Re: [PATCH] iio: documentation: Add out_altvoltage and friends

[Michael Hennerich <michael.hennerich@analog.com>]

On 05/02/2012 04:36 PM, Jonathan Cameron wrote:
> On 5/2/2012 12:24 PM, michael.hennerich@analog.com wrote:
>> From: Michael Hennerich<michael.hennerich@analog.com>
>>
>> Continuous frequency/clock generating devices, such as DDSs or PLLs
>> should use out_altvolatge.
>>
>> Signed-off-by: Michael Hennerich<michael.hennerich@analog.com>
>> ---
>>    Documentation/ABI/testing/sysfs-bus-iio |   31 +++++++++++++++++++++++++++++++
>>    1 files changed, 31 insertions(+), 0 deletions(-)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
>> index 2ce4dad..f757a30 100644
>> --- a/Documentation/ABI/testing/sysfs-bus-iio
>> +++ b/Documentation/ABI/testing/sysfs-bus-iio
>> @@ -219,6 +219,7 @@ What:             /sys/bus/iio/devices/iio:deviceX/in_voltageY_scale
>>    What:               /sys/bus/iio/devices/iio:deviceX/in_voltageY_supply_scale
>>    What:               /sys/bus/iio/devices/iio:deviceX/in_voltage_scale
>>    What:               /sys/bus/iio/devices/iio:deviceX/out_voltageY_scale
>> +What:                /sys/bus/iio/devices/iio:deviceX/out_altvoltageY_scale
>>    What:               /sys/bus/iio/devices/iio:deviceX/in_accel_scale
>>    What:               /sys/bus/iio/devices/iio:deviceX/in_accel_peak_scale
>>    What:               /sys/bus/iio/devices/iio:deviceX/in_anglvel_scale
>> @@ -273,6 +274,7 @@ What:             /sys/bus/iio/devices/iio:deviceX/in_accel_scale_available
>>    What:               /sys/.../iio:deviceX/in_voltageX_scale_available
>>    What:               /sys/.../iio:deviceX/in_voltage-voltage_scale_available
>>    What:               /sys/.../iio:deviceX/out_voltageX_scale_available
>> +What:                /sys/.../iio:deviceX/out_altvoltageX_scale_available
>>    What:               /sys/.../iio:deviceX/in_capacitance_scale_available
>>    KernelVersion:      2.635
>>    Contact:    linux-iio@vger.kernel.org
>> @@ -291,14 +293,19 @@ Description:
>>                gives the 3dB frequency of the filter in Hz.
>>
>>    What:               /sys/bus/iio/devices/iio:deviceX/out_voltageY_raw
>> +What:                /sys/bus/iio/devices/iio:deviceX/out_altvoltageY_raw
>>    KernelVersion:      2.6.37
>>    Contact:    linux-iio@vger.kernel.org
>>    Description:
>>                Raw (unscaled, no bias etc.) output voltage for
>>                channel Y.  The number must always be specified and
>>                unique if the output corresponds to a single channel.
>> +             While DAC like devices typically use out_voltage,
>> +             a continuous frequency generating device, such as
>> +             a DDS or PLL should use out_altvolatge.
>>
>>    What:               /sys/bus/iio/devices/iio:deviceX/out_voltageY&Z_raw
>> +What:                /sys/bus/iio/devices/iio:deviceX/out_altvoltageY&Z_raw
>>    KernelVersion:      2.6.37
>>    Contact:    linux-iio@vger.kernel.org
>>    Description:
>> @@ -309,6 +316,8 @@ Description:
>>
>>    What:               /sys/bus/iio/devices/iio:deviceX/out_voltageY_powerdown_mode
>>    What:               /sys/bus/iio/devices/iio:deviceX/out_voltage_powerdown_mode
>> +What:                /sys/bus/iio/devices/iio:deviceX/out_altvoltageY_powerdown_mode
>> +What:                /sys/bus/iio/devices/iio:deviceX/out_altvoltage_powerdown_mode
>>    KernelVersion:      2.6.38
>>    Contact:    linux-iio@vger.kernel.org
>>    Description:
>> @@ -323,6 +332,8 @@ Description:
>>
>>    What:               /sys/.../iio:deviceX/out_votlageY_powerdown_mode_available
>>    What:               /sys/.../iio:deviceX/out_voltage_powerdown_mode_available
>> +What:                /sys/.../iio:deviceX/out_altvotlageY_powerdown_mode_available
>> +What:                /sys/.../iio:deviceX/out_altvoltage_powerdown_mode_available
>>    KernelVersion:      2.6.38
>>    Contact:    linux-iio@vger.kernel.org
>>    Description:
>> @@ -331,6 +342,8 @@ Description:
>>
>>    What:               /sys/bus/iio/devices/iio:deviceX/out_voltageY_powerdown
>>    What:               /sys/bus/iio/devices/iio:deviceX/out_voltage_powerdown
>> +What:                /sys/bus/iio/devices/iio:deviceX/out_altvoltageY_powerdown
>> +What:                /sys/bus/iio/devices/iio:deviceX/out_altvoltage_powerdown
>>    KernelVersion:      2.6.38
>>    Contact:    linux-iio@vger.kernel.org
>>    Description:
>> @@ -339,6 +352,24 @@ Description:
>>                normal operation. Y may be suppressed if all outputs are
>>                controlled together.
>>
>> +What:                /sys/bus/iio/devices/iio:deviceX/out_altvoltageY_frequency
>> +KernelVersion:       3.4.0
>> +Contact:     linux-iio@vger.kernel.org
>> +Description:
>> +             Output frequency for channel Y in Hz. The number must always be
>> +             specified and unique if the output corresponds to a single
>> +             channel.
>> +
>> +What:                /sys/bus/iio/devices/iio:deviceX/out_altvoltageY_phase
>> +KernelVersion:       3.4.0
>> +Contact:     linux-iio@vger.kernel.org
>> +Description:
>> +             Phase in radians of one frequency/clock output Y
>> +             (out_altvoltageY) relative to another frequency/clock output
>> +             (out_altvoltageZ) of the device X. The number must always be
>> +             specified and unique if the output corresponds to a single
>> +             channel.
>> +
> Do we need a way of specifying which channel is channel z?  e.g. what
> this is relative to?  Or do
> we always assume it is relative to the channel 0?
Right now it's assumed it's relative to a channel that sets
phase to 0.

The device in mind is a clock distribution IC featuring 14 channels.
Each channel can be given a phase offset. When the device is put
into SYNC, either a external supplied pulse, or by writing an
sysfs attribute, the state machine starts the channels with
it's dedicated phase offset.

Side questions. Radian is a SI derived unit, however dealing with
fractions and multiples of PI is a bit suboptimal within the kernel.

Do you mind if we make phase use degrees or grads?

>
> Rest are fine.
>>    What:               /sys/bus/iio/devices/iio:deviceX/events
>>    KernelVersion:      2.6.35
>>    Contact:    linux-iio@vger.kernel.org
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-- 
Greetings,
Michael

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