Re: [PATCH v3 1/9] hw/block: m25p80: Add ISSI SPI flash support

[Alistair Francis]

On Mon, Jan 25, 2021 at 10:01 PM Bin Meng <bmeng.cn@gmail.com> wrote:
>
> From: Bin Meng <bin.meng@windriver.com>
>
> This adds the ISSI SPI flash support. The number of dummy cycles in
> fast read, fast read dual output and fast read quad output commands
> is currently using the default 8. Likewise, the same default value
> is used for fast read dual/quad I/O command. Per the datasheet [1],
> the number of dummy cycles is configurable, but this is not modeled
> at present.
>
> For flash whose size is larger than 16 MiB, the sequence of 3-byte
> address along with EXTADD bit in the bank address register (BAR) is
> not supported. We assume that guest software always uses op codes
> with 4-byte address sequence. Fortunately, this is the case for both
> U-Boot and Linux spi-nor drivers.
>
> QPI (Quad Peripheral Interface) that supports 2-cycle instruction
> has different default values for dummy cycles of fast read family
> commands, and is unsupported at the time being.
>
> [1] http://www.issi.com/WW/pdf/25LP-WP256.pdf
>
> Signed-off-by: Bin Meng <bin.meng@windriver.com>

Acked-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

>
> ---
>
> (no changes since v2)
>
> Changes in v2:
> - Mention QPI (Quad Peripheral Interface) mode is not supported
>
>  hw/block/m25p80.c | 44 +++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 43 insertions(+), 1 deletion(-)
>
> diff --git a/hw/block/m25p80.c b/hw/block/m25p80.c
> index b744a58d1c..217c130f56 100644
> --- a/hw/block/m25p80.c
> +++ b/hw/block/m25p80.c
> @@ -412,6 +412,7 @@ typedef enum {
>      MAN_NUMONYX,
>      MAN_WINBOND,
>      MAN_SST,
> +    MAN_ISSI,
>      MAN_GENERIC,
>  } Manufacturer;
>
> @@ -487,6 +488,8 @@ static inline Manufacturer get_man(Flash *s)
>          return MAN_MACRONIX;
>      case 0xBF:
>          return MAN_SST;
> +    case 0x9D:
> +        return MAN_ISSI;
>      default:
>          return MAN_GENERIC;
>      }
> @@ -706,6 +709,9 @@ static void complete_collecting_data(Flash *s)
>          case MAN_SPANSION:
>              s->quad_enable = !!(s->data[1] & 0x02);
>              break;
> +        case MAN_ISSI:
> +            s->quad_enable = extract32(s->data[0], 6, 1);
> +            break;
>          case MAN_MACRONIX:
>              s->quad_enable = extract32(s->data[0], 6, 1);
>              if (s->len > 1) {
> @@ -895,6 +901,19 @@ static void decode_fast_read_cmd(Flash *s)
>                                      SPANSION_DUMMY_CLK_LEN
>                                      );
>          break;
> +    case MAN_ISSI:
> +        /*
> +         * The Fast Read instruction code is followed by address bytes and
> +         * dummy cycles, transmitted via the SI line.
> +         *
> +         * The number of dummy cycles is configurable but this is currently
> +         * unmodeled, hence the default value 8 is used.
> +         *
> +         * QPI (Quad Peripheral Interface) mode has different default value
> +         * of dummy cycles, but this is unsupported at the time being.
> +         */
> +        s->needed_bytes += 1;
> +        break;
>      default:
>          break;
>      }
> @@ -934,6 +953,16 @@ static void decode_dio_read_cmd(Flash *s)
>              break;
>          }
>          break;
> +    case MAN_ISSI:
> +        /*
> +         * The Fast Read Dual I/O instruction code is followed by address 
> bytes
> +         * and dummy cycles, transmitted via the IO1 and IO0 line.
> +         *
> +         * The number of dummy cycles is configurable but this is currently
> +         * unmodeled, hence the default value 4 is used.
> +         */
> +        s->needed_bytes += 1;
> +        break;
>      default:
>          break;
>      }
> @@ -974,6 +1003,19 @@ static void decode_qio_read_cmd(Flash *s)
>              break;
>          }
>          break;
> +    case MAN_ISSI:
> +        /*
> +         * The Fast Read Quad I/O instruction code is followed by address 
> bytes
> +         * and dummy cycles, transmitted via the IO3, IO2, IO1 and IO0 line.
> +         *
> +         * The number of dummy cycles is configurable but this is currently
> +         * unmodeled, hence the default value 6 is used.
> +         *
> +         * QPI (Quad Peripheral Interface) mode has different default value
> +         * of dummy cycles, but this is unsupported at the time being.
> +         */
> +        s->needed_bytes += 3;
> +        break;
>      default:
>          break;
>      }
> @@ -1132,7 +1174,7 @@ static void decode_new_cmd(Flash *s, uint32_t value)
>
>      case RDSR:
>          s->data[0] = (!!s->write_enable) << 1;
> -        if (get_man(s) == MAN_MACRONIX) {
> +        if (get_man(s) == MAN_MACRONIX || get_man(s) == MAN_ISSI) {
>              s->data[0] |= (!!s->quad_enable) << 6;
>          }
>          if (get_man(s) == MAN_SST) {
> --
> 2.25.1
>
>