Date: Mon, 10 Jun 2024 09:21:06 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Noah Wang <noahwang.wang@...look.com>, robh@...nel.org,
 krzk+dt@...nel.org, conor+dt@...nel.org, jdelvare@...e.com
Cc: corbet@....net, Delphine_CC_Chiu@...ynn.com, peteryin.openbmc@...il.com,
 javier.carrasco.cruz@...il.com, patrick.rudolph@...ements.com,
 bhelgaas@...gle.com, lukas@...ner.de, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org,
 linux-doc@...r.kernel.org, linux-i2c@...r.kernel.org
Subject: Re: [PATCH 2/4] hwmon: add MP2993 driver

On 6/7/24 02:05, Noah Wang wrote:
> Add support for MPS VR controller mp2993. This driver exposes
> telemetry and limit value readings and writtings.
> 
> Signed-off-by: Noah Wang <noahwang.wang@...look.com>
> ---
>   Documentation/hwmon/index.rst  |   1 +
>   Documentation/hwmon/mp2993.rst | 150 ++++++++++++++++++
>   MAINTAINERS                    |   7 +
>   drivers/hwmon/pmbus/Kconfig    |   9 ++
>   drivers/hwmon/pmbus/Makefile   |   1 +
>   drivers/hwmon/pmbus/mp2993.c   | 269 +++++++++++++++++++++++++++++++++
>   6 files changed, 437 insertions(+)
>   create mode 100644 Documentation/hwmon/mp2993.rst
>   create mode 100644 drivers/hwmon/pmbus/mp2993.c
> 
> diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
> index 03d313af469a..9d9d55b889f2 100644
> --- a/Documentation/hwmon/index.rst
> +++ b/Documentation/hwmon/index.rst
> @@ -166,6 +166,7 @@ Hardware Monitoring Kernel Drivers
>      mp2856
>      mp2888
>      mp2975
> +   mp2993
>      mp5023
>      mp5990
>      mpq8785
> diff --git a/Documentation/hwmon/mp2993.rst b/Documentation/hwmon/mp2993.rst
> new file mode 100644
> index 000000000000..a14bb30969f9
> --- /dev/null
> +++ b/Documentation/hwmon/mp2993.rst
> @@ -0,0 +1,150 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +Kernel driver mp2993
> +====================
> +
> +Supported chips:
> +
> +  * MPS mp2993
> +
> +    Prefix: 'mp2993'
> +
> +  * Datasheet
> +    https://scnbwymvp-my.sharepoint.com/:f:/g/personal/admin_scnbwy_com/Eth4kX1_J1hMsaASHiOYL4QBHU5a75r-tRfLKbHnJFdKLQ?e=vxj3DF
> +
> +Author:
> +
> +	Noah Wang <noahwang.wang@...look.com>
> +
> +Description
> +-----------
> +
> +This driver implements support for Monolithic Power Systems, Inc. (MPS)
> +MP2993 Dual Loop Digital Multi-phase Controller.
> +
> +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**
> +
> +**in1_lcrit**
> +
> +**in1_lcrit_alarm**
> +
> +**in1_max**
> +
> +**in1_max_alarm**
> +
> +**in1_min**
> +
> +**in1_min_alarm**
> +
> +The driver provides the following attributes for output voltage:
> +
> +**in2_input**
> +
> +**in2_label**
> +
> +**in2_crit**
> +
> +**in2_crit_alarm**
> +
> +**in2_lcrit**
> +
> +**in2_lcrit_alarm**
> +
> +**in3_input**
> +
> +**in3_label**
> +
> +**in3_crit**
> +
> +**in3_crit_alarm**
> +
> +**in3_lcrit**
> +
> +**in3_lcrit_alarm**
> +
> +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**
> +
> +**curr2_crit**
> +
> +**curr2_crit_alarm**
> +
> +**curr2_max**
> +
> +**curr2_max_alarm**
> +
> +**curr3_input**
> +
> +**curr3_label**
> +
> +**curr3_crit**
> +
> +**curr3_crit_alarm**
> +
> +**curr3_max**
> +
> +**curr3_max_alarm**
> +
> +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**
> +
> +**power3_input**
> +
> +**power3_label**
> +
> +The driver provides the following attributes for temperature:
> +
> +**temp1_input**
> +
> +**temp1_crit**
> +
> +**temp1_crit_alarm**
> +
> +**temp1_max**
> +
> +**temp1_max_alarm**
> +
> +**temp2_input**
> +
> +**temp2_crit**
> +
> +**temp2_crit_alarm**
> +
> +**temp2_max**
> +
> +**temp2_max_alarm**
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 8754ac2c259d..f47f3e13b004 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -15258,6 +15258,13 @@ S:	Maintained
