diff options
Diffstat (limited to 'software/demo_gpio/demo_gpio.c')
| -rw-r--r-- | software/demo_gpio/demo_gpio.c | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/software/demo_gpio/demo_gpio.c b/software/demo_gpio/demo_gpio.c new file mode 100644 index 0000000..3b0b6f5 --- /dev/null +++ b/software/demo_gpio/demo_gpio.c @@ -0,0 +1,182 @@ +// See LICENSE for license details. + +#include <stdio.h> + +#include "shared.h" +#include "plic.h" +#include <string.h> + +void reset_demo (void); + +// Structures for registering different interrupt handlers +// for different parts of the application. +typedef void (*function_ptr_t) (void); + +void no_interrupt_handler (void) {}; + +function_ptr_t g_ext_interrupt_handlers[9]; + +function_ptr_t g_m_timer_interrupt_handler = no_interrupt_handler; + +// Instance data for the PLIC. + +plic_instance_t g_plic; + +// Simple variables for LEDs, buttons, etc. +volatile unsigned int* g_outputs = (unsigned int *) (GPIO_BASE_ADDR + GPIO_OUT_OFFSET); +volatile unsigned int* g_inputs = (unsigned int *) (GPIO_BASE_ADDR + GPIO_IN_OFFSET); +volatile unsigned int* g_tristates = (unsigned int *) (GPIO_BASE_ADDR + GPIO_TRI_OFFSET); + + +/*Entry Point for PLIC Interrupt Handler*/ +void handle_m_ext_interrupt(){ + plic_source int_num = PLIC_claim_interrupt(&g_plic); + if ((int_num >=1 ) && (int_num <= 8)) { + g_ext_interrupt_handlers[int_num](); + } + else { + _exit(1 + (uintptr_t) int_num); + } + PLIC_complete_interrupt(&g_plic, int_num); +} + + +/*Entry Point for Machine Timer Interrupt Handler*/ +void handle_m_time_interrupt(){ + + clear_csr(mie, MIP_MTIP); + + // Reset the timer for 3s in the future. + // This also clears the existing timer interrupt. + + volatile uint64_t * mtime = (uint64_t*) MTIME_ADDR; + volatile uint64_t * mtimecmp = (uint64_t*) MTIMECMP_BASE_ADDR; + uint64_t now = *mtime; + uint64_t then = now + 3 * CLOCK_FREQUENCY / RTC_PRESCALER; + *mtimecmp = then; + + // read the current value of the LEDS and invert them. + uint32_t leds = *g_outputs; + + *g_outputs = (~leds) & ((0xF << RED_LEDS_OFFSET) | + (0xF << GREEN_LEDS_OFFSET) | + (0xF << BLUE_LEDS_OFFSET)); + + + // Re-enable the timer interrupt. + set_csr(mie, MIP_MTIP); + +} + + +/*Entry Point for Machine Timer Interrupt Handler*/ +void handle_m_timer_interrupt(){ + g_m_timer_interrupt_handler(); +} + +const char * instructions_msg = " \ +\n\ + SIFIVE, INC.\n\ +\n\ + 5555555555555555555555555\n\ + 5555 5555\n\ + 5555 5555\n\ + 5555 5555\n\ + 5555 5555555555555555555555\n\ + 5555 555555555555555555555555\n\ + 5555 5555\n\ + 5555 5555\n\ + 5555 5555\n\ +5555555555555555555555555555 55555\n\ + 55555 555555555 55555\n\ + 55555 55555 55555\n\ + 55555 5 55555\n\ + 55555 55555\n\ + 55555 55555\n\ + 55555 55555\n\ + 55555 55555\n\ + 55555 55555\n\ + 555555555\n\ + 55555\n\ + 5\n\ +\n\ + SiFive E-Series Coreplex Demo on Arty Board\n \ + \n\ + "; + +void print_instructions() { + + write (STDOUT_FILENO, instructions_msg, strlen(instructions_msg)); + +} + +void button_0_handler(void) { + + // Rainbow LEDs! + * g_outputs = (0x9 << RED_LEDS_OFFSET) | (0xA << GREEN_LEDS_OFFSET) | (0xC << BLUE_LEDS_OFFSET); + +}; + + +void reset_demo (){ + + // Disable the machine & timer interrupts until setup is done. + + clear_csr(mie, MIP_MEIP); + clear_csr(mie, MIP_MTIP); + + g_ext_interrupt_handlers[INT_DEVICE_BUTTON_0] = button_0_handler; + g_ext_interrupt_handlers[INT_DEVICE_BUTTON_1] = no_interrupt_handler; + g_ext_interrupt_handlers[INT_DEVICE_BUTTON_2] = no_interrupt_handler; + g_ext_interrupt_handlers[INT_DEVICE_BUTTON_3] = no_interrupt_handler; + g_ext_interrupt_handlers[INT_DEVICE_JA_7] = no_interrupt_handler; + g_ext_interrupt_handlers[INT_DEVICE_JA_8] = no_interrupt_handler; + g_ext_interrupt_handlers[INT_DEVICE_JA_9] = no_interrupt_handler; + g_ext_interrupt_handlers[INT_DEVICE_JA_10] = no_interrupt_handler; + + print_instructions(); + + PLIC_enable_interrupt (&g_plic, INT_DEVICE_BUTTON_0); + + // Set the machine timer to go off in 3 seconds. + // The + volatile uint64_t * mtime = (uint64_t*) MTIME_ADDR; + volatile uint64_t * mtimecmp = (uint64_t*) MTIMECMP_BASE_ADDR; + uint64_t now = *mtime; + uint64_t then = now + 3*CLOCK_FREQUENCY / RTC_PRESCALER; + *mtimecmp = then; + + // Enable the Machine-External bit in MIE + set_csr(mie, MIP_MEIP); + + // Enable the Machine-Timer bit in MIE + set_csr(mie, MIP_MTIP); + + // Enable interrupts in general. + set_csr(mstatus, MSTATUS_MIE); + +} + +int main(int argc, char **argv) +{ + // Set up the GPIOs such that the inputs' tristate are set. + // The boot ROM actually does this, but still good. + + * g_tristates = (0xF << BUTTONS_OFFSET) | (0xF << SWITCHES_OFFSET) | (0xF << JA_IN_OFFSET); + + * g_outputs = (0xF << RED_LEDS_OFFSET); + + + /************************************************************************** + * Set up the PLIC + * + *************************************************************************/ + PLIC_init(&g_plic, PLIC_BASE_ADDR, PLIC_NUM_SOURCES, PLIC_NUM_PRIORITIES); + + reset_demo(); + + while (1); + + return 0; + +} |