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dde_linux: lx_emul interface for GPIO pin access
This patch introduces the lx_emul/pin.h interface that enables GPIO stub drivers to interact with Genode's Pin_control and IRQ sessions via a simple C API. Fixes #4316
This commit is contained in:
Norman Feske
Christian Helmuth
parent
f2a627c107
commit
449f647e58
50
repos/dde_linux/src/include/lx_emul/pin.h
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repos/dde_linux/src/include/lx_emul/pin.h
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/*
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* \brief Lx_emul support for accessing GPIO pins
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* \author Norman Feske
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* \date 2021-11-02
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*/
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/*
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* Copyright (C) 2021 Genode Labs GmbH
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*
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* This file is distributed under the terms of the GNU General Public License
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* version 2.
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*/
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#ifndef _LX_EMUL__PIN_H_
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#define _LX_EMUL__PIN_H_
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* Set output state of GPIO pin
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*
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* \pin_name GPIO name used as label for corresponding 'Pin_control' session
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*/
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void lx_emul_pin_control(char const *pin_name, bool enabled);
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/**
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* Request interrupt backed by an IRQ session
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*/
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void lx_emul_pin_irq_unmask(unsigned gic_irq, unsigned pin_irq,
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char const *pin_name);
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/**
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* Return pin IRQ number of most recently occurred pin interrupt
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*
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* This function is meant to be called by the PIO driver's interrupt handler.
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*/
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unsigned lx_emul_pin_last_irq(void);
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/**
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* Acknowledge GPIO interrupt
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*/
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void lx_emul_pin_irq_ack(unsigned pin_irq);
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#ifdef __cplusplus
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}
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#endif
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#endif /* _LX_EMUL__PIN_H_ */
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231
repos/dde_linux/src/lib/lx_emul/pin.cc
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repos/dde_linux/src/lib/lx_emul/pin.cc
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/*
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* \brief Lx_emul backend for accessing GPIO pins
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* \author Norman Feske
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* \date 2021-11-02
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*/
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/*
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* Copyright (C) 2021 Genode Labs GmbH
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*
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* This file is distributed under the terms of the GNU General Public License
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* version 2.
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*/
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/* Genode includes */
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#include <base/registry.h>
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#include <pin_control_session/connection.h>
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#include <irq_session/connection.h>
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#include <lx_emul/pin.h>
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#include <lx_kit/env.h>
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namespace {
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using namespace Genode;
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class Global_irq_controller : Noncopyable
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{
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private:
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Lx_kit::Env &_env;
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public:
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struct Number { unsigned value; };
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Global_irq_controller(Lx_kit::Env &env) : _env(env) { }
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void trigger_irq(Number number)
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{
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/*
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* Mirrored from 'Lx_kit::Device::Irq::handle'
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*/
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_env.last_irq = number.value;
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_env.scheduler.unblock_irq_handler();
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_env.scheduler.schedule();
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}
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};
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using Pin_name = Session_label;
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using Gic_irq_number = Global_irq_controller::Number;
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struct Pin_irq_number { unsigned value; };
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struct Irq_info
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{
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Gic_irq_number gic_irq_number;
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Pin_irq_number pin_irq_number;
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};
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struct Pin_irq_handler : Interface
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{
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virtual void handle_pin_irq(Irq_info) = 0;
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};
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struct Pin : Interface
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{
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using Name = Session_label;
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Env &_env;
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Pin_irq_handler &_pin_irq_handler;
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Irq_info _irq_info { };
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Name const name;
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Constructible<Pin_control::Connection> _control { };
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Constructible<Irq_connection> _irq { };
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Io_signal_handler<Pin> _irq_handler { _env.ep(), *this, &Pin::_handle_irq };
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void _handle_irq()
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{
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_pin_irq_handler.handle_pin_irq(_irq_info);
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}
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Pin(Env &env, Name const &name, Pin_irq_handler &pin_irq_handler)
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:
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_env(env), _pin_irq_handler(pin_irq_handler), name(name)
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{ }
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void control(bool enabled)
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{
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if (_irq.constructed()) {
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error("attempt to drive interrupt pin ", name, " as output");
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return;
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}
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if (!_control.constructed())
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_control.construct(_env, name.string());
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_control->state(enabled);
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}
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void associate_with_gic_and_unmask_irq(Irq_info irq_info)
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{
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_control.destruct();
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if (!_irq.constructed()) {
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_irq_info = irq_info;
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_irq.construct(_env, _irq_info.pin_irq_number.value);
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_irq->sigh(_irq_handler);
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_irq->ack_irq();
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}
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}
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void ack_matching_irq(Pin_irq_number ack_pin)
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{
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if (ack_pin.value != _irq_info.pin_irq_number.value)
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return;
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if (_irq.constructed())
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_irq->ack_irq();
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}
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};
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struct Pins : private Pin_irq_handler
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{
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Env &_env;
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Allocator &_alloc;
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Global_irq_controller &_gic;
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Registry<Registered<Pin> > _registry { };
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Pin_irq_number last_irq { };
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Pins(Env &env, Allocator &alloc, Global_irq_controller &gic)
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:
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_env(env), _alloc(alloc), _gic(gic)
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{ }
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template <typename FN>
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void with_pin(Pin::Name const &name, FN const &fn)
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{
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Pin_irq_handler &pin_irq_handler = *this;
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/*
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* Construct 'Pin' object on demand, apply 'fn' if constructed
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*/
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for (unsigned i = 0; i < 2; i++) {
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bool done = false;
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_registry.for_each([&] (Pin &pin) {
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if (pin.name == name) {
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fn(pin);
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done = true;
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}
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});
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if (done)
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break;
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new (_alloc) Registered<Pin>(_registry, _env, name, pin_irq_handler);
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/* ... apply 'fn' in second iteration */
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}
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}
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void handle_pin_irq(Irq_info irq_info) override
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{
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last_irq = irq_info.pin_irq_number;
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_gic.trigger_irq(irq_info.gic_irq_number);
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}
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void irq_ack(Pin_irq_number ack_pin_number)
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{
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_registry.for_each([&] (Pin &pin) {
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pin.ack_matching_irq(ack_pin_number); });
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}
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};
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};
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static Pins &pins()
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{
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static Global_irq_controller gic { Lx_kit::env() };
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static Pins pins { Lx_kit::env().env, Lx_kit::env().heap, gic };
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return pins;
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}
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extern "C" void lx_emul_pin_control(char const *pin_name, bool enabled)
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{
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pins().with_pin(pin_name, [&] (Pin &pin) {
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pin.control(enabled); });
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}
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extern "C" void lx_emul_pin_irq_unmask(unsigned gic_irq, unsigned pin_irq,
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char const *pin_name)
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{
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/*
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* Translate GIC IRQ number as known by the Linux kernel into the
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* physical IRQ number expected by 'Lx_kit::Env::last_irq'.
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*/
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gic_irq += 32;
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pins().with_pin(pin_name, [&] (Pin &pin) {
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Irq_info const irq_info { .gic_irq_number = { gic_irq },
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.pin_irq_number = { pin_irq } };
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pin.associate_with_gic_and_unmask_irq(irq_info);
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});
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}
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extern "C" void lx_emul_pin_irq_ack(unsigned pin_irq)
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{
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pins().irq_ack( Pin_irq_number { pin_irq } );
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}
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extern "C" unsigned lx_emul_pin_last_irq(void)
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{
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return pins().last_irq.value;
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}
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