drm: bridge: dw-hdmi: Switch to regmap for register access

The Synopsys Designware HDMI TX Controller does not enforce register
access on platforms instanciating it. The current driver supports two
different types of memory-mapped flat register access, but in order to
support the Amlogic Meson SoCs integration, and provide a more generic
way to handle all sorts of register mapping, switch the register access
to use the regmap infrastructure.

In the case of registers that are not flat memory-mapped or do not
conform to the current driver implementation, a regmap struct can be
given in the plat_data and be used at probe or bind.

Since the AHB audio driver is only available with direct memory access,
only allow the I2S audio driver to be registered is directly
memory-mapped.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Tested-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Tested-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Jose Abreu <Jose.Abreu@synopsys.com>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20170303172007.26541-10-laurent.pinchart+renesas@ideasonboard.com

drivers/gpu/drm/bridge/dw-hdmi.c

@@ -19,6 +19,7 @@
 #include <linux/hdmi.h>
 #include <linux/mutex.h>
 #include <linux/of_device.h>
+#include <linux/regmap.h>
 #include <linux/spinlock.h>
 
 #include <drm/drm_of.h>
@@ -171,8 +172,8 @@ struct dw_hdmi {
 	unsigned int audio_n;
 	bool audio_enable;
 
-	void (*write)(struct dw_hdmi *hdmi, u8 val, int offset);
-	u8 (*read)(struct dw_hdmi *hdmi, int offset);
+	unsigned int reg_shift;
+	struct regmap *regm;
 };
 
 #define HDMI_IH_PHY_STAT0_RX_SENSE \
@@ -183,42 +184,23 @@ struct dw_hdmi {
 	(HDMI_PHY_RX_SENSE0 | HDMI_PHY_RX_SENSE1 | \
 	 HDMI_PHY_RX_SENSE2 | HDMI_PHY_RX_SENSE3)
 
-static void dw_hdmi_writel(struct dw_hdmi *hdmi, u8 val, int offset)
-{
-	writel(val, hdmi->regs + (offset << 2));
-}
-
-static u8 dw_hdmi_readl(struct dw_hdmi *hdmi, int offset)
-{
-	return readl(hdmi->regs + (offset << 2));
-}
-
-static void dw_hdmi_writeb(struct dw_hdmi *hdmi, u8 val, int offset)
-{
-	writeb(val, hdmi->regs + offset);
-}
-
-static u8 dw_hdmi_readb(struct dw_hdmi *hdmi, int offset)
-{
-	return readb(hdmi->regs + offset);
-}
-
 static inline void hdmi_writeb(struct dw_hdmi *hdmi, u8 val, int offset)
 {
-	hdmi->write(hdmi, val, offset);
+	regmap_write(hdmi->regm, offset << hdmi->reg_shift, val);
 }
 
 static inline u8 hdmi_readb(struct dw_hdmi *hdmi, int offset)
 {
-	return hdmi->read(hdmi, offset);
+	unsigned int val = 0;
+
+	regmap_read(hdmi->regm, offset << hdmi->reg_shift, &val);
+
+	return val;
 }
 
 static void hdmi_modb(struct dw_hdmi *hdmi, u8 data, u8 mask, unsigned reg)
 {
-	u8 val = hdmi_readb(hdmi, reg) & ~mask;
-
-	val |= data & mask;
-	hdmi_writeb(hdmi, val, reg);
+	regmap_update_bits(hdmi->regm, reg << hdmi->reg_shift, mask, data);
 }
 
 static void hdmi_mask_writeb(struct dw_hdmi *hdmi, u8 data, unsigned int reg,
@@ -1989,6 +1971,20 @@ static int dw_hdmi_detect_phy(struct dw_hdmi *hdmi)
 	return -ENODEV;
 }
 
