1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2006-2007 PA Semi, Inc
4  *
5  * Maintained by: Olof Johansson <olof@lixom.net>
6  */
7 
8 #undef DEBUG
9 
10 #include <linux/kernel.h>
11 #include <linux/string.h>
12 #include <linux/irq.h>
13 
14 #include <asm/machdep.h>
15 #include <asm/reg.h>
16 #include <asm/smp.h>
17 
18 #include "pasemi.h"
19 
20 struct sleep_mode {
21 	char *name;
22 	void (*entry)(void);
23 };
24 
25 static struct sleep_mode modes[] = {
26 	{ .name = "spin", .entry = &idle_spin },
27 	{ .name = "doze", .entry = &idle_doze },
28 };
29 
30 static int current_mode = 0;
31 
32 static int pasemi_system_reset_exception(struct pt_regs *regs)
33 {
34 	/* If we were woken up from power savings, we need to return
35 	 * to the calling function, since nip is not saved across
36 	 * all modes.
37 	 */
38 
39 	if (regs->msr & SRR1_WAKEMASK)
40 		regs->nip = regs->link;
41 
42 	switch (regs->msr & SRR1_WAKEMASK) {
43 	case SRR1_WAKEDEC:
44 		set_dec(1);
45 	case SRR1_WAKEEE:
46 		/*
47 		 * Handle these when interrupts get re-enabled and we take
48 		 * them as regular exceptions. We are in an NMI context
49 		 * and can't handle these here.
50 		 */
51 		break;
52 	default:
53 		/* do system reset */
54 		return 0;
55 	}
56 
57 	/* Set higher astate since we come out of power savings at 0 */
58 	restore_astate(hard_smp_processor_id());
59 
60 	/* everything handled */
61 	regs->msr |= MSR_RI;
62 	return 1;
63 }
64 
65 static int __init pasemi_idle_init(void)
66 {
67 #ifndef CONFIG_PPC_PASEMI_CPUFREQ
68 	pr_warn("No cpufreq driver, powersavings modes disabled\n");
69 	current_mode = 0;
70 #endif
71 
72 	ppc_md.system_reset_exception = pasemi_system_reset_exception;
73 	ppc_md.power_save = modes[current_mode].entry;
74 	pr_info("Using PA6T idle loop (%s)\n", modes[current_mode].name);
75 
76 	return 0;
77 }
78 machine_late_initcall(pasemi, pasemi_idle_init);
79 
80 static int __init idle_param(char *p)
81 {
82 	int i;
83 	for (i = 0; i < ARRAY_SIZE(modes); i++) {
84 		if (!strcmp(modes[i].name, p)) {
85 			current_mode = i;
86 			break;
87 		}
88 	}
89 	return 0;
90 }
91 
92 early_param("idle", idle_param);
93