[U-Boot Patch v2 2/4] spi: fu540: add claim and release method to spi-sifive.c

[Bin Meng]

Hi Sagar,

On Wed, Jan 29, 2020 at 2:02 AM Sagar Shrikant Kadam
<sagar.kadam at sifive.com> wrote:
>
> Add missing bus claim/release method to spi driver for HiFive
> Unleashed, and handle num_cs generously so that it generates
> an error if invalid cs number is passed to sf probe.

Is adding the claim/release method the fix to the weird "sf probe
0:2/4/6/8" issue?

>
> Signed-off-by: Sagar Shrikant Kadam <sagar.kadam at sifive.com>
> ---
>  drivers/spi/spi-sifive.c | 36 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 36 insertions(+)
>
> diff --git a/drivers/spi/spi-sifive.c b/drivers/spi/spi-sifive.c
> index 969bd4b..f990ad6 100644
> --- a/drivers/spi/spi-sifive.c
> +++ b/drivers/spi/spi-sifive.c
> @@ -186,6 +186,36 @@ static void sifive_spi_tx(struct sifive_spi *spi, const u8 *tx_ptr)
>         writel(tx_data, spi->regs + SIFIVE_SPI_REG_TXDATA);
>  }
>
> +static int sifive_spi_claim_bus(struct udevice *dev)
> +{
> +       int ret;
> +       struct udevice *bus = dev->parent;
> +       struct sifive_spi *spi = dev_get_priv(bus);
> +       struct dm_spi_slave_platdata *slave = dev_get_parent_platdata(dev);
> +
> +       if (!(slave->cs < spi->num_cs)) {

slave->cs >= spi->num_cs

But there is already check added recently in the spi-uclass driver, see below:

commit 7bacce524d48594dae399f9ee9280ab105f6c8cf
Author: Bin Meng <bmeng.cn at gmail.com>
Date:   Mon Sep 9 06:00:02 2019 -0700

    dm: spi: Check cs number before accessing slaves

    Add chip select number check in spi_find_chip_select().

    Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
    Tested-by: Jagan Teki <jagan at amarulasolutions.com> # SoPine

Adding check in the sifive spi driver seems to unnecessary. Could you
please confirm?

> +               printf("Invalid cs number = %d\n", slave->cs);
> +               return -EINVAL;
> +       }
> +
> +       sifive_spi_prep_device(spi, slave);
> +
> +       ret = sifive_spi_set_cs(spi, slave);
> +       if (ret)
> +               return ret;
> +
> +       return 0;
> +}
> +
> +static int sifive_spi_release_bus(struct udevice *dev)
> +{
> +       struct sifive_spi *spi = dev_get_priv(dev->parent);
> +
> +       sifive_spi_clear_cs(spi);
> +
> +       return 0;
> +}

What was done in the sifive_spi_claim_bus / sifive_spi_release_bus
seems to be already done in sifive_spi_xfer(). See flags testing
against SPI_XFER_BEGIN and SPI_XFER_END.

Could you please explain a little bit on why adding these 2 fixes things?

> +
>  static int sifive_spi_xfer(struct udevice *dev, unsigned int bitlen,
>                            const void *dout, void *din, unsigned long flags)
>  {
> @@ -345,6 +375,10 @@ static int sifive_spi_probe(struct udevice *bus)
>         /* init the sifive spi hw */
>         sifive_spi_init_hw(spi);
>
> +       /* Fetch number of chip selects from DT if present */
> +       ret = dev_read_u32_default(bus, "num-cs", spi->num_cs);
> +       spi->num_cs = ret;

spi->num_cs is already assigned a value in sifive_spi_init_hw(), Why
do we override the value using DT's?

> +
>         return 0;
>  }
>
> @@ -353,6 +387,8 @@ static const struct dm_spi_ops sifive_spi_ops = {
>         .set_speed      = sifive_spi_set_speed,
>         .set_mode       = sifive_spi_set_mode,
>         .cs_info        = sifive_spi_cs_info,
> +       .claim_bus      = sifive_spi_claim_bus,
> +       .release_bus    = sifive_spi_release_bus,
>  };
>
>  static const struct udevice_id sifive_spi_ids[] = {
> --

Regards,
Bin