Re: [PATCH v2 1/2] mtd: spi-nor: macronix: add support for Macronix octaflash

[Miquel Raynal <miquel.raynal@bootlin.com>]

Hello,

zhengxunli <zhengxunli@mxic.com.tw> wrote on Fri,  5 Feb 2021 17:36:47
+0800:

> The ocatflash is an xSPI compliant octal DTR flash. Add support
> for using it in octal DTR mode.
> 
> Enable Octal DTR mode with 20 dummy cycles to allow running at the
> maximum supported frequency of 200Mhz.
> 
> Try to verify the flash ID to check whether the flash memory in octal
> DTR mode is correct. When reading ID in OCTAL DTR mode, ID will appear
> in a repeated manner. ex: ID[0] = 0xc2, ID[1] = 0xc2, ID[2] = 0x94,
> ID[3] = 0x94... Rearrange the order so that the ID can pass.
> 
> Signed-off-by: zhengxunli <zhengxunli@mxic.com.tw>
> ---
>  drivers/mtd/spi-nor/macronix.c | 121 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 121 insertions(+)
> 
> diff --git a/drivers/mtd/spi-nor/macronix.c b/drivers/mtd/spi-nor/macronix.c
> index 9203aba..7498978 100644
> --- a/drivers/mtd/spi-nor/macronix.c
> +++ b/drivers/mtd/spi-nor/macronix.c
> @@ -8,6 +8,16 @@
>  
>  #include "core.h"
>  
> +#define SPINOR_OP_RD_CR2		0x71		/* Read configuration register 2 */
> +#define SPINOR_OP_WR_CR2		0x72		/* Write configuration register 2 */
> +#define SPINOR_OP_MXIC_DTR_RD		0xee		/* Fast Read opcode in DTR mode */
> +#define SPINOR_REG_MXIC_CR2_MODE	0x00000000	/* For setting octal DTR mode */
> +#define SPINOR_REG_MXIC_OPI_DTR_EN	0x2		/* Enable Octal DTR */
> +#define SPINOR_REG_MXIC_OPI_DTR_DIS	0x1		/* Disable Octal DTR */
> +#define SPINOR_REG_MXIC_CR2_DC		0x00000300	/* For setting dummy cycles */
> +#define SPINOR_REG_MXIC_DC_20		0x0		/* Setting dummy cycles to 20 */
> +#define MXIC_MAX_DC			20		/* Maximum value of dummy cycles */
> +
>  static int
>  mx25l25635_post_bfpt_fixups(struct spi_nor *nor,
>  			    const struct sfdp_parameter_header *bfpt_header,
> @@ -33,6 +43,113 @@
>  	.post_bfpt = mx25l25635_post_bfpt_fixups,
>  };
>  
> +/**
> + * spi_nor_macronix_octal_dtr_enable() - Enable octal DTR on Macronix flashes.
> + * @nor:		pointer to a 'struct spi_nor'
> + * @enable:		whether to enable or disable Octal DTR
> + *
> + * This also sets the memory access dummy cycles to 20 to allow the flash to
> + * run at up to 200MHz.
> + *
> + * Return: 0 on success, -errno otherwise.
> + */
> +static int spi_nor_macronix_octal_dtr_enable(struct spi_nor *nor, bool enable)
> +{
> +	struct spi_mem_op op;
> +	u8 *buf = nor->bouncebuf, i;
> +	int ret;
> +
> +	if (enable) {
> +		/* Use 20 dummy cycles for memory array reads. */
> +		ret = spi_nor_write_enable(nor);
> +		if (ret)
> +			return ret;
> +
> +		*buf = SPINOR_REG_MXIC_DC_20;
> +		op = (struct spi_mem_op)
> +			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_WR_CR2, 1),
> +				   SPI_MEM_OP_ADDR(4, SPINOR_REG_MXIC_CR2_DC, 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;
> +
> +		nor->read_dummy = MXIC_MAX_DC;

I am still not convinced by this constant value.

The rest looks good to me.


Thanks,
Miquèl