PCI: iproc: Improve link detection logic

Improve the link detection logic by explicitly querying the link status
register to ensure link is active.

Also force class to PCI_CLASS_BRIDGE_PCI (0x0604) through the host
configuration space register.

Signed-off-by: Ray Jui <rjui@broadcom.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Anup Patel <anup.patel@broadcom.com>
Reviewed-by: Scott Branden <sbranden@broadcom.com>

1 files changed, 23 insertions, 6 deletions

diff --git a/drivers/pci/host/pcie-iproc.c b/drivers/pci/host/pcie-iproc.c
index 80e0541548a1..62e80855aed1 100644
--- a/drivers/pci/host/pcie-iproc.c
+++ b/drivers/pci/host/pcie-iproc.c
@@ -60,6 +60,12 @@
 #define SYS_RC_INTX_EN               0x330
 #define SYS_RC_INTX_MASK             0xf
 
+#define PCIE_LINK_STATUS_OFFSET      0xf0c
+#define PCIE_PHYLINKUP_SHIFT         3
+#define PCIE_PHYLINKUP               BIT(PCIE_PHYLINKUP_SHIFT)
+#define PCIE_DL_ACTIVE_SHIFT         2
+#define PCIE_DL_ACTIVE               BIT(PCIE_DL_ACTIVE_SHIFT)
+
 static inline struct iproc_pcie *iproc_data(struct pci_bus *bus)
 {
         struct iproc_pcie *pcie;
@@ -138,9 +144,15 @@ static void iproc_pcie_reset(struct iproc_pcie *pcie)
 static int iproc_pcie_check_link(struct iproc_pcie *pcie, struct pci_bus *bus)
 {
         u8 hdr_type;
-        u32 link_ctrl;
+        u32 link_ctrl, class, val;
         u16 pos, link_status;
-        int link_is_active = 0;
+        bool link_is_active = false;
+
+        val = readl(pcie->base + PCIE_LINK_STATUS_OFFSET);
+        if (!(val & PCIE_PHYLINKUP) || !(val & PCIE_DL_ACTIVE)) {
+                dev_err(pcie->dev, "PHY or data link is INACTIVE!\n");
+                return -ENODEV;
+        }
 
         /* make sure we are not in EP mode */
         pci_bus_read_config_byte(bus, 0, PCI_HEADER_TYPE, &hdr_type);
@@ -150,14 +162,19 @@ static int iproc_pcie_check_link(struct iproc_pcie *pcie, struct pci_bus *bus)
         }
 
         /* force class to PCI_CLASS_BRIDGE_PCI (0x0604) */
-        pci_bus_write_config_word(bus, 0, PCI_CLASS_DEVICE,
-                                  PCI_CLASS_BRIDGE_PCI);
+#define PCI_BRIDGE_CTRL_REG_OFFSET 0x43c
+#define PCI_CLASS_BRIDGE_MASK      0xffff00
+#define PCI_CLASS_BRIDGE_SHIFT     8
+        pci_bus_read_config_dword(bus, 0, PCI_BRIDGE_CTRL_REG_OFFSET, &class);
+        class &= ~PCI_CLASS_BRIDGE_MASK;
+        class |= (PCI_CLASS_BRIDGE_PCI << PCI_CLASS_BRIDGE_SHIFT);
+        pci_bus_write_config_dword(bus, 0, PCI_BRIDGE_CTRL_REG_OFFSET, class);
 
         /* check link status to see if link is active */
         pos = pci_bus_find_capability(bus, 0, PCI_CAP_ID_EXP);
         pci_bus_read_config_word(bus, 0, pos + PCI_EXP_LNKSTA, &link_status);
         if (link_status & PCI_EXP_LNKSTA_NLW)
-                link_is_active = 1;
+                link_is_active = true;
 
         if (!link_is_active) {
                 /* try GEN 1 link speed */
@@ -181,7 +198,7 @@ static int iproc_pcie_check_link(struct iproc_pcie *pcie, struct pci_bus *bus)
                         pci_bus_read_config_word(bus, 0, pos + PCI_EXP_LNKSTA,
                                                  &link_status);
                         if (link_status & PCI_EXP_LNKSTA_NLW)
-                                link_is_active = 1;
+                                link_is_active = true;
                 }
         }