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Date:   Sun, 25 Aug 2019 15:09:27 +0200
From:   Boris Brezillon <boris.brezillon@collabora.com>
To:     <Tudor.Ambarus@microchip.com>
Cc:     <marek.vasut@gmail.com>, <vigneshr@ti.com>,
        <miquel.raynal@bootlin.com>, <richard@nod.at>,
        <linux-mtd@lists.infradead.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 4/5] mtd: spi-nor: Move clear_sr_bp() to 'struct
 spi_nor_flash_parameter'
Message-ID: <20190825150927.5374b1ea@collabora.com>
In-Reply-To: <20190823155325.13459-5-tudor.ambarus@microchip.com>
References: <20190823155325.13459-1-tudor.ambarus@microchip.com>
        <20190823155325.13459-5-tudor.ambarus@microchip.com>
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On Fri, 23 Aug 2019 15:53:41 +0000
<Tudor.Ambarus@microchip.com> wrote:

> From: Tudor Ambarus <tudor.ambarus@microchip.com>
> 
> All flash parameters and settings should reside inside
> 'struct spi_nor_flash_parameter'. Move clear_sr_bp() from
> 'struct spi_nor' to 'struct spi_nor_flash_parameter'.
> 
> Rename clear_sr_bp()/disable_block_protection() to better indicate
> what the function does.
> 
> Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
> ---
>  drivers/mtd/spi-nor/spi-nor.c | 47 +++++++++++++++++++++++++++++++++----------
>  include/linux/mtd/spi-nor.h   |  5 ++---
>  2 files changed, 38 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> index 6bd104c29cd9..15b0b1148bf3 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -4477,20 +4477,45 @@ static int spi_nor_quad_enable(struct spi_nor *nor)
>  	return nor->params.quad_enable(nor);
>  }
>  
> +/**
> + * spi_nor_disable_block_protection() - Disable the write block protection
> + * during power-up.
> + * @nor:                pointer to a 'struct spi_nor'
> + *
> + * Some spi-nor flashes are write protected by default after a power-on reset
> + * cycle, in order to avoid inadvertend writes during power-up. Backward
> + * compatibility imposes to disable the write block protection at power-up
> + * by default.
> + *
> + * Return: 0 on success, -errno otherwise.
> + */
> +static int spi_nor_disable_block_protection(struct spi_nor *nor)
> +{
> +	if (!nor->params.disable_block_protection)
> +		return 0;
> +
> +	/*
> +	 * In case of the legacy quad enable requirements are set, if 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->params.quad_enable == spansion_quad_enable)
> +		nor->params.disable_block_protection =
> +			spi_nor_spansion_clear_sr_bp;

Hm, doesn't look right to adjust the function pointer just before
calling it. Can't we move that logic earlier (when doing the
default/manufacturer specific init)? Also, as I said in one of my
previous emails, I'd prefer to have this hook moved to
spi_nor_locking_ops and just have a flag to reflect when block
protection can be disabled.

> +
> +	return nor->params.disable_block_protection(nor);
> +}
> +
>  static int spi_nor_init(struct spi_nor *nor)
>  {
>  	int err;
>  
> -	if (nor->clear_sr_bp) {
> -		if (nor->quad_enable == spansion_quad_enable)
> -			nor->clear_sr_bp = spi_nor_spansion_clear_sr_bp;
> -
> -		err = nor->clear_sr_bp(nor);
> -		if (err) {
> -			dev_err(nor->dev,
> -				"fail to clear block protection bits\n");
> -			return err;
> -		}
> +	err = spi_nor_disable_block_protection(nor);
> +	if (err) {
> +		dev_err(nor->dev,
> +			"fail to unlock the flash at init (err = %d)\n", err);
> +		return err;
>  	}
>  
>  	err = spi_nor_quad_enable(nor);
> @@ -4635,7 +4660,7 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
>  	    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;
> +		nor->params.disable_block_protection = spi_nor_clear_sr_bp;
>  
>  	/* Parse the Serial Flash Discoverable Parameters table. */
>  	ret = spi_nor_init_params(nor);
> diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
> index 17787238f0e9..399ac34a529d 100644
> --- a/include/linux/mtd/spi-nor.h
> +++ b/include/linux/mtd/spi-nor.h
> @@ -480,6 +480,7 @@ struct spi_nor;
>   * @page_programs:	page program capabilities ordered by priority: the
>   *                      higher index in the array, the higher priority.
>   * @quad_enable:	enables SPI NOR quad mode.
> + * @disable_block_protection: disables block protection during power-up.
>   */
>  struct spi_nor_flash_parameter {
>  	u64				size;
> @@ -490,6 +491,7 @@ struct spi_nor_flash_parameter {
>  	struct spi_nor_pp_command	page_programs[SNOR_CMD_PP_MAX];
>  
>  	int (*quad_enable)(struct spi_nor *nor);
> +	int (*disable_block_protection)(struct spi_nor *nor);
>  };
>  
>  /**
> @@ -535,8 +537,6 @@ struct flash_info;
>   * @flash_unlock:	[FLASH-SPECIFIC] unlock a region of the SPI NOR
>   * @flash_is_locked:	[FLASH-SPECIFIC] check if a region of the SPI NOR is
>   *			completely locked
> - * @clear_sr_bp:	[FLASH-SPECIFIC] clears the Block Protection Bits from
> - *			the SPI NOR Status Register.
>   * @params:		[FLASH-SPECIFIC] SPI-NOR flash parameters and settings.
>   *                      The structure includes legacy flash parameters and
>   *                      settings that can be overwritten by the spi_nor_fixups
> @@ -578,7 +578,6 @@ struct spi_nor {
>  	int (*flash_lock)(struct spi_nor *nor, loff_t ofs, uint64_t len);
>  	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 (*clear_sr_bp)(struct spi_nor *nor);
>  	struct spi_nor_flash_parameter params;
>  
>  	void *priv;