Re: [PATCH 1/1] ARM: tegra: bus_notifier registers IOMMU devices

[Hiroshi Doyu <hdoyu@nvidia.com>]

Mark Zhang <nvmarkzhang@gmail.com> wrote @ Fri, 30 Nov 2012 05:59:32 +0100:

> On 11/28/2012 09:48 PM, Hiroshi Doyu wrote:
> > Hiroshi Doyu <hdoyu@nvidia.com> wrote @ Mon, 24 Sep 2012 14:50:14 +0300 (EEST):
> > ...
> >>>>> On Mon, 2012-09-24 at 12:04 +0300, Hiroshi Doyu wrote:
> >>>>>> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> >>>>>> index a1a7225..9eae3be 100644
> >>>>>> --- a/drivers/base/platform.c
> >>>>>> +++ b/drivers/base/platform.c
> >>>>>> @@ -21,6 +21,8 @@
> >>>>>>  #include <linux/slab.h>
> >>>>>>  #include <linux/pm_runtime.h>
> >>>>>>
> >>>>>> +#include <asm/dma-iommu.h>
> >>>>>> +
> >>>>>>  #include "base.h"
> >>>>>>
> >>>>>>  #define to_platform_driver(drv)        (container_of((drv), struct
> >>>>>> platform_driver, \
> >>>>>> @@ -305,8 +307,19 @@ int platform_device_add(struct platform_device
> >>>>>> *pdev)
> >>>>>>                  dev_name(&pdev->dev), dev_name(pdev->dev.parent));
> >>>>>>
> >>>>>>         ret = device_add(&pdev->dev);
> >>>>>> -       if (ret == 0)
> >>>>>> -               return ret;
> >>>>>> +       if (ret)
> >>>>>> +               goto failed;
> >>>>>> +
> >>>>>> +#ifdef CONFIG_PLATFORM_ENABLE_IOMMU
> >>>>>> +       if (platform_bus_type.map && !pdev->dev.archdata.mapping) {
> >>>>>> +               ret = arm_iommu_attach_device(&pdev->dev,
> >>>>>> +                                             platform_bus_type.map);
> >>>>>> +               if (ret)
> >>>>>> +                       goto failed;
> >>>>>
> >>>>> This is horrible ... you're adding an architecture specific callback
> >>>>> into our generic code; that's really a no-no.  If the concept of
> >>>>> CONFIG_PLATFORM_ENABE_IOMMU is useful to more than just arm, then this
> >>>>> could become a generic callback.
> >>>>
> >>>> As mentioned in the original, this is a heck to explain what is
> >>>> needed. I am looking for some generic solution for how to specify
> >>>> IOMMU info for each platform devices. I'm guessing that some other SoC
> >>>> may have the similar requirements on the above. As you mentioned, this
> >>>> solution should be a generic, not arch specific.
> >>>
> >>> Please read more about bus notifiers. IMHO a good example is provided in 
> >>> the following thread:
> >>> http://www.mail-archive.com/linux-samsung-soc@vger.kernel.org/msg12238.html
> >>
> >> This bus notifier seems enough flexible to afford the variation of
> >> IOMMU map info, like Tegra ASID, which could be platform-specific, and
> >> the other could be common too. There's already iommu_bus_notifier
> >> too. I'll try to implement something base on this.
> > 
> > Experimentally implemented as below. With the followig patch, each
> > device could specify its own map in DT, and automatically the device
> > would be attached to the map.
> > 
> > There is a case that some devices share a map. This patch doesn't
> > suppor such case yet.
> > 
> > From 8cb75bb6f3a8535a077e0e85265f87c1f1289bfd Mon Sep 17 00:00:00 2001
> > From: Hiroshi Doyu <hdoyu@nvidia.com>
> > Date: Wed, 28 Nov 2012 14:47:04 +0200
> > Subject: [PATCH 1/1] ARM: tegra: bus_notifier registers IOMMU devices
> > 
> > platform_bus notifier registers IOMMU devices if dma-window is
> > specified.
> > 
> > Its format is:
> >   dma-window = <"start" "size">;
> > ex)
> >   dma-window = <0x12345000 0x8000>;
> > 
> > Signed-off-by: Hiroshi Doyu <hdoyu@nvidia.com>
> > ---
> >  arch/arm/mach-tegra/board-dt-tegra30.c |   40 ++++++++++++++++++++++++++++++++
> >  1 file changed, 40 insertions(+)
> > 
> > diff --git a/arch/arm/mach-tegra/board-dt-tegra30.c b/arch/arm/mach-tegra/board-dt-tegra30.c
> > index a2b6cf1..570d718 100644
> > --- a/arch/arm/mach-tegra/board-dt-tegra30.c
> > +++ b/arch/arm/mach-tegra/board-dt-tegra30.c
> > @@ -30,9 +30,11 @@
> >  #include <linux/of_fdt.h>
> >  #include <linux/of_irq.h>
> >  #include <linux/of_platform.h>
> > +#include <linux/of_iommu.h>
> >  
> >  #include <asm/mach/arch.h>
> >  #include <asm/hardware/gic.h>
> > +#include <asm/dma-iommu.h>
> >  
> >  #include "board.h"
> >  #include "clock.h"
> > @@ -86,10 +88,48 @@ static __initdata struct tegra_clk_init_table tegra_dt_clk_init_table[] = {
> >  	{ NULL,		NULL,		0,		0},
> >  };
> >  
> > +#ifdef CONFIG_ARM_DMA_USE_IOMMU
> > +static int tegra_iommu_device_notifier(struct notifier_block *nb,
> > +				       unsigned long event, void *_dev)
> > +{
> > +	struct dma_iommu_mapping *map = NULL;
> > +	struct device *dev = _dev;
> > +	dma_addr_t base;
> > +	size_t size;
> > +	int err;
> > +
> > +	switch (event) {
> > +	case BUS_NOTIFY_ADD_DEVICE:
> > +		err = of_get_dma_window(dev->of_node, NULL, 0, NULL, &base,
> > +					&size);
> > +		if (!err)
> > +			map = arm_iommu_create_mapping(&platform_bus_type,
> > +						       base, size, 0);
> > +		if (IS_ERR_OR_NULL(map))
> > +			break;
> > +		if (arm_iommu_attach_device(dev, map))
> 
> Add "arm_iommu_release_mapping" here.

Yes.

> And finally we see this patch, that's great. :)

I'll move the location of patch to drivers/iommu/tegra-smmu.c and repost.

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