linux-kernel - Re: [PATCH v3 3/3] Documentation: hwmon: New information for DA9063

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Message-ID: <f0c0fef4-9e5a-df23-bfbb-db490bc591c0@roeck-us.net>
Date:   Sat, 10 Jul 2021 09:17:40 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Vincent Pelletier <plr.vincent@...il.com>,
        Jean Delvare <jdelvare@...e.com>,
        Jonathan Corbet <corbet@....net>,
        Support Opensource <support.opensource@...semi.com>,
        Lee Jones <lee.jones@...aro.org>, linux-hwmon@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Opensource [Steve Twiss]" <stwiss.opensource@...semi.com>
Subject: Re: [PATCH v3 3/3] Documentation: hwmon: New information for DA9063

On 7/7/21 6:25 AM, Vincent Pelletier wrote:
> From: "Opensource [Steve Twiss]" <stwiss.opensource@...semi.com>
> 
> Addition of HWMON documentation for the DA9063 driver.
> 
> Signed-off-by: Opensource [Steve Twiss] <stwiss.opensource@...semi.com>
> 
> Updated temperature formula, as of datasheet rev 2.3.
> Converted to ReStructuredText.
> 
> Signed-off-by: Vincent Pelletier <plr.vincent@...il.com>
> ---
> Changes in v3:
> - Reference added to index.rst
> 
> Changes in v2:
> - ReST-ified
> 
> Originally submitted by Steve Twiss in 2014:
>    https://marc.info/?l=linux-kernel&m=139560868209856&w=2
> 
>   Documentation/hwmon/da9063.rst | 73 ++++++++++++++++++++++++++++++++++
>   Documentation/hwmon/index.rst  |  1 +
>   2 files changed, 74 insertions(+)
>   create mode 100644 Documentation/hwmon/da9063.rst
> 
> diff --git a/Documentation/hwmon/da9063.rst b/Documentation/hwmon/da9063.rst
> new file mode 100644
> index 000000000000..aae69c58a5d6
> --- /dev/null
> +++ b/Documentation/hwmon/da9063.rst
> @@ -0,0 +1,73 @@
> +Kernel driver da9063-hwmon
> +==========================
> +
> +Supported chips:
> +
> +  * Dialog Semiconductor DA9063 PMIC
> +
> +    Prefix: 'da9063'
> +
> +    Datasheet: Publicly available at the Dialog Semiconductor website:
> +
> +	http://www.dialog-semiconductor.com/products/power-management/DA9063
> +
> +Authors:
> +	- S Twiss <stwiss.opensource@...semi.com>
> +	- Vincent Pelletier <plr.vincent@...il.com>
> +
> +Description
> +-----------
> +
> +The DA9063 PMIC provides a general purpose ADC with 10 bits of resolution.
> +It uses track and hold circuitry with an analogue input multiplexer which
> +allows the conversion of up to 9 different inputs:
> +
> +- Channel  0: VSYS_RES	measurement of the system VDD (2.5 - 5.5V)
> +- Channel  1: ADCIN1_RES	high impedance input (0 - 2.5V)
> +- Channel  2: ADCIN2_RES	high impedance input (0 - 2.5V)
> +- Channel  3: ADCIN3_RES	high impedance input (0 - 2.5V)
> +- Channel  4: Tjunc	measurement of internal temperature sensor
> +- Channel  5: VBBAT	measurement of the backup battery voltage (0 - 5.0V)
> +- Channel  6: N/A	Reserved
> +- Channel  7: N/A	Reserved
> +- Channel  8: MON1_RES	group 1 internal regulators voltage (0 - 5.0V)
> +- Channel  9: MON2_RES	group 2 internal regulators voltage (0 - 5.0V)
> +- Channel 10: MON3_RES	group 3 internal regulators voltage (0 - 5.0V)
> +
> +The MUX selects from and isolates the 9 inputs and presents the channel to
> +be measured to the ADC input. When selected, an input amplifier on the VSYS
> +channel subtracts the VDDCORE reference voltage and scales the signal to the
> +correct value for the ADC.
> +
> +The analog ADC includes current sources at ADC_IN1, ADC_IN2 and ADC_IN3 to
> +support resistive measurements.
> +
> +Channels 1, 2 and 3 current source capability can be set through the ADC
> +thresholds ADC_CFG register and values for ADCIN1_CUR, ADCIN2_CUR and
> +ADCIN3_CUR. Settings for ADCIN1_CUR and ADCIN2_CUR are 1.0, 2.0, 10 and
> +40 micro Amps. The setting for ADCIN3_CUR is 10 micro Amps.
> +
> +Voltage Monitoring
> +------------------
> +
> +The manual measurement allows monitoring of the system voltage VSYS, the
> +auxiliary channels ADCIN1, ADCIN2 and ADCIN3, and a VBBAT measurement of
> +the backup battery voltage (0 - 5.0V). The manual measurements store 10
> +bits of ADC resolution.
> +
> +The manual ADC measurements attributes described above are supported by
> +the driver.
> +

Not really. The driver only reports VSYS and VBBAT plus the temperature,
so this documentation is very misleading. Please provide a list of supported
attributes and their association to the ADC channels.

> +The automatic ADC measurement is not supported by the driver.
> +
> +Temperature Monitoring
> +----------------------
> +
> +Temperatures are sampled by a 10 bit ADC.  Junction temperatures
> +are monitored by the ADC channels.
> +
> +The junction temperature is calculated:
> +
> +	Degrees celsius = -0.398 * (ADC_RES - T_OFFSET) + 330;
> +
> +The junction temperature attribute is supported by the driver.
> diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
> index 9ed60fa84cbe..b3aba6525157 100644
> --- a/Documentation/hwmon/index.rst
> +++ b/Documentation/hwmon/index.rst
> @@ -51,6 +51,7 @@ Hardware Monitoring Kernel Drivers
>      corsair-psu
>      da9052
>      da9055
> +   da9063
>      dell-smm-hwmon
>      dme1737
>      drivetemp
>