From dead1c845dbe97e0061dae2017eaf3bd8f8f06ee Mon Sep 17 00:00:00 2001
From: Alexey Kardashevskiy <aik@ozlabs.ru>
Date: Wed, 26 Jun 2019 12:37:46 +1000
Subject: [PATCH] powerpc/pci/of: Parse unassigned resources

References: bsc#1065729
Patch-mainline: v5.3-rc1
Git-commit: dead1c845dbe97e0061dae2017eaf3bd8f8f06ee

The pseries platform uses the PCI_PROBE_DEVTREE method of PCI probing
which reads "assigned-addresses" of every PCI device and initializes
the device resources. However if the property is missing or zero sized,
then there is no fallback of any kind and the PCI resources remain
undiscovered, i.e. pdev->resource[] array remains empty.

This adds a fallback which parses the "reg" property in pretty much same
way except it marks resources as "unset" which later make Linux assign
those resources proper addresses.

This has an effect when:
1. a hypervisor failed to assign any resource for a device;
2. /chosen/linux,pci-probe-only=0 is in the DT so the system may try
assigning a resource.
Neither is likely to happen under PowerVM.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/kernel/pci_of_scan.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/pci_of_scan.c b/arch/powerpc/kernel/pci_of_scan.c
index 64ad92016b63..bd78f325a636 100644
--- a/arch/powerpc/kernel/pci_of_scan.c
+++ b/arch/powerpc/kernel/pci_of_scan.c
@@ -82,10 +82,16 @@ static void of_pci_parse_addrs(struct device_node *node, struct pci_dev *dev)
 	const __be32 *addrs;
 	u32 i;
 	int proplen;
+	bool mark_unset = false;
 
 	addrs = of_get_property(node, "assigned-addresses", &proplen);
-	if (!addrs)
-		return;
+	if (!addrs || !proplen) {
+		addrs = of_get_property(node, "reg", &proplen);
+		if (!addrs || !proplen)
+			return;
+		mark_unset = true;
+	}
+
 	pr_debug("    parse addresses (%d bytes) @ %p\n", proplen, addrs);
 	for (; proplen >= 20; proplen -= 20, addrs += 5) {
 		flags = pci_parse_of_flags(of_read_number(addrs, 1), 0);
@@ -110,6 +116,8 @@ static void of_pci_parse_addrs(struct device_node *node, struct pci_dev *dev)
 			continue;
 		}
 		res->flags = flags;
+		if (mark_unset)
+			res->flags |= IORESOURCE_UNSET;
 		res->name = pci_name(dev);
 		region.start = base;
 		region.end = base + size - 1;
-- 
2.26.2