From 5a6ecb27435ef7a67d7bec4543f0c6303f34e8a6 Mon Sep 17 00:00:00 2001
From: Jonas Jelonek <jelonek.jonas@gmail.com>
Date: Sat, 27 Sep 2025 10:19:23 +0000
Subject: [PATCH] i2c: rtl9300: use regmap fields and API for registers

Adapt the RTL9300 I2C controller driver to use more of the regmap
API, especially make use of reg_field and regmap_field instead of macros
to represent registers. Most register operations are performed through
regmap_field_* API then.

Handle SCL selection using separate chip-specific functions since this
is already known to differ between the Realtek SoC families in such a
way that this cannot be properly handled using just a different
reg_field.

This makes it easier to add support for newer generations or to handle
differences between specific revisions within a series. Just by
defining a separate driver data structure with the corresponding
register field definitions and linking it to a new compatible.

Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>
Tested-by: Sven Eckelmann <sven@narfation.org>
Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz> # On RTL9302C based board
Tested-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20250927101931.71575-2-jelonek.jonas@gmail.com

--- a/drivers/i2c/busses/i2c-rtl9300.c
+++ b/drivers/i2c/busses/i2c-rtl9300.c
@@ -23,97 +23,117 @@ struct rtl9300_i2c_chan {
 	u8 sda_pin;
 };
 
+enum rtl9300_i2c_reg_scope {
+	REG_SCOPE_GLOBAL,
+	REG_SCOPE_MASTER,
+};
+
+struct rtl9300_i2c_reg_field {
+	struct reg_field field;
+	enum rtl9300_i2c_reg_scope scope;
+};
+
+enum rtl9300_i2c_reg_fields {
+	F_DATA_WIDTH = 0,
+	F_DEV_ADDR,
+	F_I2C_FAIL,
+	F_I2C_TRIG,
+	F_MEM_ADDR,
+	F_MEM_ADDR_WIDTH,
+	F_RD_MODE,
+	F_RWOP,
+	F_SCL_FREQ,
+	F_SCL_SEL,
+	F_SDA_OUT_SEL,
+	F_SDA_SEL,
+
+	/* keep last */
+	F_NUM_FIELDS
+};
+
+struct rtl9300_i2c_drv_data {
+	struct rtl9300_i2c_reg_field field_desc[F_NUM_FIELDS];
+	int (*select_scl)(struct rtl9300_i2c *i2c, u8 scl);
+	u32 data_reg;
+	u8 max_nchan;
+};
+
 #define RTL9300_I2C_MUX_NCHAN	8
 
 struct rtl9300_i2c {
 	struct regmap *regmap;
 	struct device *dev;
 	struct rtl9300_i2c_chan chans[RTL9300_I2C_MUX_NCHAN];
+	struct regmap_field *fields[F_NUM_FIELDS];
 	u32 reg_base;
+	u32 data_reg;
 	u8 sda_pin;
 	struct mutex lock;
 };
 
