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_set_return_ip(regs, regs->link);
41 
42 	switch (regs->msr & SRR1_WAKEMASK) {
43 	case SRR1_WAKEDEC:
44 		set_dec(1);
45 		break;
46 	case SRR1_WAKEEE:
47 		/*
48 		 * Handle these when interrupts get re-enabled and we take
49 		 * them as regular exceptions. We are in an NMI context
50 		 * and can't handle these here.
51 		 */
52 		break;
53 	default:
54 		/* do system reset */
55 		return 0;
56 	}
57 
58 	/* Set higher astate since we come out of power savings at 0 */
59 	restore_astate(hard_smp_processor_id());
60 
61 	/* everything handled */
62 	regs_set_recoverable(regs);
63 	return 1;
64 }
65 
66 static int __init pasemi_idle_init(void)
67 {
68 #ifndef CONFIG_PPC_PASEMI_CPUFREQ
69 	pr_warn("No cpufreq driver, powersavings modes disabled\n");
70 	current_mode = 0;
71 #endif
72 
73 	ppc_md.system_reset_exception = pasemi_system_reset_exception;
74 	ppc_md.power_save = modes[current_mode].entry;
75 	pr_info("Using PA6T idle loop (%s)\n", modes[current_mode].name);
76 
77 	return 0;
78 }
79 machine_late_initcall(pasemi, pasemi_idle_init);
80 
81 static int __init idle_param(char *p)
82 {
83 	int i;
84 	for (i = 0; i < ARRAY_SIZE(modes); i++) {
85 		if (!strcmp(modes[i].name, p)) {
86 			current_mode = i;
87 			break;
88 		}
89 	}
90 	return 0;
91 }
92 
93 early_param("idle", idle_param);
94