Re: [PATCH v2 3/3] hwmon: (fs1603) Add driver for TDK FS160x and FS1006 uPOL converters

[Guenter Roeck]

On Tue, Oct 20, 2026 at 04:48:16PM +0000, Kevin Jia wrote:
> The TDK FS1603, FS1604, FS1606 and FS1006 are uPOL DC-DC converters with
> an integrated inductor. They report input voltage, output voltage, output
> current and temperature, plus over-voltage, over-current and
> over-temperature status, over a proprietary I2C register map. They are
> not PMBus devices, and their register numbers collide with PMBus command
> codes: 0x21 is a status byte here where PMBus defines VOUT_COMMAND.
> 
> The parts have no ID register, and the FS1606-0600 and FS1606-2500
> presets change how telemetry is encoded: the -2500 uses the 20mV steps
> of the higher voltage parts, and the -0600 needs a current correction
> derived from the IOUT_GAIN register and the output voltage. The model is
> therefore taken from the device name or compatible. OCSet[2:0], the
> programmable over-current protection level, ships with a different
> default on each family member, so probe warns if it does not match the
> declared part, which usually catches a wrong device name.
> 
> The over-voltage and over-temperature protection thresholds are
> reported as in1_crit and temp1_crit. The over-voltage threshold is a
> percentage of the VOUT_SET target, so the driver reads VOUT_SET but
> never writes it: VOUT_SET is a two-byte pair, and a partial write leaves
> the part silently ignoring all register writes until its input power is
> cycled. The driver is read-only.
> 
> Power good is not exposed. It also deasserts while the output is
> disabled or soft-starting, so it would report a deliberately disabled
> output as a fault.
> 
> On boards that raise the rail with a feedback divider, VOUT_SET holds
> the feedback-pin target while the output voltage telemetry reports the
> rail. The driver measures the divider ratio at probe from the output
> voltage and the Fb register and scales the over-voltage threshold by
> it, so in1_crit is in the same domain as in1_input. A part whose Fb
> reads within four steps of the output keeps a ratio of one.
> 
> Co-developed-by: Abdurrahman Hussain <abdurrahman@xxxxxxxxxx>
> Signed-off-by: Abdurrahman Hussain <abdurrahman@xxxxxxxxxx>
> Signed-off-by: Kevin Jia <kjia@xxxxxxxxxx>
> ---
>  Documentation/hwmon/fs1603.rst |  78 ++++++
>  Documentation/hwmon/index.rst  |   1 +
>  MAINTAINERS                    |   7 +
>  drivers/hwmon/Kconfig          |  11 +
>  drivers/hwmon/Makefile         |   1 +
>  drivers/hwmon/fs1603.c         | 540 +++++++++++++++++++++++++++++++++++++++++
>  6 files changed, 638 insertions(+)
> 
> diff --git a/Documentation/hwmon/fs1603.rst b/Documentation/hwmon/fs1603.rst
> new file mode 100644
> index 000000000000..ba0038e0d9b5
> --- /dev/null
> +++ b/Documentation/hwmon/fs1603.rst
> @@ -0,0 +1,78 @@
> +.. SPDX-License-Identifier: GPL-2.0-or-later
> +
> +Kernel driver fs1603
> +====================
> +
> +Supported chips:
> +
> +  * TDK FS1603
> +
> +    Prefix: 'fs1603'
> +
> +    Datasheet: Publicly available at the TDK website
> +
> +  * TDK FS1604
> +
> +    Prefix: 'fs1604'
> +
> +    Datasheet: Publicly available at the TDK website
> +
> +  * TDK FS1606, FS1606-0600, FS1606-2500
> +
> +    Prefixes: 'fs1606', 'fs1606_0600', 'fs1606_2500'
> +
> +    Datasheet: Publicly available at the TDK website
> +
> +  * TDK FS1006-3300, FS1006-5000
> +
> +    Prefixes: 'fs1006_3300', 'fs1006_5000'
> +
> +    Datasheet: Publicly available at the TDK website
> +
> +Author:
> +
> +  * Kevin Jia <kjia@xxxxxxxxxx>
> +
> +Description
> +-----------
> +
> +The TDK FS160x and FS1006 are uPOL DC-DC converters with an integrated
> +inductor. They report input voltage, output voltage, output current and
> +temperature over a proprietary I2C register map. They are not PMBus devices,
> +and their register numbers collide with PMBus command codes, so a PMBus driver
> +must not be bound to them.
