/************************************************************************************
* serial.c
*
* Copyright (C) 2007 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name Gregory Nutt nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
************************************************************************************/
/************************************************************************************
* Included Files
************************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <unistd.h>
#include <semaphore.h>
#include <string.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/irq.h>
#include <nuttx/arch.h>
#include <nuttx/fs.h>
#include <nuttx/serial.h>
/************************************************************************************
* Definitions
************************************************************************************/
#ifdef CONFIG_HAVE_LOWPUTC
# define uart_putc(ch) up_lowputc(ch);
#else
# define uart_putc(ch) up_putc(ch);
#endif
/************************************************************************************
* Private Types
************************************************************************************/
/************************************************************************************
* Private Function Prototypes
************************************************************************************/
static int uart_open(struct file *filep);
static int uart_close(struct file *filep);
static ssize_t uart_read(struct file *filep, char *buffer, size_t buflen);
static ssize_t uart_write(struct file *filep, const char *buffer, size_t buflen);
static int uart_ioctl(struct file *filep, int cmd, unsigned long arg);
/************************************************************************************
* Private Variables
************************************************************************************/
struct file_operations g_serialops =
{
uart_open, /* open */
uart_close, /* close */
uart_read, /* read */
uart_write, /* write */
uart_ioctl /* ioctl */
};
/************************************************************************************
* Private Functions
************************************************************************************/
/************************************************************************************
* Name: uart_takesem
************************************************************************************/
static void uart_takesem(sem_t *sem)
{
while (sem_wait(sem) != 0)
{
/* The only case that an error should occur here is if
* the wait was awakened by a signal.
*/
ASSERT(*get_errno_ptr() == EINTR);
}
}
/************************************************************************************
* Name: uart_givesem
************************************************************************************/
static inline void uart_givesem(sem_t *sem)
{
(void)sem_post(sem);
}
/************************************************************************************
* Name: uart_putxmitchar
************************************************************************************/
static void uart_putxmitchar(uart_dev_t *dev, int ch)
{
int nexthead = dev->xmit.head + 1;
if (nexthead >= dev->xmit.size)
{
nexthead = 0;
}
for(;;)
{
if (nexthead != dev->xmit.tail)
{
dev->xmit.buffer[dev->xmit.head] = ch;
dev->xmit.head = nexthead;
return;
}
else
{
/* Inform the interrupt level logic that we are waiting */
dev->xmitwaiting = TRUE;
/* Wait for some characters to be sent from the buffer
* with the TX interrupt enabled. When the TX interrupt
* is enabled, uart_xmitchars should execute and remove
* some of the data from the TX buffer.
*/
uart_enabletxint(dev);
uart_takesem(&dev->xmitsem);
uart_disabletxint(dev);
}
}
}
/************************************************************************************
* Name: uart_irqwrite
************************************************************************************/
static ssize_t uart_irqwrite(uart_dev_t *dev, const char *buffer, size_t buflen)
{
ssize_t ret = buflen;
/* Force each character through the low level interface */
for (; buflen; buflen--)
{
int ch = *buffer++;
uart_putc(ch);
/* If this is the console, then we should replace LF with LF-CR */
if (ch == '\n')
{
uart_putc('\r');
}
}
return ret;
}
/************************************************************************************
* Name: uart_write
************************************************************************************/
static ssize_t uart_write(struct file *filep, const char *buffer, size_t buflen)
{
struct inode *inode = filep->f_inode;
uart_dev_t *dev = inode->i_private;
ssize_t ret = buflen;
/* We may receive console writes through this path from
* interrupt handlers and from debug output in the IDLE task!
* In these cases, we will need to do things a little
* differently.
*/
if (up_interrupt_context() || getpid() == 0)
{
if (dev->isconsole)
{
irqstate_t flags = irqsave();
ret = uart_irqwrite(dev, buffer, buflen);
irqrestore(flags);
return ret;
}
else
{
return ERROR;
}
}
/* Only one user can be accessing dev->xmit.head at once */
uart_takesem(&dev->xmit.sem);
/* Loop while we still have data to copy to the transmit buffer.
* we add data to the head of the buffer; uart_xmitchars takes the
* data from the end of the buffer.
*/
uart_disabletxint(dev);
for (; buflen; buflen--)
{
int ch = *buffer++;
/* Put the character into the transmit buffer */
uart_putxmitchar(dev, ch);
/* If this is the console, then we should replace LF with LF-CR */
if (dev->isconsole && ch == '\n')
{
uart_putxmitchar(dev, '\r');
}
}
if (dev->xmit.head != dev->xmit.tail)
{
uart_enabletxint(dev);
}
uart_givesem(&dev->xmit.sem);
return ret;
}
/************************************************************************************
* Name: uart_read
************************************************************************************/
static ssize_t uart_read(struct file *filep, char *buffer, size_t buflen)
{
struct inode *inode = filep->f_inode;
uart_dev_t *dev = inode->i_private;
ssize_t ret = buflen;
/* Only one user can be accessing dev->recv.tail at once */
uart_takesem(&dev->recv.sem);
/* Loop while we still have data to copy to the receive buffer.
* we add data to the head of the buffer; uart_xmitchars takes the
* data from the end of the buffer.
*/
uart_disablerxint(dev);
while (buflen)
{
if (dev->recv.head != dev->recv.tail)
{
*buffer++ = dev->recv.buffer[dev->recv.tail];
buflen--;
if (++(dev->recv.tail) >= dev->recv.size)
{
dev->recv.tail = 0;
}
}
else
{
/* Wait for some characters to be sent from the buffer
* with the TX interrupt disabled.
