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From: Min Li <lnimi@hotmail.com>
To: lee@kernel.org
Cc: linux-kernel@vger.kernel.org,
	Min Li <min.li.xe@renesas.com>
Subject: [PATCH mfd v1 1/2] mfd: rsmu: support I2C SMBus access
Date: Wed,  3 Apr 2024 14:24:35 -0400
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From: Min Li <min.li.xe@renesas.com>

8a3400x device implements its own reg_read and reg_write,
which only supports I2C bus access. This patch adds support
for SMBus access.

Signed-off-by: Min Li <min.li.xe@renesas.com>
---
 drivers/mfd/rsmu_i2c.c | 107 +++++++++++++++++++++++++++++++++++------
 drivers/mfd/rsmu_spi.c |   8 +--
 2 files changed, 97 insertions(+), 18 deletions(-)

diff --git a/drivers/mfd/rsmu_i2c.c b/drivers/mfd/rsmu_i2c.c
index 5711e512b..cba64f107 100644
--- a/drivers/mfd/rsmu_i2c.c
+++ b/drivers/mfd/rsmu_i2c.c
@@ -32,6 +32,8 @@
 #define	RSMU_SABRE_PAGE_ADDR		0x7F
 #define	RSMU_SABRE_PAGE_WINDOW		128
 
+typedef int (*rsmu_rw_device)(struct rsmu_ddata *rsmu, u8 reg, u8 *buf, u8 bytes);
+
 static const struct regmap_range_cfg rsmu_sabre_range_cfg[] = {
 	{
 		.range_min = 0,
@@ -54,7 +56,28 @@ static bool rsmu_sabre_volatile_reg(struct device *dev, unsigned int reg)
 	}
 }
 
-static int rsmu_read_device(struct rsmu_ddata *rsmu, u8 reg, u8 *buf, u16 bytes)
+static int rsmu_smbus_i2c_write_device(struct rsmu_ddata *rsmu, u8 reg, u8 *buf, u8 bytes)
+{
+	struct i2c_client *client = to_i2c_client(rsmu->dev);
+
+	return i2c_smbus_write_i2c_block_data(client, reg, bytes, buf);
+}
+
+static int rsmu_smbus_i2c_read_device(struct rsmu_ddata *rsmu, u8 reg, u8 *buf, u8 bytes)
+{
+	struct i2c_client *client = to_i2c_client(rsmu->dev);
+	int ret;
+
+	ret = i2c_smbus_read_i2c_block_data(client, reg, bytes, buf);
+	if (ret == bytes)
+		return 0;
+	else if (ret < 0)
+		return ret;
+	else
+		return -EIO;
+}
+
+static int rsmu_i2c_read_device(struct rsmu_ddata *rsmu, u8 reg, u8 *buf, u8 bytes)
 {
 	struct i2c_client *client = to_i2c_client(rsmu->dev);
 	struct i2c_msg msg[2];
@@ -84,10 +107,11 @@ static int rsmu_read_device(struct rsmu_ddata *rsmu, u8 reg, u8 *buf, u16 bytes)
 	return 0;
 }
 
-static int rsmu_write_device(struct rsmu_ddata *rsmu, u8 reg, u8 *buf, u16 bytes)
+static int rsmu_i2c_write_device(struct rsmu_ddata *rsmu, u8 reg, u8 *buf, u8 bytes)
 {
 	struct i2c_client *client = to_i2c_client(rsmu->dev);
-	u8 msg[RSMU_MAX_WRITE_COUNT + 1]; /* 1 Byte added for the device register */
+	/* we add 1 byte for device register */
+	u8 msg[RSMU_MAX_WRITE_COUNT + 1];
 	int cnt;
 
 	if (bytes > RSMU_MAX_WRITE_COUNT)
@@ -107,7 +131,8 @@ static int rsmu_write_device(struct rsmu_ddata *rsmu, u8 reg, u8 *buf, u16 bytes
 	return 0;
 }
 
-static int rsmu_write_page_register(struct rsmu_ddata *rsmu, u32 reg)
+static int rsmu_write_page_register(struct rsmu_ddata *rsmu, u32 reg,
+				    rsmu_rw_device rsmu_write_device)
 {
 	u32 page = reg & RSMU_CM_PAGE_MASK;
 	u8 buf[4];
@@ -136,35 +161,35 @@ static int rsmu_write_page_register(struct rsmu_ddata *rsmu, u32 reg)
 	return err;
 }
 
-static int rsmu_reg_read(void *context, unsigned int reg, unsigned int *val)
+static int rsmu_i2c_reg_read(void *context, unsigned int reg, unsigned int *val)
 {
 	struct rsmu_ddata *rsmu = i2c_get_clientdata((struct i2c_client *)context);
 	u8 addr = (u8)(reg & RSMU_CM_ADDRESS_MASK);
 	int err;
 
-	err = rsmu_write_page_register(rsmu, reg);
+	err = rsmu_write_page_register(rsmu, reg, rsmu_i2c_write_device);
 	if (err)
 		return err;
 
-	err = rsmu_read_device(rsmu, addr, (u8 *)val, 1);
+	err = rsmu_i2c_read_device(rsmu, addr, (u8 *)val, 1);
 	if (err)
 		dev_err(rsmu->dev, "Failed to read offset address 0x%x\n", addr);
 
 	return err;
 }
 
-static int rsmu_reg_write(void *context, unsigned int reg, unsigned int val)
+static int rsmu_i2c_reg_write(void *context, unsigned int reg, unsigned int val)
 {
 	struct rsmu_ddata *rsmu = i2c_get_clientdata((struct i2c_client *)context);
 	u8 addr = (u8)(reg & RSMU_CM_ADDRESS_MASK);
 	u8 data = (u8)val;
 	int err;
 
