arch/sparc/kernel/leon_pmc.c

   1 /* leon_pmc.c: LEON Power-down cpu_idle() handler
   2  *
   3  * Copyright (C) 2011 Daniel Hellstrom (daniel@gaisler.com) Aeroflex Gaisler AB
   4  */
   5
   6 #include <linux/init.h>
   7 #include <linux/pm.h>
   8
   9 #include <asm/leon_amba.h>
  10 #include <asm/leon.h>
  11
  12 /* List of Systems that need fixup instructions around power-down instruction */
  13 unsigned int pmc_leon_fixup_ids[] = {
  14         AEROFLEX_UT699,
  15         GAISLER_GR712RC,
  16         LEON4_NEXTREME1,
  17         0
  18 };
  19
  20 int pmc_leon_need_fixup(void)
  21 {
  22         unsigned int systemid = amba_system_id >> 16;
  23         unsigned int *id;
  24
  25         id = &pmc_leon_fixup_ids[0];
  26         while (*id != 0) {
  27                 if (*id == systemid)
  28                         return 1;
  29                 id++;
  30         }
  31
  32         return 0;
  33 }
  34
  35 /*
  36  * CPU idle callback function for systems that need some extra handling
  37  * See .../arch/sparc/kernel/process.c
  38  */
  39 void pmc_leon_idle_fixup(void)
  40 {
  41         /* Prepare an address to a non-cachable region. APB is always
  42          * none-cachable. One instruction is executed after the Sleep
  43          * instruction, we make sure to read the bus and throw away the
  44          * value by accessing a non-cachable area, also we make sure the
  45          * MMU does not get a TLB miss here by using the MMU BYPASS ASI.
  46          */
  47         register unsigned int address = (unsigned int)leon3_irqctrl_regs;
  48         __asm__ __volatile__ (
  49                 "mov    %%g0, %%asr19\n"
  50                 "lda    [%0] %1, %%g0\n"
  51                 :
  52                 : "r"(address), "i"(ASI_LEON_BYPASS));
  53 }
  54
  55 /*
  56  * CPU idle callback function
  57  * See .../arch/sparc/kernel/process.c
  58  */
  59 void pmc_leon_idle(void)
  60 {
  61         /* For systems without power-down, this will be no-op */
  62         __asm__ __volatile__ ("mov      %g0, %asr19\n\t");
  63 }
  64
  65 /* Install LEON Power Down function */
  66 static int __init leon_pmc_install(void)
  67 {
  68         /* Assign power management IDLE handler */
  69         if (pmc_leon_need_fixup())
  70                 pm_idle = pmc_leon_idle_fixup;
  71         else
  72                 pm_idle = pmc_leon_idle;
  73
  74         printk(KERN_INFO "leon: power management initialized\n");
  75
  76         return 0;
  77 }
  78
  79 /* This driver is not critical to the boot process, don't care
  80  * if initialized late.
  81  */
  82 late_initcall(leon_pmc_install);