linux-kernel - Re: [PATCH v14 10/15] mtd: spi-nor: Parse SFDP SCCR Map

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Message-ID: <81fa2331-d808-fed6-232f-f8b67e7e9dac@microchip.com>
Date:   Thu, 1 Oct 2020 08:20:54 +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 v14 10/15] mtd: spi-nor: Parse SFDP SCCR Map

On 9/30/20 9:57 PM, Pratyush Yadav wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> From: Tudor Ambarus <tudor.ambarus@...rochip.com>
> 
> Parse just the 22nd dword and look for the 'DTR Octal Mode Enable
> Volatile bit'.
> 
> SPI_NOR_IO_MODE_EN_VOLATILE should be set just for the flashes
> that don't define the optional SFDP SCCR Map. For the others,
> let the SFDP do its job and fill the SNOR_F_IO_MODE_EN_VOLATILE
> flag. We avoid this way polluting the flash flags when declaring
> one.
> 
> Signed-off-by: Tudor Ambarus <tudor.ambarus@...rochip.com>
> Signed-off-by: Pratyush Yadav <p.yadav@...com>
> ---
>  drivers/mtd/spi-nor/sfdp.c | 52 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 52 insertions(+)
> 
> diff --git a/drivers/mtd/spi-nor/sfdp.c b/drivers/mtd/spi-nor/sfdp.c
> index ebc1188f7533..0b5b9ea44cfc 100644
> --- a/drivers/mtd/spi-nor/sfdp.c
> +++ b/drivers/mtd/spi-nor/sfdp.c
> @@ -21,6 +21,10 @@
>  #define SFDP_SECTOR_MAP_ID     0xff81  /* Sector Map Table */
>  #define SFDP_4BAIT_ID          0xff84  /* 4-byte Address Instruction Table */
>  #define SFDP_PROFILE1_ID       0xff05  /* xSPI Profile 1.0 table. */
> +#define SFDP_SCCR_MAP_ID       0xff87  /*
> +                                        * Status, Control and Configuration
> +                                        * Register Map.
> +                                        */
> 
>  #define SFDP_SIGNATURE         0x50444653U
> 
> @@ -1195,6 +1199,50 @@ static int spi_nor_parse_profile1(struct spi_nor *nor,
>         return ret;
>  }
> 
> +#define SCCR_DWORD22_OCTAL_DTR_EN_VOLATILE             BIT(31)
> +
> +/**
> + * spi_nor_parse_sccr() - Parse the Status, Control and Configuration Register
> + *                        Map.
> + * @nor:               pointer to a 'struct spi_nor'
> + * @sccr_header:       pointer to the 'struct sfdp_parameter_header' describing
> + *                     the SCCR Map table length and version.
> + * @params:            pointer to the 'struct spi_nor_flash_parameter' to be.
> + *
> + * Return: 0 on success, -errno otherwise.
> + */
> +static int spi_nor_parse_sccr(struct spi_nor *nor,
> +                             const struct sfdp_parameter_header *sccr_header,
> +                             struct spi_nor_flash_parameter *params)
> +{
> +       u32 *dwords, addr;
> +       size_t len;
> +       int ret;
> +       u8 io_mode_en_volatile;

would a bool work here?

> +
> +       len = sccr_header->length * sizeof(*dwords);
> +       dwords = kmalloc(len, GFP_KERNEL);
> +       if (!dwords)
> +               return -ENOMEM;
> +
> +       addr = SFDP_PARAM_HEADER_PTP(sccr_header);
> +       ret = spi_nor_read_sfdp(nor, addr, len, dwords);
> +       if (ret)
> +               goto out;
> +
> +       le32_to_cpu_array(dwords, sccr_header->length);
> +
> +       io_mode_en_volatile = FIELD_GET(SCCR_DWORD22_OCTAL_DTR_EN_VOLATILE,
> +                                       dwords[22]);
> +
> +       if (io_mode_en_volatile)
> +               nor->flags |= SNOR_F_IO_MODE_EN_VOLATILE;
> +
> +out:
> +       kfree(dwords);
> +       return ret;
> +}
> +
>  /**
>   * spi_nor_parse_sfdp() - parse the Serial Flash Discoverable Parameters.
>   * @nor:               pointer to a 'struct spi_nor'
> @@ -1300,6 +1348,10 @@ int spi_nor_parse_sfdp(struct spi_nor *nor,
>                         err = spi_nor_parse_profile1(nor, param_header, params);
>                         break;
> 
> +               case SFDP_SCCR_MAP_ID:
> +                       err = spi_nor_parse_sccr(nor, param_header, params);
> +                       break;
> +
>                 default:
>                         break;
>                 }
> --
> 2.28.0
>