/************************************************************************************ * drivers/serial.c * * Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * 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 NuttX 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 #include #include #include #include #include #include #include #include #include #include /************************************************************************************ * Definitions ************************************************************************************/ /* The architecture must provide up_putc for this driver */ #ifndef CONFIG_ARCH_LOWPUTC # error "Architecture must provide up_putc() for this driver" #endif #define uart_putc(ch) up_putc(ch) /************************************************************************************ * Private Types ************************************************************************************/ /************************************************************************************ * Private Function Prototypes ************************************************************************************/ 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 int uart_ioctl(FAR 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 */ 0, /* seek */ uart_ioctl /* ioctl */ }; /************************************************************************************ * Private Functions ************************************************************************************/ /************************************************************************************ * Name: uart_takesem ************************************************************************************/ static void uart_takesem(FAR 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 ************************************************************************************/ #define uart_givesem(sem) (void)sem_post(sem) /************************************************************************************ * Name: uart_putxmitchar ************************************************************************************/ static void uart_putxmitchar(FAR 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(FAR uart_dev_t *dev, FAR 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(FAR struct file *filep, FAR const char *buffer, size_t buflen) { FAR struct inode *inode = filep->f_inode; FAR 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(FAR struct file *filep, FAR char *buffer, size_t buflen) { FAR struct inode *inode = filep->f_inode; FAR 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(FAR struct file *filep, int cmd, unsigned long arg) { FAR struct inode *inode = filep->f_inode; FAR 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(FAR struct file *filep) { FAR struct inode *inode = filep->f_inode; FAR 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) { #ifndef CONFIG_DISABLE_SIGNALS usleep(500*1000); #else up_mdelay(500); #endif } /* And wait for the TX fifo to drain */ while (!uart_txempty(dev)) { #ifndef CONFIG_DISABLE_SIGNALS usleep(500*1000); #else up_mdelay(500); #endif } /* Free the IRQ and disable the UART */ flags = irqsave(); /* Disable interrupts */ uart_detach(dev); /* Detach interrupts */ if (!dev->isconsole) /* Check for the serial console UART */ { uart_shutdown(dev); /* Disable the UART */ } 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(FAR struct file *filep) { struct inode *inode = filep->f_inode; uart_dev_t *dev = inode->i_private; ubyte tmp; 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 */ /* Increment the count of references to the device. */ tmp = dev->open_count + 1; if (tmp == 0) { /* More than 255 opens; ubyte overflows to zero */ ret = -EMFILE; } else { /* Check if this is the first time that the driver has been opened. */ if (tmp == 1) { irqstate_t flags = irqsave(); /* If this is the console, then the UART has already been initialized. */ if (!dev->isconsole) { /* Perform one time hardware initialization */ uart_setup(dev); } /* In any event, we do have to configure for interrupt driven mode of * operation. Attach the hardware IRQ(s). Hmm.. should shutdown() the * the device in the rare case that uart_attach() fails, tmp==1, and * this is not the console. */ ret = uart_attach(dev); if (ret == OK) { /* Mark the io buffers empty */ dev->xmit.head = 0; dev->xmit.tail = 0; dev->recv.head = 0; dev->recv.tail = 0; /* Enable the RX interrupt */ uart_enablerxint(dev); /* Save the new open count on success */ dev->open_count = tmp; } irqrestore(flags); } } uart_givesem(&dev->closesem); return ret; } /************************************************************************************ * Public Functions ************************************************************************************/ /************************************************************************************ * Name: uart_register * * Description: * Register serial console and serial ports. * ************************************************************************************/ int uart_register(FAR const char *path, FAR 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_driver(path, &g_serialops, 0666, dev); }