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Date:   Tue, 19 Apr 2022 13:19:41 +0200
From:   Michael Walle <michael@walle.cc>
To:     Tudor Ambarus <tudor.ambarus@microchip.com>
Cc:     p.yadav@ti.com, miquel.raynal@bootlin.com, richard@nod.at,
        vigneshr@ti.com, linux-mtd@lists.infradead.org,
        linux-kernel@vger.kernel.org, nicolas.ferre@microchip.com,
        Takahiro Kuwano <Takahiro.Kuwano@infineon.com>
Subject: Re: [PATCH v3 6/9] mtd: spi-nor: core: Add helpers to read/write any
 register
In-Reply-To: <20220411091033.98754-7-tudor.ambarus@microchip.com>
References: <20220411091033.98754-1-tudor.ambarus@microchip.com>
 <20220411091033.98754-7-tudor.ambarus@microchip.com>
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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@microchip.com>
> Tested-by: Takahiro Kuwano <Takahiro.Kuwano@infineon.com>
> Reviewed-by: Pratyush Yadav <p.yadav@ti.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@walle.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