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559a779c6a
The ObjectDeref trait now provides all the magic that is required to fake inheritance. Replace the "impl SysBusDevice" block of qemu_api::sysbus with a trait, so that sysbus_init_irq() can be invoked as "self.init_irq()" without any intermediate upcast. Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
90 lines
2.7 KiB
Rust
90 lines
2.7 KiB
Rust
// Copyright 2024 Red Hat, Inc.
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// Author(s): Paolo Bonzini <pbonzini@redhat.com>
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// SPDX-License-Identifier: GPL-2.0-or-later
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//! Bindings for interrupt sources
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use core::ptr;
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use std::{marker::PhantomData, os::raw::c_int};
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use crate::{
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bindings::{qemu_set_irq, IRQState},
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prelude::*,
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};
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/// Interrupt sources are used by devices to pass changes to a value (typically
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/// a boolean). The interrupt sink is usually an interrupt controller or
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/// GPIO controller.
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///
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/// As far as devices are concerned, interrupt sources are always active-high:
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/// for example, `InterruptSource<bool>`'s [`raise`](InterruptSource::raise)
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/// method sends a `true` value to the sink. If the guest has to see a
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/// different polarity, that change is performed by the board between the
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/// device and the interrupt controller.
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///
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/// Interrupts are implemented as a pointer to the interrupt "sink", which has
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/// type [`IRQState`]. A device exposes its source as a QOM link property using
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/// a function such as [`SysBusDeviceMethods::init_irq`], and
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/// initially leaves the pointer to a NULL value, representing an unconnected
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/// interrupt. To connect it, whoever creates the device fills the pointer with
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/// the sink's `IRQState *`, for example using `sysbus_connect_irq`. Because
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/// devices are generally shared objects, interrupt sources are an example of
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/// the interior mutability pattern.
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///
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/// Interrupt sources can only be triggered under the Big QEMU Lock; `BqlCell`
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/// allows access from whatever thread has it.
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#[derive(Debug)]
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#[repr(transparent)]
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pub struct InterruptSource<T = bool>
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where
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c_int: From<T>,
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{
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cell: BqlCell<*mut IRQState>,
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_marker: PhantomData<T>,
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}
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impl InterruptSource<bool> {
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/// Send a low (`false`) value to the interrupt sink.
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pub fn lower(&self) {
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self.set(false);
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}
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/// Send a high-low pulse to the interrupt sink.
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pub fn pulse(&self) {
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self.set(true);
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self.set(false);
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}
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/// Send a high (`true`) value to the interrupt sink.
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pub fn raise(&self) {
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self.set(true);
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}
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}
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impl<T> InterruptSource<T>
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where
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c_int: From<T>,
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{
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/// Send `level` to the interrupt sink.
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pub fn set(&self, level: T) {
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let ptr = self.cell.get();
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// SAFETY: the pointer is retrieved under the BQL and remains valid
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// until the BQL is released, which is after qemu_set_irq() is entered.
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unsafe {
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qemu_set_irq(ptr, level.into());
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}
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}
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pub(crate) const fn as_ptr(&self) -> *mut *mut IRQState {
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self.cell.as_ptr()
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}
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}
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impl Default for InterruptSource {
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fn default() -> Self {
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InterruptSource {
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cell: BqlCell::new(ptr::null_mut()),
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_marker: PhantomData,
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}
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}
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}
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