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Re: [RFC PATCH 4/6] iommu/arm-smmu: Add support for IOMMU_DOMAIN_DMA in SMMUv1/SMMUv2 driver

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  Re: [RFC PATCH 4/6] iommu/arm-smmu: Add support for IOMMU_DOMAIN_DMA  in SMMUv1/SMMUv2 driver Robin Murphy <robin.murphy@arm.com> - 2016-01-28 18:30 +0100
    Re: [RFC PATCH 4/6] iommu/arm-smmu: Add support for IOMMU_DOMAIN_DMA  in SMMUv1/SMMUv2 driver Mark Rutland <mark.rutland@arm.com> - 2016-01-28 18:50 +0100
    RE: [RFC PATCH 4/6] iommu/arm-smmu: Add support for  IOMMU_DOMAIN_DMA in SMMUv1/SMMUv2 driver Anup Patel <anup.patel@broadcom.com> - 2016-01-29 05:00 +0100

#1320903 — Re: [RFC PATCH 4/6] iommu/arm-smmu: Add support for IOMMU_DOMAIN_DMA in SMMUv1/SMMUv2 driver

On 27/01/16 05:21, Anup Patel wrote:
> To allow use of large memory (> 4Gb) with 32bit devices we need to use
> some kind of iommu for such 32bit devices.
>
> This patch extends SMMUv1/SMMUv2 driver to support DMA domains which
> in-turn will allows us to use iommu based DMA mappings for 32bit devices.
>
> Signed-off-by: Anup Patel <anup.patel@broadcom.com>
> Reviewed-by: Ray Jui <rjui@broadcom.com>
> Reviewed-by: Scott Branden <sbranden@broadcom.com>
> ---
>   drivers/iommu/arm-smmu.c | 21 ++++++++++++++++++++-
>   1 file changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index 9bdf6b2..43424fe 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -29,6 +29,7 @@
>   #define pr_fmt(fmt) "arm-smmu: " fmt
>
>   #include <linux/delay.h>
> +#include <linux/dma-iommu.h>
>   #include <linux/dma-mapping.h>
>   #include <linux/err.h>
>   #include <linux/interrupt.h>
> @@ -967,7 +968,7 @@ static struct iommu_domain *arm_smmu_domain_alloc(unsigned type)
>   {
>   	struct arm_smmu_domain *smmu_domain;
>
> -	if (type != IOMMU_DOMAIN_UNMANAGED)
> +	if (type != IOMMU_DOMAIN_UNMANAGED && type != IOMMU_DOMAIN_DMA)
>   		return NULL;
>   	/*
>   	 * Allocate the domain and initialise some of its data structures.
> @@ -978,6 +979,12 @@ static struct iommu_domain *arm_smmu_domain_alloc(unsigned type)
>   	if (!smmu_domain)
>   		return NULL;
>
> +	if (type == IOMMU_DOMAIN_DMA &&
> +	    iommu_get_dma_cookie(&smmu_domain->domain)) {
> +		kfree(smmu_domain);
> +		return NULL;
> +	}
> +
>   	mutex_init(&smmu_domain->init_mutex);
>   	spin_lock_init(&smmu_domain->pgtbl_lock);
>
> @@ -992,6 +999,7 @@ static void arm_smmu_domain_free(struct iommu_domain *domain)
>   	 * Free the domain resources. We assume that all devices have
>   	 * already been detached.
>   	 */
> +	iommu_put_dma_cookie(domain);
>   	arm_smmu_destroy_domain_context(domain);
>   	kfree(smmu_domain);
>   }
> @@ -1361,6 +1369,16 @@ static int arm_smmu_init_platform_device(struct device *dev,
>   	return 0;
>   }
>
> +int arm_smmu_of_xlate(struct device *dev, struct of_phandle_args *args)
> +{
> +	/*
> +	 * Nothing to do here because SMMU is already aware of all
> +	 * MMU masters and their stream IDs using mmu-master attibute
> +	 * SMMU DT node.
> +	 */

...but on the same hand this will also never get called if there's no 
"iommus" property on the master. Maintaining support for existing users 
of the "mmu-masters" binding is one thing (namely the thing that's been 
slowing down my efforts to clean up the really hacky generic binding 
support I did all the DMA stuff with), but having _both_ bindings in a 
single DT is something I don't think anybody wants to see - is that how 
you've tested this?

Robin.

