LXR linux/arch/sparc/kernel/leon

   1// SPDX-License-Identifier: GPL-2.0
   2/* leon_pmc.c: LEON Power-down cpu_idle() handler
   3 *
   4 * Copyright (C) 2011 Daniel Hellstrom (daniel@gaisler.com) Aeroflex Gaisler AB
   5 */
   6
   7#include <linux/init.h>
   8#include <linux/pm.h>
   9
  10#include <asm/leon_amba.h>
  11#include <asm/cpu_type.h>
  12#include <asm/leon.h>
  13#include <asm/processor.h>
  14
  15/* List of Systems that need fixup instructions around power-down instruction */
  16static unsigned int pmc_leon_fixup_ids[] = {
  17        AEROFLEX_UT699,
  18        GAISLER_GR712RC,
  19        LEON4_NEXTREME1,
  20        0
  21};
  22
  23static int pmc_leon_need_fixup(void)
  24{
  25        unsigned int systemid = amba_system_id >> 16;
  26        unsigned int *id;
  27
  28        id = &pmc_leon_fixup_ids[0];
  29        while (*id != 0) {
  30                if (*id == systemid)
  31                        return 1;
  32                id++;
  33        }
  34
  35        return 0;
  36}
  37
  38/*
  39 * CPU idle callback function for systems that need some extra handling
  40 * See .../arch/sparc/kernel/process.c
  41 */
  42static void pmc_leon_idle_fixup(void)
  43{
  44        /* Prepare an address to a non-cachable region. APB is always
  45         * none-cachable. One instruction is executed after the Sleep
  46         * instruction, we make sure to read the bus and throw away the
  47         * value by accessing a non-cachable area, also we make sure the
  48         * MMU does not get a TLB miss here by using the MMU BYPASS ASI.
  49         */
  50        register unsigned int address = (unsigned int)leon3_irqctrl_regs;
  51
  52        /* Interrupts need to be enabled to not hang the CPU */
  53        raw_local_irq_enable();
  54
  55        __asm__ __volatile__ (
  56                "wr     %%g0, %%asr19\n"
  57                "lda    [%0] %1, %%g0\n"
  58                :
  59                : "r"(address), "i"(ASI_LEON_BYPASS));
  60}
  61
  62/*
  63 * CPU idle callback function
  64 * See .../arch/sparc/kernel/process.c
  65 */
  66static void pmc_leon_idle(void)
  67{
  68        /* Interrupts need to be enabled to not hang the CPU */
  69        raw_local_irq_enable();
  70
  71        /* For systems without power-down, this will be no-op */
  72        __asm__ __volatile__ ("wr       %g0, %asr19\n\t");
  73}
  74
  75/* Install LEON Power Down function */
  76static int __init leon_pmc_install(void)
  77{
  78        if (sparc_cpu_model == sparc_leon) {
  79                /* Assign power management IDLE handler */
  80                if (pmc_leon_need_fixup())
  81                        sparc_idle = pmc_leon_idle_fixup;
  82                else
  83                        sparc_idle = pmc_leon_idle;
  84
  85                printk(KERN_INFO "leon: power management initialized\n");
  86        }
  87
  88        return 0;
  89}
  90
  91/* This driver is not critical to the boot process, don't care
  92 * if initialized late.
  93 */
  94late_initcall(leon_pmc_install);
  95