linux-kernel - Re: [PATCH 02/10] Driver core: Add iommu_ops to bus

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Message-ID: <20110907184750.GA920@suse.de>
Date:	Wed, 7 Sep 2011 11:47:50 -0700
From:	Greg KH <gregkh@...e.de>
To:	Joerg Roedel <joerg.roedel@....com>
Cc:	iommu@...ts.linux-foundation.org,
	Alex Williamson <alex.williamson@...hat.com>,
	Ohad Ben-Cohen <ohad@...ery.com>,
	David Woodhouse <dwmw2@...radead.org>,
	David Brown <davidb@...eaurora.org>, joro@...tes.org,
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 02/10] Driver core: Add iommu_ops to bus_type

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@....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
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