> +	return 0;
> +}
> +
>   static int arm_smmu_add_device(struct device *dev)
>   {
>   	struct iommu_group *group;
> @@ -1458,6 +1476,7 @@ static struct iommu_ops arm_smmu_ops = {
>   	.unmap			= arm_smmu_unmap,
>   	.map_sg			= default_iommu_map_sg,
>   	.iova_to_phys		= arm_smmu_iova_to_phys,
> +	.of_xlate		= arm_smmu_of_xlate,
>   	.add_device		= arm_smmu_add_device,
>   	.remove_device		= arm_smmu_remove_device,
>   	.device_group		= arm_smmu_device_group,
>

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#1320921

On Thu, Jan 28, 2016 at 05:28:30PM +0000, Robin Murphy wrote:
> On 27/01/16 05:21, Anup Patel wrote:
> >To allow use of large memory (> 4Gb) with 32bit devices we need to use
> >some kind of iommu for such 32bit devices.
> >
> >This patch extends SMMUv1/SMMUv2 driver to support DMA domains which
> >in-turn will allows us to use iommu based DMA mappings for 32bit devices.
> >
> >Signed-off-by: Anup Patel <anup.patel@broadcom.com>
> >Reviewed-by: Ray Jui <rjui@broadcom.com>
> >Reviewed-by: Scott Branden <sbranden@broadcom.com>
> >---
> >  drivers/iommu/arm-smmu.c | 21 ++++++++++++++++++++-
> >  1 file changed, 20 insertions(+), 1 deletion(-)
> >
> >diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> >index 9bdf6b2..43424fe 100644
> >--- a/drivers/iommu/arm-smmu.c
> >+++ b/drivers/iommu/arm-smmu.c
> >@@ -29,6 +29,7 @@
> >  #define pr_fmt(fmt) "arm-smmu: " fmt
> >
> >  #include <linux/delay.h>
> >+#include <linux/dma-iommu.h>
> >  #include <linux/dma-mapping.h>
> >  #include <linux/err.h>
> >  #include <linux/interrupt.h>
> >@@ -967,7 +968,7 @@ static struct iommu_domain *arm_smmu_domain_alloc(unsigned type)
> >  {
> >  	struct arm_smmu_domain *smmu_domain;
> >
> >-	if (type != IOMMU_DOMAIN_UNMANAGED)
> >+	if (type != IOMMU_DOMAIN_UNMANAGED && type != IOMMU_DOMAIN_DMA)
> >  		return NULL;
> >  	/*
> >  	 * Allocate the domain and initialise some of its data structures.
> >@@ -978,6 +979,12 @@ static struct iommu_domain *arm_smmu_domain_alloc(unsigned type)
> >  	if (!smmu_domain)
> >  		return NULL;
> >
> >+	if (type == IOMMU_DOMAIN_DMA &&
> >+	    iommu_get_dma_cookie(&smmu_domain->domain)) {
> >+		kfree(smmu_domain);
> >+		return NULL;
> >+	}
> >+
> >  	mutex_init(&smmu_domain->init_mutex);
> >  	spin_lock_init(&smmu_domain->pgtbl_lock);
> >
> >@@ -992,6 +999,7 @@ static void arm_smmu_domain_free(struct iommu_domain *domain)
> >  	 * Free the domain resources. We assume that all devices have
> >  	 * already been detached.
> >  	 */
> >+	iommu_put_dma_cookie(domain);
> >  	arm_smmu_destroy_domain_context(domain);
> >  	kfree(smmu_domain);
> >  }
> >@@ -1361,6 +1369,16 @@ static int arm_smmu_init_platform_device(struct device *dev,
> >  	return 0;
> >  }
> >
> >+int arm_smmu_of_xlate(struct device *dev, struct of_phandle_args *args)
> >+{
> >+	/*
> >+	 * Nothing to do here because SMMU is already aware of all
> >+	 * MMU masters and their stream IDs using mmu-master attibute
> >+	 * SMMU DT node.
> >+	 */
> 
> ...but on the same hand this will also never get called if there's
> no "iommus" property on the master. Maintaining support for existing
> users of the "mmu-masters" binding is one thing (namely the thing
> that's been slowing down my efforts to clean up the really hacky
> generic binding support I did all the DMA stuff with), but having
> _both_ bindings in a single DT is something I don't think anybody
> wants to see

Indeed. NAK to the mixed case.

Mark.

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#1321472 — RE: [RFC PATCH 4/6] iommu/arm-smmu: Add support for IOMMU_DOMAIN_DMA in SMMUv1/SMMUv2 driver

