linux-kernel - Re: [RFC PATCH 2/6] mtd: spi-nor: core: consolidate read op creation

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Message-ID: <20210324080425.c4ospw4p6w7lrjok@ti.com>
Date:   Wed, 24 Mar 2021 13:34:27 +0530
From:   Pratyush Yadav <p.yadav@...com>
To:     Michael Walle <michael@...le.cc>
CC:     Nishanth Menon <nm@...com>, Tero Kristo <kristo@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Tudor Ambarus <tudor.ambarus@...rochip.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Mark Brown <broonie@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-mtd@...ts.infradead.org>, <linux-spi@...r.kernel.org>,
        Lokesh Vutla <lokeshvutla@...com>
Subject: Re: [RFC PATCH 2/6] mtd: spi-nor: core: consolidate read op creation

On 24/03/21 12:17AM, Michael Walle wrote:
> Am 2021-03-11 20:12, schrieb Pratyush Yadav:
> > Currently the spi_mem_op to read from the flash is used in two places:
> > spi_nor_create_read_dirmap() and spi_nor_spimem_read_data(). In a later
> > commit this number will increase to three. Instead of repeating the same
> > code thrice, add a function that returns a template of the read op. The
> > callers can then fill in the details like address, data length, data
> > buffer location.
> > 
> > Signed-off-by: Pratyush Yadav <p.yadav@...com>
> > ---
> >  drivers/mtd/spi-nor/core.c | 62 ++++++++++++++++++++------------------
> >  1 file changed, 32 insertions(+), 30 deletions(-)
> > 
> > diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> > index 4a315cb1c4db..88888df009f0 100644
> > --- a/drivers/mtd/spi-nor/core.c
> > +++ b/drivers/mtd/spi-nor/core.c
> > @@ -183,6 +183,33 @@ static int spi_nor_controller_ops_erase(struct
> > spi_nor *nor, loff_t offs)
> >  	return nor->controller_ops->erase(nor, offs);
> >  }
> > 
> > +/**
> > + * spi_nor_spimem_get_read_op() - return a template for the spi_mem_op
> > used for
> > + *                                reading data from the flash via
> > spi-mem.
> > + * @nor:        pointer to 'struct spi_nor'
> > + *
> > + * Return: A template of the 'struct spi_mem_op' for used for reading
> > data from
> > + * the flash. The caller is expected to fill in the address, data
> > length, and
> > + * the data buffer.
> > + */
> > +static struct spi_mem_op spi_nor_spimem_get_read_op(struct spi_nor
> > *nor)
> > +{
> > +	struct spi_mem_op op =
> > +		SPI_MEM_OP(SPI_MEM_OP_CMD(nor->read_opcode, 0),
> > +			   SPI_MEM_OP_ADDR(nor->addr_width, 0, 0),
> > +			   SPI_MEM_OP_DUMMY(nor->read_dummy, 0),
> > +			   SPI_MEM_OP_DATA_IN(1, NULL, 0));
> > +
> > +	spi_nor_spimem_setup_op(nor, &op, nor->read_proto);
> > +
> > +	/* convert the dummy cycles to the number of bytes */
> > +	op.dummy.nbytes = (nor->read_dummy * op.dummy.buswidth) / 8;
> > +	if (spi_nor_protocol_is_dtr(nor->read_proto))
> > +		op.dummy.nbytes *= 2;
> > +
> > +	return op;
> > +}
> > +
> >  /**
> >   * spi_nor_spimem_read_data() - read data from flash's memory region
> > via
> >   *                              spi-mem
> > @@ -196,21 +223,14 @@ static int spi_nor_controller_ops_erase(struct
> > spi_nor *nor, loff_t offs)
> >  static ssize_t spi_nor_spimem_read_data(struct spi_nor *nor, loff_t
> > from,
> >  					size_t len, u8 *buf)
> >  {
> > -	struct spi_mem_op op =
> > -		SPI_MEM_OP(SPI_MEM_OP_CMD(nor->read_opcode, 0),
> > -			   SPI_MEM_OP_ADDR(nor->addr_width, from, 0),
> > -			   SPI_MEM_OP_DUMMY(nor->read_dummy, 0),
> > -			   SPI_MEM_OP_DATA_IN(len, buf, 0));
> > +	struct spi_mem_op op = spi_nor_spimem_get_read_op(nor);
> >  	bool usebouncebuf;
> >  	ssize_t nbytes;
> >  	int error;
> > 
> > -	spi_nor_spimem_setup_op(nor, &op, nor->read_proto);
> > -
> > -	/* convert the dummy cycles to the number of bytes */
> > -	op.dummy.nbytes = (nor->read_dummy * op.dummy.buswidth) / 8;
> > -	if (spi_nor_protocol_is_dtr(nor->read_proto))
> > -		op.dummy.nbytes *= 2;
> > +	op.addr.val = from;
> > +	op.data.nbytes = len;
> > +	op.data.buf.in = buf;
> > 
> >  	usebouncebuf = spi_nor_spimem_bounce(nor, &op);
> > 
> > @@ -3581,28 +3601,10 @@ EXPORT_SYMBOL_GPL(spi_nor_scan);
> >  static int spi_nor_create_read_dirmap(struct spi_nor *nor)
> >  {
> >  	struct spi_mem_dirmap_info info = {
> > -		.op_tmpl = SPI_MEM_OP(SPI_MEM_OP_CMD(nor->read_opcode, 0),
> > -				      SPI_MEM_OP_ADDR(nor->addr_width, 0, 0),
> > -				      SPI_MEM_OP_DUMMY(nor->read_dummy, 0),
> > -				      SPI_MEM_OP_DATA_IN(0, NULL, 0)),
> > +		.op_tmpl = spi_nor_spimem_get_read_op(nor),
> >  		.offset = 0,
> >  		.length = nor->mtd.size,
> >  	};
> > -	struct spi_mem_op *op = &info.op_tmpl;
> > -
> > -	spi_nor_spimem_setup_op(nor, op, nor->read_proto);
> > -
> > -	/* convert the dummy cycles to the number of bytes */
> > -	op->dummy.nbytes = (nor->read_dummy * op->dummy.buswidth) / 8;
> > -	if (spi_nor_protocol_is_dtr(nor->read_proto))
> > -		op->dummy.nbytes *= 2;
> > -
> > -	/*
> > -	 * Since spi_nor_spimem_setup_op() only sets buswidth when the number
> > -	 * of data bytes is non-zero, the data buswidth won't be set here. So,
> > -	 * do it explicitly.
> > -	 */
> > -	op->data.buswidth = spi_nor_get_protocol_data_nbits(nor->read_proto);
> 
> I guess this isn't needed anymore because spi_nor_spimem_get_read_op() uses
> a
> data length of 1, right?

Yes.

> 
> > 
> >  	nor->dirmap.rdesc = devm_spi_mem_dirmap_create(nor->dev, nor->spimem,
> >  						       &info);
> 
> -michael

-- 
Regards,
Pratyush Yadav
Texas Instruments Inc.