[v2 4/4] sata: imx: add ahci sata support on imx platforms

[Shawn Guo]

On Mon, Jul 01, 2013 at 06:36:11AM -0700, Tejun Heo wrote:
> On Mon, Jul 01, 2013 at 06:02:55PM +0800, Richard Zhu wrote:
> > imx6q contains one Synopsys AHCI SATA controller,
> > But it can't shares ahci_platform driver with other
> > controllers.
> > Because there are some misalignments of the bits
> > definitions of the HBA registers and the Vendor
> > Specific registers
> >  - CAP_SSS(bit20) of the HOST_CAP is writable, default
> >  value is '0', should be configured to be '1'
> >  - bit0 (only one AHCI SATA port on imx6q) of the
> >  HOST_PORTS_IMPL should be set to be '1'.(default 0)
> >  - One Vendor Specific register HOST_TIMER1MS(offset:0xe0)
> >  should be configured regarding to the frequency of AHB
> >  bus clock.
> 
> If these are the only differences, can't you make ahci_platform deal
> with different variants?  That's how we deal with subtly different
> variants of about the same controllers.

There are more:

 - There is an additional phy clock to manage
 - There are some i.MX SoC integration level registers to set up

I prefer to that we reuse the generic ahci_platform stuff, and handle
the differences in a sata_imx.c via pdata->init() interface.

Shawn