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SubjectRe: [PATCH 03/11] spi: dw: define spi_frf for dual/quad/octal modes
On Tue, Aug 02, 2022 at 06:57:47PM +0100, Sudip Mukherjee wrote:
> The SPI mode needs to be mentioned in CTRLR0[23:22] register. Define a
> configuration variable to keep the mode based on the buswidth, which will
> then be used to update CR0. If the transfer is using dual/quad/octal
> mode then mark enhanced_spi as true.
>
> Signed-off-by: Sudip Mukherjee <sudip.mukherjee@sifive.com>
> ---
> drivers/spi/spi-dw-core.c | 29 +++++++++++++++++++++++++++++
> drivers/spi/spi-dw.h | 7 +++++++
> 2 files changed, 36 insertions(+)
>
> diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c
> index 77529e359b6d..8c84a2e991b5 100644
> --- a/drivers/spi/spi-dw-core.c
> +++ b/drivers/spi/spi-dw-core.c
> @@ -333,6 +333,14 @@ void dw_spi_update_config(struct dw_spi *dws, struct spi_device *spi,
> /* CTRLR0[11:10] Transfer Mode */
> cr0 |= FIELD_PREP(DW_HSSI_CTRLR0_TMOD_MASK, cfg->tmode);
>

> + if (dws->caps & DW_SPI_CAP_EXT_SPI) {

Drop this conditional statement. Just always set the spi_frf field.


> + if (cfg->spi_frf)

Drop this conditional statement. Just always set the spi_frf. It shall
be zero if the Enhanced SPI modes are unsupported.

> + cr0 |= FIELD_PREP(DW_HSSI_CTRLR0_SPI_FRF_MASK,

Since the SPI_FRF field has different offset in the DW APB and DW AHB
SSI controllers, you'll need to initialize the mode based on the
IP-core ID using the dw_spi_ip_is() macro (see the as it's done for
tmode).

> + cfg->spi_frf);
> + else

> + cr0 &= ~DW_HSSI_CTRLR0_SPI_FRF_MASK;

This is redundant. The initial value never has the SPI_FRF field set
(see the dw_spi_setup() and dw_spi_prepare_cr0() methods for details).

> + }
> +
> dw_writel(dws, DW_SPI_CTRLR0, cr0);
>
> if (cfg->tmode == DW_SPI_CTRLR0_TMOD_EPROMREAD ||
> @@ -679,10 +687,31 @@ static void dw_spi_stop_mem_op(struct dw_spi *dws, struct spi_device *spi)
> static int dw_spi_exec_mem_op(struct spi_mem *mem, const struct spi_mem_op *op)
> {
> struct dw_spi *dws = spi_controller_get_devdata(mem->spi->controller);
> + bool enhanced_spi = false;
> struct dw_spi_cfg cfg;
> unsigned long flags;
> int ret;
>

> + if (dws->caps & DW_SPI_CAP_EXT_SPI) {
> + switch (op->data.buswidth) {
> + case 2:
> + cfg.spi_frf = DW_SSI_CTRLR0_SPI_FRF_DUAL_SPI;
> + enhanced_spi = true;
> + break;
> + case 4:
> + cfg.spi_frf = DW_SSI_CTRLR0_SPI_FRF_QUAD_SPI;
> + enhanced_spi = true;
> + break;
> + case 8:
> + cfg.spi_frf = DW_SSI_CTRLR0_SPI_FRF_OCT_SPI;
> + enhanced_spi = true;
> + break;
> + default:
> + cfg.spi_frf = 0;
> + break;
> + }
> + }
> +

Please create a separate dw_spi_exec_enh_mem_op() method for the
Enhanced SPI communications and parse the data.buswidth field there.
Also it would be better to define a new macro
DW_SSI_CTRLR0_SPI_FRF_STD_SPI and use it instead of the explicit zero
SPI_FRF value.

> /*
> * Collect the outbound data into a single buffer to speed the
> * transmission up at least on the initial stage.
> diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
> index 71d18e9291a3..b8cc20e0deaa 100644
> --- a/drivers/spi/spi-dw.h
> +++ b/drivers/spi/spi-dw.h
> @@ -96,6 +96,12 @@
> #define DW_HSSI_CTRLR0_SRL BIT(13)
> #define DW_HSSI_CTRLR0_MST BIT(31)
>

> +/* Bit fields in CTRLR0 for enhanced SPI */

No need in the comment. The macros name is descriptive enough.

> +#define DW_HSSI_CTRLR0_SPI_FRF_MASK GENMASK(23, 22)

Please also add the next new macros
#define DW_PSSI_CTRLR0_SPI_FRF_MASK GENMASK(22, 21)
#define DW_SSI_CTRLR0_SPI_FRF_STD_SPI 0x0

and group them together with the rest of the APB SSI CTRL0 macros.

> +#define DW_SSI_CTRLR0_SPI_FRF_DUAL_SPI 0x1
> +#define DW_SSI_CTRLR0_SPI_FRF_QUAD_SPI 0x2
> +#define DW_SSI_CTRLR0_SPI_FRF_OCT_SPI 0x3

Please move these to be defined together with the APB SSI
CTRL0.SPI_FRF-related macros.

-Sergey

> +
> /* Bit fields in CTRLR1 */
> #define DW_SPI_NDF_MASK GENMASK(15, 0)
>
> @@ -136,6 +142,7 @@ struct dw_spi_cfg {
> u8 dfs;
> u32 ndf;
> u32 freq;
> + u8 spi_frf;
> };
>
> struct dw_spi;
> --
> 2.30.2
>

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