This is a preparation commit to add support for new variants of the
decoder.

The functions will later be shared with vdpu381 (rk3588) and vdpu383
(rk3576).

Tested-by: Diederik de Haas <redacted>  # Rock 5B
Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
---
 .../media/platform/rockchip/rkvdec/Makefile   |   1 +
 .../rockchip/rkvdec/rkvdec-hevc-common.c      | 233 +++++++++++++++++
 .../rockchip/rkvdec/rkvdec-hevc-common.h      |  51 ++++
 .../platform/rockchip/rkvdec/rkvdec-hevc.c    | 243 +-----------------
 4 files changed, 291 insertions(+), 237 deletions(-)
 create mode 100644 drivers/media/platform/rockchip/rkvdec/rkvdec-hevc-common.c
 create mode 100644 drivers/media/platform/rockchip/rkvdec/rkvdec-hevc-common.h

diff --git a/drivers/media/platform/rockchip/rkvdec/Makefile b/drivers/media/platform/rockchip/rkvdec/Makefile
index d2ba7a7c15e5..1b4bc44be23e 100644
--- a/drivers/media/platform/rockchip/rkvdec/Makefile
+++ b/drivers/media/platform/rockchip/rkvdec/Makefile

@@ -6,4 +6,5 @@ rockchip-vdec-y += \
 		   rkvdec-h264.o \
 		   rkvdec-h264-common.o \
 		   rkvdec-hevc.o \
+		   rkvdec-hevc-common.o \
 		   rkvdec-vp9.o

diff --git a/drivers/media/platform/rockchip/rkvdec/rkvdec-hevc-common.c b/drivers/media/platform/rockchip/rkvdec/rkvdec-hevc-common.c
new file mode 100644
index 000000000000..d571107f2242
--- /dev/null
+++ b/drivers/media/platform/rockchip/rkvdec/rkvdec-hevc-common.c