+static const struct regmap_config hdmi_regmap_8bit_config = {
+	.reg_bits	= 32,
+	.val_bits	= 8,
+	.reg_stride	= 1,
+	.max_register	= HDMI_I2CM_FS_SCL_LCNT_0_ADDR,
+};
+
+static const struct regmap_config hdmi_regmap_32bit_config = {
+	.reg_bits	= 32,
+	.val_bits	= 32,
+	.reg_stride	= 4,
+	.max_register	= HDMI_I2CM_FS_SCL_LCNT_0_ADDR << 2,
+};
+
 static struct dw_hdmi *
 __dw_hdmi_probe(struct platform_device *pdev,
 		const struct dw_hdmi_plat_data *plat_data)
@@ -1998,7 +1994,7 @@ __dw_hdmi_probe(struct platform_device *pdev,
 	struct platform_device_info pdevinfo;
 	struct device_node *ddc_node;
 	struct dw_hdmi *hdmi;
-	struct resource *iores;
+	struct resource *iores = NULL;
 	int irq;
 	int ret;
 	u32 val = 1;
@@ -2022,22 +2018,6 @@ __dw_hdmi_probe(struct platform_device *pdev,
 	mutex_init(&hdmi->audio_mutex);
 	spin_lock_init(&hdmi->audio_lock);
 
-	of_property_read_u32(np, "reg-io-width", &val);
-
-	switch (val) {
-	case 4:
-		hdmi->write = dw_hdmi_writel;
-		hdmi->read = dw_hdmi_readl;
-		break;
-	case 1:
-		hdmi->write = dw_hdmi_writeb;
-		hdmi->read = dw_hdmi_readb;
-		break;
-	default:
-		dev_err(dev, "reg-io-width must be 1 or 4\n");
-		return ERR_PTR(-EINVAL);
-	}
-
 	ddc_node = of_parse_phandle(np, "ddc-i2c-bus", 0);
 	if (ddc_node) {
 		hdmi->ddc = of_get_i2c_adapter_by_node(ddc_node);
@@ -2051,11 +2031,38 @@ __dw_hdmi_probe(struct platform_device *pdev,
 		dev_dbg(hdmi->dev, "no ddc property found\n");
 	}
 
-	iores = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	hdmi->regs = devm_ioremap_resource(dev, iores);
-	if (IS_ERR(hdmi->regs)) {
-		ret = PTR_ERR(hdmi->regs);
-		goto err_res;
+	if (!plat_data->regm) {
+		const struct regmap_config *reg_config;
+
+		of_property_read_u32(np, "reg-io-width", &val);
+		switch (val) {
+		case 4:
+			reg_config = &hdmi_regmap_32bit_config;
+			hdmi->reg_shift = 2;
+			break;
+		case 1:
+			reg_config = &hdmi_regmap_8bit_config;
+			break;
+		default:
+			dev_err(dev, "reg-io-width must be 1 or 4\n");
+			return ERR_PTR(-EINVAL);
+		}
+
+		iores = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+		hdmi->regs = devm_ioremap_resource(dev, iores);
+		if (IS_ERR(hdmi->regs)) {
+			ret = PTR_ERR(hdmi->regs);
+			goto err_res;
+		}
+
+		hdmi->regm = devm_regmap_init_mmio(dev, hdmi->regs, reg_config);
+		if (IS_ERR(hdmi->regm)) {
+			dev_err(dev, "Failed to configure regmap\n");
+			ret = PTR_ERR(hdmi->regm);
+			goto err_res;
+		}
+	} else {
+		hdmi->regm = plat_data->regm;
 	}
 
 	hdmi->isfr_clk = devm_clk_get(hdmi->dev, "isfr");
@@ -2165,7 +2172,7 @@ __dw_hdmi_probe(struct platform_device *pdev,
 	config0 = hdmi_readb(hdmi, HDMI_CONFIG0_ID);
 	config3 = hdmi_readb(hdmi, HDMI_CONFIG3_ID);
 
-	if (config3 & HDMI_CONFIG3_AHBAUDDMA) {
+	if (iores && config3 & HDMI_CONFIG3_AHBAUDDMA) {
 		struct dw_hdmi_audio_data audio;
 
 		audio.phys = iores->start;

include/drm/bridge/dw_hdmi.h

@@ -59,6 +59,7 @@ struct dw_hdmi_phy_ops {
 };
 
 struct dw_hdmi_plat_data {
+	struct regmap *regm;
 	enum drm_mode_status (*mode_valid)(struct drm_connector *connector,
 					   struct drm_display_mode *mode);