linux-kernel - Re: [PATCH v13 05/15] mtd: spi-nor: sfdp: get command opcode extension type from BFPT

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Message-ID: <db90b212-cbf9-a675-024d-11a4969b9a6b@microchip.com>
Date:   Wed, 30 Sep 2020 06:17:01 +0000
From:   <Tudor.Ambarus@...rochip.com>
To:     <p.yadav@...com>, <miquel.raynal@...tlin.com>, <richard@....at>,
        <vigneshr@...com>, <linux-mtd@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
CC:     <nsekhar@...com>, <boris.brezillon@...labora.com>
Subject: Re: [PATCH v13 05/15] mtd: spi-nor: sfdp: get command opcode
 extension type from BFPT

On 9/16/20 3:44 PM, Pratyush Yadav wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> Some devices in DTR mode expect an extra command byte called the
> extension. The extension can either be same as the opcode, bitwise
> inverse of the opcode, or another additional byte forming a 16-byte
> opcode. Get the extension type from the BFPT. For now, only flashes with
> "repeat" and "inverse" extensions are supported.
> 
> Signed-off-by: Pratyush Yadav <p.yadav@...com>

Reviewed-by: Tudor Ambarus <tudor.ambarus@...rochip.com>

> ---
>  drivers/mtd/spi-nor/sfdp.c | 18 ++++++++++++++++++
>  drivers/mtd/spi-nor/sfdp.h |  6 ++++++
>  2 files changed, 24 insertions(+)
> 
> diff --git a/drivers/mtd/spi-nor/sfdp.c b/drivers/mtd/spi-nor/sfdp.c
> index 21fa9ab78eae..c77655968f80 100644
> --- a/drivers/mtd/spi-nor/sfdp.c
> +++ b/drivers/mtd/spi-nor/sfdp.c
> @@ -606,6 +606,24 @@ static int spi_nor_parse_bfpt(struct spi_nor *nor,
>         if (bfpt_header->length == BFPT_DWORD_MAX_JESD216B)
>                 return spi_nor_post_bfpt_fixups(nor, bfpt_header, &bfpt,
>                                                 params);
> +       /* 8D-8D-8D command extension. */
> +       switch (bfpt.dwords[BFPT_DWORD(18)] & BFPT_DWORD18_CMD_EXT_MASK) {
> +       case BFPT_DWORD18_CMD_EXT_REP:
> +               nor->cmd_ext_type = SPI_NOR_EXT_REPEAT;
> +               break;
> +
> +       case BFPT_DWORD18_CMD_EXT_INV:
> +               nor->cmd_ext_type = SPI_NOR_EXT_INVERT;
> +               break;
> +
> +       case BFPT_DWORD18_CMD_EXT_RES:
> +               dev_dbg(nor->dev, "Reserved command extension used\n");
> +               break;
> +
> +       case BFPT_DWORD18_CMD_EXT_16B:
> +               dev_dbg(nor->dev, "16-bit opcodes not supported\n");
> +               return -EOPNOTSUPP;
> +       }
> 
>         return spi_nor_post_bfpt_fixups(nor, bfpt_header, &bfpt, params);
>  }
> diff --git a/drivers/mtd/spi-nor/sfdp.h b/drivers/mtd/spi-nor/sfdp.h
> index 7f9846b3a1ad..6d7243067252 100644
> --- a/drivers/mtd/spi-nor/sfdp.h
> +++ b/drivers/mtd/spi-nor/sfdp.h
> @@ -90,6 +90,12 @@ struct sfdp_bfpt {
>  #define BFPT_DWORD15_QER_SR2_BIT1_NO_RD                (0x4UL << 20)
>  #define BFPT_DWORD15_QER_SR2_BIT1              (0x5UL << 20) /* Spansion */
> 
> +#define BFPT_DWORD18_CMD_EXT_MASK              GENMASK(30, 29)
> +#define BFPT_DWORD18_CMD_EXT_REP               (0x0UL << 29) /* Repeat */
> +#define BFPT_DWORD18_CMD_EXT_INV               (0x1UL << 29) /* Invert */
> +#define BFPT_DWORD18_CMD_EXT_RES               (0x2UL << 29) /* Reserved */
> +#define BFPT_DWORD18_CMD_EXT_16B               (0x3UL << 29) /* 16-bit opcode */
> +
>  struct sfdp_parameter_header {
>         u8              id_lsb;
>         u8              minor;
> --
> 2.28.0
>