PCI: add support for function level reset

Sometimes, it's necessary to enable software's ability to quiesce and
reset endpoint hardware with function-level granularity, so provide
support for it.

The patch implement Function Level Reset(FLR) feature following PCI-e
spec. And this is the first step. We would add more generic method, like
D0/D3, to allow more devices support this function.

The patch contains two functions. pcie_reset_function() is the new
driver API, and, contains some action to quiesce a device.  The other
function is a helper:  pcie_execute_reset_function() just executes the
reset for a particular device function.

Current the usage model is in KVM. Function reset is necessary for
assigning device to a guest, or moving it between partitions.

For Function Level Reset(FLR), please refer to PCI Express spec chapter
6.6.2.

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

2 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 085187be29c..f6f6810296e 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -626,6 +626,8 @@ int pcix_get_mmrbc(struct pci_dev *dev);
 int pcix_set_mmrbc(struct pci_dev *dev, int mmrbc);
 int pcie_get_readrq(struct pci_dev *dev);
 int pcie_set_readrq(struct pci_dev *dev, int rq);
+int pci_reset_function(struct pci_dev *dev);
+int pci_execute_reset_function(struct pci_dev *dev);
 void pci_update_resource(struct pci_dev *dev, struct resource *res, int resno);
 int __must_check pci_assign_resource(struct pci_dev *dev, int i);
 int pci_select_bars(struct pci_dev *dev, unsigned long flags);
diff --git a/include/linux/pci_regs.h b/include/linux/pci_regs.h
index eb6686b88f9..e5effd47ed7 100644
--- a/include/linux/pci_regs.h
+++ b/include/linux/pci_regs.h
@@ -377,6 +377,7 @@
 #define  PCI_EXP_DEVCAP_RBER    0x8000  /* Role-Based Error Reporting */
 #define  PCI_EXP_DEVCAP_PWR_VAL 0x3fc0000 /* Slot Power Limit Value */
 #define  PCI_EXP_DEVCAP_PWR_SCL 0xc000000 /* Slot Power Limit Scale */
+#define  PCI_EXP_DEVCAP_FLR     0x10000000 /* Function Level Reset */
 #define PCI_EXP_DEVCTL          8       /* Device Control */
 #define  PCI_EXP_DEVCTL_CERE    0x0001  /* Correctable Error Reporting En. */
 #define  PCI_EXP_DEVCTL_NFERE   0x0002  /* Non-Fatal Error Reporting Enable */
@@ -389,6 +390,7 @@
 #define  PCI_EXP_DEVCTL_AUX_PME 0x0400  /* Auxiliary Power PM Enable */
 #define  PCI_EXP_DEVCTL_NOSNOOP_EN 0x0800  /* Enable No Snoop */
 #define  PCI_EXP_DEVCTL_READRQ  0x7000  /* Max_Read_Request_Size */
+#define  PCI_EXP_DEVCTL_BCR_FLR 0x8000  /* Bridge Configuration Retry / FLR */
 #define PCI_EXP_DEVSTA          10      /* Device Status */
 #define  PCI_EXP_DEVSTA_CED     0x01    /* Correctable Error Detected */
 #define  PCI_EXP_DEVSTA_NFED    0x02    /* Non-Fatal Error Detected */