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/*
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 * Copyright (c) 2007 Petr Stepan
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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/** @addtogroup arm32
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 * @{
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 */
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/** @file
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 *  @brief Interrupts controlling routines.
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 */
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#include <arch/asm.h>
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#include <arch/regutils.h>
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#include <arch/drivers/gxemul.h>
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#include <ddi/irq.h>
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#include <ddi/device.h>
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#include <interrupt.h>
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/** Initial size of a table holding interrupt handlers. */
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#define IRQ_COUNT 8
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static irq_t gxemul_timer_irq;
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/** Disable interrupts.
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 *
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 * @return Old interrupt priority level.
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 */
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ipl_t interrupts_disable(void)
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{
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    ipl_t ipl = current_status_reg_read();
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    current_status_reg_control_write(STATUS_REG_IRQ_DISABLED_BIT | ipl);
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    return ipl;
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}
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/** Enable interrupts.
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 *
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 * @return Old interrupt priority level.
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 */
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ipl_t interrupts_enable(void)
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{
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    ipl_t ipl = current_status_reg_read();
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    current_status_reg_control_write(ipl & ~STATUS_REG_IRQ_DISABLED_BIT);
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    return ipl;
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}
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/** Restore interrupt priority level.
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 *
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 * @param ipl Saved interrupt priority level.
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 */
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void interrupts_restore(ipl_t ipl)
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{
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    current_status_reg_control_write(
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        (current_status_reg_read() & ~STATUS_REG_IRQ_DISABLED_BIT) |
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        (ipl & STATUS_REG_IRQ_DISABLED_BIT));
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}
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/** Read interrupt priority level.
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 *
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 * @return Current interrupt priority level.
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 */
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ipl_t interrupts_read(void)
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{
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    return current_status_reg_read();
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}
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/** Starts gxemul Real Time Clock device, which asserts regular interrupts.
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 *
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 * @param frequency Interrupts frequency (0 disables RTC).
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 */
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static void gxemul_timer_start(uint32_t frequency)
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{
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    *((uint32_t *) (gxemul_rtc + GXEMUL_RTC_FREQ_OFFSET))
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        = frequency;
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}
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static irq_ownership_t gxemul_timer_claim(irq_t *irq)
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{
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    return IRQ_ACCEPT;
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}
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/** Timer interrupt handler.
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 *
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 * @param irq Interrupt information.
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 * @param arg Not used.
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 */
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static void gxemul_timer_irq_handler(irq_t *irq)
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{
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    /*
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    * We are holding a lock which prevents preemption.
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    * Release the lock, call clock() and reacquire the lock again.
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    */
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    spinlock_unlock(&irq->lock);
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    clock();
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    spinlock_lock(&irq->lock);
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    /* acknowledge tick */
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    *((uint32_t *) (gxemul_rtc + GXEMUL_RTC_ACK_OFFSET))
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        = 0;
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}
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/** Initialize basic tables for exception dispatching
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 * and starts the timer.
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 */
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void interrupt_init(void)
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{
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    irq_init(IRQ_COUNT, IRQ_COUNT);
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    irq_initialize(&gxemul_timer_irq);
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    gxemul_timer_irq.devno = device_assign_devno();
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    gxemul_timer_irq.inr = GXEMUL_TIMER_IRQ;
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    gxemul_timer_irq.claim = gxemul_timer_claim;
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    gxemul_timer_irq.handler = gxemul_timer_irq_handler;
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    irq_register(&gxemul_timer_irq);
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    gxemul_timer_start(GXEMUL_TIMER_FREQ);
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}
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/** @}
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 */