PCI: support PM D0hot->D3 transition reset

PCI PM 1.2 specifies that the device will perform an internal reset upon
transitioning from D3hot to D0 when the NO_SOFT_RESET bit is clear. This
method can be used to reset a function if neither PCIe FLR nor PCI AF FLR
are supported.

Reviewed-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Yu Zhao <yu.zhao@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 34 insertions, 0 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 6a052ada3fe8..2e58acc66a8c 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2132,6 +2132,36 @@ clear:
         return 0;
 }
 
+static int pci_pm_reset(struct pci_dev *dev, int probe)
+{
+        u16 csr;
+
+        if (!dev->pm_cap)
+                return -ENOTTY;
+
+        pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &csr);
+        if (csr & PCI_PM_CTRL_NO_SOFT_RESET)
+                return -ENOTTY;
+
+        if (probe)
+                return 0;
+
+        if (dev->current_state != PCI_D0)
+                return -EINVAL;
+
+        csr &= ~PCI_PM_CTRL_STATE_MASK;
+        csr |= PCI_D3hot;
+        pci_write_config_word(dev, dev->pm_cap + PCI_PM_CTRL, csr);
+        msleep(pci_pm_d3_delay);
+
+        csr &= ~PCI_PM_CTRL_STATE_MASK;
+        csr |= PCI_D0;
+        pci_write_config_word(dev, dev->pm_cap + PCI_PM_CTRL, csr);
+        msleep(pci_pm_d3_delay);
+
+        return 0;
+}
+
 static int pci_dev_reset(struct pci_dev *dev, int probe)
 {
         int rc;
@@ -2149,6 +2179,10 @@ static int pci_dev_reset(struct pci_dev *dev, int probe)
                 goto done;
 
         rc = pci_af_flr(dev, probe);
+        if (rc != -ENOTTY)
+                goto done;
+
+        rc = pci_pm_reset(dev, probe);
 done:
         if (!probe) {
                 up(&dev->dev.sem);