/* armboot_start is defined in the board-specific linker script */
mem_malloc_init (TEXT_BASE - CONFIG_SYS_MALLOC_LEN, CONFIG_SYS_MALLOC_LEN);
ptr = (char *)malloc(MALLOC_SIZE);
strncpy(ptr, "Hello World!\n", MALLOC_SIZE);
printf("Malloc address: %p, string: %s\n", ptr, ptr);
free(ptr);
yaffs_test(YAFFSFS_MNT_POINT);
hang:
while(1)
;
return 0;
}
首先是初始化串口，console_serial_init()函数如下：
位置：yaffs2/bsp/s3c_board.h
#define CONSOLE_BAUDRATE 115200
#define CONSOLE_SERIAL S3C2440_UART0
其中S3C2440_UART0在文件yaffs2/bsp/s3c2440.h中定义：
enum s3c2440_uarts_nr {
S3C2440_UART0 = 0,
S3C2440_UART1 = 1,
S3C2440_UART2 = 2
};
#define console_serial_init() s3c2440_serial_init(CONSOLE_BAUDRATE, CONSOLE_SERIAL)
即--> console_serial_init()-->s3c2440_serial_init()如下：
int s3c2440_serial_init(unsigned int baudrate, int index)
{
struct s3c2440_uart *uart = s3c2440_get_base_uart(index);
/* FIFO enable, Tx/Rx FIFO clear */
uart->UFCON = 0x07;
uart->UMCON = 0x0;
/* Normal,No parity,1 stop,8 bit */
uart->ULCON = 0x3;
/*
* tx=level,rx=edge,disable timeout int.,enable rx error int.,
* normal,interrupt or polling
*/
uart->UCON = (1<<8) | (1<<2) | (1<<0);
// uart->UMCON = 0x1; /* RTS up */
s3c2440_set_baudrate(baudrate, index);
return (0);
}
设置波特率函数s3c2440_set_baudrate()
void s3c2440_set_baudrate(unsigned int baudrate, int index)
{
struct s3c2440_uart *uart = s3c2440_get_base_uart(index);
unsigned int reg = 0;
int i;
reg = s3c2440_get_pclk() / (16 * baudrate) - 1;
uart->UBRDIV = reg;
for (i = 0; i < 100; i++);
}
返回到bootstrap_main()函数中去，看下printf()函数如何将打印信息通过串口显示出来。
#define CFG_PBSIZE 1024 /* Print Buffer Size */
void printf(const char *fmt, ...)
{
va_list args;
uint i;
char printbuffer[CFG_PBSIZE];
va_start(args, fmt);
/* For this to work, printbuffer must be larger than
* anything we ever want to print.
*/
i = vsprintf(printbuffer, fmt, args);
va_end(args);
console_serial_puts(printbuffer);
}
调用函数console_serial_puts()函数，如下：
#define console_serial_puts(s) s3c2440_serial_puts(s, CONSOLE_SERIAL)
void s3c2440_serial_puts(const char *s, int index)
{
while (*s)
{
if (*s == '\n') /* If \n, also do \r */
s3c2440_serial_putc('\r', index);
s3c2440_serial_putc (*s++, index);
}
}
调用函数s3c2440_serial_putc()函数，如下：
/*
* Output a single byte to the serial port.
*/
void s3c2440_serial_putc (char c, int index)
{
struct s3c2440_uart *uart = s3c2440_get_base_uart(index);