linux-kernel - Re: [PATCH 1/2] hwmon: add Delta AHE-50DC fan control module driver

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Message-ID: <28719505-ace1-bb04-bbc2-043c56b0db7d@roeck-us.net>
Date:   Mon, 6 Dec 2021 15:02:49 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Zev Weiss <zev@...ilderbeest.net>, linux-hwmon@...r.kernel.org
Cc:     Jean Delvare <jdelvare@...e.com>, openbmc@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] hwmon: add Delta AHE-50DC fan control module driver

On 12/6/21 2:44 PM, Zev Weiss wrote:
> This device is an integrated module of the Delta AHE-50DC Open19 power
> shelf.  For lack of proper documentation, this driver has been developed
> referencing an existing (GPL) driver that was included in a code release
> from LinkedIn [1].  It provides four fan speeds, four temperatures, and
> one voltage reading, as well as a handful of warning and fault
> indicators.
> 
> [1] https://github.com/linkedin/o19-bmc-firmware/blob/master/meta-openbmc/meta-linkedin/meta-deltapower/recipes-kernel/fancontrol-mod/files/fancontrol.c
> 
> Signed-off-by: Zev Weiss <zev@...ilderbeest.net>
> ---

[ ... ]

> +
> +static const u8 AHE50DC_FAN_TEMP_REGS[] = { 0x8d, 0x8e, 0x8f, 0xd0 };
> +static const u8 AHE50DC_FAN_SPEED_REGS[] = { 0x90, 0x91, 0x92, 0x93 };
> +static const u8 AHE50DC_FAN_FAN_STATUS_REGS[] = { 0x81, 0x82 };
> +#define AHE50DC_FAN_VIN_REG 0x88
> +#define AHE50DC_FAN_CHIP_STATUS_REG 0x79

PMBus registers:

	PMBUS_STATUS_WORD               = 0x79,

	PMBUS_STATUS_FAN_12             = 0x81,
	PMBUS_STATUS_FAN_34             = 0x82,

	PMBUS_READ_VIN                  = 0x88,

         PMBUS_READ_TEMPERATURE_1        = 0x8D,
         PMBUS_READ_TEMPERATURE_2        = 0x8E,
         PMBUS_READ_TEMPERATURE_3        = 0x8F,
         PMBUS_READ_FAN_SPEED_1          = 0x90,
         PMBUS_READ_FAN_SPEED_2          = 0x91,
         PMBUS_READ_FAN_SPEED_3          = 0x92,
         PMBUS_READ_FAN_SPEED_4          = 0x93,

This is quite obviously a PMBus device. Why not use the PMBus driver ?

Guenter