> +
> +The model is not auto-detected. It must be declared through the I2C device
> +name or the devicetree compatible. The FS1606-0600 and FS1606-2500 presets
> +scale telemetry differently from the base FS1606, so they must be declared
> +by their own names. At probe time the driver compares the OCSet register,
> +the programmable over-current protection level, with the factory default of
> +the declared family member and logs a warning on a mismatch. That usually
> +means the wrong model was declared, but it is expected on boards that
> +reprogram the over-current protection level.
> +
> +The driver is read-only. On boards that use a feedback divider to reach a
> +higher rail voltage, the output voltage is still reported for the rail, and the
> +over-voltage threshold is scaled to the rail by the divider ratio, measured at
> +probe from the output voltage and the feedback pin. TDK notes that current
> +reporting does not apply in that configuration.
> +
> +Sysfs attributes
> +----------------
> +
> +=================== == ========================================================
> +in0_input           RO Input voltage in millivolts.
> +in0_label           RO "vin"
> +in1_input           RO Output voltage in millivolts.
> +in1_label           RO "vout"
> +in1_crit            RO Output over-voltage protection threshold in millivolts:
> +                       the OV_Threshold percentage of the VOUT_SET target,
> +                       scaled to the rail on boards with a feedback divider.
> +in1_alarm           RO Output over-voltage status.
> +curr1_input         RO Output current in milliamperes.
> +curr1_alarm         RO Over-current status.
> +temp1_input         RO Temperature in millidegrees Celsius.
> +temp1_crit          RO Over-temperature protection threshold in millidegrees
> +                       Celsius.
> +temp1_alarm         RO Over-temperature status.
> +=================== == ========================================================
> diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
> index 199ca79621e9..7d79a7aadaa6 100644
> --- a/Documentation/hwmon/index.rst
> +++ b/Documentation/hwmon/index.rst
> @@ -81,6 +81,7 @@ Hardware Monitoring Kernel Drivers
>     f71805f
>     f71882fg
>     fam15h_power
> +   fs1603
>     fsp-3y
>     ftsteutates
>     g760a
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 5ad12c57ca5f..24073ee3ede2 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -26799,6 +26799,13 @@ W:	https://linuxtv.org
>  T:	git git://linuxtv.org/media.git
>  F:	drivers/media/i2c/tda9840*
>  
> +TDK FS1603 HARDWARE MONITOR DRIVER
> +M:	Kevin Jia <kjia@xxxxxxxxxx>
> +L:	linux-hwmon@xxxxxxxxxxxxxxx
> +S:	Maintained
> +F:	Documentation/hwmon/fs1603.rst
> +F:	drivers/hwmon/fs1603.c
> +
>  TEA5761 TUNER DRIVER
>  M:	Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
>  L:	linux-media@xxxxxxxxxxxxxxx
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 18c682e1a475..047a3050946b 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -728,6 +728,17 @@ config SENSORS_MC33XS2410
>  	  This driver can also be built as a module. If so, the module
>  	  will be called mc33xs2410_hwmon.
>  
> +config SENSORS_FS1603
> +	tristate "TDK FS1603 and compatible uPOL DC-DC converters"
> +	depends on I2C
> +	select REGMAP_I2C
> +	help
> +	  If you say yes here you get hardware monitoring support for the
> +	  TDK FS1603, FS1604, FS1606 and FS1006 uPOL DC-DC converters.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called fs1603.
> +
>  config SENSORS_FSCHMD
>  	tristate "Fujitsu Siemens Computers sensor chips"
>  	depends on (X86 || COMPILE_TEST) && I2C
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index d4c345ed7261..23a5f262eecf 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -85,6 +85,7 @@ obj-$(CONFIG_SENSORS_F71805F)	+= f71805f.o
>  obj-$(CONFIG_SENSORS_F71882FG)	+= f71882fg.o
>  obj-$(CONFIG_SENSORS_F75375S)	+= f75375s.o
>  obj-$(CONFIG_SENSORS_FAM15H_POWER) += fam15h_power.o
> +obj-$(CONFIG_SENSORS_FS1603)	+= fs1603.o
>  obj-$(CONFIG_SENSORS_FSCHMD)	+= fschmd.o
>  obj-$(CONFIG_SENSORS_FTSTEUTATES) += ftsteutates.o
>  obj-$(CONFIG_SENSORS_G760A)	+= g760a.o
> diff --git a/drivers/hwmon/fs1603.c b/drivers/hwmon/fs1603.c
> new file mode 100644
> index 000000000000..afe75657ce39
> --- /dev/null
> +++ b/drivers/hwmon/fs1603.c
> @@ -0,0 +1,540 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +
> +/*
> + * Copyright (C) 2026 Nexthop Systems Inc.
