neorv32/sw/example/demo_xirq/main.c

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// #################################################################################################
// # << NEORV32 - External Interrupt Controller (XIRQ) Demo Program >> #
// # ********************************************************************************************* #
// # BSD 3-Clause License #
// # #
// # Copyright (c) 2023, Stephan Nolting. All rights reserved. #
// # #
// # Redistribution and use in source and binary forms, with or without modification, are #
// # permitted provided that the following conditions are met: #
// # #
// # 1. Redistributions of source code must retain the above copyright notice, this list of #
// # conditions and the following disclaimer. #
// # #
// # 2. Redistributions in binary form must reproduce the above copyright notice, this list of #
// # conditions and the following disclaimer in the documentation and/or other materials #
// # provided with the distribution. #
// # #
// # 3. Neither the name of the copyright holder nor the names of its contributors may be used to #
// # endorse or promote products derived from this software without specific prior written #
// # permission. #
// # #
// # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS #
// # OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF #
// # MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE #
// # COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, #
// # EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE #
// # GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED #
// # AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING #
// # NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED #
// # OF THE POSSIBILITY OF SUCH DAMAGE. #
// # ********************************************************************************************* #
// # The NEORV32 Processor - https://github.com/stnolting/neorv32 (c) Stephan Nolting #
// #################################################################################################
/**********************************************************************//**
* @file demo_xirq/main.c
* @author Stephan Nolting
* @brief External interrupt controller (XIRQ) demo program (using hardware-assisted prioritization).
**************************************************************************/
#include <neorv32.h>
/**********************************************************************//**
* @name User configuration
**************************************************************************/
/**@{*/
/** UART BAUD rate */
#define BAUD_RATE 19200
/**@}*/
/**********************************************************************//**
* XIRQ handler channel 0.
* @warning This function has to be of type "void xyz(void)" and must not use any interrupt attributes!
**************************************************************************/
void xirq_handler_ch0(void) {
neorv32_uart0_printf("XIRQ interrupt from channel %i\n", 0);
}
/**********************************************************************//**
* XIRQ handler channel 1.
* @warning This function has to be of type "void xyz(void)" and must not use any interrupt attributes!
**************************************************************************/
void xirq_handler_ch1(void) {
neorv32_uart0_printf("XIRQ interrupt from channel %i\n", 1);
}
/**********************************************************************//**
* XIRQ handler channel 2.
* @warning This function has to be of type "void xyz(void)" and must not use any interrupt attributes!
**************************************************************************/
void xirq_handler_ch2(void) {
neorv32_uart0_printf("XIRQ interrupt from channel %i\n", 2);
}
/**********************************************************************//**
* XIRQ handler channel 3.
* @warning This function has to be of type "void xyz(void)" and must not use any interrupt attributes!
**************************************************************************/
void xirq_handler_ch3(void) {
neorv32_uart0_printf("XIRQ interrupt from channel %i\n", 3);
}
/**********************************************************************//**
* Main function
*
* @note This program requires the XIRQ and the UART to be synthesized.
*
* @return 0 if execution was successful
**************************************************************************/
int main() {
// initialize the neorv32 runtime environment
// this will take care of handling all CPU traps
neorv32_rte_setup();
// setup UART at default baud rate, no interrupts
neorv32_uart0_setup(BAUD_RATE, 0);
// check if XIRQ unit is implemented at all
if (neorv32_xirq_available() == 0) {
neorv32_uart0_printf("XIRQ not synthesized!\n");
return 1;
}
// intro
neorv32_uart0_printf("<< External Interrupts Controller (XIRQ) Demo Program >>\n\n");
int err_cnt = 0;
// initialize XIRQ controller
// this will disable all XIRQ channels and will also clear any pending external interrupts
// (details: this will register the XIRQ's second-level interrupt handler in the NEORV32 RTE)
err_cnt = neorv32_xirq_setup();
// check if setup went fine
if (err_cnt) {
neorv32_uart0_printf("Error during XIRQ setup!\n");
return 1;
}
// install handler functions for XIRQ channel 0,1,2,3. note that these functions are "normal" functions!
// (details: these are "third-level" interrupt handlers)
// neorv32_xirq_install() also enables the specified XIRQ channel and clears any pending interrupts
err_cnt = 0;
err_cnt += neorv32_xirq_install(0, xirq_handler_ch0); // handler function for channel 0
err_cnt += neorv32_xirq_install(1, xirq_handler_ch1); // handler function for channel 1
err_cnt += neorv32_xirq_install(2, xirq_handler_ch2); // handler function for channel 2
err_cnt += neorv32_xirq_install(3, xirq_handler_ch3); // handler function for channel 3
// check if installation went fine
if (err_cnt) {
neorv32_uart0_printf("Error during XIRQ install!\n");
return 1;
}
// allow XIRQ to trigger CPU interrupt
neorv32_xirq_global_enable();
// enable machine-mode interrupts
neorv32_cpu_csr_set(CSR_MSTATUS, 1 << CSR_MSTATUS_MIE);
// the code below assumes the XIRQ inputs are connected to the processor's GPIO output port
// so we can trigger the IRQs from software; if you have connected the XIRQs to buttons you
// can remove the code below (note the trigger configuration using the XIRQ generics!)
{
neorv32_uart0_printf("Triggering XIRQs...\n");
// trigger XIRQs 3:0 at once
// assumes xirq_i(31:0) <= gpio.output(31:0)
// due to the prioritization this will execute
// 1. xirq_handler_ch0
// 2. xirq_handler_ch1
// 3. xirq_handler_ch2
// 4. xirq_handler_ch3
neorv32_gpio_port_set(0xF); // set output pins 3:0 -> trigger XIRQ 3:0
neorv32_gpio_port_set(0x0);
}
// All incoming XIRQ interrupt requests are "prioritized" in this example. The XIRQ FIRQ handler
// reads the ID of the interrupt with the highest priority from the XIRQ controller ("source" register) and calls the according
// handler function (installed via neorv32_xirq_install();).
// Non-prioritized handling of interrupts (or custom prioritization) can be implemented by manually reading the
// XIRQ controller's "pending" register. Then it is up to the software to define which pending IRQ should be serviced first.
asm volatile ("nop");
asm volatile ("nop");
asm volatile ("nop");
asm volatile ("nop");
// just as an example: to disable certain XIRQ interrupt channels, we can
// un-install the according handler. this will also clear a pending interrupt for that channel
neorv32_xirq_uninstall(0); // disable XIRQ channel 0 and remove associated handler
neorv32_xirq_uninstall(1); // disable XIRQ channel 1 and remove associated handler
neorv32_xirq_uninstall(2); // disable XIRQ channel 2 and remove associated handler
neorv32_xirq_uninstall(3); // disable XIRQ channel 3 and remove associated handler
// you can also manually clear pending interrupts
neorv32_xirq_clear_pending(0); // clear pending interrupt of channel 0
// manually enable and disable XIRQ channels
neorv32_xirq_channel_enable(0); // enable channel 0
neorv32_xirq_channel_disable(0); // disable channel 0
// globally enable/disable XIRQ CPU interrupt
// this will not affect the XIRQ configuration / pending interrupts
neorv32_xirq_global_enable();
neorv32_xirq_global_disable();
neorv32_uart0_printf("Program completed.\n");
return 0;
}