asmcom.s

COG-VP12864液晶屏驱动代码及对应RTC实例

#include <asm.h>
#include <mipsreg.h>
#include <cpureg.h>

/* manifest constants for com ports */
#define	COM1	0xbff80de0
#define	COM2	0xbff80be0

#define	RBR		0xbff80de0
#define	THR		0xbff80de0
#define DLL		0xbff80de0
#define IER_COM		0xbff80de1
#define DLH		0xbff80de1
#define IIR		0xbff80de2
#define FCR		0xbff80de2
#define LCR		0xbff80de3
#define MCR		0xbff80de4
#define LSR		0xbff80de5
#define MSR		0xbff80de6
#define SCR		0xbff80de7

/*
///#define	RBR		0xbff80be0
///#define	THR		0xbff80be0
///#define DLL		0xbff80be0
///#define IER		0xbff80be1
///#define DLH		0xbff80be1
///#define IIR		0xbff80be2
///#define FCR		0xbff80be2
///#define LCR		0xbff80be3
///#define MCR		0xbff80be4
///#define LSR		0xbff80be5
///#define MSR		0xbff80be6
///#define SCR		0xbff80be7
*/
/* 16550A definition */
#define CLEAR		0x00
#define DTR		0x01
#define RTS		0x02
#define CTS		0x10
#define DSR		0x20
#define CD		0x80
#define DR		0x01	/* Data Ready */
#define OR		0x02	/*Overrrun */
#define THRE		0x20	/* Transmitter Holding Register */
#define TEMT		0x40	/* Transmitter Empty */
#define Rx_ON		(DTR | RTS)
#define Tx_ON		(CD | DSR)
#define Tx_DATA_ON	(THRE | TEMT)
#define BAUD_DATA_MSB	0x00	# set divisor 12 

/*
#define BAUD_DATA_LSB	0x0C	// 9600 baud 
#define BAUD_DATA_LSB	0x5B	// 1200 baud 
#define BAUD_DATA_LSB	0x8B	// 300 baud [8 MHz crystal:(8M/2)/(6*16*BAUD_DATA)=300 baud]
*/

#define BAUD_DATA_LSB	0x18	/* 300 baud [5 MHz crystal:(5M/2)/(6*16*BAUD_DATA)=300 baud]*/
#define DIVISOR_ON	0x80
#define SERIAL_SET_DATA	0x03
#define RxRDY		0x01
#define TxRDY		0x20
#define CLEAR_DATA	0x00
#define DIS_FIFO	0x06	/* FIFO disable */
#define EN_FIFO		0x07	/* FIFO enable */
#define SCU_CMD_IDLE	0x01
    
/*
 * InitDebugSerial : void InitDebugSerial(void)
 *
 *   Initialize debug serial port.
 *
 *   Args:	none
 *   Return:	none
 */
	 LEAF(InitDebugSerial)
.set noreorder

	li	t0,LCR
	li	t1,CLEAR_DATA
	sb	t1,(t0)
	
	li	t0,IER_COM
	sb	t1,(t0)
	
	li	t0,FCR
	li	t1,EN_FIFO
	sb	t1,(t0)
	
	li	t0,LCR
	li	t1,DIVISOR_ON
	sb	t1,(t0)
	
	li	t0,DLL
	li	t1,BAUD_DATA_LSB
	sb	t1,(t0)
	
	li	t0,DLH
	li	t1,BAUD_DATA_MSB
	sb	t1,(t0)
	
	li	t0,LCR
	li	t1,SERIAL_SET_DATA
	sb	t1,(t0)
	
	li	t0,MCR
	li	t1,DTR | RTS | 8
	sb	t1,(t0)
	
    j   ra
    nop
    .end
    
/*
 * WriteDebugByte : void WriteDebugByte(char c)
 */
    LEAF(WriteDebugByte)
.set noreorder
	li	t2,THRE
	li	t1,0
1:	li	t0,LSR
	lb	t1,(t0)
	and	t1,t2		 # mask:0x20
	bne	t1,t2,1b
	nop
	
	li	t0,THR
	sb	a0,(t0)
    j   ra
    nop
    .end