[PATCH v8 2/3] mtd: spi-nor: spansion: Add support for volatile QE bit

[Pratyush Yadav]

On 21/02/22 04:14PM, tkuw584924 at gmail.com wrote:
> From: Takahiro Kuwano <Takahiro.Kuwano at infineon.com>
> 
> Some of Infineon chips support volatile version of configuration registers
> and it is recommended to update volatile registers in the field application
> due to a risk of the non-volatile registers corruption by power interrupt.
> 
> Signed-off-by: Takahiro Kuwano <Takahiro.Kuwano at infineon.com>
> ---
> Changes in v8:
>   - Use spi_nor_read/write_reg() functions
>   - Use nor->bouncebuf instead of a variable on stack
>   
> Changes in v7:
>   - Add missing macro definitions in v6
>   
> Changes in v6:
>   - Remove multi die package support
> 
> Changes in v5:
>   - No change
>   
> Changes in v4:
>   - No change
>   
> Changes in v3:
>   - Add multi-die package parts support
> 
>  drivers/mtd/spi-nor/spansion.c | 61 ++++++++++++++++++++++++++++++++++
>  1 file changed, 61 insertions(+)
> 
> diff --git a/drivers/mtd/spi-nor/spansion.c b/drivers/mtd/spi-nor/spansion.c
> index 9040edf7359f..5453b89a1c22 100644
> --- a/drivers/mtd/spi-nor/spansion.c
> +++ b/drivers/mtd/spi-nor/spansion.c
> @@ -10,6 +10,8 @@
>  
>  #define SPINOR_OP_RD_ANY_REG			0x65	/* Read any register */
>  #define SPINOR_OP_WR_ANY_REG			0x71	/* Write any register */
> +#define SPINOR_REG_CYPRESS_CFR1V		0x00800002
> +#define SPINOR_REG_CYPRESS_CFR1V_QUAD_EN	BIT(1)	/* Quad Enable */

You might have to rename function and variable names based on mwalle's 
patches [0], depending on which series goes in first.

Other than this,

Reviewed-by: Pratyush Yadav <p.yadav at ti.com>

>  #define SPINOR_REG_CYPRESS_CFR2V		0x00800003
>  #define SPINOR_REG_CYPRESS_CFR2V_MEMLAT_11_24	0xb
>  #define SPINOR_REG_CYPRESS_CFR3V		0x00800004
> @@ -105,6 +107,65 @@ static int spi_nor_cypress_octal_dtr_dis(struct spi_nor *nor)
>  	return 0;
>  }
>  
> +/**
> + * spansion_quad_enable_volatile() - enable Quad I/O mode in volatile register.
> + * @nor:	pointer to a 'struct spi_nor'
> + * @reg_dummy:	number of dummy bytes for register read
> + *
> + * It is recommended to update volatile registers in the field application due
> + * to a risk of the non-volatile registers corruption by power interrupt. This
> + * function sets Quad Enable bit in CFR1 volatile. If users set the Quad Enable
> + * bit in the CFR1 non-volatile in advance (typically by a Flash programmer
> + * before mounting Flash on PCB), the Quad Enable bit in the CFR1 volatile is
> + * also set during Flash power-up. This function supports multi-die package
> + * parts that require to set the Quad Enable bit in each die.
> + *
> + * Return: 0 on success, -errno otherwise.
> + */
> +static int spansion_quad_enable_volatile(struct spi_nor *nor, u8 reg_dummy)
> +{
> +	struct spi_mem_op op;
> +	u32 reg_addr = SPINOR_REG_CYPRESS_CFR1V;
> +	u8 cfr1v_written;
> +	int ret;
> +
> +	op = (struct spi_mem_op)
> +		SPI_NOR_SPANSION_RD_ANY_REG_OP(nor->addr_width, reg_addr,
> +					       reg_dummy, 1, nor->bouncebuf);
> +	ret = spi_nor_read_reg(nor, &op, SNOR_PROTO_1_1_1);
> +	if (ret)
> +		return ret;
> +
> +	if (nor->bouncebuf[0] & SPINOR_REG_CYPRESS_CFR1V_QUAD_EN)
> +		return 0;
> +
> +	/* Update the Quad Enable bit. */
> +	nor->bouncebuf[0] |= SPINOR_REG_CYPRESS_CFR1V_QUAD_EN;
> +	op = (struct spi_mem_op)
> +		SPI_NOR_SPANSION_WR_ANY_REG_OP(nor->addr_width, reg_addr,
> +					       1, nor->bouncebuf);
> +	ret = spi_nor_write_reg(nor, &op, SNOR_PROTO_1_1_1);
> +	if (ret)
> +		return ret;
> +
> +	cfr1v_written = nor->bouncebuf[0];
> +
> +	/* Read back and check it. */
> +	op = (struct spi_mem_op)
> +		SPI_NOR_SPANSION_RD_ANY_REG_OP(nor->addr_width, reg_addr,
> +					       reg_dummy, 1, nor->bouncebuf);
> +	ret = spi_nor_read_reg(nor, &op, SNOR_PROTO_1_1_1);
> +	if (ret)
> +		return ret;
> +
> +	if (nor->bouncebuf[0] != cfr1v_written) {
> +		dev_err(nor->dev, "CFR1: Read back test failed\n");
> +		return -EIO;
> +	}
> +
> +	return 0;
> +}
> +
>  /**
>   * spi_nor_cypress_octal_dtr_enable() - Enable octal DTR on Cypress flashes.
>   * @nor:		pointer to a 'struct spi_nor'
> -- 
> 2.25.1
> 

[0] https://patchwork.ozlabs.org/project/linux-mtd/patch/20220223134358.1914798-13-michael@walle.cc/

-- 
Regards,
Pratyush Yadav
Texas Instruments Inc.