drm/xe: Add debugfs to dump GuC's hwconfig

Although the query uapi is the official way to get at the GuC's hwconfig
table contents, it's still useful to have a quick debugfs interface to
dump the table in a human-readable format while debugging the driver.
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Reviewed-by: Jagmeet Randhawa <jagmeet.randhawa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240815172602.2729146-3-matthew.d.roper@intel.com

drivers/gpu/drm/xe/xe_gt_debugfs.c

@@ -19,6 +19,7 @@
 #include "xe_gt_sriov_vf_debugfs.h"
 #include "xe_gt_stats.h"
 #include "xe_gt_topology.h"
+#include "xe_guc_hwconfig.h"
 #include "xe_hw_engine.h"
 #include "xe_lrc.h"
 #include "xe_macros.h"
@@ -270,6 +271,15 @@ static int vecs_default_lrc(struct xe_gt *gt, struct drm_printer *p)
 	return 0;
 }
 
+static int hwconfig(struct xe_gt *gt, struct drm_printer *p)
+{
+	xe_pm_runtime_get(gt_to_xe(gt));
+	xe_guc_hwconfig_dump(&gt->uc.guc, p);
+	xe_pm_runtime_put(gt_to_xe(gt));
+
+	return 0;
+}
+
 static const struct drm_info_list debugfs_list[] = {
 	{"hw_engines", .show = xe_gt_debugfs_simple_show, .data = hw_engines},
 	{"force_reset", .show = xe_gt_debugfs_simple_show, .data = force_reset},
@@ -288,6 +298,7 @@ static const struct drm_info_list debugfs_list[] = {
 	{"default_lrc_vcs", .show = xe_gt_debugfs_simple_show, .data = vcs_default_lrc},
 	{"default_lrc_vecs", .show = xe_gt_debugfs_simple_show, .data = vecs_default_lrc},
 	{"stats", .show = xe_gt_debugfs_simple_show, .data = xe_gt_stats_print_info},
+	{"hwconfig", .show = xe_gt_debugfs_simple_show, .data = hwconfig},
 };
 
 void xe_gt_debugfs_register(struct xe_gt *gt)

drivers/gpu/drm/xe/xe_guc_hwconfig.c

@@ -6,6 +6,7 @@
 #include "xe_guc_hwconfig.h"
 
 #include <drm/drm_managed.h>
+#include <drm/drm_print.h>
 
 #include "abi/guc_actions_abi.h"
 #include "xe_bo.h"
@@ -103,3 +104,59 @@ void xe_guc_hwconfig_copy(struct xe_guc *guc, void *dst)
 	xe_map_memcpy_from(xe, dst, &guc->hwconfig.bo->vmap, 0,
 			   guc->hwconfig.size);
 }
+
+void xe_guc_hwconfig_dump(struct xe_guc *guc, struct drm_printer *p)
+{
+	size_t size = xe_guc_hwconfig_size(guc);
+	u32 *hwconfig;
+	u64 num_dw;
+	u32 extra_bytes;
+	int i = 0;
+
+	if (size == 0) {
+		drm_printf(p, "No hwconfig available\n");
+		return;
+	}
+
+	num_dw = div_u64_rem(size, sizeof(u32), &extra_bytes);
+
+	hwconfig = kzalloc(size, GFP_KERNEL);
+	if (!hwconfig) {
+		drm_printf(p, "Error: could not allocate hwconfig memory\n");
+		return;
+	}
+
+	xe_guc_hwconfig_copy(guc, hwconfig);
+
+	/* An entry requires at least three dwords for key, length, value */
+	while (i + 3 <= num_dw) {
+		u32 attribute = hwconfig[i++];
+		u32 len_dw = hwconfig[i++];
+
+		if (i + len_dw > num_dw) {
+			drm_printf(p, "Error: Attribute %u is %u dwords, but only %llu remain\n",
+				   attribute, len_dw, num_dw - i);
+			len_dw = num_dw - i;
+		}
+
+		/*
+		 * If it's a single dword (as most hwconfig attributes are),
+		 * then it's probably a number that makes sense to display
+		 * in decimal form.  In the rare cases where it's more than
+		 * one dword, just print it in hex form and let the user
+		 * figure out how to interpret it.
+		 */
+		if (len_dw == 1)
+			drm_printf(p, "[%2u] = %u\n", attribute, hwconfig[i]);
+		else
+			drm_printf(p, "[%2u] = { %*ph }\n", attribute,
+				   (int)(len_dw * sizeof(u32)), &hwconfig[i]);
+		i += len_dw;
+	}
+
+	if (i < num_dw || extra_bytes)
+		drm_printf(p, "Error: %llu extra bytes at end of hwconfig\n",
+			   (num_dw - i) * sizeof(u32) + extra_bytes);
+
+	kfree(hwconfig);
+}

drivers/gpu/drm/xe/xe_guc_hwconfig.h

@@ -8,10 +8,12 @@
 
 #include <linux/types.h>
 
+struct drm_printer;
 struct xe_guc;
 
 int xe_guc_hwconfig_init(struct xe_guc *guc);
 u32 xe_guc_hwconfig_size(struct xe_guc *guc);
 void xe_guc_hwconfig_copy(struct xe_guc *guc, void *dst);
+void xe_guc_hwconfig_dump(struct xe_guc *guc, struct drm_printer *p);
 
 #endif