展锐USB 插拔更新充电状态分析
介绍
在charger-manager.c 中有注册usb 状态改变的通知，当我们插拔USB时会触发policy_usb_change_callback() 方法
bsp/kernel/kernel4.14/drivers/power/supply/charger-manager.c
static int charger_manager_policy_init(struct charger_manager *cm)
{
...
cm->policy.usb_notify.notifier_call = policy_usb_change_callback;
ret = usb_register_notifier(cm->policy.usb_phy, &cm->policy.usb_notify);
...
}在调查USB充电流程时，发现给FW层上报充电状态时，是通过这个回调方法通知FW充电状态发生了变化，然后SystemUI 的Status Bar可以及时更新充电图标。通过这篇文章记录下插拔USB时调用到此回调的一个流程。
USB 插拔中断事件
在我当前的展锐平台上，加载了extcon-usb-gpio 驱动，这个驱动可以检测USB 的插拔动作，当我们插入USB 会触发系统GPIO中断
1. 加载extcon-usb-gpio 驱动
bsp/kernel/kernel4.14/drivers/extcon/Makefile
...
# 开机默认加载此驱动
obj-$(CONFIG_EXTCON_USB_GPIO) += extcon-usb-gpio.o
...2. extcon-usb-gpio驱动初始化
bsp/kernel/kernel4.14/drivers/extcon/extcon-usb-gpio.c
static const struct of_device_id usb_extcon_dt_match[] = {
{ .compatible = "linux,extcon-usb-gpio", },
{ /* sentinel */ }
};
static struct platform_driver usb_extcon_driver = {
.probe = usb_extcon_probe, // probe 函数，驱动匹配到了对应的设备后会调用此函数
.remove = usb_extcon_remove, // 设备移除后会调用此函数
.driver = {
.name = "extcon-usb-gpio", // 该驱动的name
.pm = &usb_extcon_pm_ops, // 电源相关
.of_match_table = usb_extcon_dt_match, // 用于匹配dts文件里的设备，如果有compatible 相同的设备后才会调用probe 函数
},
.id_table = usb_extcon_platform_ids,
};
module_platform_driver(usb_extcon_driver); // 该驱动的入口函数首先会在dts 文件中匹配compatible为linux,extcon-usb-gpio的文件，需要分析硬件设计图，查看USB插拔的中断口，如下
&extcon_gpio {
compatible = "linux,extcon-usb-gpio";
vbus-gpio = <&pmic_eic 0 GPIO_ACTIVE_HIGH>;
id-gpio = <&eic_debounce 4 GPIO_ACTIVE_HIGH>;
};probe 函数为驱动的初始化函数，当我们加载此驱动后，会在bus 总线上寻找对应的device，如果有匹配的device，则系统会默认调用此驱动的probe 函数，在如下目录可以发现我们的设备已经成功加载了此驱动
sys/bus/platform/drivers/extcon-usb-gpio
接着查看probe 函数,这里面会获取dts中配置的gpio 口，然后设置中断
bsp/kernel/kernel4.14/drivers/extcon/extcon-usb-gpio.c
static int usb_extcon_probe(struct platform_device *pdev)
{
...
info->id_gpiod = devm_gpiod_get_optional(&pdev->dev, "id", GPIOD_IN);
info->vbus_gpiod = devm_gpiod_get_optional(&pdev->dev, "vbus", GPIOD_IN);
...
if (info->id_gpiod)
// 用于防抖的
ret = gpiod_set_debounce(info->id_gpiod, USB_GPIO_DEBOUNCE_MS * 1000);
if (!ret && info->vbus_gpiod)
ret = gpiod_set_debounce(info->vbus_gpiod, USB_GPIO_DEBOUNCE_MS * 1000);
...
if (info->id_gpiod) {
info->id_irq = gpiod_to_irq(info->id_gpiod); // 将id-gpio 口设置为中断模式
...
// 设置中断条件，发生中断是调用usb_irq_handler() 方法，当GPIO 上拉或者下拉时触发中断
ret = devm_request_threaded_irq(dev, info->id_irq, NULL,
usb_irq_handler,
IRQF_TRIGGER_RISING |
IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
pdev->name, info);
...
}
if (info->vbus_gpiod) {
info->vbus_irq = gpiod_to_irq(info->vbus_gpiod); // 将vbus-gpio 口设置为中断模式
...
// 设置中断条件，发生中断是调用usb_irq_handler() 方法，当GPIO 上拉或者下拉时触发中断
ret = devm_request_threaded_irq(dev, info->vbus_irq, NULL,
usb_irq_handler,
IRQF_TRIGGER_RISING |
IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
pdev->name, info);
...
