[PATCH linux dev-5.4 1/3] fsi: aspeed: Support CFAM reset GPIO

[Andrew Jeffery]

On Fri, 24 Jul 2020, at 12:00, Joel Stanley wrote:
> Systems have a line for restting the remote CFAM. This is not part of
> the FSI master, but is associated with it, so it makes sense to include
> it in the master driver.
> 
> This exposes a sysfs interface to reset the cfam, abstracting away the
> direction and polarity of the GPIO, as well as the timing of the reset
> pulse. Userspace will be blocked until the reset pulse is finished.
> 
> The reset is hard coded to be in the range of (900, 1000) us. It was
> observed with a scope to regularly be just over 1ms.
> 
> If the device tree property is not preset the driver will silently
> continue.
> 
> Signed-off-by: Joel Stanley <joel at jms.id.au>

Reviewed-by: Andrew Jeffery <andrew at aj.id.au>