[RFC PATCH 3/6] pci bus async shutdown support

[David Jeffery <djeffery@xxxxxxxxxx>]

Add async shutdown shutdown fields and Convert pci's shutdown logic into
async shutdown calls so that individual pci device drivers can implement
async shutdown.

Signed-off-by: David Jeffery <djeffery@xxxxxxxxxx>
Tested-by:     Laurence Oberman <loberman@xxxxxxxxxx>

---
 drivers/pci/pci-driver.c | 24 ++++++++++++++++++++++--
 include/linux/pci.h      |  4 ++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 51ec9e7e784f..0ad418905115 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -502,16 +502,28 @@ static void pci_device_remove(struct device *dev)
 	pci_dev_put(pci_dev);
 }
 
-static void pci_device_shutdown(struct device *dev)
+static void pci_device_async_shutdown_start(struct device *dev)
 {
 	struct pci_dev *pci_dev = to_pci_dev(dev);
 	struct pci_driver *drv = pci_dev->driver;
 
 	pm_runtime_resume(dev);
 
-	if (drv && drv->shutdown)
+	if (drv && drv->async_shutdown_start)
+		drv->async_shutdown_start(pci_dev);
+	else if (drv && drv->shutdown)
 		drv->shutdown(pci_dev);
 
+}
+
+static void pci_device_async_shutdown_end(struct device *dev)
+{
+	struct pci_dev *pci_dev = to_pci_dev(dev);
+	struct pci_driver *drv = pci_dev->driver;
+
+	if (drv && drv->async_shutdown_end)
+		drv->async_shutdown_end(pci_dev);
+
 	/*
 	 * If this is a kexec reboot, turn off Bus Master bit on the
 	 * device to tell it to not continue to do DMA. Don't touch
@@ -523,6 +535,12 @@ static void pci_device_shutdown(struct device *dev)
 		pci_clear_master(pci_dev);
 }
 
+static void pci_device_shutdown(struct device *dev)
+{
+	pci_device_async_shutdown_start(dev);
+	pci_device_async_shutdown_end(dev);
+}
+
 #ifdef CONFIG_PM_SLEEP
 
 /* Auxiliary functions used for system resume */
@@ -1682,6 +1700,8 @@ struct bus_type pci_bus_type = {
 	.probe		= pci_device_probe,
 	.remove		= pci_device_remove,
 	.shutdown	= pci_device_shutdown,
+	.async_shutdown_start	= pci_device_async_shutdown_start,
+	.async_shutdown_end	= pci_device_async_shutdown_end,
 	.dev_groups	= pci_dev_groups,
 	.bus_groups	= pci_bus_groups,
 	.drv_groups	= pci_drv_groups,
diff --git a/include/linux/pci.h b/include/linux/pci.h
index add9368e6314..6f61325c956a 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -917,6 +917,8 @@ struct module;
  *		Useful for enabling wake-on-lan (NIC) or changing
  *		the power state of a device before reboot.
  *		e.g. drivers/net/e100.c.
+ * @async_shutdown_start:	This starts the asynchronous shutdown
+ * @async_shutdown_end:	This completes the started asynchronous shutdown
  * @sriov_configure: Optional driver callback to allow configuration of
  *		number of VFs to enable via sysfs "sriov_numvfs" file.
  * @sriov_set_msix_vec_count: PF Driver callback to change number of MSI-X
@@ -947,6 +949,8 @@ struct pci_driver {
 	int  (*suspend)(struct pci_dev *dev, pm_message_t state);	/* Device suspended */
 	int  (*resume)(struct pci_dev *dev);	/* Device woken up */
 	void (*shutdown)(struct pci_dev *dev);
+	void (*async_shutdown_start)(struct pci_dev *dev);
+	void (*async_shutdown_end)(struct pci_dev *dev);
 	int  (*sriov_configure)(struct pci_dev *dev, int num_vfs); /* On PF */
 	int  (*sriov_set_msix_vec_count)(struct pci_dev *vf, int msix_vec_count); /* On PF */
 	u32  (*sriov_get_vf_total_msix)(struct pci_dev *pf);
-- 
2.43.0