> -----Original Message-----
> From: Robin Murphy [mailto:robin.murphy@arm.com]
> Sent: 28 January 2016 22:59
> To: Anup Patel; Catalin Marinas; Joerg Roedel; Will Deacon; Sricharan R; Linux
> IOMMU; Linux ARM Kernel
> Cc: Rob Herring; Pawel Moll; Mark Rutland; Ian Campbell; Kumar Gala; Device
> Tree; Ray Jui; Scott Branden; Vikram Prakash; Linux Kernel; bcm-kernel-
> feedback-list
> Subject: Re: [RFC PATCH 4/6] iommu/arm-smmu: Add support for
> IOMMU_DOMAIN_DMA in SMMUv1/SMMUv2 driver
> 
> On 27/01/16 05:21, Anup Patel wrote:
> > To allow use of large memory (> 4Gb) with 32bit devices we need to use
> > some kind of iommu for such 32bit devices.
> >
> > This patch extends SMMUv1/SMMUv2 driver to support DMA domains which
> > in-turn will allows us to use iommu based DMA mappings for 32bit devices.
> >
> > Signed-off-by: Anup Patel <anup.patel@broadcom.com>
> > Reviewed-by: Ray Jui <rjui@broadcom.com>
> > Reviewed-by: Scott Branden <sbranden@broadcom.com>
> > ---
> >   drivers/iommu/arm-smmu.c | 21 ++++++++++++++++++++-
> >   1 file changed, 20 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c index
> > 9bdf6b2..43424fe 100644
> > --- a/drivers/iommu/arm-smmu.c
> > +++ b/drivers/iommu/arm-smmu.c
> > @@ -29,6 +29,7 @@
> >   #define pr_fmt(fmt) "arm-smmu: " fmt
> >
> >   #include <linux/delay.h>
> > +#include <linux/dma-iommu.h>
> >   #include <linux/dma-mapping.h>
> >   #include <linux/err.h>
> >   #include <linux/interrupt.h>
> > @@ -967,7 +968,7 @@ static struct iommu_domain
> *arm_smmu_domain_alloc(unsigned type)
> >   {
> >   	struct arm_smmu_domain *smmu_domain;
> >
> > -	if (type != IOMMU_DOMAIN_UNMANAGED)
> > +	if (type != IOMMU_DOMAIN_UNMANAGED && type !=
> IOMMU_DOMAIN_DMA)
> >   		return NULL;
> >   	/*
> >   	 * Allocate the domain and initialise some of its data structures.
> > @@ -978,6 +979,12 @@ static struct iommu_domain
> *arm_smmu_domain_alloc(unsigned type)
> >   	if (!smmu_domain)
> >   		return NULL;
> >
> > +	if (type == IOMMU_DOMAIN_DMA &&
> > +	    iommu_get_dma_cookie(&smmu_domain->domain)) {
> > +		kfree(smmu_domain);
> > +		return NULL;
> > +	}
> > +
> >   	mutex_init(&smmu_domain->init_mutex);
> >   	spin_lock_init(&smmu_domain->pgtbl_lock);
> >
> > @@ -992,6 +999,7 @@ static void arm_smmu_domain_free(struct
> iommu_domain *domain)
> >   	 * Free the domain resources. We assume that all devices have
> >   	 * already been detached.
> >   	 */
> > +	iommu_put_dma_cookie(domain);
> >   	arm_smmu_destroy_domain_context(domain);
> >   	kfree(smmu_domain);
> >   }
> > @@ -1361,6 +1369,16 @@ static int arm_smmu_init_platform_device(struct
> device *dev,
> >   	return 0;
> >   }
> >
> > +int arm_smmu_of_xlate(struct device *dev, struct of_phandle_args
> > +*args) {
> > +	/*
> > +	 * Nothing to do here because SMMU is already aware of all
> > +	 * MMU masters and their stream IDs using mmu-master attibute
> > +	 * SMMU DT node.
> > +	 */
> 
> ...but on the same hand this will also never get called if there's no "iommus"
> property on the master. Maintaining support for existing users of the "mmu-
> masters" binding is one thing (namely the thing that's been slowing down my
> efforts to clean up the really hacky generic binding support I did all the DMA
> stuff with), but having _both_ bindings in a single DT is something I don't think
> anybody wants to see - is that how you've tested this?

We want to use iommu aware DMA mapping APIs for certain 32bit devices
in our SoC without changing device driver of these 32bit devices
(such as PL330). Currently, to this we have to specifiy "iommus" attribute in
32bit device DT node. If we specify  "iommus" attribute in device DT node then
of_iommu_configure() expects "of_xlate" callback and it will fail if this
callback is not available.

If there is a way use DMA mappings APIs for 32bit devices without having
"of_xlate" in SMMU driver then I would prefer that approach. Suggestions??

> 
> Robin.
> 
> > +	return 0;
> > +}
> > +
> >   static int arm_smmu_add_device(struct device *dev)
> >   {
> >   	struct iommu_group *group;
> > @@ -1458,6 +1476,7 @@ static struct iommu_ops arm_smmu_ops = {
> >   	.unmap			= arm_smmu_unmap,
> >   	.map_sg			= default_iommu_map_sg,
> >   	.iova_to_phys		= arm_smmu_iova_to_phys,
> > +	.of_xlate		= arm_smmu_of_xlate,
> >   	.add_device		= arm_smmu_add_device,
> >   	.remove_device		= arm_smmu_remove_device,
> >   	.device_group		= arm_smmu_device_group,
> >
> 

Regards,
Anup

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