rt-thread/bsp/lpc1114/uart.c

#include <rthw.h>
#include <rtthread.h>
#include <CMSIS/LPC11xx.h>

#define IER_RBR		0x01
#define IER_THRE	0x02
#define IER_RLS		0x04

#define IIR_PEND	0x01
#define IIR_RLS		0x03
#define IIR_RDA		0x02
#define IIR_CTI		0x06
#define IIR_THRE	0x01

#define LSR_RDR		0x01
#define LSR_OE		0x02
#define LSR_PE		0x04
#define LSR_FE		0x08
#define LSR_BI		0x10
#define LSR_THRE	0x20
#define LSR_TEMT	0x40
#define LSR_RXFE	0x80

/**
 * @addtogroup LPC11xx
 */

/*@{*/
#if defined(RT_USING_UART) && defined(RT_USING_DEVICE)

#define UART_BAUDRATE   115200
struct rt_uart_lpc
{
	struct rt_device parent;

	/* buffer for reception */
	rt_uint8_t read_index, save_index;
	rt_uint8_t rx_buffer[RT_UART_RX_BUFFER_SIZE];
}uart_device;

void UART_IRQHandler(void)
{
	rt_ubase_t level, iir;
    struct rt_uart_lpc* uart = &uart_device;

    /* read IIR and clear it */
	iir = LPC_UART->IIR;

	iir >>= 1;			    /* skip pending bit in IIR */
	iir &= 0x07;			/* check bit 1~3, interrupt identification */

	if (iir == IIR_RDA)	    /* Receive Data Available */
	{
		/* Receive Data Available */
        uart->rx_buffer[uart->save_index] = LPC_UART->RBR;

        level = rt_hw_interrupt_disable();
		uart->save_index ++;
        if (uart->save_index >= RT_UART_RX_BUFFER_SIZE)
            uart->save_index = 0;
        rt_hw_interrupt_enable(level);

		/* invoke callback */
		if(uart->parent.rx_indicate != RT_NULL)
		{
		    rt_size_t length;
		    if (uart->read_index > uart->save_index)
                length = RT_UART_RX_BUFFER_SIZE - uart->read_index + uart->save_index;
            else
                length = uart->save_index - uart->read_index;

            uart->parent.rx_indicate(&uart->parent, length);
		}
	}

	return;
}

static rt_err_t rt_uart_init (rt_device_t dev)
{
	rt_uint32_t Fdiv;
	rt_uint32_t regVal;

	/* Init UART Hardware */
	LPC_IOCON->PIO1_6 &= ~0x07;    /*  UART I/O config */
	LPC_IOCON->PIO1_6 |= 0x01;     /* UART RXD */
	LPC_IOCON->PIO1_7 &= ~0x07;
	LPC_IOCON->PIO1_7 |= 0x01;     /* UART TXD */

	/* Enable UART clock */
	LPC_SYSCON->SYSAHBCLKCTRL |= (1<<12);
	LPC_SYSCON->UARTCLKDIV = 0x1;     /* divided by 1 */

	LPC_UART->LCR = 0x83;             /* 8 bits, no Parity, 1 Stop bit */
	regVal = LPC_SYSCON->UARTCLKDIV;

    /* set baudrate */
    regVal = LPC_SYSCON->UARTCLKDIV;
    Fdiv = (((SystemCoreClock/LPC_SYSCON->SYSAHBCLKDIV)/regVal)/16)/UART_BAUDRATE ;

	LPC_UART->DLM = Fdiv / 256;
	LPC_UART->DLL = Fdiv % 256;
	LPC_UART->LCR = 0x03;		/* DLAB = 0 */
	LPC_UART->FCR = 0x07;		/* Enable and reset TX and RX FIFO. */

	/* Read to clear the line status. */
	regVal = LPC_UART->LSR;

	/* Ensure a clean start, no data in either TX or RX FIFO. */
	while (( LPC_UART->LSR & (LSR_THRE|LSR_TEMT)) != (LSR_THRE|LSR_TEMT) );
	while ( LPC_UART->LSR & LSR_RDR )
	{
		regVal = LPC_UART->RBR;	/* Dump data from RX FIFO */
	}

