drm/xe/xe2: Determine bios enablement for flat ccs on igfx

If bios disables flat ccs on igfx make has_flat_ccs as 0 and notify
via drm_dbg.

Bspec:59255

v2:
 - Release forcewake.
 - Add registers in order.
 - drop dgfx condition and only add it back in the future
when the support for an Xe2 dgpu will be added.
- Use drm_dbg instead of drm_info. (Matt)

v3:
 - Address nit(Matt)

Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Acked-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/regs/xe_gt_regs.h

@@ -162,6 +162,9 @@
 #define XEHP_SQCM				XE_REG_MCR(0x8724)
 #define   EN_32B_ACCESS				REG_BIT(30)
 
+#define XE2_FLAT_CCS_BASE_RANGE_LOWER		XE_REG_MCR(0x8800)
+#define   XE2_FLAT_CCS_ENABLE			REG_BIT(0)
+
 #define GSCPSMI_BASE				XE_REG(0x880c)
 
 #define	MIRROR_FUSE3				XE_REG(0x9118)

drivers/gpu/drm/xe/xe_device.c

@@ -15,6 +15,7 @@
 #include <drm/drm_print.h>
 #include <drm/xe_drm.h>
 
+#include "regs/xe_gt_regs.h"
 #include "regs/xe_regs.h"
 #include "xe_bo.h"
 #include "xe_debugfs.h"
@@ -26,6 +27,7 @@
 #include "xe_exec.h"
 #include "xe_ggtt.h"
 #include "xe_gt.h"
+#include "xe_gt_mcr.h"
 #include "xe_irq.h"
 #include "xe_mmio.h"
 #include "xe_module.h"
@@ -401,6 +403,30 @@ int xe_device_probe_early(struct xe_device *xe)
 	return 0;
 }
 
+static int xe_device_set_has_flat_ccs(struct  xe_device *xe)
+{
+	u32 reg;
+	int err;
+
+	if (GRAPHICS_VER(xe) < 20 || !xe->info.has_flat_ccs)
+		return 0;
+
+	struct xe_gt *gt = xe_root_mmio_gt(xe);
+
+	err = xe_force_wake_get(gt_to_fw(gt), XE_FW_GT);
+	if (err)
+		return err;
+
+	reg = xe_gt_mcr_unicast_read_any(gt, XE2_FLAT_CCS_BASE_RANGE_LOWER);
+	xe->info.has_flat_ccs = (reg & XE2_FLAT_CCS_ENABLE);
+
+	if (!xe->info.has_flat_ccs)
+		drm_dbg(&xe->drm,
+			"Flat CCS has been disabled in bios, May lead to performance impact");
+
+	return xe_force_wake_put(gt_to_fw(gt), XE_FW_GT);
+}
+
 int xe_device_probe(struct xe_device *xe)
 {
 	struct xe_tile *tile;
@@ -456,6 +482,10 @@ int xe_device_probe(struct xe_device *xe)
 			goto err_irq_shutdown;
 	}
 
+	err = xe_device_set_has_flat_ccs(xe);
+	if (err)
+		return err;
+
 	err = xe_mmio_probe_vram(xe);
 	if (err)
 		goto err_irq_shutdown;