PCI: only save/restore existent registers in the PCIe capability

PCIe 1.1 base neither requires the endpoint to implement the entire
PCIe capability structure nor specifies default values of registers
that are not implemented by the device. So we only save and restore
registers that must be implemented by different device types if the
device PCIe capability version is 1.

PCIe 1.1 Capability Structure Expansion ECN and PCIe 2.0 requires
all registers in the PCIe capability to be either implemented or
hardwired to 0. Their PCIe capability version is 2.

Signed-off-by: Yu Zhao <yu.zhao@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 56 insertions, 14 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 16fd0d4c3166..34bf0fdf5047 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -681,11 +681,34 @@ EXPORT_SYMBOL(pci_choose_state);
 
 #define PCI_EXP_SAVE_REGS       7
 
+#define pcie_cap_has_devctl(type, flags)        1
+#define pcie_cap_has_lnkctl(type, flags)                \
+                ((flags & PCI_EXP_FLAGS_VERS) > 1 ||    \
+                 (type == PCI_EXP_TYPE_ROOT_PORT ||     \
+                  type == PCI_EXP_TYPE_ENDPOINT ||      \
+                  type == PCI_EXP_TYPE_LEG_END))
+#define pcie_cap_has_sltctl(type, flags)                \
+                ((flags & PCI_EXP_FLAGS_VERS) > 1 ||    \
+                 ((type == PCI_EXP_TYPE_ROOT_PORT) ||   \
+                  (type == PCI_EXP_TYPE_DOWNSTREAM &&   \
+                   (flags & PCI_EXP_FLAGS_SLOT))))
+#define pcie_cap_has_rtctl(type, flags)                 \
+                ((flags & PCI_EXP_FLAGS_VERS) > 1 ||    \
+                 (type == PCI_EXP_TYPE_ROOT_PORT ||     \
+                  type == PCI_EXP_TYPE_RC_EC))
+#define pcie_cap_has_devctl2(type, flags)               \
+                ((flags & PCI_EXP_FLAGS_VERS) > 1)
+#define pcie_cap_has_lnkctl2(type, flags)               \
+                ((flags & PCI_EXP_FLAGS_VERS) > 1)
+#define pcie_cap_has_sltctl2(type, flags)               \
+                ((flags & PCI_EXP_FLAGS_VERS) > 1)
+
 static int pci_save_pcie_state(struct pci_dev *dev)
 {
         int pos, i = 0;
         struct pci_cap_saved_state *save_state;
         u16 *cap;
+        u16 flags;
 
         pos = pci_find_capability(dev, PCI_CAP_ID_EXP);
         if (pos <= 0)
@@ -698,13 +721,22 @@ static int pci_save_pcie_state(struct pci_dev *dev)
         }
         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_read_config_word(dev, pos + PCI_EXP_DEVCTL2, &cap[i++]);
-        pci_read_config_word(dev, pos + PCI_EXP_LNKCTL2, &cap[i++]);
-        pci_read_config_word(dev, pos + PCI_EXP_SLTCTL2, &cap[i++]);
+        pci_read_config_word(dev, pos + PCI_EXP_FLAGS, &flags);
+
+        if (pcie_cap_has_devctl(dev->pcie_type, flags))
+                pci_read_config_word(dev, pos + PCI_EXP_DEVCTL, &cap[i++]);
+        if (pcie_cap_has_lnkctl(dev->pcie_type, flags))
+                pci_read_config_word(dev, pos + PCI_EXP_LNKCTL, &cap[i++]);
+        if (pcie_cap_has_sltctl(dev->pcie_type, flags))
+                pci_read_config_word(dev, pos + PCI_EXP_SLTCTL, &cap[i++]);
+        if (pcie_cap_has_rtctl(dev->pcie_type, flags))
+                pci_read_config_word(dev, pos + PCI_EXP_RTCTL, &cap[i++]);
+        if (pcie_cap_has_devctl2(dev->pcie_type, flags))
+                pci_read_config_word(dev, pos + PCI_EXP_DEVCTL2, &cap[i++]);
+        if (pcie_cap_has_lnkctl2(dev->pcie_type, flags))
+                pci_read_config_word(dev, pos + PCI_EXP_LNKCTL2, &cap[i++]);
+        if (pcie_cap_has_sltctl2(dev->pcie_type, flags))
+                pci_read_config_word(dev, pos + PCI_EXP_SLTCTL2, &cap[i++]);
 
         return 0;
 }
@@ -714,6 +746,7 @@ static void pci_restore_pcie_state(struct pci_dev *dev)
         int i = 0, pos;
         struct pci_cap_saved_state *save_state;
         u16 *cap;
+        u16 flags;
 
         save_state = pci_find_saved_cap(dev, PCI_CAP_ID_EXP);
         pos = pci_find_capability(dev, PCI_CAP_ID_EXP);
@@ -721,13 +754,22 @@ static void pci_restore_pcie_state(struct pci_dev *dev)
                 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_write_config_word(dev, pos + PCI_EXP_DEVCTL2, cap[i++]);
-        pci_write_config_word(dev, pos + PCI_EXP_LNKCTL2, cap[i++]);
-        pci_write_config_word(dev, pos + PCI_EXP_SLTCTL2, cap[i++]);
+        pci_read_config_word(dev, pos + PCI_EXP_FLAGS, &flags);
+
+        if (pcie_cap_has_devctl(dev->pcie_type, flags))
+                pci_write_config_word(dev, pos + PCI_EXP_DEVCTL, cap[i++]);
+        if (pcie_cap_has_lnkctl(dev->pcie_type, flags))
+                pci_write_config_word(dev, pos + PCI_EXP_LNKCTL, cap[i++]);
+        if (pcie_cap_has_sltctl(dev->pcie_type, flags))
+                pci_write_config_word(dev, pos + PCI_EXP_SLTCTL, cap[i++]);
+        if (pcie_cap_has_rtctl(dev->pcie_type, flags))
+                pci_write_config_word(dev, pos + PCI_EXP_RTCTL, cap[i++]);
+        if (pcie_cap_has_devctl2(dev->pcie_type, flags))
+                pci_write_config_word(dev, pos + PCI_EXP_DEVCTL2, cap[i++]);
+        if (pcie_cap_has_lnkctl2(dev->pcie_type, flags))
+                pci_write_config_word(dev, pos + PCI_EXP_LNKCTL2, cap[i++]);
+        if (pcie_cap_has_sltctl2(dev->pcie_type, flags))
+                pci_write_config_word(dev, pos + PCI_EXP_SLTCTL2, cap[i++]);
 }