Re: [PATCH v3 2/5] mtd: spi-nor: cadence-quadspi: add a delay in write sequence

From: Marek Vasut
Date: Sun Sep 24 2017 - 08:12:03 EST


On 09/24/2017 12:59 PM, Vignesh R wrote:
> As per 66AK2G02 TRM[1] SPRUHY8F section 11.15.5.3 Indirect Access
> Controller programming sequence, a delay equal to couple of QSPI master
> clock(~5ns) is required after setting CQSPI_REG_INDIRECTWR_START bit and
> writing data to the flash. Introduce a quirk flag CQSPI_NEEDS_WR_DELAY
> to handle this and set this flag for TI 66AK2G SoC.
>
> [1]http://www.ti.com/lit/ug/spruhy8f/spruhy8f.pdf
>
> Signed-off-by: Vignesh R <vigneshr@xxxxxx>

Is this TI specific or is this controller property ? I wouldn't be
surprised of the later ...

> ---
>
> v3:
> Fix build warnings reported by kbuild test bot.
>
> drivers/mtd/spi-nor/cadence-quadspi.c | 27 ++++++++++++++++++++++++++-
> 1 file changed, 26 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mtd/spi-nor/cadence-quadspi.c b/drivers/mtd/spi-nor/cadence-quadspi.c
> index 53c7d8e0327a..5cd5d6f7303f 100644
> --- a/drivers/mtd/spi-nor/cadence-quadspi.c
> +++ b/drivers/mtd/spi-nor/cadence-quadspi.c
> @@ -38,6 +38,9 @@
> #define CQSPI_NAME "cadence-qspi"
> #define CQSPI_MAX_CHIPSELECT 16
>
> +/* Quirks */
> +#define CQSPI_NEEDS_WR_DELAY BIT(0)
> +
> struct cqspi_st;
>
> struct cqspi_flash_pdata {
> @@ -76,6 +79,7 @@ struct cqspi_st {
> u32 fifo_depth;
> u32 fifo_width;
> u32 trigger_address;
> + u32 wr_delay;
> struct cqspi_flash_pdata f_pdata[CQSPI_MAX_CHIPSELECT];
> };
>
> @@ -608,6 +612,15 @@ static int cqspi_indirect_write_execute(struct spi_nor *nor,
> reinit_completion(&cqspi->transfer_complete);
> writel(CQSPI_REG_INDIRECTWR_START_MASK,
> reg_base + CQSPI_REG_INDIRECTWR);
> + /*
> + * As per 66AK2G02 TRM SPRUHY8F section 11.15.5.3 Indirect Access
> + * Controller programming sequence, couple of cycles of
> + * QSPI_REF_CLK delay is required for the above bit to
> + * be internally synchronized by the QSPI module. Provide 5
> + * cycles of delay.
> + */
> + if (cqspi->wr_delay)
> + ndelay(cqspi->wr_delay);
>
> while (remaining > 0) {
> write_bytes = remaining > page_size ? page_size : remaining;
> @@ -1156,6 +1169,7 @@ static int cqspi_probe(struct platform_device *pdev)
> struct cqspi_st *cqspi;
> struct resource *res;
> struct resource *res_ahb;
> + unsigned long data;
> int ret;
> int irq;
>
> @@ -1213,6 +1227,10 @@ static int cqspi_probe(struct platform_device *pdev)
> }
>
> cqspi->master_ref_clk_hz = clk_get_rate(cqspi->clk);
> + data = (unsigned long)of_device_get_match_data(dev);
> + if (data & CQSPI_NEEDS_WR_DELAY)
> + cqspi->wr_delay = 5 * DIV_ROUND_UP(NSEC_PER_SEC,
> + cqspi->master_ref_clk_hz);
>
> ret = devm_request_irq(dev, irq, cqspi_irq_handler, 0,
> pdev->name, cqspi);
> @@ -1284,7 +1302,14 @@ static const struct dev_pm_ops cqspi__dev_pm_ops = {
> #endif
>
> static const struct of_device_id cqspi_dt_ids[] = {
> - {.compatible = "cdns,qspi-nor",},
> + {
> + .compatible = "cdns,qspi-nor",
> + .data = (void *)0,
> + },
> + {
> + .compatible = "ti,k2g-qspi",
> + .data = (void *)CQSPI_NEEDS_WR_DELAY,
> + },
> { /* end of table */ }
> };
>
>


--
Best regards,
Marek Vasut