serial.c

/*
 * File      : serial.c
 * This file is part of RT-Thread RTOS
 * COPYRIGHT (C) 2006, RT-Thread Development Team
 *
 * The license and distribution terms for this file may be
 * found in the file LICENSE in this distribution or at
 * http://openlab.rt-thread.com/license/LICENSE
 *
 * Change Logs:
 * Date           Author       Notes
 * 2006-03-13     Bernard      first version
 * 2009-04-20     yi.qiu      modified according bernard's stm32 version      	  	
 */

#include <rtthread.h>

#include "serial.h"

/**
 * @addtogroup S3C24X0
 */
/*@{*/

/* RT-Thread Device Interface */
/**
 * This function initializes serial
 */
static rt_err_t rt_serial_init (rt_device_t dev)
{
	struct serial_device* uart = (struct serial_device*) dev->private;

	if (!(dev->flag & RT_DEVICE_FLAG_ACTIVATED))
	{

		if (dev->flag & RT_DEVICE_FLAG_INT_RX)
		{
			rt_memset(uart->int_rx->rx_buffer, 0, 
				sizeof(uart->int_rx->rx_buffer));
			uart->int_rx->read_index = uart->int_rx->read_index = 0;
		}
		
		if (dev->flag & RT_DEVICE_FLAG_INT_TX)
		{
			rt_memset(uart->int_tx->tx_buffer, 0, 
				sizeof(uart->int_tx->tx_buffer));
			uart->int_tx->write_index = uart->int_tx->save_index = 0;
		}

		dev->flag |= RT_DEVICE_FLAG_ACTIVATED;
	}

	return RT_EOK;
}

/**
 * This function read a character from serial without interrupt enable mode
 *
 * @return the read char
 */
char rt_serial_getc(struct serial_device* uart)
{
	rt_base_t level;
	char ch = 0;
	
	/* disable interrupt */
	level = rt_hw_interrupt_disable();
	
	if (uart->int_rx->read_index != uart->int_rx->save_index)
	{
		ch = uart->int_rx->rx_buffer[uart->int_rx->read_index];

		uart->int_rx->read_index ++;
		if (uart->int_rx->read_index >= UART_RX_BUFFER_SIZE)
			uart->int_rx->read_index = 0;
	}
	
	/* enable interrupt */
	rt_hw_interrupt_enable(level);
	
	return ch;
}

/* save a char to serial buffer */
void rt_serial_savechar(struct serial_device* uart, char ch)
{
	rt_base_t level;
	
	/* disable interrupt */
	level = rt_hw_interrupt_disable();

	uart->int_rx->rx_buffer[uart->int_rx->save_index] = ch;
	uart->int_rx->save_index ++;
	if (uart->int_rx->save_index >= UART_RX_BUFFER_SIZE)
		uart->int_rx->save_index = 0;
	
	/* if the next position is read index, discard this 'read char' */
	if (uart->int_rx->save_index == uart->int_rx->read_index)
	{
		uart->int_rx->read_index ++;
		if (uart->int_rx->read_index >= UART_RX_BUFFER_SIZE)
			uart->int_rx->read_index = 0;
	}

	/* enable interrupt */
	rt_hw_interrupt_enable(level);
}

/**
 * This function will write a character to serial without interrupt enable mode
 *
 * @param c the char to write
 */
void rt_serial_putc(rt_device_t device, const char c)
{
	struct serial_device* uart = (struct serial_device*) device->private;

	/*
	 * to be polite with serial console add a line feed
	 * to the carriage return character
	 */
	if (c=='\n' && (device->flag & RT_DEVICE_FLAG_STREAM))
		rt_serial_putc(device, '\r');

	while (!(uart->uart_device->ustat & USTAT_TXB_EMPTY));
	uart->uart_device->utxh = (c & 0x1FF);
}

static rt_err_t rt_serial_open(rt_device_t dev, rt_uint16_t oflag)
{	
	RT_ASSERT(dev != RT_NULL);
	
	return RT_EOK;
}

static rt_err_t rt_serial_close(rt_device_t dev)
{	
	RT_ASSERT(dev != RT_NULL);

	return RT_EOK;
}

static rt_size_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
{
	rt_uint8_t* ptr;
	rt_err_t err_code;
	struct serial_device* uart;
	
	ptr = buffer;
	err_code = RT_EOK;
	uart = (struct serial_device*)dev->private;

	if (dev->flag & RT_DEVICE_FLAG_INT_RX)
	{
		rt_int32_t ch;

