drm/edid: add #defines and helpers for ELD

In the interest of reducing magic numbers and having to cross check with
the specs all the time.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 102 insertions, 0 deletions

diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
index b96031d947a0..c2f1bfa22010 100644
--- a/include/drm/drm_edid.h
+++ b/include/drm/drm_edid.h
@@ -207,6 +207,61 @@ struct detailed_timing {
 #define DRM_EDID_HDMI_DC_30               (1 << 4)
 #define DRM_EDID_HDMI_DC_Y444             (1 << 3)
 
+/* ELD Header Block */
+#define DRM_ELD_HEADER_BLOCK_SIZE       4
+
+#define DRM_ELD_VER                     0
+# define DRM_ELD_VER_SHIFT              3
+# define DRM_ELD_VER_MASK               (0x1f << 3)
+
+#define DRM_ELD_BASELINE_ELD_LEN        2       /* in dwords! */
+
+/* ELD Baseline Block for ELD_Ver == 2 */
+#define DRM_ELD_CEA_EDID_VER_MNL        4
+# define DRM_ELD_CEA_EDID_VER_SHIFT     5
+# define DRM_ELD_CEA_EDID_VER_MASK      (7 << 5)
+# define DRM_ELD_CEA_EDID_VER_NONE      (0 << 5)
+# define DRM_ELD_CEA_EDID_VER_CEA861    (1 << 5)
+# define DRM_ELD_CEA_EDID_VER_CEA861A   (2 << 5)
+# define DRM_ELD_CEA_EDID_VER_CEA861BCD (3 << 5)
+# define DRM_ELD_MNL_SHIFT              0
+# define DRM_ELD_MNL_MASK               (0x1f << 0)
+
+#define DRM_ELD_SAD_COUNT_CONN_TYPE     5
+# define DRM_ELD_SAD_COUNT_SHIFT        4
+# define DRM_ELD_SAD_COUNT_MASK         (0xf << 4)
+# define DRM_ELD_CONN_TYPE_SHIFT        2
+# define DRM_ELD_CONN_TYPE_MASK         (3 << 2)
+# define DRM_ELD_CONN_TYPE_HDMI         (0 << 2)
+# define DRM_ELD_CONN_TYPE_DP           (1 << 2)
+# define DRM_ELD_SUPPORTS_AI            (1 << 1)
+# define DRM_ELD_SUPPORTS_HDCP          (1 << 0)
+
+#define DRM_ELD_AUD_SYNCH_DELAY         6       /* in units of 2 ms */
+# define DRM_ELD_AUD_SYNCH_DELAY_MAX    0xfa    /* 500 ms */
+
+#define DRM_ELD_SPEAKER                 7
+# define DRM_ELD_SPEAKER_RLRC           (1 << 6)
+# define DRM_ELD_SPEAKER_FLRC           (1 << 5)
+# define DRM_ELD_SPEAKER_RC             (1 << 4)
+# define DRM_ELD_SPEAKER_RLR            (1 << 3)
+# define DRM_ELD_SPEAKER_FC             (1 << 2)
+# define DRM_ELD_SPEAKER_LFE            (1 << 1)
+# define DRM_ELD_SPEAKER_FLR            (1 << 0)
+
+#define DRM_ELD_PORT_ID                 8       /* offsets 8..15 inclusive */
+# define DRM_ELD_PORT_ID_LEN            8
+
+#define DRM_ELD_MANUFACTURER_NAME0      16
+#define DRM_ELD_MANUFACTURER_NAME1      17
+
+#define DRM_ELD_PRODUCT_CODE0           18
+#define DRM_ELD_PRODUCT_CODE1           19
+
+#define DRM_ELD_MONITOR_NAME_STRING     20      /* offsets 20..(20+mnl-1) inclusive */
+
+#define DRM_ELD_CEA_SAD(mnl, sad)       (20 + (mnl) + 3 * (sad))
+
 struct edid {
         u8 header[8];
         /* Vendor & product info */
@@ -279,4 +334,51 @@ int
 drm_hdmi_vendor_infoframe_from_display_mode(struct hdmi_vendor_infoframe *frame,
                                             const struct drm_display_mode *mode);
 
+/**
+ * drm_eld_mnl - Get ELD monitor name length in bytes.
+ * @eld: pointer to an eld memory structure with mnl set
+ */
+static inline int drm_eld_mnl(const uint8_t *eld)
+{
+        return (eld[DRM_ELD_CEA_EDID_VER_MNL] & DRM_ELD_MNL_MASK) >> DRM_ELD_MNL_SHIFT;
+}
+
+/**
+ * drm_eld_sad_count - Get ELD SAD count.
+ * @eld: pointer to an eld memory structure with sad_count set
+ */
+static inline int drm_eld_sad_count(const uint8_t *eld)
+{
+        return (eld[DRM_ELD_SAD_COUNT_CONN_TYPE] & DRM_ELD_SAD_COUNT_MASK) >>
+                DRM_ELD_SAD_COUNT_SHIFT;
+}
+
+/**
+ * drm_eld_calc_baseline_block_size - Calculate baseline block size in bytes
+ * @eld: pointer to an eld memory structure with mnl and sad_count set
+ *
+ * This is a helper for determining the payload size of the baseline block, in
+ * bytes, for e.g. setting the Baseline_ELD_Len field in the ELD header block.
+ */
+static inline int drm_eld_calc_baseline_block_size(const uint8_t *eld)
+{
+        return DRM_ELD_MONITOR_NAME_STRING - DRM_ELD_HEADER_BLOCK_SIZE +
+                drm_eld_mnl(eld) + drm_eld_sad_count(eld) * 3;
+}
+
+/**
+ * drm_eld_size - Get ELD size in bytes
+ * @eld: pointer to a complete eld memory structure
+ *
+ * The returned value does not include the vendor block. It's vendor specific,
+ * and comprises of the remaining bytes in the ELD memory buffer after
+ * drm_eld_size() bytes of header and baseline block.
+ *
+ * The returned value is guaranteed to be a multiple of 4.
+ */
+static inline int drm_eld_size(const uint8_t *eld)
+{
+        return DRM_ELD_HEADER_BLOCK_SIZE + eld[DRM_ELD_BASELINE_ELD_LEN] * 4;
+}
+
 #endif /* __DRM_EDID_H__ */