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  1. /*
  2.  * Copyright (c) 2007 Petr Stepan
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /** @addtogroup arm32
  30.  * @{
  31.  */
  32. /** @file
  33.  *  @brief Interrupts controlling routines.
  34.  */
  35.  
  36. #include <arch/asm.h>
  37. #include <arch/regutils.h>
  38. #include <arch/drivers/gxemul.h>
  39. #include <ddi/irq.h>
  40. #include <ddi/device.h>
  41. #include <interrupt.h>
  42.  
  43. /** Initial size of a table holding interrupt handlers. */
  44. #define IRQ_COUNT 8
  45.  
  46. static irq_t gxemul_timer_irq;
  47.  
  48. /** Disable interrupts.
  49.  *
  50.  * @return Old interrupt priority level.
  51.  */
  52. ipl_t interrupts_disable(void)
  53. {
  54.     ipl_t ipl = current_status_reg_read();
  55.    
  56.     current_status_reg_control_write(STATUS_REG_IRQ_DISABLED_BIT | ipl);
  57.    
  58.     return ipl;
  59. }
  60.  
  61. /** Enable interrupts.
  62.  *
  63.  * @return Old interrupt priority level.
  64.  */
  65. ipl_t interrupts_enable(void)
  66. {
  67.     ipl_t ipl = current_status_reg_read();
  68.    
  69.     current_status_reg_control_write(ipl & ~STATUS_REG_IRQ_DISABLED_BIT);
  70.    
  71.     return ipl;
  72. }
  73.  
  74. /** Restore interrupt priority level.
  75.  *
  76.  * @param ipl Saved interrupt priority level.
  77.  */
  78. void interrupts_restore(ipl_t ipl)
  79. {
  80.     current_status_reg_control_write(
  81.         (current_status_reg_read() & ~STATUS_REG_IRQ_DISABLED_BIT) |
  82.         (ipl & STATUS_REG_IRQ_DISABLED_BIT));
  83. }
  84.  
  85. /** Read interrupt priority level.
  86.  *
  87.  * @return Current interrupt priority level.
  88.  */
  89. ipl_t interrupts_read(void)
  90. {
  91.     return current_status_reg_read();
  92. }
  93.  
  94. /** Starts gxemul Real Time Clock device, which asserts regular interrupts.
  95.  *
  96.  * @param frequency Interrupts frequency (0 disables RTC).
  97.  */
  98. static void gxemul_timer_start(uint32_t frequency)
  99. {
  100.     *((uint32_t *) (gxemul_rtc + GXEMUL_RTC_FREQ_OFFSET))
  101.         = frequency;
  102. }
  103.  
  104. static irq_ownership_t gxemul_timer_claim(irq_t *irq)
  105. {
  106.     return IRQ_ACCEPT;
  107. }
  108.  
  109. /** Timer interrupt handler.
  110.  *
  111.  * @param irq Interrupt information.
  112.  * @param arg Not used.
  113.  */
  114. static void gxemul_timer_irq_handler(irq_t *irq)
  115. {
  116.     /*
  117.     * We are holding a lock which prevents preemption.
  118.     * Release the lock, call clock() and reacquire the lock again.
  119.     */
  120.     spinlock_unlock(&irq->lock);
  121.     clock();
  122.     spinlock_lock(&irq->lock);
  123.    
  124.     /* acknowledge tick */
  125.     *((uint32_t *) (gxemul_rtc + GXEMUL_RTC_ACK_OFFSET))
  126.         = 0;
  127. }
  128.  
  129. /** Initialize basic tables for exception dispatching
  130.  * and starts the timer.
  131.  */
  132. void interrupt_init(void)
  133. {
  134.     irq_init(IRQ_COUNT, IRQ_COUNT);
  135.    
  136.     irq_initialize(&gxemul_timer_irq);
  137.     gxemul_timer_irq.devno = device_assign_devno();
  138.     gxemul_timer_irq.inr = GXEMUL_TIMER_IRQ;
  139.     gxemul_timer_irq.claim = gxemul_timer_claim;
  140.     gxemul_timer_irq.handler = gxemul_timer_irq_handler;
  141.    
  142.     irq_register(&gxemul_timer_irq);
  143.    
  144.     gxemul_timer_start(GXEMUL_TIMER_FREQ);
  145. }
  146.  
  147. /** @}
  148.  */
  149.