[PATCH v7 09/19] drm/bridge: inno-hdmi: Use a regmap for register access

[Michal Wilczynski]

On some SoCs the HDMI controller does not own its register window. The
StarFive JH7110 documents one 64 KB block, u0_hdmitx, that holds both
the controller and the PHY, so the parent device maps it and owns the
regmap while the two children share it.

Access the registers through a regmap. Use the one supplied by the
parent device when there is one, and otherwise create an MMIO regmap
over our own resource. The MMIO regmap uses 32-bit accesses with a
4-byte stride, matching the readl_relaxed() and writel_relaxed() calls
it replaces, so the Rockchip platforms see the same register accesses.

Signed-off-by: Michal Wilczynski <m.wilczynski at samsung.com>
---
 drivers/gpu/drm/bridge/Kconfig     |  1 +
 drivers/gpu/drm/bridge/inno-hdmi.c | 39 ++++++++++++++++++++++++++++++++------
 2 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
index c7da6b02d7b6b281f328fb3016ea2f167f8da093..34bcee88170317a4796178452ab5d2e673daf1fd 100644
--- a/drivers/gpu/drm/bridge/Kconfig
+++ b/drivers/gpu/drm/bridge/Kconfig
@@ -105,6 +105,7 @@ config DRM_INNO_HDMI
 	select DRM_DISPLAY_HDMI_HELPER
 	select DRM_DISPLAY_HELPER
 	select DRM_KMS_HELPER
+	select REGMAP_MMIO
 
 config DRM_ITE_IT6263
 	tristate "ITE IT6263 LVDS/HDMI bridge"
diff --git a/drivers/gpu/drm/bridge/inno-hdmi.c b/drivers/gpu/drm/bridge/inno-hdmi.c
index aa64ffdbd30721603aebbcd5d5747851be789911..05007ed1d7af0b0f72721a0fd4def08fa621b525 100644
--- a/drivers/gpu/drm/bridge/inno-hdmi.c
+++ b/drivers/gpu/drm/bridge/inno-hdmi.c
@@ -396,7 +396,7 @@ struct inno_hdmi {
 	struct drm_bridge bridge;
 	struct clk *pclk;
 	struct clk *refclk;
-	void __iomem *regs;
+	struct regmap *regmap;
 	struct regmap *grf;
 
 	struct inno_hdmi_i2c *i2c;
@@ -468,14 +468,25 @@ static int inno_hdmi_find_phy_config(struct inno_hdmi *hdmi,
 	return -EINVAL;
 }
 
+static const struct regmap_config inno_hdmi_regmap_config = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = 4,
+};
+
 static inline u8 hdmi_readb(struct inno_hdmi *hdmi, u16 offset)
 {
-	return readl_relaxed(hdmi->regs + (offset) * 0x04);
+	u32 val;
+
+	if (regmap_read(hdmi->regmap, offset * 4, &val))
+		return 0;
+
+	return val;
 }
 
 static inline void hdmi_writeb(struct inno_hdmi *hdmi, u16 offset, u32 val)
 {
-	writel_relaxed(val, hdmi->regs + (offset) * 0x04);
+	regmap_write(hdmi->regmap, offset * 4, val);
 }
 
 static inline void hdmi_modb(struct inno_hdmi *hdmi, u16 offset,
@@ -1082,6 +1093,7 @@ struct inno_hdmi *inno_hdmi_probe(struct platform_device *pdev,
 {
 	struct device *dev = &pdev->dev;
 	struct inno_hdmi *hdmi;
+	void __iomem *regs;
 	int irq;
 	int ret;
 
@@ -1097,9 +1109,24 @@ struct inno_hdmi *inno_hdmi_probe(struct platform_device *pdev,
 	hdmi->dev = dev;
 	hdmi->plat_data = plat_data;
 
-	hdmi->regs = devm_platform_ioremap_resource(pdev, 0);
-	if (IS_ERR(hdmi->regs))
-		return ERR_CAST(hdmi->regs);
+	/*
+	 * On platforms where the controller shares a register space with
+	 * other blocks, the parent owns the regmap. Otherwise map our own
+	 * resource.
+	 */
+	if (dev->parent)
+		hdmi->regmap = dev_get_regmap(dev->parent, NULL);
+
+	if (!hdmi->regmap) {
+		regs = devm_platform_ioremap_resource(pdev, 0);
+		if (IS_ERR(regs))
+			return ERR_CAST(regs);
+
+		hdmi->regmap = devm_regmap_init_mmio(dev, regs,
+						     &inno_hdmi_regmap_config);
+		if (IS_ERR(hdmi->regmap))
+			return ERR_CAST(hdmi->regmap);
+	}
 
 	hdmi->pclk = devm_clk_get_enabled(hdmi->dev, "pclk");
 	if (IS_ERR(hdmi->pclk)) {

-- 
2.34.1