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Date: Fri, 30 Nov 2012 12:59:32 +0800
From: Mark Zhang <nvmarkzhang@...il.com>
To: Hiroshi Doyu <hdoyu@...dia.com>
CC: "m.szyprowski@...sung.com" <m.szyprowski@...sung.com>,
"swarren@...dotorg.org" <swarren@...dotorg.org>,
"joro@...tes.org" <joro@...tes.org>,
"James.Bottomley@...senPartnership.com"
<James.Bottomley@...senPartnership.com>,
"arnd@...db.de" <arnd@...db.de>, Krishna Reddy <vdumpa@...dia.com>,
"linux@....linux.org.uk" <linux@....linux.org.uk>,
"minchan@...nel.org" <minchan@...nel.org>,
"chunsang.jeong@...aro.org" <chunsang.jeong@...aro.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"subashrp@...il.com" <subashrp@...il.com>,
"linaro-mm-sig@...ts.linaro.org" <linaro-mm-sig@...ts.linaro.org>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
"kyungmin.park@...sung.com" <kyungmin.park@...sung.com>,
"pullip.cho@...sung.com" <pullip.cho@...sung.com>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 1/1] ARM: tegra: bus_notifier registers IOMMU devices(was:
How to specify IOMMU'able devices in DT)
On 11/28/2012 09:48 PM, Hiroshi Doyu wrote:
> Hiroshi Doyu <hdoyu@...dia.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@...dia.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@...dia.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.
And finally we see this patch, that's great. :)
> + dev_err(dev, "Failed to attach %s\n", dev_name(dev));
> + dev_dbg(dev, "Attached %s to map %p\n", dev_name(dev), map);
> + break;
> + }
> + return NOTIFY_DONE;
> +}
> +#else
> +#define tegra_iommu_device_notifier NULL
> +#endif
> +
> +static struct notifier_block tegra_iommu_device_nb = {
> + .notifier_call = tegra_iommu_device_notifier,
> +};
> +
> static void __init tegra30_dt_init(void)
> {
> tegra_clk_init_from_table(tegra_dt_clk_init_table);
>
> + if (IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU))
> + bus_register_notifier(&platform_bus_type,
> + &tegra_iommu_device_nb);
> +
> of_platform_populate(NULL, of_default_bus_match_table,
> tegra30_auxdata_lookup, NULL);
> }
>
--
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