drm/i915/dg1: Add fake PCH

DG1 has the south engine display on the same PCI device. Ideally we
could use HAS_PCH_SPLIT(), but that macro is misused all across the
code base to rather signify a range of gens. So add a fake one for DG1
to be used where needed.

Cc: Aditya Swarup <aditya.swarup@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200713182321.12390-6-lucas.demarchi@intel.com

drivers/gpu/drm/i915/intel_pch.c

@@ -188,6 +188,12 @@ void intel_detect_pch(struct drm_i915_private *dev_priv)
 {
 	struct pci_dev *pch = NULL;
 
+	/* DG1 has south engine display on the same PCI device */
+	if (IS_DG1(dev_priv)) {
+		dev_priv->pch_type = PCH_DG1;
+		return;
+	}
+
 	/*
 	 * The reason to probe ISA bridge instead of Dev31:Fun0 is to
 	 * make graphics device passthrough work easy for VMM, that only

drivers/gpu/drm/i915/intel_pch.h

@@ -26,6 +26,9 @@ enum intel_pch {
 	PCH_JSP,	/* Jasper Lake PCH */
 	PCH_MCC,        /* Mule Creek Canyon PCH */
 	PCH_TGP,	/* Tiger Lake PCH */
+
+	/* Fake PCHs, functionality handled on the same PCI dev */
+	PCH_DG1 = 1024,
 };
 
 #define INTEL_PCH_DEVICE_ID_MASK		0xff80
@@ -56,6 +59,7 @@ enum intel_pch {
 
 #define INTEL_PCH_TYPE(dev_priv)		((dev_priv)->pch_type)
 #define INTEL_PCH_ID(dev_priv)			((dev_priv)->pch_id)
+#define HAS_PCH_DG1(dev_priv)			(INTEL_PCH_TYPE(dev_priv) == PCH_DG1)
 #define HAS_PCH_JSP(dev_priv)			(INTEL_PCH_TYPE(dev_priv) == PCH_JSP)
 #define HAS_PCH_MCC(dev_priv)			(INTEL_PCH_TYPE(dev_priv) == PCH_MCC)
 #define HAS_PCH_TGP(dev_priv)			(INTEL_PCH_TYPE(dev_priv) == PCH_TGP)