[PATCH v8 01/28] spi: spi-mem: allow specifying whether an op is DTR or not

[Tom Rini]

On Mon, Apr 05, 2021 at 01:55:06PM +0530, Pratyush Yadav wrote:
> On 02/04/21 06:21PM, Sean Anderson wrote:
> > 
> > On 4/1/21 3:31 PM, Pratyush Yadav wrote:
> > > Each phase is given a separate 'dtr' field so mixed protocols like
> > > 4S-4D-4D can be supported.
> > > 
> > > Signed-off-by: Pratyush Yadav <p.yadav at ti.com>
> > > ---
> > >   drivers/spi/spi-mem.c | 3 +++
> > >   include/spi-mem.h     | 8 ++++++++
> > >   2 files changed, 11 insertions(+)
> > > 
> > > diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
> > > index c095ae9505..427f7c13c5 100644
> > > --- a/drivers/spi/spi-mem.c
> > > +++ b/drivers/spi/spi-mem.c
> > > @@ -164,6 +164,9 @@ bool spi_mem_default_supports_op(struct spi_slave *slave,
> > >   				   op->data.dir == SPI_MEM_DATA_OUT))
> > >   		return false;
> > > +	if (op->cmd.dtr || op->addr.dtr || op->dummy.dtr || op->data.dtr)
> > > +		return false;
> > > +
> > >   	return true;
> > >   }
> > >   EXPORT_SYMBOL_GPL(spi_mem_default_supports_op);
> > > diff --git a/include/spi-mem.h b/include/spi-mem.h
> > > index 8be3e2bf6b..9e6b044548 100644
> > > --- a/include/spi-mem.h
> > > +++ b/include/spi-mem.h
> > > @@ -71,6 +71,7 @@ enum spi_mem_data_dir {
> > >    * struct spi_mem_op - describes a SPI memory operation
> > >    * @cmd.buswidth: number of IO lines used to transmit the command
> > >    * @cmd.opcode: operation opcode
> > > + * @cmd.dtr: whether the command opcode should be sent in DTR mode or not
> > >    * @addr.nbytes: number of address bytes to send. Can be zero if the operation
> > >    *		 does not need to send an address
> > >    * @addr.buswidth: number of IO lines used to transmit the address cycles
> > > @@ -78,10 +79,13 @@ enum spi_mem_data_dir {
> > >    *	      Note that only @addr.nbytes are taken into account in this
> > >    *	      address value, so users should make sure the value fits in the
> > >    *	      assigned number of bytes.
> > > + * @addr.dtr: whether the address should be sent in DTR mode or not
> > >    * @dummy.nbytes: number of dummy bytes to send after an opcode or address. Can
> > >    *		  be zero if the operation does not require dummy bytes
> > >    * @dummy.buswidth: number of IO lanes used to transmit the dummy bytes
> > > + * @dummy.dtr: whether the dummy bytes should be sent in DTR mode or not
> > >    * @data.buswidth: number of IO lanes used to send/receive the data
> > > + * @data.dtr: whether the data should be sent in DTR mode or not
> > >    * @data.dir: direction of the transfer
> > >    * @data.buf.in: input buffer
> > >    * @data.buf.out: output buffer
> > > @@ -90,21 +94,25 @@ struct spi_mem_op {
> > >   	struct {
> > >   		u8 buswidth;
> > >   		u8 opcode;
> > > +		u8 dtr : 1;
> > >   	} cmd;
> > >   	struct {
> > >   		u8 nbytes;
> > >   		u8 buswidth;
> > > +		u8 dtr : 1;
> > >   		u64 val;
> > >   	} addr;
> > >   	struct {
> > >   		u8 nbytes;
> > >   		u8 buswidth;
> > > +		u8 dtr : 1;
> > >   	} dummy;
> > >   	struct {
> > >   		u8 buswidth;
> > > +		u8 dtr : 1;
> > >   		enum spi_mem_data_dir dir;
> > >   		unsigned int nbytes;
> > >   		/* buf.{in,out} must be DMA-able. */
> > > 
> > 
> > I know this is following the Linux code, but are bitfields kosher for
> > U-Boot? This is more of a general question than a specific critique of
> > this code.
> 
> I'm not sure. I did a quick grep and I do see some usages of bitfields 
> but I'm not sure if these just slipped in with ports from Linux or they 
> are "officially" allowed.

We try to be a friendly environment to people used to working on the
Linux kernel, so is there a reason we wouldn't allow bitfields?

-- 
Tom
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