2024-06-07 09:08:33

by Noah Wang

[permalink] [raw]
Subject: [PATCH 4/4] hwmon: add MP9941 driver

Add support for MPS step-down converter mp9941. This driver exposes
telemetry and limit value readings and writtings.

Signed-off-by: Noah Wang <[email protected]>
---
Documentation/hwmon/index.rst | 1 +
Documentation/hwmon/mp9941.rst | 92 +++++++++
MAINTAINERS | 7 +
drivers/hwmon/pmbus/Kconfig | 9 +
drivers/hwmon/pmbus/Makefile | 1 +
drivers/hwmon/pmbus/mp9941.c | 328 +++++++++++++++++++++++++++++++++
6 files changed, 438 insertions(+)
create mode 100644 Documentation/hwmon/mp9941.rst
create mode 100644 drivers/hwmon/pmbus/mp9941.c

diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index 9d9d55b889f2..9ff8149d9a9d 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -169,6 +169,7 @@ Hardware Monitoring Kernel Drivers
mp2993
mp5023
mp5990
+ mp9941
mpq8785
nct6683
nct6775
diff --git a/Documentation/hwmon/mp9941.rst b/Documentation/hwmon/mp9941.rst
new file mode 100644
index 000000000000..1274fa20e256
--- /dev/null
+++ b/Documentation/hwmon/mp9941.rst
@@ -0,0 +1,92 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver mp9941
+====================
+
+Supported chips:
+
+ * MPS mp9941
+
+ Prefix: 'mp9941'
+
+ * Datasheet
+ https://scnbwymvp-my.sharepoint.com/:f:/g/personal/admin_scnbwy_com/Eth4kX1_J1hMsaASHiOYL4QBHU5a75r-tRfLKbHnJFdKLQ?e=vxj3DF
+
+Author:
+
+ Noah Wang <[email protected]>
+
+Description
+-----------
+
+This driver implements support for Monolithic Power Systems, Inc. (MPS)
+MP9941 digital step-down converter.
+
+Device compliant with:
+
+- PMBus rev 1.3 interface.
+
+The driver exports the following attributes via the 'sysfs' files
+for input voltage:
+
+**in1_input**
+
+**in1_label**
+
+**in1_crit**
+
+**in1_crit_alarm**
+
+The driver provides the following attributes for output voltage:
+
+**in2_input**
+
+**in2_label**
+
+**in2_lcrit**
+
+**in2_lcrit_alarm**
+
+**in2_rated_max**
+
+**in2_rated_min**
+
+The driver provides the following attributes for input current:
+
+**curr1_input**
+
+**curr1_label**
+
+**curr1_max**
+
+**curr1_max_alarm**
+
+The driver provides the following attributes for output current:
+
+**curr2_input**
+
+**curr2_label**
+
+The driver provides the following attributes for input power:
+
+**power1_input**
+
+**power1_label**
+
+The driver provides the following attributes for output power:
+
+**power2_input**
+
+**power2_label**
+
+The driver provides the following attributes for temperature:
+
+**temp1_input**
+
+**temp1_crit**
+
+**temp1_crit_alarm**
+
+**temp1_max**
+
+**temp1_max_alarm**
diff --git a/MAINTAINERS b/MAINTAINERS
index f47f3e13b004..d4600533a3ee 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15265,6 +15265,13 @@ F: drivers/video/backlight/mp3309c.c
+F: Documentation/hwmon/mp2993.rst
+F: drivers/hwmon/pmbus/mp2993.c

++MPS MP9941 DRIVER
++M: Noah Wang <[email protected]>
++L: [email protected]
++S: Maintained
++F: Documentation/hwmon/mp9941.rst
++F: drivers/hwmon/pmbus/mp9941.c
+
MR800 AVERMEDIA USB FM RADIO DRIVER
M: Alexey Klimov <[email protected]>
L: [email protected]
diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
index d875d31ce84c..7d32cfc19820 100644
--- a/drivers/hwmon/pmbus/Kconfig
+++ b/drivers/hwmon/pmbus/Kconfig
@@ -380,6 +380,15 @@ config SENSORS_MP5990
This driver can also be built as a module. If so, the module will
be called mp5990.

