[PATCHv1 2/3] hwmon: Add documentation for g762 driver

[Guenter Roeck]

On Wed, Apr 24, 2013 at 12:06:08AM +0200, Arnaud Ebalard wrote:
> 
> Signed-off-by: Arnaud Ebalard <arno at natisbad.org>
> ---
>  Documentation/hwmon/g762 |   67 ++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 67 insertions(+)
>  create mode 100644 Documentation/hwmon/g762
> 
> diff --git a/Documentation/hwmon/g762 b/Documentation/hwmon/g762
> new file mode 100644
> index 0000000..5015829
> --- /dev/null
> +++ b/Documentation/hwmon/g762
> @@ -0,0 +1,67 @@
> +Kernel driver g762
> +==================
> +
> +This documentation is based on G760a one, GMT G762 datasheet available

G760a ? If this refers to Documentation/hwmon/g760a, I think it is just
confusing.

> +at http://natisbad.org/NAS/ref/GMT_EDS-762_763-080710-0.2.pdf (used
> +for the development of the driver) and sysfs bindings described in

I would hope that you used the data sheet for the driver ;), but that
information does not add much if any value here. I would suggest
to drop it. Just point to the data sheet.

> +Documentation/hwmon/sysfs-interface.
> +
> +The GMT G762 Fan Speed PWM Controller is connected directly to a fan
> +and performs closed-loop or open-loop control of the fan speed. Two
> +modes - PWM or linear - are supported by the device.
> +
> +The following entries are available to the user in a subdirectory of
> +/sys/bus/i2c/drivers/g762/ to control the operation of the device.
> +This can be done manually using the following entries but is usually
> +done via a userland daemon like fancontrol.
> +
> +Note that those entries do not provide ways to setup the specific
> +hardware characteristics of the system (reference clock, pulses per
> +fan revolution, ...); Those can be modified via devicetree bindings
> +documented in Documentation/devicetree/bindings/hwmon/g762.txt.
> +
> +
> +  fan1_target: set desired fan speed. This only makes sense in closed-loop
> +            fan speed control (i.e. when pwm1_enable is set to 2).
> +
> +  fan1_input: provide current fan rotation value in RPM as reported by
> +            the fan to the device.
> +
> +  fan1_div: fan clock divisor. Supported value are 1, 2, 4 and 8. Default
> +            value is 1.
> +
> +  fan1_gear_mode: fan gear mode. Supported values are 0, 1 and 2. Default
> +            value is 0. The value is a characteristic of the system
> +            and a higher value can be set for more precisely control
> +            fans with a high rotation speed. Note that this affects the
> +            measurable speed range, not the read value.
> +
This attribute no longer exists.

> +  fan1_fault: reports fan failure, i.e. no transition on fan gear pin for
> +            about 0.7s (if the fan is not voluntarily set off).
> +
> +  fan1_alarm: in closed-loop control mode, if fan RPM value is 25% out
> +            of the programmed value for over 6 seconds 'fan1_alarm' is
> +            set to 1.
> +
> +  pwm1: get or set PWM fan control value. This is an integer value
> +            between 0 and 255. 0 stops the fan, 255 makes it run at
> +            full speed.
> +
> +  pwm1_enable: set current fan speed control mode i.e. 1 for manual fan
> +            speed control (open-loop), 2 for automatic fan speed control
> +            (closed-loop).
> +
> +  pwm1_mode: set or get fan driving mode: 1 for PWM mode, 0 for linear
> +            mode. Default is linear mode.
> +
> +
> +In PWM mode ('pwm1_mode' set to 1), the fan speed is programmed either by
> +setting a value between 0 and 255 via 'pwm1' entry (0 stops the fan, 255
> +makes it run at full speed). This can also be done by passing the
> +expected RPM value via 'fan1_target'. Current fan speed value can be
> +retrieved via 'fan1_input'. This fan speed value is computed based on
> +the parameters associated with the physical characteristics of the
> +system: a reference clock source frequency, a number of pulses per fan
> +revolution, etc.
> +
> +Note that the driver will update its values at most once per second.
> -- 
> 1.7.10.4
> 
>