flight/pios/stm32f0x/pios_irq.c

   1 /**
   2  ******************************************************************************
   3  * @addtogroup PIOS PIOS Core hardware abstraction layer
   4  * @{
   5  * @addtogroup PIOS_IRQ IRQ Setup Functions
   6  * @brief STM32 Hardware code to enable and disable interrupts
   7  * @{
   8  *
   9  * @file       pios_irq.c
  10  * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
  11  *              Parts by Thorsten Klose (tk@midibox.org) (tk@midibox.org)
  12  * @brief      IRQ Enable/Disable routines
  13  * @see        The GNU Public License (GPL) Version 3
  14  *
  15  *****************************************************************************/
  16 /*
  17  * This program is free software; you can redistribute it and/or modify
  18  * it under the terms of the GNU General Public License as published by
  19  * the Free Software Foundation; either version 3 of the License, or
  20  * (at your option) any later version.
  21  *
  22  * This program is distributed in the hope that it will be useful, but
  23  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  24  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  25  * for more details.
  26  *
  27  * You should have received a copy of the GNU General Public License along
  28  * with this program; if not, write to the Free Software Foundation, Inc.,
  29  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  30  */
  31
  32 #include "pios.h"
  33
  34 #ifdef PIOS_INCLUDE_IRQ
  35
  36 /* Private Function Prototypes */
  37
  38 /* Local Variables */
  39 /* The nesting counter ensures, that interrupts won't be enabled so long nested functions disable them */
  40 static uint32_t nested_ctr;
  41
  42 /* Stored priority level before IRQ has been disabled (important for co-existence with vPortEnterCritical) */
  43 static uint32_t prev_primask;
  44
  45 /**
  46  * Disables all interrupts (nested)
  47  * \return < 0 On errors
  48  */
  49 int32_t PIOS_IRQ_Disable(void)
  50 {
  51     /* Get current priority if nested level == 0 */
  52     if (!nested_ctr) {
  53         __asm volatile ("   mrs %0, primask\n" : "=r" (prev_primask)
  54                         );
  55     }
  56
  57     /* Disable interrupts */
  58     __asm volatile ("     mov r0, #1     \n" "     msr primask, r0\n" ::: "r0");
  59
  60     ++nested_ctr;
  61
  62     /* No error */
  63     return 0;
  64 }
  65
  66 /**
  67  * Enables all interrupts (nested)
  68  * \return < 0 on errors
  69  * \return -1 on nesting errors (PIOS_IRQ_Disable() hasn't been called before)
  70  */
  71 int32_t PIOS_IRQ_Enable(void)
  72 {
  73     /* Check for nesting error */
  74     if (nested_ctr == 0) {
  75         /* Nesting error */
  76         return -1;
  77     }
  78
  79     /* Decrease nesting level */
  80     --nested_ctr;
  81
  82     /* Set back previous priority once nested level reached 0 again */
  83     if (nested_ctr == 0) {
  84         __asm volatile ("   msr primask, %0\n" ::"r" (prev_primask)
  85                         );
  86     }
  87
  88     /* No error */
  89     return 0;
  90 }
  91
  92 #endif /* PIOS_INCLUDE_IRQ */
  93
  94 /**
  95  * @}
  96  * @}
  97  */