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Message-ID: <570E241D.9000902@semihalf.com>
Date: Wed, 13 Apr 2016 12:49:01 +0200
From: Tomasz Nowicki <tn@...ihalf.com>
To: Marc Zyngier <marc.zyngier@....com>, tglx@...utronix.de,
jason@...edaemon.net, rjw@...ysocki.net, lorenzo.pieralisi@....com,
robert.richter@...iumnetworks.com, shijie.huang@....com,
Suravee.Suthikulpanit@....com, hanjun.guo@...aro.org
Cc: al.stone@...aro.org, mw@...ihalf.com, graeme.gregory@...aro.org,
Catalin.Marinas@....com, will.deacon@....com,
linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, ddaney.cavm@...il.com,
okaya@...eaurora.org
Subject: Re: [PATCH V4 1/7] acpi, pci: Setup MSI domain on a per-devices
basis.
On 13.04.2016 12:18, Marc Zyngier wrote:
> On 04/04/16 09:52, Tomasz Nowicki wrote:
>> It is now possible to provide information about which MSI controller to
>> use on a per-device basis for DT. This patch supply this with ACPI support.
>>
>> In order to handle MSI domain on per-devices basis we need to add
>> PCI device requester ID (RID) mapper, MSI domain provider and corresponding
>> registration:
>> pci_acpi_msi_domain_get_msi_rid - maps PCI ID and returns MSI RID
>> pci_acpi_register_msi_rid_mapper - registers RID mapper
>>
>> pci_acpi_msi_get_device_domain - finds PCI device MSI domain
>> pci_acpi_register_dev_msi_fwnode_provider - registers MSI domain finder
>>
>> Then, it is plugged into MSI infrastructure.
>>
>> To: Bjorn Helgaas <bhelgaas@...gle.com>
>> To: Rafael J. Wysocki <rjw@...ysocki.net>
>> Signed-off-by: Tomasz Nowicki <tn@...ihalf.com>
>> ---
>> drivers/pci/msi.c | 10 +++++--
>> drivers/pci/pci-acpi.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++
>> include/linux/pci.h | 11 ++++++++
>> 3 files changed, 95 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
>> index a080f44..07b59a3 100644
>> --- a/drivers/pci/msi.c
>> +++ b/drivers/pci/msi.c
>> @@ -1364,8 +1364,8 @@ u32 pci_msi_domain_get_msi_rid(struct irq_domain *domain, struct pci_dev *pdev)
>> pci_for_each_dma_alias(pdev, get_msi_id_cb, &rid);
>>
>> of_node = irq_domain_get_of_node(domain);
>> - if (of_node)
>> - rid = of_msi_map_rid(&pdev->dev, of_node, rid);
>> + rid = of_node ? of_msi_map_rid(&pdev->dev, of_node, rid) :
>> + pci_acpi_msi_domain_get_msi_rid(pdev, rid);
>>
>> return rid;
>> }
>> @@ -1381,9 +1381,13 @@ u32 pci_msi_domain_get_msi_rid(struct irq_domain *domain, struct pci_dev *pdev)
>> */
>> struct irq_domain *pci_msi_get_device_domain(struct pci_dev *pdev)
>> {
>> + struct irq_domain *dom;
>> u32 rid = 0;
>>
>> pci_for_each_dma_alias(pdev, get_msi_id_cb, &rid);
>> - return of_msi_map_get_device_domain(&pdev->dev, rid);
>> + dom = of_msi_map_get_device_domain(&pdev->dev, rid);
>> + if (!dom)
>> + dom = pci_acpi_msi_get_device_domain(pdev, rid);
>> + return dom;
>> }
>> #endif /* CONFIG_PCI_MSI_IRQ_DOMAIN */
>> diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
>> index 9a033e8..26f4552 100644
>> --- a/drivers/pci/pci-acpi.c
>> +++ b/drivers/pci/pci-acpi.c
>> @@ -731,6 +731,83 @@ struct irq_domain *pci_host_bridge_acpi_msi_domain(struct pci_bus *bus)
>> return irq_find_matching_fwnode(fwnode, DOMAIN_BUS_PCI_MSI);
>> }
>>
>> +static u32 (*pci_msi_map_dev_rid_cb)(struct pci_dev *pdev, u32 req_id);
>> +
>> +/**
>> + * pci_acpi_register_msi_rid_mapper - Register callback to map the MSI
>> + * requester id (RID)
>> + * @fn: Callback mapping a PCI device RID.
>> + *
>> + * This should be called by irqchip driver, which can provide firmware-defined
>> + * topologies about MSI requester id (RID) on a per-device basis.
>> + */
>> +void pci_acpi_register_msi_rid_mapper(u32 (*fn)(struct pci_dev *, u32))
>> +{
>> + pci_msi_map_dev_rid_cb = fn;
>> +}
>> +
>> +/**
>> + * pci_acpi_msi_domain_get_msi_rid - Get the MSI requester id (RID) of
>> + * a PCI device
>> + * @pdev: The PCI device.
>> + * @rid_in: The PCI device request ID.
>> + *
>> + * This function uses the callback function registered by
>> + * pci_acpi_register_msi_rid_mapper() to get the device RID based on ACPI
>> + * supplied mapping.
>> + * This should return rid_in on error or when there is no valid map.
>> + */
>> +u32 pci_acpi_msi_domain_get_msi_rid(struct pci_dev *pdev, u32 rid_in)
>> +{
>> + if (!pci_msi_map_dev_rid_cb)
>> + return rid_in;
>> +
>> + return pci_msi_map_dev_rid_cb(pdev, rid_in);
>> +}
>> +
>> +static struct fwnode_handle *(*pci_msi_get_dev_fwnode_cb)(struct pci_dev *pdev,
>> + u32 req_id);
>> +
>> +/**
>> + * pci_acpi_register_dev_msi_fwnode_provider - Register callback to retrieve
>> + * domain fwnode on the per-device basis
>> + * @fn: Callback matching a device to a fwnode that identifies a PCI
>> + * MSI domain.
>> + *
>> + * This should be called by irqchip driver, which can provide firmware-defined
>> + * topologies about which MSI controller to use on a per-device basis.
>> + */
>> +void
>> +pci_acpi_register_dev_msi_fwnode_provider(
>> + struct fwnode_handle *(*fn)(struct pci_dev *, u32))
>> +{
>> + pci_msi_get_dev_fwnode_cb = fn;
>> +}
>
> I'm quite sceptical about this indirection. Either IORT is the only
> mapping infrastructure that we can use for ACPI and we can then directly
> call into it, or we can have several of them (which ones?) and we need
> more than just this single slot.
>
> So in any case, I don't think this is the right solution. As my
> understanding is that IORT is the only source of RID remapping, we
> should be able to directly call into the IORT code without this complexity.
>
Thanks Marc. I am not aware of any other RID remapper too. I will drop
this layer and call IORT directly.
Tomasz
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