[PATCHv2 1/2] PCI: Device driver reset notification

[Keith Busch <keith.busch@intel.com>]

Notifies a pci device driver when its device's access is about to be
disabled for an impending reset attempt, then after the attempt completes
and device access is restored.

Signed-off-by: Keith Busch <keith.busch@intel.com>
---
v1 -> v2:

Call the reset notification in all cases before device access is disabled
and after device access is restored.

 drivers/pci/pci.c   |   21 +++++++++++++++++++++
 include/linux/pci.h |    3 +++
 2 files changed, 24 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 7325d43..43d87b2 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3305,8 +3305,27 @@ static void pci_dev_unlock(struct pci_dev *dev)
 	pci_cfg_access_unlock(dev);
 }
 
+/**
+ * pci_reset_notify - notify device driver of reset
+ * @dev: device to be notified of reset
+ * @prepare: 'true' if device is about to be reset; 'false' if reset attempt
+ *           completed
+ *
+ * Must be called prior to device access being disabled and after device
+ * access is restored.
+ */
+static void pci_reset_notify(struct pci_dev *dev, bool prepare)
+{
+	const struct pci_error_handlers *err_handler =
+			dev->driver ? dev->driver->err_handler : NULL;
+	if (err_handler && err_handler->reset_notify)
+		err_handler->reset_notify(dev, prepare);
+}
+
 static void pci_dev_save_and_disable(struct pci_dev *dev)
 {
+	pci_reset_notify(dev, true);
+
 	/*
 	 * Wake-up device prior to save.  PM registers default to D0 after
 	 * reset and a simple register restore doesn't reliably return
@@ -3328,6 +3347,7 @@ static void pci_dev_save_and_disable(struct pci_dev *dev)
 static void pci_dev_restore(struct pci_dev *dev)
 {
 	pci_restore_state(dev);
+	pci_reset_notify(dev, false);
 }
 
 static int pci_dev_reset(struct pci_dev *dev, int probe)
@@ -3344,6 +3364,7 @@ static int pci_dev_reset(struct pci_dev *dev, int probe)
 
 	return rc;
 }
+
 /**
  * __pci_reset_function - reset a PCI device function
  * @dev: PCI device to reset
diff --git a/include/linux/pci.h b/include/linux/pci.h
index aab57b4..31c4309 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -603,6 +603,9 @@ struct pci_error_handlers {
 	/* PCI slot has been reset */
 	pci_ers_result_t (*slot_reset)(struct pci_dev *dev);
 
+	/* PCI function reset prepare or completed */
+	void (*reset_notify)(struct pci_dev *dev, bool prepare);
+
 	/* Device driver may resume normal operations */
 	void (*resume)(struct pci_dev *dev);
 };
-- 
1.7.10.4