GIC_controller.c

/*
* Configure the Generic Interrupt Controller (GIC)
*/
void config_GIC(void) {
    
    // configure the PS2 port (Interrupt ID = 79)
    config_interrupt(PS2_IRQ, CPU0);
    
    // configure the A9 Private timer (Interrupt ID = 29)
    config_interrupt(MPCORE_PRIV_TIMER_IRQ, CPU0);
    
    // Set Interrupt Priority Mask Register (ICCPMR). Enable interrupts of all priorities
    *((int *) MPCORE_GIC_CPUIF + ICCICR) = 0xFFFF;
    
    // Set CPU Interface Control Register (ICCICR). Enable signaling of interrupts
    *((int *) MPCORE_GIC_CPUIF + ICCICR) = 0x1;
    
    // Configure the Distributor Control Register (ICDDCR) to send pending interrupts to CPUs
    *((int *) MPCORE_GIC_DIST + ICDDCR) = 0x1;
}

/*
* Configure Set Enable Registers (ICDISERn) and Interrupt Processor Target Registers (ICDIPTRn).
* The default (reset) values are used for other registers in the GIC.
*/
void config_interrupt (int N, int CPU_target) {
    
    // Initialize variables
    int reg_offset, index, value, address;
    
    // Configure the Interrupt Set-Enable Registers (ICDISERn).
    // reg_offset = integer_div(N / 32) * 4
    reg_offset = (N >> 3) & ~0x3;
    address = MPCORE_GIC_DIST + ICDISER + reg_offset;
    
    // value = 1 << (N mod 32)
    index = N & 0x1F;
    value = 0x1 << index;
    
    // Set the bit
    *(int *) address |= value;
    
    
    // Configure the Interrupt Processor Targets Register (ICDIPTRn)
    // reg_offset = integer_div(N / 4) * 4
    reg_offset = N & ~0x3;
    
    // index = N mod 4
    index = N & 0x3;
    
    // get address
    address = MPCORE_GIC_DIST + ICDIPTR + reg_offset + index;
    
    /* Now that we know the register address and value, write to (only) the appropriate byte */
    *(char *) address = (char) CPU_target;
}

// Configure the ps2 mouse interrupt
void config_ps2_mouse() {
    // Enable the ps2 interrupt
    volatile int *ps2_status_ptr = (int *) (PS2_BASE + 0x4);
    *ps2_status_ptr = 0x1;
}

// Configure the timer interrupt
void config_private_timer() {
    volatile int *timer_base_ptr = (int *) MPCORE_PRIV_TIMER;
    volatile int *timer_load_ptr = timer_base_ptr;
    volatile int *timer_ctrl_ptr = timer_base_ptr + 0x2;
    volatile int *timer_acknowledge_ptr = timer_base_ptr + 0x3;
    
    // Load the private timer value, 0.25s per interrupt
    *timer_load_ptr = TIMER_LOAD_VAL;
    // Turn on auto and interrupt enable
    *timer_ctrl_ptr = 0x7;
    // Clear interrupt register
    *timer_acknowledge_ptr = 0x1;
}