arch/powerpc/platforms/pasemi/idle.c

   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);