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

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Message-ID: <69943a92-b44e-8c39-5c1d-dedc6829828e@microchip.com>
Date:   Tue, 19 Apr 2022 12:59:40 +0000
From:   <Tudor.Ambarus@...rochip.com>
To:     <michael@...le.cc>
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@...ineon.com>
Subject: Re: [PATCH v3 6/9] mtd: spi-nor: core: Add helpers to read/write any
 register

On 4/19/22 14:19, Michael Walle wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> 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

is spi_nor_read_any_reg a better name than spi_nor_read_reg?


> just executes an op, the write executes an op with a
> write enable before. All the behavior is determined by the
> 'op' argument.

it still avoids code duplication, doesn't it?

Thanks,
ta
> 
> 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);
>> +}
>> +
>>  /**
>>   * spi_nor_write_enable() - Set write enable latch with Write Enable
>> command.
>>   * @nor:     pointer to 'struct spi_nor'.
>> diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
>> index f952061d5c24..7c704475946d 100644
>> --- a/drivers/mtd/spi-nor/core.h
>> +++ b/drivers/mtd/spi-nor/core.h
>> @@ -554,6 +554,10 @@ ssize_t spi_nor_read_data(struct spi_nor *nor,
>> loff_t from, size_t len,
>>                         u8 *buf);
>>  ssize_t spi_nor_write_data(struct spi_nor *nor, loff_t to, size_t len,
>>                          const u8 *buf);
>> +int spi_nor_read_reg(struct spi_nor *nor, struct spi_mem_op *op,
>> +                  enum spi_nor_protocol proto);
>> +int spi_nor_write_reg(struct spi_nor *nor, struct spi_mem_op *op,
>> +                   enum spi_nor_protocol proto);
>>  int spi_nor_erase_sector(struct spi_nor *nor, u32 addr);
>>
>>  int spi_nor_otp_read_secr(struct spi_nor *nor, loff_t addr, size_t
>> len, u8 *buf);
> 
> -- 
> -michael