arch/mips/boot/compressed/uart-16550.c

   1 /*
   2  * 16550 compatible uart based serial debug support for zboot
   3  */
   4
   5 #include <linux/types.h>
   6 #include <linux/serial_reg.h>
   7 #include <linux/init.h>
   8
   9 #include <asm/addrspace.h>
  10
  11 #if defined(CONFIG_MACH_LOONGSON) || defined(CONFIG_MIPS_MALTA)
  12 #define UART_BASE 0x1fd003f8
  13 #define PORT(offset) (CKSEG1ADDR(UART_BASE) + (offset))
  14 #endif
  15
  16 #ifdef CONFIG_AR7
  17 #include <ar7.h>
  18 #define PORT(offset) (CKSEG1ADDR(AR7_REGS_UART0) + (4 * offset))
  19 #endif
  20
  21 #ifndef PORT
  22 #error please define the serial port address for your own machine
  23 #endif
  24
  25 static inline unsigned int serial_in(int offset)
  26 {
  27         return *((char *)PORT(offset));
  28 }
  29
  30 static inline void serial_out(int offset, int value)
  31 {
  32         *((char *)PORT(offset)) = value;
  33 }
  34
  35 void putc(char c)
  36 {
  37         int timeout = 1024;
  38
  39         while (((serial_in(UART_LSR) & UART_LSR_THRE) == 0) && (timeout-- > 0))
  40                 ;
  41
  42         serial_out(UART_TX, c);
  43 }