Re: [PATCH v10 5/7] i2c: fsi: Add transfer implementation

[Eddie James]

On 06/25/2018 09:38 PM, Wolfram Sang wrote:
> On Wed, Jun 13, 2018 at 02:36:17PM -0500, Eddie James wrote:
> > Execute I2C transfers from the FSI-attached I2C master. Use polling
> > instead of interrupts as we have no hardware IRQ over FSI.
> >
> > Signed-off-by: Eddie James <eajames@xxxxxxxxxxxxxxxxxx>
> > ---
> >   drivers/i2c/busses/i2c-fsi.c | 195 ++++++++++++++++++++++++++++++++++++++++++-
> >   1 file changed, 193 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
> > index 4611a0b..8c0a6cb 100644
> > --- a/drivers/i2c/busses/i2c-fsi.c
> > +++ b/drivers/i2c/busses/i2c-fsi.c
> > @@ -155,6 +155,7 @@ struct fsi_i2c_port {
> >   	struct i2c_adapter	adapter;
> >   	struct fsi_i2c_master	*master;
> >   	u16			port;
> > +	u16			xfrd;
> >   };
> >   
> >   static int fsi_i2c_read_reg(struct fsi_device *fsi, unsigned int reg,
> > @@ -230,6 +231,99 @@ static int fsi_i2c_set_port(struct fsi_i2c_port *port)
> >   	return fsi_i2c_write_reg(fsi, I2C_FSI_RESET_ERR, &dummy);
> >   }
> >   
> > +static int fsi_i2c_start(struct fsi_i2c_port *port, struct i2c_msg *msg,
> > +			 bool stop)
> > +{
> > +	struct fsi_i2c_master *i2c = port->master;
> > +	u32 cmd = I2C_CMD_WITH_START | I2C_CMD_WITH_ADDR;
> > +
> > +	port->xfrd = 0;
> > +
> > +	if (msg->flags & I2C_M_RD)
> > +		cmd |= I2C_CMD_READ;
> Since you support MANGLING, I'd think you can easily support
> I2C_M_REV_DIR_ADDR here, too?

Hm, I don't really understand the purpose of that flag. From the docs:

This toggles the Rd/Wr flag. That is, if you want to do a write, but
ÂÂÂ need to emit an Rd instead of a Wr, or vice versa, you set this
ÂÂÂ flag. For example:
S Addr Rd [A] Data [A] Data [A] ... [A] Data [A] P

I don't think our hardware supports this type of operation.

Thanks,
Eddie

>