[PATCH v2 3/3] PCI/AER: Provide reset_link for firmware first root port

Betty Dall
2013-05-30T14:39:29Z

The firmware first path does not install the aerdrv root port
service driver, so the firmware first root port does not have
a reset_link callback. When a firmware first root port does not have
a reset_link callback, use a new default reset_link similar to what
we already do for the default_downstream_reset_link(). The firmware
first default reset_link brings the root port out of SBR if firmware
left it in SBR.

Changes since v1:
Removed incorrect setting of p2p_ctrl after the read.

Signed-off-by: Betty Dall <betty.dall@hp.com>
---

drivers/pci/pcie/aer/aerdrv_core.c | 36 ++++++++++++++++++++++++++++++++++++
1 files changed, 36 insertions(+), 0 deletions(-)

diff --git a/drivers/pci/pcie/aer/aerdrv_core.c b/drivers/pci/pcie/aer/aerdrv_core.c
index 8ec8b4f..72f76cd 100644
--- a/drivers/pci/pcie/aer/aerdrv_core.c
+++ b/drivers/pci/pcie/aer/aerdrv_core.c
@@ -413,6 +413,39 @@ static pci_ers_result_t default_downstream_reset_link(struct pci_dev *dev)
return PCI_ERS_RESULT_RECOVERED;
}

+/**
+ * default_ff_root_port_reset_link - default reset function for firmware
+ * first Root Port
+ * @dev: pointer to root port's pci_dev data structure
+ *
+ * Invoked when performing link reset at Root Port w/ no aer driver.
+ * This happens through the firmware first path. Firmware may leave
+ * the Root Port in SBR and it is the OS responsiblity to bring it out
+ * of SBR.
+ */
+static pci_ers_result_t default_ff_root_port_reset_link(struct pci_dev *dev)
+{
+ u16 p2p_ctrl;
+
+ /* Read Secondary Bus Reset */
+ pci_read_config_word(dev, PCI_BRIDGE_CONTROL, &p2p_ctrl);
+
+ /* De-assert Secondary Bus Reset, if it is set */
+ if (p2p_ctrl & PCI_BRIDGE_CTL_BUS_RESET) {
+ p2p_ctrl &= ~PCI_BRIDGE_CTL_BUS_RESET;
+ pci_write_config_word(dev, PCI_BRIDGE_CONTROL, p2p_ctrl);
+
+ /*
+ * System software must wait for at least 100ms from the end
+ * of a reset of one or more device before it is permitted
+ * to issue Configuration Requests to those devices.
+ */
+ msleep(200);
+ dev_dbg(&dev->dev, "Root Port link has been reset\n");
+ }
+ return PCI_ERS_RESULT_RECOVERED;
+}
+
static int find_aer_service_iter(struct device *device, void *data)
{
struct pcie_port_service_driver *service_driver, **drv;
@@ -460,6 +493,9 @@ static pci_ers_result_t reset_link(struct pci_dev *dev)
status = driver->reset_link(udev);
} else if (pci_pcie_type(udev) == PCI_EXP_TYPE_DOWNSTREAM) {
status = default_downstream_reset_link(udev);
+ } else if (pci_pcie_type(udev) == PCI_EXP_TYPE_ROOT_PORT &&
+ pcie_aer_get_firmware_first(udev)) {
+ status = default_ff_root_port_reset_link(udev);
} else {
dev_printk(KERN_DEBUG, &dev->dev,
"no link-reset support at upstream device %s\n",