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Date:   Thu, 21 Jan 2021 12:19:51 +0100
From:   Michael Walle <michael@walle.cc>
To:     Tudor Ambarus <tudor.ambarus@microchip.com>
Cc:     vigneshr@ti.com, p.yadav@ti.com, miquel.raynal@bootlin.com,
        richard@nod.at, linux-mtd@lists.infradead.org,
        linux-kernel@vger.kernel.org, Kavyasree.Kotagiri@microchip.com
Subject: Re: [PATCH v3 2/2] mtd: spi-nor: sst: Add support for Global Unlock
 on sst26vf
In-Reply-To: <20210121110546.382633-2-tudor.ambarus@microchip.com>
References: <20210121110546.382633-1-tudor.ambarus@microchip.com>
 <20210121110546.382633-2-tudor.ambarus@microchip.com>
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Am 2021-01-21 12:05, schrieb Tudor Ambarus:
> Even if sst26vf shares the SPINOR_OP_GBULK opcode with
> Macronix (ex. MX25U12835F) and Winbound (ex. W25Q128FV),
> it has its own Individual Block Protection scheme, which
> is also capable to read-lock individual parameter blocks.
> Thus the sst26vf's Individual Block Protection scheme will
> reside in the sst.c manufacturer driver.
> 
> Add support to unlock the entire flash memory. The device
> is write-protected by default after a power-on reset cycle
> (volatile software protection), in order to avoid inadvertent
> writes during power-up. Could do an erase, write, read back,
> and compare when MTD_SPI_NOR_SWP_DISABLE_ON_VOLATILE=y.
> 
> Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>

Reviewed-by: Michael Walle <michael@walle.cc>

> ---
> v3:
> - s/Winbound/Winbond/
> - read CR.BPNV and check if we can really unlock the entire flash array
> - sst26vf_unlock: return -EINVAL instead of -EOPNOTSUPP when caller
> asks to unlock a range/granularity that we can't unlock
> 
> v2: v2: s/!ofs/ofs == 0/
> 
>  drivers/mtd/spi-nor/core.c |  2 +-
>  drivers/mtd/spi-nor/core.h |  1 +
>  drivers/mtd/spi-nor/sst.c  | 52 ++++++++++++++++++++++++++++++++++++--
>  3 files changed, 52 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index e82732dd31e1..c50b30fbb912 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -465,7 +465,7 @@ static int spi_nor_read_fsr(struct spi_nor *nor, u8 
> *fsr)
>   *
>   * Return: 0 on success, -errno otherwise.
>   */
> -static int spi_nor_read_cr(struct spi_nor *nor, u8 *cr)
> +int spi_nor_read_cr(struct spi_nor *nor, u8 *cr)
>  {
>  	int ret;
> 
> diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
> index eb26796db026..4a3f7f150b5d 100644
> --- a/drivers/mtd/spi-nor/core.h
> +++ b/drivers/mtd/spi-nor/core.h
> @@ -441,6 +441,7 @@ 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_read_sr(struct spi_nor *nor, u8 *sr);
> +int spi_nor_read_cr(struct spi_nor *nor, u8 *cr);
>  int spi_nor_write_sr(struct spi_nor *nor, const u8 *sr, size_t len);
>  int spi_nor_write_sr_and_check(struct spi_nor *nor, u8 sr1);
> 
> diff --git a/drivers/mtd/spi-nor/sst.c b/drivers/mtd/spi-nor/sst.c
> index 00e48da0744a..980f4c09c91d 100644
> --- a/drivers/mtd/spi-nor/sst.c
> +++ b/drivers/mtd/spi-nor/sst.c
> @@ -8,6 +8,53 @@
> 
>  #include "core.h"
> 
> +#define SST26VF_CR_BPNV		BIT(3)
> +
> +static int sst26vf_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +static int sst26vf_unlock(struct spi_nor *nor, loff_t ofs, uint64_t 
> len)
> +{
> +	int ret;
> +
> +	/* We only support unlocking the entire flash array. */
> +	if (ofs != 0 || len != nor->params->size)
> +		return -EINVAL;
> +
> +	ret = spi_nor_read_cr(nor, nor->bouncebuf);
> +	if (ret)
> +		return ret;
> +
> +	if (!(nor->bouncebuf[0] & SST26VF_CR_BPNV)) {
> +		dev_dbg(nor->dev, "Any block has been permanently locked\n");
> +		return -EINVAL;
> +	}
> +
> +	return spi_nor_global_block_unlock(nor);
> +}
> +
> +static int sst26vf_is_locked(struct spi_nor *nor, loff_t ofs, uint64_t 
> len)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +static const struct spi_nor_locking_ops sst26vf_locking_ops = {
> +	.lock = sst26vf_lock,
> +	.unlock = sst26vf_unlock,
> +	.is_locked = sst26vf_is_locked,
> +};
> +
> +static void sst26vf_default_init(struct spi_nor *nor)
> +{
> +	nor->params->locking_ops = &sst26vf_locking_ops;
> +}
> +
> +static const struct spi_nor_fixups sst26vf_fixups = {
> +	.default_init = sst26vf_default_init,
> +};
> +
>  static const struct flash_info sst_parts[] = {
>  	/* SST -- large erase sizes are "overlays", "sectors" are 4K */
>  	{ "sst25vf040b", INFO(0xbf258d, 0, 64 * 1024,  8,
> @@ -39,8 +86,9 @@ static const struct flash_info sst_parts[] = {
>  	{ "sst26vf016b", INFO(0xbf2641, 0, 64 * 1024, 32,
>  			      SECT_4K | SPI_NOR_DUAL_READ) },
>  	{ "sst26vf064b", INFO(0xbf2643, 0, 64 * 1024, 128,
> -			      SECT_4K | SPI_NOR_DUAL_READ |
> -			      SPI_NOR_QUAD_READ) },
> +			      SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ |
> +			      SPI_NOR_HAS_LOCK | SPI_NOR_SWP_IS_VOLATILE)
> +		.fixups = &sst26vf_fixups },
>  };
> 
>  static int sst_write(struct mtd_info *mtd, loff_t to, size_t len,