linux-kernel - Re: [PATCH 2/5] mtd: spi-nor: group the code about the write protection at power-up

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Date:   Mon, 5 Aug 2019 11:14:17 +0530
From:   Vignesh Raghavendra <vigneshr@...com>
To:     <Tudor.Ambarus@...rochip.com>, <marek.vasut@...il.com>
CC:     <dwmw2@...radead.org>, <computersforpeace@...il.com>,
        <miquel.raynal@...tlin.com>, <richard@....at>,
        <boris.brezillon@...labora.com>, <linux-mtd@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <Nicolas.Ferre@...rochip.com>
Subject: Re: [PATCH 2/5] mtd: spi-nor: group the code about the write
 protection at power-up



On 17/07/19 2:18 PM, Tudor.Ambarus@...rochip.com wrote:
> From: Tudor Ambarus <tudor.ambarus@...rochip.com>
> 
> The write protection at power-up logic was split across functions
> because of a dependency to spansion_quad_enable(). Group the code
> in spi_nor_init() as the pointer to spansion_quad_enable() can be
> retrieved from nor->quad_enable.
> 
> While touching this code, rename nor->clear_sr_bp() to
> nor->disable_write_protection() to better indicate its scope: it
> disables the default write protection after a power-on reset cycle.

I prefer this function to be renamed to nor->disable_block_protection()
so as to avoid being confused with write protect signal input to the flash.

Regards
Vignesh

> 
> No functional change intended.
> 
> Signed-off-by: Tudor Ambarus <tudor.ambarus@...rochip.com>
> ---
>  drivers/mtd/spi-nor/spi-nor.c | 39 ++++++++++++++++++++++++---------------
>  include/linux/mtd/spi-nor.h   |  6 +++---
>  2 files changed, 27 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> index 03cc788511d5..e9e441f91b68 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -3780,8 +3780,6 @@ static int spi_nor_init_params(struct spi_nor *nor,
>  		default:
>  			/* Kept only for backward compatibility purpose. */
>  			params->quad_enable = spansion_quad_enable;
> -			if (nor->clear_sr_bp)
> -				nor->clear_sr_bp = spi_nor_spansion_clear_sr_bp;
>  			break;
>  		}
>  
> @@ -4034,11 +4032,32 @@ static int spi_nor_init(struct spi_nor *nor)
>  {
>  	int err;
>  
> -	if (nor->clear_sr_bp) {
> -		err = nor->clear_sr_bp(nor);
> +	/*
> +	 * Atmel, SST, Intel/Numonyx, and others serial NOR tend to power up
> +	 * with the software protection bits set.
> +	 */
> +	if (JEDEC_MFR(nor->info) == SNOR_MFR_ATMEL ||
> +	    JEDEC_MFR(nor->info) == SNOR_MFR_INTEL ||
> +	    JEDEC_MFR(nor->info) == SNOR_MFR_SST ||
> +	    nor->info->flags & SPI_NOR_HAS_LOCK) {
> +		nor->disable_write_protection = spi_nor_clear_sr_bp;
> +
> +		/*
> +		 * In case of spansion flashes, when the configuration register
> +		 * Quad Enable bit is one, only the the Write Status (01h)
> +		 * command with two data bytes may be used to clear the block
> +		 * protection bits.
> +		 */
> +		if (nor->quad_enable == spansion_quad_enable)
> +			nor->disable_write_protection =
> +				spi_nor_spansion_clear_sr_bp;
> +	}
> +
> +	if (nor->disable_write_protection) {
> +		err = nor->disable_write_protection(nor);
>  		if (err) {
>  			dev_err(nor->dev,
> -				"fail to clear block protection bits\n");
> +				"failed to unlock the flash at init\n");
>  			return err;
>  		}
>  	}
> @@ -4165,16 +4184,6 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
>  	if (info->flags & SPI_S3AN)
>  		nor->flags |=  SNOR_F_READY_XSR_RDY;
>  
> -	/*
> -	 * Atmel, SST, Intel/Numonyx, and others serial NOR tend to power up
> -	 * with the software protection bits set.
> -	 */
> -	if (JEDEC_MFR(nor->info) == SNOR_MFR_ATMEL ||
> -	    JEDEC_MFR(nor->info) == SNOR_MFR_INTEL ||
> -	    JEDEC_MFR(nor->info) == SNOR_MFR_SST ||
> -	    nor->info->flags & SPI_NOR_HAS_LOCK)
> -		nor->clear_sr_bp = spi_nor_clear_sr_bp;
> -
>  	/* Parse the Serial Flash Discoverable Parameters table. */
>  	ret = spi_nor_init_params(nor, &params);
>  	if (ret)
> diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
> index c4c2c5971284..6c3273760700 100644
> --- a/include/linux/mtd/spi-nor.h
> +++ b/include/linux/mtd/spi-nor.h
> @@ -374,8 +374,8 @@ struct flash_info;
>   * @flash_is_locked:	[FLASH-SPECIFIC] check if a region of the SPI NOR is
>   *			completely locked
>   * @quad_enable:	[FLASH-SPECIFIC] enables SPI NOR quad mode
> - * @clear_sr_bp:	[FLASH-SPECIFIC] clears the Block Protection Bits from
> - *			the SPI NOR Status Register.
> + * @disable_write_protection: [FLASH-SPECIFIC] disable write protection during
> + *                            power-up
>   * @priv:		the private data
>   */
>  struct spi_nor {
> @@ -412,7 +412,7 @@ struct spi_nor {
>  	int (*flash_unlock)(struct spi_nor *nor, loff_t ofs, uint64_t len);
>  	int (*flash_is_locked)(struct spi_nor *nor, loff_t ofs, uint64_t len);
>  	int (*quad_enable)(struct spi_nor *nor);
> -	int (*clear_sr_bp)(struct spi_nor *nor);
> +	int (*disable_write_protection)(struct spi_nor *nor);
>  
>  	void *priv;
>  };
> 

-- 
Regards
Vignesh