AM335X StarterWare 自带bootloader对IRQ的处理

来源：互联网发布：优化神马pc关键词排名编辑：程序博客网时间：2024/06/05 01:59

IRQHandler:
        SUB      r14, r14, #4             @ Apply lr correction
        STMFD    r13!, {r0-r3, r12, r14} @ Save context
        MRS      r12, spsr                @ Copy spsr
        VMRS     r1, FPSCR                @ Copy fpscr
        STMFD    r13!, {r1, r12}          @ Save spsr and fpscr
        VSTMDB   r13!, {d0-d7}            @ Save D0-D7 NEON/VFP registers

        LDR      r0, =ADDR_THRESHOLD      @ Get the IRQ Threshold
        LDR      r1, [r0, #0]
        STMFD    r13!, {r1}               @ Save the threshold value

        LDR      r2, =ADDR_IRQ_PRIORITY   @ Get the active IRQ priority
        LDR      r3, [r2, #0]
        STR      r3, [r0, #0]             @ Set the priority as threshold

        LDR      r1, =ADDR_SIR_IRQ        @ Get the Active IRQ
        LDR      r2, [r1]
        AND      r2, r2, #MASK_ACTIVE_IRQ @ Mask the Active IRQ number

        MOV      r0, #NEWIRQAGR           @ To enable new IRQ Generation
        LDR      r1, =ADDR_CONTROL

        CMP      r3, #0                   @ Check if non-maskable priority 0
        STRNE    r0, [r1]                 @ if > 0 priority, acknowledge INTC
        DSB                               @ Make sure acknowledgement is completed

        @
        @ Enable IRQ and switch to system mode. But IRQ shall be enabled
        @ only if priority level is > 0. Note that priority 0 is non maskable.
        @ Interrupt Service Routines will execute in System Mode.
        @
        MRS      r14, cpsr                @ Read cpsr
        ORR      r14, r14, #MODE_SYS
        BICNE    r14, r14, #I_BIT         @ Enable IRQ if priority > 0
        MSR      cpsr, r14


        STMFD    r13!, {r14}              @ Save lr_usr

        LDR      r0, =fnRAMVectors        @ Load the base of the vector table
        ADD      r14, pc, #0              @ Save return address in LR
        LDR      pc, [r0, r2, lsl #2]     @ Jump to the ISR

        LDMFD    r13!, {r14}              @ Restore lr_usr

        @
        @ Disable IRQ and change back to IRQ mode
        @
        CPSID    i, #MODE_IRQ

        LDR      r0, =ADDR_THRESHOLD      @ Get the IRQ Threshold

        LDR      r1, [r0, #0]
        CMP      r1, #0                   @ If priority 0
        MOVEQ    r2, #NEWIRQAGR           @ Enable new IRQ Generation
        LDREQ    r1, =ADDR_CONTROL
        STREQ    r2, [r1]

        LDMFD    r13!, {r1}
        STR      r1, [r0, #0]             @ Restore the threshold value
        VLDMIA   r13!, {d0-d7}            @ Restore D0-D7 Neon/VFP registers
        LDMFD    r13!, {r1, r12}          @ Get fpscr and spsr
        MSR      spsr, r12                @ Restore spsr
        VMSR     fpscr, r1                @ Restore fpscr

        LDMFD    r13!, {r0-r3, r12, pc}^ @ Restore the context and return

0 0