[PATCH v7 00/12] iommu/exynos: Fixes and Enhancements of System MMU driver with DT

[PATCH v7 00/12] iommu/exynos: Fixes and Enhancements of System MMU driver with DT

[Cho KyongHo]

The current exynos-iommu(System MMU) driver does not work autonomously
since it is lack of support for power management of peripheral blocks.
For example, MFC device driver must ensure that its System MMU is disabled
before MFC block is power-down not to invalidate IOTLB in the System MMU
when I/O memory mapping is changed. Because A System MMU is resides in the
same H/W block, access to control registers of System MMU while the H/W
block is turned off must be prohibited.

This set of changes solves the above problem with setting each System MMUs
as the parent of the device which owns the System MMU to recieve the
information when the device is turned off or turned on.

Another big change to the driver is the support for devicetree.
The bindings for System MMU is described in
Documentation/devicetree/bindings/arm/samsung/system-mmu.txt

In addition, this patchset also includes several bug fixes and enhancements
of the current driver.

Change log:
v7:
- Rebased on the stable 3.10
- Registered PM domains and gate clocks with DT
- Changed connection method between a System MMU and its master H/W
   'mmu-master' property in the node of System MMU
   --> 'iommu' property in the node of master H/W
- Marking device descriptor of master H/W of a System MMU with bus notifier.
- Power management (PM_RUNTIME, PM_SLEEP) of System MMUs with gpd_dev_ops
   of Generic IO Powerdomain. gpd_dev_ops are set to the master H/Ws
   before they are probed in the bus notifier.
- Removed additional debugging features like debugfs entries and
   version names.
- Removed support for advanced features of System MMU 3.2 and 3.3
   the current IOMMU API cannot handle the feature
  (A kind of L2 TLB that fetches several consequence page table entries.
   It must be initialized by the driver of master H/W whenever it works.)

v6:
- Rebased on the branch, next/iommu-exynos of
  git.kernel.org/pub/scm/linux/kernel/git/kgene/linux-samsung.git

v5:
- new bugfix: patch 01
- Reordered patches
  * patch 01 ~ 05: Bugfix and enhancements of the existing driver
  * patch 06 ~ 10: Device Tree support and callbacks for power management
  * patch 11     : System MMU 3.2 and 3.3 support
  * patch 12 ~ 14: Debugging features
- Additional code compaction

v4:
- Remove Change-Id from v3 patches
- Change the order of the third and the first patch
  Thanks to Kukjin Kim.
- Fix memory leak when allocating and assigning exynos_iommu_owner to client
  device if the client device has multiple System MMUs.
  Thanks to Rahul Sharma.

v3:
- Fix prefetch buffer flag definition for System MMU 3.3 (patch 10/12)
- Fix incorrect setting for SET_RUNTIME_PM_OPS (patch 09/12)
  Thanks to Prathyush.

v2:
- Split the patch to iommu/exynos into 9 patches
- Support for System MMU 3.3
- Some code compaction

Patch summary:
[PATCH v7 1/9] iommu/exynos: do not include removed header
[PATCH v7 2/9] iommu/exynos: add missing cache flush for removed page table entries
[PATCH v7 3/9] iommu/exynos: fix page table maintenance
[PATCH v7 4/9] iommu/exynos: allocate lv2 page table from own slab
[PATCH v7 5/9] iommu/exynos: change rwlock to spinlock
[PATCH v7 6/9] clk: exynos5250: add gate clock descriptions of System MMU
[PATCH v7 7/9] ARM: dts: Add description of System MMU of Exynos SoCs
[PATCH v7 8/9] iommu/exynos: support for device tree
[PATCH v7 9/9] iommu/exynos: add bus notifier for registering System MMU

Diffstats:
.../devicetree/bindings/clock/exynos5250-clock.txt |   28 +-
.../bindings/iommu/samsung,exynos4210-sysmmu.txt   |  103 ++
arch/arm/boot/dts/exynos4.dtsi                     |  122 +++
arch/arm/boot/dts/exynos4210.dtsi                  |   25 +
arch/arm/boot/dts/exynos4x12.dtsi                  |   76 ++
arch/arm/boot/dts/exynos5250.dtsi                  |  291 ++++++
drivers/clk/samsung/clk-exynos5250.c               |   57 +-
drivers/iommu/Kconfig                              |    5 +-
drivers/iommu/exynos-iommu.c                       | 1011 +++++++++++++-------
9 files changed, 1382 insertions(+), 336 deletions(-)

