drm: bridge: icn6211: Convert to regmap

To make debugging easier, convert driver to regmap. Implement read and write
regmap tables for known registers, keep all known register readable and mark
those which are obviously read-only as not writeable.

Use common I2C regmap for the I2C configuration, implement custom regmap bus
for DSI configuration. The later is mandatory as this chip requires one extra
byte set to read access length between register address and data.
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Jagan Teki <jagan@amarulasolutions.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Maxime Ripard <maxime@cerno.tech>
Cc: Robert Foss <robert.foss@linaro.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
To: dri-devel@lists.freedesktop.org
Acked-by: Mark Brown <broonie@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220403171004.368464-1-marex@denx.de

drivers/gpu/drm/bridge/Kconfig

@@ -32,6 +32,7 @@ config DRM_CHIPONE_ICN6211
 	select DRM_KMS_HELPER
 	select DRM_MIPI_DSI
 	select DRM_PANEL_BRIDGE
+	select REGMAP_I2C
 	help
 	  ICN6211 is MIPI-DSI/RGB Converter bridge from chipone.
 

drivers/gpu/drm/bridge/chipone-icn6211.c

@@ -14,6 +14,7 @@
 #include <linux/i2c.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
+#include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
 
 #define VENDOR_ID		0x00
@@ -134,6 +135,7 @@
 
 struct chipone {
 	struct device *dev;
+	struct regmap *regmap;
 	struct i2c_client *client;
 	struct drm_bridge bridge;
 	struct drm_display_mode mode;
@@ -146,6 +148,77 @@ struct chipone {
 	bool interface_i2c;
 };
 
+static const struct regmap_range chipone_dsi_readable_ranges[] = {
+	regmap_reg_range(VENDOR_ID, VERSION_ID),
+	regmap_reg_range(FIRMWARE_VERSION, PLL_SSC_OFFSET(3)),
+	regmap_reg_range(GPIO_OEN, MIPI_ULPS_CTRL),
+	regmap_reg_range(MIPI_CLK_CHK_VAR, MIPI_T_TA_SURE_PRE),
+	regmap_reg_range(MIPI_T_LPX_SET, MIPI_INIT_TIME_H),
+	regmap_reg_range(MIPI_T_CLK_TERM_EN, MIPI_T_CLK_SETTLE),
+	regmap_reg_range(MIPI_TO_HS_RX_L, MIPI_PHY_(5)),
+	regmap_reg_range(MIPI_PD_RX, MIPI_RST_NUM),
+	regmap_reg_range(MIPI_DBG_SET_(0), MIPI_DBG_SET_(9)),
+	regmap_reg_range(MIPI_DBG_SEL, MIPI_ATE_STATUS_(1)),
+};
+
+static const struct regmap_access_table chipone_dsi_readable_table = {
+	.yes_ranges = chipone_dsi_readable_ranges,
+	.n_yes_ranges = ARRAY_SIZE(chipone_dsi_readable_ranges),
+};
+
+static const struct regmap_range chipone_dsi_writeable_ranges[] = {
+	regmap_reg_range(CONFIG_FINISH, PLL_SSC_OFFSET(3)),
+	regmap_reg_range(GPIO_OEN, MIPI_ULPS_CTRL),
+	regmap_reg_range(MIPI_CLK_CHK_VAR, MIPI_T_TA_SURE_PRE),
+	regmap_reg_range(MIPI_T_LPX_SET, MIPI_INIT_TIME_H),
+	regmap_reg_range(MIPI_T_CLK_TERM_EN, MIPI_T_CLK_SETTLE),
+	regmap_reg_range(MIPI_TO_HS_RX_L, MIPI_PHY_(5)),
+	regmap_reg_range(MIPI_PD_RX, MIPI_RST_NUM),
+	regmap_reg_range(MIPI_DBG_SET_(0), MIPI_DBG_SET_(9)),
+	regmap_reg_range(MIPI_DBG_SEL, MIPI_ATE_STATUS_(1)),
+};
+
+static const struct regmap_access_table chipone_dsi_writeable_table = {
+	.yes_ranges = chipone_dsi_writeable_ranges,
+	.n_yes_ranges = ARRAY_SIZE(chipone_dsi_writeable_ranges),
+};
+
+static const struct regmap_config chipone_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.rd_table = &chipone_dsi_readable_table,
+	.wr_table = &chipone_dsi_writeable_table,
+	.cache_type = REGCACHE_RBTREE,
+	.max_register = MIPI_ATE_STATUS_(1),
+};
+
+static int chipone_dsi_read(void *context,
+			    const void *reg, size_t reg_size,
+			    void *val, size_t val_size)
+{
+	struct mipi_dsi_device *dsi = context;
+	const u16 reg16 = (val_size << 8) | *(u8 *)reg;
+	int ret;
+
+	ret = mipi_dsi_generic_read(dsi, &reg16, 2, val, val_size);
+
+	return ret == val_size ? 0 : -EINVAL;
+}
+
+static int chipone_dsi_write(void *context, const void *data, size_t count)
+{
+	struct mipi_dsi_device *dsi = context;
+
+	return mipi_dsi_generic_write(dsi, data, 2);
+}
+
+static const struct regmap_bus chipone_dsi_regmap_bus = {
+	.read				= chipone_dsi_read,
+	.write				= chipone_dsi_write,
+	.reg_format_endian_default	= REGMAP_ENDIAN_NATIVE,
+	.val_format_endian_default	= REGMAP_ENDIAN_NATIVE,
+};
+
 static inline struct chipone *bridge_to_chipone(struct drm_bridge *bridge)
 {
 	return container_of(bridge, struct chipone, bridge);
@@ -153,18 +226,16 @@ static inline struct chipone *bridge_to_chipone(struct drm_bridge *bridge)
 
 static void chipone_readb(struct chipone *icn, u8 reg, u8 *val)
 {
-	if (icn->interface_i2c)
-		*val = i2c_smbus_read_byte_data(icn->client, reg);
-	else
-		mipi_dsi_generic_read(icn->dsi, (u8[]){reg, 1}, 2, val, 1);
+	int ret, pval;
+
+	ret = regmap_read(icn->regmap, reg, &pval);
+
+	*val = ret ? 0 : pval & 0xff;
 }
 
 static int chipone_writeb(struct chipone *icn, u8 reg, u8 val)
 {
-	if (icn->interface_i2c)
-		return i2c_smbus_write_byte_data(icn->client, reg, val);
-	else
-		return mipi_dsi_generic_write(icn->dsi, (u8[]){reg, val}, 2);
+	return regmap_write(icn->regmap, reg, val);
 }
 
 static void chipone_configure_pll(struct chipone *icn,
@@ -591,6 +662,11 @@ static int chipone_dsi_probe(struct mipi_dsi_device *dsi)
 	if (ret)
 		return ret;
 
+	icn->regmap = devm_regmap_init(dev, &chipone_dsi_regmap_bus,
+				       dsi, &chipone_regmap_config);
+	if (IS_ERR(icn->regmap))
+		return PTR_ERR(icn->regmap);
+
 	icn->interface_i2c = false;
 	icn->dsi = dsi;
 
@@ -616,6 +692,10 @@ static int chipone_i2c_probe(struct i2c_client *client,
 	if (ret)
 		return ret;
 
+	icn->regmap = devm_regmap_init_i2c(client, &chipone_regmap_config);
+	if (IS_ERR(icn->regmap))
+		return PTR_ERR(icn->regmap);
+
 	icn->interface_i2c = true;
 	icn->client = client;
 	dev_set_drvdata(dev, icn);