1 files changed, 96 insertions, 0 deletions
diff --git a/drivers/gpu/drm/msm/dp/dp_utils.c b/drivers/gpu/drm/msm/dp/dp_utils.c
new file mode 100644
index 0000000000..da9207caf7
--- /dev/null
+++ b/drivers/gpu/drm/msm/dp/dp_utils.c
@@ -0,0 +1,96 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2024, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/types.h>
+
+#include "dp_utils.h"
+
+#define DP_SDP_HEADER_SIZE		8
+
+u8 dp_utils_get_g0_value(u8 data)
+{
+	u8 c[4];
+	u8 g[4];
+	u8 ret_data = 0;
+	u8 i;
+
+	for (i = 0; i < 4; i++)
+		c[i] = (data >> i) & 0x01;
+
+	g[0] = c[3];
+	g[1] = c[0] ^ c[3];
+	g[2] = c[1];
+	g[3] = c[2];
+
+	for (i = 0; i < 4; i++)
+		ret_data = ((g[i] & 0x01) << i) | ret_data;
+
+	return ret_data;
+}
+
+u8 dp_utils_get_g1_value(u8 data)
+{
+	u8 c[4];
+	u8 g[4];
+	u8 ret_data = 0;
+	u8 i;
+
+	for (i = 0; i < 4; i++)
+		c[i] = (data >> i) & 0x01;
+
+	g[0] = c[0] ^ c[3];
+	g[1] = c[0] ^ c[1] ^ c[3];
+	g[2] = c[1] ^ c[2];
+	g[3] = c[2] ^ c[3];
+
+	for (i = 0; i < 4; i++)
+		ret_data = ((g[i] & 0x01) << i) | ret_data;
+
+	return ret_data;
+}
+
+u8 dp_utils_calculate_parity(u32 data)
+{
+	u8 x0 = 0;
+	u8 x1 = 0;
+	u8 ci = 0;
+	u8 iData = 0;
+	u8 i = 0;
+	u8 parity_byte;
+	u8 num_byte = (data & 0xFF00) > 0 ? 8 : 2;
+
+	for (i = 0; i < num_byte; i++) {
+		iData = (data >> i * 4) & 0xF;
+
+		ci = iData ^ x1;
+		x1 = x0 ^ dp_utils_get_g1_value(ci);
+		x0 = dp_utils_get_g0_value(ci);
+	}
+
+	parity_byte = x1 | (x0 << 4);
+
+	return parity_byte;
+}
+
+ssize_t dp_utils_pack_sdp_header(struct dp_sdp_header *sdp_header, u32 *header_buff)
+{
+	size_t length;
+
+	length = sizeof(header_buff);
+	if (length < DP_SDP_HEADER_SIZE)
+		return -ENOSPC;
+
+	header_buff[0] = FIELD_PREP(HEADER_0_MASK, sdp_header->HB0) |
+		FIELD_PREP(PARITY_0_MASK, dp_utils_calculate_parity(sdp_header->HB0)) |
+		FIELD_PREP(HEADER_1_MASK, sdp_header->HB1) |
+		FIELD_PREP(PARITY_1_MASK, dp_utils_calculate_parity(sdp_header->HB1));
+
+	header_buff[1] = FIELD_PREP(HEADER_2_MASK, sdp_header->HB2) |
+		FIELD_PREP(PARITY_2_MASK, dp_utils_calculate_parity(sdp_header->HB2)) |
+		FIELD_PREP(HEADER_3_MASK, sdp_header->HB3) |
+		FIELD_PREP(PARITY_3_MASK, dp_utils_calculate_parity(sdp_header->HB3));
+
+	return length;
+}