 #define RTL9300_I2C_MST_CTRL1				0x0
-#define  RTL9300_I2C_MST_CTRL1_MEM_ADDR_OFS		8
-#define  RTL9300_I2C_MST_CTRL1_MEM_ADDR_MASK		GENMASK(31, 8)
-#define  RTL9300_I2C_MST_CTRL1_SDA_OUT_SEL_OFS		4
-#define  RTL9300_I2C_MST_CTRL1_SDA_OUT_SEL_MASK		GENMASK(6, 4)
-#define  RTL9300_I2C_MST_CTRL1_GPIO_SCL_SEL		BIT(3)
-#define  RTL9300_I2C_MST_CTRL1_RWOP			BIT(2)
-#define  RTL9300_I2C_MST_CTRL1_I2C_FAIL			BIT(1)
-#define  RTL9300_I2C_MST_CTRL1_I2C_TRIG			BIT(0)
 #define RTL9300_I2C_MST_CTRL2				0x4
-#define  RTL9300_I2C_MST_CTRL2_RD_MODE			BIT(15)
-#define  RTL9300_I2C_MST_CTRL2_DEV_ADDR_OFS		8
-#define  RTL9300_I2C_MST_CTRL2_DEV_ADDR_MASK		GENMASK(14, 8)
-#define  RTL9300_I2C_MST_CTRL2_DATA_WIDTH_OFS		4
-#define  RTL9300_I2C_MST_CTRL2_DATA_WIDTH_MASK		GENMASK(7, 4)
-#define  RTL9300_I2C_MST_CTRL2_MEM_ADDR_WIDTH_OFS	2
-#define  RTL9300_I2C_MST_CTRL2_MEM_ADDR_WIDTH_MASK	GENMASK(3, 2)
-#define  RTL9300_I2C_MST_CTRL2_SCL_FREQ_OFS		0
-#define  RTL9300_I2C_MST_CTRL2_SCL_FREQ_MASK		GENMASK(1, 0)
 #define RTL9300_I2C_MST_DATA_WORD0			0x8
 #define RTL9300_I2C_MST_DATA_WORD1			0xc
 #define RTL9300_I2C_MST_DATA_WORD2			0x10
 #define RTL9300_I2C_MST_DATA_WORD3			0x14
-
 #define RTL9300_I2C_MST_GLB_CTRL			0x384
 
 static int rtl9300_i2c_reg_addr_set(struct rtl9300_i2c *i2c, u32 reg, u16 len)
 {
-	u32 val, mask;
 	int ret;
 
-	val = len << RTL9300_I2C_MST_CTRL2_MEM_ADDR_WIDTH_OFS;
-	mask = RTL9300_I2C_MST_CTRL2_MEM_ADDR_WIDTH_MASK;
-
-	ret = regmap_update_bits(i2c->regmap, i2c->reg_base + RTL9300_I2C_MST_CTRL2, mask, val);
+	ret = regmap_field_write(i2c->fields[F_MEM_ADDR_WIDTH], len);
 	if (ret)
 		return ret;
 
-	val = reg << RTL9300_I2C_MST_CTRL1_MEM_ADDR_OFS;
-	mask = RTL9300_I2C_MST_CTRL1_MEM_ADDR_MASK;
+	return regmap_field_write(i2c->fields[F_MEM_ADDR], reg);
+}
 
-	return regmap_update_bits(i2c->regmap, i2c->reg_base + RTL9300_I2C_MST_CTRL1, mask, val);
+static int rtl9300_i2c_select_scl(struct rtl9300_i2c *i2c, u8 scl)
+{
+	return regmap_field_write(i2c->fields[F_SCL_SEL], 1);
 }
 
 static int rtl9300_i2c_config_io(struct rtl9300_i2c *i2c, u8 sda_pin)
 {
+	struct rtl9300_i2c_drv_data *drv_data;
 	int ret;
-	u32 val, mask;
 
-	ret = regmap_update_bits(i2c->regmap, RTL9300_I2C_MST_GLB_CTRL, BIT(sda_pin), BIT(sda_pin));
+	drv_data = (struct rtl9300_i2c_drv_data *)device_get_match_data(i2c->dev);
+
+	ret = regmap_field_update_bits(i2c->fields[F_SDA_SEL], BIT(sda_pin), BIT(sda_pin));
 	if (ret)
 		return ret;
 
-	val = (sda_pin << RTL9300_I2C_MST_CTRL1_SDA_OUT_SEL_OFS) |
-		RTL9300_I2C_MST_CTRL1_GPIO_SCL_SEL;
-	mask = RTL9300_I2C_MST_CTRL1_SDA_OUT_SEL_MASK | RTL9300_I2C_MST_CTRL1_GPIO_SCL_SEL;
+	ret = regmap_field_write(i2c->fields[F_SDA_OUT_SEL], sda_pin);
+	if (ret)
+		return ret;
 