		/* interrupt mode Rx */
		while (size)
		{
			/* get a character */
			ch = rt_serial_getc(uart);
			if (ch < 0)
			{
				/* set error code */
				err_code = -RT_EEMPTY;
			}
			else
			{
				*ptr++ = ch;
				size --;
			}
		}
	}
	else
	{
		/* polling mode */
		while ((rt_uint32_t)ptr - (rt_uint32_t)buffer < size)
		{
			while (uart->uart_device->ustat & USTAT_RCV_READY)
			{
				*ptr = uart->uart_device->urxh & 0xff;
				ptr ++;
			}
		}
	}

	/* set error code */
	rt_set_errno(err_code);
	return (rt_uint32_t)ptr - (rt_uint32_t)buffer;
}

static rt_size_t rt_serial_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
{
	rt_uint8_t* ptr;
	rt_err_t err_code;
	struct serial_device* uart;
	
	err_code = RT_EOK;
	ptr = (rt_uint8_t*)buffer;
	uart = (struct serial_device*)dev->private;

	if (dev->flag & RT_DEVICE_FLAG_INT_TX)
	{
		/* interrupt mode Tx */
		while (uart->int_tx->save_index != uart->int_tx->write_index)
		{
			/* save on tx buffer */
			uart->int_tx->tx_buffer[uart->int_tx->save_index] = *ptr++;
			
			-- size;

			/* move to next position */
			uart->int_tx->save_index ++;
			
			/* wrap save index */
			if (uart->int_tx->save_index >= UART_TX_BUFFER_SIZE)
				uart->int_tx->save_index = 0;
		}
		
		/* set error code */
		if (size > 0)
			err_code = -RT_EFULL;
	}
	else
	{
		/* polling mode */
		while (size)
		{
			rt_serial_putc(dev, *ptr);
			++ptr; --size;
		}
	}	

	/* set error code */
	rt_set_errno(err_code);
	
	return (rt_uint32_t)ptr - (rt_uint32_t)buffer;
}

static rt_err_t rt_serial_control (rt_device_t dev, rt_uint8_t cmd, void *args)
{
	struct serial_device* uart;
	
	RT_ASSERT(dev != RT_NULL);

	uart = (struct serial_device*)dev->private;
	switch (cmd)
	{
	case RT_DEVICE_CTRL_SUSPEND:
		/* suspend device */
		dev->flag |= RT_DEVICE_FLAG_SUSPENDED;
		break;
	
	case RT_DEVICE_CTRL_RESUME:
		/* resume device */
		dev->flag &= ~RT_DEVICE_FLAG_SUSPENDED;
		break;
	}
	
	return RT_EOK;
}

/*
 * serial register
 */
rt_err_t rt_hw_serial_register(rt_device_t device, const char* name, rt_uint32_t flag, struct serial_device *serial)
{
	RT_ASSERT(device != RT_NULL);

	device->type 		= RT_Device_Class_Char;
	device->rx_indicate = RT_NULL;
	device->tx_complete = RT_NULL;
	device->init 		= rt_serial_init;
	device->open		= rt_serial_open;
	device->close		= rt_serial_close;
	device->read 		= rt_serial_read;
	device->write 		= rt_serial_write;
	device->control 	= rt_serial_control;
	device->private		= serial;

	/* register a character device */
	return rt_device_register(device, name, RT_DEVICE_FLAG_RDWR | flag);
}
	
/* ISR for serial interrupt */
void rt_hw_serial_isr(rt_device_t device)
{
	struct serial_device* uart = (struct serial_device*) device->private;
	
	/* interrupt mode receive */	
	RT_ASSERT(device->flag & RT_DEVICE_FLAG_INT_RX);

	/* save on rx buffer */
	while (uart->uart_device->ustat & USTAT_RCV_READY)
	{
		rt_serial_savechar(uart, uart->uart_device->urxh & 0xff);
	}

	/* invoke callback */
	if (device->rx_indicate != RT_NULL)
	{
		rt_size_t rx_length;
		
		/* get rx length */
		rx_length = uart->int_rx->read_index > uart->int_rx->save_index ?
			UART_RX_BUFFER_SIZE - uart->int_rx->read_index + uart->int_rx->save_index :
			uart->int_rx->save_index - uart->int_rx->read_index;

		device->rx_indicate(device, rx_length);
	}	
}

/*@}*/