LXR linux/arch/arm/mach-imx/hotplug.c

   1/*
   2 * Copyright 2011 Freescale Semiconductor, Inc.
   3 * Copyright 2011 Linaro Ltd.
   4 *
   5 * The code contained herein is licensed under the GNU General Public
   6 * License. You may obtain a copy of the GNU General Public License
   7 * Version 2 or later at the following locations:
   8 *
   9 * http://www.opensource.org/licenses/gpl-license.html
  10 * http://www.gnu.org/copyleft/gpl.html
  11 */
  12
  13#include <linux/errno.h>
  14#include <linux/jiffies.h>
  15#include <asm/cp15.h>
  16#include <asm/proc-fns.h>
  17
  18#include "common.h"
  19
  20static inline void cpu_enter_lowpower(void)
  21{
  22        unsigned int v;
  23
  24        asm volatile(
  25                "mcr    p15, 0, %1, c7, c5, 0\n"
  26        "       mcr     p15, 0, %1, c7, c10, 4\n"
  27        /*
  28         * Turn off coherency
  29         */
  30        "       mrc     p15, 0, %0, c1, c0, 1\n"
  31        "       bic     %0, %0, %3\n"
  32        "       mcr     p15, 0, %0, c1, c0, 1\n"
  33        "       mrc     p15, 0, %0, c1, c0, 0\n"
  34        "       bic     %0, %0, %2\n"
  35        "       mcr     p15, 0, %0, c1, c0, 0\n"
  36          : "=&r" (v)
  37          : "r" (0), "Ir" (CR_C), "Ir" (0x40)
  38          : "cc");
  39}
  40
  41/*
  42 * platform-specific code to shutdown a CPU
  43 *
  44 * Called with IRQs disabled
  45 */
  46void imx_cpu_die(unsigned int cpu)
  47{
  48        cpu_enter_lowpower();
  49        /*
  50         * We use the cpu jumping argument register to sync with
  51         * imx_cpu_kill() which is running on cpu0 and waiting for
  52         * the register being cleared to kill the cpu.
  53         */
  54        imx_set_cpu_arg(cpu, ~0);
  55
  56        while (1)
  57                cpu_do_idle();
  58}
  59
  60int imx_cpu_kill(unsigned int cpu)
  61{
  62        unsigned long timeout = jiffies + msecs_to_jiffies(50);
  63
  64        while (imx_get_cpu_arg(cpu) == 0)
  65                if (time_after(jiffies, timeout))
  66                        return 0;
  67        imx_enable_cpu(cpu, false);
  68        imx_set_cpu_arg(cpu, 0);
  69        return 1;
  70}
  71