-	return regmap_update_bits(i2c->regmap, i2c->reg_base + RTL9300_I2C_MST_CTRL1, mask, val);
+	return drv_data->select_scl(i2c, 0);
 }
 
 static int rtl9300_i2c_config_xfer(struct rtl9300_i2c *i2c, struct rtl9300_i2c_chan *chan,
 				   u16 addr, u16 len)
 {
-	u32 val, mask;
+	int ret;
 
 	if (len < 1 || len > 16)
 		return -EINVAL;
 
-	val = chan->bus_freq << RTL9300_I2C_MST_CTRL2_SCL_FREQ_OFS;
-	mask = RTL9300_I2C_MST_CTRL2_SCL_FREQ_MASK;
-
-	val |= addr << RTL9300_I2C_MST_CTRL2_DEV_ADDR_OFS;
-	mask |= RTL9300_I2C_MST_CTRL2_DEV_ADDR_MASK;
+	ret = regmap_field_write(i2c->fields[F_SCL_FREQ], chan->bus_freq);
+	if (ret)
+		return ret;
 
-	val |= ((len - 1) & 0xf) << RTL9300_I2C_MST_CTRL2_DATA_WIDTH_OFS;
-	mask |= RTL9300_I2C_MST_CTRL2_DATA_WIDTH_MASK;
+	ret = regmap_field_write(i2c->fields[F_DEV_ADDR], addr);
+	if (ret)
+		return ret;
 
-	mask |= RTL9300_I2C_MST_CTRL2_RD_MODE;
+	ret = regmap_field_write(i2c->fields[F_DATA_WIDTH], (len - 1) & 0xf);
+	if (ret)
+		return ret;
 
-	return regmap_update_bits(i2c->regmap, i2c->reg_base + RTL9300_I2C_MST_CTRL2, mask, val);
+	return regmap_field_write(i2c->fields[F_RD_MODE], 0);
 }
 
 static int rtl9300_i2c_read(struct rtl9300_i2c *i2c, u8 *buf, int len)
@@ -124,8 +144,7 @@ static int rtl9300_i2c_read(struct rtl93
 	if (len > 16)
 		return -EIO;
 
-	ret = regmap_bulk_read(i2c->regmap, i2c->reg_base + RTL9300_I2C_MST_DATA_WORD0,
-			       vals, ARRAY_SIZE(vals));
+	ret = regmap_bulk_read(i2c->regmap, i2c->data_reg, vals, ARRAY_SIZE(vals));
 	if (ret)
 		return ret;
 
@@ -152,52 +171,49 @@ static int rtl9300_i2c_write(struct rtl9
 		vals[reg] |= buf[i] << shift;
 	}
 
-	return regmap_bulk_write(i2c->regmap, i2c->reg_base + RTL9300_I2C_MST_DATA_WORD0,
-				vals, ARRAY_SIZE(vals));
+	return regmap_bulk_write(i2c->regmap, i2c->data_reg, vals, ARRAY_SIZE(vals));
 }
 
 static int rtl9300_i2c_writel(struct rtl9300_i2c *i2c, u32 data)
 {
-	return regmap_write(i2c->regmap, i2c->reg_base + RTL9300_I2C_MST_DATA_WORD0, data);
+	return regmap_write(i2c->regmap, i2c->data_reg, data);
 }
 
 static int rtl9300_i2c_execute_xfer(struct rtl9300_i2c *i2c, char read_write,
 				    int size, union i2c_smbus_data *data, int len)
 {
-	u32 val, mask;
+	u32 val;
 	int ret;
 