>   F:	Documentation/devicetree/bindings/leds/backlight/mps,mp3309c.yaml
>   F:	drivers/video/backlight/mp3309c.c
>   
> ++MPS MP2993 DRIVER
> ++M:	Noah Wang <noahwang.wang@...look.com>
> ++L:	linux-hwmon@...r.kernel.org
> ++S:	Maintained
> ++F:	Documentation/hwmon/mp2993.rst
> ++F:	drivers/hwmon/pmbus/mp2993.c
> +
>   MR800 AVERMEDIA USB FM RADIO DRIVER
>   M:	Alexey Klimov <klimov.linux@...il.com>
>   L:	linux-media@...r.kernel.org
> diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
> index 08e82c457356..d875d31ce84c 100644
> --- a/drivers/hwmon/pmbus/Kconfig
> +++ b/drivers/hwmon/pmbus/Kconfig
> @@ -346,6 +346,15 @@ config SENSORS_MP2975
>   	  This driver can also be built as a module. If so, the module will
>   	  be called mp2975.
>   
> +config SENSORS_MP2993
> +	tristate "MPS MP2993"
> +	help
> +	  If you say yes here you get hardware monitoring support for MPS
> +	  MP2993 Dual Loop Digital Multi-Phase Controller.
> +
> +	  This driver can also be built as a module. If so, the module will
> +	  be called mp2993.
> +
>   config SENSORS_MP2975_REGULATOR
>   	depends on SENSORS_MP2975 && REGULATOR
>   	bool "Regulator support for MPS MP2975"
> diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
> index 2279b3327bbf..312d3f0c0540 100644
> --- a/drivers/hwmon/pmbus/Makefile
> +++ b/drivers/hwmon/pmbus/Makefile
> @@ -37,6 +37,7 @@ obj-$(CONFIG_SENSORS_MAX8688)	+= max8688.o
>   obj-$(CONFIG_SENSORS_MP2856)	+= mp2856.o
>   obj-$(CONFIG_SENSORS_MP2888)	+= mp2888.o
>   obj-$(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_MPQ7932)	+= mpq7932.o
> diff --git a/drivers/hwmon/pmbus/mp2993.c b/drivers/hwmon/pmbus/mp2993.c
> new file mode 100644
> index 000000000000..43432b8d4faf
> --- /dev/null
> +++ b/drivers/hwmon/pmbus/mp2993.c
> @@ -0,0 +1,269 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Hardware monitoring driver for MPS Multi-phase Digital VR Controllers(MP2993)
> + */
> +
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include "pmbus.h"
> +
> +#define MP2993_VOUT_OVUV_UINT	125
> +#define MP2993_VOUT_OVUV_DIV	64
> +#define MP2993_VIN_LIMIT_UINT	1
> +#define MP2993_VIN_LIMIT_DIV	8
> +#define MP2993_READ_VIN_UINT	1
> +#define MP2993_READ_VIN_DIV	32
> +
> +#define MP2993_PAGE_NUM	2
> +
> +#define MP2993_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)
> +
> +#define MP2993_RAIL2_FUNC	(PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT | \
> +							 PMBUS_HAVE_POUT | PMBUS_HAVE_TEMP | \
> +							 PMBUS_HAVE_STATUS_VOUT | \
> +							 PMBUS_HAVE_STATUS_IOUT | \
> +							 PMBUS_HAVE_STATUS_TEMP | \
> +							 PMBUS_HAVE_STATUS_INPUT)
> +
> +/* Converts a linear11 data exponent to a specified value */
> +static u16 mp2993_linear11_exponent_transfer(u16 word, u16 expect_exponent)
> +{
> +	s16 exponent, mantissa, target_exponent;
> +
> +	exponent = ((s16)word) >> 11;
> +	mantissa = ((s16)((word & 0x7ff) << 5)) >> 5;
> +	target_exponent = (s16)((expect_exponent & 0x1f) << 11) >> 11;
> +
> +	if (exponent > target_exponent)
> +		mantissa = mantissa << (exponent - target_exponent);
> +	else
> +		mantissa = mantissa >> (target_exponent - exponent);
> +
> +	return (mantissa & 0x7ff) | ((expect_exponent << 11) & 0xf800);
> +}
> +
> +static int
> +mp2993_set_vout_format(struct i2c_client *client, int page, int format)
> +{
> +	int ret;
> +
> +	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, page);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = i2c_smbus_write_byte_data(client, PMBUS_VOUT_MODE, format);
> +	if (ret < 0)
> +		return ret;

	return i2c_smbus_write_byte_data(...);