Re: [PATCH v7 00/12] iommu/exynos: Fixes and Enhancements of System MMU driver with DT

[Grant Grundler]

On Fri, Jul 5, 2013 at 5:29 AM, Cho KyongHo <pullip.cho@samsung.com> wrote:
> The current exynos-iommu(System MMU) driver does not work autonomously
> since it is lack of support for power management of peripheral blocks.
...
> Patch summary:
> [PATCH v7 1/9] iommu/exynos: do not include removed header
> [PATCH v7 2/9] iommu/exynos: add missing cache flush for removed page table entries
> [PATCH v7 3/9] iommu/exynos: fix page table maintenance
> [PATCH v7 4/9] iommu/exynos: allocate lv2 page table from own slab
> [PATCH v7 5/9] iommu/exynos: change rwlock to spinlock
> [PATCH v7 6/9] clk: exynos5250: add gate clock descriptions of System MMU
> [PATCH v7 7/9] ARM: dts: Add description of System MMU of Exynos SoCs
> [PATCH v7 8/9] iommu/exynos: support for device tree
> [PATCH v7 9/9] iommu/exynos: add bus notifier for registering System MMU

Cho,
Of the above patches, nearly all have been applied to chromeos-3.8
(kernel-next git tree) by Doug Anderson and others.

AFAICT, the only ones not applied are:
   [v7,3/9] iommu/exynos: fix page table maintenance
   [v7,6/9] clk: exynos5250: add gate clock descriptions of System MMU
(conflicts in this one)
   [v7,7/9] ARM: dts: Add description of System MMU of Exynos SoCs
(depends on 6/9)

We also already have parts of:
   [v7,9/9] iommu/exynos: add bus notifier for registering System MMU

Some of those are being further discussed but I've lost track now
exactly which ones.

I'm telling you about chromeos-3.8 status since the adopted changes
have been reviewed (by me and others) are being tested manually here
on several different Samsung Exynos platforms (including 5250 which is
our "snow" platform). Not sure how you should to mark those patches
since they aren't identical to your changes (which apply to post 3.10
kernels, not 3.8).  You might consider splitting those patches out
from the 4 I've listed above to get that series accepted upstream
since the additional review/testing should provide some confidence
those patches are good.

cheers,
grant

RE: [PATCH v7 00/12] iommu/exynos: Fixes and Enhancements of System MMU driver with DT

[Cho KyongHo]

> From: grundler@google.com [mailto:grundler@google.com] On Behalf Of Grant Grundler
> Sent: Friday, July 12, 2013 2:23 AM
> 
> On Fri, Jul 5, 2013 at 5:29 AM, Cho KyongHo <pullip.cho@samsung.com> wrote:
> > The current exynos-iommu(System MMU) driver does not work autonomously
> > since it is lack of support for power management of peripheral blocks.
> ...
> > Patch summary:
> > [PATCH v7 1/9] iommu/exynos: do not include removed header
> > [PATCH v7 2/9] iommu/exynos: add missing cache flush for removed page table entries
> > [PATCH v7 3/9] iommu/exynos: fix page table maintenance
> > [PATCH v7 4/9] iommu/exynos: allocate lv2 page table from own slab
> > [PATCH v7 5/9] iommu/exynos: change rwlock to spinlock
> > [PATCH v7 6/9] clk: exynos5250: add gate clock descriptions of System MMU
> > [PATCH v7 7/9] ARM: dts: Add description of System MMU of Exynos SoCs
> > [PATCH v7 8/9] iommu/exynos: support for device tree
> > [PATCH v7 9/9] iommu/exynos: add bus notifier for registering System MMU
> 
> Cho,
> Of the above patches, nearly all have been applied to chromeos-3.8
> (kernel-next git tree) by Doug Anderson and others.
> 
> AFAICT, the only ones not applied are:
>    [v7,3/9] iommu/exynos: fix page table maintenance
>    [v7,6/9] clk: exynos5250: add gate clock descriptions of System MMU
> (conflicts in this one)
>    [v7,7/9] ARM: dts: Add description of System MMU of Exynos SoCs
> (depends on 6/9)
> 
> We also already have parts of:
>    [v7,9/9] iommu/exynos: add bus notifier for registering System MMU
> 
> Some of those are being further discussed but I've lost track now
> exactly which ones.
> 
> I'm telling you about chromeos-3.8 status since the adopted changes
> have been reviewed (by me and others) are being tested manually here
> on several different Samsung Exynos platforms (including 5250 which is
> our "snow" platform). Not sure how you should to mark those patches
> since they aren't identical to your changes (which apply to post 3.10
> kernels, not 3.8).  You might consider splitting those patches out
> from the 4 I've listed above to get that series accepted upstream
> since the additional review/testing should provide some confidence
> those patches are good.
> 

I understand what you are concerning about.
Have you applied v6 patchset?

