Subversion Repositories neorv32

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// # << NEORV32: neorv32_xirq.c - External Interrupt controller HW Driver >>                       #

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// # BSD 3-Clause License                                                                          #

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// # Copyright (c) 2021, Stephan Nolting. All rights reserved.                                     #

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// # The NEORV32 Processor - https://github.com/stnolting/neorv32              (c) Stephan Nolting #

// #################################################################################################

/**********************************************************************//**

 * @file neorv32_xirq.c

 * @author Stephan Nolting

 * @brief External Interrupt controller HW driver source file.

 **************************************************************************/

#include "neorv32.h"

#include "neorv32_xirq.h"

/**********************************************************************//**

 * The >private< trap vector look-up table of the XIRQ.

 **************************************************************************/

static uint32_t __neorv32_xirq_vector_lut[32] __attribute__((unused)); // trap handler vector table

// private functions

static void __attribute__((aligned(16))) __neorv32_xirq_core(void);

static void __neorv32_xirq_dummy_handler(void);

/**********************************************************************//**

 * Check if external interrupt controller was synthesized.

 *

 * @return 0 if XIRQ was not synthesized, 1 if EXTIRQ is available.

 **************************************************************************/

int neorv32_xirq_available(void) {

  if (NEORV32_SYSINFO.SOC & (1 << SYSINFO_SOC_IO_XIRQ)) {

    return 1;

  }

  else {

    return 0;

  }

}

/**********************************************************************//**

 * Initialize XIRQ controller.

 *

 * @note All interrupt channels will be deactivated, all pending IRQs will be deleted and all

 * handler addresses will be deleted.

 * @return 0 if success, 1 if error.

 **************************************************************************/

int neorv32_xirq_setup(void) {

  NEORV32_XIRQ.IER = 0; // disable all input channels

  NEORV32_XIRQ.IPR = 0; // clear all pending IRQs

  int i;

  for (i=0; i<32; i++) {

    __neorv32_xirq_vector_lut[i] = (uint32_t)(&__neorv32_xirq_dummy_handler);

  }

  // register XIRQ handler in NEORV32 RTE

  return neorv32_rte_exception_install(XIRQ_RTE_ID, __neorv32_xirq_core);

}

/**********************************************************************//**

 * Globally enable XIRQ interrupts (via according FIRQ channel).

 **************************************************************************/

void neorv32_xirq_global_enable(void) {

  // enable XIRQ fast interrupt channel

  neorv32_cpu_irq_enable(XIRQ_FIRQ_ENABLE);

}

/**********************************************************************//**

 * Globally disable XIRQ interrupts (via according FIRQ channel).

 **************************************************************************/

void neorv32_xirq_global_disable(void) {

  // enable XIRQ fast interrupt channel

  neorv32_cpu_irq_disable(XIRQ_FIRQ_ENABLE);

}

/**********************************************************************//**

 * Get number of implemented XIRQ channels

 *

 * @return Number of implemented channels (0..32).

 **************************************************************************/

int neorv32_xirq_get_num(void) {

  uint32_t enable;

  int i, cnt;

  if (neorv32_xirq_available()) {

    neorv32_cpu_irq_disable(XIRQ_FIRQ_ENABLE); // make sure XIRQ cannot fire

    NEORV32_XIRQ.IER = 0xffffffff; // try to set all enable flags

    enable = NEORV32_XIRQ.IER; // read back actually set flags

    // count set bits in enable

    cnt = 0;

    for (i=0; i<32; i++) {

      if (enable & 1) {

        cnt++;

      }

      enable >>= 1;

    }

    return cnt;

  }

  else {

    return 0;

  }

}

/**********************************************************************//**

 * Clear pending interrupt.

 *

 * @param[in] ch XIRQ interrupt channel (0..31).

 **************************************************************************/

void neorv32_xirq_clear_pending(uint8_t ch) {

  if (ch < 32) { // channel valid?

    NEORV32_XIRQ.IPR = ~(1 << ch);

  }

}

/**********************************************************************//**

 * Enable IRQ channel.

 *

 * @param[in] ch XIRQ interrupt channel (0..31).

 **************************************************************************/

void neorv32_xirq_channel_enable(uint8_t ch) {

  if (ch < 32) { // channel valid?

    NEORV32_XIRQ.IER |= 1 << ch;

  }

}

/**********************************************************************//**

 * Disable IRQ channel.

 *

 * @param[in] ch XIRQ interrupt channel (0..31).

 **************************************************************************/

void neorv32_xirq_channel_disable(uint8_t ch) {

  if (ch < 32) { // channel valid?

    NEORV32_XIRQ.IER &= ~(1 << ch);

  }

}

/**********************************************************************//**

 * Install exception handler function for XIRQ channel.

 *

 * @note This will also activate the according XIRQ channel and clear a pending IRQ at this channel.

 *

 * @param[in] ch XIRQ interrupt channel (0..31).

 * @param[in] handler The actual handler function for the specified exception (function MUST be of type "void function(void);").

 * @return 0 if success, 1 if error.

 **************************************************************************/

int neorv32_xirq_install(uint8_t ch, void (*handler)(void)) {

  // channel valid?

  if (ch < 32) {

    __neorv32_xirq_vector_lut[ch] = (uint32_t)handler; // install handler

    uint32_t mask = 1 << ch;

    NEORV32_XIRQ.IPR = ~mask; // clear if pending

    NEORV32_XIRQ.IER |= mask; // enable channel

    return 0;

  }

  return 1;

}

/**********************************************************************//**

 * Uninstall exception handler function for XIRQ channel.

 *

 * @note This will also deactivate the according XIRQ channel and clear pending state.

 *

 * @param[in] ch XIRQ interrupt channel (0..31).

 * @return 0 if success, 1 if error.

 **************************************************************************/

int neorv32_xirq_uninstall(uint8_t ch) {

  // channel valid?

  if (ch < 32) {

    __neorv32_xirq_vector_lut[ch] = (uint32_t)(&__neorv32_xirq_dummy_handler); // override using dummy handler

    uint32_t mask = 1 << ch;

    NEORV32_XIRQ.IER &= ~mask; // disable channel

    NEORV32_XIRQ.IPR = ~mask; // clear if pending

    return 0;

  }

  return 1;

}

/**********************************************************************//**

 * This is the actual second-level (F)IRQ handler for the XIRQ. It will

 * call the previously installed handler if an XIRQ fires.

 **************************************************************************/

static void __attribute__((aligned(16))) __neorv32_xirq_core(void) {

  register uint32_t src = NEORV32_XIRQ.SCR; // get IRQ source (with highest priority)

  uint32_t mask = 1 << src;

  NEORV32_XIRQ.IPR = ~mask; // clear current pending interrupt

  NEORV32_XIRQ.SCR = 0; // acknowledge current interrupt (CPU FIRQ)

  // execute handler

  register uint32_t xirq_handler = __neorv32_xirq_vector_lut[src];

  void (*handler_pnt)(void);

  handler_pnt = (void*)xirq_handler;

  (*handler_pnt)();

}

/**********************************************************************//**

 * XIRQ dummy handler.

 **************************************************************************/

static void __neorv32_xirq_dummy_handler(void) {

  asm volatile ("nop");

}