Android OrangePi 4G IOT(五) - MTK电源管理驱动（一）

一、MTK电源管理组成

这里讲的电源管理驱动主要是SPM驱动，CPU idle驱动，CPU Hotplug驱动，CPU Frequency驱动等，代码主要集中在以下目录。

1：/home/ubuntu/Mediatek/code/kernel-3.18/drivers/misc/mediatek/base/power/

2：/home/ubuntu/Mediatek/code/kernel-3.18/drivers/base/power

3：/home/ubuntu/Mediatek/code/kernel-3.18/kernel/power/

4：/home/ubuntu/Mediatek/code/kernel-3.18/drivers/cpufreq/

5：/home/ubuntu/Mediatek/code/kernel-3.18/drivers/cpuidle/

二、Linux kernel Generic Power

1：Linux power初始化，首先使用pm_init初始化power manager工作队列，设置休眠镜像大小，创建attribute属性等。

/home/ubuntu/Mediatek/code/kernel-3.18/kernel/power/main.c

static struct attribute * g[] = {&state_attr.attr,
#ifdef CONFIG_PM_TRACE&pm_trace_attr.attr,&pm_trace_dev_match_attr.attr,
#endif
#ifdef CONFIG_PM_SLEEP&pm_async_attr.attr,&wakeup_count_attr.attr,
#ifdef CONFIG_PM_AUTOSLEEP&autosleep_attr.attr,
#endif
#ifdef CONFIG_PM_WAKELOCKS&wake_lock_attr.attr,&wake_unlock_attr.attr,
#endif
#ifdef CONFIG_PM_DEBUG&pm_test_attr.attr,
#endif
#ifdef CONFIG_PM_SLEEP_DEBUG&pm_print_times_attr.attr,
#endif
#endif
#ifdef CONFIG_FREEZER&pm_freeze_timeout_attr.attr,
#endif
//CodeSwitching start
#if 1// HIGUA&custom_changelogo_attr.attr,
#endif
//CodeSwitching endNULL,
};static struct attribute_group attr_group = {.attrs = g,
};struct workqueue_struct *pm_wq;
EXPORT_SYMBOL_GPL(pm_wq);static int __init pm_start_workqueue(void)
{pm_wq = alloc_workqueue("pm", WQ_FREEZABLE, 0);return pm_wq ? 0 : -ENOMEM;
}static int __init pm_init(void)
{int error = pm_start_workqueue();if (error)return error;hibernate_image_size_init();hibernate_reserved_size_init();power_kobj = kobject_create_and_add("power", NULL);if (!power_kobj)return -ENOMEM;error = sysfs_create_group(power_kobj, &attr_group);if (error)return error;pm_print_times_init();return pm_autosleep_init();
}core_initcall(pm_init);

2：Android用户层通过按键按钮触发 ‘echo mem > /sys/power/state’进行休眠相关的一些列流程

用户层这个命令是通过上述命令进行触发，处理代码为

/home/ubuntu/Mediatek/code/kernel-3.18/kernel/power/main.c

static ssize_t state_store(struct kobject *kobj, struct kobj_attribute *attr,const char *buf, size_t n)
{suspend_state_t state;int error;#ifdef CONFIG_MTK_HIBERNATIONchar *p;int len;
#endiferror = pm_autosleep_lock();if (error)return error;if (pm_autosleep_state() > PM_SUSPEND_ON) {error = -EBUSY;goto out;}state = decode_state(buf, n);#ifdef CONFIG_MTK_HIBERNATIONp = memchr(buf, '\n', n);len = p ? p - buf : n;if (len == 8 && !strncmp(buf, "hibabort", len)) {hib_log("abort hibernation...\n");error = mtk_hibernate_abort();goto out;}
#endifpr_warn("[%s]: state = (%d)\n", __func__, state);if (state < PM_SUSPEND_MAX) {error = pm_suspend(state);pr_warn("[%s]: pm_suspend() return (%d)\n", __func__, error);} else if (state == PM_SUSPEND_MAX) {
#ifdef CONFIG_MTK_HIBERNATIONhib_log("trigger hibernation...\n");if (!pre_hibernate()) {error = 0;error = mtk_hibernate();}
#else /* !CONFIG_MTK_HIBERNATION */error = hibernate();
#endif /* CONFIG_MTK_HIBERNATION */} else {error = -EINVAL;}out:pm_autosleep_unlock();return error ? error : n;
}power_attr(state);

3：进入pm_suspend流程，进入enter_state处理，然后进行相关的suspend_syssync_enqueue，suspend_prepare，suspend_devices_and_enter。

代码如下

/*** pm_suspend - Externally visible function for suspending the system.* @state: System sleep state to enter.** Check if the value of @state represents one of the supported states,* execute enter_state() and update system suspend statistics.*/
int pm_suspend(suspend_state_t state)
{int error;if (state <= PM_SUSPEND_ON || state >= PM_SUSPEND_MAX)return -EINVAL;pm_suspend_marker("entry");error = enter_state(state);if (error) {suspend_stats.fail++;dpm_save_failed_errno(error);} else {suspend_stats.success++;}pm_suspend_marker("exit");return error;
}
EXPORT_SYMBOL(pm_suspend);

/*** enter_state - Do common work needed to enter system sleep state.* @state: System sleep state to enter.** Make sure that no one else is trying to put the system into a sleep state.* Fail if that's not the case.  Otherwise, prepare for system suspend, make the* system enter the given sleep state and clean up after wakeup.*/
static int enter_state(suspend_state_t state)
{int error;trace_suspend_resume(TPS("suspend_enter"), state, true);if (state == PM_SUSPEND_FREEZE) {
#ifdef CONFIG_PM_DEBUGif (pm_test_level != TEST_NONE && pm_test_level <= TEST_CPUS) {pr_warning("PM: Unsupported test mode for freeze state,""please choose none/freezer/devices/platform.\n");return -EAGAIN;}
#endif} else if (!valid_state(state)) {return -EINVAL;}if (!mutex_trylock(&pm_mutex))return -EBUSY;if (state == PM_SUSPEND_FREEZE)freeze_begin();trace_suspend_resume(TPS("sync_filesystems"), 0, true);printk(KERN_INFO "PM: Syncing filesystems ... ");
#if MTK_SOLUTIONerror = suspend_syssync_enqueue();if (error) {pr_err("sys_sync timeout.\n");goto Unlock;}
#elsesys_sync();
#endifprintk("done.\n");trace_suspend_resume(TPS("sync_filesystems"), 0, false);pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);error = suspend_prepare(state);if (error)goto Unlock;if (suspend_test(TEST_FREEZER))goto Finish;trace_suspend_resume(TPS("suspend_enter"), state, false);pr_debug("PM: Entering %s sleep\n", pm_states[state]);pm_restrict_gfp_mask();error = suspend_devices_and_enter(state);pm_restore_gfp_mask();Finish:pr_debug("PM: Finishing wakeup.\n");suspend_finish();Unlock:mutex_unlock(&pm_mutex);return error;
}

三、suspend和resume流程

流程图如下所示:

在suspend中最终进入到syscore_suspend中最后调用到ops->suspend，反之在suspend流程在代码中同样suspend后执行逆向的过程

 syscore_resume();}arch_suspend_enable_irqs();BUG_ON(irqs_disabled());Enable_cpus:enable_nonboot_cpus();Platform_wake:platform_resume_noirq(state);dpm_resume_noirq(PMSG_RESUME);Platform_early_resume:platform_resume_early(state);Devices_early_resume:dpm_resume_early(PMSG_RESUME);Platform_finish:platform_resume_finish(state);