IRQ: Add base class for shared IRQs

Added generic 'Irq_proxy' class to core includes (ported from base-okl4). It can
be used to implement shared IRQ support for various base platforms. It will
generate one thread per IRQ and unblocks waiting clients (IRQ sessions) upon
interrupt receipt.

Issue #390
This commit is contained in:
Sebastian Sumpf 2012-10-05 14:28:24 +02:00 committed by Norman Feske
parent ff0c7825e4
commit 5549f6413b

View File

@ -0,0 +1,267 @@
/**
* \brief Shared-interrupt support
* \author Christian Helmuth
* \author Sebastian Sumpf
* \date 2009-12-15
*/
#ifndef _CORE__INCLUDE__IRQ_PROXY_H_
#define _CORE__INCLUDE__IRQ_PROXY_H_
#include <base/env.h>
#include <util.h>
#include <base/thread.h>
namespace Genode {
class Irq_blocker;
template <typename THREAD> class Irq_proxy;
class Irq_thread_dummy;
class Irq_proxy_single;
}
class Genode::Irq_blocker : public Genode::List<Genode::Irq_blocker>::Element
{
private:
Lock _wait_lock;
public:
Irq_blocker() : _wait_lock(Lock::LOCKED) { }
void block() { _wait_lock.lock(); }
void unblock() { _wait_lock.unlock(); }
};
/*
* Proxy thread that associates to the interrupt and unblocks waiting irqctrl
* threads. Maybe, we should utilize our signals for interrupt delivery...
*
* XXX resources are not accounted as the interrupt is shared
*/
template <typename THREAD>
class Genode::Irq_proxy : public THREAD,
public Genode::List<Genode::Irq_proxy<THREAD> >::Element
{
protected:
char _name[32];
Lock _startup_lock;
long _irq_number;
Lock _mutex; /* protects this object */
int _num_sharers; /* number of clients sharing this IRQ */
Semaphore _sleep; /* wake me up if aspired blockers return */
List<Irq_blocker> _blocker_list;
int _num_blockers; /* number of currently blocked clients */
bool _woken_up; /* client decided to wake me up -
this prevents multiple wakeups
to happen during initialization */
/***************
** Interface **
***************/
/**
* Request interrupt
*
* \return true on success
*/
virtual bool _associate() = 0;
/**
* Wait for associated interrupt
*/
virtual void _wait_for_irq() = 0;
/**
* Acknowledge interrupt
*/
virtual void _ack_irq() = 0;
/********************
** Implementation **
********************/
const char *_construct_name(long irq_number)
{
snprintf(_name, sizeof(_name), "irqproxy%02lx", irq_number);
return _name;
}
void _loop()
{
/* wait for first blocker */
_sleep.down();
while (1) {
_wait_for_irq();
{
Lock::Guard lock_guard(_mutex);
/* inform blocked clients */
Irq_blocker *b;
while ((b = _blocker_list.first())) {
_blocker_list.remove(b);
b->unblock();
}
/* reset blocker state */
_num_blockers = 0;
_woken_up = false;
}
/*
* We must wait for all clients to ack their interrupt,
* otherwise level-triggered interrupts will occur immediately
* after acknowledgement. That's an inherent security problem
* with shared IRQs and induces problems with dynamic driver
* load and unload.
*/
_sleep.down();
/* acknowledge previous interrupt */
_ack_irq();
}
}
/**
* Start this thread, should be called externally from derived class
*/
virtual void _start()
{
THREAD::start();
_startup_lock.lock();
}
public:
Irq_proxy(long irq_number)
:
THREAD(_construct_name(irq_number)),
_startup_lock(Lock::LOCKED), _irq_number(irq_number),
_mutex(Lock::UNLOCKED), _num_sharers(0), _num_blockers(0), _woken_up(false)
{ }
/**
* Thread interface
*/
void entry()
{
if (_associate()) {
_startup_lock.unlock();
_loop();
}
}
/**
* Block until interrupt occured
*/
virtual void wait_for_irq()
{
Irq_blocker blocker;
{
Lock::Guard lock_guard(_mutex);
_blocker_list.insert(&blocker);
_num_blockers++;
/*
* The proxy thread is woken up if no client woke it up before
* and this client is the last aspired blocker.
*/
if (!_woken_up && _num_blockers == _num_sharers) {
_sleep.up();
_woken_up = true;
}
}
blocker.block();
}
long irq_number() const { return _irq_number; }
virtual bool add_sharer()
{
Lock::Guard lock_guard(_mutex);
++_num_sharers;
return true;
}
template <typename PROXY>
static PROXY *get_irq_proxy(long irq_number, Range_allocator *irq_alloc = 0)
{
static List<Irq_proxy> proxies;
static Lock proxies_lock;
Lock::Guard lock_guard(proxies_lock);
/* lookup proxy in database */
for (Irq_proxy *p = proxies.first(); p; p = p->next())
if (p->irq_number() == irq_number)
return static_cast<PROXY *>(p);
/* try to create proxy */
if (!irq_alloc || irq_alloc->alloc_addr(1, irq_number) != Range_allocator::ALLOC_OK)
return false;
PROXY *new_proxy = new (env()->heap()) PROXY(irq_number);
proxies.insert(new_proxy);
return new_proxy;
}
};
/**
* Dummy thread
*/
class Genode::Irq_thread_dummy
{
public:
Irq_thread_dummy(char const *name) { }
void start() { }
};
/**
* Non-threaded proxy that disables shared interrupts
*/
class Genode::Irq_proxy_single : public Genode::Irq_proxy<Genode::Irq_thread_dummy>
{
protected:
void _start()
{
_associate();
}
public:
Irq_proxy_single(long irq_number) : Irq_proxy(irq_number) { }
bool add_sharer()
{
Lock::Guard lock_guard(_mutex);
if (_num_sharers)
return false;
_num_sharers = 1;
return true;
}
void wait_for_irq()
{
_wait_for_irq();
_ack_irq();
}
};
#endif /* _CORE__INCLUDE__IRQ_PROXY_H_ */