PCI: pciehp: Add reset_slot() method

PCIe hotplug has a bus per slot, so we can just use a normal
secondary bus reset.  However, if a slot supports surprise removal,
a bus reset can be seen as a presence detection change triggering
a hot-remove followed by a hot-add.  Disable presence detection from
triggering an interrupt or being polled around the bus reset.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

3 files changed, 44 insertions, 0 deletions

diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h
index 7fb326983ed6..541bbe6d5343 100644
--- a/drivers/pci/hotplug/pciehp.h
+++ b/drivers/pci/hotplug/pciehp.h
@@ -155,6 +155,7 @@ void pciehp_green_led_off(struct slot *slot);
 void pciehp_green_led_blink(struct slot *slot);
 int pciehp_check_link_status(struct controller *ctrl);
 void pciehp_release_ctrl(struct controller *ctrl);
+int pciehp_reset_slot(struct slot *slot, int probe);
 
 static inline const char *slot_name(struct slot *slot)
 {
diff --git a/drivers/pci/hotplug/pciehp_core.c b/drivers/pci/hotplug/pciehp_core.c
index 7d72c5e2eba9..f4a18f51a29c 100644
--- a/drivers/pci/hotplug/pciehp_core.c
+++ b/drivers/pci/hotplug/pciehp_core.c
@@ -69,6 +69,7 @@ static int get_power_status	(struct hotplug_slot *slot, u8 *value);
 static int get_attention_status (struct hotplug_slot *slot, u8 *value);
 static int get_latch_status     (struct hotplug_slot *slot, u8 *value);
 static int get_adapter_status   (struct hotplug_slot *slot, u8 *value);
+static int reset_slot           (struct hotplug_slot *slot, int probe);
 
 /**
  * release_slot - free up the memory used by a slot
@@ -111,6 +112,7 @@ static int init_slot(struct controller *ctrl)
         ops->disable_slot = disable_slot;
         ops->get_power_status = get_power_status;
         ops->get_adapter_status = get_adapter_status;
+        ops->reset_slot = reset_slot;
         if (MRL_SENS(ctrl))
                 ops->get_latch_status = get_latch_status;
         if (ATTN_LED(ctrl)) {
@@ -223,6 +225,16 @@ static int get_adapter_status(struct hotplug_slot *hotplug_slot, u8 *value)
         return pciehp_get_adapter_status(slot, value);
 }
 
+static int reset_slot(struct hotplug_slot *hotplug_slot, int probe)
+{
+        struct slot *slot = hotplug_slot->private;
+
+        ctrl_dbg(slot->ctrl, "%s: physical_slot = %s\n",
+                 __func__, slot_name(slot));
+
+        return pciehp_reset_slot(slot, probe);
+}
+
 static int pciehp_probe(struct pcie_device *dev)
 {
         int rc;
diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index b2255736ac81..51f56ef4ab6f 100644
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -749,6 +749,37 @@ static void pcie_disable_notification(struct controller *ctrl)
                 ctrl_warn(ctrl, "Cannot disable software notification\n");
 }
 
+/*
+ * pciehp has a 1:1 bus:slot relationship so we ultimately want a secondary
+ * bus reset of the bridge, but if the slot supports surprise removal we need
+ * to disable presence detection around the bus reset and clear any spurious
+ * events after.
+ */
+int pciehp_reset_slot(struct slot *slot, int probe)
+{
+        struct controller *ctrl = slot->ctrl;
+
+        if (probe)
+                return 0;
+
+        if (HP_SUPR_RM(ctrl)) {
+                pcie_write_cmd(ctrl, 0, PCI_EXP_SLTCTL_PDCE);
+                if (pciehp_poll_mode)
+                        del_timer_sync(&ctrl->poll_timer);
+        }
+
+        pci_reset_bridge_secondary_bus(ctrl->pcie->port);
+
+        if (HP_SUPR_RM(ctrl)) {
+                pciehp_writew(ctrl, PCI_EXP_SLTSTA, PCI_EXP_SLTSTA_PDC);
+                pcie_write_cmd(ctrl, PCI_EXP_SLTCTL_PDCE, PCI_EXP_SLTCTL_PDCE);
+                if (pciehp_poll_mode)
+                        int_poll_timeout(ctrl->poll_timer.data);
+        }
+
+        return 0;
+}
+
 int pcie_init_notification(struct controller *ctrl)
 {
         if (pciehp_request_irq(ctrl))