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android emulator虚拟设备之qemu pipe分析(三),Android高级工程师进阶学习】

2022-01-29 12:59:38  阅读:76  来源: 互联网

标签:__ PIPE 进阶 dev pipe emulator address channel


while (address < address_end) {

unsigned long  page_end = (address & PAGE_MASK) + PAGE_SIZE;

unsigned long  next     = page_end < address_end ? page_end
address_end;

unsigned long  avail    = next - address;

int status, wakeBit;

/* Ensure that the corresponding page is properly mapped */

if (is_write) {

char c;

/* Ensure that the page is mapped and readable */

if (__get_user(c, (char __user *)address)) {

PIPE_E(“read fault at address 0x%08x\n”,

(unsigned int)address);

if (!ret)

ret = -EFAULT;

break;

}

} else {

/* Ensure that the page is mapped and writable */

if (__put_user(0, (char __user *)address)) {

PIPE_E(“write fault at address 0x%08x\n”,

(unsigned int)address);

if (!ret)

ret = -EFAULT;

break;

}

}

/* Now, try to transfer the bytes in the current page */

spin_lock_irqsave(&dev->lock, irq_flags);

if (dev->aps == NULL || access_with_param(

dev, CMD_WRITE_BUFFER + cmd_offset, address, avail,

pipe, &status) < 0)

{

writel((unsigned long)pipe,

dev->base + PIPE_REG_CHANNEL);

writel(avail, dev->base + PIPE_REG_SIZE);

writel(address, dev->base + PIPE_REG_ADDRESS);

writel(CMD_WRITE_BUFFER + cmd_offset,

dev->base + PIPE_REG_COMMAND);

status = readl(dev->base + PIPE_REG_STATUS);

}

spin_unlock_irqrestore(&dev->lock, irq_flags);

if (status > 0) { /* Correct transfer */

ret += status;

address += status;

continue;

}

if (status == 0)  /* EOF */

break;

/* An error occured. If we already transfered stuff, just

* return with its count. We expect the next call to return

* an error code */

if (ret > 0)

break;

/* If the error is not PIPE_ERROR_AGAIN, or if we are not in

* non-blocking mode, just return the error code.

*/

if (status != PIPE_ERROR_AGAIN ||

(filp->f_flags & O_NONBLOCK) != 0) {

ret = qemu_pipe_error_convert(status);

break;

}

/* We will have to wait until more data/space is available.

* First, mark the pipe as waiting for a specific wake signal.

*/

wakeBit = is_write ? BIT_WAKE_ON_WRITE : BIT_WAKE_ON_READ;

set_bit(wakeBit, &pipe->flags);

/* Tell the emulator we’re going to wait for a wake event */

spin_lock_irqsave(&dev->lock, irq_flags);

writel((unsigned long)pipe, dev->base + PIPE_REG_CHANNEL);

writel(CMD_WAKE_ON_WRITE + cmd_offset,

dev->base + PIPE_REG_COMMAND);

spin_unlock_irqrestore(&dev->lock, irq_flags);

/* Unlock the pipe, then wait for the wake signal */

mutex_unlock(&pipe->lock);

while (test_bit(wakeBit, &pipe->flags)) {

if (wait_event_interruptible(

pipe->wake_queue,

!test_bit(wakeBit, &pipe->flags))) {

ret = -ERESTARTSYS;

PIPE_W(“rw, wait_event error\n”);

goto out;

}

if (test_bit(BIT_CLOSED_ON_HOST, &pipe->flags)) {

ret = -EIO;

PIPE_W(“rw, pipe already closed\n”);

goto out;

}

}

/* Try to re-acquire the lock */

if (mutex_lock_interruptible(&pipe->lock)) {

ret = -ERESTARTSYS;

goto out;

}

/* Try the transfer again */

continue;

}

mutex_unlock(&pipe->lock);

out:

return ret;

}

static ssize_t qemu_pipe_read(struct file *filp, char __user *buffer,

size_t bufflen, loff_t *ppos)

{

return qemu_pipe_read_write(filp, buffer, bufflen, 0);

}

static ssize_t qemu_pipe_write(struct file *filp,

const char __user *buffer, size_t bufflen,

loff_t *ppos)

{

return qemu_pipe_read_write(filp, (char __user *)buffer, bufflen, 1);

}

qemu_pipe_poll,实现poll,select,epoll接口用的,没什么特殊的,标准实现方式

static unsigned int qemu_pipe_poll(struct file *filp, poll_table *wait)

{

struct qemu_pipe *pipe = filp->private_data;

struct qemu_pipe_dev *dev = pipe->dev;

unsigned long irq_flags;

unsigned int mask = 0;

int status;

mutex_lock(&pipe->lock);

poll_wait(filp, &pipe->wake_queue, wait);

spin_lock_irqsave(&dev->lock, irq_flags);

writel((unsigned long)pipe, dev->base + PIPE_REG_CHANNEL);

writel(CMD_POLL, dev->base + PIPE_REG_COMMAND);

status = readl(dev->base + PIPE_REG_STATUS);

spin_unlock_irqrestore(&dev->lock, irq_flags);

mutex_unlock(&pipe->lock);

if (status & PIPE_POLL_IN)

mask |= POLLIN | POLLRDNORM;

if (status & PIPE_POLL_OUT)

mask |= POLLOUT | POLLWRNORM;

if (status & PIPE_POLL_HUP)

mask |= POLLHUP;

if (test_bit(BIT_CLOSED_ON_HOST, &pipe->flags))

mask |= POLLERR;

return mask;

}

qemu_pipe_interrupt,中断处理函数,循环处理每一个qemu_pipe,看看是否可读 or 可写 or 关闭了,然后唤醒对应的线程

static irqreturn_t qemu_pipe_interrupt(int irq, void *dev_id)

{

struct qemu_pipe_dev *dev = dev_id;

unsigned long irq_flags;

int count = 0;

/* We’re going to read from the emulator a list of (channel,flags)

* pairs corresponding to the wake events that occured on each

* blocked pipe (i.e. channel).

*/

spin_lock_irqsave(&dev->lock, irq_flags);

for (;

标签:__,PIPE,进阶,dev,pipe,emulator,address,channel
来源: https://blog.csdn.net/m0_66144992/article/details/122741809

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