xref: /kernel/linux/linux-6.6/arch/powerpc/platforms/pasemi/idle.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2006-2007 PA Semi, Inc
 *
 * Maintained by: Olof Johansson <olof@lixom.net>
 */

#undef DEBUG

#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/irq.h>

#include <asm/machdep.h>
#include <asm/reg.h>
#include <asm/smp.h>

#include "pasemi.h"

struct sleep_mode {
	char *name;
	void (*entry)(void);
};

static struct sleep_mode modes[] = {
	{ .name = "spin", .entry = &idle_spin },
	{ .name = "doze", .entry = &idle_doze },
};

static int current_mode = 0;

static int pasemi_system_reset_exception(struct pt_regs *regs)
{
	/* If we were woken up from power savings, we need to return
	 * to the calling function, since nip is not saved across
	 * all modes.
	 */

	if (regs->msr & SRR1_WAKEMASK)
		regs_set_return_ip(regs, regs->link);

	switch (regs->msr & SRR1_WAKEMASK) {
	case SRR1_WAKEDEC:
		set_dec(1);
		break;
	case SRR1_WAKEEE:
		/*
		 * Handle these when interrupts get re-enabled and we take
		 * them as regular exceptions. We are in an NMI context
		 * and can't handle these here.
		 */
		break;
	default:
		/* do system reset */
		return 0;
	}

	/* Set higher astate since we come out of power savings at 0 */
	restore_astate(hard_smp_processor_id());

	/* everything handled */
	regs_set_recoverable(regs);
	return 1;
}

static int __init pasemi_idle_init(void)
{
#ifndef CONFIG_PPC_PASEMI_CPUFREQ
	pr_warn("No cpufreq driver, powersavings modes disabled\n");
	current_mode = 0;
#endif

	ppc_md.system_reset_exception = pasemi_system_reset_exception;
	ppc_md.power_save = modes[current_mode].entry;
	pr_info("Using PA6T idle loop (%s)\n", modes[current_mode].name);

	return 0;
}
machine_late_initcall(pasemi, pasemi_idle_init);

static int __init idle_param(char *p)
{
	int i;
	for (i = 0; i < ARRAY_SIZE(modes); i++) {
		if (!strcmp(modes[i].name, p)) {
			current_mode = i;
			break;
		}
	}
	return 0;
}

early_param("idle", idle_param);