linux-kernel - [PATCH] powerpc/pseries: Add shutdown() to vio_driver and vio

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Date:   Thu,  1 Apr 2021 18:13:25 -0600
From:   Tyrel Datwyler <tyreld@...ux.ibm.com>
To:     mpe@...erman.id.au
Cc:     benh@...nel.crashing.org, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, Tyrel Datwyler <tyreld@...ux.ibm.com>
Subject: [PATCH] powerpc/pseries: Add shutdown() to vio_driver and vio_bus

Currently, neither the vio_bus or vio_driver structures provide support
for a shutdown() routine.

Add support for shutdown() by allowing drivers to provide a
implementation via function pointer in their vio_driver struct and
provide a proper implementation in the driver template for the vio_bus
that calls a vio drivers shutdown() if defined.

In the case that no shutdown() is defined by a vio driver and a kexec is
in progress we implement a big hammer that calls remove() to ensure no
further DMA for the devices is possible.

Signed-off-by: Tyrel Datwyler <tyreld@...ux.ibm.com>
---
 arch/powerpc/include/asm/vio.h       |  1 +
 arch/powerpc/platforms/pseries/vio.c | 16 ++++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/arch/powerpc/include/asm/vio.h b/arch/powerpc/include/asm/vio.h
index 721c0d6715ac..e7479a4abf96 100644
--- a/arch/powerpc/include/asm/vio.h
+++ b/arch/powerpc/include/asm/vio.h
@@ -114,6 +114,7 @@ struct vio_driver {
 	const struct vio_device_id *id_table;
 	int (*probe)(struct vio_dev *dev, const struct vio_device_id *id);
 	void (*remove)(struct vio_dev *dev);
+	void (*shutdown)(struct vio_dev *dev);
 	/* A driver must have a get_desired_dma() function to
 	 * be loaded in a CMO environment if it uses DMA.
 	 */
diff --git a/arch/powerpc/platforms/pseries/vio.c b/arch/powerpc/platforms/pseries/vio.c
index 9cb4fc839fd5..d122b8644319 100644
--- a/arch/powerpc/platforms/pseries/vio.c
+++ b/arch/powerpc/platforms/pseries/vio.c
@@ -22,6 +22,7 @@
 #include <linux/mm.h>
 #include <linux/dma-map-ops.h>
 #include <linux/kobject.h>
+#include <linux/kexec.h>
 
 #include <asm/iommu.h>
 #include <asm/dma.h>
@@ -1278,6 +1279,20 @@ static int vio_bus_remove(struct device *dev)
 	return 0;
 }
 
+static void vio_bus_shutdown(struct device *dev)
+{
+	struct vio_dev *viodev = to_vio_dev(dev);
+	struct vio_driver *viodrv;
+
+	if (dev->driver) {
+		viodrv = to_vio_driver(dev->driver);
+		if (viodrv->shutdown)
+			viodrv->shutdown(viodev);
+		else if (kexec_in_progress)
+			vio_bus_remove(dev);
+	}
+}
+
 /**
  * vio_register_driver: - Register a new vio driver
  * @viodrv:	The vio_driver structure to be registered.
@@ -1613,6 +1628,7 @@ struct bus_type vio_bus_type = {
 	.match = vio_bus_match,
 	.probe = vio_bus_probe,
 	.remove = vio_bus_remove,
+	.shutdown = vio_bus_shutdown,
 };
 
 /**
-- 
2.27.0