[PATCH 5.15 638/779] powerpc/pci: Prefer PCI domain assignment via DT linux,pci-domain and alias

[Greg Kroah-Hartman]

From: Pali Rohár <pali@xxxxxxxxxx>

[ Upstream commit 0fe1e96fef0a5c53b4c0d1500d356f3906000f81 ]

Other Linux architectures use DT property 'linux,pci-domain' for
specifying fixed PCI domain of PCI controller specified in Device-Tree.

And lot of Freescale powerpc boards have defined numbered pci alias in
Device-Tree for every PCIe controller which number specify preferred PCI
domain.

So prefer usage of DT property 'linux,pci-domain' (via function
of_get_pci_domain_nr()) and DT pci alias (via function
of_alias_get_id()) on powerpc architecture for assigning PCI domain to
PCI controller.

Fixes: 63a72284b159 ("powerpc/pci: Assign fixed PHB number based on device-tree properties")
Signed-off-by: Pali Rohár <pali@xxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220706102148.5060-2-pali@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 arch/powerpc/kernel/pci-common.c | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index c3573430919d..08eea633c380 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c
@@ -74,16 +74,30 @@ void set_pci_dma_ops(const struct dma_map_ops *dma_ops)
 static int get_phb_number(struct device_node *dn)
 {
 	int ret, phb_id = -1;
-	u32 prop_32;
 	u64 prop;
 
 	/*
 	 * Try fixed PHB numbering first, by checking archs and reading
-	 * the respective device-tree properties. Firstly, try powernv by
-	 * reading "ibm,opal-phbid", only present in OPAL environment.
+	 * the respective device-tree properties. Firstly, try reading
+	 * standard "linux,pci-domain", then try reading "ibm,opal-phbid"
+	 * (only present in powernv OPAL environment), then try device-tree
+	 * alias and as the last try to use lower bits of "reg" property.
 	 */
-	ret = of_property_read_u64(dn, "ibm,opal-phbid", &prop);
+	ret = of_get_pci_domain_nr(dn);
+	if (ret >= 0) {
+		prop = ret;
+		ret = 0;
+	}
+	if (ret)
+		ret = of_property_read_u64(dn, "ibm,opal-phbid", &prop);
+	if (ret)
+		ret = of_alias_get_id(dn, "pci");
+	if (ret >= 0) {
+		prop = ret;
+		ret = 0;
+	}
 	if (ret) {
+		u32 prop_32;
 		ret = of_property_read_u32_index(dn, "reg", 1, &prop_32);
 		prop = prop_32;
 	}
@@ -95,10 +109,7 @@ static int get_phb_number(struct device_node *dn)
 	if ((phb_id >= 0) && !test_and_set_bit(phb_id, phb_bitmap))
 		return phb_id;
 
-	/*
-	 * If not pseries nor powernv, or if fixed PHB numbering tried to add
-	 * the same PHB number twice, then fallback to dynamic PHB numbering.
-	 */
+	/* If everything fails then fallback to dynamic PHB numbering. */
 	phb_id = find_first_zero_bit(phb_bitmap, MAX_PHBS);
 	BUG_ON(phb_id >= MAX_PHBS);
 	set_bit(phb_id, phb_bitmap);
-- 
2.35.1