[PATCH v3 3/4] spi-nor: Adapt soft reset to XTX25F32B in Rock Pi 4 rev 1.4

[Pratyush Yadav]

On 20/07/22 05:42PM, Xavier Drudis Ferran wrote:
> XTX25F32B does not use octal mode and accepts soft reset, despite its
> SFDP tables. Soft reset at U-Boot exit seems to be required to write
> to /dev/mtd0 from flashrom in linux. Soft reset at U-Boot start seems
> to help booting from SPI (at least with the dts properties I'm using).
> 
> The first soft reset is done before the flash id is read and the
> fixups can be called, and v1 of this patch would now fail in Rock Pi 4
> because of unsupported operation if tried with
> SNOR_PROTO_8_8_8_DTR. This was since commit 5752d6ae8daa ("spi:
> spi-mem: add spi_mem_dtr_supports_op()") by Pratyush Yadav.
> 
> So try a few modes until SNOR_PROTO_1_1_1 works and then remember the
> reset_proto.  This tries to be useful for other boards, but I still
> don't know any other that needs it and what would work there.
> 
> Changed since v2: 
> 
>    - none (rebase)
> 
> Changed since v1:
> 
>    - Generalization. First soft reset with SNOR_PROTO_8_8_8_DTR stopped
>      working since the improvement by Pratyush Yadav.
>      Instead of trying 8_8_8_DTR always at first reset, and force
>      1_1_1 once XTX25F32B is detected (so, for last reset) do
>      a generic loop for any chip trying protocols until one is
>      supported and starting by the 8_8_8_DTR protocol (the one previously
>      used). This leverages the fixed supports_op() to take into account
>      controller and device.

Please don't put the changelog in the commit message. Put it below the 3 
dashed lines below.