> + *
> + * Driver for the TDK FS160x family of uPOL DC-DC converters with integrated
> + * inductor. Supported models: FS1603, FS1604, FS1606, FS1006.
> + *
> + * The parts expose voltage, current and temperature telemetry over a
> + * proprietary I2C register map. They are not PMBus devices, and their
> + * register numbers actively collide with PMBus command codes -- 0x21 is a
> + * status byte here where PMBus defines VOUT_COMMAND -- so a generic PMBus
> + * driver must never be bound to them.
> + *
> + * Read-only. VOUT_SET (0x12/0x13) is an atomic write-protected pair: writing
> + * the high byte arms an update that takes effect only once the low byte is
> + * written. A partial write leaves the part armed, after which it acknowledges
> + * but silently ignores every register write until its input power is cycled,
> + * so this driver only reads it, to scale the over-voltage threshold.
> + *
> + * On a board that raises the rail with a feedback divider, VOUT still reports
> + * the rail but VOUT_SET holds the feedback-pin target, so the over-voltage
> + * threshold is scaled by the divider ratio, measured at probe from VOUT and
> + * the Fb register (0x22). TDK notes that current reporting does not apply in
> + * that configuration.
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/err.h>
> +#include <linux/hwmon.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +
> +#define FS1603_REG_PVIN			0x0C
> +#define FS1603_REG_VOUT			0x0D
> +#define FS1603_REG_IOUT			0x0E
> +#define FS1603_REG_TEMP			0x0F
> +#define FS1603_REG_VOUT_SET_HI		0x12
> +#define FS1603_REG_VOUT_SET_LO		0x13
> +#define FS1603_REG_OCSET		0x15
> +#define FS1603_REG_OV_THRESHOLD		0x17
> +#define FS1603_REG_OT_THRESHOLD		0x19
> +#define FS1603_REG_IOUT_GAIN		0x1A
> +#define FS1603_REG_STATUS		0x21
> +#define FS1603_REG_FB			0x22
> +
> +#define FS1603_VOUT_SET_HI_MASK		BIT(0)
> +#define FS1603_OV_THRESHOLD_MASK	GENMASK(1, 0)
> +#define FS1603_OT_THRESHOLD_MASK	GENMASK(1, 0)
> +#define FS1603_IOUT_GAIN_MASK		GENMASK(7, 2)
> +
> +/*
> + * OCSet[2:0] is the user-programmable over-current protection trip level,
> + * not an ID. Each family member ships with a different default, so a
> + * mismatch at probe usually means the wrong model was declared.
> + */
> +#define FS1603_OCSET_LEVEL		GENMASK(2, 0)
> +#define FS1603_OCSET_DEFAULT_FS1603	0
> +#define FS1603_OCSET_DEFAULT_FS1604	1
> +#define FS1603_OCSET_DEFAULT_FS1606	2
> +#define FS1603_OCSET_DEFAULT_FS1006	3
> +
> +/* Bits in FS1603_REG_STATUS. */
> +#define FS1603_STATUS_OVER_VOLTAGE	BIT(6)
> +#define FS1603_STATUS_OVER_CURRENT	BIT(5)
> +#define FS1603_STATUS_OVER_TEMP		BIT(4)
> +
> +/* OV_Threshold[1:0] in percent of programmed VOUT; OT_Threshold[1:0] in degC. */
> +static const unsigned int fs1603_ov_threshold_pct[] = { 105, 110, 115, 120 };
> +static const unsigned int fs1603_ot_threshold_c[] = { 75, 85, 125, 145 };
> +
> +/*
> + * Voltage telemetry is a linear step and base, both fixed per variant.
> + * Current is raw/32 A except on the FS1606-0600, which applies a calibration
> + * correction derived from FS1603_REG_IOUT_GAIN and the output voltage.
