Re: [PATCH 1/1 v3] driver:mtd:spi-nor: Add quad I/O support for Micron spi nor

Jagan Teki
2014-11-12T20:59:31Z

On 27 October 2014 05:39, bpqw <bpqw@micron.com> wrote:
> This patch adds code which enables Quad I/O mode on Micron SPI NOR flashes.
>
> For Micron SPI NOR flash, enabling or disabling quad I/O protocol is controlled
> by EVCR (Enhanced Volatile Configuration Register), Quad I/O protocol bit 7.
> When EVCR bit 7 is reset to 0, the SPI NOR flash will operate in quad I/O mode.
>
> Signed-off-by: bean huo <beanhuo@micron.com>
> Acked-by: Marek Vasut <marex@denx.de>
> ---
> v1-v2:modified to that capture wait_till_ready()
> return value,if error,directly return its
> the value.
> v2-v3:directly use the reurning error value of
> read_reg and write_reg,instead of -EINVAL.
>
> drivers/mtd/spi-nor/spi-nor.c | 46 +++++++++++++++++++++++++++++++++++++++++
> include/linux/mtd/spi-nor.h | 6 ++++++
> 2 files changed, 52 insertions(+)
>
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c index b5ad6be..486b167 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -878,6 +878,45 @@ static int spansion_quad_enable(struct spi_nor *nor)
> return 0;
> }
>
> +static int micron_quad_enable(struct spi_nor *nor) {
> + int ret, val;
> +
> + ret = nor->read_reg(nor, SPINOR_OP_RD_EVCR, &val, 1);
> + if (ret < 0) {
> + dev_err(nor->dev, "error %d reading EVCR\n", ret);
> + return ret;
> + }

Best to define read_evsr()

> +
> + write_enable(nor);
> +
> + /* set EVCR ,enable quad I/O */
> + nor->cmd_buf[0] = val & ~EVCR_QUAD_EN_MICRON;
> + ret = nor->write_reg(nor, SPINOR_OP_WD_EVCR, nor->cmd_buf, 1, 0);
> + if (ret < 0) {
> + dev_err(nor->dev,
> + "error while writing EVCR register\n");
> + return ret;
> + }
> +
> + ret = wait_till_ready(nor);
> + if (ret)
> + return ret;

I don't think this will ready w/o wait time or something - may be use
if (wait_till_ready(nor))
return 1;

> +
> + /* read EVCR and check it */
> + ret = nor->read_reg(nor, SPINOR_OP_RD_EVCR, &val, 1);
> + if (ret < 0) {
> + dev_err(nor->dev, "error %d reading EVCR\n", ret);
> + return ret;
> + }
> + if (val & EVCR_QUAD_EN_MICRON) {
> + dev_err(nor->dev, "Micron EVCR Quad bit not clear\n");
> + return -EINVAL;
> + }

IMHO, use read_evcr() as defined above and write the finite statement code like
ret = read_evcr(nor);
if (!(ret > 0 && (ret & EVCR_QUAD_EN_MICRON))) {
dev_err(nor->dev, "Micron EVCR Quad bit not clear\n");
return -EINVAL;
}

> +
> + return 0;
> +}
> +
> static int set_quad_mode(struct spi_nor *nor, u32 jedec_id) {
> int status;
> @@ -890,6 +929,13 @@ static int set_quad_mode(struct spi_nor *nor, u32 jedec_id)
> return -EINVAL;
> }
> return status;
> + case CFI_MFR_ST:
> + status = micron_quad_enable(nor);
> + if (status) {
> + dev_err(nor->dev, "Micron quad-read not enabled\n");
> + return -EINVAL;
> + }
> + return status;
> default:
> status = spansion_quad_enable(nor);
> if (status) {
> diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h index 9e6294f..d71b659 100644
> --- a/include/linux/mtd/spi-nor.h
> +++ b/include/linux/mtd/spi-nor.h
> @@ -56,6 +56,10 @@
> /* Used for Spansion flashes only. */
> #define SPINOR_OP_BRWR 0x17 /* Bank register write */
>
> +/* Used for Micron flashes only. */
> +#define SPINOR_OP_RD_EVCR 0x65 /* Read EVCR register */
> +#define SPINOR_OP_WD_EVCR 0x61 /* Write EVCR register */
> +
> /* Status Register bits. */
> #define SR_WIP 1 /* Write in progress */
> #define SR_WEL 2 /* Write enable latch */
> @@ -67,6 +71,8 @@
>
> #define SR_QUAD_EN_MX 0x40 /* Macronix Quad I/O */
>
> +#define EVCR_QUAD_EN_MICRON 0x80 /* Micron Quad I/O */
> +
> /* Flag Status Register bits */
> #define FSR_READY 0x80
>

thanks!
--
Jagan.