AR9331中Linux内核启动中与IRQ中断相关的文件

先列出框架，具体后继再来分析。

 

首先是lds文件，该文件设置了各个section在FLASH或RAM中的先后顺序。

位于~/openwrt1407/build_dir/target-mips_34kc_uClibc-0.9.33.2/linux-ar71xx_generic/linux-3.10.49/arch/mips/kernel/vmlinux.lds

 

另外一个名字相似的，~/openwrt1407/build_dir/target-mips_34kc_uClibc-0.9.33.2/linux-ar71xx_generic/linux-3.10.49/arch/mips/kernel/vmlinux.lds.S

...
#undef mips

#define mips mips

OUTPUT_ARCH(mips)

ENTRY(kernel_entry)

PHDRS {

    text PT_LOAD FLAGS(7);    /* RWX */

    note PT_NOTE FLAGS(4);    /* R__ */

}



#ifdef CONFIG_32BIT

    #ifdef CONFIG_CPU_LITTLE_ENDIAN

        jiffies     = jiffies_64;

    #else

        jiffies     = jiffies_64 + 4;

    #endif

#else

    jiffies     = jiffies_64;

#endif



SECTIONS

{
...

表明入口地址为kernel_entry，该符号在：~/openwrt1407/build_dir/target-mips_34kc_uClibc-0.9.33.2/linux-ar71xx_generic/linux-3.10.49/arch/mips/kernel/head.S中定义

...
NESTED(kernel_entry, 16, sp)            # kernel entry point



    kernel_entry_setup            # cpu specific setup



    setup_c0_status_pri



    /* We might not get launched at the address the kernel is linked to,

       so we jump there.  */

    PTR_LA    t0, 0f

    jr    t0

0:



#ifdef CONFIG_MIPS_MT_SMTC

    /*

     * In SMTC kernel, "CLI" is thread-specific, in TCStatus.

     * We still need to enable interrupts globally in Status,

     * and clear EXL/ERL.

     *

     * TCContext is used to track interrupt levels under

     * service in SMTC kernel. Clear for boot TC before

     * allowing any interrupts.

     */

    mtc0    zero, CP0_TCCONTEXT



    mfc0    t0, CP0_STATUS

    ori    t0, t0, 0xff1f

    xori    t0, t0, 0x001e

    mtc0    t0, CP0_STATUS

#endif /* CONFIG_MIPS_MT_SMTC */



    PTR_LA        t0, __bss_start        # clear .bss

    LONG_S        zero, (t0)

    PTR_LA        t1, __bss_stop - LONGSIZE

1:

    PTR_ADDIU    t0, LONGSIZE

    LONG_S        zero, (t0)

    bne        t0, t1, 1b



    LONG_S        a0, fw_arg0        # firmware arguments

    LONG_S        a1, fw_arg1

    LONG_S        a2, fw_arg2

    LONG_S        a3, fw_arg3



    MTC0        zero, CP0_CONTEXT    # clear context register

    PTR_LA        $28, init_thread_union

    /* Set the SP after an empty pt_regs.  */

    PTR_LI        sp, _THREAD_SIZE - 32 - PT_SIZE

    PTR_ADDU    sp, $28

    back_to_back_c0_hazard

    set_saved_sp    sp, t0, t1

    PTR_SUBU    sp, 4 * SZREG        # init stack pointer



    j        start_kernel

    END(kernel_entry)
...

最终跳到kernel_entry中，该函数在~/openwrt1407/build_dir/target-mips_34kc_uClibc-0.9.33.2/linux-ar71xx_generic/linux-3.10.49/init/main.c中定义：

asmlinkage void __init start_kernel(void)

{

    char * command_line;

    extern const struct kernel_param __start___param[], __stop___param[];



    /*

     * Need to run as early as possible, to initialize the

     * lockdep hash:

     */

    lockdep_init();

    smp_setup_processor_id();

    debug_objects_early_init();



    /*

     * Set up the the initial canary ASAP:

     */

    boot_init_stack_canary();



    cgroup_init_early();



    local_irq_disable();

    early_boot_irqs_disabled = true;



/*

 * Interrupts are still disabled. Do necessary setups, then

 * enable them

 */

    boot_cpu_init();

    page_address_init();

    pr_notice("%s", linux_banner);

    setup_arch(&command_line);

    mm_init_owner(&init_mm, &init_task);

    mm_init_cpumask(&init_mm);

    setup_command_line(command_line);

    setup_nr_cpu_ids();

    setup_per_cpu_areas();

    smp_prepare_boot_cpu();    /* arch-specific boot-cpu hooks */



    build_all_zonelists(NULL, NULL);

    page_alloc_init();



    pr_notice("Kernel command line: %s\n", boot_command_line);

    parse_early_param();

    parse_args("Booting kernel", static_command_line, __start___param,

           __stop___param - __start___param,

           -1, -1, &unknown_bootoption);



    jump_label_init();



    /*

     * These use large bootmem allocations and must precede

     * kmem_cache_init()

     */

    setup_log_buf(0);

    pidhash_init();

    vfs_caches_init_early();

    sort_main_extable();

    trap_init();

    mm_init();



    /*

     * Set up the scheduler prior starting any interrupts (such as the

     * timer interrupt). Full topology setup happens at smp_init()

     * time - but meanwhile we still have a functioning scheduler.

