Re: [PATCH v0 1/1] spi: spi-rockchip: add support for spi slave_mode

[Emil Renner Berthing <emil.renner.berthing@xxxxxxxxx>]

Hi Chris,

On Fri, 8 May 2020 at 10:47, Chris Ruehl <chris.ruehl@xxxxxxxxxxxx> wrote:
>
> This patch aim to add spi slave mode support to the rockchip driver.
> Fix the wrong usage of num_cs set fix to ROCKCHIP_SPI_MAX_CS_NUM,
> instead use max_native_cs flag to set the limit of native chip-select.
> Enable use_gpio_descriptors to have cs_gpiod for gpio based chip-selects.
>
> Signed-off-by: Chris Ruehl <chris.ruehl@xxxxxxxxxxxx>
> ---
>  drivers/spi/spi-rockchip.c | 46 +++++++++++++++++++++++++++++++++-----
>  1 file changed, 41 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
> index 70ef63e0b6b8..9c1ff52c0f85 100644
> --- a/drivers/spi/spi-rockchip.c
> +++ b/drivers/spi/spi-rockchip.c
> @@ -183,6 +183,9 @@ struct rockchip_spi {
>         u8 rsd;
>
>         bool cs_asserted[ROCKCHIP_SPI_MAX_CS_NUM];
> +
> +       bool slave_mode;
> +       bool slave_abort;
>  };
>
>  static inline void spi_enable_chip(struct rockchip_spi *rs, bool enable)
> @@ -359,7 +362,7 @@ static void rockchip_spi_dma_rxcb(void *data)
>         struct rockchip_spi *rs = spi_master_get_devdata(master);
>         int state = atomic_fetch_andnot(RXDMA, &rs->state);
>
> -       if (state & TXDMA)
> +       if (state & TXDMA && !rs->slave_abort)
>                 return;
>
>         spi_enable_chip(rs, false);
> @@ -372,7 +375,7 @@ static void rockchip_spi_dma_txcb(void *data)
>         struct rockchip_spi *rs = spi_master_get_devdata(master);
>         int state = atomic_fetch_andnot(TXDMA, &rs->state);
>
> -       if (state & RXDMA)
> +       if (state & RXDMA && !rs->slave_abort)
>                 return;
>
>         /* Wait until the FIFO data completely. */
> @@ -466,6 +469,10 @@ static void rockchip_spi_config(struct rockchip_spi *rs,
>         u32 cr1;
>         u32 dmacr = 0;
>
> +       if (rs->slavemode)
> +               cr0 |= CR0_OPM_SLAVE << CR0_OPM_OFFSET;
> +       rs->slave_abort = false;
> +
>         cr0 |= rs->rsd << CR0_RSD_OFFSET;
>         cr0 |= (spi->mode & 0x3U) << CR0_SCPH_OFFSET;
>         if (spi->mode & SPI_LSB_FIRST)
> @@ -535,6 +542,16 @@ static size_t rockchip_spi_max_transfer_size(struct spi_device *spi)
>         return ROCKCHIP_SPI_MAX_TRANLEN;
>  }
>
> +static int rockchip_spi_slave_abort(struct spi_master *master)
> +{
> +       struct rockchip_spi *rs = spi_master_get_devdata(master);
> +
> +       rs->slave_abort = true;
> +       complete(master);
> +
> +       return 0;
> +}
> +
>  static int rockchip_spi_transfer_one(
>                 struct spi_master *master,
>                 struct spi_device *spi,
> @@ -589,14 +606,25 @@ static int rockchip_spi_probe(struct platform_device *pdev)
>         struct spi_master *master;
>         struct resource *mem;
>         u32 rsd_nsecs;
> +       bool slave_mode;
> +       u32 num_cs = 1;
> +
> +       slave_mode = of_property_read_bool(np, "spi-slave");
> +
> +       if (slave_mode)
> +               master = spi_alloc_slave(&pdev->dev,
> +                               sizeof(struct rockchip_spi));
> +       else
> +               master = spi_alloc_master(&pdev->dev,
> +                               sizeof(struct rockchip_spi));
>
> -       master = spi_alloc_master(&pdev->dev, sizeof(struct rockchip_spi));
>         if (!master)
>                 return -ENOMEM;
>
>         platform_set_drvdata(pdev, master);
>
>         rs = spi_master_get_devdata(master);
> +       rs->slave_mode = slave_mode;

This entry doesn't seem to be read from any of your code, and even it
it was, the same information is available in master->slave, so I don't
see why you need it in the rockchip_spi struct.

Also spi_master is just #defined to spi_controller in spi.h, so maybe
consider changing all 'struct spi_master *master' to 'struct
spi_controller *ctrl' now that the driver supports both modes.

>
>         /* Get basic io resource and map it */
>         mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> @@ -676,7 +704,16 @@ static int rockchip_spi_probe(struct platform_device *pdev)
>         master->auto_runtime_pm = true;
>         master->bus_num = pdev->id;
>         master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LOOP | SPI_LSB_FIRST;
> -       master->num_chipselect = ROCKCHIP_SPI_MAX_CS_NUM;
> +       if (slave_mode) {
> +               master->mode_bits |= SPI_NO_CS;
> +               master->slave_abort = rockchip_spi_slave_abort;
> +       } else {
> +               of_property_read_u32(np, "num-cs", &num_cs);
> +               master->num_chipselect = num_cs;

If you do something like this you won't need the temporary num_cs variable:

if (of_property_read_u32(np, "num-cs", &master->num_chipselect))
    master->num_chipselect = 1;

Also it seems like you're changing the default from
ROCKCHIP_SPI_MAX_CS_NUM to 1 if there is no num-cs property. Did you
check that all boards either have the num-cs property defined or only
needs num_chipselect = 1?

> +               master->use_gpio_descriptors = true;
> +               master->max_native_cs = ROCKCHIP_SPI_MAX_CS_NUM;
> +               master->flags = SPI_MASTER_GPIO_SS;
> +       }
>         master->dev.of_node = pdev->dev.of_node;
>         master->bits_per_word_mask = SPI_BPW_MASK(16) | SPI_BPW_MASK(8) | SPI_BPW_MASK(4);
>         master->min_speed_hz = rs->freq / BAUDR_SCKDV_MAX;
> @@ -686,7 +723,6 @@ static int rockchip_spi_probe(struct platform_device *pdev)
>         master->transfer_one = rockchip_spi_transfer_one;
>         master->max_transfer_size = rockchip_spi_max_transfer_size;
>         master->handle_err = rockchip_spi_handle_err;
> -       master->flags = SPI_MASTER_GPIO_SS;
>
>         master->dma_tx = dma_request_chan(rs->dev, "tx");
>         if (IS_ERR(master->dma_tx)) {
> --
> 2.20.1
>
>
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