arch/mips/jazz/reset.c

Source file repositories/reference/linux-study-clean/arch/mips/jazz/reset.c

File Facts

System
Linux kernel
Corpus path
arch/mips/jazz/reset.c
Extension
.c
Size
1045 bytes
Lines
58
Domain
Architecture Layer
Bucket
arch/mips
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0
/*
 * Reset a Jazz machine.
 *
 * We don't trust the firmware so we do it the classic way by poking and
 * stabbing at the keyboard controller ...
 */
#include <linux/jiffies.h>
#include <asm/jazz.h>

#define KBD_STAT_IBF		0x02	/* Keyboard input buffer full */

static void jazz_write_output(unsigned char val)
{
	int status;

	do {
		status = jazz_kh->command;
	} while (status & KBD_STAT_IBF);
	jazz_kh->data = val;
}

static void jazz_write_command(unsigned char val)
{
	int status;

	do {
		status = jazz_kh->command;
	} while (status & KBD_STAT_IBF);
	jazz_kh->command = val;
}

static unsigned char jazz_read_status(void)
{
	return jazz_kh->command;
}

static inline void kb_wait(void)
{
	unsigned long start = jiffies;
	unsigned long timeout = start + HZ/2;

	do {
		if (! (jazz_read_status() & 0x02))
			return;
	} while (time_before_eq(jiffies, timeout));
}

void jazz_machine_restart(char *command)
{
	while(1) {
		kb_wait();
		jazz_write_command(0xd1);
		kb_wait();
		jazz_write_output(0x00);
	}
}

Annotation

Implementation Notes