I will try to split the patches and make the changes from v6
on top of the v6 patcheset.

> cheers,
> grant

Thank you.

Cho KyonogHo.

RE: [PATCH v7 00/12] iommu/exynos: Fixes and Enhancements of System MMU driver with DT

[Cho KyongHo]

> From: Cho KyongHo [mailto:pullip.cho@samsung.com]
> Sent: Monday, July 15, 2013 8:24 PM
> 
> > From: grundler@google.com [mailto:grundler@google.com] On Behalf Of Grant Grundler
> > Sent: Friday, July 12, 2013 2:23 AM
> >
> > On Fri, Jul 5, 2013 at 5:29 AM, Cho KyongHo <pullip.cho@samsung.com> wrote:
> > > The current exynos-iommu(System MMU) driver does not work autonomously
> > > since it is lack of support for power management of peripheral blocks.
> > ...
> > > Patch summary:
> > > [PATCH v7 1/9] iommu/exynos: do not include removed header
> > > [PATCH v7 2/9] iommu/exynos: add missing cache flush for removed page table entries
> > > [PATCH v7 3/9] iommu/exynos: fix page table maintenance
> > > [PATCH v7 4/9] iommu/exynos: allocate lv2 page table from own slab
> > > [PATCH v7 5/9] iommu/exynos: change rwlock to spinlock
> > > [PATCH v7 6/9] clk: exynos5250: add gate clock descriptions of System MMU
> > > [PATCH v7 7/9] ARM: dts: Add description of System MMU of Exynos SoCs
> > > [PATCH v7 8/9] iommu/exynos: support for device tree
> > > [PATCH v7 9/9] iommu/exynos: add bus notifier for registering System MMU
> >
> > Cho,
> > Of the above patches, nearly all have been applied to chromeos-3.8
> > (kernel-next git tree) by Doug Anderson and others.
> >
> > AFAICT, the only ones not applied are:
> >    [v7,3/9] iommu/exynos: fix page table maintenance
> >    [v7,6/9] clk: exynos5250: add gate clock descriptions of System MMU
> > (conflicts in this one)
> >    [v7,7/9] ARM: dts: Add description of System MMU of Exynos SoCs
> > (depends on 6/9)
> >
> > We also already have parts of:
> >    [v7,9/9] iommu/exynos: add bus notifier for registering System MMU
> >
> > Some of those are being further discussed but I've lost track now
> > exactly which ones.
> >
> > I'm telling you about chromeos-3.8 status since the adopted changes
> > have been reviewed (by me and others) are being tested manually here
> > on several different Samsung Exynos platforms (including 5250 which is
> > our "snow" platform). Not sure how you should to mark those patches
> > since they aren't identical to your changes (which apply to post 3.10
> > kernels, not 3.8).  You might consider splitting those patches out
> > from the 4 I've listed above to get that series accepted upstream
> > since the additional review/testing should provide some confidence
> > those patches are good.
> >
> 
> I understand what you are concerning about.
> Have you applied v6 patchset?
> 
> I will try to split the patches and make the changes from v6
> on top of the v6 patcheset.
> 

Actually, as you know, the previous patches include setting a System MMU
as the parent device of its master device in probe() of System MMU.
I asked Greg KH about changing device hierarchy in probe() and he answered
that it is not a good idea because it modifies sysfs even though probe() of
System MMU driver is called before sysfs is constructed.

That's why I uses genpd_pm_ops.
It results in big change in the patches after registering device tree.

I want to ask your opinion about this change :)

> > cheers,
> > grant
> 
> Thank you.
> 
> Cho KyonogHo.