}
...
}3. 中断回调函数
当id-gpio 和 vbus-gpio 口上拉或者下拉时触发中断，调用usb_irq_handler() 中断，上拉或者下拉代表USB 的插入和拔出。
bsp/kernel/kernel4.14/drivers/extcon/extcon-usb-gpio.c
static irqreturn_t usb_irq_handler(int irq, void *dev_id)
{
struct usb_extcon_info *info = dev_id;
queue_delayed_work(system_power_efficient_wq, &info->wq_detcable,
info->debounce_jiffies);
return IRQ_HANDLED;
}
static int usb_extcon_probe(struct platform_device *pdev)
{
...
// 初始化工作队列wq_detcable 为usb_extcon_detect_cable() 方法
INIT_DELAYED_WORK(&info->wq_detcable, usb_extcon_detect_cable);
...
}
static void usb_extcon_detect_cable(struct work_struct *work)
{
int id, vbus;
struct usb_extcon_info *info = container_of(to_delayed_work(work),
struct usb_extcon_info,
wq_detcable);
// 读取id 和vbus gpio口，用于判断当前是上拉中断还是下拉产生的中断
id = info->id_gpiod ?
gpiod_get_value_cansleep(info->id_gpiod) : 1;
vbus = info->vbus_gpiod ?
gpiod_get_value_cansleep(info->vbus_gpiod) : id;
// 拔出USB 触发的中断
if (id)
extcon_set_state_sync(info->edev, EXTCON_USB_HOST, false);
if (!vbus)
extcon_set_state_sync(info->edev, EXTCON_USB, false);
// 插入USB 触发的中断
if (!id) {
extcon_set_state_sync(info->edev, EXTCON_USB_HOST, true);
} else {
if (vbus)
extcon_set_state_sync(info->edev, EXTCON_USB, true);
}
}在USB插拔触发中断时，会调用info->wq_detcable 工，即作队列会调用usb_extcon_detect_cable() 方法，之后会通过extcon_set_state_sync() 方法设置USB 的状态。
bsp/kernel/kernel4.14/drivers/extcon/extcon.c
int extcon_set_state_sync(struct extcon_dev *edev, unsigned int id, bool state)
{
int ret, index;
unsigned long flags;
index = find_cable_index_by_id(edev, id);
if (index < 0)
return index;
/* Check whether the external connector's state is changed. */
spin_lock_irqsave(&edev->lock, flags);
ret = is_extcon_changed(edev, index, state); // 检查USB状态是否发生了变化
spin_unlock_irqrestore(&edev->lock, flags);
if (!ret)
return 0;
ret = extcon_set_state(edev, id, state); // 设置USB 的连接状态，但是不会通知USB 状态的改变
if (ret < 0)
return ret;
return extcon_sync(edev, id); // 设置USB 的连接状态并通知其他模块
}
EXPORT_SYMBOL_GPL(extcon_set_state_sync);
int extcon_sync(struct extcon_dev *edev, unsigned int id)
{
...
// 通过这个方法通知某个注册了USB 状态改变的模块
raw_notifier_call_chain(&edev->nh[index], state, edev);
// 通过这个方法通知所有注册了USB 状态改变的模块
raw_notifier_call_chain(&edev->nh_all, state, edev);
...
kobject_uevent_env(&edev->dev.kobj, KOBJ_CHANGE, envp); // 通过UEvent 通知用户空间USB发生了改变
free_page((unsigned long)prop_buf);
return 0;
}
EXPORT_SYMBOL_GPL(extcon_sync);bsp/kernel/kernel4.14/kernel/notifier.c
int raw_notifier_call_chain(struct raw_notifier_head *nh,
unsigned long val, void *v)
{
return __raw_notifier_call_chain(nh, val, v, -1, NULL);
}
EXPORT_SYMBOL_GPL(raw_notifier_call_chain);
int __raw_notifier_call_chain(struct raw_notifier_head *nh,
unsigned long val, void *v,
int nr_to_call, int *nr_calls)
{
return notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls);
}
EXPORT_SYMBOL_GPL(__raw_notifier_call_chain);
static int notifier_call_chain(struct notifier_block **nl,
unsigned long val, void *v,
int nr_to_call, int *nr_calls)
{
int ret = NOTIFY_DONE;
struct notifier_block *nb, *next_nb;
nb = rcu_dereference_raw(*nl);
// 循环读取所有的notifier_block, 然后调用它的notifier_call() 方法
while (nb && nr_to_call) {
next_nb = rcu_dereference_raw(nb->next);
...
