drm/mediatek: Support MT8188 Padding in display driver

Padding is a new display module on MT8188, it provides ability
to add pixels to width and height of a layer with specified colors.

Due to hardware design, Mixer in VDOSYS1 requires width of a layer
to be 2-pixel-align, or 4-pixel-align when ETHDR is enabled,
we need Padding to deal with odd width.

Reviewed-by: CK Hu <ck.hu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Hsiao Chien Sung <shawn.sung@mediatek.com>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20231214055847.4936-19-shawn.sung@mediatek.com/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

drivers/gpu/drm/mediatek/Makefile

@@ -16,7 +16,8 @@ mediatek-drm-y := mtk_disp_aal.o \
 		  mtk_dsi.o \
 		  mtk_dpi.o \
 		  mtk_ethdr.o \
-		  mtk_mdp_rdma.o
+		  mtk_mdp_rdma.o \
+		  mtk_padding.o
 
 obj-$(CONFIG_DRM_MEDIATEK) += mediatek-drm.o
 

drivers/gpu/drm/mediatek/mtk_disp_drv.h

@@ -164,4 +164,8 @@ void mtk_mdp_rdma_config(struct device *dev, struct mtk_mdp_rdma_cfg *cfg,
 const u32 *mtk_mdp_rdma_get_formats(struct device *dev);
 size_t mtk_mdp_rdma_get_num_formats(struct device *dev);
 
+int mtk_padding_clk_enable(struct device *dev);
+void mtk_padding_clk_disable(struct device *dev);
+void mtk_padding_start(struct device *dev);
+void mtk_padding_stop(struct device *dev);
 #endif

drivers/gpu/drm/mediatek/mtk_drm_drv.c

@@ -996,6 +996,7 @@ static struct platform_driver * const mtk_drm_drivers[] = {
 	&mtk_dsi_driver,
 	&mtk_ethdr_driver,
 	&mtk_mdp_rdma_driver,
+	&mtk_padding_driver,
 };
 
 static int __init mtk_drm_init(void)

drivers/gpu/drm/mediatek/mtk_drm_drv.h

@@ -77,5 +77,5 @@ extern struct platform_driver mtk_dpi_driver;
 extern struct platform_driver mtk_dsi_driver;
 extern struct platform_driver mtk_ethdr_driver;
 extern struct platform_driver mtk_mdp_rdma_driver;
-
+extern struct platform_driver mtk_padding_driver;
 #endif /* MTK_DRM_DRV_H */

drivers/gpu/drm/mediatek/mtk_padding.c

@@ -0,0 +1,160 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2023 MediaTek Inc.
+ */
+
+#include <linux/clk.h>
+#include <linux/component.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/soc/mediatek/mtk-cmdq.h>
+
+#include "mtk_disp_drv.h"
+#include "mtk_drm_crtc.h"
+#include "mtk_drm_ddp_comp.h"
+
+#define PADDING_CONTROL_REG	0x00
+#define PADDING_BYPASS			BIT(0)
+#define PADDING_ENABLE			BIT(1)
+#define PADDING_PIC_SIZE_REG	0x04
+#define PADDING_H_REG		0x08 /* horizontal */
+#define PADDING_V_REG		0x0c /* vertical */
+#define PADDING_COLOR_REG	0x10
+
+/**
+ * struct mtk_padding - Basic information of the Padding
+ * @clk: Clock of the module
+ * @reg: Virtual address of the Padding for CPU to access
+ * @cmdq_reg: CMDQ setting of the Padding
+ *
+ * Every Padding should have different clock source, register base, and
+ * CMDQ settings, we stored these differences all together.
+ */
+struct mtk_padding {
+	struct clk		*clk;
+	void __iomem		*reg;
+	struct cmdq_client_reg	cmdq_reg;
+};
+
+int mtk_padding_clk_enable(struct device *dev)
+{
+	struct mtk_padding *padding = dev_get_drvdata(dev);
+
+	return clk_prepare_enable(padding->clk);
+}
+
+void mtk_padding_clk_disable(struct device *dev)
+{
+	struct mtk_padding *padding = dev_get_drvdata(dev);
+
+	clk_disable_unprepare(padding->clk);
+}
+
+void mtk_padding_start(struct device *dev)
+{
+	struct mtk_padding *padding = dev_get_drvdata(dev);
+
+	writel(PADDING_ENABLE | PADDING_BYPASS,
+	       padding->reg + PADDING_CONTROL_REG);
+
+	/*
+	 * Notice that even the padding is in bypass mode,
+	 * all the settings must be cleared to 0 or
+	 * undefined behaviors could happen
+	 */
+	writel(0, padding->reg + PADDING_PIC_SIZE_REG);
+	writel(0, padding->reg + PADDING_H_REG);
+	writel(0, padding->reg + PADDING_V_REG);
+	writel(0, padding->reg + PADDING_COLOR_REG);
+}
+
+void mtk_padding_stop(struct device *dev)
+{
+	struct mtk_padding *padding = dev_get_drvdata(dev);
+
+	writel(0, padding->reg + PADDING_CONTROL_REG);
+}
+
+static int mtk_padding_bind(struct device *dev, struct device *master, void *data)
+{
+	return 0;
+}
+
+static void mtk_padding_unbind(struct device *dev, struct device *master, void *data)
+{
+}
+
+static const struct component_ops mtk_padding_component_ops = {
+	.bind	= mtk_padding_bind,
+	.unbind = mtk_padding_unbind,
+};
+
+static int mtk_padding_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct mtk_padding *priv;
+	struct resource *res;
+	int ret;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(priv->clk)) {
+		dev_err(dev, "failed to get clk\n");
+		return PTR_ERR(priv->clk);
+	}
+
+	priv->reg = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+	if (IS_ERR(priv->reg)) {
+		dev_err(dev, "failed to do ioremap\n");
+		return PTR_ERR(priv->reg);
+	}
+
+#if IS_REACHABLE(CONFIG_MTK_CMDQ)
+	ret = cmdq_dev_get_client_reg(dev, &priv->cmdq_reg, 0);
+	if (ret) {
+		dev_err(dev, "failed to get gce client reg\n");
+		return ret;
+	}
+#endif
+
+	platform_set_drvdata(pdev, priv);
+
+	ret = devm_pm_runtime_enable(dev);
+	if (ret)
+		return ret;
+
+	ret = component_add(dev, &mtk_padding_component_ops);
+	if (ret) {
+		pm_runtime_disable(dev);
+		return dev_err_probe(dev, ret, "failed to add component\n");
+	}
+
+	return 0;
+}
+
+static int mtk_padding_remove(struct platform_device *pdev)
+{
+	component_del(&pdev->dev, &mtk_padding_component_ops);
+	return 0;
+}
+
+static const struct of_device_id mtk_padding_driver_dt_match[] = {
+	{ .compatible = "mediatek,mt8188-disp-padding" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, mtk_padding_driver_dt_match);
+
+struct platform_driver mtk_padding_driver = {
+	.probe		= mtk_padding_probe,
+	.remove		= mtk_padding_remove,
+	.driver		= {
+		.name	= "mediatek-disp-padding",
+		.owner	= THIS_MODULE,
+		.of_match_table = mtk_padding_driver_dt_match,
+	},
+};