+config SENSORS_MP9941
+ tristate "MPS MP9941"
+ help
+ If you say yes here you get hardware monitoring support for MPS
+ MP9941.
+
+ This driver can also be built as a module. If so, the module will
+ be called mp9941.
+
config SENSORS_MPQ7932_REGULATOR
bool "Regulator support for MPQ7932"
depends on SENSORS_MPQ7932 && REGULATOR
diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
index 312d3f0c0540..6c7177fde355 100644
--- a/drivers/hwmon/pmbus/Makefile
+++ b/drivers/hwmon/pmbus/Makefile
@@ -40,6 +40,7 @@ obj-$(CONFIG_SENSORS_MP2975) += mp2975.o
obj-$(CONFIG_SENSORS_MP2993) += mp2993.o
obj-$(CONFIG_SENSORS_MP5023) += mp5023.o
obj-$(CONFIG_SENSORS_MP5990) += mp5990.o
+obj-$(CONFIG_SENSORS_MP9941) += mp9941.o
obj-$(CONFIG_SENSORS_MPQ7932) += mpq7932.o
obj-$(CONFIG_SENSORS_MPQ8785) += mpq8785.o
obj-$(CONFIG_SENSORS_PLI1209BC) += pli1209bc.o
diff --git a/drivers/hwmon/pmbus/mp9941.c b/drivers/hwmon/pmbus/mp9941.c
new file mode 100644
index 000000000000..d24e98671e16
--- /dev/null
+++ b/drivers/hwmon/pmbus/mp9941.c
@@ -0,0 +1,328 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Hardware monitoring driver for MPS Multi-phase Digital VR Controllers(MP9941)
+ */
+
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include "pmbus.h"
+
+/*
+ * Vender specific registers. The MFR_ICC_MAX(0x02) is used to
+ * config the iin scale. The MFR_RESO_SET(0xC7) is used to
+ * config the vout format. The MFR_VR_MULTI_CONFIG_R1(0x0D) is
+ * used to identify the vout vid step.
+ */
+#define MFR_ICC_MAX 0x02
+#define MFR_RESO_SET 0xC7
+#define MFR_VR_MULTI_CONFIG_R1 0x0D
+
+#define MP9941_VIN_LIMIT_UINT 1
+#define MP9941_VIN_LIMIT_DIV 8
+#define MP9941_READ_VIN_UINT 1
+#define MP9941_READ_VIN_DIV 32
+
+#define MP9941_PAGE_NUM 1
+
+#define MP9941_RAIL1_FUNC (PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | \
+ PMBUS_HAVE_IOUT | PMBUS_HAVE_POUT | \
+ PMBUS_HAVE_TEMP | PMBUS_HAVE_PIN | \
+ PMBUS_HAVE_IIN | \
+ PMBUS_HAVE_STATUS_VOUT | \
+ PMBUS_HAVE_STATUS_IOUT | \
+ PMBUS_HAVE_STATUS_TEMP | \
+ PMBUS_HAVE_STATUS_INPUT)
+
+struct mp9941_data {
+ struct pmbus_driver_info info;
+ int vid_resolution;
+};
+
+#define to_mp9941_data(x) container_of(x, struct mp9941_data, info)
+
+static int mp2993_set_vout_format(struct i2c_client *client)
+{
+ int ret;
+
+ ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 0);
+ if (ret < 0)
+ return ret;
+
+ ret = i2c_smbus_read_word_data(client, MFR_RESO_SET);
+ if (ret < 0)
+ return ret;
+
+ /*
+ * page = 0, MFR_RESO_SET[7:6] defines the vout format
+ * 2'b11 set the vout format as direct
+ */
+ ret = (ret & ~GENMASK(7, 6)) | FIELD_PREP(GENMASK(7, 6), 3);
+
+ ret = i2c_smbus_write_word_data(client, MFR_RESO_SET, ret);
+ if (ret < 0)
+ return ret;
+
+ return 0;
+}
+
+static int
+mp2993_identify_vid_resolution(struct i2c_client *client, struct pmbus_driver_info *info)
+{
+ struct mp9941_data *data = to_mp9941_data(info);
+ int ret;
+
+ /*
+ * page = 2, MFR_VR_MULTI_CONFIG_R1[4:4] defines rail1 vid step value
