powerpc/pseries: Perform proper max_bus_speed detection

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().

From: Lucas Kannebley Tavares <lucaskt@linux.vnet.ibm.com>
Signed-off-by: Kleber Sacilotto de Souza <klebers@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

5 files changed, 70 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
index 3f3f691be2e7..92386fc4e82a 100644
--- a/arch/powerpc/include/asm/machdep.h
+++ b/arch/powerpc/include/asm/machdep.h
@@ -29,6 +29,7 @@ struct rtc_time;
 struct file;
 struct pci_controller;
 struct kimage;
+struct pci_host_bridge;
 
 struct machdep_calls {
         char            *name;
@@ -108,6 +109,8 @@ 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 f325dc923409..d5811d8cc2c6 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c
@@ -845,6 +845,14 @@ 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 0b580f413a9a..5f93856cdf47 100644
--- a/arch/powerpc/platforms/pseries/pci.c
+++ b/arch/powerpc/platforms/pseries/pci.c
@@ -108,3 +108,56 @@ 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 = of_get_next_parent(pdn)) {
+                pcie_link_speed_stats = (const uint32_t *) of_get_property(pdn,
+                        "ibm,pcie-link-speed-stats", NULL);
+                if (pcie_link_speed_stats)
+                        break;
+        }
+
+        of_node_put(pdn);
+
+        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 8af71e4cc17f..c2a3a258001c 100644
--- a/arch/powerpc/platforms/pseries/pseries.h
+++ b/arch/powerpc/platforms/pseries/pseries.h
@@ -63,4 +63,8 @@ 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 ac932a9eb440..c11c8238797c 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) {