linux-kernel - [PATCH 4.4 069/312] powerpc/pci/of: Parse unassigned resources

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Message-Id: <20200508123129.400872881@linuxfoundation.org>
Date:   Fri,  8 May 2020 14:31:00 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Alexey Kardashevskiy <aik@...abs.ru>,
        Michael Ellerman <mpe@...erman.id.au>,
        Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH 4.4 069/312] powerpc/pci/of: Parse unassigned resources

From: Alexey Kardashevskiy <aik@...abs.ru>

commit dead1c845dbe97e0061dae2017eaf3bd8f8f06ee upstream.

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@...abs.ru>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Cc: Guenter Roeck <linux@...ck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/powerpc/kernel/pci_of_scan.c |   12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

--- 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 de
 	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 de
 			continue;
 		}
 		res->flags = flags;
+		if (mark_unset)
+			res->flags |= IORESOURCE_UNSET;
 		res->name = pci_name(dev);
 		region.start = base;
 		region.end = base + size - 1;