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pci smmu parse in acpi

-v0.1 2016.12.23 init Sherlock

This document shares a code analysis based on Linux-v4.9 about how to parse SMMU

1. acpi smmu parse

acpi_init    --> acpi_iort_init            /* parse the SMMU node in IORT table */        --> iort_init_platform_devices                /* create a platform_device for SMMU, and add it to platform_bus */            --> iort_add_smmu_platform_device                    /* why call this function here? */                --> acpi_dma_configure                    --> iort_iommu_configure            /* call functions in section: __iort_acpi_probe_table ~ __iort_acpi_probe_table_end */        --> acpi_probe_device_table(iort)

2. put arm_smmu_init in above section in compile phase

IORT_ACPI_DECLARE(arm_smmu_v3, ACPI_SIG_IORT, acpi_smmu_v3_init);arm_smmu_v3_init         /*         * add SMMU driver to platform_bus, this will trigger probe function to         * bind this driver and above SMMU platform_device.         */    --> platform_driver_register(&arm_smmu_driver)

3. PCIe device get its SMMU device

pci_device_add    --> pci_dma_configure(dev)        --> acpi_dma_configure(&dev->dev, attr)acpi_dma_configure       /* if dev is a pci device, first find related RC node in IORT table */    -->iommu = iort_iommu_configure             /* RC node */        --> node = iort_scan_node                /* parent here is SMMU node */            --> parent = iort_node_map_rid

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