> +
> +	return 0;
> +}
> +
> +static int mp2993_identify(struct i2c_client *client, struct pmbus_driver_info *info)
> +{
> +	int ret;
> +
> +	/* Set vout to direct format for rail1. */
> +	ret = mp2993_set_vout_format(client, 0, PB_VOUT_MODE_DIRECT);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Set vout to direct format for rail2. */
> +	ret = mp2993_set_vout_format(client, 1, PB_VOUT_MODE_DIRECT);
> +	if (ret < 0)
> +		return ret;
> +
> +	return ret;


In other words,
	if (ret < 0)
		return ret;
	else
		return ret;

Please, don't do that.

	return mp2993_set_vout_format(...);

> +}
> +
> +static int mp2993_read_word_data(struct i2c_client *client, int page, int phase,
> +				 int reg)
> +{
> +	int ret;
> +
> +	switch (reg) {
> +	case PMBUS_VOUT_OV_FAULT_LIMIT:
> +	case PMBUS_VOUT_UV_FAULT_LIMIT:
> +		ret = pmbus_read_word_data(client, page, phase, reg);
> +		if (ret < 0)
> +			return ret;
> +
> +		ret = DIV_ROUND_CLOSEST(ret * MP2993_VOUT_OVUV_UINT, MP2993_VOUT_OVUV_DIV);
> +		break;
> +	case PMBUS_OT_FAULT_LIMIT:
> +	case PMBUS_OT_WARN_LIMIT:
> +		/*
> +		 * The MP2993 ot fault limit value and ot warn limit value
> +		 * per rail are always the same, so only PMBUS_OT_FAULT_LIMIT
> +		 * and PMBUS_OT_WARN_LIMIT register in page 0 are defined to
> +		 * indicates the limit value.
> +		 */
> +		ret = pmbus_read_word_data(client, 0, phase, reg);
> +		break;
> +	case PMBUS_READ_VIN:
> +		/* The MP2993 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)) * MP2993_READ_VIN_UINT,
> +					MP2993_READ_VIN_DIV);
> +		break;
> +	case PMBUS_VIN_OV_FAULT_LIMIT:
> +	case PMBUS_VIN_OV_WARN_LIMIT:
> +	case PMBUS_VIN_UV_WARN_LIMIT:
> +	case PMBUS_VIN_UV_FAULT_LIMIT:
> +		/* The MP2993 vin 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)) * MP2993_VIN_LIMIT_UINT,
> +					MP2993_VIN_LIMIT_DIV);
> +		break;
> +	case PMBUS_READ_IOUT:
> +	case PMBUS_READ_IIN:
> +	case PMBUS_IIN_OC_WARN_LIMIT:
> +	case PMBUS_IOUT_OC_FAULT_LIMIT:
> +	case PMBUS_IOUT_OC_WARN_LIMIT:
> +	case PMBUS_READ_VOUT:
> +	case PMBUS_READ_PIN:
> +	case PMBUS_READ_POUT:
> +	case PMBUS_READ_TEMPERATURE_1:
> +		ret = -ENODATA;
> +		break;
> +	default:
> +		ret = -EINVAL;
> +		break;
> +	}
> +
> +	return ret;
> +}
> +
> +static int mp2993_write_word_data(struct i2c_client *client, int page, int reg,
> +				  u16 word)
> +{
> +	int ret;
> +
> +	switch (reg) {
> +	case PMBUS_VOUT_OV_FAULT_LIMIT:
> +	case PMBUS_VOUT_UV_FAULT_LIMIT:
> +		ret = DIV_ROUND_CLOSEST(word * MP2993_VOUT_OVUV_DIV, MP2993_VOUT_OVUV_UINT);
> +		ret = pmbus_write_word_data(client, 0, reg, ret);
> +		break;
> +	case PMBUS_OT_FAULT_LIMIT:
> +	case PMBUS_OT_WARN_LIMIT:
> +		/*
> +		 * The MP2993 ot fault limit value and ot warn limit value
> +		 * per rail are always the same, so only PMBUS_OT_FAULT_LIMIT
> +		 * and PMBUS_OT_WARN_LIMIT register in page 0 are defined to
> +		 * config the ot limit value.
> +		 */
> +		ret = pmbus_write_word_data(client, 0, reg, word);
> +		break;
