[PATCH v3 2/2] drm/i915/uapi: Add query for hwconfig table

[John.C.Harrison@xxxxxxxxx]

From: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>

GuC contains a consolidated table with a bunch of information about the
current device.

Previously, this information was spread and hardcoded to all the components
including GuC, i915 and various UMDs. The goal here is to consolidate
the data into GuC in a way that all interested components can grab the
very latest and synchronized information using a simple query.

As per most of the other queries, this one can be called twice.
Once with item.length=0 to determine the exact buffer size, then
allocate the user memory and call it again for to retrieve the
table data. For example:
  struct drm_i915_query_item item = {
    .query_id = DRM_I915_QUERY_HWCONCFIG_TABLE;
  };
  query.items_ptr = (int64_t) &item;
  query.num_items = 1;

  ioctl(fd, DRM_IOCTL_I915_QUERY, query, sizeof(query));

  if (item.length <= 0)
    return -ENOENT;

  data = malloc(item.length);
  item.data_ptr = (int64_t) &data;
  ioctl(fd, DRM_IOCTL_I915_QUERY, query, sizeof(query));

  // Parse the data as appropriate...

The returned array is a simple and flexible KLV (Key/Length/Value)
formatted table. For example, it could be just:
  enum device_attr {
     ATTR_SOME_VALUE = 0,
     ATTR_SOME_MASK  = 1,
  };

  static const u32 hwconfig[] = {
      ATTR_SOME_VALUE,
      1,             // Value Length in DWords
      8,             // Value

      ATTR_SOME_MASK,
      3,
      0x00FFFFFFFF, 0xFFFFFFFF, 0xFF000000,
  };

The attribute ids are defined in a hardware spec.

Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx>
Cc: Kenneth Graunke <kenneth.w.graunke@xxxxxxxxx>
Cc: Michal Wajdeczko <michal.wajdeczko@xxxxxxxxx>
Cc: Slawomir Milczarek <slawomir.milczarek@xxxxxxxxx>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Signed-off-by: John Harrison <John.C.Harrison@xxxxxxxxx>
Reviewed-by: Matthew Brost <matthew.brost@xxxxxxxxx>
---
 drivers/gpu/drm/i915/i915_query.c | 23 +++++++++++++++++++++++
 include/uapi/drm/i915_drm.h       |  1 +
 2 files changed, 24 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_query.c b/drivers/gpu/drm/i915/i915_query.c
index 2dfbc22857a3..609e64d5f395 100644
--- a/drivers/gpu/drm/i915/i915_query.c
+++ b/drivers/gpu/drm/i915/i915_query.c
@@ -479,12 +479,35 @@ static int query_memregion_info(struct drm_i915_private *i915,
 	return total_length;
 }
 
+static int query_hwconfig_table(struct drm_i915_private *i915,
+				struct drm_i915_query_item *query_item)
+{
+	struct intel_gt *gt = to_gt(i915);
+	struct intel_guc_hwconfig *hwconfig = &gt->uc.guc.hwconfig;
+
+	if (!hwconfig->size || !hwconfig->ptr)
+		return -ENODEV;
+
+	if (query_item->length == 0)
+		return hwconfig->size;
+
+	if (query_item->length < hwconfig->size)
+		return -EINVAL;
+
+	if (copy_to_user(u64_to_user_ptr(query_item->data_ptr),
+			 hwconfig->ptr, hwconfig->size))
+		return -EFAULT;
+
+	return hwconfig->size;
+}
+
 static int (* const i915_query_funcs[])(struct drm_i915_private *dev_priv,
 					struct drm_i915_query_item *query_item) = {
 	query_topology_info,
 	query_engine_info,
 	query_perf_config,
 	query_memregion_info,
+	query_hwconfig_table,
 };
 
 int i915_query_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 914ebd9290e5..132515199f27 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -2685,6 +2685,7 @@ struct drm_i915_query_item {
 #define DRM_I915_QUERY_ENGINE_INFO	2
 #define DRM_I915_QUERY_PERF_CONFIG      3
 #define DRM_I915_QUERY_MEMORY_REGIONS   4
+#define DRM_I915_QUERY_HWCONFIG_TABLE   5
 /* Must be kept compact -- no holes and well documented */
 
 	/**
-- 
2.25.1