Re: [PATCH 02/10] Driver core: Add iommu_ops to bus_type

["Roedel, Joerg" <Joerg.Roedel@amd.com>]

Hi Greg,

On Wed, Sep 07, 2011 at 03:44:45PM -0400, Greg KH wrote:
> > 
> > The IOMMUs are usually devices on the bus itself, so they are
> > initialized after the bus is set up and the devices on it are
> > populated.  So the function can not be called on bus initialization
> > because the IOMMU is not ready at this point.
> 
> Ok, that makes more sense, please state as much in the documentation.

I added the kernel-doc documentation you requested. Here is the updated
patch. Please let me know what you think.

>From 23757825035f6d9309866dc142133aada0e2c1de Mon Sep 17 00:00:00 2001
From: Joerg Roedel <joerg.roedel@amd.com>
Date: Fri, 26 Aug 2011 16:48:26 +0200
Subject: [PATCH 02/10] Driver core: Add iommu_ops to bus_type

This is the starting point to make the iommu_ops used for
the iommu-api a per-bus-type structure. It is required to
easily implement bus-specific setup in the iommu-layer.
The first user will be the iommu-group attribute in sysfs.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
---
 drivers/base/bus.c     |   29 +++++++++++++++++++++++++++++
 drivers/iommu/iommu.c  |    4 ++++
 include/linux/device.h |    9 +++++++++
 include/linux/iommu.h  |    2 ++
 4 files changed, 44 insertions(+), 0 deletions(-)

diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index 000e7b2..b3014fe 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -1028,6 +1028,35 @@ void bus_sort_breadthfirst(struct bus_type *bus,
 }
 EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
 
+#ifdef CONFIG_IOMMU_API
+/**
+ * bus_set_iommu - set iommu-callbacks for the bus
+ * @bus: bus.
+ * @ops: the callbacks provided by the iommu-driver
+ *
+ * This function is called by an iommu driver to set the iommu methods
+ * used for a particular bus. Drivers for devices on that bus can use
+ * the iommu-api after these ops are registered.
+ * This special function is needed because IOMMUs are usually devices on
+ * the bus itself, so the iommu drivers are not initialized when the bus
+ * is set up. With this function the iommu-driver can set the iommu-ops
+ * afterwards.
+ */
+int bus_set_iommu(struct bus_type *bus, struct iommu_ops *ops)
+{
+	if (bus->iommu_ops != NULL)
+		return -EBUSY;
+
+	bus->iommu_ops = ops;
+
+	/* Do IOMMU specific setup for this bus-type */
+	iommu_bus_init(bus, ops);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(bus_set_iommu);
+#endif
+
 int __init buses_init(void)
 {
 	bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 30b0644..3b24a5b 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -34,6 +34,10 @@ void register_iommu(struct iommu_ops *ops)
 	iommu_ops = ops;
 }
 
+void iommu_bus_init(struct bus_type *bus, struct iommu_ops *ops)
+{
+}
+
 bool iommu_found(void)
 {
 	return iommu_ops != NULL;
diff --git a/include/linux/device.h b/include/linux/device.h
index c20dfbf..8240b2a 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -22,6 +22,7 @@
 #include <linux/types.h>
 #include <linux/module.h>
 #include <linux/pm.h>
+#include <linux/iommu.h>
 #include <linux/atomic.h>
 #include <asm/device.h>
 
@@ -67,6 +68,9 @@ extern void bus_remove_file(struct bus_type *, struct bus_attribute *);
  * @resume:	Called to bring a device on this bus out of sleep mode.
  * @pm:		Power management operations of this bus, callback the specific
  *		device driver's pm-ops.
+ * @iommu_ops   IOMMU specific operations for this bus, used to attach IOMMU
+ *              driver implementations to a bus and allow the driver to do
+ *              bus-specific setup
  * @p:		The private data of the driver core, only the driver core can
  *		touch this.
  *
@@ -96,6 +100,8 @@ struct bus_type {
 
 	const struct dev_pm_ops *pm;
 
+	struct iommu_ops *iommu_ops;
+
 	struct subsys_private *p;
 };
 
@@ -148,6 +154,9 @@ extern int bus_unregister_notifier(struct bus_type *bus,
 #define BUS_NOTIFY_UNBOUND_DRIVER	0x00000006 /* driver is unbound
 						      from the device */
 
+/* IOMMU related bus functions */
+int bus_set_iommu(struct bus_type *bus, struct iommu_ops *ops);
+
 extern struct kset *bus_get_kset(struct bus_type *bus);
 extern struct klist *bus_get_device_klist(struct bus_type *bus);
 
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 6470cd8..4739e36 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -25,6 +25,7 @@
 #define IOMMU_WRITE	(2)
 #define IOMMU_CACHE	(4) /* DMA cache coherency */
 
+struct bus_type;
 struct device;
 
 struct iommu_domain {
@@ -52,6 +53,7 @@ struct iommu_ops {
 };
 
 extern void register_iommu(struct iommu_ops *ops);
+extern void iommu_bus_init(struct bus_type *bus, struct iommu_ops *ops);
 extern bool iommu_found(void);
 extern struct iommu_domain *iommu_domain_alloc(void);
 extern void iommu_domain_free(struct iommu_domain *domain);
-- 
1.7.4.1

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