Re: [PATCH 4/5] mtd: spi-nor: Move clear_sr_bp() to 'struct spi_nor_flash_parameter'

[Tudor.Ambarus]

On 08/25/2019 04:09 PM, Boris Brezillon wrote:
> On Fri, 23 Aug 2019 15:53:41 +0000
> <Tudor.Ambarus@xxxxxxxxxxxxx> wrote:
> 
>> From: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>
>>
>> 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@xxxxxxxxxxxxx>
>> ---
>>  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

No, we can't move it earlier to ->default_init() because the pointer to
quad_enable() function can be modified later on, when parsing SFDP. This should
stay here, after the quad_enable() method is known, so after the
spi_nor_init_params() call.


> 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.

yes, I agree, will move.

> 
>> +
>> +	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;
> 
>