arch/mips/jazz/reset.c

   1 /*
   2  * Reset a Jazz machine.
   3  *
   4  * We don't trust the firmware so we do it the classic way by poking and
   5  * stabbing at the keyboard controller ...
   6  */
   7 #include <linux/jiffies.h>
   8 #include <asm/jazz.h>
   9
  10 #define KBD_STAT_IBF            0x02    /* Keyboard input buffer full */
  11
  12 static void jazz_write_output(unsigned char val)
  13 {
  14         int status;
  15
  16         do {
  17                 status = jazz_kh->command;
  18         } while (status & KBD_STAT_IBF);
  19         jazz_kh->data = val;
  20 }
  21
  22 static void jazz_write_command(unsigned char val)
  23 {
  24         int status;
  25
  26         do {
  27                 status = jazz_kh->command;
  28         } while (status & KBD_STAT_IBF);
  29         jazz_kh->command = val;
  30 }
  31
  32 static unsigned char jazz_read_status(void)
  33 {
  34         return jazz_kh->command;
  35 }
  36
  37 static inline void kb_wait(void)
  38 {
  39         unsigned long start = jiffies;
  40         unsigned long timeout = start + HZ/2;
  41
  42         do {
  43                 if (! (jazz_read_status() & 0x02))
  44                         return;
  45         } while (time_before_eq(jiffies, timeout));
  46 }
  47
  48 void jazz_machine_restart(char *command)
  49 {
  50         while(1) {
  51                 kb_wait();
  52                 jazz_write_command(0xd1);
  53                 kb_wait();
  54                 jazz_write_output(0x00);
  55         }
  56 }