xref: /OK3568_Linux_fs/kernel/arch/mips/jazz/reset.c (revision 4882a59341e53eb6f0b4789bf948001014eff981) 
1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun  * Reset a Jazz machine.
4*4882a593Smuzhiyun  *
5*4882a593Smuzhiyun  * We don't trust the firmware so we do it the classic way by poking and
6*4882a593Smuzhiyun  * stabbing at the keyboard controller ...
7*4882a593Smuzhiyun  */
8*4882a593Smuzhiyun #include <linux/jiffies.h>
9*4882a593Smuzhiyun #include <asm/jazz.h>
10*4882a593Smuzhiyun 
11*4882a593Smuzhiyun #define KBD_STAT_IBF		0x02	/* Keyboard input buffer full */
12*4882a593Smuzhiyun 
jazz_write_output(unsigned char val)13*4882a593Smuzhiyun static void jazz_write_output(unsigned char val)
14*4882a593Smuzhiyun {
15*4882a593Smuzhiyun 	int status;
16*4882a593Smuzhiyun 
17*4882a593Smuzhiyun 	do {
18*4882a593Smuzhiyun 		status = jazz_kh->command;
19*4882a593Smuzhiyun 	} while (status & KBD_STAT_IBF);
20*4882a593Smuzhiyun 	jazz_kh->data = val;
21*4882a593Smuzhiyun }
22*4882a593Smuzhiyun 
jazz_write_command(unsigned char val)23*4882a593Smuzhiyun static void jazz_write_command(unsigned char val)
24*4882a593Smuzhiyun {
25*4882a593Smuzhiyun 	int status;
26*4882a593Smuzhiyun 
27*4882a593Smuzhiyun 	do {
28*4882a593Smuzhiyun 		status = jazz_kh->command;
29*4882a593Smuzhiyun 	} while (status & KBD_STAT_IBF);
30*4882a593Smuzhiyun 	jazz_kh->command = val;
31*4882a593Smuzhiyun }
32*4882a593Smuzhiyun 
jazz_read_status(void)33*4882a593Smuzhiyun static unsigned char jazz_read_status(void)
34*4882a593Smuzhiyun {
35*4882a593Smuzhiyun 	return jazz_kh->command;
36*4882a593Smuzhiyun }
37*4882a593Smuzhiyun 
kb_wait(void)38*4882a593Smuzhiyun static inline void kb_wait(void)
39*4882a593Smuzhiyun {
40*4882a593Smuzhiyun 	unsigned long start = jiffies;
41*4882a593Smuzhiyun 	unsigned long timeout = start + HZ/2;
42*4882a593Smuzhiyun 
43*4882a593Smuzhiyun 	do {
44*4882a593Smuzhiyun 		if (! (jazz_read_status() & 0x02))
45*4882a593Smuzhiyun 			return;
46*4882a593Smuzhiyun 	} while (time_before_eq(jiffies, timeout));
47*4882a593Smuzhiyun }
48*4882a593Smuzhiyun 
jazz_machine_restart(char * command)49*4882a593Smuzhiyun void jazz_machine_restart(char *command)
50*4882a593Smuzhiyun {
51*4882a593Smuzhiyun 	while(1) {
52*4882a593Smuzhiyun 		kb_wait();
53*4882a593Smuzhiyun 		jazz_write_command(0xd1);
54*4882a593Smuzhiyun 		kb_wait();
55*4882a593Smuzhiyun 		jazz_write_output(0x00);
56*4882a593Smuzhiyun 	}
57*4882a593Smuzhiyun }
58