	LPC_UART->IER = IER_RBR | IER_THRE | IER_RLS;	/* Enable UART interrupt */

	return RT_EOK;
}

static rt_err_t rt_uart_open(rt_device_t dev, rt_uint16_t oflag)
{
	RT_ASSERT(dev != RT_NULL);
	if (dev->flag & RT_DEVICE_FLAG_INT_RX)
	{
		/* Enable the UART Interrupt */
		NVIC_EnableIRQ(UART_IRQn);
	}

	return RT_EOK;
}

static rt_err_t rt_uart_close(rt_device_t dev)
{
	RT_ASSERT(dev != RT_NULL);
	if (dev->flag & RT_DEVICE_FLAG_INT_RX)
	{
		/* Disable the UART Interrupt */
		NVIC_DisableIRQ(UART_IRQn);
	}

	return RT_EOK;
}

static rt_size_t rt_uart_read(rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
{
	rt_uint8_t* ptr;
	struct rt_uart_lpc *uart = (struct rt_uart_lpc*)dev;
	RT_ASSERT(uart != RT_NULL);

	/* point to buffer */
	ptr = (rt_uint8_t*) buffer;
	if (dev->flag & RT_DEVICE_FLAG_INT_RX)
	{
		while (size)
		{
			/* interrupt receive */
			rt_base_t level;

			/* disable interrupt */
			level = rt_hw_interrupt_disable();
			if (uart->read_index != uart->save_index)
			{
				*ptr = uart->rx_buffer[uart->read_index];

				uart->read_index ++;
				if (uart->read_index >= RT_UART_RX_BUFFER_SIZE)
					uart->read_index = 0;
			}
			else
			{
				/* no data in rx buffer */

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

			/* enable interrupt */
			rt_hw_interrupt_enable(level);

			ptr ++;
			size --;
		}

		return (rt_uint32_t)ptr - (rt_uint32_t)buffer;
	}

	return 0;
}

static rt_size_t rt_uart_write(rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
{
	char *ptr;
	ptr = (char*)buffer;

	if (dev->flag & RT_DEVICE_FLAG_STREAM)
	{
		/* stream mode */
		while (size)
		{
			if (*ptr == '\n')
			{
				/* THRE status, contain valid data */
				while ( !(LPC_UART->LSR & LSR_THRE) );
				/* write data */
				LPC_UART->THR = '\r';
			}

			/* THRE status, contain valid data */
			while ( !(LPC_UART->LSR & LSR_THRE) );	
			/* write data */
			LPC_UART->THR = *ptr;
			
			ptr ++;
			size --;
		}
	}
	else
	{
	while ( size != 0 )
	{
		/* THRE status, contain valid data */
		while ( !(LPC_UART->LSR & LSR_THRE) );

		/* write data */
		LPC_UART->THR = *ptr;

		ptr++;
		size--;
	}
	}

	return (rt_size_t) ptr - (rt_size_t) buffer;
}

void rt_hw_uart_init(void)
{
	struct rt_uart_lpc* uart;

	/* get uart device */
	uart = &uart_device;

	/* device initialization */
	uart->parent.type = RT_Device_Class_Char;
	rt_memset(uart->rx_buffer, 0, sizeof(uart->rx_buffer));
	uart->read_index = uart->save_index = 0;

	uart->parent.rx_indicate = RT_NULL;
	uart->parent.tx_complete = RT_NULL;

	/* device interface */
	uart->parent.init 	    = rt_uart_init;
	uart->parent.open 	    = rt_uart_open;
	uart->parent.close      = rt_uart_close;
	uart->parent.read 	    = rt_uart_read;
	uart->parent.write      = rt_uart_write;
	uart->parent.control    = RT_NULL;
	uart->parent.user_data  = RT_NULL;

	rt_device_register(&uart->parent,
		"uart", RT_DEVICE_FLAG_RDWR | RT_DEVICE_FLAG_STREAM | RT_DEVICE_FLAG_INT_RX);
}
#endif /* end of UART */

/*@}*/