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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
    --
    AMD Operating System Research Center

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    General Managers: Alberto Bozzo, Andrew Bowd
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