Re: [PATCH linux-next v6 1/8] mtd: spi-nor: read JEDEC ID with multiple I/O protocols

[Jonas Gorski <jogo-p3rKhJxN3npAfugRpC6u6w@public.gmane.org>]

Hi,

On Wed, Sep 9, 2015 at 3:24 PM, Cyrille Pitchen
<cyrille.pitchen-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org> wrote:
> When their quad or dual I/O mode is enabled, Micron and Macronix spi-nor
> memories don't reply to the regular Read ID (0x9f) command. Instead they
> reply to a new dedicated command Read ID Multiple I/O (0xaf).
>
> If the Read ID (0x9f) command fails (the read ID is all 1's or all 0's),
> then the Read ID Multiple I/O (0xaf) is used, first with SPI 4-4-4 protocol
> (supported by both Micron and Macronix memories), lately with SPI-2-2-2
> protocol (supported only by Micron memories).
>
> Signed-off-by: Cyrille Pitchen <cyrille.pitchen-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org>
> ---
>  drivers/mtd/spi-nor/spi-nor.c | 28 +++++++++++++++++++++++++++-
>  include/linux/mtd/spi-nor.h   | 23 +++++++++++++++++++++--
>  2 files changed, 48 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> index f59aedfe1462..80a0db078aaa 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -703,8 +703,9 @@ static const struct flash_info spi_nor_ids[] = {
>
>  static const struct flash_info *spi_nor_read_id(struct spi_nor *nor)
>  {
> -       int                     tmp;
> +       int                     i, tmp;
>         u8                      id[SPI_NOR_MAX_ID_LEN];
> +       enum spi_protocol       proto[2] = {SPI_PROTO_4_4_4, SPI_PROTO_2_2_2};
>         const struct flash_info *info;
>
>         tmp = nor->read_reg(nor, SPINOR_OP_RDID, id, SPI_NOR_MAX_ID_LEN);
> @@ -713,6 +714,25 @@ static const struct flash_info *spi_nor_read_id(struct spi_nor *nor)
>                 return ERR_PTR(tmp);
>         }
>
> +       /* Special case for Micron/Macronix qspi nor. */
> +       for (i = 0; i < ARRAY_SIZE(proto); ++i) {
> +               if (!((id[0] == 0xff && id[1] == 0xff && id[2] == 0xff) ||
> +                     (id[0] == 0x00 && id[1] == 0x00 && id[2] == 0x00)))
> +                       break;

you should probably do something like

               if (proto == SPI_PROTO_2_2_2 && !(nor->flags & SPI_NOR_DUAL))
                              continue;

               if (proto == SPI_PROTO_4_4_4 && !(nor->flags & SPI_NOR_QUAD))
                              continue;
> +
> +               nor->erase_proto = proto[i];
> +               nor->read_proto = proto[i];
> +               nor->write_proto = proto[i];
> +               nor->reg_proto = proto[i];
> +               tmp = nor->read_reg(nor, SPINOR_OP_MIO_RDID,
> +                                   id, SPI_NOR_MAX_ID_LEN);

Not sure if it has any releveance that the MIO_RDID commands can only
return the first three id bytes, and not the full id.

> +               if (tmp < 0) {
> +                       dev_dbg(nor->dev,
> +                               " error %d reading JEDEC ID (MULTI IO)\n", tmp);
> +                       return ERR_PTR(tmp);

Or continue here, as the controller might return an error if it does
not support the protocol.

> +               }
> +       }
> +
>         for (tmp = 0; tmp < ARRAY_SIZE(spi_nor_ids) - 1; tmp++) {
>                 info = &spi_nor_ids[tmp];
>                 if (info->id_len) {
> @@ -1013,6 +1033,12 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode)
>         if (ret)
>                 return ret;
>
> +       /* Reset SPI protocol for all commands */
> +       nor->erase_proto = SPI_PROTO_1_1_1;
> +       nor->read_proto = SPI_PROTO_1_1_1;
> +       nor->write_proto = SPI_PROTO_1_1_1;
> +       nor->reg_proto = SPI_PROTO_1_1_1;
> +
>         if (name)
>                 info = spi_nor_match_id(name);
>         /* Try to auto-detect if chip name wasn't specified or not found */
> diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
> index e5409524bb0a..66a5f144728a 100644
> --- a/include/linux/mtd/spi-nor.h
> +++ b/include/linux/mtd/spi-nor.h
> @@ -57,8 +57,9 @@
>  #define SPINOR_OP_BRWR         0x17    /* Bank register write */
>
>  /* Used for Micron flashes only. */
> -#define SPINOR_OP_RD_EVCR      0x65    /* Read EVCR register */
> -#define SPINOR_OP_WD_EVCR      0x61    /* Write EVCR register */
> +#define SPINOR_OP_MIO_RDID     0xaf    /* Multiple I/O Read JEDEC ID */
> +#define SPINOR_OP_RD_EVCR      0x65    /* Read EVCR register */
> +#define SPINOR_OP_WD_EVCR      0x61    /* Write EVCR register */
>
>  /* Status Register bits. */
>  #define SR_WIP                 1       /* Write in progress */
> @@ -87,6 +88,16 @@ enum read_mode {
>         SPI_NOR_QUAD,
>  };
>
> +enum spi_protocol {
> +       SPI_PROTO_1_1_1,        /* SPI */
> +       SPI_PROTO_1_1_2,        /* Dual Output */
> +       SPI_PROTO_1_1_4,        /* Quad Output */
> +       SPI_PROTO_1_2_2,        /* Dual IO */
> +       SPI_PROTO_1_4_4,        /* Quad IO */
> +       SPI_PROTO_2_2_2,        /* Dual Command */
> +       SPI_PROTO_4_4_4,        /* Quad Command */
> +};

I wonder if the spi-nor controller should somehow store which of these
protocols it can support, so we can check for support before using any
of the dual/quad (i/o) commands.

Also I think you should split out the new readid command usage from
the rest of the SPI_PROTO stuff, as they are only semirelated.

And for good definsive programming, you should first make the spi-nor
controller drivers aware of the protocol stuff before starting to use
it, else you risk breaking controllers silently.


> +
>  /**
>   * struct spi_nor_xfer_cfg - Structure for defining a Serial Flash transfer
>   * @wren:              command for "Write Enable", or 0x00 for not required
> @@ -142,6 +153,10 @@ enum spi_nor_option_flags {
>   * @sst_write_second:  used by the SST write operation
>   * @flags:             flag options for the current SPI-NOR (SNOR_F_*)
>   * @cfg:               used by the read_xfer/write_xfer
> + * @erase_proto:       the SPI protocol used by erase operations
> + * @read_proto:                the SPI protocol used by read operations
> + * @write_proto:       the SPI protocol used by write operations
> + * @reg_proto          the SPI protocol used by read_reg/write_reg operations
>   * @cmd_buf:           used by the write_reg
>   * @prepare:           [OPTIONAL] do some preparations for the
>   *                     read/write/erase/lock/unlock operations
> @@ -169,6 +184,10 @@ struct spi_nor {
>         u8                      read_opcode;
>         u8                      read_dummy;
>         u8                      program_opcode;
> +       enum spi_protocol       erase_proto;
> +       enum spi_protocol       read_proto;
> +       enum spi_protocol       write_proto;
> +       enum spi_protocol       reg_proto;
>         enum read_mode          flash_read;
>         bool                    sst_write_second;
>         u32                     flags;



Regards
Jonas
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