中断二
依然从start_kernel开始,里面调用了四个涉及中断的函数，如下：
1、trap_init();
2、early_trap_init();
3、init_IRQ();
4、softirq_init();
下面来一个一个分析
1、trap_init()
arch/arm/kernel/trap.c
void __init trap_init(void)
{
return;
}
貌似在arm的架构下没什么好说的
2、early_irq_init();
arch/arm/kernel/trap.c
void __init early_trap_init(void)
{
unsigned long vectors = CONFIG_VECTORS_BASE;
extern char __stubs_start[], __stubs_end[];
extern char __vectors_start[], __vectors_end[];
extern char __kuser_helper_start[], __kuser_helper_end[];
int kuser_sz = __kuser_helper_end - __kuser_helper_start;
/*
* Copy the vectors, stubs and kuser helpers (in entry-armv.S)
* into the vector page, mapped at 0xffff0000, and ensure these
* are visible to the instruction stream.
*/
memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
memcpy((void *)vectors + 0x200, __stubs_start, __stubs_end - __stubs_start);
memcpy((void *)vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
/*
* Copy signal return handlers into the vector page, and
* set sigreturn to be a pointer to these.
*/
memcpy((void *)KERN_SIGRETURN_CODE, sigreturn_codes,
sizeof(sigreturn_codes));
flush_icache_range(vectors, vectors + PAGE_SIZE);
modify_domain(DOMAIN_USER, DOMAIN_CLIENT);
}
3、init_IRQ();
arch/arm/kernel/irq.c
void __init init_IRQ(void)
{
int irq;
for (irq = 0; irq < NR_IRQS; irq++)
irq_desc[irq].status |= IRQ_NOREQUEST | IRQ_NOPROBE;
init_arch_irq(); //分析到处，他妈的又差点把我给骗了此处在start_kernel中的setup_arch里将machine start里的init_irq传递到此的,此为函数指针
}
MACHINE_START(MX51_3DS, "Freescale MX51 3-Stack Board")
/* Maintainer: Freescale Semiconductor, Inc. */
.phys_io = AIPS1_BASE_ADDR,
.io_pg_offst = ((AIPS1_BASE_ADDR_VIRT) >> 18) & 0xfffc,
.fixup = fixup_mxc_board,
.map_io = mx5_map_io,
.init_irq = mx5_init_irq,
.init_machine = mxc_board_init,
.timer = &mxc_timer,
MACHINE_END
arch/arm/mach-mx5/device.c
void __init mx5_init_irq(void)
{
unsigned long tzic_addr;
if (cpu_is_mx51_rev(CHIP_REV_2_0) < 0)
tzic_addr = MX51_TZIC_BASE_ADDR_T01;
else if (cpu_is_mx51_rev(CHIP_REV_2_0) > 0)
tzic_addr = MX51_TZIC_BASE_ADDR;
else /* mx53 and mx50 */
tzic_addr = MX53_TZIC_BASE_ADDR;
mxc_tzic_init_irq(tzic_addr);
}
arch/arm/plat-mxc/tzic.c
void __init mxc_tzic_init_irq(unsigned long base)
{
int i;
tzic_base = ioremap(base, SZ_4K);
/* put the TZIC into the reset value with
* all interrupts disabled
*/
i = __raw_readl(TZIC_INTCNTL);
__raw_writel(0x80010001, TZIC_INTCNTL);
i = __raw_readl(TZIC_INTCNTL);
__raw_writel(0x1f, TZIC_PRIOMASK);
i = __raw_readl(TZIC_PRIOMASK);
__raw_writel(0x02, TZIC_SYNCCTRL);
i = __raw_readl(TZIC_SYNCCTRL);
for (i = 0; i < 4; i++) {
__raw_writel(0xFFFFFFFF, TZIC_INTSEC0 + i * 4);
}
/* disable all interrupts */
for (i = 0; i < 4; i++) {
__raw_writel(0xFFFFFFFF, TZIC_ENCLEAR0 + i * 4);
}
/* all IRQ no FIQ Warning :: No selection */
for (i = 0; i < TZIC_NUM_IRQS; i++) {
set_irq_chip(i, &mxc_tzic_chip);
set_irq_handler(i, handle_level_irq);
set_irq_flags(i, IRQF_VALID);
}
printk(KERN_INFO "MXC IRQ initialized\n");
}
kernel/irq/chip.c
int set_irq_chip(unsigned int irq, struct irq_chip *chip)
{
struct irq_desc *desc = irq_to_desc(irq);
unsigned long flags;
if (!desc) {
WARN(1, KERN_ERR "Trying to install chip for IRQ%d\n", irq);
return -EINVAL;
}
if (!chip)
chip = &no_irq_chip;
spin_lock_irqsave(&desc->lock, flags);
irq_chip_set_defaults(chip);
desc->chip = chip;
spin_unlock_irqrestore(&desc->lock, flags);
return 0;
}
kernel/irq/handle.c
struct irq_chip no_irq_chip = {
.name = "none",
.startup = noop_ret,
.shutdown = noop,
.enable = noop,
.disable = noop,
.ack = ack_bad,
.end = noop,
};
/include/linux/irq.h
static inline void
set_irq_handler(unsigned int irq, irq_flow_handler_t handle)
{
__set_irq_handler(irq, handle, 0, NULL);
}
/kernel/irq/chip.c
void
__set_irq_handler(unsigned int irq, irq_flow_handler_t handle, int is_chained,
const char *name)
{
struct irq_desc *desc = irq_to_desc(irq);
unsigned long flags;
if (!desc) {
printk(KERN_ERR
"Trying to install type control for IRQ%d\n", irq);
return;
}
if (!handle)
handle = handle_bad_irq;
else if (desc->chip == &no_irq_chip) {
printk(KERN_WARNING "Trying to install %sinterrupt handler "
"for IRQ%d\n", is_chained ? "chained " : "", irq);
/*
* Some ARM implementations install a handler for really dumb
* interrupt hardware without setting an irq_chip. This worked
* with the ARM no_irq_chip but the check in setup_irq would
* prevent us to setup the interrupt at all. Switch it to
* dummy_irq_chip for easy transition.
