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Date: Mon, 13 May 2024 07:20:22 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Noah Wang <noahwang.wang@...look.com>, jdelvare@...e.com
Cc: linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hwmon: add MP2891 driver
On 5/12/24 22:52, Noah Wang wrote:
> This driver is designed for MPS VR controller mp2891. The input
> voltage, output voltage, input current, output current, input
> power, output power and temperature of per rail can be obtained
> from hwmon sysfs that the driver provided.
>
> Signed-off-by: Noah Wang <noahwang.wang@...look.com>
> ---
> Documentation/hwmon/mp2891.rst | 95 +++++++++++++++
Needs to be added to index.rst.
> drivers/hwmon/pmbus/Kconfig | 9 ++
> drivers/hwmon/pmbus/Makefile | 1 +
> drivers/hwmon/pmbus/mp2891.c | 210 +++++++++++++++++++++++++++++++++
> 4 files changed, 315 insertions(+)
> create mode 100644 Documentation/hwmon/mp2891.rst
> create mode 100644 drivers/hwmon/pmbus/mp2891.c
>
> diff --git a/Documentation/hwmon/mp2891.rst b/Documentation/hwmon/mp2891.rst
> new file mode 100644
> index 000000000..eaf73fe60
> --- /dev/null
> +++ b/Documentation/hwmon/mp2891.rst
> @@ -0,0 +1,95 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +Kernel driver mp2891
> +====================
> +
> +Supported chips:
> +
> + * MPS mp2891
> +
> + Prefix: 'mp2891'
> +
> + * Datasheet
> +
> + Publicly available at the MPS website : https://www.monolithicpower.com/en/mp2891.html
No, it isn't. It is not even accessible with an account (the provided "datasheet"
is a useless one-pager).
> +
> +Author:
> +
> + Noah Wang <noahwang.wang@...look.com>
> +
> +Description
> +-----------
> +
> +This driver implements support for Monolithic Power Systems, Inc. (MPS)
> +MP2891 Multi-phase Digital VR Controller.
> +
> +Device compliant with:
> +
> +- PMBus rev 1.3 interface.
> +
> +Device supports direct and linear format for reading input voltage,
> +output voltage, input currect, output current, input power, output
> +power, and temperature.
> +
> +The driver exports the following attributes via the 'sysfs' files
> +for input voltage:
> +
> +**in1_input**
> +
> +**in1_label**
> +
> +The driver provides the following attributes for output voltage:
> +
> +**in2_input**
> +
> +**in2_label**
> +
> +**in3_input**
> +
> +**in3_label**
> +
> +The driver provides the following attributes for input current:
> +
> +**curr1_input**
> +
> +**curr1_label**
> +
> +**curr2_input**
> +
> +**curr2_label**
> +
> +The driver provides the following attributes for output current:
> +
> +**curr3_input**
> +
> +**curr3_label**
> +
> +**curr4_input**
> +
> +**curr4_label**
> +
> +The driver provides the following attributes for input power:
> +
> +**power1_input**
> +
> +**power1_label**
> +
> +**power2_input**
> +
> +**power2_label**
> +
> +The driver provides the following attributes for output power:
> +
> +**power3_input**
> +
> +**power3_label**
> +
> +**power4_input**
> +
> +**power4_label**
> +
> +The driver provides the following attributes for temperature:
> +
> +**temp1_input**
> +
> +**temp2_input**
> diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
> index 557ae0c41..b8b6c7724 100644
> --- a/drivers/hwmon/pmbus/Kconfig
> +++ b/drivers/hwmon/pmbus/Kconfig
> @@ -361,6 +361,15 @@ config SENSORS_MP5990
> This driver can also be built as a module. If so, the module will
> be called mp5990.
>
> +config SENSORS_MP2891
> + tristate "MPS MP2891"
> + help
> + If you say yes here you get hardware monitoring support for MPS
> + MP2891 Dual Loop Digital Multi-Phase Controller.
> +
> + This driver can also be built as a module. If so, the module will
> + be called mp2891.
