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

Greg KH
2011-09-07T18:47:50Z

On Wed, Sep 07, 2011 at 05:41:45PM +0200, Joerg Roedel wrote:
> 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 | 16 ++++++++++++++++
> drivers/iommu/iommu.c | 4 ++++
> include/linux/device.h | 9 +++++++++
> include/linux/iommu.h | 2 ++
> 4 files changed, 31 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/base/bus.c b/drivers/base/bus.c
> index 000e7b2..34ac706 100644
> --- a/drivers/base/bus.c
> +++ b/drivers/base/bus.c
> @@ -1028,6 +1028,22 @@ void bus_sort_breadthfirst(struct bus_type *bus,
> }
> EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
>
> +#ifdef CONFIG_IOMMU_API
> +int bus_set_iommu(struct bus_type *bus, struct iommu_ops *ops)
> +{
> + if (bus->iommu_ops != NULL)
> + return -EBUSY;

Busy?

> +
> + 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);

I don't understand what this function is for, and who would call it.

Please provide kerneldoc that explains this.

> +#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

So why is this just not set by the bus itself, making the above function
not needed at all?

confused,

greg k-h