
 				DE_POISON);
-		extra_mask = DE_PIPEA_VBLANK | DE_PIPEB_VBLANK | DE_PCU_EVENT |
-				DE_PIPEB_FIFO_UNDERRUN | DE_PIPEA_FIFO_UNDERRUN;
+		extra_mask = (DE_PIPEA_VBLANK | DE_PIPEB_VBLANK | DE_PCU_EVENT |
+			      DE_PIPEB_FIFO_UNDERRUN | DE_PIPEA_FIFO_UNDERRUN |
+			      DE_DP_A_HOTPLUG);
 	}
 
 	dev_priv->irq_mask = ~display_mask;
@@ -4226,7 +4276,10 @@ void intel_irq_init(struct drm_i915_private *dev_priv)
 		dev->driver->irq_uninstall = ironlake_irq_uninstall;
 		dev->driver->enable_vblank = ironlake_enable_vblank;
 		dev->driver->disable_vblank = ironlake_disable_vblank;
-		dev_priv->display.hpd_irq_setup = ibx_hpd_irq_setup;
+		if (INTEL_INFO(dev)->gen >= 7)
+			dev_priv->display.hpd_irq_setup = ibx_hpd_irq_setup;
+		else
+			dev_priv->display.hpd_irq_setup = ilk_hpd_irq_setup;
 	} else {
 		if (INTEL_INFO(dev_priv)->gen == 2) {
 			dev->driver->irq_preinstall = i8xx_irq_preinstall;