linux-kernel - Re: [PATCH 4/4] spi: dw: Add Synopsys Component version reading and parsing

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Message-ID: <CAHp75VeEaj6zNtdRF65t_xriWe=Agx3WuW8tw6XZzBHCXtTgmw@mail.gmail.com>
Date:   Fri, 12 Nov 2021 23:27:05 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Serge Semin <Sergey.Semin@...kalelectronics.ru>
Cc:     Serge Semin <fancer.lancer@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Nandhini Srikandan <nandhini.srikandan@...el.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Andy Shevchenko <andy@...nel.org>,
        linux-spi <linux-spi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] spi: dw: Add Synopsys Component version reading and parsing

On Fri, Nov 12, 2021 at 10:52 PM Serge Semin
<Sergey.Semin@...kalelectronics.ru> wrote:
>
> Each Synopsys DWC SSI controller is equipped with a Synopsys Component
> version register, which encodes a version ID of an IP-core the
> controller has been synthesized from. That can be useful in future for the
> version-based conditional features implementation in the driver.
>
> Note the component version is encoded as an ASCII string so we need to
> convert it from the string to a normal unsigned integer to be easily used
> then in the driver statements.
>
> Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
> ---
>  drivers/spi/spi-dw-core.c | 18 ++++++++++++++++++
>  drivers/spi/spi-dw.h      |  1 +
>  2 files changed, 19 insertions(+)
>
> diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c
> index b4cbcd38eaba..1766a29ca790 100644
> --- a/drivers/spi/spi-dw-core.c
> +++ b/drivers/spi/spi-dw-core.c
> @@ -823,6 +823,24 @@ static void dw_spi_hw_init(struct device *dev, struct dw_spi *dws)
>  {
>         dw_spi_reset_chip(dws);
>
> +       /*
> +        * Retrieve the Synopsys component version if it hasn't been specified
> +        * by the platform. Note the CoreKit version ID is encoded as a 4bytes
> +        * ASCII string enclosed with '*' symbol.
> +        */
> +       if (!dws->ver) {
> +               u32 comp;
> +
> +               comp = dw_readl(dws, DW_SPI_VERSION);
> +               dws->ver = (DW_SPI_GET_BYTE(comp, 3) - '0') * 100;
> +               dws->ver += (DW_SPI_GET_BYTE(comp, 2) - '0') * 10;
> +               dws->ver += (DW_SPI_GET_BYTE(comp, 1) - '0');
> +
> +               dev_dbg(dev, "Synopsys DWC%sSSI v%u.%02u\n",
> +                       (dws->caps & DW_SPI_CAP_DWC_HSSI) ? " " : " APB ",
> +                       dws->ver / 100, dws->ver % 100);

Oh là là, first you multiply then you divide in the same piece of code!
What's wrong with fourcc (and thus keep it in ver filed as is) ? (Also
we have %p4cc)

> +       }
> +
>         /*
>          * Try to detect the FIFO depth if not set by interface driver,
>          * the depth could be from 2 to 256 from HW spec
> diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
> index 634085eadad1..d06857d8d173 100644
> --- a/drivers/spi/spi-dw.h
> +++ b/drivers/spi/spi-dw.h
> @@ -149,6 +149,7 @@ struct dw_spi {
>         u32                     max_mem_freq;   /* max mem-ops bus freq */
>         u32                     max_freq;       /* max bus freq supported */
>
> +       u32                     ver;            /* Synopsys component version */
>         u32                     caps;           /* DW SPI capabilities */
>
>         u32                     reg_io_width;   /* DR I/O width in bytes */
> --
> 2.33.0
>


-- 
With Best Regards,
Andy Shevchenko