> 
> fixups can be called, and it would now fail in Rock Pi 4 because of
> unsupported operation if tried with SNOR_PROTO_8_8_8_DTR. So try a few
> modes until SNOR_PROTO_1_1_1 works and then remember the reset_proto.
> This tries to be useful for other boards, but I still don't know any
> other that needs it and what would work there.
> 
> Signed-off-by: Xavier Drudis Ferran <xdrudis at tinet.cat>
> 
> Cc: Jagan Teki <jagan at amarulasolutions.com>
> Cc: Vignesh R <vigneshr at ti.com>
> 
> ---
>  drivers/mtd/spi/spi-nor-core.c | 98 ++++++++++++++++++++++++++++++----
>  include/linux/mtd/spi-nor.h    |  5 ++
>  2 files changed, 92 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
> index 8a226a7af5..17f0cb51fb 100644
> --- a/drivers/mtd/spi/spi-nor-core.c
> +++ b/drivers/mtd/spi/spi-nor-core.c
> @@ -3575,6 +3575,18 @@ static struct spi_nor_fixups mt35xu512aba_fixups = {
>  };
>  #endif /* CONFIG_SPI_FLASH_MT35XU */
>  
> +#ifdef CONFIG_SPI_FLASH_XTX
> +static void xtx25f32b_post_sfdp_fixup(struct spi_nor *nor,
> +				      struct spi_nor_flash_parameter *params)
> +{
> +	nor->flags |= SNOR_F_SOFT_RESET;
> +}
> +
> +static struct spi_nor_fixups xtx25f32b_fixups = {
> +	.post_sfdp = xtx25f32b_post_sfdp_fixup,
> +};
> +#endif
> +
>  #if CONFIG_IS_ENABLED(SPI_FLASH_MACRONIX)
>  /**
>   * spi_nor_macronix_octal_dtr_enable() - Enable octal DTR on Macronix flashes.
> @@ -3733,6 +3745,53 @@ static int spi_nor_init(struct spi_nor *nor)
>  }
>  
>  #ifdef CONFIG_SPI_FLASH_SOFT_RESET
> +/**
> + * spi_nor_soft_reset_setup_op() - Initial setup of op for soft
> + * reset. Initializes nor->reset_proto iff needed.
> + *
> + * @nor:	the spi_nor structure nor->reset_proto will be used or if
> + *		null, it'll be assigned the used protocol, from a few
> + *		protocols that get tried for device and controller
> + *		support.
> + *
> + * @opcode	operation code for soft reset (or soft reset enable,
> + *		we currently assume they work the same in all systems)
> + *
> + * @op:	pointer to operation struct to set up for reset or reset
> + *		enable.
> + */
> +static void spi_nor_soft_reset_setup_op(struct spi_nor *nor, u16 opcode, struct spi_mem_op *op)
> +{
> +	enum spi_nor_protocol reset_proto;
> +	/**
> +	 *  admitedly arbitrary list, to be improved if there's
> +	 *  new knowledge of what works in different systems
> +	 */
> +	enum spi_nor_protocol reset_proto_candidates[] = {
> +		SNOR_PROTO_8_8_8_DTR, SNOR_PROTO_1_1_1_DTR, SNOR_PROTO_8_8_8,
> +		SNOR_PROTO_4_4_4,  SNOR_PROTO_2_2_2, SNOR_PROTO_1_1_1
> +	};
> +
> +	if (nor->reset_proto) {
> +		*op = (struct spi_mem_op)SPI_MEM_OP(SPI_MEM_OP_CMD(opcode, 0),
> +						    SPI_MEM_OP_NO_DUMMY,
> +						    SPI_MEM_OP_NO_ADDR,
> +						    SPI_MEM_OP_NO_DATA);
> +		spi_nor_setup_op(nor, op, nor->reset_proto);
> +	} else {
> +		for (int i = 0; i < ARRAY_SIZE(reset_proto_candidates) && !nor->reset_proto ; i++) {
> +			reset_proto = reset_proto_candidates[i];
> +			*op = (struct spi_mem_op)SPI_MEM_OP(SPI_MEM_OP_CMD(opcode, 0),
> +							    SPI_MEM_OP_NO_DUMMY,
> +							    SPI_MEM_OP_NO_ADDR,
> +							    SPI_MEM_OP_NO_DATA);
> +			spi_nor_setup_op(nor, op, reset_proto);
> +			if (spi_mem_supports_op(nor->spi, op))

This only tells if the _controller_ supports the op. There is no way to 
find out if the flash supports the op without reading SFDP, which would 
need you to either reset the flash or know which mode it is in. So this 
patch is all wrong.

The only way to find out what the flash supports is to read its ID or 
SFDP.

