drm/i915/mtl/gsc: Add a gsc_info debugfs

Add a new debugfs to dump information about the GSC. This includes:

- the FW path and SW tracking status;
- the release, security and compatibility versions;
- the HECI1 status registers.

Note that those are the same registers that the mei driver dumps in
their own status sysfs on DG2 (where mei owns the GSC).

To make it simpler to loop through the status register, the code has
been update to use a PICK macro and the existing code using the regs had
been adapted to match.

v2: fix includes and copyright dates (Alan)
v3: actually fix the includes

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Alan Previn <alan.previn.teres.alexis@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Alan Previn <alan.previn.teres.alexis@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230612181529.2222451-5-daniele.ceraolospurio@intel.com
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index e0fc0f5..05c51a2 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -941,8 +941,30 @@
 #define HECI_H_GS1(base)	_MMIO((base) + 0xc4c)
 #define   HECI_H_GS1_ER_PREP	REG_BIT(0)
 
-#define HECI_FWSTS5(base)		_MMIO((base) + 0xc68)
-#define   HECI_FWSTS5_HUC_AUTH_DONE	(1 << 19)
+/*
+ * The FWSTS register values are FW defined and can be different between
+ * HECI1 and HECI2
+ */
+#define HECI_FWSTS1				0xc40
+#define   HECI1_FWSTS1_CURRENT_STATE			REG_GENMASK(3, 0)
+#define   HECI1_FWSTS1_CURRENT_STATE_RESET		0
+#define   HECI1_FWSTS1_PROXY_STATE_NORMAL		5
+#define   HECI1_FWSTS1_INIT_COMPLETE			REG_BIT(9)
+#define HECI_FWSTS2				0xc48
+#define HECI_FWSTS3				0xc60
+#define HECI_FWSTS4				0xc64
+#define HECI_FWSTS5				0xc68
+#define   HECI1_FWSTS5_HUC_AUTH_DONE	(1 << 19)
+#define HECI_FWSTS6				0xc6c
+
+/* the FWSTS regs are 1-based, so we use -base for index 0 to get an invalid reg */
+#define HECI_FWSTS(base, x) _MMIO((base) + _PICK(x, -(base), \
+						    HECI_FWSTS1, \
+						    HECI_FWSTS2, \
+						    HECI_FWSTS3, \
+						    HECI_FWSTS4, \
+						    HECI_FWSTS5, \
+						    HECI_FWSTS6))
 
 #define HSW_GTT_CACHE_EN	_MMIO(0x4024)
 #define   GTT_CACHE_EN_ALL	0xF0007FFF