Re: [PATCH v7 00/12] iommu/exynos: Fixes and Enhancements of System MMU driver with DT

[Grant Grundler]

On Mon, Jul 15, 2013 at 5:20 AM, Cho KyongHo <pullip.cho@samsung.com> wrote:
...
>> > Cho,
>> > Of the above patches, nearly all have been applied to chromeos-3.8
>> > (kernel-next git tree) by Doug Anderson and others.
>> >
>> > AFAICT, the only ones not applied are:
>> >    [v7,3/9] iommu/exynos: fix page table maintenance
>> >    [v7,6/9] clk: exynos5250: add gate clock descriptions of System MMU
>> > (conflicts in this one)
>> >    [v7,7/9] ARM: dts: Add description of System MMU of Exynos SoCs
>> > (depends on 6/9)
>> >
>> > We also already have parts of:
>> >    [v7,9/9] iommu/exynos: add bus notifier for registering System MMU
>> >
>> > Some of those are being further discussed but I've lost track now
>> > exactly which ones.
>> >
>> > I'm telling you about chromeos-3.8 status since the adopted changes
>> > have been reviewed (by me and others) are being tested manually here
>> > on several different Samsung Exynos platforms (including 5250 which is
>> > our "snow" platform). Not sure how you should to mark those patches
>> > since they aren't identical to your changes (which apply to post 3.10
>> > kernels, not 3.8).  You might consider splitting those patches out
>> > from the 4 I've listed above to get that series accepted upstream
>> > since the additional review/testing should provide some confidence
>> > those patches are good.
>> >
>>
>> I understand what you are concerning about.
>> Have you applied v6 patchset?

I did not though it's possible some of the code that was applied to
chromeos-3.8 kernel came from v6 (or earlier) patches. I just compared
with v7. Since it's a "backport", the code I found in chromeos-3.8 is
the same if not identical to v7.

>>
>> I will try to split the patches and make the changes from v6
>> on top of the v6 patcheset.

Ok.

> Actually, as you know, the previous patches include setting a System MMU
> as the parent device of its master device in probe() of System MMU.
> I asked Greg KH about changing device hierarchy in probe() and he answered
> that it is not a good idea because it modifies sysfs even though probe() of
> System MMU driver is called before sysfs is constructed.

SysMMU primarily provides DMA API, right? Can sysfs be initialized
before DMA is available?
On some (many?) platforms the SysMMU is also responsible for "child"
bus controllers and MMIO resource routing, and on ARM platforms,
clocks for rest of the IO devices.

SysMMU might be needed for early gfx support (or something). Maybe the
right answer is to "discover" the SysMMU twice: once very early to get
the SysMMU operational and then again later in a "normal" probe
sequence to register with the sysfs. Any reason a driver couldn't
register two different module_init() routines in different parts of
the init call table?


> That's why I uses genpd_pm_ops.
> It results in big change in the patches after registering device tree.
>
> I want to ask your opinion about this change :)

I have no objection to large changes if they work well and are easy to
understand.

<rant>
I personally not happy with the direction the Linux IOMMU "subsystem"
has taken. I think the generic IOMMU subsystem should be discarded.
Strong words for someone who's not a key contributor but I'll explain.

I wrote the IOMMU support for PA-RISC (three different IOMMUs) 10+
years ago. I rewrote the HPUX implementations in the 90's and then
around 2000 wrote the implementation for PA-RISC (one of which Alex
Williamson used for IA64 IOMMU support - sba_iommu.c).  It's pretty
straight forward. There is "page allocation policy", code to do TLB
shoot down, and code to manage the IO Pdir. This is the same as for
CPU MMU.  The *efficiency* of the TLB depends on the page allocation
(SW) to work together with the HW TLB replacement policy. In other
words, the page allocation policy needs to avoid thrashing the IO TLB.
A generic IOTLB allocation policy can't do that for every platform.

Exynos 5250 has an 8-way associative TLB. That's likely very different
from the Intel and TI (omap) IOMMU the IOMMU subsystem code was
originally implemented for. The "optimal" size of page to allocate
will be different too.  Older Exynos products are likely different

The "2cd layer" of indirect function calls between the generic IOMMU
support and the platform specific code makes it harder to understand
the code.  While jump tables are good for some things, I don't think
this is a good use. We should "flip" this design around. Let the
platform specific code "own" the DMA ops API and it can decide which
services it should or should not use.

E.g. The IOTLB shoot down can be divorced from the "unmap" call. The
efficiency of shooting down one IOTLB entry at a time is horrible on
most platforms. One answer is to add a new API to shoot down an array
of IOVAs. But the tradeoffs in the size of the array and the events
that might trigger a TLB shoot down should be left up to the
platform/chipset specific code (e.g. "lazy TLB shootdown").

