linux-kernel - Re: [PATCH 3/5] spi: dw-mmio: add MSCC Ocelot support

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Date:   Wed, 18 Jul 2018 00:34:37 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc:     Mark Brown <broonie@...nel.org>, James Hogan <jhogan@...nel.org>,
        Paul Burton <paul.burton@...s.com>,
        linux-spi <linux-spi@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux MIPS Mailing List <linux-mips@...ux-mips.org>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Allan Nielsen <allan.nielsen@...rosemi.com>,
        Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH 3/5] spi: dw-mmio: add MSCC Ocelot support

On Tue, Jul 17, 2018 at 5:23 PM, Alexandre Belloni
<alexandre.belloni@...tlin.com> wrote:
> Because the SPI controller deasserts the chip select when the TX fifo is
> empty (which may happen in the middle of a transfer), the CS should be
> handled by linux. Unfortunately, some or all of the first four chip
> selects are not muxable as GPIOs, depending on the SoC.
>
> There is a way to bitbang those pins by using the SPI boot controller so
> use it to set the chip selects.
>
> At init time, it is also necessary to give control of the SPI interface to
> the Designware IP.

> +       ret = dw_spi_mscc_init(pdev, dwsmmio);
> +       if (ret)
> +               goto out;

> +       { .compatible = "mscc,ocelot-spi", .data = dw_spi_mscc_init},

Looks like you were thinking about something like

init_func = device_get_match_data(...);
if (init_func) {
 ret = init_func();
 if (ret)
   return ret;
}

?

-- 
With Best Regards,
Andy Shevchenko