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drasko |
/*
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* Userspace irq handling and management
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*
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* Copyright (C) 2009 Bahadir Balban
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*/
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#include <l4/api/irq.h>
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#include <l4/api/errno.h>
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#include <l4/generic/scheduler.h>
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#include <l4/generic/thread.h>
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#include <l4/generic/capability.h>
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#include <l4/generic/irq.h>
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#include <l4/generic/tcb.h>
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#include INC_GLUE(message.h)
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#include <l4/lib/wait.h>
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#include INC_SUBARCH(irq.h)
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/*
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* Default function that handles userspace
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* threaded irqs. Increases irq count and wakes
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* up any waiters.
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*
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* The increment is a standard read/update/write, and
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* it is atomic due to multiple reasons:
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*
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* - We are atomic with regard to the task because we are
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* in irq context. Task cannot run during the period where
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* we read update and write the value.
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*
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* - The task does an atomic swap on reads, writing 0 to the
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* location in the same instruction as it reads it. As a
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* result task updates on the slot are atomic, and cannot
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* interfere with the read/update/write of the irq.
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*
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* - Recursive irqs are enabled, but we are also protected
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* from them because the current irq number is masked.
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*
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* FIXME: Instead of UTCB, do it by incrementing a semaphore.
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*/
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int irq_thread_notify(struct irq_desc *desc)
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{
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struct utcb *utcb;
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int err;
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/* Make sure irq thread's utcb is mapped */
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if ((err = tcb_check_and_lazy_map_utcb(desc->task,
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0)) < 0) {
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printk("%s: Irq occured but registered task's utcb "
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"is inaccessible without a page fault. "
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"task id=0x%x err=%d\n"
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"Destroying task.", __FUNCTION__,
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desc->task->tid, err);
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/* FIXME: Racy for irqs. */
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thread_destroy(desc->task);
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/* FIXME: Deregister and disable irq as well */
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}
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/* Get thread's utcb */
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utcb = (struct utcb *)desc->task->utcb_address;
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/* Atomic increment (See above comments) with no wraparound */
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if (utcb->notify[desc->task_notify_slot] != TASK_NOTIFY_MAXVALUE)
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utcb->notify[desc->task_notify_slot]++;
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/* Async wake up any waiter irq threads */
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wake_up(&desc->wqh_irq, WAKEUP_ASYNC);
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BUG_ON(!irqs_enabled());
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return 0;
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}
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/*
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* Register the given globally unique irq number with the
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* current thread with given flags
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*/
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int irq_control_register(struct ktcb *task, int slot, l4id_t irqnum)
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{
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int err;
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/*
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* Check that utcb memory accesses won't fault us.
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*
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* We make sure that the irq registrar has its utcb mapped,
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* so that if an irq occurs, the utcb address must be at
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* least readily available to be copied over to the page
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* tables of the task runnable at the time of the irq.
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*/
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if ((err = tcb_check_and_lazy_map_utcb(current, 1)) < 0)
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return err;
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/* Register the irq for thread notification */
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if ((err = irq_register(current, slot, irqnum)) < 0)
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return err;
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/* Make thread a real-time task */
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current->flags |= TASK_REALTIME;
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return 0;
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}
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/*
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* Makes current task wait on the given irq
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*/
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int irq_wait(l4id_t irq_index)
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{
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struct irq_desc *desc = irq_desc_array + irq_index;
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struct utcb *utcb = (struct utcb *)current->utcb_address;
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int ret;
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/* Index must be valid */
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if (irq_index > IRQS_MAX || irq_index < 0)
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return -EINVAL;
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/* UTCB must be mapped */
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if ((ret = tcb_check_and_lazy_map_utcb(current, 1)) < 0)
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return ret;
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/* Wait until the irq changes slot value */
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WAIT_EVENT(&desc->wqh_irq,
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utcb->notify[desc->task_notify_slot] != 0,
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ret);
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if (ret < 0)
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return ret;
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else
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return l4_atomic_dest_readb(&utcb->notify[desc->task_notify_slot]);
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}
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/*
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* Register/deregister device irqs. Optional synchronous and
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* asynchronous irq handling.
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*/
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int sys_irq_control(unsigned int req, unsigned int flags, l4id_t irqnum)
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{
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/* Currently a task is allowed to register only for itself */
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struct ktcb *task = current;
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int err;
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if ((err = cap_irq_check(task, req, flags, irqnum)) < 0)
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return err;
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switch (req) {
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case IRQ_CONTROL_REGISTER:
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return irq_control_register(task, flags, irqnum);
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case IRQ_CONTROL_WAIT:
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return irq_wait(irqnum);
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default:
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return -EINVAL;
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}
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return 0;
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}
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