linux-kernel - Re: [PATCH v3 6/9] mtd: spi-nor: core: Add helpers to read/write any register

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Date:   Tue, 19 Apr 2022 13:46:42 +0200
From:   Michael Walle <michael@...le.cc>
To:     Tudor Ambarus <tudor.ambarus@...rochip.com>
Cc:     p.yadav@...com, miquel.raynal@...tlin.com, richard@....at,
        vigneshr@...com, linux-mtd@...ts.infradead.org,
        linux-kernel@...r.kernel.org, nicolas.ferre@...rochip.com,
        Takahiro Kuwano <Takahiro.Kuwano@...ineon.com>
Subject: Re: [PATCH v3 6/9] mtd: spi-nor: core: Add helpers to read/write any
 register

Am 2022-04-19 13:19, schrieb Michael Walle:
> Am 2022-04-11 11:10, schrieb Tudor Ambarus:
>> There are manufacturers that use registers indexed by address. Some of
>> them support "read/write any register" opcodes. Provide core methods 
>> that
>> can be used by all manufacturers. SPI NOR controller ops are 
>> intentionally
>> not supported as we intend to move all the SPI NOR controller drivers
>> under the SPI subsystem.
>> 
>> Signed-off-by: Tudor Ambarus <tudor.ambarus@...rochip.com>
>> Tested-by: Takahiro Kuwano <Takahiro.Kuwano@...ineon.com>
>> Reviewed-by: Pratyush Yadav <p.yadav@...com>
> 
> I still don't like it because the function doesn't do
> anything what the function name might suggest. The read
> just executes an op, the write executes an op with a
> write enable before. All the behavior is determined by the
> 'op' argument.
> 
> Anyway,
> Reviewed-by: Michael Walle <michael@...le.cc>
> 
>> ---
>> v3: no changes
>> 
>>  drivers/mtd/spi-nor/core.c | 41 
>> ++++++++++++++++++++++++++++++++++++++
>>  drivers/mtd/spi-nor/core.h |  4 ++++
>>  2 files changed, 45 insertions(+)
>> 
>> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
>> index 6165dc7bfd17..42794328d3b6 100644
>> --- a/drivers/mtd/spi-nor/core.c
>> +++ b/drivers/mtd/spi-nor/core.c
>> @@ -307,6 +307,47 @@ ssize_t spi_nor_write_data(struct spi_nor *nor,
>> loff_t to, size_t len,
>>  	return nor->controller_ops->write(nor, to, len, buf);
>>  }
>> 
>> +/**
>> + * spi_nor_read_reg() - read register to flash memory
>> + * @nor:        pointer to 'struct spi_nor'.
>> + * @op:		SPI memory operation. op->data.buf must be DMA-able.
>> + * @proto:	SPI protocol to use for the register operation.
>> + *
>> + * Return: zero on success, -errno otherwise
>> + */
>> +int spi_nor_read_reg(struct spi_nor *nor, struct spi_mem_op *op,
>> +		     enum spi_nor_protocol proto)
>> +{
>> +	if (!nor->spimem)
>> +		return -EOPNOTSUPP;
>> +
>> +	spi_nor_spimem_setup_op(nor, op, proto);
>> +	return spi_nor_spimem_exec_op(nor, op);
>> +}
>> +
>> +/**
>> + * spi_nor_write_reg() - write register to flash memory
>> + * @nor:        pointer to 'struct spi_nor'
>> + * @op:		SPI memory operation. op->data.buf must be DMA-able.
>> + * @proto:	SPI protocol to use for the register operation.
>> + *
>> + * Return: zero on success, -errno otherwise
>> + */
>> +int spi_nor_write_reg(struct spi_nor *nor, struct spi_mem_op *op,
>> +		      enum spi_nor_protocol proto)
>> +{
>> +	int ret;
>> +
>> +	if (!nor->spimem)
>> +		return -EOPNOTSUPP;
>> +
>> +	ret = spi_nor_write_enable(nor);
>> +	if (ret)
>> +		return ret;
>> +	spi_nor_spimem_setup_op(nor, op, proto);
>> +	return spi_nor_spimem_exec_op(nor, op);

After seeing your next two patches. Shouldn't the
spi_nor_wait_until_ready() call be here too?

-michael