PCI: Restore PCI Express capability registers after PM event

Restore PCI Express capability registers after PM event.
This includes maxumum MTU for PCI express and other vital data.

Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 50 insertions, 0 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 590f4e6f505d..a544997399b3 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -445,6 +445,51 @@ pci_power_t pci_choose_state(struct pci_dev *dev, pm_message_t state)
 
 EXPORT_SYMBOL(pci_choose_state);
 
+static int pci_save_pcie_state(struct pci_dev *dev)
+{
+        int pos, i = 0;
+        struct pci_cap_saved_state *save_state;
+        u16 *cap;
+
+        pos = pci_find_capability(dev, PCI_CAP_ID_EXP);
+        if (pos <= 0)
+                return 0;
+
+        save_state = kzalloc(sizeof(*save_state) + sizeof(u16) * 4, GFP_KERNEL);
+        if (!save_state) {
+                dev_err(&dev->dev, "Out of memory in pci_save_pcie_state\n");
+                return -ENOMEM;
+        }
+        cap = (u16 *)&save_state->data[0];
+
+        pci_read_config_word(dev, pos + PCI_EXP_DEVCTL, &cap[i++]);
+        pci_read_config_word(dev, pos + PCI_EXP_LNKCTL, &cap[i++]);
+        pci_read_config_word(dev, pos + PCI_EXP_SLTCTL, &cap[i++]);
+        pci_read_config_word(dev, pos + PCI_EXP_RTCTL, &cap[i++]);
+        pci_add_saved_cap(dev, save_state);
+        return 0;
+}
+
+static void pci_restore_pcie_state(struct pci_dev *dev)
+{
+        int i = 0, pos;
+        struct pci_cap_saved_state *save_state;
+        u16 *cap;
+
+        save_state = pci_find_saved_cap(dev, PCI_CAP_ID_EXP);
+        pos = pci_find_capability(dev, PCI_CAP_ID_EXP);
+        if (!save_state || pos <= 0)
+                return;
+        cap = (u16 *)&save_state->data[0];
+
+        pci_write_config_word(dev, pos + PCI_EXP_DEVCTL, cap[i++]);
+        pci_write_config_word(dev, pos + PCI_EXP_LNKCTL, cap[i++]);
+        pci_write_config_word(dev, pos + PCI_EXP_SLTCTL, cap[i++]);
+        pci_write_config_word(dev, pos + PCI_EXP_RTCTL, cap[i++]);
+        pci_remove_saved_cap(save_state);
+        kfree(save_state);
+}
+
 /**
  * pci_save_state - save the PCI configuration space of a device before suspending
  * @dev: - PCI device that we're dealing with
@@ -460,6 +505,8 @@ pci_save_state(struct pci_dev *dev)
                 return i;
         if ((i = pci_save_msix_state(dev)) != 0)
                 return i;
+        if ((i = pci_save_pcie_state(dev)) != 0)
+                return i;
         return 0;
 }
 
@@ -473,6 +520,9 @@ pci_restore_state(struct pci_dev *dev)
         int i;
         int val;
 
+        /* PCI Express register must be restored first */
+        pci_restore_pcie_state(dev);
+
         /*
          * The Base Address register should be programmed before the command
          * register(s)