[U-Boot] [PATCH v6 15/20] tegra: fdt: Add function to return peripheral/clock ID

[Stephen Warren]

Simon Glass wrote at Tuesday, February 28, 2012 10:46 AM:
> On Mon, Feb 27, 2012 at 3:41 PM, Stephen Warren <swarren at nvidia.com> wrote:
> > On 02/27/2012 01:52 PM, Simon Glass wrote:
> >> A common requirement is to find the clock ID for a peripheral. This is the
> >> second cell of the 'clocks' property (the first being the phandle itself).
> >
> >> +int clock_decode_periph_id(const void *blob, int node)
> >
> >> +     valid = clock_periph_id_isvalid(id);
> >
> > clock_periph_id_isvalid() is not the correct function to use here; the
> > code should be checking for invalid IDs in the CAR binding, not invalid
> > IDs in the HW periph ID definition. They're different.
> >
> > Just to be explicit, the function you need here would be:
> >
> > int clkid_to_periphid(int clkid)
> > {
> >    if (clk_id > 95)
> >        return -1;
> >    switch (clk_id) {
> >    case 1:
> >    case 2:
> >    case 7:
> >    case 10:
> >    case 20:
> >    case 30:
> >    case 35:
> >    case 49:
> >    case 56:
> >    case 74:
> >    case 77:
> >    case 78:
> >    case 79:
> >    case 80:
> >    case 81:
> >    case 82:
> >    case 83:
> >    case 91:
> >    case 95:
> >        return -1;
> >    default:
> >        return clkid;
> >    }
> > }
> 
> Ick.
> 
> Why is 7 in there,

7 affects both the UART2 and VFIR clocks/blocks.

> and did you miss 76?

No, that's the undocumented "la" clock.

> Also U-Boot only goes up to 88
> at present so should I change the first test to match?

No, clocks 89, 90, 92, 93, and 94 are defined in the binding, which
matches the CLK_OUT_ENB registers in the Tegra CAR HW (albeit not the
CLK_RST registers, since there are some differences between the two).

-- 
nvpublic