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