Re: [PATCH V8 1/3] mfd: Add support for UP board CPLD/FPGA

[Krzysztof Kozlowski <krzk@kernel.org>]

On 28/12/2023 16:15, larry.lai wrote:
> The UP Squared board <http://www.upboard.com> implements certain
> features (pin control, onboard LEDs or CEC) through an on-board CPLD/FPGA.
> 
> This driver implements the line protocol to read and write registers
> from the FPGA through regmap. The register address map is also included.
> 

...

> +#define FIRMWARE_ID_BUILD_OFFSET	12
> +#define FIRMWARE_ID_MAJOR_OFFSET	8
> +#define FIRMWARE_ID_MINOR_OFFSET	4
> +#define FIRMWARE_ID_PATCH_OFFSET	0
> +#define FIRMWARE_ID_MASK		GENMASK(3, 0)
> +
> +/*
> + * read CPLD register on custom protocol
> + * send clock and addr bit in strobe and datain pins then read from dataout pin
> + */
> +static int upboard_cpld_read(void *context, unsigned int reg, unsigned int *val)
> +{
> +	struct upboard_fpga * const fpga = context;

This const does not make sense. Drop it. Unless you wanted to say
something else, like struct is not modified, but then please read C
tutorials. This applies to all your three patches.

Best regards,
Krzysztof