Sorry...this got rant got alot longer than it should have been. I hope
this helps people understand the design tradeoffs that linux IOMMU
subsystem never will be able to cleanly address. My hope is this rant
will help developers like you justify small steps to move away from
generic IOMMU code.
</rant>

cheers,
grant

RE: [PATCH v7 00/12] iommu/exynos: Fixes and Enhancements of System MMU driver with DT

[Cho KyongHo]

> From: grundler@google.com [mailto:grundler@google.com] On Behalf Of Grant Grundler
> Sent: Tuesday, July 16, 2013 12:56 AM
> 
> On Mon, Jul 15, 2013 at 5:20 AM, Cho KyongHo <pullip.cho@samsung.com> wrote:
> ...
> >> > Cho,
> >> > Of the above patches, nearly all have been applied to chromeos-3.8
> >> > (kernel-next git tree) by Doug Anderson and others.
> >> >
> >> > AFAICT, the only ones not applied are:
> >> >    [v7,3/9] iommu/exynos: fix page table maintenance
> >> >    [v7,6/9] clk: exynos5250: add gate clock descriptions of System MMU
> >> > (conflicts in this one)
> >> >    [v7,7/9] ARM: dts: Add description of System MMU of Exynos SoCs
> >> > (depends on 6/9)
> >> >
> >> > We also already have parts of:
> >> >    [v7,9/9] iommu/exynos: add bus notifier for registering System MMU
> >> >
> >> > Some of those are being further discussed but I've lost track now
> >> > exactly which ones.
> >> >
> >> > I'm telling you about chromeos-3.8 status since the adopted changes
> >> > have been reviewed (by me and others) are being tested manually here
> >> > on several different Samsung Exynos platforms (including 5250 which is
> >> > our "snow" platform). Not sure how you should to mark those patches
> >> > since they aren't identical to your changes (which apply to post 3.10
> >> > kernels, not 3.8).  You might consider splitting those patches out
> >> > from the 4 I've listed above to get that series accepted upstream
> >> > since the additional review/testing should provide some confidence
> >> > those patches are good.
> >> >
> >>
> >> I understand what you are concerning about.
> >> Have you applied v6 patchset?
> 
> I did not though it's possible some of the code that was applied to
> chromeos-3.8 kernel came from v6 (or earlier) patches. I just compared
> with v7. Since it's a "backport", the code I found in chromeos-3.8 is
> the same if not identical to v7.
> 
Ok.
I think chromeos-3.8 kernel must work well with v7 also.
But there're a lot of changes in device tree of exynos SoC
and exynos-iommu driver followed by the changes in device tree
since 3.8 kernel.
I worry that back-porting of v7 is not trivial.

> >>
> >> I will try to split the patches and make the changes from v6
> >> on top of the v6 patcheset.
> 
> Ok.
> 
> > Actually, as you know, the previous patches include setting a System MMU
> > as the parent device of its master device in probe() of System MMU.
> > I asked Greg KH about changing device hierarchy in probe() and he answered
> > that it is not a good idea because it modifies sysfs even though probe() of
> > System MMU driver is called before sysfs is constructed.
> 
> SysMMU primarily provides DMA API, right? Can sysfs be initialized
> before DMA is available?
> On some (many?) platforms the SysMMU is also responsible for "child"
> bus controllers and MMIO resource routing, and on ARM platforms,
> clocks for rest of the IO devices.
> 
> SysMMU might be needed for early gfx support (or something). Maybe the
> right answer is to "discover" the SysMMU twice: once very early to get
> the SysMMU operational and then again later in a "normal" probe
> sequence to register with the sysfs. Any reason a driver couldn't
> register two different module_init() routines in different parts of
> the init call table?
> 
I agree with you.
Actually, exynos-iommu driver in Android devices based on 3.4 kernel
sets System MMUs as the parent of their Master devices in the different
initcalls.
(You can find it in the kernel of Galaxy S4 which contains Exynos SoC.)
There are several reasons.
Some devices are not involved in generic IO powerdomain and
genpd_pm_ops is not called for the devices.
Some devices are not proper to handle System MMU with genpd_pm_ops.

I wished that every device which has System MMU uses generic IO powerdomain
for its power management.

If I can be convince myself of that setting System MMU as the parent of
its master device is not a problem, I will not hesitate to do so.

> 
> > That's why I uses genpd_pm_ops.
> > It results in big change in the patches after registering device tree.
> >
> > I want to ask your opinion about this change :)
> 
> I have no objection to large changes if they work well and are easy to
> understand.
> 
Thank you.