> +
> 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 f14ecf03a..57b91c20e 100644
> --- a/drivers/hwmon/pmbus/Makefile
> +++ b/drivers/hwmon/pmbus/Makefile
> @@ -38,6 +38,7 @@ obj-$(CONFIG_SENSORS_MP2888) += mp2888.o
> obj-$(CONFIG_SENSORS_MP2975) += mp2975.o
> obj-$(CONFIG_SENSORS_MP5023) += mp5023.o
> obj-$(CONFIG_SENSORS_MP5990) += mp5990.o
> +obj-$(CONFIG_SENSORS_MP2891) += mp2891.o
> obj-$(CONFIG_SENSORS_MPQ7932) += mpq7932.o
> obj-$(CONFIG_SENSORS_MPQ8785) += mpq8785.o
> obj-$(CONFIG_SENSORS_PLI1209BC) += pli1209bc.o
> diff --git a/drivers/hwmon/pmbus/mp2891.c b/drivers/hwmon/pmbus/mp2891.c
> new file mode 100644
> index 000000000..c98d9ec6b
> --- /dev/null
> +++ b/drivers/hwmon/pmbus/mp2891.c
> @@ -0,0 +1,210 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Hardware monitoring driver for MPS Multi-phase Digital VR Controllers(MP2891)
> + */
> +
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include "pmbus.h"
> +
> +/* Vendor specific registers, the register READ_PIN_EST(0x94),
Please use standard multi-line comments.
> + * MFR_VOUT_LOOP_CTRL(0xBD) and READ_IIN_EST(0x95) redefine
> + * the standard PMBUS register.
That doesn't explain the reason for using the _EST registers
instead of the standard registers.
> + */
> +#define MFR_VOUT_LOOP_CTRL 0xBD
> +#define READ_PIN_EST 0x94
> +#define READ_IIN_EST 0x95
> +
> +#define MP2891_PAGE_NUM 2
> +
> +#define MP2891_RAIL1_FUNC (PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | \
> + PMBUS_HAVE_IOUT | PMBUS_HAVE_TEMP | \
> + PMBUS_HAVE_POUT | PMBUS_HAVE_PIN | \
> + PMBUS_HAVE_IIN | PMBUS_PHASE_VIRTUAL)
> +
> +#define MP2891_RAIL2_FUNC (PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT | \
> + PMBUS_HAVE_TEMP | PMBUS_HAVE_POUT | \
> + PMBUS_HAVE_IIN | PMBUS_PHASE_VIRTUAL)
What is the point of PMBUS_PHASE_VIRTUAL ?
> +
> +struct mp2891_data {
> + struct pmbus_driver_info info;
> +};
> +
> +#define to_mp2891_data(x) container_of(x, struct mp2891_data, info)
> +
Unused.
> +static int mp2891_read_byte_data(struct i2c_client *client, int page, int reg)
> +{
> + int ret;
> +
> + switch (reg) {
> + case PMBUS_VOUT_MODE:
> + ret = PB_VOUT_MODE_DIRECT;
Needs explanation.
> + break;
> + default:
> + ret = -EINVAL;
No status registers ? I do not believe this is correct.
> + break;
> + }
> +
> + return ret;
> +}
> +
> +static int mp2891_read_word_data(struct i2c_client *client, int page, int phase,
> + int reg)
> +{
> + int ret;
> +
> + switch (reg) {
> + case PMBUS_READ_VIN:
> + case PMBUS_READ_IOUT:
> + case PMBUS_READ_POUT:
> + case PMBUS_READ_VOUT:
> + case PMBUS_READ_TEMPERATURE_1:
> + ret = pmbus_read_word_data(client, page, phase, reg);
Use
return -ENODATA;
instead.
> + break;
> + case PMBUS_READ_IIN:
> + ret = pmbus_read_word_data(client, page, phase, READ_IIN_EST);
> + break;
> + case PMBUS_READ_PIN:
> + ret = pmbus_read_word_data(client, page, phase, READ_PIN_EST);
This needs an explanation. Why not use standard READ_IIN and READ_PIN ?
> + break;
> + default:
> + ret = -EINVAL;
No limit registers ? That seems extremely unlikely.
Given that you are essentially claiming that the chip would support
almost no standard registers, I'll need to see the datasheet to confirm.
> + break;
> + }
> +
> + return ret;
> +}
> +
> +static int
> +mp2891_identify_vout_scale(struct i2c_client *client, struct mp2891_data *data,
> + u32 reg, int page)
> +{
> + int ret;
> +
> + ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, page);
> + if (ret < 0)
> + return ret;
> +
> + ret = i2c_smbus_read_word_data(client, reg);
> + if (ret < 0)
> + return ret;
> +
> + /*
> + * Obtain vout scale from the register MFR_VOUT_LOOP_CTRL, bits 15-14,bit 13.
> + * If MFR_VOUT_LOOP_CTRL[13] = 1, the vout scale is below:
> + * 2.5mV/LSB
> + * If MFR_VOUT_LOOP_CTRL[13] = 0, the vout scale is decided by
> + * MFR_VOUT_LOOP_CTRL[15:14]:
> + * 00b - 6.25mV/LSB, 01b - 5mV/LSB, 10b - 2mV/LSB, 11b - 1mV
> + */
> + if (ret & GENMASK(13, 13)) {
> + data->info.m[PSC_VOLTAGE_OUT] = 4;
> + data->info.R[PSC_VOLTAGE_OUT] = -1;
> + data->info.b[PSC_VOLTAGE_OUT] = 0;
> + } else {
> + ret = (ret & GENMASK(15, 14)) >> 14;
Why not FIELD_GET() ?
