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

[Chris Ruehl <chris.ruehl@gtsys.com.hk>]

Hi Emil,

thanks for the review and your comments

On 8/5/2020 9:13 pm, Emil Renner Berthing wrote:
> Hi Chris,
>
> On Fri, 8 May 2020 at 10:47, Chris Ruehl <chris.ruehl@gtsys.com.hk> 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@gtsys.com.hk>
>> ---
>>   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.
I haven't see the slave flag in the spi_controller struct, I will store the 
information
there.
>
> 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.
Can do,  but I think that is better to have a separate patch for it,
make it easier for review.
>
>>          /* 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;
Like it , can see clearly the fallback to a default if num-cs isn't set in the
dts.
>
> 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?
Only spi0 of the rockchip has a 2nd native chip select, all others a single only
therefore I find it less evil to use 1 vs. ROCKCHIP_SPI_MAX_CS_NUM

>> +               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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