From: Lucas Kannebley Tavares <redacted>

On pseries machines the detection for max_bus_speed should be done
through an OpenFirmware property. This patch adds a function to perform
this detection and a hook to perform dynamic adding of the function only for
pseries. This is done by overwriting the weak
pcibios_root_bridge_prepare function which is called by pci_create_root_bus().

Signed-off-by: Lucas Kannebley Tavares <redacted>
---
 arch/powerpc/include/asm/machdep.h       |  2 ++
 arch/powerpc/kernel/pci-common.c         |  8 +++++
 arch/powerpc/platforms/pseries/pci.c     | 51 ++++++++++++++++++++++++++++++++
 arch/powerpc/platforms/pseries/pseries.h |  4 +++
 arch/powerpc/platforms/pseries/setup.c   |  2 ++
 5 files changed, 67 insertions(+)

diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
index 3d6b410..8f558bf 100644
--- a/arch/powerpc/include/asm/machdep.h
+++ b/arch/powerpc/include/asm/machdep.h

@@ -107,6 +107,8 @@ struct machdep_calls {
 	void		(*pcibios_fixup)(void);
 	int		(*pci_probe_mode)(struct pci_bus *);
 	void		(*pci_irq_fixup)(struct pci_dev *dev);
+	int		(*pcibios_root_bridge_prepare)(struct pci_host_bridge
+				*bridge);
 
 	/* To setup PHBs when using automatic OF platform driver for PCI */
 	int		(*pci_setup_phb)(struct pci_controller *host);

diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index fa12ae4..80986cf 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c

@@ -844,6 +844,14 @@ int pci_proc_domain(struct pci_bus *bus)
 	return 1;
 }
 
+int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge)
+{
+	if (ppc_md.pcibios_root_bridge_prepare)
+		return ppc_md.pcibios_root_bridge_prepare(bridge);
+
+	return 0;
+}
+
 /* This header fixup will do the resource fixup for all devices as they are
  * probed, but not for bridge ranges
  */

diff --git a/arch/powerpc/platforms/pseries/pci.c b/arch/powerpc/platforms/pseries/pci.c
index 0b580f4..7f9c956 100644
--- a/arch/powerpc/platforms/pseries/pci.c
+++ b/arch/powerpc/platforms/pseries/pci.c

@@ -108,3 +108,54 @@ static void fixup_winbond_82c105(struct pci_dev* dev)
 }
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_WINBOND, PCI_DEVICE_ID_WINBOND_82C105,
 			 fixup_winbond_82c105);
+
+int pseries_root_bridge_prepare(struct pci_host_bridge *bridge)
+{
+	struct device_node *dn, *pdn;
+	struct pci_bus *bus;
+	const uint32_t *pcie_link_speed_stats;
+
+	bus = bridge->bus;
+
+	dn = pcibios_get_phb_of_node(bus);
+	if (!dn)
+		return 0;
+
+	for (pdn = dn; pdn != NULL; pdn = pdn->parent) {
+		pcie_link_speed_stats = (const uint32_t *) of_get_property(dn,
+			"ibm,pcie-link-speed-stats", NULL);
+		if (pcie_link_speed_stats)
+			break;
+	}