Re: [PATCH 00/10] spi: Add driver to support AMD eSPI controller

[Mark Brown]

On Wed, Mar 26, 2025 at 03:25:21PM +0530, Rangoju, Raju wrote:
> On 3/17/2025 7:44 PM, Mark Brown wrote:

> > I see nothing in this series that registers a SPI controller with the
> > SPI core.  You need to use the standard frameworks the kernel offers to
> > provide standard functionality.

> The AMD SPI controller hardware has only the chip select line enabled, which
> is connected to the EC slave in AMD EMB platforms. Currently, there is no
> support from the slave device to register as an SPI slave device with the
> SPI framework and provide SPI communication.

> For this reason, the AMD eSPI driver is designed to handle device
> initialization itself and provide a character device file as an interface
> with user space for dynamic interaction and configurations.

If you want to ignore the SPI subsystem and just write a driver for your
embedded controller then you should put the driver in the subsystem or
subsystems for that embedded controller (possibly MFD if it does a bunch
of things), not SPI.  Even if there is no flexibility you may still want
to have the controller side in the SPI subsystem in order to help with
reuse with different controller/EC combinations but if you're going that
way you need to use the SPI subsystem.

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