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drivers/serial/serial.c: adapt to the iovec-based api
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This would fix readv/writev issues mentioned in
#12674.
(only for this specific driver though. with this approach,
we basically have to fix every single drivers and
filesystems.)

Lightly tested on the serial console, using micropython REPL
on toywasm with esp32s3-devkit:toywasm, which used to be
suffered by the readv issue.
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@yamt
yamt committed Nov 22, 2024
1 parent 2075cc4 commit b94fb12
Showing 1 changed file with 83 additions and 22 deletions.
105 changes: 83 additions & 22 deletions drivers/serial/serial.c
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Original file line number Diff line number Diff line change
Expand Up @@ -99,6 +99,8 @@ static int uart_putxmitchar(FAR uart_dev_t *dev, int ch,
static inline ssize_t uart_irqwrite(FAR uart_dev_t *dev,
FAR const char *buffer,
size_t buflen);
static inline ssize_t uart_irqwritev(FAR uart_dev_t *dev,
FAR struct uio *uio);
static int uart_tcdrain(FAR uart_dev_t *dev,
bool cancelable, clock_t timeout);

Expand All @@ -110,11 +112,8 @@ static int uart_tcsendbreak(FAR uart_dev_t *dev,

static int uart_open(FAR struct file *filep);
static int uart_close(FAR struct file *filep);
static ssize_t uart_read(FAR struct file *filep,
FAR char *buffer, size_t buflen);
static ssize_t uart_write(FAR struct file *filep,
FAR const char *buffer,
size_t buflen);
static ssize_t uart_readv(FAR struct file *filep, FAR struct uio *uio);
static ssize_t uart_writev(FAR struct file *filep, FAR struct uio *uio);
static int uart_ioctl(FAR struct file *filep,
int cmd, unsigned long arg);
static int uart_poll(FAR struct file *filep,
Expand All @@ -141,15 +140,15 @@ static const struct file_operations g_serialops =
{
uart_open, /* open */
uart_close, /* close */
uart_read, /* read */
uart_write, /* write */
NULL, /* read */
NULL, /* write */
NULL, /* seek */
uart_ioctl, /* ioctl */
NULL, /* mmap */
NULL, /* truncate */
uart_poll, /* poll */
NULL, /* readv */
NULL /* writev */
uart_readv, /* readv */
uart_writev /* writev */
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
, uart_unlink /* unlink */
#endif
Expand Down Expand Up @@ -441,6 +440,50 @@ static inline ssize_t uart_irqwrite(FAR uart_dev_t *dev,
return buflen;
}

/****************************************************************************
* Name: uart_irqwritev
****************************************************************************/

static inline ssize_t uart_irqwritev(FAR uart_dev_t *dev,
FAR struct uio *uio)
{
ssize_t error = 0;
ssize_t total = 0;
int iovcnt = uio->uio_iovcnt;
int i;

for (i = 0; i < iovcnt; i++)
{
const struct iovec *iov = &uio->uio_iov[i];
if (iov->iov_len == 0)
{
continue;
}

ssize_t written = uart_irqwrite(dev, iov->iov_base, iov->iov_len);
if (written < 0)
{
error = written;
break;
}

if (SSIZE_MAX - total < written)
{
error = -EOVERFLOW;
break;
}

total += written;
}

if (error != 0 && total == 0)
{
return error;
}

return total;
}

/****************************************************************************
* Name: uart_tcdrain
*
Expand Down Expand Up @@ -847,11 +890,10 @@ static int uart_close(FAR struct file *filep)
}

/****************************************************************************
* Name: uart_read
* Name: uart_readv
****************************************************************************/

static ssize_t uart_read(FAR struct file *filep,
FAR char *buffer, size_t buflen)
static ssize_t uart_readv(FAR struct file *filep, FAR struct uio *uio)
{
FAR struct inode *inode = filep->f_inode;
FAR uart_dev_t *dev = inode->i_private;
Expand All @@ -862,11 +904,18 @@ static ssize_t uart_read(FAR struct file *filep,
#endif
irqstate_t flags;
ssize_t recvd = 0;
ssize_t buflen;
bool echoed = false;
int16_t tail;
char ch;
int ret;

buflen = uio_resid(uio);
if (buflen < 0)
{
return buflen;
}

/* Only one user can access rxbuf->tail at a time */

ret = nxmutex_lock(&dev->recv.lock);
Expand All @@ -885,7 +934,7 @@ static ssize_t uart_read(FAR struct file *filep,
* data from the end of the buffer.
*/

while ((size_t)recvd < buflen)
while (recvd < buflen)
{
#ifdef CONFIG_SERIAL_REMOVABLE
/* If the removable device is no longer connected, refuse to read any
Expand Down Expand Up @@ -961,7 +1010,8 @@ static ssize_t uart_read(FAR struct file *filep,
{
if (recvd > 0)
{
*buffer-- = '\0';
static const char zero = '\0';
uio_copyfrom(uio, recvd, &zero, 1);
recvd--;
if (dev->tc_lflag & ECHO)
{
Expand Down Expand Up @@ -990,7 +1040,7 @@ static ssize_t uart_read(FAR struct file *filep,

/* Store the received character */

*buffer++ = ch;
uio_copyfrom(uio, recvd, &ch, 1);
recvd++;

if (dev->tc_lflag & ECHO)
Expand Down Expand Up @@ -1325,19 +1375,24 @@ static ssize_t uart_read(FAR struct file *filep,
#endif

nxmutex_unlock(&dev->recv.lock);
if (recvd >= 0)
{
uio_advance(uio, recvd);
}

return recvd;
}

/****************************************************************************
* Name: uart_write
* Name: uart_writev
****************************************************************************/

static ssize_t uart_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen)
static ssize_t uart_writev(FAR struct file *filep, FAR struct uio *uio)
{
FAR struct inode *inode = filep->f_inode;
FAR uart_dev_t *dev = inode->i_private;
ssize_t nwritten = buflen;
ssize_t nwritten;
ssize_t buflen;
bool oktoblock;
int ret;
char ch;
Expand All @@ -1363,12 +1418,18 @@ static ssize_t uart_write(FAR struct file *filep, FAR const char *buffer,
#endif

flags = enter_critical_section();
ret = uart_irqwrite(dev, buffer, buflen);
ret = uart_irqwritev(dev, uio);
leave_critical_section(flags);

return ret;
}

buflen = nwritten = uio_resid(uio);
if (nwritten < 0)
{
return nwritten;
}

/* Only one user can access dev->xmit.head at a time */

ret = nxmutex_lock(&dev->xmit.lock);
Expand Down Expand Up @@ -1408,9 +1469,9 @@ static ssize_t uart_write(FAR struct file *filep, FAR const char *buffer,
*/

uart_disabletxint(dev);
for (; buflen; buflen--)
for (; buflen; uio_advance(uio, 1), buflen--)
{
ch = *buffer++;
uio_copyto(uio, 0, &ch, 1);
ret = OK;

/* Do output post-processing */
Expand Down

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