[U-Boot] [PATCH v4 15/16] spi: sf_ops: Add SPI protection mechanism from the kernel

Jagan Teki jteki at openedev.com
Fri Oct 30 17:29:50 CET 2015


On 26 October 2015 at 21:41, Fabio Estevam <fabio.estevam at freescale.com> wrote:
> Add the SPI NOR protection mechanism from the kernel.
>
> This code is based on the work from Brian Norris <computersforpeace at gmail.com>
>
> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/drivers/mtd/spi-nor/spi-nor.c?id=62593cf40b23b523b9fc9334ca61ba6c595ebb09
>
> Signed-off-by: Fabio Estevam <fabio.estevam at freescale.com>
> Reviewed-by: Tom Rini <trini at konsulko.com>
> Reviewed-by: Heiko Schocher <hs at denx.de>
> ---

Reviewed-by: Jagan Teki <jteki at openedev.com>

> Changes since v3:
> - None
>
>  drivers/mtd/spi/sf_ops.c | 170 +++++++++++++++++++++++++++++++++++++++++++++++
>  include/spi_flash.h      |   4 ++
>  2 files changed, 174 insertions(+)
>
> diff --git a/drivers/mtd/spi/sf_ops.c b/drivers/mtd/spi/sf_ops.c
> index 900ec1f..928f9c1 100644
> --- a/drivers/mtd/spi/sf_ops.c
> +++ b/drivers/mtd/spi/sf_ops.c
> @@ -15,6 +15,7 @@
>  #include <spi_flash.h>
>  #include <watchdog.h>
>  #include <linux/compiler.h>
> +#include <linux/log2.h>
>
>  #include "sf_internal.h"
>
> @@ -573,3 +574,172 @@ int sst_write_bp(struct spi_flash *flash, u32 offset, size_t len,
>         return ret;
>  }
>  #endif
> +
> +#ifdef CONFIG_SPI_FLASH_STMICRO
> +static void stm_get_locked_range(struct spi_flash *flash, u8 sr, loff_t *ofs,
> +                                u32 *len)
> +{
> +       u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
> +       int shift = ffs(mask) - 1;
> +       int pow;
> +
> +       if (!(sr & mask)) {
> +               /* No protection */
> +               *ofs = 0;
> +               *len = 0;
> +       } else {
> +               pow = ((sr & mask) ^ mask) >> shift;
> +               *len = flash->size >> pow;
> +               *ofs = flash->size - *len;
> +       }
> +}
> +
> +/*
> + * Return 1 if the entire region is locked, 0 otherwise
> + */
> +static int stm_is_locked_sr(struct spi_flash *flash, loff_t ofs, u32 len,
> +                           u8 sr)
> +{
> +       loff_t lock_offs;
> +       u32 lock_len;
> +
> +       stm_get_locked_range(flash, sr, &lock_offs, &lock_len);
> +
> +       return (ofs + len <= lock_offs + lock_len) && (ofs >= lock_offs);
> +}
> +
> +/*
> + * Check if a region of the flash is (completely) locked. See stm_lock() for
> + * more info.
> + *
> + * Returns 1 if entire region is locked, 0 if any portion is unlocked, and
> + * negative on errors.
> + */
> +int stm_is_locked(struct spi_flash *flash, loff_t ofs, u32 len)
> +{
> +       int status;
> +       u8 sr;
> +
> +       status = spi_flash_cmd_read_status(flash, &sr);
> +       if (status < 0)
> +               return status;
> +
> +       return stm_is_locked_sr(flash, ofs, len, sr);
> +}
> +
> +/*
> + * Lock a region of the flash. Compatible with ST Micro and similar flash.
> + * Supports only the block protection bits BP{0,1,2} in the status register
> + * (SR). Does not support these features found in newer SR bitfields:
> + *   - TB: top/bottom protect - only handle TB=0 (top protect)
> + *   - SEC: sector/block protect - only handle SEC=0 (block protect)
> + *   - CMP: complement protect - only support CMP=0 (range is not complemented)
> + *
> + * Sample table portion for 8MB flash (Winbond w25q64fw):
> + *
> + *   SEC  |  TB   |  BP2  |  BP1  |  BP0  |  Prot Length  | Protected Portion
> + *  --------------------------------------------------------------------------
> + *    X   |   X   |   0   |   0   |   0   |  NONE         | NONE
> + *    0   |   0   |   0   |   0   |   1   |  128 KB       | Upper 1/64
> + *    0   |   0   |   0   |   1   |   0   |  256 KB       | Upper 1/32
> + *    0   |   0   |   0   |   1   |   1   |  512 KB       | Upper 1/16
> + *    0   |   0   |   1   |   0   |   0   |  1 MB         | Upper 1/8
> + *    0   |   0   |   1   |   0   |   1   |  2 MB         | Upper 1/4