> + */
> +struct fs1603_info {
> +	unsigned int vout_step_mv;
> +	unsigned int vout_base_mv;
> +	u8 ocset_default;
> +	bool iout_gain_corrected;
> +};
> +
> +enum fs1603_model {
> +	fs1603,
> +	fs1604,
> +	fs1606,
> +	fs1606_0600,
> +	fs1606_2500,
> +	fs1006,
> +};
> +
> +/*
> + * The FS1606 reports at 10mV/300mV except for the -2500 preset, which uses the
> + * same 20mV/600mV encoding as the higher-voltage family members.
> + */
> +static const struct fs1603_info fs1603_models[] = {
> +	[fs1603]      = { .vout_step_mv = 20, .vout_base_mv = 600,
> +			  .ocset_default = FS1603_OCSET_DEFAULT_FS1603 },
> +	[fs1604]      = { .vout_step_mv = 20, .vout_base_mv = 600,
> +			  .ocset_default = FS1603_OCSET_DEFAULT_FS1604 },
> +	[fs1606]      = { .vout_step_mv = 10, .vout_base_mv = 300,
> +			  .ocset_default = FS1603_OCSET_DEFAULT_FS1606 },
> +	[fs1606_0600] = { .vout_step_mv = 10, .vout_base_mv = 300,
> +			  .ocset_default = FS1603_OCSET_DEFAULT_FS1606,
> +			  .iout_gain_corrected = true },
> +	[fs1606_2500] = { .vout_step_mv = 20, .vout_base_mv = 600,
> +			  .ocset_default = FS1603_OCSET_DEFAULT_FS1606 },
> +	[fs1006]      = { .vout_step_mv = 20, .vout_base_mv = 600,
> +			  .ocset_default = FS1603_OCSET_DEFAULT_FS1006 },
> +};
> +
> +/*
> + * Every register is a byte, and every read is live telemetry, so nothing is
> + * cached. regmap is used for the uniform accessors and the debugfs dump.
> + */
> +static const struct regmap_config fs1603_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +	.max_register = FS1603_REG_FB,
> +	.cache_type = REGCACHE_NONE,
> +};
> +
> +struct fs1603_data {
> +	struct regmap *regmap;
> +	const struct fs1603_info *info;
> +	u32 fb_ratio_num;
> +	u32 fb_ratio_den;
> +};
> +
> +static int fs1603_read_vout_mv(struct fs1603_data *data, long *val)
> +{
> +	unsigned int raw;
> +	int err;
> +
> +	err = regmap_read(data->regmap, FS1603_REG_VOUT, &raw);
> +	if (err)
> +		return err;
> +
> +	*val = raw * data->info->vout_step_mv + data->info->vout_base_mv;
> +	return 0;
> +}
> +
> +/*
> + * Output current in mA.
> + *
> + * Every variant but the FS1606-0600 reports raw/32 A directly. The -0600
> + * additionally applies, with G taken from FS1603_REG_IOUT_GAIN bits [7:2]:
> + *
> + *   I = raw/32 - (9.05 - 0.24 * G) * Vout - 0.356 * G + 13.1
> + *
> + * Scaled to milliamps and millivolts so it stays in integer arithmetic:
> + *
> + *   I_mA = raw * 125 / 4
> + *          - ((9050 - 240 * G) * Vout_mV) / 1000
> + *          - 356 * G
> + *          + 13100
> + */
> +static int fs1603_read_iout_ma(struct fs1603_data *data, long *val)
> +{
> +	unsigned int raw, gain;
> +	long vout_mv;
> +	int err;
> +
> +	err = regmap_read(data->regmap, FS1603_REG_IOUT, &raw);
> +	if (err)
> +		return err;
> +
> +	*val = raw * 125 / 4;
> +
> +	if (!data->info->iout_gain_corrected)
> +		return 0;
> +
> +	err = regmap_read(data->regmap, FS1603_REG_IOUT_GAIN, &gain);
> +	if (err)
> +		return err;
> +	gain = FIELD_GET(FS1603_IOUT_GAIN_MASK, gain);
> +
> +	err = fs1603_read_vout_mv(data, &vout_mv);
> +	if (err)
> +		return err;
> +
> +	*val -= ((9050 - 240 * (long)gain) * vout_mv) / 1000;
> +	*val -= 356 * (long)gain;
> +	*val += 13100;
> +
> +	if (*val < 0)
> +		*val = 0;
> +
> +	return 0;
> +}
> +
> +/*
> + * The 9-bit VOUT_SET code steps at half the telemetry resolution from a base
> + * of 80 steps.
