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/cpu_type.h>
  11 #include <asm/leon.h>
  12
  13 /* List of Systems that need fixup instructions around power-down instruction */
  14 unsigned int pmc_leon_fixup_ids[] = {
  15         AEROFLEX_UT699,
  16         GAISLER_GR712RC,
  17         LEON4_NEXTREME1,
  18         0
  19 };
  20
  21 int pmc_leon_need_fixup(void)
  22 {
  23         unsigned int systemid = amba_system_id >> 16;
  24         unsigned int *id;
  25
  26         id = &pmc_leon_fixup_ids[0];
  27         while (*id != 0) {
  28                 if (*id == systemid)
  29                         return 1;
  30                 id++;
  31         }
  32
  33         return 0;
  34 }
  35
  36 /*
  37  * CPU idle callback function for systems that need some extra handling
  38  * See .../arch/sparc/kernel/process.c
  39  */
  40 void pmc_leon_idle_fixup(void)
  41 {
  42         /* Prepare an address to a non-cachable region. APB is always
  43          * none-cachable. One instruction is executed after the Sleep
  44          * instruction, we make sure to read the bus and throw away the
  45          * value by accessing a non-cachable area, also we make sure the
  46          * MMU does not get a TLB miss here by using the MMU BYPASS ASI.
  47          */
  48         register unsigned int address = (unsigned int)leon3_irqctrl_regs;
  49         __asm__ __volatile__ (
  50                 "mov    %%g0, %%asr19\n"
  51                 "lda    [%0] %1, %%g0\n"
  52                 :
  53                 : "r"(address), "i"(ASI_LEON_BYPASS));
  54 }
  55
  56 /*
  57  * CPU idle callback function
  58  * See .../arch/sparc/kernel/process.c
  59  */
  60 void pmc_leon_idle(void)
  61 {
  62         /* For systems without power-down, this will be no-op */
  63         __asm__ __volatile__ ("mov      %g0, %asr19\n\t");
  64 }
  65
  66 /* Install LEON Power Down function */
  67 static int __init leon_pmc_install(void)
  68 {
  69         if (sparc_cpu_model == sparc_leon) {
  70                 /* Assign power management IDLE handler */
  71                 if (pmc_leon_need_fixup())
  72                         pm_idle = pmc_leon_idle_fixup;
  73                 else
  74                         pm_idle = pmc_leon_idle;
  75
  76                 printk(KERN_INFO "leon: power management initialized\n");
  77         }
  78
  79         return 0;
  80 }
  81
  82 /* This driver is not critical to the boot process, don't care
  83  * if initialized late.
  84  */
  85 late_initcall(leon_pmc_install);