MSM8X60 USB控制器流程分析,其中去掉了沒有用到的代碼,以便把握整個主線不被幹擾。
static int msm_otg_set_peripheral(struct otg_transceiver *xceiv,
struct usb_gadget *gadget)
{
struct msm_otg *dev = container_of(xceiv, struct msm_otg, otg);
............
dev->otg.gadget = gadget;
pr_info("peripheral driver registered w/ tranceiver\n");
wake_lock(&dev->wlock);//鎖定wakelock,防止睡眠
queue_work(dev->wq, &dev->sm_work);//排程work
return 0;
}
static irqreturn_t msm_otg_irq(int irq, void *data)
{
struct msm_otg *dev = data;
u32 otgsc, sts, pc, sts_mask;
int work = 0;
enum usb_otg_state state;
if (atomic_read(&dev->in_lpm)) {//插入usb時,如果處于睡眠,則喚醒
disable_irq_nosync(dev->irq);
wake_lock(&dev->wlock);//鎖定wakelock
queue_work(dev->wq, &dev->otg_resume_work);//進入喚醒流程
goto out;
}
otgsc = readl(USB_OTGSC);
sts = readl(USB_USBSTS);
sts_mask = (otgsc & OTGSC_INTR_MASK) >> 8;//該寄存器的中斷使能掩碼
if (!((otgsc & sts_mask) || (sts & STS_PCI))) {//如果沒有變化,則迅速退出,因為該中斷為共享中斷
ret = IRQ_NONE;
goto out;
}
state = dev->otg.state;//取出上次的狀态
if ((otgsc & OTGSC_IDIE) && (otgsc & OTGSC_IDIS)) {//檢測到id引腳有變換
if (otgsc & OTGSC_ID) {//id引腳值為1,則設定id位,為client
pr_debug("Id set\n");
set_bit(ID, &dev->inputs);
} else {//id引腳值為0,則清除id位,host
pr_debug("Id clear\n");
set_bit(A_BUS_REQ, &dev->inputs);
clear_bit(ID, &dev->inputs);
}
writel(otgsc, USB_OTGSC);//清除該寄存器,以便下次接收中斷
work = 1;
} else if (otgsc & OTGSC_BSVIS) {//檢測到VBUS有變換
writel(otgsc, USB_OTGSC);//清除該寄存器,以便下次接收中斷
if ((state >= OTG_STATE_A_IDLE) &&
!test_bit(ID_A, &dev->inputs))
goto out;
if (otgsc & OTGSC_BSV) {//表示usb cable插入
pr_debug("BSV set\n");
set_bit(B_SESS_VLD, &dev->inputs);
} else {//表示usb cable移除
pr_debug("BSV clear\n");
clear_bit(B_SESS_VLD, &dev->inputs);
}
work = 1;
} else if (sts & STS_PCI) {//表示端口變化中斷
pc = readl(USB_PORTSC);
pr_debug("portsc = %x\n", pc);
ret = IRQ_NONE;
work = 1;
switch (state) {
..............
default:
PR_DEBUG_ON
work = 0;
break;
}
}
if (work) {//work為1,則排程work,并鎖定wakelock
wake_lock(&dev->wlock);
queue_work(dev->wq, &dev->sm_work);
}
out:
return ret;
}
排程的work如下:
static void msm_otg_sm_work(struct work_struct *w)
{
struct msm_otg *dev = container_of(w, struct msm_otg, sm_work);
int work = 0;
enum usb_otg_state state;
if (atomic_read(&dev->in_lpm))//進入runtime喚醒流程
msm_otg_set_suspend(&dev->otg, 0);
state = dev->otg.state;//第一次狀态沒有初始化,預設為0
switch (state) {
case OTG_STATE_UNDEFINED:
otg_reset(&dev->otg, 1);//第一次所走路線
if (!dev->otg.host || !is_host())//第一次所走路線
set_bit(ID, &dev->inputs);
if (dev->otg.gadget && is_b_sess_vld())
set_bit(B_SESS_VLD, &dev->inputs);
if ((test_bit(ID, &dev->inputs)) &&
!test_bit(ID_A, &dev->inputs)) {
dev->otg.state = OTG_STATE_B_IDLE;//第一次所走路線
} else {
set_bit(A_BUS_REQ, &dev->inputs);
dev->otg.state = OTG_STATE_A_IDLE;
}
work = 1;//排程work
break;
case OTG_STATE_B_IDLE:
dev->otg.default_a = 0;
if (test_bit(B_SESS_VLD, &dev->inputs) &&
!test_bit(ID_B, &dev->inputs)) {//第二次所走路線
pr_debug("b_sess_vld\n");
spin_lock_irqsave(&dev->lock, flags);
dev->otg.state = OTG_STATE_B_PERIPHERAL;
spin_unlock_irqrestore(&dev->lock, flags);
msm_otg_set_power(&dev->otg, 0);
msm_otg_start_peripheral(&dev->otg, 1);
} else {
msm_otg_set_power(&dev->otg, 0);第一次所走路線
pr_debug("entering into lpm\n");
msm_otg_put_suspend(dev);//進入runtime睡眠流程
if (dev->pdata->ldo_set_voltage)
dev->pdata->ldo_set_voltage(3075);
}
break;
case OTG_STATE_B_PERIPHERAL:
if (!test_bit(ID, &dev->inputs) ||
test_bit(ID_A, &dev->inputs) ||
test_bit(ID_B, &dev->inputs) ||
!test_bit(B_SESS_VLD, &dev->inputs)) {
pr_debug("!id || id_a/b || !b_sess_vld\n");
clear_bit(B_BUS_REQ, &dev->inputs);
spin_lock_irqsave(&dev->lock, flags);
dev->otg.state = OTG_STATE_B_IDLE;
spin_unlock_irqrestore(&dev->lock, flags);
msm_otg_start_peripheral(&dev->otg, 0);
dev->b_last_se0_sess = jiffies;
otg_reset(&dev->otg, 1);
work = 1;
}
break;
default:
pr_err("invalid OTG state\n");
}
if (work)
queue_work(dev->wq, &dev->sm_work);//第一次所走路線
if (!work_pending(&dev->sm_work) && !hrtimer_active(&dev->timer) &&
!work_pending(&dev->otg_resume_work))
wake_unlock(&dev->wlock);//所用的work,timer的處理函數都執行完時,解鎖wakelock
}
1、沒有插入usb時,系統初始化第一次排程work後dev->otg.state為OTG_STATE_B_IDLE,再次排程work,進入low power模式,解鎖wakelock,睡眠。
2、插入usb時,系統從OTG_STATE_B_IDLE醒來,在otg irq中喚醒系統,并鎖定wakelock,然後繼續處理硬體中斷,開啟外圍裝置控制器。并設定dev->otg.state的狀态為OTG_STATE_B_PERIPHERAL;
3、當usb移除的時候,排程work,再次設定dev->otg.state為OTG_STATE_B_IDLE,并關閉裝置控制器。繼續排程work,進入low power模式,并解鎖wakelock,進入系統睡眠。
http://blog.chinaunix.net/uid-25909619-id-3323921.html