[PATCHv4 1/2] ppc64: perform proper max_bus_speed detection

[lucaskt@linux.vnet.ibm.com]

From: Lucas Kannebley Tavares <lucaskt@linux.vnet.ibm.com>

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 <lucaskt@linux.vnet.ibm.com>
---
 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;
+	}
+
+	if (!pcie_link_speed_stats) {
+		pr_err("no ibm,pcie-link-speed-stats property\n");
+		return 0;
+	}
+
+	switch (pcie_link_speed_stats[0]) {
+	case 0x01:
+		bus->max_bus_speed = PCIE_SPEED_2_5GT;
+		break;
+	case 0x02:
+		bus->max_bus_speed = PCIE_SPEED_5_0GT;
+		break;
+	default:
+		bus->max_bus_speed = PCI_SPEED_UNKNOWN;
+		break;
+	}
+
+	switch (pcie_link_speed_stats[1]) {
+	case 0x01:
+		bus->cur_bus_speed = PCIE_SPEED_2_5GT;
+		break;
+	case 0x02:
+		bus->cur_bus_speed = PCIE_SPEED_5_0GT;
+		break;
+	default:
+		bus->cur_bus_speed = PCI_SPEED_UNKNOWN;
+		break;
+	}
+
+	return 0;
+}
diff --git a/arch/powerpc/platforms/pseries/pseries.h b/arch/powerpc/platforms/pseries/pseries.h
index 9a3dda0..b79393d 100644
--- a/arch/powerpc/platforms/pseries/pseries.h
+++ b/arch/powerpc/platforms/pseries/pseries.h
@@ -60,4 +60,8 @@ extern int dlpar_detach_node(struct device_node *);
 /* Snooze Delay, pseries_idle */
 DECLARE_PER_CPU(long, smt_snooze_delay);
 
+/* PCI root bridge prepare function override for pseries */
+struct pci_host_bridge;
+int pseries_root_bridge_prepare(struct pci_host_bridge *bridge);
+
 #endif /* _PSERIES_PSERIES_H */
diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index 8bcc9ca..bf34cc9 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -466,6 +466,8 @@ static void __init pSeries_setup_arch(void)
 	else
 		ppc_md.enable_pmcs = power4_enable_pmcs;
 
+	ppc_md.pcibios_root_bridge_prepare = pseries_root_bridge_prepare;
+
 	if (firmware_has_feature(FW_FEATURE_SET_MODE)) {
 		long rc;
 		if ((rc = pSeries_enable_reloc_on_exc()) != H_SUCCESS) {
-- 
1.8.1.4