+ * 1'b0 represents the vid step value is 10mV
+ * 1'b1 represents the vid step value is 5mV
+ */
+ ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 2);
+ if (ret < 0)
+ return ret;
+
+ ret = i2c_smbus_read_word_data(client, MFR_VR_MULTI_CONFIG_R1);
+ if (ret < 0)
+ return ret;
+
+ if (FIELD_GET(GENMASK(4, 4), ret))
+ data->vid_resolution = 5;
+ else
+ data->vid_resolution = 10;
+
+ return 0;
+}
+
+static int mp9941_identify_iin_scale(struct i2c_client *client)
+{
+ int ret;
+
+ ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 0);
+ if (ret < 0)
+ return ret;
+
+ ret = i2c_smbus_read_word_data(client, MFR_RESO_SET);
+ if (ret < 0)
+ return ret;
+
+ ret = (ret & ~GENMASK(3, 2)) | FIELD_PREP(GENMASK(3, 2), 0);
+
+ ret = i2c_smbus_write_word_data(client, MFR_RESO_SET, ret);
+ if (ret < 0)
+ return ret;
+
+ /*
+ * page = 2, MFR_ICC_MAX[15:13] defines the iin scale
+ * 3'b000 set the iout scale as 0.5A/Lsb
+ */
+ ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 2);
+ if (ret < 0)
+ return ret;
+
+ ret = i2c_smbus_read_word_data(client, MFR_ICC_MAX);
+ if (ret < 0)
+ return ret;
+
+ ret = (ret & ~GENMASK(15, 13)) | FIELD_PREP(GENMASK(15, 13), 0);
+ ret = i2c_smbus_write_word_data(client, MFR_ICC_MAX, ret);
+ if (ret < 0)
+ return ret;
+
+ return 0;
+}
+
+static int mp9941_identify(struct i2c_client *client, struct pmbus_driver_info *info)
+{
+ int ret;
+
+ ret = mp9941_identify_iin_scale(client);
+ if (ret < 0)
+ return ret;
+
+ ret = mp2993_identify_vid_resolution(client, info);
+ if (ret < 0)
+ return ret;
+
+ ret = mp2993_set_vout_format(client);
+ if (ret < 0)
+ return ret;
+
+ return ret;
+}
+
+static int mp9941_read_word_data(struct i2c_client *client, int page, int phase,
+ int reg)
+{
+ const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
+ struct mp9941_data *data = to_mp9941_data(info);
+ int ret;
+
+ switch (reg) {
+ case PMBUS_READ_VIN:
+ /* The MP9941 vin scale is (1/32V)/Lsb */
+ ret = pmbus_read_word_data(client, page, phase, reg);
+ if (ret < 0)
+ return ret;
+
+ ret = DIV_ROUND_CLOSEST((ret & GENMASK(9, 0)) * MP9941_READ_VIN_UINT,
+ MP9941_READ_VIN_DIV);
+ break;
+ case PMBUS_READ_IIN:
+ ret = pmbus_read_word_data(client, page, phase, reg);
+ if (ret < 0)
+ return ret;
+
+ ret = ret & GENMASK(10, 0);
+ break;
+ case PMBUS_VIN_OV_FAULT_LIMIT:
+ /* The MP9941 vin ov limit scale is (1/8V)/Lsb */
+ ret = pmbus_read_word_data(client, page, phase, reg);
+ if (ret < 0)
+ return ret;
+
+ ret = DIV_ROUND_CLOSEST((ret & GENMASK(7, 0)) * MP9941_VIN_LIMIT_UINT,
+ MP9941_VIN_LIMIT_DIV);
+ break;
+ case PMBUS_IIN_OC_WARN_LIMIT:
+ ret = pmbus_read_word_data(client, page, phase, reg);
+ if (ret < 0)
+ return ret;
+
+ ret = ret & GENMASK(7, 0);
+ break;
+ case PMBUS_VOUT_UV_FAULT_LIMIT:
+ case PMBUS_MFR_VOUT_MIN:
+ case PMBUS_MFR_VOUT_MAX:
+ /*
+ * The vout scale is set to 1mV/Lsb(using r/m/b scale).
+ * But the vout uv limit and vout max/min scale is 1VID/Lsb,
+ * so the vout uv limit and vout max/min value should be