> + if (ret == 0) {
> + data->info.m[PSC_VOLTAGE_OUT] = 16;
> + data->info.R[PSC_VOLTAGE_OUT] = -2;
> + data->info.b[PSC_VOLTAGE_OUT] = 0;
> + } else if (ret == 1) {
> + data->info.m[PSC_VOLTAGE_OUT] = 2;
> + data->info.R[PSC_VOLTAGE_OUT] = -1;
> + data->info.b[PSC_VOLTAGE_OUT] = 0;
> + } else if (ret == 2) {
> + data->info.m[PSC_VOLTAGE_OUT] = 5;
> + data->info.R[PSC_VOLTAGE_OUT] = -1;
> + data->info.b[PSC_VOLTAGE_OUT] = 0;
> + } else {
> + data->info.m[PSC_VOLTAGE_OUT] = 1;
> + data->info.R[PSC_VOLTAGE_OUT] = 0;
> + data->info.b[PSC_VOLTAGE_OUT] = 0;
> + }
> + }
> +
> + return 0;
> +}
> +
> +static int
> +mp2891_identify_rails_vout_scale(struct i2c_client *client, struct mp2891_data *data)
> +{
> + int ret;
> +
> + /* Identify vout scale from register MFR_VOUT_LOOP_CTRL. */
Useless comment.
> + /* Identify vout scale for rail 1. */
> + ret = mp2891_identify_vout_scale(client, data, MFR_VOUT_LOOP_CTRL, 0);
> + if (ret < 0)
> + return ret;
> +
> + /* Identify vout scale for rail 2. */
> + ret = mp2891_identify_vout_scale(client, data, MFR_VOUT_LOOP_CTRL, 1);
Passing the register to this function is useless. Just use the register directly
in mp2891_identify_vout_scale().
> +
> + return ret;
> +}
> +
> +static struct pmbus_driver_info mp2891_info = {
> + .pages = MP2891_PAGE_NUM,
> + .format[PSC_VOLTAGE_IN] = linear,
> + .format[PSC_CURRENT_IN] = linear,
> + .format[PSC_CURRENT_OUT] = linear,
> + .format[PSC_TEMPERATURE] = linear,
> + .format[PSC_POWER] = linear,
> + .format[PSC_VOLTAGE_OUT] = direct,
> +
> + .func[0] = MP2891_RAIL1_FUNC,
> + .func[1] = MP2891_RAIL2_FUNC,
> + .read_word_data = mp2891_read_word_data,
> + .read_byte_data = mp2891_read_byte_data,
> +};
> +
> +static int mp2891_probe(struct i2c_client *client)
> +{
> + struct pmbus_driver_info *info;
> + struct mp2891_data *data;
> + int ret;
> +
> + data = devm_kzalloc(&client->dev, sizeof(struct mp2891_data), GFP_KERNEL);
> + if (!data)
> + return -ENOMEM;
> +
> + memcpy(&data->info, &mp2891_info, sizeof(*info));
> + info = &data->info;
> +
> + /* Identify vout scale per rail. */
> + ret = mp2891_identify_rails_vout_scale(client, data);
> + if (ret < 0)
> + return ret;
> +
Why not use the identify() callback instead ?
> + return pmbus_do_probe(client, info);
> +}
> +
> +static const struct i2c_device_id mp2891_id[] = {
> + {"mp2891", 0},
> + {}
> +};
> +MODULE_DEVICE_TABLE(i2c, mp2891_id);
> +
> +static const struct of_device_id __maybe_unused mp2891_of_match[] = {
> + {.compatible = "mps,mp2891"},
> + {}
> +};
> +MODULE_DEVICE_TABLE(of, mp2891_of_match);
> +
> +static struct i2c_driver mp2891_driver = {
> + .driver = {
> + .name = "mp2891",
> + .of_match_table = mp2891_of_match,
> + },
> + .probe = mp2891_probe,
> + .id_table = mp2891_id,
> +};
> +
> +module_i2c_driver(mp2891_driver);
> +
> +MODULE_AUTHOR("Noah Wang <noahwang.wang@...look.com>");
> +MODULE_DESCRIPTION("PMBus driver for MPS MP2891 device");
drop "device"
> +MODULE_LICENSE("GPL");
> +MODULE_IMPORT_NS(PMBUS);
> --
> 2.25.1
>
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