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>

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 6a052ad..2e58acc 100644 (file)
--- 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);