[RFT PATCH v2 2/3] hwmon: (spd5118) Use spd5118 specific read/write operations

[Guenter Roeck <linux@roeck-us.net>]

regmap write operations on i801 controllers were observed to fail with
-ENXIO errors. It appears that the i801 controller and/or at least some
spd5118 compatible chips do not support the I2C_FUNC_SMBUS_I2C_BLOCK
operation used by the regmap-i2c core if I2C_FUNC_SMBUS_I2C_BLOCK is
supported by the I2C/SMBus controller.

Stop using the regmap-i2c core and always use basic SMBus operations
instead.

Reported-by: Paul Menzel <pmenzel@molgen.mpg.de>
Closes: https://lore.kernel.org/linux-hwmon/33f369c1-1098-458e-9398-30037bd8c5aa@molgen.mpg.de/
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
v2: Added patch

 drivers/hwmon/Kconfig   |  2 +-
 drivers/hwmon/spd5118.c | 28 +++++++++++++++++++++++++++-
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index d5eced417fc3..fdfa778a965d 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -2184,7 +2184,7 @@ config SENSORS_INA3221
 config SENSORS_SPD5118
 	tristate "SPD5118 Compliant Temperature Sensors"
 	depends on I2C
-	select REGMAP_I2C
+	select REGMAP
 	help
 	  If you say yes here you get support for SPD5118 (JEDEC JESD300)
 	  compliant temperature sensors. Such sensors are found on DDR5 memory
diff --git a/drivers/hwmon/spd5118.c b/drivers/hwmon/spd5118.c
index d405c5ef755d..995c45e2a997 100644
--- a/drivers/hwmon/spd5118.c
+++ b/drivers/hwmon/spd5118.c
@@ -489,6 +489,31 @@ static bool spd5118_volatile_reg(struct device *dev, unsigned int reg)
 	}
 }
 
+static int spd5118_regmap_reg_read(void *context, unsigned int reg,
+				   unsigned int *val)
+{
+	int ret;
+
+	ret = i2c_smbus_read_byte_data(context, reg);
+	if (ret < 0)
+		return ret;
+
+	*val = ret;
+
+	return 0;
+}
+
+static int spd5118_regmap_reg_write(void *context, unsigned int reg,
+				    unsigned int val)
+{
+	return i2c_smbus_write_byte_data(context, reg, val);
+}
+
+static const struct regmap_bus spd5118_regmap_bus = {
+	.reg_write = spd5118_regmap_reg_write,
+	.reg_read = spd5118_regmap_reg_read,
+};
+
 static const struct regmap_range_cfg spd5118_regmap_range_cfg[] = {
 	{
 	.selector_reg   = SPD5118_REG_I2C_LEGACY_MODE,
@@ -526,7 +551,8 @@ static int spd5118_probe(struct i2c_client *client)
 	if (!data)
 		return -ENOMEM;
 
-	regmap = devm_regmap_init_i2c(client, &spd5118_regmap_config);
+	regmap = devm_regmap_init(dev, &spd5118_regmap_bus, client,
+				  &spd5118_regmap_config);
 	if (IS_ERR(regmap))
 		return dev_err_probe(dev, PTR_ERR(regmap), "regmap init failed\n");
 
-- 
2.39.2