[PATCH] mtd: cfi: Fix PPB lock status readout

[Stefan Roese]

On 11.04.21 20:47, Marek Vasut wrote:
> According to S26KL512S datasheet [1] and S29GL01GS datasheet [2],
> the procedure to read out PPB lock bits is to send the PPB Entry,
> PPB Read, Reset/ASO Exit. Currently, the code does send incorrect
> PPB Entry, PPB Read and Reset/ASO Exit is completely missing.
> 
> The PPB Entry sent is implemented by sending flash_unlock_seq()
> and flash_write_cmd(..., FLASH_CMD_READ_ID). This translates to
> sequence 0x555:0xaa, 0x2aa:0x55, 0x555:0x90=FLASH_CMD_READ_ID.
> However, both [1] and [2] specify the last byte of PPB Entry as
> 0xc0=AMD_CMD_SET_PPB_ENTRY instead of 0x90=FLASH_CMD_READ_ID,
> that is  0x555:0xaa, 0x2aa:0x55, 0x555:0xc0=AMD_CMD_SET_PPB_ENTRY.
> Since this does make sense, this patch fixes it and thus also
> aligns the code in flash_get_size() with flash_real_protect().
> 
> The PPB Read returns 00h in case of Protected state and 01h in case
> of Unprotected state, according to [1] Note 83 and [2] Note 17, so
> invert the result. Moreover, align the arguments with similar code
> in flash_real_protect().
> 
> Finally, Reset/ASO Exit command should be executed to exit the PPB
> mode, so add the missing reset.
> 
> [1] https://www.cypress.com/file/213346/download
>      Document Number: 001-99198 Rev. *M
>      Table 40. Command Definitions, Nonvolatile Sector Protection
>      Command Set Definitions
> [2] https://www.cypress.com/file/177976/download
>      Document Number: 001-98285 Rev. *R
>      Table 7.1 Command Definitions, Nonvolatile Sector Protection
>      Command Set Definitions
> 
> Fixes: 03deff433e ("cfi_flash: Read PPB sector protection from device for AMD/Spansion chips")
> Signed-off-by: Marek Vasut <marek.vasut+renesas at gmail.com>
> Cc: Stefan Roese <sr at denx.de>

Reviewed-by: Stefan Roese <sr at denx.de>

Thanks,
Stefan

> ---
>   drivers/mtd/cfi_flash.c | 10 +++++-----
>   1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/mtd/cfi_flash.c b/drivers/mtd/cfi_flash.c
> index 9642d7c7dc..9c27fea5d8 100644
> --- a/drivers/mtd/cfi_flash.c
> +++ b/drivers/mtd/cfi_flash.c
> @@ -2276,12 +2276,12 @@ ulong flash_get_size(phys_addr_t base, int banknum)
>   					flash_unlock_seq(info, 0);
>   					flash_write_cmd(info, 0,
>   							info->addr_unlock1,
> -							FLASH_CMD_READ_ID);
> +							AMD_CMD_SET_PPB_ENTRY);
>   					info->protect[sect_cnt] =
> -						flash_isset(
> -							info, sect_cnt,
> -							FLASH_OFFSET_PROTECT,
> -							FLASH_STATUS_PROTECT);
> +						!flash_isset(info, sect_cnt,
> +							     0, 0x01);
> +					flash_write_cmd(info, 0, 0,
> +							info->cmd_reset);
>   					break;
>   				default:
>   					/* default: not protected */
> 


Viele Grüße,
Stefan

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