ret = nb->notifier_call(nb, val, v);
if (nr_calls)
(*nr_calls)++;
if (ret & NOTIFY_STOP_MASK)
break;
nb = next_nb;
nr_to_call--;
}
return ret;
}
NOKPROBE_SYMBOL(notifier_call_chain);从log分析可以看到，nb->notifier_call() 方法会调用sprd_hsphy_vbus_notify() 方法
[14:53:40:749] [ 51.173699] c2 [
] (unwind_backtrace) from [ ] (show_stack+0x20/0x24)␍␊ [14:53:40:757] [ 51.181677] c2 [
] (show_stack) from [ ] (dump_stack+0xa4/0xd8)␍␊ [14:53:40:761] [ 51.189129] c2 [
] (dump_stack) from [ ] (sprd_hsphy_vbus_notify+0x48/0x30c)␍␊ [14:53:40:774] [ 51.197722] c2 [
] (sprd_hsphy_vbus_notify) from [ ] (notifier_call_chain+0x74/0xac)␍␊ [14:53:40:779] [ 51.207006] c2 [
] (notifier_call_chain) from [ ] (raw_notifier_call_chain+0x28/0x30)␍␊ [14:53:40:792] [ 51.216371] c2 [
] (raw_notifier_call_chain) from [ ] (extcon_sync+0x78/0x1e4)␍␊ [14:53:40:801] [ 51.225137] c2 [
] (extcon_sync) from [ ] (extcon_set_state_sync+0x7c/0x90)␍␊ [14:53:40:806] [ 51.233639] c2 [
] (extcon_set_state_sync) from [ ] (usb_extcon_detect_cable+0xa8/0xac)␍␊ [14:53:40:815] [ 51.243185] c2 [
] (usb_extcon_detect_cable) from [ ] (process_one_work+0x290/0x4a8)␍␊ [14:53:40:825] [ 51.252466] c2 [
] (process_one_work) from [ ] (worker_thread+0x2f8/0x478)␍␊ [14:53:40:833] [ 51.260887] c2 [
] (worker_thread) from [ ] (kthread+0x148/0x164)␍␊ [14:53:40:844] [ 51.268519] c2 [
] (kthread) from [ ] (ret_from_fork+0x14/0x20)
接着查看sprd_hsphy_vbus_notify() 方法的流程
bsp/kernel/kernel4.14/drivers/usb/phy/phy-sprd-sharkle.c
static int sprd_hsphy_vbus_notify(struct notifier_block *nb,
unsigned long event, void *data)
{
struct usb_phy *usb_phy = container_of(nb, struct usb_phy, vbus_nb);
struct sprd_hsphy *phy = container_of(usb_phy, struct sprd_hsphy, phy);
...
// event 的值是我们传入的USB 状态(state),state = 1 表示USB 插入，否则没有插入
if (event) {
/* usb vbus valid */
reg = readl_relaxed(phy->base + REG_AP_AHB_OTG_PHY_TEST);
reg |= (MASK_AP_AHB_OTG_VBUS_VALID_EXT |
MASK_AP_AHB_OTG_VBUS_VALID_PHYREG);
writel_relaxed(reg, phy->base + REG_AP_AHB_OTG_PHY_TEST);
usb_phy_set_charger_state(usb_phy, USB_CHARGER_PRESENT);
} else {
/* usb vbus invalid */
reg = readl_relaxed(phy->base + REG_AP_AHB_OTG_PHY_TEST);
reg &= ~(MASK_AP_AHB_OTG_VBUS_VALID_PHYREG |
MASK_AP_AHB_OTG_VBUS_VALID_EXT);
writel_relaxed(reg, phy->base + REG_AP_AHB_OTG_PHY_TEST);
usb_phy_set_charger_state(usb_phy, USB_CHARGER_ABSENT);
}
return 0;
}bsp/kernel/kernel4.14/drivers/usb/phy/phy.c
void usb_phy_set_charger_state(struct usb_phy *usb_phy,
enum usb_charger_state state)
{
...
usb_phy->chg_state = state;
if (usb_phy->chg_state != USB_CHARGER_PRESENT)
usb_phy->chg_type = UNKNOWN_TYPE;
schedule_work(&usb_phy->chg_work);
}
EXPORT_SYMBOL_GPL(usb_phy_set_charger_state);
static void usb_charger_init(struct usb_phy *usb_phy)
{
usb_phy->chg_type = UNKNOWN_TYPE;
usb_phy->chg_state = USB_CHARGER_DEFAULT;
usb_phy_set_default_current(usb_phy);
INIT_WORK(&usb_phy->chg_work, usb_phy_notify_charger_work); // 初始化usb_phy->chg_work 工作队列
}调用usb_phy_set_charger_state() 方法后，会调用usb_phy_notify_charger_work() 方法
bsp/kernel/kernel4.14/drivers/usb/phy/phy.c
static void usb_phy_notify_charger_work(struct work_struct *work)
{
...