> <rant>
> I personally not happy with the direction the Linux IOMMU "subsystem"
> has taken. I think the generic IOMMU subsystem should be discarded.
> Strong words for someone who's not a key contributor but I'll explain.
> 
> I wrote the IOMMU support for PA-RISC (three different IOMMUs) 10+
> years ago. I rewrote the HPUX implementations in the 90's and then
> around 2000 wrote the implementation for PA-RISC (one of which Alex
> Williamson used for IA64 IOMMU support - sba_iommu.c).  It's pretty
> straight forward. There is "page allocation policy", code to do TLB
> shoot down, and code to manage the IO Pdir. This is the same as for
> CPU MMU.  The *efficiency* of the TLB depends on the page allocation
> (SW) to work together with the HW TLB replacement policy. In other
> words, the page allocation policy needs to avoid thrashing the IO TLB.
> A generic IOTLB allocation policy can't do that for every platform.
> 
> Exynos 5250 has an 8-way associative TLB. That's likely very different
> from the Intel and TI (omap) IOMMU the IOMMU subsystem code was
> originally implemented for. The "optimal" size of page to allocate
> will be different too.  Older Exynos products are likely different
> 
> The "2cd layer" of indirect function calls between the generic IOMMU
> support and the platform specific code makes it harder to understand
> the code.  While jump tables are good for some things, I don't think
> this is a good use. We should "flip" this design around. Let the
> platform specific code "own" the DMA ops API and it can decide which
> services it should or should not use.
> 
> E.g. The IOTLB shoot down can be divorced from the "unmap" call. The
> efficiency of shooting down one IOTLB entry at a time is horrible on
> most platforms. One answer is to add a new API to shoot down an array
> of IOVAs. But the tradeoffs in the size of the array and the events
> that might trigger a TLB shoot down should be left up to the
> platform/chipset specific code (e.g. "lazy TLB shootdown").
> 
> Sorry...this got rant got alot longer than it should have been. I hope
> this helps people understand the design tradeoffs that linux IOMMU
> subsystem never will be able to cleanly address. My hope is this rant
> will help developers like you justify small steps to move away from
> generic IOMMU code.
> </rant>
> 
I understand what you are talking about.
Many people including me are finding a way to abstract different types
of H/W. I think IOMMU API is one of the result and DMA mapping framework
for ARM architecture is already finished with IOMMU API.

One of the inefficiency in the current implementation of DMA mapping for
ARM architecture is TLB invalidation which you addressed above.
TLB invalidation interface in IOMMU API was introduced earlier but it was
discarded. We can propose that if any others also agree.

Actually, I defined several custom TLB maintenance interfaces
for the kernel of our product to manage TLB efficiently.

> cheers,
> grant

Thank you very much, Grant.

Cho KyongHo.

Re: [PATCH v7 00/12] iommu/exynos: Fixes and Enhancements of System MMU driver with DT

[Antonios Motakis]

Hello Cho,

I have been trying out the Exynos System MMU driver including your
fixes, however I notice that if you try to get the iommu_group of a
device (i.e. iommu_group_get(&pdev->dev)) this will not work. Since
each device is behind its own System MMU I would expect a distinct
iommu_group for that device, instead I get NULL (I tried this with the
MFC).

Indeed, it looks like this is not currently implemented in the driver.
Is this something that is on the roadmap?

