arch/powerpc/platforms/pasemi/idle.c

   1 /*
   2  * Copyright (C) 2006-2007 PA Semi, Inc
   3  *
   4  * Maintained by: Olof Johansson <olof@lixom.net>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  18  *
  19  */
  20
  21 #undef DEBUG
  22
  23 #include <linux/kernel.h>
  24 #include <linux/string.h>
  25 #include <linux/irq.h>
  26
  27 #include <asm/machdep.h>
  28 #include <asm/reg.h>
  29 #include <asm/smp.h>
  30
  31 #include "pasemi.h"
  32
  33 struct sleep_mode {
  34         char *name;
  35         void (*entry)(void);
  36 };
  37
  38 static struct sleep_mode modes[] = {
  39         { .name = "spin", .entry = &idle_spin },
  40         { .name = "doze", .entry = &idle_doze },
  41 };
  42
  43 static int current_mode = 0;
  44
  45 static int pasemi_system_reset_exception(struct pt_regs *regs)
  46 {
  47         /* If we were woken up from power savings, we need to return
  48          * to the calling function, since nip is not saved across
  49          * all modes.
  50          */
  51
  52         if (regs->msr & SRR1_WAKEMASK)
  53                 regs->nip = regs->link;
  54
  55         switch (regs->msr & SRR1_WAKEMASK) {
  56         case SRR1_WAKEDEC:
  57                 set_dec(1);
  58         case SRR1_WAKEEE:
  59                 /*
  60                  * Handle these when interrupts get re-enabled and we take
  61                  * them as regular exceptions. We are in an NMI context
  62                  * and can't handle these here.
  63                  */
  64                 break;
  65         default:
  66                 /* do system reset */
  67                 return 0;
  68         }
  69
  70         /* Set higher astate since we come out of power savings at 0 */
  71         restore_astate(hard_smp_processor_id());
  72
  73         /* everything handled */
  74         regs->msr |= MSR_RI;
  75         return 1;
  76 }
  77
  78 static int __init pasemi_idle_init(void)
  79 {
  80 #ifndef CONFIG_PPC_PASEMI_CPUFREQ
  81         printk(KERN_WARNING "No cpufreq driver, powersavings modes disabled\n");
  82         current_mode = 0;
  83 #endif
  84
  85         ppc_md.system_reset_exception = pasemi_system_reset_exception;
  86         ppc_md.power_save = modes[current_mode].entry;
  87         printk(KERN_INFO "Using PA6T idle loop (%s)\n", modes[current_mode].name);
  88
  89         return 0;
  90 }
  91 machine_late_initcall(pasemi, pasemi_idle_init);
  92
  93 static int __init idle_param(char *p)
  94 {
  95         int i;
  96         for (i = 0; i < ARRAY_SIZE(modes); i++) {
  97                 if (!strcmp(modes[i].name, p)) {
  98                         current_mode = i;
  99                         break;
 100                 }
 101         }
 102         return 0;
 103 }
 104
 105 early_param("idle", idle_param);