     */

    sched_init();

    /*

     * Disable preemption - early bootup scheduling is extremely

     * fragile until we cpu_idle() for the first time.

     */

    preempt_disable();

    if (WARN(!irqs_disabled(), "Interrupts were enabled *very* early, fixing it\n"))

        local_irq_disable();

    idr_init_cache();

    perf_event_init();

    rcu_init();

    tick_nohz_init();

    radix_tree_init();

    /* init some links before init_ISA_irqs() */ early_irq_init();

    init_IRQ();

    tick_init();

    init_timers();

    hrtimers_init();

    softirq_init();

    timekeeping_init();

    time_init();

    profile_init();

    call_function_init();

    WARN(!irqs_disabled(), "Interrupts were enabled early\n");

    early_boot_irqs_disabled = false;

    local_irq_enable();



    kmem_cache_init_late();



    /*

     * HACK ALERT! This is early. We're enabling the console before

     * we've done PCI setups etc, and console_init() must be aware of

     * this. But we do want output early, in case something goes wrong.

     */

    console_init();

    if (panic_later)

        panic(panic_later, panic_param);



    lockdep_info();



    /*

     * Need to run this when irqs are enabled, because it wants

     * to self-test [hard/soft]-irqs on/off lock inversion bugs

     * too:

     */

    locking_selftest();



#ifdef CONFIG_BLK_DEV_INITRD

    if (initrd_start && !initrd_below_start_ok &&

        page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {

        pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n",

            page_to_pfn(virt_to_page((void *)initrd_start)),

            min_low_pfn);

        initrd_start = 0;

    }

#endif

    page_cgroup_init();

    debug_objects_mem_init();

    kmemleak_init();

    setup_per_cpu_pageset();

    numa_policy_init();

    if (late_time_init)

        late_time_init();

    sched_clock_init();

    calibrate_delay();

    pidmap_init();

    anon_vma_init();

#ifdef CONFIG_X86

    if (efi_enabled(EFI_RUNTIME_SERVICES))

        efi_enter_virtual_mode();

#endif

    thread_info_cache_init();

    cred_init();

    fork_init(totalram_pages);

    proc_caches_init();

    buffer_init();

    key_init();

    security_init();

    dbg_late_init();

    vfs_caches_init(totalram_pages);

    signals_init();

    /* rootfs populating might need page-writeback */

    page_writeback_init();

#ifdef CONFIG_PROC_FS

    proc_root_init();

#endif

    cgroup_init();

    cpuset_init();

    taskstats_init_early();

    delayacct_init();



    check_bugs();



    acpi_early_init(); /* before LAPIC and SMP init */

    sfi_init_late();



    if (efi_enabled(EFI_RUNTIME_SERVICES)) {

        efi_late_init();

        efi_free_boot_services();

    }



    ftrace_init();



    /* Do the rest non-__init'ed, we're now alive */

    rest_init();

}

上面调用了两个IRQ初始化函数early_irq_init和init_IRQ，分别在~/openwrt1407/build_dir/target-mips_34kc_uClibc-0.9.33.2/linux-ar71xx_generic/linux-3.10.49/kernel/irq/irqdesc.c和~/openwrt1407/build_dir/target-mips_34kc_uClibc-0.9.33.2/linux-ar71xx_generic/linux-3.10.49/arch/mips/kernel/irq.c中。

early_irq_init函数

int __init early_irq_init(void)

{

    int i, initcnt, node = first_online_node;

    struct irq_desc *desc;



    init_irq_default_affinity();



    /* Let arch update nr_irqs and return the nr of preallocated irqs */

    initcnt = arch_probe_nr_irqs();

    printk(KERN_INFO "NR_IRQS:%d nr_irqs:%d %d\n", NR_IRQS, nr_irqs, initcnt);



    if (WARN_ON(nr_irqs > IRQ_BITMAP_BITS))

        nr_irqs = IRQ_BITMAP_BITS;



    if (WARN_ON(initcnt > IRQ_BITMAP_BITS))

        initcnt = IRQ_BITMAP_BITS;



    if (initcnt > nr_irqs)

        nr_irqs = initcnt;



    for (i = 0; i < initcnt; i++) {

        desc = alloc_desc(i, node, NULL);

        set_bit(i, allocated_irqs);

        irq_insert_desc(i, desc);