Best regards,
Antonios Motakis

On Fri, Jul 5, 2013 at 2:29 PM, Cho KyongHo <pullip.cho@samsung.com> wrote:
> The current exynos-iommu(System MMU) driver does not work autonomously
> since it is lack of support for power management of peripheral blocks.
> For example, MFC device driver must ensure that its System MMU is disabled
> before MFC block is power-down not to invalidate IOTLB in the System MMU
> when I/O memory mapping is changed. Because A System MMU is resides in the
> same H/W block, access to control registers of System MMU while the H/W
> block is turned off must be prohibited.
>
> This set of changes solves the above problem with setting each System MMUs
> as the parent of the device which owns the System MMU to recieve the
> information when the device is turned off or turned on.
>
> Another big change to the driver is the support for devicetree.
> The bindings for System MMU is described in
> Documentation/devicetree/bindings/arm/samsung/system-mmu.txt
>
> In addition, this patchset also includes several bug fixes and enhancements
> of the current driver.
>
> Change log:
> v7:
> - Rebased on the stable 3.10
> - Registered PM domains and gate clocks with DT
> - Changed connection method between a System MMU and its master H/W
>    'mmu-master' property in the node of System MMU
>    --> 'iommu' property in the node of master H/W
> - Marking device descriptor of master H/W of a System MMU with bus notifier.
> - Power management (PM_RUNTIME, PM_SLEEP) of System MMUs with gpd_dev_ops
>    of Generic IO Powerdomain. gpd_dev_ops are set to the master H/Ws
>    before they are probed in the bus notifier.
> - Removed additional debugging features like debugfs entries and
>    version names.
> - Removed support for advanced features of System MMU 3.2 and 3.3
>    the current IOMMU API cannot handle the feature
>   (A kind of L2 TLB that fetches several consequence page table entries.
>    It must be initialized by the driver of master H/W whenever it works.)
>
> v6:
> - Rebased on the branch, next/iommu-exynos of
>   git.kernel.org/pub/scm/linux/kernel/git/kgene/linux-samsung.git
>
> v5:
> - new bugfix: patch 01
> - Reordered patches
>   * patch 01 ~ 05: Bugfix and enhancements of the existing driver
>   * patch 06 ~ 10: Device Tree support and callbacks for power management
>   * patch 11     : System MMU 3.2 and 3.3 support
>   * patch 12 ~ 14: Debugging features
> - Additional code compaction
>
> v4:
> - Remove Change-Id from v3 patches
> - Change the order of the third and the first patch
>   Thanks to Kukjin Kim.
> - Fix memory leak when allocating and assigning exynos_iommu_owner to client
>   device if the client device has multiple System MMUs.
>   Thanks to Rahul Sharma.
>
> v3:
> - Fix prefetch buffer flag definition for System MMU 3.3 (patch 10/12)
> - Fix incorrect setting for SET_RUNTIME_PM_OPS (patch 09/12)
>   Thanks to Prathyush.
>
> v2:
> - Split the patch to iommu/exynos into 9 patches
> - Support for System MMU 3.3
> - Some code compaction
>
> Patch summary:
> [PATCH v7 1/9] iommu/exynos: do not include removed header
> [PATCH v7 2/9] iommu/exynos: add missing cache flush for removed page table entries
> [PATCH v7 3/9] iommu/exynos: fix page table maintenance
> [PATCH v7 4/9] iommu/exynos: allocate lv2 page table from own slab
> [PATCH v7 5/9] iommu/exynos: change rwlock to spinlock
> [PATCH v7 6/9] clk: exynos5250: add gate clock descriptions of System MMU
> [PATCH v7 7/9] ARM: dts: Add description of System MMU of Exynos SoCs
> [PATCH v7 8/9] iommu/exynos: support for device tree
> [PATCH v7 9/9] iommu/exynos: add bus notifier for registering System MMU
>
> Diffstats:
> .../devicetree/bindings/clock/exynos5250-clock.txt |   28 +-
> .../bindings/iommu/samsung,exynos4210-sysmmu.txt   |  103 ++
> arch/arm/boot/dts/exynos4.dtsi                     |  122 +++
> arch/arm/boot/dts/exynos4210.dtsi                  |   25 +
> arch/arm/boot/dts/exynos4x12.dtsi                  |   76 ++
> arch/arm/boot/dts/exynos5250.dtsi                  |  291 ++++++
> drivers/clk/samsung/clk-exynos5250.c               |   57 +-
> drivers/iommu/Kconfig                              |    5 +-
> drivers/iommu/exynos-iommu.c                       | 1011 +++++++++++++-------
> 9 files changed, 1382 insertions(+), 336 deletions(-)
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

RE: [PATCH v7 00/12] iommu/exynos: Fixes and Enhancements of System MMU driver with DT

[Cho KyongHo]

> -----Original Message-----
> From: Antonios Motakis [mailto:a.motakis@virtualopensystems.com]
> Sent: Friday, July 19, 2013 1:25 AM
> 
> Hello Cho,
> 
> I have been trying out the Exynos System MMU driver including your
> fixes, however I notice that if you try to get the iommu_group of a
> device (i.e. iommu_group_get(&pdev->dev)) this will not work. Since
> each device is behind its own System MMU I would expect a distinct
> iommu_group for that device, instead I get NULL (I tried this with the
> MFC).
> 
> Indeed, it looks like this is not currently implemented in the driver.
> Is this something that is on the roadmap?
> 

I have not implemented anything about iommu_group
since a System MMU is dedicated to a single master device.
I also did not find any reason to implement something about iommu_group.
I would like to know why you need to call iommu_group_get().
Do you need some information in user-space?

Thank you.

Cho KyongHo.