// 判断USB的插入状态，如果是插入状态，则走USB_CHARGER_PRESENT 分支
switch (usb_phy->chg_state) {
case USB_CHARGER_PRESENT:
if (usb_phy->chg_type == UNKNOWN_TYPE)
usb_phy->chg_type = usb_phy->charger_detect(usb_phy);
usb_phy_get_charger_current(usb_phy, &min, &max);
atomic_notifier_call_chain(&usb_phy->notifier, max, usb_phy); //调用usb_phy中注册的回调方法
snprintf(uchger_state, ARRAY_SIZE(uchger_state),
"USB_CHARGER_STATE=%s", "USB_CHARGER_PRESENT");
break;
case USB_CHARGER_ABSENT:
usb_phy_set_default_current(usb_phy);
atomic_notifier_call_chain(&usb_phy->notifier, 0, usb_phy); //调用usb_phy中注册的回调方法
snprintf(uchger_state, ARRAY_SIZE(uchger_state),
"USB_CHARGER_STATE=%s", "USB_CHARGER_ABSENT");
break;
default:
...
// 使用ueven 通知方法通知用户
kobject_uevent_env(&usb_phy->dev->kobj, KOBJ_CHANGE, envp);
}atomic_notifier_call_chain() 方法定义在notifier.c 中
bsp/kernel/kernel4.14/kernel/notifier.c
int atomic_notifier_call_chain(struct atomic_notifier_head *nh,
unsigned long val, void *v)
{
return __atomic_notifier_call_chain(nh, val, v, -1, NULL);
}
int __atomic_notifier_call_chain(struct atomic_notifier_head *nh,
unsigned long val, void *v,
int nr_to_call, int *nr_calls)
{
...
ret = notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls);
...
return ret;
}
static int notifier_call_chain(struct notifier_block **nl,
unsigned long val, void *v,
int nr_to_call, int *nr_calls)
{
...
nb = rcu_dereference_raw(*nl); // 这个nb 是usb_phy 通知块的头部块
// 回调所有注册的notifier_call 函数
while (nb && nr_to_call) {
next_nb = rcu_dereference_raw(nb->next);
...
ret = nb->notifier_call(nb, val, v);
if (nr_calls)
(*nr_calls)++;
if (ret & NOTIFY_STOP_MASK)
break;
nb = next_nb;
nr_to_call--;
}
return ret;
}从usb_phy_notify_charger_work() 方法传入的nh是usb_phy。
以charger-manager 为例，在charger-manager.c 的charger_manager_policy_init() 方法中注册了usb_phy.notifier_call 方法
4. charger-manager 注册USB 状态改变通知
bsp/kernel/kernel4.14/drivers/power/supply/charger-manager.c
static int charger_manager_policy_init(struct charger_manager *cm)
{
...
cm->policy.usb_notify.notifier_call = policy_usb_change_callback;
ret = usb_register_notifier(cm->policy.usb_phy, &cm->policy.usb_notify);
...
}通过usb_register_notifier() 方法注册回调方法
bsp/kernel/kernel4.14/include/linux/usb/phy.h
static inline int
usb_register_notifier(struct usb_phy *x, struct notifier_block *nb)
{
return atomic_notifier_chain_register(&x->notifier, nb);
}将回调添加到usb_phy 通知块的头部，如果USB 发生了中断，则会调用到这个回调
bsp/kernel/kernel4.14/kernel/notifier.c
int atomic_notifier_chain_register(struct atomic_notifier_head *nh,
struct notifier_block *n)
{
...
ret = notifier_chain_register(&nh->head, n);
...
}
// 将usb_notify 通知块添加到usb_phy 里通知块的头部
static int notifier_chain_register(struct notifier_block **nl,
struct notifier_block *n)
{
while ((*nl) != NULL) {
if (n->priority > (*nl)->priority)
break;
nl = &((*nl)->next);
}
n->next = *nl;
rcu_assign_pointer(*nl, n);
return 0;
}所以在我们插入USB时，会调用到charger-manager.c::policy_usb_change_callback() 方法