+ * multiplied by vid resolution.
+ */
+ ret = pmbus_read_word_data(client, page, phase, reg);
+ if (ret < 0)
+ return ret;
+
+ ret = ret * data->vid_resolution;
+ break;
+ case PMBUS_READ_IOUT:
+ case PMBUS_READ_POUT:
+ case PMBUS_READ_TEMPERATURE_1:
+ case PMBUS_READ_VOUT:
+ case PMBUS_READ_PIN:
+ case PMBUS_OT_FAULT_LIMIT:
+ case PMBUS_OT_WARN_LIMIT:
+ ret = -ENODATA;
+ break;
+ default:
+ ret = -EINVAL;
+ break;
+ }
+
+ return ret;
+}
+
+static int mp9941_write_word_data(struct i2c_client *client, int page, int reg,
+ u16 word)
+{
+ const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
+ struct mp9941_data *data = to_mp9941_data(info);
+ int ret;
+
+ switch (reg) {
+ case PMBUS_VIN_OV_FAULT_LIMIT:
+ /* The MP9941 vin ov limit scale is (1/8V)/Lsb */
+ ret = pmbus_write_word_data(client, page, reg,
+ DIV_ROUND_CLOSEST(word * MP9941_VIN_LIMIT_DIV,
+ MP9941_VIN_LIMIT_UINT));
+ break;
+ case PMBUS_VOUT_UV_FAULT_LIMIT:
+ case PMBUS_MFR_VOUT_MIN:
+ case PMBUS_MFR_VOUT_MAX:
+ ret = pmbus_write_word_data(client, page, reg,
+ DIV_ROUND_CLOSEST(word, data->vid_resolution));
+ break;
+ case PMBUS_IIN_OC_WARN_LIMIT:
+ case PMBUS_OT_FAULT_LIMIT:
+ case PMBUS_OT_WARN_LIMIT:
+ ret = -ENODATA;
+ break;
+ default:
+ ret = -EINVAL;
+ break;
+ }
+
+ return ret;
+}
+
+static const struct pmbus_driver_info mp9941_info = {
+ .pages = MP9941_PAGE_NUM,
+ .format[PSC_VOLTAGE_IN] = direct,
+ .format[PSC_CURRENT_IN] = direct,
+ .format[PSC_CURRENT_OUT] = linear,
+ .format[PSC_POWER] = linear,
+ .format[PSC_TEMPERATURE] = direct,
+ .format[PSC_VOLTAGE_OUT] = direct,
+
+ .m[PSC_TEMPERATURE] = 1,
+ .R[PSC_TEMPERATURE] = 0,
+ .b[PSC_TEMPERATURE] = 0,
+
+ .m[PSC_VOLTAGE_IN] = 1,
+ .R[PSC_VOLTAGE_IN] = 0,
+ .b[PSC_VOLTAGE_IN] = 0,
+
+ .m[PSC_CURRENT_IN] = 2,
+ .R[PSC_CURRENT_IN] = 0,
+ .b[PSC_CURRENT_IN] = 0,
+
+ .m[PSC_VOLTAGE_OUT] = 1,
+ .R[PSC_VOLTAGE_OUT] = 3,
+ .b[PSC_VOLTAGE_OUT] = 0,
+
+ .func[0] = MP9941_RAIL1_FUNC,
+ .read_word_data = mp9941_read_word_data,
+ .write_word_data = mp9941_write_word_data,
+ .identify = mp9941_identify,
+};
+
+static int mp9941_probe(struct i2c_client *client)
+{
+ struct mp9941_data *data;
+
+ data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ memcpy(&data->info, &mp9941_info, sizeof(mp9941_info));
+
+ return pmbus_do_probe(client, &data->info);
+}
+
+static const struct i2c_device_id mp9941_id[] = {
+ {"mp9941", 0},
+ {}
+};
+MODULE_DEVICE_TABLE(i2c, mp9941_id);
+
+static const struct of_device_id __maybe_unused mp9941_of_match[] = {
+ {.compatible = "mps,mp9941"},
+ {}
+};
+MODULE_DEVICE_TABLE(of, mp9941_of_match);
+
+static struct i2c_driver mp9941_driver = {
+ .driver = {
+ .name = "mp9941",
+ .of_match_table = mp9941_of_match,
+ },
+ .probe = mp9941_probe,
+ .id_table = mp9941_id,
+};
+
+module_i2c_driver(mp9941_driver);
+
+MODULE_AUTHOR("Noah Wang <[email protected]>");
+MODULE_DESCRIPTION("PMBus driver for MPS MP9941");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS(PMBUS);
--
2.25.1



