On Sat, Aug 20, 2022 at 12:57:45PM -0700, Brad Larson wrote:
> From: Brad Larson <blarson@xxxxxxx>
>
> The AMD Pensando Elba SoC includes a DW apb_ssi v4 controller
> with device specific chip-select control. The Elba SoC
> provides four chip-selects where the native DW IP supports
> two chip-selects. The Elba DW_SPI instance has two native
> CS signals that are always overridden.
>
> Signed-off-by: Brad Larson <blarson@xxxxxxx>
> ---
> drivers/spi/spi-dw-mmio.c | 77 +++++++++++++++++++++++++++++++++++++++
> 1 file changed, 77 insertions(+)
>
> diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
> index 26c40ea6dd12..36b8c5e10bb3 100644
> --- a/drivers/spi/spi-dw-mmio.c
> +++ b/drivers/spi/spi-dw-mmio.c
> @@ -53,6 +53,24 @@ struct dw_spi_mscc {
> void __iomem *spi_mst; /* Not sparx5 */
> };
>
> +struct dw_spi_elba {
> + struct regmap *syscon;
> +};
> +
> +/*
> + * Elba SoC does not use ssi, pin override is used for cs 0,1 and
> + * gpios for cs 2,3 as defined in the device tree.
> + *
> + * cs: | 1 0
> + * bit: |---3-------2-------1-------0
> + * | cs1 cs1_ovr cs0 cs0_ovr
> + */
> +#define ELBA_SPICS_REG 0x2468
> +#define ELBA_SPICS_SHIFT(cs) (2 * (cs))
> +#define ELBA_SPICS_MASK(cs) (0x3 << ELBA_SPICS_SHIFT(cs))
> +#define ELBA_SPICS_SET(cs, val) \
> + ((((val) << 1) | 0x1) << ELBA_SPICS_SHIFT(cs))
Please take the @Andy' notes into account:
https://lore.kernel.org/lkml/CAHp75Vex0VkECYd=kY0m6=jXBYSXg2UFu7vn271+Q49WZn22GA@xxxxxxxxxxxxxx/
One more nitpick below.
> +
> /*
> * The Designware SPI controller (referred to as master in the documentation)
> * automatically deasserts chip select when the tx fifo is empty. The chip
> @@ -237,6 +255,64 @@ static int dw_spi_canaan_k210_init(struct platform_device *pdev,
> return 0;
> }
>
> +static void dw_spi_elba_override_cs(struct dw_spi_elba *dwselba, int cs, int enable)
> +{
> + regmap_update_bits(dwselba->syscon, ELBA_SPICS_REG, ELBA_SPICS_MASK(cs),
> + ELBA_SPICS_SET(cs, enable));
> +}
> +
> +static void dw_spi_elba_set_cs(struct spi_device *spi, bool enable)
> +{
> + struct dw_spi *dws = spi_master_get_devdata(spi->master);
> + struct dw_spi_mmio *dwsmmio = container_of(dws, struct dw_spi_mmio, dws);
> + struct dw_spi_elba *dwselba = dwsmmio->priv;
> + u8 cs;
> +
> + cs = spi->chip_select;
> + if (cs < 2)
> + dw_spi_elba_override_cs(dwselba, spi->chip_select, enable);
> +
> + /*
> + * The DW SPI controller needs a native CS bit selected to start
> + * the serial engine.
> + */
> + spi->chip_select = 0;
> + dw_spi_set_cs(spi, enable);
> + spi->chip_select = cs;
> +}
> +
> +static int dw_spi_elba_init(struct platform_device *pdev,
> + struct dw_spi_mmio *dwsmmio)
> +{
> + const char *syscon_name = "amd,pensando-elba-syscon";
> + struct device_node *np = pdev->dev.of_node;
> + struct device_node *node;
> + struct dw_spi_elba *dwselba;
Please, use the reverse xmas tree order of the local variables
as the rest of the driver mainly implies.
-Sergey
> + struct regmap *regmap;
> +
> + node = of_parse_phandle(np, syscon_name, 0);
> + if (!node) {
> + dev_err(&pdev->dev, "failed to find %s\n", syscon_name);
> + return -ENODEV;
> + }
> +
> + regmap = syscon_node_to_regmap(node);
> + if (IS_ERR(regmap)) {
> + dev_err(&pdev->dev, "syscon regmap lookup failed\n");
> + return PTR_ERR(regmap);
> + }
> +
> + dwselba = devm_kzalloc(&pdev->dev, sizeof(*dwselba), GFP_KERNEL);
> + if (!dwselba)
> + return -ENOMEM;
> +
> + dwselba->syscon = regmap;
> + dwsmmio->priv = dwselba;
> + dwsmmio->dws.set_cs = dw_spi_elba_set_cs;
> +
> + return 0;
> +}
> +
> static int dw_spi_mmio_probe(struct platform_device *pdev)
> {
> int (*init_func)(struct platform_device *pdev,
> @@ -352,6 +428,7 @@ static const struct of_device_id dw_spi_mmio_of_match[] = {
> { .compatible = "intel,thunderbay-ssi", .data = dw_spi_intel_init},
> { .compatible = "microchip,sparx5-spi", dw_spi_mscc_sparx5_init},
> { .compatible = "canaan,k210-spi", dw_spi_canaan_k210_init},
> + { .compatible = "amd,pensando-elba-spi", .data = dw_spi_elba_init},
> { /* end of table */}
> };
> MODULE_DEVICE_TABLE(of, dw_spi_mmio_of_match);
> --
> 2.17.1
>
