| From | Andy Shevchenko <> | Date | Tue, 14 Jun 2022 13:10:20 +0200 | Subject | Re: [PATCH v5 12/15] spi: dw: Add support for AMD Pensando Elba SoC |
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On Mon, Jun 13, 2022 at 9:57 PM Brad Larson <brad@pensando.io> wrote: > > From: Brad Larson <blarson@amd.com> > > The AMD Pensando Elba SoC includes a DW apb_ssi v4 controller > with device specific chip-select control. The Elba SoC > provides four chip-selects where the native DW IP supports > two chip-selects. The Elba DW_SPI instance has two native > CS signals that are always overridden.
...
> +/* > + * Elba SoC does not use ssi, pin override is used for cs 0,1 and > + * gpios for cs 2,3 as defined in the device tree. > + * > + * cs: | 1 0 > + * bit: |---3-------2-------1-------0 > + * | cs1 cs1_ovr cs0 cs0_ovr > + */
> +#define ELBA_SPICS_SHIFT(cs) (2 * (cs))
Useless.It takes much more than simply multiplying each time in two macros. Also see below.
> +#define ELBA_SPICS_MASK(cs) (0x3 << ELBA_SPICS_SHIFT(cs))
(GENMASK(1, 0) << ((cs) << 1))
Or ((cs) * 2) to show that it takes 2 bits and not two times of CS',
> +#define ELBA_SPICS_SET(cs, val) \ > + ((((val) << 1) | 0x1) << ELBA_SPICS_SHIFT(cs))
BIT(0)
So the main point is to use GENMASK() and BIT() the rest is up to you.
-- With Best Regards, Andy Shevchenko
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