drm/mediatek: gamma: Use bitfield macros

Make the code more robust and improve readability by using bitfield
macros instead of open coding bit operations.

Reviewed-by: Jason-JH.Lin <jason-jh.lin@mediatek.com>
Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20231012095736.100784-7-angelogioacchino.delregno@collabora.com/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

Author: AngeloGioacchino Del Regno

drivers/gpu/drm/mediatek/mtk_disp_gamma.c

@@ -3,6 +3,7 @@
  * Copyright (c) 2021 MediaTek Inc.
  */
 
+#include <linux/bitfield.h>
 #include <linux/clk.h>
 #include <linux/component.h>
 #include <linux/module.h>
@@ -21,8 +22,14 @@
 #define GAMMA_LUT_EN					BIT(1)
 #define GAMMA_DITHERING					BIT(2)
 #define DISP_GAMMA_SIZE				0x0030
+#define DISP_GAMMA_SIZE_HSIZE				GENMASK(28, 16)
+#define DISP_GAMMA_SIZE_VSIZE				GENMASK(12, 0)
 #define DISP_GAMMA_LUT				0x0700
 
+#define DISP_GAMMA_LUT_10BIT_R			GENMASK(29, 20)
+#define DISP_GAMMA_LUT_10BIT_G			GENMASK(19, 10)
+#define DISP_GAMMA_LUT_10BIT_B			GENMASK(9, 0)
+
 struct mtk_disp_gamma_data {
 	bool has_dither;
 	bool lut_diff;
@@ -97,9 +104,9 @@ void mtk_gamma_set_common(struct device *dev, void __iomem *regs, struct drm_crt
 		hwlut.blue = drm_color_lut_extract(lut[i].blue, 10);
 
 		if (!lut_diff || (i % 2 == 0)) {
-			word = (hwlut.red << 20) +
-			       (hwlut.green << 10) +
-			       hwlut.red;
+			word = FIELD_PREP(DISP_GAMMA_LUT_10BIT_R, hwlut.red);
+			word |= FIELD_PREP(DISP_GAMMA_LUT_10BIT_G, hwlut.green);
+			word |= FIELD_PREP(DISP_GAMMA_LUT_10BIT_B, hwlut.blue);
 		} else {
 			diff.red = lut[i].red - lut[i - 1].red;
 			diff.red = drm_color_lut_extract(diff.red, 10);
@@ -110,17 +117,17 @@ void mtk_gamma_set_common(struct device *dev, void __iomem *regs, struct drm_crt
 			diff.blue = lut[i].blue - lut[i - 1].blue;
 			diff.blue = drm_color_lut_extract(diff.blue, 10);
 
-			word = (diff.blue << 20) +
-			       (diff.green << 10) +
-			       diff.red;
+			word = FIELD_PREP(DISP_GAMMA_LUT_10BIT_R, diff.red);
+			word |= FIELD_PREP(DISP_GAMMA_LUT_10BIT_G, diff.green);
+			word |= FIELD_PREP(DISP_GAMMA_LUT_10BIT_B, diff.blue);
 		}
 		writel(word, lut_base + i * 4);
 	}
 
 	cfg_val = readl(regs + DISP_GAMMA_CFG);
 
 	/* Enable the gamma table */
-	cfg_val |= GAMMA_LUT_EN;
+	cfg_val |= FIELD_PREP(GAMMA_LUT_EN, 1);
 
 	writel(cfg_val, regs + DISP_GAMMA_CFG);
 }
@@ -137,9 +144,12 @@ void mtk_gamma_config(struct device *dev, unsigned int w,
 		      unsigned int bpc, struct cmdq_pkt *cmdq_pkt)
 {
 	struct mtk_disp_gamma *gamma = dev_get_drvdata(dev);
+	u32 sz;
+
+	sz = FIELD_PREP(DISP_GAMMA_SIZE_HSIZE, w);
+	sz |= FIELD_PREP(DISP_GAMMA_SIZE_VSIZE, h);
 
-	mtk_ddp_write(cmdq_pkt, h << 16 | w, &gamma->cmdq_reg, gamma->regs,
-		      DISP_GAMMA_SIZE);
+	mtk_ddp_write(cmdq_pkt, sz, &gamma->cmdq_reg, gamma->regs, DISP_GAMMA_SIZE);
 	if (gamma->data && gamma->data->has_dither)
 		mtk_dither_set_common(gamma->regs, &gamma->cmdq_reg, bpc,
 				      DISP_GAMMA_CFG, GAMMA_DITHERING, cmdq_pkt);