On Thu, Nov 17, 2011 at 12:57:38PM -0600, Timur Tabi wrote:
> The Freescale P1022 has a unique pin muxing "feature" where the DIU video
> controller's video signals are muxed with 24 of the local bus address signals.
> When the DIU is enabled, the bulk of the local bus is disabled, preventing
> access to memory-mapped devices like NOR flash and the pixis FPGA.
>
> In this situation, the pixis supports "indirect mode", which allows access
> to the pixis itself by reading/writing addresses on specific local bus
> chip selects. CS0 is used to select which pixis register to access, and
> CS1 is used to read/write the value.
>
> To support this, we introduce another board-control child node of the
> localbus node that contains a 'reg' property for CS0 and CS1. This will
> produce the correct physical addresses for CS0 and CS1.
>
> Signed-off-by: Timur Tabi <ti...@freescale.com>
> ---
> arch/powerpc/boot/dts/p1022ds.dts | 14 ++++++++++++++
> 1 files changed, 14 insertions(+), 0 deletions(-)
>
> diff --git a/arch/powerpc/boot/dts/p1022ds.dts
> b/arch/powerpc/boot/dts/p1022ds.dts
> index 24a73e9..3e85d8c 100644
> --- a/arch/powerpc/boot/dts/p1022ds.dts
> +++ b/arch/powerpc/boot/dts/p1022ds.dts
> @@ -24,6 +24,20 @@
> 0x2 0x0 0xf 0xffa00000 0x00040000
> 0x3 0x0 0xf 0xffdf0000 0x00008000>;
>
> + /*
> + * This node is used to access the pixis via "indirect" mode,
> + * which is done by writing the pixis register index to chip
> + * select 0 and the value to/from chip select 1. Indirect
> + * mode is the only way to access the pixis when DIU video
> + * is enabled. Note that this assumes that the first column
> + * of the 'ranges' property above is the chip select number.
> + */
> + board-control@0,0 {
> + compatible = "fsl,p1022ds-indirect-pixis";
> + reg = <0x0 0x0 1 /* CS0 */
> + 0x1 0x0 1>; /* CS1 */
> + };
> +
> nor@0,0 {
> #address-cells = <1>;
> #size-cells = <1>;
U-Boot should mark some of these devices as disabled, based on whether
indirect mode is enabled on boot. If you're not going to do that, at
least remove simple-bus from the compatible list.
Something like this is probably the best way to describe it:
localbus {
compatible = "...", "fsl,elbc", "simple-bus";
ranges = <...>;
#address-cells = <2>;
#size-cells = <2>;
mux {
compatible = "fsl,p1022ds-localbus-mux"; // no simple-bus
fsl,localbus-mux-mode = "indirect"; // inital state on boot
ranges;
#address-cells = <2>;
#size-cells = <2>;
board-control@0,0 {
compatible = "fsl,p1022ds-indirect-pixis";
reg = <0 0 1
1 0 1>;
fsl,localbus-mux-avail = "indirect";
};
flash@0,0 {
...
fsl,localbus-mux-avail = "direct";
};
...
};
};
Or encode the mode as part of reg, as I suggested for someone else here:
http://lists.ozlabs.org/pipermail/devicetree-discuss/2011-November/009378.html
-Scott
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