> + */
> +static int fs1603_read_vout_set_mv(struct fs1603_data *data, long *val)
> +{
> +	unsigned int hi, lo;
> +	int err;
> +
> +	err = regmap_read(data->regmap, FS1603_REG_VOUT_SET_HI, &hi);
> +	if (err)
> +		return err;
> +	err = regmap_read(data->regmap, FS1603_REG_VOUT_SET_LO, &lo);
> +	if (err)
> +		return err;
> +
> +	*val = ((FIELD_GET(FS1603_VOUT_SET_HI_MASK, hi) << 8 | lo) + 80) *
> +	       data->info->vout_step_mv / 2;
> +	return 0;
> +}
> +
> +/* Fb has no documented encoding; it decodes with the VOUT step and base. */
> +static int fs1603_read_fb_mv(struct fs1603_data *data, long *val)
> +{
> +	unsigned int raw;
> +	int err;
> +
> +	err = regmap_read(data->regmap, FS1603_REG_FB, &raw);
> +	if (err)
> +		return err;
> +
> +	*val = raw * data->info->vout_step_mv + data->info->vout_base_mv;
> +	return 0;
> +}
> +
> +/*
> + * A board that raises the rail with a feedback divider leaves VOUT_SET at the
> + * feedback target, and Fb then reads well below VOUT. The divider is fixed in
> + * hardware, so measure its ratio once. Without a divider Fb reads the output
> + * itself, and the ratio stays one so the limit does not follow ADC noise.
> + */
> +static int fs1603_measure_fb_ratio(struct fs1603_data *data)
> +{
> +	long vout_mv, fb_mv;
> +	int err;
> +
> +	data->fb_ratio_num = 1;
> +	data->fb_ratio_den = 1;
> +
> +	err = fs1603_read_vout_mv(data, &vout_mv);
> +	if (err)
> +		return err;
> +	err = fs1603_read_fb_mv(data, &fb_mv);
> +	if (err)
> +		return err;
> +
> +	if (fb_mv > 0 && vout_mv > fb_mv + 4 * data->info->vout_step_mv) {
> +		data->fb_ratio_num = vout_mv;
> +		data->fb_ratio_den = fb_mv;
> +	}
> +	return 0;
> +}
> +
> +/*
> + * OVP trips at OV_Threshold percent of the VOUT_SET target, measured at the
> + * feedback pin. Scale it by the feedback divider ratio to report it in the
> + * same rail domain as in1_input.
> + */
> +static int fs1603_read_vout_crit_mv(struct fs1603_data *data, long *val)
> +{
> +	unsigned int raw;
> +	long vout_set_mv;
> +	int err;
> +
> +	err = regmap_read(data->regmap, FS1603_REG_OV_THRESHOLD, &raw);
> +	if (err)
> +		return err;
> +	err = fs1603_read_vout_set_mv(data, &vout_set_mv);
> +	if (err)
> +		return err;
> +
> +	raw = FIELD_GET(FS1603_OV_THRESHOLD_MASK, raw);
> +	*val = DIV_ROUND_CLOSEST_ULL((u64)fs1603_ov_threshold_pct[raw] *
> +				     vout_set_mv * data->fb_ratio_num,
> +				     100 * data->fb_ratio_den);
> +	return 0;
> +}
> +
> +static int fs1603_read_status_bit(struct fs1603_data *data, u8 mask,
> +				  long *val)
> +{
> +	unsigned int status;
> +	int err;
> +
> +	err = regmap_read(data->regmap, FS1603_REG_STATUS, &status);
> +	if (err)
> +		return err;
> +
> +	*val = !!(status & mask);
> +	return 0;
> +}
> +
> +static int fs1603_read_in(struct fs1603_data *data, u32 attr, int channel,
> +			  long *val)
> +{
> +	unsigned int raw;
> +	int err;
> +
> +	switch (attr) {
> +	case hwmon_in_input:
> +		if (channel == 0) {
> +			err = regmap_read(data->regmap, FS1603_REG_PVIN, &raw);
> +			if (err)
> +				return err;
> +			/* PVIN reports in 1/16 V steps. */
> +			*val = raw * 1000 / 16;
> +			return 0;
> +		}
> +		return fs1603_read_vout_mv(data, val);
> +	case hwmon_in_crit:
> +		return fs1603_read_vout_crit_mv(data, val);
> +	case hwmon_in_alarm:
> +		return fs1603_read_status_bit(data, FS1603_STATUS_OVER_VOLTAGE,