> + *    0   |   0   |   1   |   1   |   0   |  4 MB         | Upper 1/2
> + *    X   |   X   |   1   |   1   |   1   |  8 MB         | ALL
> + *
> + * Returns negative on errors, 0 on success.
> + */
> +int stm_lock(struct spi_flash *flash, u32 ofs, u32 len)
> +{
> +       u8 status_old, status_new;
> +       u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
> +       u8 shift = ffs(mask) - 1, pow, val;
> +
> +       spi_flash_cmd_read_status(flash, &status_old);
> +
> +       /* SPI NOR always locks to the end */
> +       if (ofs + len != flash->size) {
> +               /* Does combined region extend to end? */
> +               if (!stm_is_locked_sr(flash, ofs + len, flash->size - ofs - len,
> +                                     status_old))
> +                       return -EINVAL;
> +               len = flash->size - ofs;
> +       }
> +
> +       /*
> +        * Need smallest pow such that:
> +        *
> +        *   1 / (2^pow) <= (len / size)
> +        *
> +        * so (assuming power-of-2 size) we do:
> +        *
> +        *   pow = ceil(log2(size / len)) = log2(size) - floor(log2(len))
> +        */
> +       pow = ilog2(flash->size) - ilog2(len);
> +       val = mask - (pow << shift);
> +       if (val & ~mask)
> +               return -EINVAL;
> +
> +       /* Don't "lock" with no region! */
> +       if (!(val & mask))
> +               return -EINVAL;
> +
> +       status_new = (status_old & ~mask) | val;
> +
> +       /* Only modify protection if it will not unlock other areas */
> +       if ((status_new & mask) <= (status_old & mask))
> +               return -EINVAL;
> +
> +       spi_flash_cmd_write_status(flash, status_new);
> +
> +       return 0;
> +}
> +
> +/*
> + * Unlock a region of the flash. See stm_lock() for more info
> + *
> + * Returns negative on errors, 0 on success.
> + */
> +int stm_unlock(struct spi_flash *flash, u32 ofs, u32 len)
> +{
> +       uint8_t status_old, status_new;
> +       u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
> +       u8 shift = ffs(mask) - 1, pow, val;
> +
> +       spi_flash_cmd_read_status(flash, &status_old);
> +
> +       /* Cannot unlock; would unlock larger region than requested */
> +       if (stm_is_locked_sr(flash, status_old, ofs - flash->erase_size,
> +                            flash->erase_size))
> +               return -EINVAL;
> +       /*
> +        * Need largest pow such that:
> +        *
> +        *   1 / (2^pow) >= (len / size)
> +        *
> +        * so (assuming power-of-2 size) we do:
> +        *
> +        *   pow = floor(log2(size / len)) = log2(size) - ceil(log2(len))
> +        */
> +       pow = ilog2(flash->size) - order_base_2(flash->size - (ofs + len));
> +       if (ofs + len == flash->size) {
> +               val = 0; /* fully unlocked */
> +       } else {
> +               val = mask - (pow << shift);
> +               /* Some power-of-two sizes are not supported */
> +               if (val & ~mask)
> +                       return -EINVAL;
> +       }
> +
> +       status_new = (status_old & ~mask) | val;
> +
> +       /* Only modify protection if it will not lock other areas */
> +       if ((status_new & mask) >= (status_old & mask))
> +               return -EINVAL;
> +
> +       spi_flash_cmd_write_status(flash, status_new);
> +
> +       return 0;
> +}
> +#endif  /* CONFIG_SPI_FLASH_STMICRO */
> diff --git a/include/spi_flash.h b/include/spi_flash.h
> index 3b2d555..73b2b0a 100644
> --- a/include/spi_flash.h
> +++ b/include/spi_flash.h
> @@ -31,6 +31,10 @@
>  # define CONFIG_SF_DEFAULT_BUS         0
>  #endif
>
> +#define SR_BP0                 BIT(2)  /* Block protect 0 */
> +#define SR_BP1                 BIT(3)  /* Block protect 1 */
> +#define SR_BP2                 BIT(4)  /* Block protect 2 */
> +

But, these should be in sf_internal.h

>  struct spi_slave;

thanks!
-- 
Jagan | openedev.



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