drm/msm/dp: move parity calculation to dp_utils

Parity calculation is necessary for VSC SDP implementation. Therefore
create new files dp_utils.c and dp_utils.h and move the parity
calculating functions here. This ensures that they are usable by SDP
programming in both dp_catalog.c and dp_audio.c

Changes in v3:
	- Change ordering of the header byte macros

Changes in v2:
	- Create new files dp_utils.c and dp_utils.h
	- Move the parity calculation to these new files instead of
	  having them in dp_catalog.c and dp_catalog.h

Signed-off-by: Paloma Arellano <quic_parellan@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/579617/
Link: https://lore.kernel.org/r/20240222194025.25329-13-quic_parellan@quicinc.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

1 files changed, 73 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 000000000000..3a44fe738c00
--- /dev/null
+++ b/drivers/gpu/drm/msm/dp/dp_utils.c
@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2024, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/types.h>
+
+#include "dp_utils.h"
+
+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;
+}