drm/i915: Parse VBT data for lspcon

Many GEN9 boards come with on-board lspcon cards.
Fot these boards, VBT configuration should properly point out
if a particular port contains lspcon device, so that driver can
initialize it properly.

This patch adds a utility function, which checks the VBT flag
for lspcon bit, and tells us if a port is configured to have a
lspcon device or not.

V2: Fixed review comments from Ville
- Do not forget PORT_D while checking lspcon for GEN9

V3: Addressed review comments from Rodrigo
- Create a HAS_LSPCON() macro for better use case handling.
- Do not dump warnings for non-gen-9 platforms, it will be noise.

V4: Rebase
V5: Rebase
V6: Pass dev_priv to HAS_LSPCON() macro

Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Acked-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1476455212-27893-4-git-send-email-shashank.sharma@intel.com

drivers/gpu/drm/i915/i915_drv.h

@@ -2862,6 +2862,8 @@ struct drm_i915_cmd_table {
 
 #define HAS_GMCH_DISPLAY(dev_priv) ((dev_priv)->info.has_gmch_display)
 
+#define HAS_LSPCON(dev_priv) (IS_GEN9(dev_priv))
+
 /* DPF == dynamic parity feature */
 #define HAS_L3_DPF(dev_priv) ((dev_priv)->info.has_l3_dpf)
 #define NUM_L3_SLICES(dev_priv) (IS_HSW_GT3(dev_priv) ? \
@@ -3629,6 +3631,9 @@ bool intel_bios_is_port_dp_dual_mode(struct drm_i915_private *dev_priv, enum por
 bool intel_bios_is_dsi_present(struct drm_i915_private *dev_priv, enum port *port);
 bool intel_bios_is_port_hpd_inverted(struct drm_i915_private *dev_priv,
 				     enum port port);
+bool intel_bios_is_lspcon_present(struct drm_i915_private *dev_priv,
+				enum port port);
+
 
 /* intel_opregion.c */
 #ifdef CONFIG_ACPI

drivers/gpu/drm/i915/intel_bios.c

@@ -1763,3 +1763,52 @@ intel_bios_is_port_hpd_inverted(struct drm_i915_private *dev_priv,
 
 	return false;
 }
+
+/**
+ * intel_bios_is_lspcon_present - if LSPCON is attached on %port
+ * @dev_priv:	i915 device instance
+ * @port:	port to check
+ *
+ * Return true if LSPCON is present on this port
+ */
+bool
+intel_bios_is_lspcon_present(struct drm_i915_private *dev_priv,
+				enum port port)
+{
+	int i;
+
+	if (!HAS_LSPCON(dev_priv))
+		return false;
+
+	for (i = 0; i < dev_priv->vbt.child_dev_num; i++) {
+		if (!dev_priv->vbt.child_dev[i].common.lspcon)
+			continue;
+
+		switch (dev_priv->vbt.child_dev[i].common.dvo_port) {
+		case DVO_PORT_DPA:
+		case DVO_PORT_HDMIA:
+			if (port == PORT_A)
+				return true;
+			break;
+		case DVO_PORT_DPB:
+		case DVO_PORT_HDMIB:
+			if (port == PORT_B)
+				return true;
+			break;
+		case DVO_PORT_DPC:
+		case DVO_PORT_HDMIC:
+			if (port == PORT_C)
+				return true;
+			break;
+		case DVO_PORT_DPD:
+		case DVO_PORT_HDMID:
+			if (port == PORT_D)
+				return true;
+			break;
+		default:
+			break;
+		}
+	}
+
+	return false;
+}