icoll-imx233.c

void irq_handler(void)
{
    /* save stuff */
    asm volatile(
        "sub    lr, lr, #4               \n" /* Create return address */
        "stmfd  sp!, { r0-r6, r12, lr }  \n" /* Save what gets clobbered */
        "ldr    r0, =0x80000000          \n" /* Read HW_ICOLL_VECTOR  */
        "ldr    r0, [r0]                 \n" /* and notify as side-effect */
        "ldr    r1, =0x8001c290          \n" /* Save pointer to instruction */
        "str    lr, [r1]                 \n" /* in HW_DIGCTL_SCRATCH0 */
        "mrs    r6, spsr                 \n" /* Save SPSR_irq */
        "msr    cpsr_c, #0x13            \n" /* Switch to SVC mode, enable IRQ */
        "mov    r4, lr                   \n" /* Save lr_SVC */
        "and    r5, sp, #4               \n" /* Align SVC stack */
        "sub    sp, sp, r5               \n" /* on 8-byte boundary */
        "blx    _irq_handler             \n" /* Process IRQ, returns ack level */
        "add    sp, sp, r5               \n" /* Undo alignement */
        "mov    lr, r4                   \n" /* Restore lr_SVC */
        "msr    cpsr_c, #0x92            \n" /* Mask IRQ, return to IRQ mode */
        "msr    spsr_cxsf, r6            \n" /* Restore SPSR_irq */
        "mov    r1, #1                   \n" /* Compute ack level value */
        "lsl    r0, r1, r0               \n" /* (1 << ack_lvl) */
        "ldr    r1, =0x80000010          \n" /* Read HW_ICOLL_LEVELACK  */
        "str    r0, [r1]                 \n" /* and write it */
        "ldmfd  sp!, { r0-r6, r12, pc }^ \n" /* Restore regs, and RFE */);
}