linux-kernel - Re: [PATCH v7 6/7] mtd: spi-nor: atmel: fix unlock

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Message-ID: <9338f65d-ff5e-ade8-8beb-986445996da0@microchip.com>
Date:   Thu, 3 Dec 2020 14:44:54 +0000
From:   <Tudor.Ambarus@...rochip.com>
To:     <michael@...le.cc>, <linux-mtd@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
CC:     <miquel.raynal@...tlin.com>, <richard@....at>, <vigneshr@...com>,
        <boris.brezillon@...labora.com>
Subject: Re: [PATCH v7 6/7] mtd: spi-nor: atmel: fix unlock_all() for
 AT25FS010/040

On 12/3/20 1:00 AM, Michael Walle wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> These flashes have some weird BP bits mapping which aren't supported in
> the current locking code. Just add a simple unlock op to unprotect the
> entire flash array which is needed for legacy behavior.
> 
> Signed-off-by: Michael Walle <michael@...le.cc>

With fixes tag added, one can add:
Reviewed-by: Tudor Ambarus <tudor.ambarus@...rochip.com>

> ---
> changes since v6:
>  - use spi_nor_write_sr_and_check() and log a debug message if writing
>    fails
> 
> changes since v5:
>  - new patch
> 
>  drivers/mtd/spi-nor/atmel.c | 53 +++++++++++++++++++++++++++++++++++--
>  drivers/mtd/spi-nor/core.c  |  2 +-
>  drivers/mtd/spi-nor/core.h  |  1 +
>  3 files changed, 53 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/atmel.c b/drivers/mtd/spi-nor/atmel.c
> index 49d392c6c8bc..ee382a44bd0f 100644
> --- a/drivers/mtd/spi-nor/atmel.c
> +++ b/drivers/mtd/spi-nor/atmel.c
> @@ -8,10 +8,59 @@
> 
>  #include "core.h"
> 
> +/*
> + * The Atmel AT25FS010/AT25FS040 parts have some weird configuration for the
> + * block protection bits. We don't support them. But legacy behavior in linux
> + * is to unlock the whole flash array on startup. Therefore, we have to support
> + * exactly this operation.
> + */
> +static int atmel_at25fs_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
> +{
> +       return -EOPNOTSUPP;
> +}
> +
> +static int atmel_at25fs_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
> +{
> +       int ret;
> +
> +       /* We only support unlocking the whole flash array */
> +       if (ofs || len != nor->params->size)
> +               return -EINVAL;
> +
> +       /* Write 0x00 to the status register to disable write protection */
> +       ret = spi_nor_write_sr_and_check(nor, 0);
> +       if (ret)
> +               dev_dbg(nor->dev, "unable to clear BP bits, WP# asserted?\n");
> +
> +       return ret;
> +}
> +
> +static int atmel_at25fs_is_locked(struct spi_nor *nor, loff_t ofs, uint64_t len)
> +{
> +       return -EOPNOTSUPP;
> +}
> +
> +static const struct spi_nor_locking_ops atmel_at25fs_locking_ops = {
> +       .lock = atmel_at25fs_lock,
> +       .unlock = atmel_at25fs_unlock,
> +       .is_locked = atmel_at25fs_is_locked,
> +};
> +
> +static void atmel_at25fs_default_init(struct spi_nor *nor)
> +{
> +       nor->params->locking_ops = &atmel_at25fs_locking_ops;
> +}
> +
> +static const struct spi_nor_fixups atmel_at25fs_fixups = {
> +       .default_init = atmel_at25fs_default_init,
> +};
> +
>  static const struct flash_info atmel_parts[] = {
>         /* Atmel -- some are (confusingly) marketed as "DataFlash" */
> -       { "at25fs010",  INFO(0x1f6601, 0, 32 * 1024,   4, SECT_4K | SPI_NOR_HAS_LOCK) },
> -       { "at25fs040",  INFO(0x1f6604, 0, 64 * 1024,   8, SECT_4K | SPI_NOR_HAS_LOCK) },
> +       { "at25fs010",  INFO(0x1f6601, 0, 32 * 1024,   4, SECT_4K | SPI_NOR_HAS_LOCK)
> +               .fixups = &atmel_at25fs_fixups },
> +       { "at25fs040",  INFO(0x1f6604, 0, 64 * 1024,   8, SECT_4K | SPI_NOR_HAS_LOCK)
> +               .fixups = &atmel_at25fs_fixups },
> 
>         { "at25df041a", INFO(0x1f4401, 0, 64 * 1024,   8, SECT_4K | SPI_NOR_HAS_LOCK) },
>         { "at25df321",  INFO(0x1f4700, 0, 64 * 1024,  64, SECT_4K | SPI_NOR_HAS_LOCK) },
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index 013198abe929..6afcb99e9741 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -1049,7 +1049,7 @@ static int spi_nor_write_16bit_cr_and_check(struct spi_nor *nor, u8 cr)
>   *
>   * Return: 0 on success, -errno otherwise.
>   */
> -static int spi_nor_write_sr_and_check(struct spi_nor *nor, u8 sr1)
> +int spi_nor_write_sr_and_check(struct spi_nor *nor, u8 sr1)
>  {
>         if (nor->flags & SNOR_F_HAS_16BIT_SR)
>                 return spi_nor_write_16bit_sr_and_check(nor, sr1);
> diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
> index 0a775a7b5606..7780169d485b 100644
> --- a/drivers/mtd/spi-nor/core.h
> +++ b/drivers/mtd/spi-nor/core.h
> @@ -430,6 +430,7 @@ void spi_nor_unlock_and_unprep(struct spi_nor *nor);
>  int spi_nor_sr1_bit6_quad_enable(struct spi_nor *nor);
>  int spi_nor_sr2_bit1_quad_enable(struct spi_nor *nor);
>  int spi_nor_sr2_bit7_quad_enable(struct spi_nor *nor);
> +int spi_nor_write_sr_and_check(struct spi_nor *nor, u8 sr1);
> 
>  int spi_nor_xread_sr(struct spi_nor *nor, u8 *sr);
>  ssize_t spi_nor_read_data(struct spi_nor *nor, loff_t from, size_t len,
> --
> 2.20.1
>