drm/i915: Enable GuC firmware log

Allocate a GEM object to hold GuC log data. A debugfs interface
(i915_guc_log_dump) is provided to print out the log content.

v2:
    Add struct members at point of use [Chris Wilson]

v6:
    Rebased

Issue: VIZ-4884
Signed-off-by: Alex Dai <yu.dai@intel.com>
Signed-off-by: Dave Gordon <david.s.gordon@intel.com>
Reviewed-by: Tom O'Rourke <Tom.O'Rourke@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -2412,6 +2412,34 @@ static int i915_guc_load_status_info(struct seq_file *m, void *data)
 	return 0;
 }
 
+static int i915_guc_log_dump(struct seq_file *m, void *data)
+{
+	struct drm_info_node *node = m->private;
+	struct drm_device *dev = node->minor->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct drm_i915_gem_object *log_obj = dev_priv->guc.log_obj;
+	u32 *log;
+	int i = 0, pg;
+
+	if (!log_obj)
+		return 0;
+
+	for (pg = 0; pg < log_obj->base.size / PAGE_SIZE; pg++) {
+		log = kmap_atomic(i915_gem_object_get_page(log_obj, pg));
+
+		for (i = 0; i < PAGE_SIZE / sizeof(u32); i += 4)
+			seq_printf(m, "0x%08x 0x%08x 0x%08x 0x%08x\n",
+				   *(log + i), *(log + i + 1),
+				   *(log + i + 2), *(log + i + 3));
+
+		kunmap_atomic(log);
+	}
+
+	seq_putc(m, '\n');
+
+	return 0;
+}
+
 static int i915_edp_psr_status(struct seq_file *m, void *data)
 {
 	struct drm_info_node *node = m->private;
@@ -5072,6 +5100,7 @@ static const struct drm_info_list i915_debugfs_list[] = {
 	{"i915_gem_hws_vebox", i915_hws_info, 0, (void *)VECS},
 	{"i915_gem_batch_pool", i915_gem_batch_pool_info, 0},
 	{"i915_guc_load_status", i915_guc_load_status_info, 0},
+	{"i915_guc_log_dump", i915_guc_log_dump, 0},
 	{"i915_frequency_info", i915_frequency_info, 0},
 	{"i915_hangcheck_info", i915_hangcheck_info, 0},
 	{"i915_drpc_info", i915_drpc_info, 0},

drivers/gpu/drm/i915/i915_guc_submission.c

@@ -79,6 +79,47 @@ static void gem_release_guc_obj(struct drm_i915_gem_object *obj)
 	drm_gem_object_unreference(&obj->base);
 }
 
+static void guc_create_log(struct intel_guc *guc)
+{
+	struct drm_i915_private *dev_priv = guc_to_i915(guc);
+	struct drm_i915_gem_object *obj;
+	unsigned long offset;
+	uint32_t size, flags;
+
+	if (i915.guc_log_level < GUC_LOG_VERBOSITY_MIN)
+		return;
+
+	if (i915.guc_log_level > GUC_LOG_VERBOSITY_MAX)
+		i915.guc_log_level = GUC_LOG_VERBOSITY_MAX;
+
+	/* The first page is to save log buffer state. Allocate one
+	 * extra page for others in case for overlap */
+	size = (1 + GUC_LOG_DPC_PAGES + 1 +
+		GUC_LOG_ISR_PAGES + 1 +
+		GUC_LOG_CRASH_PAGES + 1) << PAGE_SHIFT;
+
+	obj = guc->log_obj;
+	if (!obj) {
+		obj = gem_allocate_guc_obj(dev_priv->dev, size);
+		if (!obj) {
+			/* logging will be off */
+			i915.guc_log_level = -1;
+			return;
+		}
+
+		guc->log_obj = obj;
+	}
+
+	/* each allocated unit is a page */
+	flags = GUC_LOG_VALID | GUC_LOG_NOTIFY_ON_HALF_FULL |
+		(GUC_LOG_DPC_PAGES << GUC_LOG_DPC_SHIFT) |
+		(GUC_LOG_ISR_PAGES << GUC_LOG_ISR_SHIFT) |
+		(GUC_LOG_CRASH_PAGES << GUC_LOG_CRASH_SHIFT);
+
+	offset = i915_gem_obj_ggtt_offset(obj) >> PAGE_SHIFT; /* in pages */
+	guc->log_flags = (offset << GUC_LOG_BUF_ADDR_SHIFT) | flags;
+}
+
 /*
  * Set up the memory resources to be shared with the GuC.  At this point,
  * we require just one object that can be mapped through the GGTT.
@@ -103,6 +144,8 @@ int i915_guc_submission_init(struct drm_device *dev)
 
 	ida_init(&guc->ctx_ids);
 
+	guc_create_log(guc);
+
 	return 0;
 }
 
@@ -111,6 +154,9 @@ void i915_guc_submission_fini(struct drm_device *dev)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_guc *guc = &dev_priv->guc;
 
+	gem_release_guc_obj(dev_priv->guc.log_obj);
+	guc->log_obj = NULL;
+
 	if (guc->ctx_pool_obj)
 		ida_destroy(&guc->ctx_ids);
 	gem_release_guc_obj(guc->ctx_pool_obj);

drivers/gpu/drm/i915/intel_guc.h

@@ -56,6 +56,7 @@ struct intel_guc {
 	struct intel_guc_fw guc_fw;
 
 	uint32_t log_flags;
+	struct drm_i915_gem_object *log_obj;
 
 	struct drm_i915_gem_object *ctx_pool_obj;
 	struct ida ctx_ids;