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
13 static 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
23 static 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
33 static unsigned char jazz_read_status(void)
34 {
35 return jazz_kh->command;
36 }
37
38 static 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
49 void 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
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