-	err = rsmu_write_page_register(rsmu, reg);
+	err = rsmu_write_page_register(rsmu, reg, rsmu_i2c_write_device);
 	if (err)
 		return err;
 
-	err = rsmu_write_device(rsmu, addr, &data, 1);
+	err = rsmu_i2c_write_device(rsmu, addr, &data, 1);
 	if (err)
 		dev_err(rsmu->dev,
 			"Failed to write offset address 0x%x\n", addr);
@@ -172,12 +197,57 @@ static int rsmu_reg_write(void *context, unsigned int reg, unsigned int val)
 	return err;
 }
 
-static const struct regmap_config rsmu_cm_regmap_config = {
+static int rsmu_smbus_i2c_reg_read(void *context, unsigned int reg, unsigned int *val)
+{
+	struct rsmu_ddata *rsmu = i2c_get_clientdata((struct i2c_client *)context);
+	u8 addr = (u8)(reg & RSMU_CM_ADDRESS_MASK);
+	int err;
+
+	err = rsmu_write_page_register(rsmu, reg, rsmu_smbus_i2c_write_device);
+	if (err)
+		return err;
+
+	err = rsmu_smbus_i2c_read_device(rsmu, addr, (u8 *)val, 1);
+	if (err)
+		dev_err(rsmu->dev, "Failed to read offset address 0x%x\n", addr);
+
+	return err;
+}
+
+static int rsmu_smbus_i2c_reg_write(void *context, unsigned int reg, unsigned int val)
+{
+	struct rsmu_ddata *rsmu = i2c_get_clientdata((struct i2c_client *)context);
+	u8 addr = (u8)(reg & RSMU_CM_ADDRESS_MASK);
+	u8 data = (u8)val;
+	int err;
+
+	err = rsmu_write_page_register(rsmu, reg, rsmu_smbus_i2c_write_device);
+	if (err)
+		return err;
+
+	err = rsmu_smbus_i2c_write_device(rsmu, addr, &data, 1);
+	if (err)
+		dev_err(rsmu->dev,
+			"Failed to write offset address 0x%x\n", addr);
+
+	return err;
+}
+
+static const struct regmap_config rsmu_i2c_cm_regmap_config = {
 	.reg_bits = 32,
 	.val_bits = 8,
 	.max_register = 0x20120000,
-	.reg_read = rsmu_reg_read,
-	.reg_write = rsmu_reg_write,
+	.reg_read = rsmu_i2c_reg_read,
+	.reg_write = rsmu_i2c_reg_write,
+	.cache_type = REGCACHE_NONE,
+};
+
+static const struct regmap_config rsmu_smbus_i2c_cm_regmap_config = {
+	.reg_bits = 32,
+	.val_bits = 8,
+	.max_register = 0x20120000,
+	.reg_read = rsmu_smbus_i2c_reg_read,
+	.reg_write = rsmu_smbus_i2c_reg_write,
 	.cache_type = REGCACHE_NONE,
 };
 
@@ -219,7 +289,15 @@ static int rsmu_i2c_probe(struct i2c_client *client)
 
 	switch (rsmu->type) {
 	case RSMU_CM:
-		cfg = &rsmu_cm_regmap_config;
+		if (i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
+			cfg = &rsmu_i2c_cm_regmap_config;
+		} else if (i2c_check_functionality(client->adapter,
+						   I2C_FUNC_SMBUS_I2C_BLOCK)) {
+			cfg = &rsmu_smbus_i2c_cm_regmap_config;
+		} else {
+			dev_err(rsmu->dev, "Unsupported i2c adapter\n");
+			return -ENOTSUPP;
+		}
 		break;
 	case RSMU_SABRE:
 		cfg = &rsmu_sabre_regmap_config;
@@ -236,6 +314,7 @@ static int rsmu_i2c_probe(struct i2c_client *client)
 		rsmu->regmap = devm_regmap_init(&client->dev, NULL, client, cfg);
 	else
 		rsmu->regmap = devm_regmap_init_i2c(client, cfg);
+
 	if (IS_ERR(rsmu->regmap)) {
 		ret = PTR_ERR(rsmu->regmap);
 		dev_err(rsmu->dev, "Failed to allocate register map: %d\n", ret);
diff --git a/drivers/mfd/rsmu_spi.c b/drivers/mfd/rsmu_spi.c
index ca0a1202c..39d9be1e1 100644
--- a/drivers/mfd/rsmu_spi.c
+++ b/drivers/mfd/rsmu_spi.c
@@ -106,10 +106,10 @@ static int rsmu_write_page_register(struct rsmu_ddata *rsmu, u32 reg)
 			return 0;
 		page_reg = RSMU_CM_PAGE_ADDR;
 		page = reg & RSMU_PAGE_MASK;
-		buf[0] = (u8)(page & 0xff);
-		buf[1] = (u8)((page >> 8) & 0xff);
-		buf[2] = (u8)((page >> 16) & 0xff);
-		buf[3] = (u8)((page >> 24) & 0xff);
+		buf[0] = (u8)(page & 0xFF);
+		buf[1] = (u8)((page >> 8) & 0xFF);
+		buf[2] = (u8)((page >> 16) & 0xFF);
+		buf[3] = (u8)((page >> 24) & 0xFF);
 		bytes = 4;
 		break;
 	case RSMU_SABRE:
-- 
2.39.2