[PATCH v2] arm64: dts: marvell: armada-37xx: Remap IO space to bus address 0x0

[Pali Rohár]

Legacy and old PCI I/O based cards do not support 32-bit I/O addressing.

Since commit 64f160e19e92 ("PCI: aardvark: Configure PCIe resources from
'ranges' DT property") kernel can set different PCIe address on CPU and
different on the bus for the one A37xx address mapping without any firmware
support in case the bus address does not conflict with other A37xx mapping.

So remap I/O space to the bus address 0x0 to enable support for old legacy
I/O port based cards which have hardcoded I/O ports in low address space.

Note that DDR on A37xx is mapped to bus address 0x0. And mapping of I/O
space can be set to address 0x0 too because MEM space and I/O space are
separate and so do not conflict.

Remapping IO space on Turris Mox to different address is not possible to
due bootloader bug.

Signed-off-by: Pali Rohár <pali at kernel.org>
Reported-by: Arnd Bergmann <arnd at arndb.de>
Fixes: 76f6386b25cc ("arm64: dts: marvell: Add Aardvark PCIe support for Armada 3700")
Cc: stable at vger.kernel.org # 64f160e19e92 ("PCI: aardvark: Configure PCIe resources from 'ranges' DT property")
Cc: stable at vger.kernel.org # 514ef1e62d65 ("arm64: dts: marvell: armada-37xx: Extend PCIe MEM space")
Cc: stable at vger.kernel.org # ???????????? ("arm64: dts: marvell: armada-37xx: Increase PCIe IO size from 64 KiB to 1 MiB")

---
Changes in v2:
* Do not remap IO space on Turris Mox
---
 arch/arm64/boot/dts/marvell/armada-3720-turris-mox.dts | 7 ++++++-
 arch/arm64/boot/dts/marvell/armada-37xx.dtsi           | 2 +-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/boot/dts/marvell/armada-3720-turris-mox.dts b/arch/arm64/boot/dts/marvell/armada-3720-turris-mox.dts
index 6581092c2c90..2838e3f65ada 100644
--- a/arch/arm64/boot/dts/marvell/armada-3720-turris-mox.dts
+++ b/arch/arm64/boot/dts/marvell/armada-3720-turris-mox.dts
@@ -150,17 +150,22 @@
 	slot-power-limit = <10000>;
 	/*
 	 * U-Boot port for Turris Mox has a bug which always expects that "ranges" DT property
 	 * contains exactly 2 ranges with 3 (child) address cells, 2 (parent) address cells and
-	 * 2 size cells and also expects that the second range starts at 16 MB offset. If these
+	 * 2 size cells and also expects that the second range starts at 16 MB offset. Also it
+	 * expects that first range uses same address for PCI (child) and CPU (parent) cells (so
+	 * no remapping) and that this address is the lowest from all specified ranges. If these
 	 * conditions are not met then U-Boot crashes during loading kernel DTB file. PCIe address
 	 * space is 128 MB long, so the best split between MEM and IO is to use fixed 16 MB window
 	 * for IO and the rest 112 MB (64+32+16) for MEM. Controller supports 32-bit IO mapping.
 	 * This bug is not present in U-Boot ports for other Armada 3700 devices and is fixed in
 	 * U-Boot version 2021.07. See relevant U-Boot commits (the last one contains fix):
 	 * https://source.denx.de/u-boot/u-boot/-/commit/cb2ddb291ee6fcbddd6d8f4ff49089dfe580f5d7
 	 * https://source.denx.de/u-boot/u-boot/-/commit/c64ac3b3185aeb3846297ad7391fc6df8ecd73bf
 	 * https://source.denx.de/u-boot/u-boot/-/commit/4a82fca8e330157081fc132a591ebd99ba02ee33
+	 * Bug related to requirement of same child and parent addresses for first range is fixed
+	 * in U-Boot version 2022.04 by following commit:
+	 * https://source.denx.de/u-boot/u-boot/-/commit/1fd54253bca7d43d046bba4853fe5fafd034bc17
 	 */
 	#address-cells = <3>;
 	#size-cells = <2>;
 	ranges = <0x81000000 0 0xe8000000   0 0xe8000000   0 0x01000000   /* Port 0 IO */
diff --git a/arch/arm64/boot/dts/marvell/armada-37xx.dtsi b/arch/arm64/boot/dts/marvell/armada-37xx.dtsi
index 549c3f7c5b27..a099b7787429 100644
--- a/arch/arm64/boot/dts/marvell/armada-37xx.dtsi
+++ b/arch/arm64/boot/dts/marvell/armada-37xx.dtsi
@@ -514,9 +514,9 @@
 			 * IO at the end and the remaining seven windows
 			 * (totaling 127 MiB) for MEM.
 			 */
 			ranges = <0x82000000 0 0xe8000000   0 0xe8000000   0 0x07f00000   /* Port 0 MEM */
-				  0x81000000 0 0xeff00000   0 0xeff00000   0 0x00100000>; /* Port 0 IO*/
+				  0x81000000 0 0x00000000   0 0xeff00000   0 0x00100000>; /* Port 0 IO */
 			interrupt-map-mask = <0 0 0 7>;
 			interrupt-map = <0 0 0 1 &pcie_intc 0>,
 					<0 0 0 2 &pcie_intc 1>,
 					<0 0 0 3 &pcie_intc 2>,
-- 
2.20.1