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Message-ID: <84782418-958c-4477-a9d1-e1eb2714b225@roeck-us.net>
Date: Fri, 10 Nov 2023 07:34:46 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Peter Yin <peteryin.openbmc@...il.com>, patrick@...cx.xyz,
Jean Delvare <jdelvare@...e.com>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>,
Jonathan Corbet <corbet@....net>, linux-hwmon@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-doc@...r.kernel.org
Subject: Re: [PATCH v2 2/2] hwmon: (pmbus) Add support for MPS Multi-phase
mp5990
On 11/8/23 20:48, Peter Yin wrote:
> Add support for mp5990 device from Monolithic Power Systems, Inc. (MPS)
> vendor. This is a Hot-Swap Controller.
>
> Signed-off-by: Peter Yin <peteryin.openbmc@...il.com>
> ---
> Documentation/hwmon/index.rst | 1 +
> Documentation/hwmon/mp5990.rst | 84 +++++++++++++++++++++++++++++++++
> drivers/hwmon/pmbus/Kconfig | 9 ++++
> drivers/hwmon/pmbus/Makefile | 1 +
> drivers/hwmon/pmbus/mp5990.c | 86 ++++++++++++++++++++++++++++++++++
> 5 files changed, 181 insertions(+)
> create mode 100644 Documentation/hwmon/mp5990.rst
> create mode 100644 drivers/hwmon/pmbus/mp5990.c
>
> diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
> index 042e1cf9501b..8c70e10fc795 100644
> --- a/Documentation/hwmon/index.rst
> +++ b/Documentation/hwmon/index.rst
> @@ -157,6 +157,7 @@ Hardware Monitoring Kernel Drivers
> mp2888
> mp2975
> mp5023
> + mp5990
> nct6683
> nct6775
> nct7802
> diff --git a/Documentation/hwmon/mp5990.rst b/Documentation/hwmon/mp5990.rst
> new file mode 100644
> index 000000000000..d2da0f767530
> --- /dev/null
> +++ b/Documentation/hwmon/mp5990.rst
> @@ -0,0 +1,84 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +Kernel driver mp5990
> +====================
> +
> +Supported chips:
> +
> + * MPS MP5990
> +
> + Prefix: 'mp5990'
> +
> + * Datasheet
> +
> + Publicly available at the MPS website : https://www.monolithicpower.com/en/mp5990.html
> +
> +Author:
> +
> + Peter Yin <peteryin.openbmc@...il.com>
> +
> +Description
> +-----------
> +
> +This driver implements support for Monolithic Power Systems, Inc. (MPS)
> +MP5990 Hot-Swap Controller.
> +
> +Device compliant with:
> +
> +- PMBus rev 1.3 interface.
> +
> +Device supports direct format for reading input voltage, output voltage,
> +output current, input power and temperature.
> +
The device also supports linear mode according to its datasheet.
> +The driver exports the following attributes via the 'sysfs' files
> +for input voltage:
> +
> +**in1_input**
> +
> +**in1_label**
> +
> +**in1_max**
> +
> +**in1_max_alarm**
> +
> +**in1_min**
> +
> +**in1_min_alarm**
> +
> +The driver provides the following attributes for output voltage:
> +
> +**in2_input**
> +
> +**in2_label**
> +
> +**in2_alarm**
> +
> +The driver provides the following attributes for output current:
> +
> +**curr1_input**
> +
> +**curr1_label**
> +
> +**curr1_alarm**
> +
> +**curr1_max**
> +
> +The driver provides the following attributes for input power:
> +
> +**power1_input**
> +
> +**power1_label**
> +
> +**power1_alarm**
> +
> +The driver provides the following attributes for temperature:
> +
> +**temp1_input**
> +
> +**temp1_max**
> +
> +**temp1_max_alarm**
> +
> +**temp1_crit**
> +
> +**temp1_crit_alarm**
> diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
> index 270b6336b76d..65a116f7744d 100644
> --- a/drivers/hwmon/pmbus/Kconfig
> +++ b/drivers/hwmon/pmbus/Kconfig
> @@ -326,6 +326,15 @@ config SENSORS_MP5023
> This driver can also be built as a module. If so, the module will
> be called mp5023.
>
> +config SENSORS_MP5990
> + tristate "MPS MP5990"
> + help
> + If you say yes here you get hardware monitoring support for MPS
> + MP5990.
> +
> + This driver can also be built as a module. If so, the module will
> + be called mp5990.
> +
> 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 84ee960a6c2d..212d9ca0acc9 100644
> --- a/drivers/hwmon/pmbus/Makefile
> +++ b/drivers/hwmon/pmbus/Makefile
> @@ -35,6 +35,7 @@ obj-$(CONFIG_SENSORS_MAX8688) += max8688.o
> obj-$(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_MPQ7932) += mpq7932.o
> obj-$(CONFIG_SENSORS_PLI1209BC) += pli1209bc.o
> obj-$(CONFIG_SENSORS_PM6764TR) += pm6764tr.o
> diff --git a/drivers/hwmon/pmbus/mp5990.c b/drivers/hwmon/pmbus/mp5990.c
> new file mode 100644
> index 000000000000..fb3ac9c5d44e
> --- /dev/null
> +++ b/drivers/hwmon/pmbus/mp5990.c
> @@ -0,0 +1,86 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Driver for MPS MP5990 Hot-Swap Controller
> + */
> +
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/pmbus.h>
Not used in this driver.
> +#include "pmbus.h"
> +
> +static int mp5990_read_byte_data(struct i2c_client *client, int page, int reg)
> +{
> + switch (reg) {
> + case PMBUS_VOUT_MODE:
> + /* The datasheet does not support the VOUT command,
Standard multi-line comments, please. This is not the networking subsystem.
> + * but the device responds with a default value of 0x17.
> + * In the standard, 0x17 represents linear mode. However,
> + * for the MP5990, the VOUT linear mode is linear11, not linear16.
> + * Therefore, we should enforce the VOUT in the direct format.
> + */
> + return PB_VOUT_MODE_DIRECT;
This doesn't take into account that the reporting mode is set in
EFUSE_CFG bit 9 (RPT_FORMAT). If the chip is configured to report its data
in linear mode, all readings will be wrong if the exponent is != 0 and
for negative values.
The driver could enforce direct mode by explicitly configuring EFUSE_CFG,
but that is not guaranteed to work because the chip could be write
protected. It would be necessary to disable write protection first,
making this a bit complicated. Alternatively, the reading of VOUT could
be adjusted in linear mode to linear16 if the chip is configured to
report data in linear mode. I would personally prefer this solution.
Either case, this needs to be handled.
Guenter
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