genode/repos/os/include/platform/irq_proxy.h

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/**
* \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>
namespace Genode {
class Irq_sigh;
template <typename THREAD> class Irq_proxy;
}
class Genode::Irq_sigh : public Genode::Signal_context_capability,
public Genode::List<Genode::Irq_sigh>::Element
{
public:
inline Irq_sigh * operator= (const Signal_context_capability &cap)
{
Signal_context_capability::operator=(cap);
return this;
}
Irq_sigh() { }
void notify() { Genode::Signal_transmitter(*this).submit(1); }
};
/*
* Proxy thread that associates to the interrupt and unblocks waiting irqctrl
* threads.
*
* 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_sigh> _sigh_list;
int _num_acknowledgers; /* 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();
/* notify all */
notify_about_irq(1);
/*
* 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_acknowledgers(0), _woken_up(false)
{ }
/**
* Thread interface
*/
void entry()
{
bool const associate_suceeded = _associate();
_startup_lock.unlock();
if (associate_suceeded)
_loop();
}
/**
* Acknowledgements of clients
*/
virtual bool ack_irq()
{
Lock::Guard lock_guard(_mutex);
_num_acknowledgers++;
/*
* The proxy thread has to be woken up if no client woke it up
* before and this client is the last aspired acknowledger.
*/
if (!_woken_up && _num_acknowledgers == _num_sharers) {
_sleep.up();
_woken_up = true;
}
return _woken_up;
}
/**
* Notify all clients about irq
*/
void notify_about_irq(unsigned)
{
Lock::Guard lock_guard(_mutex);
/* reset acknowledger state */
_num_acknowledgers = 0;
_woken_up = false;
/* inform blocked clients */
for (Irq_sigh * s = _sigh_list.first(); s ; s = s->next())
s->notify();
}
long irq_number() const { return _irq_number; }
virtual bool add_sharer(Irq_sigh *s)
{
Lock::Guard lock_guard(_mutex);
++_num_sharers;
_sigh_list.insert(s);
return true;
}
virtual bool remove_sharer(Irq_sigh *s)
{
Lock::Guard lock_guard(_mutex);
_sigh_list.remove(s);
--_num_sharers;
if (_woken_up)
return _num_sharers == 0;
if (_num_acknowledgers == _num_sharers) {
_sleep.up();
_woken_up = true;
}
return _num_sharers == 0;
}
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).is_error())
return 0;
PROXY *new_proxy = new (env()->heap()) PROXY(irq_number);
proxies.insert(new_proxy);
return new_proxy;
}
};
#endif /* _CORE__INCLUDE__IRQ_PROXY_H_ */