Re: [PATCH v14 15/15] mtd: spi-nor: micron-st: allow using MT35XU512ABA in Octal DTR mode

[Tudor.Ambarus]

On 9/30/20 9:57 PM, Pratyush Yadav wrote:
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> 
> Since this flash doesn't have a Profile 1.0 table, the Octal DTR
> capabilities are enabled in the post SFDP fixup, along with the 8D-8D-8D
> fast read settings.
> 
> Enable Octal DTR mode with 20 dummy cycles to allow running at the
> maximum supported frequency of 200Mhz.
> 
> The flash supports the soft reset sequence. So, add the flag in the
> flash's info.
> 
> Signed-off-by: Pratyush Yadav <p.yadav@xxxxxx>
> ---
>  drivers/mtd/spi-nor/micron-st.c | 100 +++++++++++++++++++++++++++++++-
>  1 file changed, 99 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/spi-nor/micron-st.c b/drivers/mtd/spi-nor/micron-st.c
> index ef3695080710..b0002c29fd37 100644
> --- a/drivers/mtd/spi-nor/micron-st.c
> +++ b/drivers/mtd/spi-nor/micron-st.c
> @@ -8,10 +8,108 @@
> 
>  #include "core.h"
> 
> +#define SPINOR_OP_MT_DTR_RD    0xfd    /* Fast Read opcode in DTR mode */
> +#define SPINOR_OP_MT_RD_ANY_REG        0x85    /* Read volatile register */
> +#define SPINOR_OP_MT_WR_ANY_REG        0x81    /* Write volatile register */
> +#define SPINOR_REG_MT_CFR0V    0x00    /* For setting octal DTR mode */
> +#define SPINOR_REG_MT_CFR1V    0x01    /* For setting dummy cycles */
> +#define SPINOR_MT_OCT_DTR      0xe7    /* Enable Octal DTR. */
> +#define SPINOR_MT_EXSPI                0xff    /* Enable Extended SPI (default) */
> +
> +static int spi_nor_micron_octal_dtr_enable(struct spi_nor *nor, bool enable)
> +{
> +       struct spi_mem_op op;
> +       u8 *buf = nor->bouncebuf;
> +       int ret;
> +
> +       if (enable) {
> +               /* Use 20 dummy cycles for memory array reads. */
> +               ret = spi_nor_write_enable(nor);
> +               if (ret)
> +                       return ret;
> +
> +               *buf = 20;
> +               op = (struct spi_mem_op)
> +                       SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_MT_WR_ANY_REG, 1),
> +                                  SPI_MEM_OP_ADDR(3, SPINOR_REG_MT_CFR1V, 1),
> +                                  SPI_MEM_OP_NO_DUMMY,
> +                                  SPI_MEM_OP_DATA_OUT(1, buf, 1));
> +
> +               ret = spi_mem_exec_op(nor->spimem, &op);
> +               if (ret)
> +                       return ret;
> +
> +               ret = spi_nor_wait_till_ready(nor);
> +               if (ret)
> +                       return ret;
> +       }
> +
> +       ret = spi_nor_write_enable(nor);
> +       if (ret)
> +               return ret;
> +
> +       if (enable)
> +               *buf = SPINOR_MT_OCT_DTR;
> +       else
> +               *buf = SPINOR_MT_EXSPI;
> +
> +       op = (struct spi_mem_op)
> +               SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_MT_WR_ANY_REG, 1),
> +                          SPI_MEM_OP_ADDR(enable ? 3 : 4,
> +                                          SPINOR_REG_MT_CFR0V, 1),
> +                          SPI_MEM_OP_NO_DUMMY,
> +                          SPI_MEM_OP_DATA_OUT(1, buf, 1));
> +
> +       if (!enable)
> +               spi_nor_spimem_setup_op(nor, &op, SNOR_PROTO_8_8_8_DTR);
> +
> +       ret = spi_mem_exec_op(nor->spimem, &op);
> +       if (ret)
> +               return ret;
> +
> +       /* Give some time for the mode change to take place. */
> +       usleep_range(400, 600);

Don't we need to still read the Status Register here? The same question
applies for the previous patch.

> +
> +       return 0;
> +}
> +
> +static void mt35xu512aba_default_init(struct spi_nor *nor)
> +{
> +       nor->params->octal_dtr_enable = spi_nor_micron_octal_dtr_enable;
> +}
> +
> +static void mt35xu512aba_post_sfdp_fixup(struct spi_nor *nor)
> +{
> +       /* Set the Fast Read settings. */
> +       nor->params->hwcaps.mask |= SNOR_HWCAPS_READ_8_8_8_DTR;
> +       spi_nor_set_read_settings(&nor->params->reads[SNOR_CMD_READ_8_8_8_DTR],
> +                                 0, 20, SPINOR_OP_MT_DTR_RD,
> +                                 SNOR_PROTO_8_8_8_DTR);
> +
> +       nor->cmd_ext_type = SPI_NOR_EXT_REPEAT;
> +       nor->params->rdsr_dummy = 8;
> +       nor->params->rdsr_addr_nbytes = 0;
> +
> +       /*
> +        * The BFPT quad enable field is set to a reserved value so the quad
> +        * enable function is ignored by spi_nor_parse_bfpt(). Make sure we
> +        * disable it.
> +        */
> +       nor->params->quad_enable = NULL;
> +}
> +
> +static struct spi_nor_fixups mt35xu512aba_fixups = {
> +       .default_init = mt35xu512aba_default_init,
> +       .post_sfdp = mt35xu512aba_post_sfdp_fixup,
> +};
> +
>  static const struct flash_info micron_parts[] = {
>         { "mt35xu512aba", INFO(0x2c5b1a, 0, 128 * 1024, 512,
>                                SECT_4K | USE_FSR | SPI_NOR_OCTAL_READ |
> -                              SPI_NOR_4B_OPCODES) },
> +                              SPI_NOR_4B_OPCODES | SPI_NOR_OCTAL_DTR_READ |
> +                              SPI_NOR_OCTAL_DTR_PP |
> +                              SPI_NOR_IO_MODE_EN_VOLATILE)
> +         .fixups = &mt35xu512aba_fixups},
>         { "mt35xu02g", INFO(0x2c5b1c, 0, 128 * 1024, 2048,
>                             SECT_4K | USE_FSR | SPI_NOR_OCTAL_READ |
>                             SPI_NOR_4B_OPCODES) },
> --
> 2.28.0
>