drm/i915/bxt: DDI Hotplug interrupt setup

In BXT, DDI hotplug control has been moved to CPU from PCH.
This patch adds a new IRQ setup function for BXT which:
1. Checks which HPD ports are requested to be enabled by encoders.
2. Enables those ports in the hot plug control register.
3. Un-masks these port interrupts in the IMR register.
4. Enables these port interrupts in the IER register.

V3: Kept the default HPD filter count to default (500 us) as per
    satheesh's comment
v4: Remove unused HPD filter defines (Damien)
v5: warn if trying to setup HPD on port A (imre)
v6: fix order of definitions for register bitfields (Daniel)
v7: (jani)
- define the size of the hpd_bxt array explicitly for bound checking
- use for_each_intel_encoder instead of open coding it
- fix format/order of definitions for BXT_HOTPLUG_CTL reg bitfields
Reviewed-by: Satheeshakrishna M <satheeshakrishna.m@intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Shashank Sharma <shashank.sharma@intel.com> (v4)
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_irq.c

@@ -88,6 +88,12 @@ static const u32 hpd_status_i915[HPD_NUM_PINS] = { /* i915 and valleyview are th
 	[HPD_PORT_D] = PORTD_HOTPLUG_INT_STATUS
 };
 
+/* BXT hpd list */
+static const u32 hpd_bxt[HPD_NUM_PINS] = {
+	[HPD_PORT_B] = BXT_DE_PORT_HP_DDIB,
+	[HPD_PORT_C] = BXT_DE_PORT_HP_DDIC
+};
+
 /* IIR can theoretically queue up two events. Be paranoid. */
 #define GEN8_IRQ_RESET_NDX(type, which) do { \
 	I915_WRITE(GEN8_##type##_IMR(which), 0xffffffff); \
@@ -3159,6 +3165,42 @@ static void ibx_hpd_irq_setup(struct drm_device *dev)
 	I915_WRITE(PCH_PORT_HOTPLUG, hotplug);
 }
 
+static void bxt_hpd_irq_setup(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_encoder *intel_encoder;
+	u32 hotplug_port = 0;
+	u32 hotplug_ctrl;
+
+	/* Now, enable HPD */
+	for_each_intel_encoder(dev, intel_encoder) {
+		if (dev_priv->hpd_stats[intel_encoder->hpd_pin].hpd_mark
+				== HPD_ENABLED)
+			hotplug_port |= hpd_bxt[intel_encoder->hpd_pin];
+	}
+
+	/* Mask all HPD control bits */
+	hotplug_ctrl = I915_READ(BXT_HOTPLUG_CTL) & ~BXT_HOTPLUG_CTL_MASK;
+
+	/* Enable requested port in hotplug control */
+	/* TODO: implement (short) HPD support on port A */
+	WARN_ON_ONCE(hotplug_port & BXT_DE_PORT_HP_DDIA);
+	if (hotplug_port & BXT_DE_PORT_HP_DDIB)
+		hotplug_ctrl |= BXT_DDIB_HPD_ENABLE;
+	if (hotplug_port & BXT_DE_PORT_HP_DDIC)
+		hotplug_ctrl |= BXT_DDIC_HPD_ENABLE;
+	I915_WRITE(BXT_HOTPLUG_CTL, hotplug_ctrl);
+
+	/* Unmask DDI hotplug in IMR */
+	hotplug_ctrl = I915_READ(GEN8_DE_PORT_IMR) & ~hotplug_port;
+	I915_WRITE(GEN8_DE_PORT_IMR, hotplug_ctrl);
+
+	/* Enable DDI hotplug in IER */
+	hotplug_ctrl = I915_READ(GEN8_DE_PORT_IER) | hotplug_port;
+	I915_WRITE(GEN8_DE_PORT_IER, hotplug_ctrl);
+	POSTING_READ(GEN8_DE_PORT_IER);
+}
+
 static void ibx_irq_postinstall(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -4279,7 +4321,10 @@ void intel_irq_init(struct drm_i915_private *dev_priv)
 		dev->driver->irq_uninstall = gen8_irq_uninstall;
 		dev->driver->enable_vblank = gen8_enable_vblank;
 		dev->driver->disable_vblank = gen8_disable_vblank;
+		if (HAS_PCH_SPLIT(dev))
 			dev_priv->display.hpd_irq_setup = ibx_hpd_irq_setup;
+		else
+			dev_priv->display.hpd_irq_setup = bxt_hpd_irq_setup;
 	} else if (HAS_PCH_SPLIT(dev)) {
 		dev->driver->irq_handler = ironlake_irq_handler;
 		dev->driver->irq_preinstall = ironlake_irq_reset;

drivers/gpu/drm/i915/i915_reg.h

@@ -5373,10 +5373,16 @@ enum skl_disp_power_wells {
 #define GEN8_DE_PORT_IMR 0x44444
 #define GEN8_DE_PORT_IIR 0x44448
 #define GEN8_DE_PORT_IER 0x4444c
-#define  GEN8_PORT_DP_A_HOTPLUG		(1 << 3)
 #define  GEN9_AUX_CHANNEL_D		(1 << 27)
 #define  GEN9_AUX_CHANNEL_C		(1 << 26)
 #define  GEN9_AUX_CHANNEL_B		(1 << 25)
+#define  BXT_DE_PORT_HP_DDIC		(1 << 5)
+#define  BXT_DE_PORT_HP_DDIB		(1 << 4)
+#define  BXT_DE_PORT_HP_DDIA		(1 << 3)
+#define  BXT_DE_PORT_HOTPLUG_MASK	(BXT_DE_PORT_HP_DDIA | \
+					 BXT_DE_PORT_HP_DDIB | \
+					 BXT_DE_PORT_HP_DDIC)
+#define  GEN8_PORT_DP_A_HOTPLUG		(1 << 3)
 #define  GEN8_AUX_CHANNEL_A		(1 << 0)
 
 #define GEN8_DE_MISC_ISR 0x44460
@@ -5390,6 +5396,21 @@ enum skl_disp_power_wells {
 #define GEN8_PCU_IIR 0x444e8
 #define GEN8_PCU_IER 0x444ec
 
+/* BXT hotplug control */
+#define BXT_HOTPLUG_CTL			0xC4030
+#define   BXT_DDIA_HPD_ENABLE		(1 << 28)
+#define   BXT_DDIA_HPD_STATUS		(3 << 24)
+#define   BXT_DDIC_HPD_ENABLE		(1 << 12)
+#define   BXT_DDIC_HPD_STATUS		(3 << 8)
+#define   BXT_DDIB_HPD_ENABLE		(1 << 4)
+#define   BXT_DDIB_HPD_STATUS		(3 << 0)
+#define   BXT_HOTPLUG_CTL_MASK		(BXT_DDIA_HPD_ENABLE | \
+					 BXT_DDIB_HPD_ENABLE | \
+					 BXT_DDIC_HPD_ENABLE)
+#define   BXT_HPD_STATUS_MASK		(BXT_DDIA_HPD_STATUS | \
+					 BXT_DDIB_HPD_STATUS | \
+					 BXT_DDIC_HPD_STATUS)
+
 #define ILK_DISPLAY_CHICKEN2	0x42004
 /* Required on all Ironlake and Sandybridge according to the B-Spec. */
 #define  ILK_ELPIN_409_SELECT	(1 << 25)