@@ -0,0 +1,233 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Rockchip video decoder hevc common functions
+ *
+ * Copyright (C) 2025 Collabora, Ltd.
+ *      Detlev Casanova <detlev.casanova@collabora.com>
+ *
+ * Copyright (C) 2023 Collabora, Ltd.
+ *      Sebastian Fricke <sebastian.fricke@collabora.com>
+ *
+ * Copyright (C) 2019 Collabora, Ltd.
+ *	Boris Brezillon <boris.brezillon@collabora.com>
+ *
+ * Copyright (C) 2016 Rockchip Electronics Co., Ltd.
+ *	Jeffy Chen <jeffy.chen@rock-chips.com>
+ */
+
+#include <linux/v4l2-common.h>
+#include <media/v4l2-mem2mem.h>
+
+#include "rkvdec.h"
+#include "rkvdec-hevc-common.h"
+
+/*
+ * Flip one or more matrices along their main diagonal and flatten them
+ * before writing it to the memory.
+ * Convert:
+ * ABCD         AEIM
+ * EFGH     =>  BFJN     =>     AEIMBFJNCGKODHLP
+ * IJKL         CGKO
+ * MNOP         DHLP
+ */
+static void transpose_and_flatten_matrices(u8 *output, const u8 *input,
+					   int matrices, int row_length)
+{
+	int i, j, row, x_offset, matrix_offset, rot_index, y_offset, matrix_size, new_value;
+
+	matrix_size = row_length * row_length;
+	for (i = 0; i < matrices; i++) {
+		row = 0;
+		x_offset = 0;
+		matrix_offset = i * matrix_size;
+		for (j = 0; j < matrix_size; j++) {
+			y_offset = j - (row * row_length);
+			rot_index = y_offset * row_length + x_offset;
+			new_value = *(input + i * matrix_size + j);
+			output[matrix_offset + rot_index] = new_value;
+			if ((j + 1) % row_length == 0) {
+				row += 1;
+				x_offset += 1;
+			}
+		}
+	}
+}
+
+static void assemble_scalingfactor0(u8 *output, const struct v4l2_ctrl_hevc_scaling_matrix *input)
+{
+	int offset = 0;
+
+	transpose_and_flatten_matrices(output, (const u8 *)input->scaling_list_4x4, 6, 4);
+	offset = 6 * 16 * sizeof(u8);
+	transpose_and_flatten_matrices(output + offset, (const u8 *)input->scaling_list_8x8, 6, 8);
+	offset += 6 * 64 * sizeof(u8);
+	transpose_and_flatten_matrices(output + offset,
+				       (const u8 *)input->scaling_list_16x16, 6, 8);
+	offset += 6 * 64 * sizeof(u8);
+	/* Add a 128 byte padding with 0s between the two 32x32 matrices */
+	transpose_and_flatten_matrices(output + offset,
+				       (const u8 *)input->scaling_list_32x32, 1, 8);
+	offset += 64 * sizeof(u8);
+	memset(output + offset, 0, 128);
+	offset += 128 * sizeof(u8);
+	transpose_and_flatten_matrices(output + offset,
+				       (const u8 *)input->scaling_list_32x32 + (64 * sizeof(u8)),
+				       1, 8);
+	offset += 64 * sizeof(u8);
+	memset(output + offset, 0, 128);
+}
+
+/*
+ * Required layout:
+ * A = scaling_list_dc_coef_16x16
+ * B = scaling_list_dc_coef_32x32
+ * 0 = Padding
+ *
+ * A, A, A, A, A, A, B, 0, 0, B, 0, 0
+ */
+static void assemble_scalingdc(u8 *output, const struct v4l2_ctrl_hevc_scaling_matrix *input)
+{
+	u8 list_32x32[6] = {0};
+
+	memcpy(output, input->scaling_list_dc_coef_16x16, 6 * sizeof(u8));
+	list_32x32[0] = input->scaling_list_dc_coef_32x32[0];
+	list_32x32[3] = input->scaling_list_dc_coef_32x32[1];
+	memcpy(output + 6 * sizeof(u8), list_32x32, 6 * sizeof(u8));
+}
+
+static void translate_scaling_list(struct scaling_factor *output,
+				   const struct v4l2_ctrl_hevc_scaling_matrix *input)
+{
+	assemble_scalingfactor0(output->scalingfactor0, input);
+	memcpy(output->scalingfactor1, (const u8 *)input->scaling_list_4x4, 96);
+	assemble_scalingdc(output->scalingdc, input);
+	memset(output->reserved, 0, 4 * sizeof(u8));
+}
+
+void rkvdec_hevc_assemble_hw_scaling_list(struct rkvdec_hevc_run *run,
+					  struct scaling_factor *scaling_factor,
+					  struct v4l2_ctrl_hevc_scaling_matrix *cache)
+{
+	const struct v4l2_ctrl_hevc_scaling_matrix *scaling = run->scaling_matrix;
+
+	if (!memcmp(cache, scaling,
+		    sizeof(struct v4l2_ctrl_hevc_scaling_matrix)))
+		return;
+
+	translate_scaling_list(scaling_factor, scaling);
+
+	memcpy(cache, scaling,
+	       sizeof(struct v4l2_ctrl_hevc_scaling_matrix));
+}
+
+struct vb2_buffer *
+get_ref_buf(struct rkvdec_ctx *ctx, struct rkvdec_hevc_run *run,
+	    unsigned int dpb_idx)
+{
+	struct v4l2_m2m_ctx *m2m_ctx = ctx->fh.m2m_ctx;
+	const struct v4l2_ctrl_hevc_decode_params *decode_params = run->decode_params;
+	const struct v4l2_hevc_dpb_entry *dpb = decode_params->dpb;
+	struct vb2_queue *cap_q = &m2m_ctx->cap_q_ctx.q;
+	struct vb2_buffer *buf = NULL;
+
+	if (dpb_idx < decode_params->num_active_dpb_entries)
+		buf = vb2_find_buffer(cap_q, dpb[dpb_idx].timestamp);
+
+	/*
+	 * If a DPB entry is unused or invalid, the address of current destination
+	 * buffer is returned.
+	 */
+	if (!buf)
+		return &run->base.bufs.dst->vb2_buf;
+
+	return buf;
+}
+
+#define RKVDEC_HEVC_MAX_DEPTH_IN_BYTES		2
+
+int rkvdec_hevc_adjust_fmt(struct rkvdec_ctx *ctx, struct v4l2_format *f)
+{
+	struct v4l2_pix_format_mplane *fmt = &f->fmt.pix_mp;
+
+	fmt->num_planes = 1;
+	if (!fmt->plane_fmt[0].sizeimage)
+		fmt->plane_fmt[0].sizeimage = fmt->width * fmt->height *
+					      RKVDEC_HEVC_MAX_DEPTH_IN_BYTES;
+	return 0;
+}
+
+enum rkvdec_image_fmt rkvdec_hevc_get_image_fmt(struct rkvdec_ctx *ctx,
+						struct v4l2_ctrl *ctrl)
+{
+	const struct v4l2_ctrl_hevc_sps *sps = ctrl->p_new.p_hevc_sps;
+
+	if (ctrl->id != V4L2_CID_STATELESS_HEVC_SPS)
+		return RKVDEC_IMG_FMT_ANY;
+
+	if (sps->bit_depth_luma_minus8 == 0) {
+		if (sps->chroma_format_idc == 2)
+			return RKVDEC_IMG_FMT_422_8BIT;
+		else
+			return RKVDEC_IMG_FMT_420_8BIT;
+	} else if (sps->bit_depth_luma_minus8 == 2) {
+		if (sps->chroma_format_idc == 2)
+			return RKVDEC_IMG_FMT_422_10BIT;
+		else
+			return RKVDEC_IMG_FMT_420_10BIT;
+	}
+
+	return RKVDEC_IMG_FMT_ANY;
+}