> +				nor->reset_proto = reset_proto;
> +		}
> +	}
> +}
> +
>  /**
>   * spi_nor_soft_reset() - perform the JEDEC Software Reset sequence
>   * @nor:	the spi_nor structure
> @@ -3756,11 +3815,7 @@ static int spi_nor_soft_reset(struct spi_nor *nor)
>  #endif /* SPI_NOR_BOOT_SOFT_RESET_EXT_INVERT */
>  	}
>  
> -	op = (struct spi_mem_op)SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_SRSTEN, 0),
> -			SPI_MEM_OP_NO_DUMMY,
> -			SPI_MEM_OP_NO_ADDR,
> -			SPI_MEM_OP_NO_DATA);
> -	spi_nor_setup_op(nor, &op, SNOR_PROTO_8_8_8_DTR);
> +	spi_nor_soft_reset_setup_op(nor, SPINOR_OP_SRSTEN, &op);
>  	ret = spi_mem_exec_op(nor->spi, &op);
>  	if (ret) {
>  		dev_warn(nor->dev, "Software reset enable failed: %d\n", ret);
> @@ -3771,7 +3826,7 @@ static int spi_nor_soft_reset(struct spi_nor *nor)
>  			SPI_MEM_OP_NO_DUMMY,
>  			SPI_MEM_OP_NO_ADDR,
>  			SPI_MEM_OP_NO_DATA);
> -	spi_nor_setup_op(nor, &op, SNOR_PROTO_8_8_8_DTR);
> +	spi_nor_setup_op(nor, &op, nor->reset_proto);
>  	ret = spi_mem_exec_op(nor->spi, &op);
>  	if (ret) {
>  		dev_warn(nor->dev, "Software reset failed: %d\n", ret);
> @@ -3789,18 +3844,34 @@ out:
>  	nor->cmd_ext_type = ext;
>  	return ret;
>  }
> -#endif /* CONFIG_SPI_FLASH_SOFT_RESET */
> +
> +static bool flash_supports_proto(const struct flash_info *flash,  enum spi_nor_protocol proto)
> +{
> +	switch (spi_nor_get_protocol_data_nbits(proto)) {
> +	case 8:
> +		return flash->flags & (spi_nor_protocol_is_dtr(proto)
> +				       ? SPI_NOR_OCTAL_DTR_READ
> +				       : SPI_NOR_OCTAL_READ);
> +	case 4:	return flash->flags & SPI_NOR_QUAD_READ;
> +	case 2: return flash->flags & SPI_NOR_DUAL_READ;
> +	default:
> +		return 1;
> +	}
> +}
>  
>  int spi_nor_remove(struct spi_nor *nor)
>  {
> -#ifdef CONFIG_SPI_FLASH_SOFT_RESET
> -	if (nor->info->flags & SPI_NOR_OCTAL_DTR_READ &&
> +	if (flash_supports_proto(nor->info, nor->reset_proto) &&
>  	    nor->flags & SNOR_F_SOFT_RESET)
>  		return spi_nor_soft_reset(nor);
> -#endif
> -
>  	return 0;
>  }
> +#else /* !CONFIG_SPI_FLASH_SOFT_RESET */
> +int spi_nor_remove(struct spi_nor *nor)
> +{
> +	return 0;
> +}
> +#endif /* CONFIG_SPI_FLASH_SOFT_RESET */
>  
>  void spi_nor_set_fixups(struct spi_nor *nor)
>  {
> @@ -3835,6 +3906,11 @@ void spi_nor_set_fixups(struct spi_nor *nor)
>  #if CONFIG_IS_ENABLED(SPI_FLASH_MACRONIX)
>  	nor->fixups = &macronix_octal_fixups;
>  #endif /* SPI_FLASH_MACRONIX */
> +
> +#ifdef CONFIG_SPI_FLASH_XTX
> +	if (!strcmp(nor->info->name, "xt25f32b"))
> +		nor->fixups = &xtx25f32b_fixups;
> +#endif
>  }
>  
>  int spi_nor_scan(struct spi_nor *nor)
> diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
> index 2595bad9df..4fc81e7b8d 100644
> --- a/include/linux/mtd/spi-nor.h
> +++ b/include/linux/mtd/spi-nor.h
> @@ -501,6 +501,8 @@ struct spi_flash {
>   * @read_proto:		the SPI protocol for read operations
>   * @write_proto:	the SPI protocol for write operations
>   * @reg_proto		the SPI protocol for read_reg/write_reg/erase operations
> + * @reset_proto:	The SPI protocol for soft reset to return to state expected
> + *			by OS before running the OS (at remove time) or at sf probe
>   * @cmd_buf:		used by the write_reg
>   * @cmd_ext_type:	the command opcode extension for DTR mode.
>   * @fixups:		flash-specific fixup hooks.
> @@ -546,6 +548,9 @@ struct spi_nor {
>  	enum spi_nor_protocol	read_proto;
>  	enum spi_nor_protocol	write_proto;
>  	enum spi_nor_protocol	reg_proto;
> +#ifdef CONFIG_SPI_FLASH_SOFT_RESET
> +	enum spi_nor_protocol	reset_proto;
> +#endif
>  	bool			sst_write_second;
>  	u32			flags;
>  	u8			cmd_buf[SPI_NOR_MAX_CMD_SIZE];
> -- 
> 2.20.1
> 

-- 
Regards,
Pratyush Yadav
Texas Instruments Inc.