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