*/
desc->chip = &dummy_irq_chip;
}
spin_lock_irqsave(&desc->lock, flags);
/* Uninstall? */
if (handle == handle_bad_irq) {
if (desc->chip != &no_irq_chip)
mask_ack_irq(desc, irq);
desc->status |= IRQ_DISABLED;
desc->depth = 1;
}
desc->handle_irq = handle;
desc->name = name;
if (handle != handle_bad_irq && is_chained) {
desc->status &= ~IRQ_DISABLED;
desc->status |= IRQ_NOREQUEST | IRQ_NOPROBE;
desc->depth = 0;
desc->chip->startup(irq);
}
spin_unlock_irqrestore(&desc->lock, flags);
}
至此，貌似中断以初始化完毕
再看一下softirq_init();
kernel/softirq.c
void __init softirq_init(void)
{
int cpu;
for_each_possible_cpu(cpu) {
int i;
per_cpu(tasklet_vec, cpu).tail =
&per_cpu(tasklet_vec, cpu).head;
per_cpu(tasklet_hi_vec, cpu).tail =
&per_cpu(tasklet_hi_vec, cpu).head;
for (i = 0; i < NR_SOFTIRQS; i++)
INIT_LIST_HEAD(&per_cpu(softirq_work_list[i], cpu));
}
register_hotcpu_notifier(&remote_softirq_cpu_notifier);
open_softirq(TASKLET_SOFTIRQ, tasklet_action);
open_softirq(HI_SOFTIRQ, tasklet_hi_action);
}
/include/linux/interrupt.h
struct tasklet_struct
{
struct tasklet_struct *next;
unsigned long state;
atomic_t count;
void (*func)(unsigned long);
unsigned long data;
};
#define DECLARE_TASKLET(name, func, data) \
struct tasklet_struct name = { NULL, 0, ATOMIC_INIT(0), func, data};
#define DECLARE_TASKLET_DISABLED(name, func, data) \
struct tasklet_struct name = { NULL, 0, ATOMIC_INIT(1), func, data }
enum //软中断类型
{
HI_SOFTIRQ=0,
TIMER_SOFTIRQ,
NET_TX_SOFTIRQ,
NET_RX_SOFTIRQ,
BLOCK_SOFTIRQ,
TASKLET_SOFTIRQ,
SCHED_SOFTIRQ,
HRTIMER_SOFTIRQ,
RCU_SOFTIRQ, /* Preferable RCU should always be the last softirq */
NR_SOFTIRQS
};
static void tasklet_action(struct softirq_action *a)
{
struct tasklet_struct *list;
local_irq_disable();
list = __get_cpu_var(tasklet_vec).head;////////kernel/softirq.c:static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec);
__get_cpu_var(tasklet_vec).head = NULL;
__get_cpu_var(tasklet_vec).tail = &__get_cpu_var(tasklet_vec).head;
local_irq_enable();
while (list) {
struct tasklet_struct *t = list;
list = list->next;
if (tasklet_trylock(t)) {
if (!atomic_read(&t->count)) {
if (!test_and_clear_bit(TASKLET_STATE_SCHED, &t->state))
BUG();
t->func(t->data);
tasklet_unlock(t);
continue;
}
tasklet_unlock(t);
}
local_irq_disable();
t->next = NULL;
*__get_cpu_var(tasklet_vec).tail = t;
__get_cpu_var(tasklet_vec).tail = &(t->next);
__raise_softirq_irqoff(TASKLET_SOFTIRQ);
local_irq_enable();
}
}
void tasklet_init(struct tasklet_struct *t,
void (*func)(unsigned long), unsigned long data)
{
t->next = NULL;
t->state = 0;
atomic_set(&t->count, 0);
t->func = func;
t->data = data;
}
/include/linux/interrupt.h
static inline void tasklet_disable(struct tasklet_struct *t)
{
tasklet_disable_nosync(t);
tasklet_unlock_wait(t);
smp_mb();
}
static inline void tasklet_enable(struct tasklet_struct *t)
{
smp_mb__before_atomic_dec();
atomic_dec(&t->count);
}
static inline void tasklet_schedule(struct tasklet_struct *t)
{
if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state))
__tasklet_schedule(t); //此功能就是将本tasklet_struct 添加到那个链表上去，然后判断是否在中断中，如果不是，唤醒ksoftirqd,准备执行软中断，还有就是每次硬件中断执行完，可能调用软中断
}