> Best regards,
> Antonios Motakis
> 
> On Fri, Jul 5, 2013 at 2:29 PM, Cho KyongHo <pullip.cho@samsung.com> wrote:
> > The current exynos-iommu(System MMU) driver does not work autonomously
> > since it is lack of support for power management of peripheral blocks.
> > For example, MFC device driver must ensure that its System MMU is disabled
> > before MFC block is power-down not to invalidate IOTLB in the System MMU
> > when I/O memory mapping is changed. Because A System MMU is resides in the
> > same H/W block, access to control registers of System MMU while the H/W
> > block is turned off must be prohibited.
> >
> > This set of changes solves the above problem with setting each System MMUs
> > as the parent of the device which owns the System MMU to recieve the
> > information when the device is turned off or turned on.
> >
> > Another big change to the driver is the support for devicetree.
> > The bindings for System MMU is described in
> > Documentation/devicetree/bindings/arm/samsung/system-mmu.txt
> >
> > In addition, this patchset also includes several bug fixes and enhancements
> > of the current driver.
> >
> > Change log:
> > v7:
> > - Rebased on the stable 3.10
> > - Registered PM domains and gate clocks with DT
> > - Changed connection method between a System MMU and its master H/W
> >    'mmu-master' property in the node of System MMU
> >    --> 'iommu' property in the node of master H/W
> > - Marking device descriptor of master H/W of a System MMU with bus notifier.
> > - Power management (PM_RUNTIME, PM_SLEEP) of System MMUs with gpd_dev_ops
> >    of Generic IO Powerdomain. gpd_dev_ops are set to the master H/Ws
> >    before they are probed in the bus notifier.
> > - Removed additional debugging features like debugfs entries and
> >    version names.
> > - Removed support for advanced features of System MMU 3.2 and 3.3
> >    the current IOMMU API cannot handle the feature
> >   (A kind of L2 TLB that fetches several consequence page table entries.
> >    It must be initialized by the driver of master H/W whenever it works.)
> >
> > v6:
> > - Rebased on the branch, next/iommu-exynos of
> >   git.kernel.org/pub/scm/linux/kernel/git/kgene/linux-samsung.git
> >
> > v5:
> > - new bugfix: patch 01
> > - Reordered patches
> >   * patch 01 ~ 05: Bugfix and enhancements of the existing driver
> >   * patch 06 ~ 10: Device Tree support and callbacks for power management
> >   * patch 11     : System MMU 3.2 and 3.3 support
> >   * patch 12 ~ 14: Debugging features
> > - Additional code compaction
> >
> > v4:
> > - Remove Change-Id from v3 patches
> > - Change the order of the third and the first patch
> >   Thanks to Kukjin Kim.
> > - Fix memory leak when allocating and assigning exynos_iommu_owner to client
> >   device if the client device has multiple System MMUs.
> >   Thanks to Rahul Sharma.
> >
> > v3:
> > - Fix prefetch buffer flag definition for System MMU 3.3 (patch 10/12)
> > - Fix incorrect setting for SET_RUNTIME_PM_OPS (patch 09/12)
> >   Thanks to Prathyush.
> >
> > v2:
> > - Split the patch to iommu/exynos into 9 patches
> > - Support for System MMU 3.3
> > - Some code compaction
> >
> > Patch summary:
> > [PATCH v7 1/9] iommu/exynos: do not include removed header
> > [PATCH v7 2/9] iommu/exynos: add missing cache flush for removed page table entries
> > [PATCH v7 3/9] iommu/exynos: fix page table maintenance
> > [PATCH v7 4/9] iommu/exynos: allocate lv2 page table from own slab
> > [PATCH v7 5/9] iommu/exynos: change rwlock to spinlock
> > [PATCH v7 6/9] clk: exynos5250: add gate clock descriptions of System MMU
> > [PATCH v7 7/9] ARM: dts: Add description of System MMU of Exynos SoCs
> > [PATCH v7 8/9] iommu/exynos: support for device tree
> > [PATCH v7 9/9] iommu/exynos: add bus notifier for registering System MMU
> >
> > Diffstats:
> > .../devicetree/bindings/clock/exynos5250-clock.txt |   28 +-
> > .../bindings/iommu/samsung,exynos4210-sysmmu.txt   |  103 ++
> > arch/arm/boot/dts/exynos4.dtsi                     |  122 +++
> > arch/arm/boot/dts/exynos4210.dtsi                  |   25 +
> > arch/arm/boot/dts/exynos4x12.dtsi                  |   76 ++
> > arch/arm/boot/dts/exynos5250.dtsi                  |  291 ++++++
> > drivers/clk/samsung/clk-exynos5250.c               |   57 +-
> > drivers/iommu/Kconfig                              |    5 +-
> > drivers/iommu/exynos-iommu.c                       | 1011 +++++++++++++-------
> > 9 files changed, 1382 insertions(+), 336 deletions(-)
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at  http://www.tux.org/lkml/