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这就是实现三个状态转换的三个钩子函数.
这个函数较为简单, 只是将/kerenel/power/main.c里的全局变量suspend_ops设置成
s3c_pm_ops而已了.
这就完成了这个全局变量的初始化.后续对suspend_ops的访问实质上都是访问s3c_pm_ops.
void suspend_set_ops(struct platform_suspend_ops *ops)
{
mutex_lock(&pm_mutex);
suspend_ops = ops;
mutex_unlock(&pm_mutex);
}
最后看看函数实现：
static int s3c_pm_prepare(void)
{
/* prepare check area if configured */
s3c_pm_check_prepare();
return 0;
}
static void s3c_pm_finish(void)
{
s3c_pm_check_cleanup();
}
这里主要是s3c_pm_nter函数：
static int s3c_pm_enter(suspend_state_t state)
{
//用于保存16个通用寄存器的栈
static unsigned long regs_save[16];
/* ensure the debug is initialised (if enabled) */
s3c_pm_debug_init();
S3C_PMDBG(“%s(%d)\n”, __func__, state);
if (pm_cpu_prep == NULL || pm_cpu_sleep == NULL) {
printk(KERN_ERR “%s: error: no cpu sleep function\n”, __func__);
return -EINVAL;
}
/* check if we have anything to wake-up with… bad things seem
* to happen if you suspend with no wakeup (system will often
* require a full power-cycle)
*/
//检查允许的唤醒中断
if (!any_allowed(s3c_irqwake_intmask, s3c_irqwake_intallow) &&
!any_allowed(s3c_irqwake_eintmask, s3c_irqwake_eintallow)) {
printk(KERN_ERR “%s: No wake-up sources!\n”, __func__);
printk(KERN_ERR “%s: Aborting sleep\n”, __func__);
return -EINVAL;
}
/* store the physical address of the register recovery block */
//寄存器的物理地址
s3c_sleep_save_phys = virt_to_phys(regs_save);
S3C_PMDBG(“s3c_sleep_save_phys=0x%08lx\n”, s3c_sleep_save_phys);
//保存不属于driver的核心寄存器, driver的各自保存
s3c_pm_save_gpios();
s3c_pm_save_uarts();
s3c_pm_save_core();
/* set the irq configuration for wake */
//设置外部中断用于唤醒
s3c_pm_configure_extint();
S3C_PMDBG(“sleep: irq wakeup masks: %08lx,%08lx\n”,
s3c_irqwake_intmask, s3c_irqwake_eintmask);
s3c_pm_arch_prepare_irqs();
/* call cpu specific preparation */
pm_cpu_prep();
/* flush cache back to ram */
flush_cache_all();
s3c_pm_check_store();
/* send the cpu to sleep… */
s3c_pm_arch_stop_clocks();
/* s3c_cpu_save will also act as our return point from when
* we resume as it saves its own register state and restores it
* during the resume. */
s3c_cpu_save(regs_save);
/* restore the cpu state using the kernel’s cpu init code. */
//当接收到一个外部中断时,系统开始恢复
cpu_init();
/* restore the system state */
s3c_pm_restore_core();
s3c_pm_restore_uarts();
s3c_pm_restore_gpios();
s3c_pm_debug_init();
/* check what irq (if any) restored the system */
s3c_pm_arch_show_resume_irqs();
S3C_PMDBG(“%s: post sleep, preparing to return\n”, __func__);
s3c_pm_check_restore();
/* ok, let’s return from sleep */
S3C_PMDBG(“S3C PM Resume (post-restore)\n”);
return 0;
}
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别人失去了信心，他却下决心实现自己的目标。