2024-06-10 16:18:21

by Guenter Roeck

[permalink] [raw]
Subject: Re: [PATCH 4/4] hwmon: add MP9941 driver

On 6/7/24 02:05, Noah Wang wrote:
> Add support for MPS step-down converter mp9941. This driver exposes
> telemetry and limit value readings and writtings.
>
> Signed-off-by: Noah Wang <[email protected]>
> ---
> Documentation/hwmon/index.rst | 1 +
> Documentation/hwmon/mp9941.rst | 92 +++++++++
> MAINTAINERS | 7 +
> drivers/hwmon/pmbus/Kconfig | 9 +
> drivers/hwmon/pmbus/Makefile | 1 +
> drivers/hwmon/pmbus/mp9941.c | 328 +++++++++++++++++++++++++++++++++
> 6 files changed, 438 insertions(+)
> create mode 100644 Documentation/hwmon/mp9941.rst
> create mode 100644 drivers/hwmon/pmbus/mp9941.c
>
> diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
> index 9d9d55b889f2..9ff8149d9a9d 100644
> --- a/Documentation/hwmon/index.rst
> +++ b/Documentation/hwmon/index.rst
> @@ -169,6 +169,7 @@ Hardware Monitoring Kernel Drivers
> mp2993
> mp5023
> mp5990
> + mp9941
> mpq8785
> nct6683
> nct6775
> diff --git a/Documentation/hwmon/mp9941.rst b/Documentation/hwmon/mp9941.rst
> new file mode 100644
> index 000000000000..1274fa20e256
> --- /dev/null
> +++ b/Documentation/hwmon/mp9941.rst
> @@ -0,0 +1,92 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +Kernel driver mp9941
> +====================
> +
> +Supported chips:
> +
> + * MPS mp9941
> +
> + Prefix: 'mp9941'
> +
> + * Datasheet
> + https://scnbwymvp-my.sharepoint.com/:f:/g/personal/admin_scnbwy_com/Eth4kX1_J1hMsaASHiOYL4QBHU5a75r-tRfLKbHnJFdKLQ?e=vxj3DF
> +
> +Author:
> +
> + Noah Wang <[email protected]>
> +
> +Description
> +-----------
> +
> +This driver implements support for Monolithic Power Systems, Inc. (MPS)
> +MP9941 digital step-down converter.
> +
> +Device compliant with:
> +
> +- PMBus rev 1.3 interface.
> +
> +The driver exports the following attributes via the 'sysfs' files
> +for input voltage:
> +
> +**in1_input**
> +
> +**in1_label**
> +
> +**in1_crit**
> +
> +**in1_crit_alarm**
> +
> +The driver provides the following attributes for output voltage:
> +
> +**in2_input**
> +
> +**in2_label**
> +
> +**in2_lcrit**
> +
> +**in2_lcrit_alarm**
> +
> +**in2_rated_max**
> +
> +**in2_rated_min**
> +
> +The driver provides the following attributes for input current:
> +
> +**curr1_input**
> +
> +**curr1_label**
> +
> +**curr1_max**
> +
> +**curr1_max_alarm**
> +
> +The driver provides the following attributes for output current:
> +
> +**curr2_input**
> +
> +**curr2_label**
> +
> +The driver provides the following attributes for input power:
> +
> +**power1_input**
> +
> +**power1_label**
> +
> +The driver provides the following attributes for output power:
> +
> +**power2_input**
> +
> +**power2_label**
> +
> +The driver provides the following attributes for temperature:
> +
> +**temp1_input**
> +
> +**temp1_crit**
> +
> +**temp1_crit_alarm**
> +
> +**temp1_max**
> +
> +**temp1_max_alarm**
> diff --git a/MAINTAINERS b/MAINTAINERS
> index f47f3e13b004..d4600533a3ee 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -15265,6 +15265,13 @@ F: drivers/video/backlight/mp3309c.c
> +F: Documentation/hwmon/mp2993.rst
> +F: drivers/hwmon/pmbus/mp2993.c
>
> ++MPS MP9941 DRIVER
> ++M: Noah Wang <[email protected]>
> ++L: [email protected]
> ++S: Maintained
> ++F: Documentation/hwmon/mp9941.rst
> ++F: drivers/hwmon/pmbus/mp9941.c
> +
> MR800 AVERMEDIA USB FM RADIO DRIVER
> M: Alexey Klimov <[email protected]>
> L: [email protected]
> diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
> index d875d31ce84c..7d32cfc19820 100644
> --- a/drivers/hwmon/pmbus/Kconfig
> +++ b/drivers/hwmon/pmbus/Kconfig
> @@ -380,6 +380,15 @@ config SENSORS_MP5990
> This driver can also be built as a module. If so, the module will
> be called mp5990.
>
> +config SENSORS_MP9941
> + tristate "MPS MP9941"
> + help
> + If you say yes here you get hardware monitoring support for MPS
> + MP9941.
> +
> + This driver can also be built as a module. If so, the module will
> + be called mp9941.
> +
> config SENSORS_MPQ7932_REGULATOR
> bool "Regulator support for MPQ7932"
> depends on SENSORS_MPQ7932 && REGULATOR
> diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
> index 312d3f0c0540..6c7177fde355 100644
> --- a/drivers/hwmon/pmbus/Makefile
> +++ b/drivers/hwmon/pmbus/Makefile
> @@ -40,6 +40,7 @@ obj-$(CONFIG_SENSORS_MP2975) += mp2975.o
> obj-$(CONFIG_SENSORS_MP2993) += mp2993.o
> obj-$(CONFIG_SENSORS_MP5023) += mp5023.o
> obj-$(CONFIG_SENSORS_MP5990) += mp5990.o
> +obj-$(CONFIG_SENSORS_MP9941) += mp9941.o
> obj-$(CONFIG_SENSORS_MPQ7932) += mpq7932.o
> obj-$(CONFIG_SENSORS_MPQ8785) += mpq8785.o
> obj-$(CONFIG_SENSORS_PLI1209BC) += pli1209bc.o
> diff --git a/drivers/hwmon/pmbus/mp9941.c b/drivers/hwmon/pmbus/mp9941.c
> new file mode 100644
> index 000000000000..d24e98671e16
> --- /dev/null
> +++ b/drivers/hwmon/pmbus/mp9941.c
> @@ -0,0 +1,328 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Hardware monitoring driver for MPS Multi-phase Digital VR Controllers(MP9941)
> + */
> +
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include "pmbus.h"
> +
> +/*
> + * Vender specific registers. The MFR_ICC_MAX(0x02) is used to
> + * config the iin scale. The MFR_RESO_SET(0xC7) is used to
> + * config the vout format. The MFR_VR_MULTI_CONFIG_R1(0x0D) is
> + * used to identify the vout vid step.
> + */
> +#define MFR_ICC_MAX 0x02
> +#define MFR_RESO_SET 0xC7
> +#define MFR_VR_MULTI_CONFIG_R1 0x0D
> +
> +#define MP9941_VIN_LIMIT_UINT 1
> +#define MP9941_VIN_LIMIT_DIV 8
> +#define MP9941_READ_VIN_UINT 1
> +#define MP9941_READ_VIN_DIV 32
> +
> +#define MP9941_PAGE_NUM 1
> +
> +#define MP9941_RAIL1_FUNC (PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | \
> + PMBUS_HAVE_IOUT | PMBUS_HAVE_POUT | \
> + PMBUS_HAVE_TEMP | PMBUS_HAVE_PIN | \
> + PMBUS_HAVE_IIN | \
> + PMBUS_HAVE_STATUS_VOUT | \
> + PMBUS_HAVE_STATUS_IOUT | \
> + PMBUS_HAVE_STATUS_TEMP | \
> + PMBUS_HAVE_STATUS_INPUT)
> +
> +struct mp9941_data {
> + struct pmbus_driver_info info;
> + int vid_resolution;
> +};
> +
> +#define to_mp9941_data(x) container_of(x, struct mp9941_data, info)
> +
> +static int mp2993_set_vout_format(struct i2c_client *client)
> +{
> + int ret;
> +
> + ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 0);
> + if (ret < 0)
> + return ret;
> +
> + ret = i2c_smbus_read_word_data(client, MFR_RESO_SET);
> + if (ret < 0)
> + return ret;
> +
> + /*
> + * page = 0, MFR_RESO_SET[7:6] defines the vout format
> + * 2'b11 set the vout format as direct
> + */
> + ret = (ret & ~GENMASK(7, 6)) | FIELD_PREP(GENMASK(7, 6), 3);
> +
> + ret = i2c_smbus_write_word_data(client, MFR_RESO_SET, ret);
> + if (ret < 0)
> + return ret;
> +

i2c_smbus_write_word_data() returns 0 or an error code. The above
is therefore not necessary.
return i2c_smbus_write_word_data(client, MFR_RESO_SET, ret);
is sufficient. Same everythere else where the same pattern is used.

Thanks,
Guenter