1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3   drm_edid_load.c: use a built-in EDID data set or load it via the firmware
  4		    interface
  5
  6   Copyright (C) 2012 Carsten Emde <C.Emde@osadl.org>
  7
  8*/
  9
 10#include <linux/firmware.h>
 11#include <linux/module.h>
 12#include <linux/platform_device.h>
 13
 14#include <drm/drm_connector.h>
 15#include <drm/drm_drv.h>
 16#include <drm/drm_edid.h>
 17#include <drm/drm_print.h>
 18
 19#include "drm_crtc_internal.h"
 20
 21static char edid_firmware[PATH_MAX];
 22module_param_string(edid_firmware, edid_firmware, sizeof(edid_firmware), 0644);
 23MODULE_PARM_DESC(edid_firmware,
 24		 "Do not probe monitor, use specified EDID blob from /lib/firmware instead.");
 25
 26static const struct drm_edid *edid_load(struct drm_connector *connector, const char *name)
 27{
 28	const struct firmware *fw = NULL;
 29	const struct drm_edid *drm_edid;
 30	int err;
 31
 32	err = request_firmware(&fw, name, connector->dev->dev);
 33	if (err) {
 34		drm_err(connector->dev,
 35			"[CONNECTOR:%d:%s] Requesting EDID firmware \"%s\" failed (err=%d)\n",
 36			connector->base.id, connector->name,
 37			name, err);
 38		return ERR_PTR(err);
 39	}
 40
 41	drm_dbg_kms(connector->dev, "[CONNECTOR:%d:%s] Loaded external firmware EDID \"%s\"\n",
 42		    connector->base.id, connector->name, name);
 43
 44	drm_edid = drm_edid_alloc(fw->data, fw->size);
 45	if (!drm_edid_valid(drm_edid)) {
 46		drm_err(connector->dev, "Invalid firmware EDID \"%s\"\n", name);
 47		drm_edid_free(drm_edid);
 48		drm_edid = ERR_PTR(-EINVAL);
 49	}
 50
 51	release_firmware(fw);
 52
 53	return drm_edid;
 54}
 55
 56const struct drm_edid *drm_edid_load_firmware(struct drm_connector *connector)
 57{
 58	char *edidname, *last, *colon, *fwstr, *edidstr, *fallback = NULL;
 59	const struct drm_edid *drm_edid;
 60
 61	if (edid_firmware[0] == '\0')
 62		return ERR_PTR(-ENOENT);
 63
 64	/*
 65	 * If there are multiple edid files specified and separated
 66	 * by commas, search through the list looking for one that
 67	 * matches the connector.
 68	 *
 69	 * If there's one or more that doesn't specify a connector, keep
 70	 * the last one found one as a fallback.
 71	 */
 72	fwstr = kstrdup(edid_firmware, GFP_KERNEL);
 73	if (!fwstr)
 74		return ERR_PTR(-ENOMEM);
 75	edidstr = fwstr;
 76
 77	while ((edidname = strsep(&edidstr, ","))) {
 78		colon = strchr(edidname, ':');
 79		if (colon != NULL) {
 80			if (strncmp(connector->name, edidname, colon - edidname))
 81				continue;
 82			edidname = colon + 1;
 83			break;
 84		}
 85
 86		if (*edidname != '\0') /* corner case: multiple ',' */
 87			fallback = edidname;
 88	}
 89
 90	if (!edidname) {
 91		if (!fallback) {
 92			kfree(fwstr);
 93			return ERR_PTR(-ENOENT);
 94		}
 95		edidname = fallback;
 96	}
 97
 98	last = edidname + strlen(edidname) - 1;
 99	if (*last == '\n')
100		*last = '\0';
101
102	drm_edid = edid_load(connector, edidname);
103
104	kfree(fwstr);
105
106	return drm_edid;
107}