LXR linux/arch/sparc/kernel/leon

   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 */
  15unsigned int pmc_leon_fixup_ids[] = {
  16        AEROFLEX_UT699,
  17        GAISLER_GR712RC,
  18        LEON4_NEXTREME1,
  19        0
  20};
  21
  22int 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 */
  41void 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 */
  65void 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 */
  75static 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 */
  93late_initcall(leon_pmc_install);
  94