linux/drivers/cpuidle/cpuidle-calxeda.c
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   1/*
   2 * Copyright 2012 Calxeda, Inc.
   3 *
   4 * Based on arch/arm/plat-mxc/cpuidle.c: #v3.7
   5 * Copyright 2012 Freescale Semiconductor, Inc.
   6 * Copyright 2012 Linaro Ltd.
   7 *
   8 * This program is free software; you can redistribute it and/or modify it
   9 * under the terms and conditions of the GNU General Public License,
  10 * version 2, as published by the Free Software Foundation.
  11 *
  12 * This program is distributed in the hope it will be useful, but WITHOUT
  13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  15 * more details.
  16 *
  17 * You should have received a copy of the GNU General Public License along with
  18 * this program.  If not, see <http://www.gnu.org/licenses/>.
  19 *
  20 * Maintainer: Rob Herring <rob.herring@calxeda.com>
  21 */
  22
  23#include <linux/cpuidle.h>
  24#include <linux/init.h>
  25#include <linux/io.h>
  26#include <linux/of.h>
  27#include <linux/time.h>
  28#include <linux/delay.h>
  29#include <linux/suspend.h>
  30#include <asm/cpuidle.h>
  31#include <asm/proc-fns.h>
  32#include <asm/smp_scu.h>
  33#include <asm/suspend.h>
  34#include <asm/cacheflush.h>
  35#include <asm/cp15.h>
  36
  37extern void highbank_set_cpu_jump(int cpu, void *jump_addr);
  38extern void *scu_base_addr;
  39
  40static inline unsigned int get_auxcr(void)
  41{
  42        unsigned int val;
  43        asm("mrc p15, 0, %0, c1, c0, 1  @ get AUXCR" : "=r" (val) : : "cc");
  44        return val;
  45}
  46
  47static inline void set_auxcr(unsigned int val)
  48{
  49        asm volatile("mcr p15, 0, %0, c1, c0, 1 @ set AUXCR"
  50          : : "r" (val) : "cc");
  51        isb();
  52}
  53
  54static noinline void calxeda_idle_restore(void)
  55{
  56        set_cr(get_cr() | CR_C);
  57        set_auxcr(get_auxcr() | 0x40);
  58        scu_power_mode(scu_base_addr, SCU_PM_NORMAL);
  59}
  60
  61static int calxeda_idle_finish(unsigned long val)
  62{
  63        /* Already flushed cache, but do it again as the outer cache functions
  64         * dirty the cache with spinlocks */
  65        flush_cache_all();
  66
  67        set_auxcr(get_auxcr() & ~0x40);
  68        set_cr(get_cr() & ~CR_C);
  69
  70        scu_power_mode(scu_base_addr, SCU_PM_DORMANT);
  71
  72        cpu_do_idle();
  73
  74        /* Restore things if we didn't enter power-gating */
  75        calxeda_idle_restore();
  76        return 1;
  77}
  78
  79static int calxeda_pwrdown_idle(struct cpuidle_device *dev,
  80                                struct cpuidle_driver *drv,
  81                                int index)
  82{
  83        highbank_set_cpu_jump(smp_processor_id(), cpu_resume);
  84        cpu_suspend(0, calxeda_idle_finish);
  85        return index;
  86}
  87
  88static struct cpuidle_driver calxeda_idle_driver = {
  89        .name = "calxeda_idle",
  90        .states = {
  91                ARM_CPUIDLE_WFI_STATE,
  92                {
  93                        .name = "PG",
  94                        .desc = "Power Gate",
  95                        .flags = CPUIDLE_FLAG_TIME_VALID,
  96                        .exit_latency = 30,
  97                        .power_usage = 50,
  98                        .target_residency = 200,
  99                        .enter = calxeda_pwrdown_idle,
 100                },
 101        },
 102        .state_count = 2,
 103};
 104
 105static int __init calxeda_cpuidle_init(void)
 106{
 107        if (!of_machine_is_compatible("calxeda,highbank"))
 108                return -ENODEV;
 109
 110        return cpuidle_register(&calxeda_idle_driver, NULL);
 111}
 112module_init(calxeda_cpuidle_init);
 113
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