PCI: Extend pci_reset_function() to support PCI Advanced Features

Some PCI devices implement PCI Advanced Features, which means they
support Function Level Reset(FLR).  Implement support for that in
pci_reset_function.

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

1 files changed, 41 insertions, 0 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 62978f644a92..3c2fa2fdc9cd 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1789,6 +1789,43 @@ static int __pcie_flr(struct pci_dev *dev, int probe)
         return 0;
 }
 
+static int __pci_af_flr(struct pci_dev *dev, int probe)
+{
+        int cappos = pci_find_capability(dev, PCI_CAP_ID_AF);
+        u8 status;
+        u8 cap;
+
+        if (!cappos)
+                return -ENOTTY;
+        pci_read_config_byte(dev, cappos + PCI_AF_CAP, &cap);
+        if (!(cap & PCI_AF_CAP_TP) || !(cap & PCI_AF_CAP_FLR))
+                return -ENOTTY;
+
+        if (probe)
+                return 0;
+
+        pci_block_user_cfg_access(dev);
+
+        /* Wait for Transaction Pending bit clean */
+        msleep(100);
+        pci_read_config_byte(dev, cappos + PCI_AF_STATUS, &status);
+        if (status & PCI_AF_STATUS_TP) {
+                dev_info(&dev->dev, "Busy after 100ms while trying to"
+                                " reset; sleeping for 1 second\n");
+                ssleep(1);
+                pci_read_config_byte(dev,
+                                cappos + PCI_AF_STATUS, &status);
+                if (status & PCI_AF_STATUS_TP)
+                        dev_info(&dev->dev, "Still busy after 1s; "
+                                        "proceeding with reset anyway\n");
+        }
+        pci_write_config_byte(dev, cappos + PCI_AF_CTRL, PCI_AF_CTRL_FLR);
+        mdelay(100);
+
+        pci_unblock_user_cfg_access(dev);
+        return 0;
+}
+
 static int __pci_reset_function(struct pci_dev *pdev, int probe)
 {
         int res;
@@ -1797,6 +1834,10 @@ static int __pci_reset_function(struct pci_dev *pdev, int probe)
         if (res != -ENOTTY)
                 return res;
 
+        res = __pci_af_flr(pdev, probe);
+        if (res != -ENOTTY)
+                return res;
+
         return res;
 }