*/
dev->recvwaiting = TRUE;
uart_enablerxint(dev);
uart_takesem(&dev->recvsem);
uart_disablerxint(dev);
}
}
uart_enablerxint(dev);
uart_givesem(&dev->recv.sem);
return ret;
}
/************************************************************************************
* Name: uart_ioctl
************************************************************************************/
static int uart_ioctl(struct file *filep, int cmd, unsigned long arg)
{
struct inode *inode = filep->f_inode;
uart_dev_t *dev = inode->i_private;
return dev->ops->ioctl(filep, cmd, arg);
}
/************************************************************************************
* Name: uart_close
*
* Description:
* This routine is called when the serial port gets closed.
* It waits for the last remaining data to be sent.
*
************************************************************************************/
static int uart_close(struct file *filep)
{
struct inode *inode = filep->f_inode;
uart_dev_t *dev = inode->i_private;
irqstate_t flags;
uart_takesem(&dev->closesem);
if (dev->open_count > 1)
{
dev->open_count--;
uart_givesem(&dev->closesem);
return OK;
}
/* There are no more references to the port */
dev->open_count = 0;
/* Stop accepting input */
uart_disablerxint(dev);
/* Now we wait for the transmit buffer to clear */
while (dev->xmit.head != dev->xmit.tail)
{
usleep(500*1000);
}
/* And wait for the TX fifo to drain */
while (!uart_txfifoempty(dev))
{
usleep(500*1000);
}
/* Free the IRQ and disable the UART */
flags = irqsave(); /* Disable interrupts */
up_disable_irq(dev->irq);
irq_detach(dev->irq);
uart_shutdown(dev);
irqrestore(flags);
uart_givesem(&dev->closesem);
return OK;
}
/************************************************************************************
* Name: uart_open
*
* Description:
* This routine is called whenever a serial port is opened.
*
************************************************************************************/
static int uart_open(struct file *filep)
{
struct inode *inode = filep->f_inode;
uart_dev_t *dev = inode->i_private;
int ret = OK;
/* If the port is the middle of closing, wait until the close
* is finished
*/
uart_takesem(&dev->closesem);
/* Start up serial port */
if (++dev->open_count == 1)
{
irqstate_t flags = irqsave();
/* If this is the console, then the UART has already
* been initialized.
*/
if (!dev->isconsole)
{
uart_setup(dev);
}
/* But, in any event, we do have to configure for
* interrupt driven mode of operation.
*/
/* Attache and enabled the IRQ */
ret = irq_attach(dev->irq, dev->ops->handler);
if (ret == OK)
{
/* Mark the io buffers empty */
dev->xmit.head = 0;
dev->xmit.tail = 0;
dev->recv.head = 0;
dev->recv.tail = 0;
/* Finally, enable interrupts */
up_enable_irq(dev->irq);
uart_enablerxint(dev);
}
irqrestore(flags);
}
uart_givesem(&dev->closesem);
return ret;
}
/************************************************************************************
* Public Functions
************************************************************************************/
/************************************************************************************
* Name: uart_register
*
* Description:
* Register serial console and serial ports.
*
************************************************************************************/
int uart_register(const char *path, uart_dev_t *dev)
{
sem_init(&dev->xmit.sem, 0, 1);
sem_init(&dev->recv.sem, 0, 1);
sem_init(&dev->closesem, 0, 1);
sem_init(&dev->xmitsem, 0, 0);
sem_init(&dev->recvsem, 0, 0);
dbg("Registering %s\n", path);
return register_inode(path, &g_serialops, 0666, dev);
}
/************************************************************************************
* Name: uart_xmitchars
*
* Description:
* This function is called from the UART interrupt handler when an interrupt
* is received indicating that there is more space in the transmit FIFO. This
* function will send characters from the tail of the xmit buffer while the driver
* write() logic adds data to the head of the xmit buffer.
*
************************************************************************************/
void uart_xmitchars(uart_dev_t *dev)
{
/* Send while we still have data & room in the fifo */
while (dev->xmit.head != dev->xmit.tail && uart_txfifonotfull(dev))
{
uart_send(dev, dev->xmit.buffer[dev->xmit.tail]);
if (++(dev->xmit.tail) >= dev->xmit.size)
{
dev->xmit.tail = 0;
}
if (dev->xmitwaiting)
{
dev->xmitwaiting = FALSE;
uart_givesem(&dev->xmitsem);
}
}
/* When all of the characters have been sent from the buffer
* disable the TX interrupt.
*/
if (dev->xmit.head == dev->xmit.tail)
{
uart_disabletxint(dev);
}
}
/************************************************************************************
* Name: uart_receivechars
*
* Description:
* This function is called from the UART interrupt handler when an interrupt
* is received indicating that are bytes available in the receive fifo. This
* function will add chars to head of receive buffer. Driver read() logic will take
* characters from the tail of the buffer.
*
************************************************************************************/
void uart_recvchars(uart_dev_t *dev)
{
unsigned int status;
int nexthead = dev->recv.head + 1;
if (nexthead >= dev->recv.size)
{
nexthead = 0;
}
while (nexthead != dev->recv.tail && uart_rxfifonotempty(dev))
{
dev->recv.buffer[dev->recv.head] = uart_receive(dev, &status);
dev->recv.head = nexthead;
if (++nexthead >= dev->recv.size)
{
nexthead = 0;
}
if (dev->recvwaiting)
{
dev->recvwaiting = FALSE;
uart_givesem(&dev->recvsem);
}
}
}
