Re: [V5 PATCH 1/1] driver:mtd:spi-nor: Add quad I/O support for Micron spi nor

Brian Norris
2014-11-26T21:12:46Z

First of all, can you fix your mail so that you have a proper 'From'?
That should be your real name (not bpqw), so that it gives a proper
patch author. If you can't get your mail header to have the right
'From:' line, then it also works to begin your mail with:

From: Your Name <your@email.com>

On Thu, Nov 06, 2014 at 03:09:06AM +0000, bpqw 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.

What's the difference between using EVCR and the ENTER QUAD I/O MODE
(35h) command I see in some of your datasheets? Are both supported on
all Micron quad I/O SPI NOR flash?

Also, which SPI NOR is this enabled for? I don't see any Micron entries
in spi_nor_ids[] which contain the SPI_NOR_QUAD_READ flag.

> 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.
> v3-v4:
> Modify commit logs that wraped into 80 columns
> v4-v5:
> Rebuild new patch based on latest linux-mtd

Please rebase on l2-mtd.git. Sorry if that wasn't clear earlier.

> 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 c51ee52..2a31742 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -874,6 +874,45 @@ 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;
> + }
> +
> + 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");

Join the above two lines?

> + return ret;
> + }
> +
> + ret = wait_till_ready(nor);

It's spi_nor_wait_till_ready(), now.

> + if (ret)
> + return ret;
> +
> + /* 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;
> + }
> +
> + return 0;
> +}
> +
> static int set_quad_mode(struct spi_nor *nor, u32 jedec_id)
> {
> int status;
> @@ -886,6 +925,13 @@ 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 046a0a2..42e7e37 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 */

Like with other register bitfields (SR, FSR), please place a comment
above to describe the register, like:

/* Enhanced Volatile Configuration Register bits */

> +
> /* Flag Status Register bits */
> #define FSR_READY 0x80
>

Brian