-	val = read_write == I2C_SMBUS_WRITE ? RTL9300_I2C_MST_CTRL1_RWOP : 0;
-	mask = RTL9300_I2C_MST_CTRL1_RWOP;
-
-	val |= RTL9300_I2C_MST_CTRL1_I2C_TRIG;
-	mask |= RTL9300_I2C_MST_CTRL1_I2C_TRIG;
+	ret = regmap_field_write(i2c->fields[F_RWOP], read_write == I2C_SMBUS_WRITE);
+	if (ret)
+		return ret;
 
-	ret = regmap_update_bits(i2c->regmap, i2c->reg_base + RTL9300_I2C_MST_CTRL1, mask, val);
+	ret = regmap_field_write(i2c->fields[F_I2C_TRIG], 1);
 	if (ret)
 		return ret;
 
-	ret = regmap_read_poll_timeout(i2c->regmap, i2c->reg_base + RTL9300_I2C_MST_CTRL1,
-				       val, !(val & RTL9300_I2C_MST_CTRL1_I2C_TRIG), 100, 100000);
+	ret = regmap_field_read_poll_timeout(i2c->fields[F_I2C_TRIG], val, !val, 100, 100000);
 	if (ret)
 		return ret;
 
-	if (val & RTL9300_I2C_MST_CTRL1_I2C_FAIL)
+	ret = regmap_field_read(i2c->fields[F_I2C_FAIL], &val);
+	if (ret)
+		return ret;
+	if (val)
 		return -EIO;
 
 	if (read_write == I2C_SMBUS_READ) {
 		switch (size) {
 		case I2C_SMBUS_BYTE:
 		case I2C_SMBUS_BYTE_DATA:
-			ret = regmap_read(i2c->regmap,
-					  i2c->reg_base + RTL9300_I2C_MST_DATA_WORD0, &val);
+			ret = regmap_read(i2c->regmap, i2c->data_reg, &val);
 			if (ret)
 				return ret;
 			data->byte = val & 0xff;
 			break;
 		case I2C_SMBUS_WORD_DATA:
-			ret = regmap_read(i2c->regmap,
-					  i2c->reg_base + RTL9300_I2C_MST_DATA_WORD0, &val);
+			ret = regmap_read(i2c->regmap, i2c->data_reg, &val);
 			if (ret)
 				return ret;
 			data->word = val & 0xffff;
@@ -355,9 +371,11 @@ static int rtl9300_i2c_probe(struct plat
 {
 	struct device *dev = &pdev->dev;
 	struct rtl9300_i2c *i2c;
+	struct fwnode_handle *child;
+	struct rtl9300_i2c_drv_data *drv_data;
+	struct reg_field fields[F_NUM_FIELDS];
 	u32 clock_freq, sda_pin;
 	int ret, i = 0;
-	struct fwnode_handle *child;
 
 	i2c = devm_kzalloc(dev, sizeof(*i2c), GFP_KERNEL);
 	if (!i2c)
@@ -376,9 +394,22 @@ static int rtl9300_i2c_probe(struct plat
 
 	platform_set_drvdata(pdev, i2c);
 
-	if (device_get_child_node_count(dev) > RTL9300_I2C_MUX_NCHAN)
+	drv_data = (struct rtl9300_i2c_drv_data *)device_get_match_data(i2c->dev);
+	if (device_get_child_node_count(dev) > drv_data->max_nchan)
 		return dev_err_probe(dev, -EINVAL, "Too many channels\n");
 
+	i2c->data_reg = i2c->reg_base + drv_data->data_reg;
+	for (i = 0; i < F_NUM_FIELDS; i++) {
+		fields[i] = drv_data->field_desc[i].field;
+		if (drv_data->field_desc[i].scope == REG_SCOPE_MASTER)
+			fields[i].reg += i2c->reg_base;
+	}
+	ret = devm_regmap_field_bulk_alloc(dev, i2c->regmap, i2c->fields,
+					   fields, F_NUM_FIELDS);
+	if (ret)
+		return ret;
+
+	i = 0;
 	device_for_each_child_node(dev, child) {
 		struct rtl9300_i2c_chan *chan = &i2c->chans[i];
 		struct i2c_adapter *adap = &chan->adap;
@@ -395,7 +426,6 @@ static int rtl9300_i2c_probe(struct plat
 		case I2C_MAX_STANDARD_MODE_FREQ:
 			chan->bus_freq = RTL9300_I2C_STD_FREQ;
 			break;
-
 		case I2C_MAX_FAST_MODE_FREQ:
 			chan->bus_freq = RTL9300_I2C_FAST_FREQ;
 			break;
@@ -427,11 +457,37 @@ static int rtl9300_i2c_probe(struct plat
 	return 0;
 }
 