> +	case PMBUS_VIN_OV_FAULT_LIMIT:
> +	case PMBUS_VIN_OV_WARN_LIMIT:
> +	case PMBUS_VIN_UV_WARN_LIMIT:
> +	case PMBUS_VIN_UV_FAULT_LIMIT:
> +		/* The MP2993 vin limit scale is (1/8V)/Lsb */
> +		ret = pmbus_write_word_data(client, 0, reg,
> +					    DIV_ROUND_CLOSEST(word * MP2993_VIN_LIMIT_DIV,
> +							      MP2993_VIN_LIMIT_UINT));
> +		break;
> +	case PMBUS_IIN_OC_WARN_LIMIT:
> +		/*
> +		 * The PMBUS_IIN_OC_WARN_LIMIT of MP2993 is linear11 format,
> +		 * and the exponent is a constant value(5'b00000)， so the
> +		 * exponent of word parameter should be converted to 5'b00000.
> +		 */
> +		ret = pmbus_write_word_data(client, page, reg,
> +					    mp2993_linear11_exponent_transfer(word, 0x00));
> +		break;
> +		//
> +	case PMBUS_IOUT_OC_FAULT_LIMIT:
> +	case PMBUS_IOUT_OC_WARN_LIMIT:
> +		/*
> +		 * The PMBUS_IOUT_OC_FAULT_LIMIT and PMBUS_IOUT_OC_WARN_LIMIT
> +		 * of MP2993 can be regarded as linear11 format, and the
> +		 * exponent is a 5'b00001 or 5'b00000. To ensure a larger
> +		 * range of limit value, so the exponent of word parameter
> +		 * should be converted to 5'b00001.
> +		 */
> +		ret = pmbus_write_word_data(client, page, reg,
> +					    mp2993_linear11_exponent_transfer(word, 0x01));
> +		break;
> +	default:
> +		ret = -EINVAL;
> +		break;
> +	}
> +
> +	return ret;
> +}
> +
> +static struct pmbus_driver_info mp2993_info = {
> +	.pages = MP2993_PAGE_NUM,
> +	.format[PSC_VOLTAGE_IN] = direct,
> +	.format[PSC_CURRENT_IN] = linear,
> +	.format[PSC_CURRENT_OUT] = linear,
> +	.format[PSC_TEMPERATURE] = direct,
> +	.format[PSC_POWER] = linear,
> +	.format[PSC_VOLTAGE_OUT] = direct,
> +
> +	.m[PSC_VOLTAGE_OUT] = 1,
> +	.R[PSC_VOLTAGE_OUT] = 3,
> +	.b[PSC_VOLTAGE_OUT] = 0,
> +
> +	.m[PSC_VOLTAGE_IN] = 1,
> +	.R[PSC_VOLTAGE_IN] = 0,
> +	.b[PSC_VOLTAGE_IN] = 0,
> +
> +	.m[PSC_TEMPERATURE] = 1,
> +	.R[PSC_TEMPERATURE] = 0,
> +	.b[PSC_TEMPERATURE] = 0,
> +
> +	.func[0] = MP2993_RAIL1_FUNC,
> +	.func[1] = MP2993_RAIL2_FUNC,
> +	.read_word_data = mp2993_read_word_data,
> +	.write_word_data = mp2993_write_word_data,
> +	.identify = mp2993_identify,
> +};
> +
> +static int mp2993_probe(struct i2c_client *client)
> +{
> +	return pmbus_do_probe(client, &mp2993_info);
> +}
> +
> +static const struct i2c_device_id mp2993_id[] = {
> +	{"mp2993", 0},
> +	{}
> +};
> +MODULE_DEVICE_TABLE(i2c, mp2993_id);
> +
> +static const struct of_device_id __maybe_unused mp2993_of_match[] = {
> +	{.compatible = "mps,mp2993"},
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, mp2993_of_match);
> +
> +static struct i2c_driver mp2993_driver = {
> +	.driver = {
> +		.name = "mp2993",
> +		.of_match_table = mp2993_of_match,
> +	},
> +	.probe = mp2993_probe,
> +	.id_table = mp2993_id,
> +};
> +
> +module_i2c_driver(mp2993_driver);
> +
> +MODULE_AUTHOR("Noah Wang <noahwang.wang@...look.com>");
> +MODULE_DESCRIPTION("PMBus driver for MPS MP2993");
> +MODULE_LICENSE("GPL");
> +MODULE_IMPORT_NS(PMBUS);

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