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 #include <asm/processor.h>
  13
  14 /* List of Systems that need fixup instructions around power-down instruction */
  15 static unsigned int pmc_leon_fixup_ids[] = {
  16         AEROFLEX_UT699,
  17         GAISLER_GR712RC,
  18         LEON4_NEXTREME1,
  19         0
  20 };
  21
  22 static int pmc_leon_need_fixup(void)
  23 {
  24         unsigned int systemid = amba_system_id >> 16;
  25         unsigned int *id;
  26
  27         id = &pmc_leon_fixup_ids[0];
  28         while (*id != 0) {
  29                 if (*id == systemid)
  30                         return 1;
  31                 id++;
  32         }
  33
  34         return 0;
  35 }
  36
  37 /*
  38  * CPU idle callback function for systems that need some extra handling
  39  * See .../arch/sparc/kernel/process.c
  40  */
  41 static void pmc_leon_idle_fixup(void)
  42 {
  43         /* Prepare an address to a non-cachable region. APB is always
  44          * none-cachable. One instruction is executed after the Sleep
  45          * instruction, we make sure to read the bus and throw away the
  46          * value by accessing a non-cachable area, also we make sure the
  47          * MMU does not get a TLB miss here by using the MMU BYPASS ASI.
  48          */
  49         register unsigned int address = (unsigned int)leon3_irqctrl_regs;
  50
  51         /* Interrupts need to be enabled to not hang the CPU */
  52         local_irq_enable();
  53
  54         __asm__ __volatile__ (
  55                 "wr     %%g0, %%asr19\n"
  56                 "lda    [%0] %1, %%g0\n"
  57                 :
  58                 : "r"(address), "i"(ASI_LEON_BYPASS));
  59 }
  60
  61 /*
  62  * CPU idle callback function
  63  * See .../arch/sparc/kernel/process.c
  64  */
  65 static void pmc_leon_idle(void)
  66 {
  67         /* Interrupts need to be enabled to not hang the CPU */
  68         local_irq_enable();
  69
  70         /* For systems without power-down, this will be no-op */
  71         __asm__ __volatile__ ("wr       %g0, %asr19\n\t");
  72 }
  73
  74 /* Install LEON Power Down function */
  75 static int __init leon_pmc_install(void)
  76 {
  77         if (sparc_cpu_model == sparc_leon) {
  78                 /* Assign power management IDLE handler */
  79                 if (pmc_leon_need_fixup())
  80                         sparc_idle = pmc_leon_idle_fixup;
  81                 else
  82                         sparc_idle = pmc_leon_idle;
  83
  84                 printk(KERN_INFO "leon: power management initialized\n");
  85         }
  86
  87         return 0;
  88 }
  89
  90 /* This driver is not critical to the boot process, don't care
  91  * if initialized late.
  92  */
  93 late_initcall(leon_pmc_install);