+#define GLB_REG_FIELD(reg, msb, lsb)    \
+	{ .field = REG_FIELD(reg, msb, lsb), .scope = REG_SCOPE_GLOBAL }
+#define MST_REG_FIELD(reg, msb, lsb)    \
+	{ .field = REG_FIELD(reg, msb, lsb), .scope = REG_SCOPE_MASTER }
+
+static const struct rtl9300_i2c_drv_data rtl9300_i2c_drv_data = {
+	.field_desc = {
+		[F_MEM_ADDR]		= MST_REG_FIELD(RTL9300_I2C_MST_CTRL1, 8, 31),
+		[F_SDA_OUT_SEL]		= MST_REG_FIELD(RTL9300_I2C_MST_CTRL1, 4, 6),
+		[F_SCL_SEL]		= MST_REG_FIELD(RTL9300_I2C_MST_CTRL1, 3, 3),
+		[F_RWOP]		= MST_REG_FIELD(RTL9300_I2C_MST_CTRL1, 2, 2),
+		[F_I2C_FAIL]		= MST_REG_FIELD(RTL9300_I2C_MST_CTRL1, 1, 1),
+		[F_I2C_TRIG]		= MST_REG_FIELD(RTL9300_I2C_MST_CTRL1, 0, 0),
+		[F_RD_MODE]		= MST_REG_FIELD(RTL9300_I2C_MST_CTRL2, 15, 15),
+		[F_DEV_ADDR]		= MST_REG_FIELD(RTL9300_I2C_MST_CTRL2, 8, 14),
+		[F_DATA_WIDTH]		= MST_REG_FIELD(RTL9300_I2C_MST_CTRL2, 4, 7),
+		[F_MEM_ADDR_WIDTH]	= MST_REG_FIELD(RTL9300_I2C_MST_CTRL2, 2, 3),
+		[F_SCL_FREQ]		= MST_REG_FIELD(RTL9300_I2C_MST_CTRL2, 0, 1),
+		[F_SDA_SEL]		= GLB_REG_FIELD(RTL9300_I2C_MST_GLB_CTRL, 0, 7),
+	},
+	.select_scl = rtl9300_i2c_select_scl,
+	.data_reg = RTL9300_I2C_MST_DATA_WORD0,
+	.max_nchan = RTL9300_I2C_MUX_NCHAN,
+};
+
+
 static const struct of_device_id i2c_rtl9300_dt_ids[] = {
-	{ .compatible = "realtek,rtl9301-i2c" },
-	{ .compatible = "realtek,rtl9302b-i2c" },
-	{ .compatible = "realtek,rtl9302c-i2c" },
-	{ .compatible = "realtek,rtl9303-i2c" },
+	{ .compatible = "realtek,rtl9301-i2c", .data = (void *) &rtl9300_i2c_drv_data },
+	{ .compatible = "realtek,rtl9302b-i2c", .data = (void *) &rtl9300_i2c_drv_data },
+	{ .compatible = "realtek,rtl9302c-i2c", .data = (void *) &rtl9300_i2c_drv_data },
+	{ .compatible = "realtek,rtl9303-i2c", .data = (void *) &rtl9300_i2c_drv_data },
 	{}
 };
 MODULE_DEVICE_TABLE(of, i2c_rtl9300_dt_ids);