> +					      val);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static int fs1603_read_curr(struct fs1603_data *data, u32 attr, long *val)
> +{
> +	switch (attr) {
> +	case hwmon_curr_input:
> +		return fs1603_read_iout_ma(data, val);
> +	case hwmon_curr_alarm:
> +		return fs1603_read_status_bit(data, FS1603_STATUS_OVER_CURRENT,
> +					      val);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static int fs1603_read_temp_crit_mc(struct fs1603_data *data, long *val)
> +{
> +	unsigned int raw;
> +	int err;
> +
> +	err = regmap_read(data->regmap, FS1603_REG_OT_THRESHOLD, &raw);
> +	if (err)
> +		return err;
> +
> +	*val = fs1603_ot_threshold_c[FIELD_GET(FS1603_OT_THRESHOLD_MASK, raw)] * 1000;
> +	return 0;
> +}
> +
> +static int fs1603_read_temp(struct fs1603_data *data, u32 attr, long *val)
> +{
> +	unsigned int raw;
> +	int err;
> +
> +	switch (attr) {
> +	case hwmon_temp_input:
> +		err = regmap_read(data->regmap, FS1603_REG_TEMP, &raw);
> +		if (err)
> +			return err;
> +		/* TEMP_REPORT is degC directly: 1 degC per LSB, no offset. */
> +		*val = raw * 1000;
> +		return 0;
> +	case hwmon_temp_crit:
> +		return fs1603_read_temp_crit_mc(data, val);
> +	case hwmon_temp_alarm:
> +		return fs1603_read_status_bit(data, FS1603_STATUS_OVER_TEMP,
> +					      val);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static int fs1603_read(struct device *dev, enum hwmon_sensor_types type,
> +		       u32 attr, int channel, long *val)
> +{
> +	struct fs1603_data *data = dev_get_drvdata(dev);
> +
> +	switch (type) {
> +	case hwmon_in:
> +		return fs1603_read_in(data, attr, channel, val);
> +	case hwmon_curr:
> +		return fs1603_read_curr(data, attr, val);
> +	case hwmon_temp:
> +		return fs1603_read_temp(data, attr, val);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static int fs1603_read_string(struct device *dev, enum hwmon_sensor_types type,
> +			      u32 attr, int channel, const char **str)
> +{
> +	if (type != hwmon_in || attr != hwmon_in_label)
> +		return -EOPNOTSUPP;
> +
> +	*str = channel == 0 ? "vin" : "vout";
> +	return 0;
> +}
> +
> +static umode_t fs1603_is_visible(const void *data, enum hwmon_sensor_types type,
> +				 u32 attr, int channel)
> +{
> +	switch (type) {
> +	case hwmon_in:
> +		switch (attr) {
> +		case hwmon_in_input:
> +		case hwmon_in_label:
> +			return 0444;
> +		case hwmon_in_crit:
> +		case hwmon_in_alarm:
> +			/* OVP and its alarm describe the regulated output only. */
> +			return channel == 1 ? 0444 : 0;
> +		default:
> +			return 0;
> +		}
> +	case hwmon_curr:
> +	case hwmon_temp:
> +		return 0444;
> +	default:
> +		return 0;
> +	}
> +}
> +
> +static const struct hwmon_ops fs1603_ops = {
> +	.is_visible = fs1603_is_visible,
> +	.read = fs1603_read,
> +	.read_string = fs1603_read_string,
> +};
> +
> +static const struct hwmon_channel_info *fs1603_channel_info[] = {
> +	HWMON_CHANNEL_INFO(in, HWMON_I_INPUT | HWMON_I_LABEL,
> +			   HWMON_I_INPUT | HWMON_I_LABEL | HWMON_I_CRIT |
> +			   HWMON_I_ALARM),
> +	HWMON_CHANNEL_INFO(curr, HWMON_C_INPUT | HWMON_C_ALARM),
> +	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_CRIT | HWMON_T_ALARM),
> +	NULL
> +};
> +
> +static const struct hwmon_chip_info fs1603_chip_info = {
> +	.ops = &fs1603_ops,
> +	.info = fs1603_channel_info,
> +};
> +
> +static int fs1603_probe(struct i2c_client *client)
> +{
> +	struct device *dev = &client->dev;
> +	char *name;