    }

    return arch_early_irq_init();

}

init_IRQ函数

void __init init_IRQ(void)

{

    int i;



#ifdef CONFIG_KGDB

    if (kgdb_early_setup)

        return;

#endif



    for (i = 0; i < NR_IRQS; i++)

        irq_set_noprobe(i);



    arch_init_irq();



#ifdef CONFIG_KGDB

    if (!kgdb_early_setup)

        kgdb_early_setup = 1;

#endif

}

上面调用的arch_init_irq函数位于~/openwrt1407/build_dir/target-mips_34kc_uClibc-0.9.33.2/linux-ar71xx_generic/linux-3.10.49/arch/mips/ath79/irq.c中

arch_init_irq函数

static void __init ath79_misc_irq_init(void)

{

    void __iomem *base = ath79_reset_base;

    int i;



    __raw_writel(0, base + AR71XX_RESET_REG_MISC_INT_ENABLE);

    __raw_writel(0, base + AR71XX_RESET_REG_MISC_INT_STATUS);



    if (soc_is_ar71xx() || soc_is_ar913x())

        ath79_misc_irq_chip.irq_mask_ack = ar71xx_misc_irq_mask;

    else if (soc_is_ar724x() ||

         soc_is_ar933x() ||

         soc_is_ar934x() ||

         soc_is_qca953x() ||

         soc_is_qca955x())

        ath79_misc_irq_chip.irq_ack = ar724x_misc_irq_ack;

    else

        BUG();



    for (i = ATH79_MISC_IRQ_BASE;

         i < ATH79_MISC_IRQ_BASE + ATH79_MISC_IRQ_COUNT; i++) {

        irq_set_chip_and_handler(i, &ath79_misc_irq_chip,

                     handle_level_irq);

    }



    irq_set_chained_handler(ATH79_CPU_IRQ(6), ath79_misc_irq_handler);

}


...


void __init arch_init_irq(void)

{

    if (soc_is_ar71xx()) {

        ath79_ip2_handler = ar71xx_ip2_handler;

        ath79_ip3_handler = ar71xx_ip3_handler;

    } else if (soc_is_ar724x()) {

        ath79_ip2_handler = ar724x_ip2_handler;

        ath79_ip3_handler = ar724x_ip3_handler;

    } else if (soc_is_ar913x()) {

        ath79_ip2_handler = ar913x_ip2_handler;

        ath79_ip3_handler = ar913x_ip3_handler;

    } else if (soc_is_ar933x()) {

        ath79_ip2_handler = ar933x_ip2_handler;

        ath79_ip3_handler = ar933x_ip3_handler;

    } else if (soc_is_ar934x()) {

        ath79_ip2_handler = ath79_default_ip2_handler;

        ath79_ip3_handler = ar934x_ip3_handler;

    } else if (soc_is_qca953x()) {

        ath79_ip2_handler = ath79_default_ip2_handler;

        ath79_ip3_handler = ath79_default_ip3_handler;

    } else if (soc_is_qca955x()) {

        ath79_ip2_handler = ath79_default_ip2_handler;

        ath79_ip3_handler = ath79_default_ip3_handler;

    } else {

        BUG();

    }



    cp0_perfcount_irq = ATH79_MISC_IRQ(5);

    mips_cpu_irq_init();

    ath79_misc_irq_init();



    if (soc_is_ar934x())

        ar934x_ip2_irq_init();

    else if (soc_is_qca955x())

        qca955x_irq_init();

}

mips_cpu_irq_init函数位于~/openwrt1407/build_dir/target-mips_34kc_uClibc-0.9.33.2/linux-ar71xx_generic/linux-3.10.49/arch/mips/kernel/irq_cpu.c中，ath79_misc_irq_init同在irq.c文件中。

void __init mips_cpu_irq_init(void)

{

    int irq_base = MIPS_CPU_IRQ_BASE;

    int i;



    /* Mask interrupts. */

    clear_c0_status(ST0_IM);

    clear_c0_cause(CAUSEF_IP);



    /* Software interrupts are used for MT/CMT IPI */

    for (i = irq_base; i < irq_base + 2; i++)

        irq_set_chip_and_handler(i, cpu_has_mipsmt ?

                     &mips_mt_cpu_irq_controller :

                     &mips_cpu_irq_controller,

                     handle_percpu_irq);



    for (i = irq_base + 2; i < irq_base + 8; i++)

        irq_set_chip_and_handler(i, &mips_cpu_irq_controller,

                     handle_percpu_irq);

}