[U-Boot] [linux-sunxi] Re: [PATCH v2 3/3] ahci: provide sunxi SATA driver using AHCI platform framework

[Rob Herring]

On Thu, Feb 20, 2014 at 10:06 AM, Ian Campbell <ijc at hellion.org.uk> wrote:
> On Thu, 2014-02-20 at 09:24 -0600, Rob Herring wrote:
>> > +#define AHCI_PHYCS0R 0x00c0
>> > +#define AHCI_PHYCS1R 0x00c4
>> > +#define AHCI_PHYCS2R 0x00c8
> [...]
>> > +#define AHCI_RWCR 0x00fc
>
>> These registers are not sunxi specific, but part of a certain vendor's
>> IP found in several SOCs. I can't tell you who, but it shouldn't be
>> too hard to figure out.
>
> Actually, only the 4 above are used here and if I'm guessing which
> certain vendor you mean correctly then the code for those has these in
> its register map as reserved and doesn't touch them (this is true in
> both of the similar drivers I looked at).
>
> The rest of the registers in that list did look a lot the DW part
> (judging from the existing u-boot drivers) though.

There may be others that do this setup in firmware.

>> > +#define BIT(x) (1<<x)
>> > +static u32 sunxi_getbits(u8 *reg, u8 mask, u8 shift)
>> > +{
>> > +       return (readl(reg) >> shift) & mask;
>> > +}
>> > +
>> > +static int sunxi_ahci_phy_init(u32 base)
>> > +{
>> [...magic...]
>> > +
>>
>> I would guess this code or something very similar already exists in u-boot.
>
> I've had a look in the most obvious files in drivers/block/ and I don't
> see anything. Perhaps I should look harder.
>
> FWIW I also couldn't find anything similar in linux/drivers/ata.

I thought iMX needed something like this, but it doesn't look like it
now. Perhaps they figured out the bootrom is doing all this and it is
not really necessary to redo.

I don't really have any concrete suggestions here. I'm just
highlighting potential duplication. We already have 2 AHCI drivers in
u-boot. I think dwc_ahsata.c is the cleaner implementation, but ahci.c
is probably more well tested now. The Chromium folks have done various
fixes as has Calxeda. I think dwc_ahsata.c is only used for i.MX and
SATA is not the primary storage interface for most i.MX designs.

Rob