DT law_trgt_if property defines Local Access Window Target Interface.

Local Access Window Target Interface is used for identifying individual
peripheral and mapping its memory to CPU. Interface id is defined by
hardware itself.

U-Boot uses law_trgt_if DT property in PCIe nodes for configuring memory
mapping of individual PCIe controllers.

Linux kernel fsl_pci.c driver currently does not touch Local Access Window
and expects that U-Boot configures it properly.

Add law_trgt_if property to PCIe DT nodes for P2020. This allows usage of
kernel P2020 PCIe DT nodes in U-Boot. And therefore allows to share P2020
DTS files between Linux kernel and U-Boot.

Signed-off-by: Pali Rohár <pali@kernel.org>
---
 arch/powerpc/boot/dts/fsl/p2020si-post.dtsi | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/powerpc/boot/dts/fsl/p2020si-post.dtsi b/arch/powerpc/boot/dts/fsl/p2020si-post.dtsi
index 884e01bcb243..6345629524fe 100644
--- a/arch/powerpc/boot/dts/fsl/p2020si-post.dtsi
+++ b/arch/powerpc/boot/dts/fsl/p2020si-post.dtsi
@@ -48,6 +48,7 @@
 	bus-range = <0 255>;
 	clock-frequency = <33333333>;
 	interrupts = <26 2 0 0>;
+	law_trgt_if = <2>;
 
 	pcie@0 {
 		reg = <0 0 0 0 0>;
@@ -76,6 +77,7 @@
 	bus-range = <0 255>;
 	clock-frequency = <33333333>;
 	interrupts = <25 2 0 0>;
+	law_trgt_if = <1>;
 
 	pcie@0 {
 		reg = <0 0 0 0 0>;
@@ -105,6 +107,7 @@
 	bus-range = <0 255>;
 	clock-frequency = <33333333>;
 	interrupts = <24 2 0 0>;
+	law_trgt_if = <0>;
 
 	pcie@0 {
 		reg = <0 0 0 0 0>;
-- 
2.20.1

On Wed, May 4, 2022 at 1:09 PM Pali Rohár <pali@kernel.org> wrote:
>
> DT law_trgt_if property defines Local Access Window Target Interface.

Documentation?

fsl,law-trgt-if would be the preferred form.

> Local Access Window Target Interface is used for identifying individual
> peripheral and mapping its memory to CPU. Interface id is defined by
> hardware itself.

Normally, we avoid instance indices like this, but if it is more than
just documentation convention maybe that's fine.

Rob

On Thursday 05 May 2022 10:40:09 Rob Herring wrote:
> On Wed, May 4, 2022 at 1:09 PM Pali Rohár <pali@kernel.org> wrote:
> >
> > DT law_trgt_if property defines Local Access Window Target Interface.
> 
> Documentation?

I was not able to find it :-( So the only documentation for me was the
source code and decoding how it works and how it is used.

> fsl,law-trgt-if would be the preferred form.
> 
> > Local Access Window Target Interface is used for identifying individual
> > peripheral and mapping its memory to CPU. Interface id is defined by
> > hardware itself.
> 
> Normally, we avoid instance indices like this, but if it is more than
> just documentation convention maybe that's fine.
> 
> Rob

It is id defined by HW. Software needs to know how to pair DT node with
address range defined in "ranges" to the correct HW PCIe controller.