zircon/vdso/msi.fidl

// Copyright 2020 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
library zx;

@transport("Syscall")
closed protocol Msi {
    /// ## Summary
    ///
    /// Allocate Message-Signaled Interrupts (MSIs).
    ///
    /// ## Declaration
    ///
    /// ```c
    /// #include <zircon/syscalls.h>
    ///
    /// zx_status_t zx_msi_allocate(zx_handle_t handle,
    ///                             uint32_t count,
    ///                             zx_handle_t* out_allocation);
    /// ```
    ///
    /// ## Description
    ///
    /// `zx_msi_allocate()` allocates a contiguous block of *count* MSIs and returns an
    /// MSI allocation object in *out_allocation* for use with [`zx_msi_create()`].
    /// This serves to allow a PCI device to request pre-allocation of MSI resources
    /// for use in creating Interrupt objects corresponding to the device's interrupts.
    /// The MSI allocation object is freed when *handle* is closed and no outstanding
    /// handles to Interrupt objects created by [`zx_msi_create()`] exist.
    ///
    /// *count* must be 1, 2, 4, 8, 16, or 32.
    ///
    /// *handle* must be a handle to the Root Resource, as such this syscall is
    /// intended for use only by the platform bus and Zircon coretests.
    ///
    /// ## Rights
    ///
    /// *handle* must have resource kind `ZX_RSRC_KIND_SYSTEM` and resource base
    /// `ZX_RSRC_SYSTEM_MSI_BASE`.
    ///
    /// ## Return value
    ///
    /// `zx_msi_allocate()` returns `ZX_OK` on success. In the event of failure, a
    /// negative error value is returned.
    ///
    /// ## Errors
    ///
    /// `ZX_ERR_INVALID_ARGS` *count* is not a valid value.
    ///
    /// `ZX_ERR_ACCESS_DENIED` *handle* is not a Root Resource handle.
    ///
    /// `ZX_ERR_NOT_SUPPORTED` MSIs are not supported by the platform.
    ///
    /// ## See also
    ///
    ///  - [`zx_msi_create()`]
    ///
    /// [`zx_msi_create()`]: msi_create.md
    strict Allocate(resource struct {
        handle Handle:RESOURCE;
        count uint32;
    }) -> (resource struct {
        out_allocation Handle;
    }) error Status;

    /// ## Summary
    ///
    /// Create an Interrupt object from a Messaged-Signaled Interrupt (MSI) allocation.
    ///
    /// ## Declaration
    ///
    /// ```c
    /// #include <zircon/syscalls.h>
    ///
    /// zx_status_t zx_msi_create(zx_handle_t handle,
    ///                           uint32_t options,
    ///                           uint32_t msi_id,
    ///                           zx_handle_t vmo,
    ///                           size_t vmo_offset,
    ///                           zx_handle_t* out_interrupt);
    /// ```
    ///
    /// ## Description
    ///
    /// `zx_msi_create()` creates an Interrupt object corresponding to a given MSI
    /// within an MSI allocation *handle* created by [`zx_msi_allocate()`]. This
    /// object can be used with the various interrupt syscalls in the same manner one
    /// would use an Interrupt object returned by [`zx_interrupt_create()`]. Only one
    /// Interrupt object can be created per *msi_id* at a time, but the same *vmo* and
    /// *vmo_offset* is usable for multiple MSIs created from the same MSI allocation
    /// object. This allows for a holder of the *root resource* to both allocate vectors
    /// and MSIs from the system, as well as create Interrupt objects corresponding to
    /// those vectors for use in device drivers.
    ///
    /// *vmo* should be a handle referring to a physical vmo (created through
    /// *[`zx_vmo_create_physical()`]) with the cache policy
    /// *ZX_CACHE_POLICY_UNCACHED_DEVICE. For test purposes a contiguous
    /// *[`zx_vmo_create_contiguous()`] vmo can be used.
    ///
    /// *msi_id* corresponds to the vector in a given MSI allocation to create an Interrupt
    /// object for. *msi_id* must be be between 0 and the allocation size minus 1, inclusive.
    ///
    /// *vmo_offset* corresponds to the offset within *vmo* where the MSI capability
    /// structure begins. Details of this structure can be found in the PCI Local Bus
    /// Specification v3.0, section 6.8.
    ///
    /// *options* should be 0.
    ///
    /// ## Rights
    ///
    /// *handle* must be of type `ZX_OBJ_TYPE_MSI`.
    ///
    /// *vmo* must be of type `ZX_OBJ_TYPE_VMO`.
    ///
    /// *vmo* must have `ZX_RIGHT_MAP`.
    ///
    /// ## Return value
    ///
    /// `zx_msi_create()` returns `ZX_OK` on success. In the event of failure, a
    /// negative error value is returned.
    ///
    /// ## Errors
    ///
    /// `ZX_ERR_BAD_HANDLE` the *handle* is invalid.
    ///
    /// `ZX_ERR_WRONG_TYPE` *handle* is not the appropriate type.
    ///
    /// `ZX_ERR_INVALID_ARGS` *msi_id* is not a valid MSI id within the allocation
    /// referred to by *handle*, *vmo* is not the size of a ZX_PAGE_SIZE, *vmo* is
    /// not physical or contiguous, *vmo* does not have cache policy set to
    /// ZX_CACHE_POLICY_UNCACHED_DEVICE, *vmo* does not appear to contain a supported
    /// MSI/MSI-X capability, *vmo_offset* is out of bounds of *vmo*, *vmo_offset* is
    /// invalid for the type of capability structure found, *options* is not 0, or
    /// *out_interrupt* is NULL.
    ///
    /// `ZX_ERR_ALREADY_BOUND` An Interrupt object corresponding to *msi_id* already
    /// *exists.
    ///
    /// ## See also
    ///
    ///  - [`zx_interrupt_wait()`]
    ///  - [`zx_msi_allocate()`]
    ///  - [`zx_vmo_create_contiguous()`]
    ///  - [`zx_vmo_create_physical()`]
    ///  - [`zx_vmo_set_cache_policy()`]
    ///
    /// [`zx_interrupt_create()`]: interrupt_create.md
    /// [`zx_interrupt_wait()`]: interrupt_wait.md
    /// [`zx_msi_allocate()`]: msi_allocate.md
    /// [`zx_vmo_create_contiguous()`]: vmo_create_contiguous.md
    /// [`zx_vmo_create_physical()`]: vmo_create_physical.md
    /// [`zx_vmo_set_cache_policy()`]: vmo_set_cache_policy.md
    strict Create(resource struct {
        handle Handle;
        options uint32;
        msi_id uint32;
        vmo Handle:VMO;
        vmo_offset usize64;
    }) -> (resource struct {
        out_interrupt Handle;
    }) error Status;
};