linux-kernel - Re: [RFC PATCH 09/11] drivers: acpi: implement acpi_dma

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Message-ID: <573B0F53.109@semihalf.com>
Date:	Tue, 17 May 2016 14:32:19 +0200
From:	Tomasz Nowicki <tn@...ihalf.com>
To:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	iommu@...ts.linux-foundation.org
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>,
	Robin Murphy <robin.murphy@....com>,
	Joerg Roedel <joro@...tes.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Will Deacon <will.deacon@....com>,
	Marc Zyngier <marc.zyngier@....com>,
	Hanjun Guo <hanjun.guo@...aro.org>,
	Jon Masters <jcm@...hat.com>,
	Sinan Kaya <okaya@...eaurora.org>, linux-acpi@...r.kernel.org,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC PATCH 09/11] drivers: acpi: implement acpi_dma_configure



On 17.05.2016 10:07, Tomasz Nowicki wrote:
> Hi Lorenzo,
>
> On 14.04.2016 19:25, Lorenzo Pieralisi wrote:
>> On DT based systems, the of_dma_configure() API implements DMA
>> configuration
>> for a given device. On ACPI systems an API equivalent to
>> of_dma_configure()
>> is missing which implies that it is currently not possible to set-up DMA
>> operations for devices through the ACPI generic kernel layer.
>>
>> This patch fills the gap by introducing acpi_dma_configure/deconfigure()
>> calls, that carry out IOMMU configuration through IORT (on systems where
>> it is present) and call arch_setup_dma_ops(...) with the retrieved
>> parameters.
>>
>> The DMA range size passed to arch_setup_dma_ops() is sized according
>> to the device coherent_dma_mask (starting at address 0x0), mirroring the
>> DT probing path behaviour when a dma-ranges property is not provided
>> for the device being probed; this changes the current
>> arch_setup_dma_ops()
>> call parameters in the ACPI probing case, but since arch_setup_dma_ops()
>> is a NOP on all architectures but ARM/ARM64 this patch does not change
>> the current kernel behaviour on them.
>>
>> This patch updates ACPI and PCI core code to use the newly introduced
>> acpi_dma_configure function, providing the same functionality
>> as of_dma_configure on ARM systems and leaving behaviour unchanged
>> for all other arches.
>>
>> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
>> Cc: Bjorn Helgaas <bhelgaas@...gle.com>
>> Cc: Robin Murphy <robin.murphy@....com>
>> Cc: Tomasz Nowicki <tn@...ihalf.com>
>> Cc: Joerg Roedel <joro@...tes.org>
>> Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
>> ---
>>   drivers/acpi/glue.c     |  4 +--
>>   drivers/acpi/iort.c     | 85
>> +++++++++++++++++++++++++++++++++++++++++++++++++
>>   drivers/acpi/scan.c     | 29 +++++++++++++++++
>>   drivers/pci/probe.c     |  3 +-
>>   include/acpi/acpi_bus.h |  2 ++
>>   include/linux/acpi.h    |  5 +++
>>   include/linux/iort.h    |  9 ++++++
>>   7 files changed, 133 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c
>> index 5ea5dc2..f8d6564 100644
>> --- a/drivers/acpi/glue.c
>> +++ b/drivers/acpi/glue.c
>> @@ -227,8 +227,7 @@ int acpi_bind_one(struct device *dev, struct
>> acpi_device *acpi_dev)
>>
>>       attr = acpi_get_dma_attr(acpi_dev);
>>       if (attr != DEV_DMA_NOT_SUPPORTED)
>> -        arch_setup_dma_ops(dev, 0, 0, NULL,
>> -                   attr == DEV_DMA_COHERENT);
>> +        acpi_dma_configure(dev, attr);
>>
>>       acpi_physnode_link_name(physical_node_name, node_id);
>>       retval = sysfs_create_link(&acpi_dev->dev.kobj, &dev->kobj,
>> @@ -251,6 +250,7 @@ int acpi_bind_one(struct device *dev, struct
>> acpi_device *acpi_dev)
>>       return 0;
>>
>>    err:
>> +    acpi_dma_deconfigure(dev);
>>       ACPI_COMPANION_SET(dev, NULL);
>>       put_device(dev);
>>       put_device(&acpi_dev->dev);
>> diff --git a/drivers/acpi/iort.c b/drivers/acpi/iort.c
>> index 2b5ce65..b1bb8fb 100644
>> --- a/drivers/acpi/iort.c
>> +++ b/drivers/acpi/iort.c
>> @@ -72,6 +72,31 @@ int iort_iommu_set_node(struct iommu_ops *ops,
>> struct acpi_iort_node *node,
>>       return 0;
>>   }
>>
>> +/**
>> + * iort_iommu_get_node - Retrieve iort_iommu_node associated with an
>> IORT node.
>> + *
>> + * @node: IORT table node to be looked-up
>> + *
>> + * Returns: iort_iommu_node pointer on success
>> + *          NULL on failure
>> + */
>> +static struct iort_iommu_node *iort_iommu_get_node(struct
>> acpi_iort_node *node)
>> +{
>> +    struct iort_iommu_node *iommu_node;
>> +
>> +    spin_lock(&iort_iommu_lock);
>> +    list_for_each_entry(iommu_node, &iort_iommu_list, list) {
>> +        if (iommu_node->node == node)
>> +            goto found;
>> +    }
>> +
>> +    iommu_node = NULL;
>> +found:
>> +    spin_unlock(&iort_iommu_lock);
>> +
>> +    return iommu_node;
>> +}
>> +
>>   typedef acpi_status (*iort_find_node_callback)
>>       (struct acpi_iort_node *node, void *context);
>>
>> @@ -405,6 +430,66 @@ iort_pci_get_domain(struct pci_dev *pdev, u32
>> req_id)
>>       return domain_handle;
>>   }
>>
>> +static int __get_pci_rid(struct pci_dev *pdev, u16 alias, void *data)
>> +{
>> +    u32 *rid = data;
>> +
>> +    *rid = alias;
>> +    return 0;
>> +}
>> +
>> +/**
>> + * iort_iommu_configure - Set-up IOMMU configuration for a device.
>> + *
>> + * @dev: device that requires IOMMU set-up
>> + *
>> + * Returns: iommu_ops pointer on configuration success
>> + *          NULL on configuration failure
>> + */
>> +struct iommu_ops *iort_iommu_configure(struct device *dev)
>> +{
>> +    struct acpi_iort_node *node, *parent;
>> +    struct iommu_ops *ops = NULL;
>> +    struct iommu_fwspec fwspec;
>> +    struct iort_iommu_node *iommu_node;
>> +    u32 rid = 0, devid = 0;
>> +
>> +    if (dev_is_pci(dev)) {
>> +        struct pci_bus *bus = to_pci_dev(dev)->bus;
>> +
>> +        pci_for_each_dma_alias(to_pci_dev(dev), __get_pci_rid,
>> +                       &rid);
>> +
>> +        node = iort_scan_node(ACPI_IORT_NODE_PCI_ROOT_COMPLEX,
>> +                      iort_find_dev_callback, &bus->dev);
>> +    } else
>> +        node = iort_scan_node(ACPI_IORT_NODE_NAMED_COMPONENT,
>> +                      iort_find_dev_callback, dev);
>
> I think this will not work for finding host bridge stream ID. We still
> need to use ACPI_IORT_NODE_PCI_ROOT_COMPLEX but 'dev' is not PCI device,
> right?

After private conversation, I think this part is OK.

Thanks,
Tomasz