drm/displayid: add separate drm_displayid.c

We'll be adding more DisplayID specific functions going forward, so
start off by splitting out a few functions to a separate file.

We don't bother with exporting the functions; at least for now they
should be needed solely within drm.ko.

No functional changes.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/07942d5011891b8e8f77245c78b34f4af97a9315.1617024940.git.jani.nikula@intel.com

drivers/gpu/drm/Makefile

@@ -7,7 +7,7 @@ drm-y       :=	drm_auth.o drm_cache.o \
 		drm_file.o drm_gem.o drm_ioctl.o drm_irq.o \
 		drm_drv.o \
 		drm_sysfs.o drm_hashtab.o drm_mm.o \
-		drm_crtc.o drm_fourcc.o drm_modes.o drm_edid.o \
+		drm_crtc.o drm_fourcc.o drm_modes.o drm_edid.o drm_displayid.o \
 		drm_encoder_slave.o \
 		drm_trace_points.o drm_prime.o \
 		drm_rect.o drm_vma_manager.o drm_flip_work.o \

drivers/gpu/drm/drm_displayid.c

@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2021 Intel Corporation
+ */
+
+#include <drm/drm_displayid.h>
+#include <drm/drm_edid.h>
+#include <drm/drm_print.h>
+
+static int validate_displayid(const u8 *displayid, int length, int idx)
+{
+	int i, dispid_length;
+	u8 csum = 0;
+	const struct displayid_hdr *base;
+
+	base = (const struct displayid_hdr *)&displayid[idx];
+
+	DRM_DEBUG_KMS("base revision 0x%x, length %d, %d %d\n",
+		      base->rev, base->bytes, base->prod_id, base->ext_count);
+
+	/* +1 for DispID checksum */
+	dispid_length = sizeof(*base) + base->bytes + 1;
+	if (dispid_length > length - idx)
+		return -EINVAL;
+
+	for (i = 0; i < dispid_length; i++)
+		csum += displayid[idx + i];
+	if (csum) {
+		DRM_NOTE("DisplayID checksum invalid, remainder is %d\n", csum);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+const u8 *drm_find_displayid_extension(const struct edid *edid,
+				       int *length, int *idx,
+				       int *ext_index)
+{
+	const u8 *displayid = drm_find_edid_extension(edid, DISPLAYID_EXT, ext_index);
+	const struct displayid_hdr *base;
+	int ret;
+
+	if (!displayid)
+		return NULL;
+
+	/* EDID extensions block checksum isn't for us */
+	*length = EDID_LENGTH - 1;
+	*idx = 1;
+
+	ret = validate_displayid(displayid, *length, *idx);
+	if (ret)
+		return NULL;
+
+	base = (const struct displayid_hdr *)&displayid[*idx];
+	*length = *idx + sizeof(*base) + base->bytes;
+
+	return displayid;
+}

drivers/gpu/drm/drm_edid.c

@@ -1585,8 +1585,6 @@ module_param_named(edid_fixup, edid_fixup, int, 0400);
 MODULE_PARM_DESC(edid_fixup,
 		 "Minimum number of valid EDID header bytes (0-8, default 6)");
 
-static int validate_displayid(const u8 *displayid, int length, int idx);
-
 static int drm_edid_block_checksum(const u8 *raw_edid)
 {
 	int i;
@@ -3241,8 +3239,8 @@ add_detailed_modes(struct drm_connector *connector, struct edid *edid,
 /*
  * Search EDID for CEA extension block.
  */
-static const u8 *drm_find_edid_extension(const struct edid *edid,
+const u8 *drm_find_edid_extension(const struct edid *edid,
-					 int ext_id, int *ext_index)
+				  int ext_id, int *ext_index)
 {
 	const u8 *edid_ext = NULL;
 	int i;
@@ -3266,32 +3264,6 @@ static const u8 *drm_find_edid_extension(const struct edid *edid,
 	return edid_ext;
 }
 
-
-static const u8 *drm_find_displayid_extension(const struct edid *edid,
-					      int *length, int *idx,
-					      int *ext_index)
-{
-	const u8 *displayid = drm_find_edid_extension(edid, DISPLAYID_EXT, ext_index);
-	const struct displayid_hdr *base;
-	int ret;
-
-	if (!displayid)
-		return NULL;
-
-	/* EDID extensions block checksum isn't for us */
-	*length = EDID_LENGTH - 1;
-	*idx = 1;
-
-	ret = validate_displayid(displayid, *length, *idx);
-	if (ret)
-		return NULL;
-
-	base = (const struct displayid_hdr *)&displayid[*idx];
-	*length = *idx + sizeof(*base) + base->bytes;
-
-	return displayid;
-}
-
 static const u8 *drm_find_cea_extension(const struct edid *edid)
 {
 	int length, idx;
@@ -5287,32 +5259,6 @@ u32 drm_add_display_info(struct drm_connector *connector, const struct edid *edi
 	return quirks;
 }
 
-static int validate_displayid(const u8 *displayid, int length, int idx)
-{
-	int i, dispid_length;
-	u8 csum = 0;
-	const struct displayid_hdr *base;
-
-	base = (const struct displayid_hdr *)&displayid[idx];
-
-	DRM_DEBUG_KMS("base revision 0x%x, length %d, %d %d\n",
-		      base->rev, base->bytes, base->prod_id, base->ext_count);
-
-	/* +1 for DispID checksum */
-	dispid_length = sizeof(*base) + base->bytes + 1;
-	if (dispid_length > length - idx)
-		return -EINVAL;
-
-	for (i = 0; i < dispid_length; i++)
-		csum += displayid[idx + i];
-	if (csum) {
-		DRM_NOTE("DisplayID checksum invalid, remainder is %d\n", csum);
-		return -EINVAL;
-	}
-
-	return 0;
-}
-
 static struct drm_display_mode *drm_mode_displayid_detailed(struct drm_device *dev,
 							    struct displayid_detailed_timings_1 *timings)
 {

include/drm/drm_displayid.h

@@ -22,6 +22,10 @@
 #ifndef DRM_DISPLAYID_H
 #define DRM_DISPLAYID_H
 
+#include <linux/types.h>
+
+struct edid;
+
 #define DATA_BLOCK_PRODUCT_ID 0x00
 #define DATA_BLOCK_DISPLAY_PARAMETERS 0x01
 #define DATA_BLOCK_COLOR_CHARACTERISTICS 0x02
@@ -100,4 +104,8 @@ struct displayid_detailed_timing_block {
 	     (idx) += sizeof(struct displayid_block) + (block)->num_bytes, \
 	     (block) = (const struct displayid_block *)&(displayid)[idx])
 
+const u8 *drm_find_displayid_extension(const struct edid *edid,
+				       int *length, int *idx,
+				       int *ext_index);
+
 #endif

include/drm/drm_edid.h

@@ -543,5 +543,8 @@ struct drm_display_mode *drm_mode_find_dmt(struct drm_device *dev,
 struct drm_display_mode *
 drm_display_mode_from_cea_vic(struct drm_device *dev,
 			      u8 video_code);
+const u8 *drm_find_edid_extension(const struct edid *edid,
+				  int ext_id, int *ext_index);
+
 
 #endif /* __DRM_EDID_H__ */