> +	struct fs1603_data *data;
> +	struct device *hwmon;
> +	unsigned int ocset;
> +	int err;
> +
> +	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
> +		return dev_err_probe(dev, -ENODEV,
> +				     "SMBus byte data not supported\n");
> +
> +	name = devm_hwmon_sanitize_name(dev, client->name);
> +	if (IS_ERR(name))
> +		return PTR_ERR(name);
> +
> +	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	data->regmap = devm_regmap_init_i2c(client, &fs1603_regmap_config);
> +	if (IS_ERR(data->regmap))
> +		return dev_err_probe(dev, PTR_ERR(data->regmap),
> +				     "failed to allocate regmap\n");
> +
> +	data->info = i2c_get_match_data(client);
> +	if (!data->info)
> +		return dev_err_probe(dev, -ENODEV, "no match data for %s\n",
> +				     client->name);
> +
> +	err = regmap_read(data->regmap, FS1603_REG_OCSET, &ocset);
> +	if (err)
> +		return dev_err_probe(dev, err, "failed to read OCSet\n");
> +
> +	ocset = FIELD_GET(FS1603_OCSET_LEVEL, ocset);
> +	if (ocset != data->info->ocset_default)
> +		dev_warn(dev, "OCSet %u differs from the %s default %u\n",
> +			 ocset, client->name, data->info->ocset_default);
> +
> +	err = fs1603_measure_fb_ratio(data);
> +	if (err)
> +		return dev_err_probe(dev, err,
> +				     "failed to read the feedback ratio\n");
> +
> +	hwmon = devm_hwmon_device_register_with_info(dev, name, data,
> +						     &fs1603_chip_info, NULL);
> +	return PTR_ERR_OR_ZERO(hwmon);
> +}
> +
> +static const struct i2c_device_id fs1603_id[] = {
> +	{ .name = "fs1603",
> +	  .driver_data = (kernel_ulong_t)&fs1603_models[fs1603] },
> +	{ .name = "fs1604",
> +	  .driver_data = (kernel_ulong_t)&fs1603_models[fs1604] },
> +	{ .name = "fs1606",
> +	  .driver_data = (kernel_ulong_t)&fs1603_models[fs1606] },
> +	{ .name = "fs1606_0600",
> +	  .driver_data = (kernel_ulong_t)&fs1603_models[fs1606_0600] },
> +	{ .name = "fs1606_2500",
> +	  .driver_data = (kernel_ulong_t)&fs1603_models[fs1606_2500] },
> +	{ .name = "fs1006_5000",
> +	  .driver_data = (kernel_ulong_t)&fs1603_models[fs1006] },
> +	{ .name = "fs1006_3300",
> +	  .driver_data = (kernel_ulong_t)&fs1603_models[fs1006] },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(i2c, fs1603_id);
> +
> +static const struct of_device_id fs1603_of_match[] = {
> +	{ .compatible = "tdk,fs1603", .data = &fs1603_models[fs1603] },
> +	{ .compatible = "tdk,fs1604", .data = &fs1603_models[fs1604] },
> +	{ .compatible = "tdk,fs1606", .data = &fs1603_models[fs1606] },
> +	{ .compatible = "tdk,fs1606-0600",
> +	  .data = &fs1603_models[fs1606_0600] },
> +	{ .compatible = "tdk,fs1606-2500",
> +	  .data = &fs1603_models[fs1606_2500] },
> +	{ .compatible = "tdk,fs1006-5000",
> +	  .data = &fs1603_models[fs1006] },
> +	{ .compatible = "tdk,fs1006-3300",
> +	  .data = &fs1603_models[fs1006] },

Why those extra compatibles ? I can see that -0600 and -2500 are
needed, but the others could just use tdk,fs1606.

Thanks,
Guenter

> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, fs1603_of_match);
> +
> +static struct i2c_driver fs1603_driver = {
> +	.driver = {
> +		.name	= "fs1603",
> +		.of_match_table = fs1603_of_match,
> +	},
> +	.probe = fs1603_probe,
> +	.id_table = fs1603_id,
> +};
> +module_i2c_driver(fs1603_driver);
> +
> +MODULE_AUTHOR("Kevin Jia <kjia@xxxxxxxxxx>");
> +MODULE_DESCRIPTION("TDK FS160x uPOL DC-DC converter telemetry driver");
> +MODULE_LICENSE("GPL");