linux/drivers/acpi/viot.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Virtual I/O topology
 *
 * The Virtual I/O Translation Table (VIOT) describes the topology of
 * para-virtual IOMMUs and the endpoints they manage. The OS uses it to
 * initialize devices in the right order, preventing endpoints from issuing DMA
 * before their IOMMU is ready.
 *
 * When binding a driver to a device, before calling the device driver's probe()
 * method, the driver infrastructure calls dma_configure(). At that point the
 * VIOT driver looks for an IOMMU associated to the device in the VIOT table.
 * If an IOMMU exists and has been initialized, the VIOT driver initializes the
 * device's IOMMU fwspec, allowing the DMA infrastructure to invoke the IOMMU
 * ops when the device driver configures DMA mappings. If an IOMMU exists and
 * hasn't yet been initialized, VIOT returns -EPROBE_DEFER to postpone probing
 * the device until the IOMMU is available.
 */
#define pr_fmt(fmt) …

#include <linux/acpi_viot.h>
#include <linux/fwnode.h>
#include <linux/iommu.h>
#include <linux/list.h>
#include <linux/pci.h>
#include <linux/platform_device.h>

struct viot_iommu { … };

struct viot_endpoint { … };

static struct acpi_table_viot *viot;
static LIST_HEAD(viot_iommus);
static LIST_HEAD(viot_pci_ranges);
static LIST_HEAD(viot_mmio_endpoints);

static int __init viot_check_bounds(const struct acpi_viot_header *hdr)
{ … }

static int __init viot_get_pci_iommu_fwnode(struct viot_iommu *viommu,
					    u16 segment, u16 bdf)
{ … }

static int __init viot_get_mmio_iommu_fwnode(struct viot_iommu *viommu,
					     u64 address)
{ … }

static struct viot_iommu * __init viot_get_iommu(unsigned int offset)
{ … }

static int __init viot_parse_node(const struct acpi_viot_header *hdr)
{ … }

/**
 * acpi_viot_early_init - Test the presence of VIOT and enable ACS
 *
 * If the VIOT does exist, ACS must be enabled. This cannot be
 * done in acpi_viot_init() which is called after the bus scan
 */
void __init acpi_viot_early_init(void)
{ … }

/**
 * acpi_viot_init - Parse the VIOT table
 *
 * Parse the VIOT table, prepare the list of endpoints to be used during DMA
 * setup of devices.
 */
void __init acpi_viot_init(void)
{ … }

static int viot_dev_iommu_init(struct device *dev, struct viot_iommu *viommu,
			       u32 epid)
{ … }

static int viot_pci_dev_iommu_init(struct pci_dev *pdev, u16 dev_id, void *data)
{ … }

static int viot_mmio_dev_iommu_init(struct platform_device *pdev)
{ … }

/**
 * viot_iommu_configure - Setup IOMMU ops for an endpoint described by VIOT
 * @dev: the endpoint
 *
 * Return: 0 on success, <0 on failure
 */
int viot_iommu_configure(struct device *dev)
{ … }