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 <asm/cacheflush.h>
  15 #include <asm/cp15.h>
  16 #include <mach/common.h>
  17
  18 int platform_cpu_kill(unsigned int cpu)
  19 {
  20         return 1;
  21 }
  22
  23 static inline void cpu_enter_lowpower(void)
  24 {
  25         unsigned int v;
  26
  27         flush_cache_all();
  28         asm volatile(
  29                 "mcr    p15, 0, %1, c7, c5, 0\n"
  30         "       mcr     p15, 0, %1, c7, c10, 4\n"
  31         /*
  32          * Turn off coherency
  33          */
  34         "       mrc     p15, 0, %0, c1, c0, 1\n"
  35         "       bic     %0, %0, %3\n"
  36         "       mcr     p15, 0, %0, c1, c0, 1\n"
  37         "       mrc     p15, 0, %0, c1, c0, 0\n"
  38         "       bic     %0, %0, %2\n"
  39         "       mcr     p15, 0, %0, c1, c0, 0\n"
  40           : "=&r" (v)
  41           : "r" (0), "Ir" (CR_C), "Ir" (0x40)
  42           : "cc");
  43 }
  44
  45 static inline void cpu_leave_lowpower(void)
  46 {
  47         unsigned int v;
  48
  49         asm volatile(
  50                 "mrc    p15, 0, %0, c1, c0, 0\n"
  51         "       orr     %0, %0, %1\n"
  52         "       mcr     p15, 0, %0, c1, c0, 0\n"
  53         "       mrc     p15, 0, %0, c1, c0, 1\n"
  54         "       orr     %0, %0, %2\n"
  55         "       mcr     p15, 0, %0, c1, c0, 1\n"
  56           : "=&r" (v)
  57           : "Ir" (CR_C), "Ir" (0x40)
  58           : "cc");
  59 }
  60
  61 /*
  62  * platform-specific code to shutdown a CPU
  63  *
  64  * Called with IRQs disabled
  65  */
  66 void platform_cpu_die(unsigned int cpu)
  67 {
  68         cpu_enter_lowpower();
  69         imx_enable_cpu(cpu, false);
  70         cpu_do_idle();
  71         cpu_leave_lowpower();
  72
  73         /* We should never return from idle */
  74         panic("cpu %d unexpectedly exit from shutdown\n", cpu);
  75 }
  76
  77 int platform_cpu_disable(unsigned int cpu)
  78 {
  79         /*
  80          * we don't allow CPU 0 to be shutdown (it is still too special
  81          * e.g. clock tick interrupts)
  82          */
  83         return cpu == 0 ? -EPERM : 0;
  84 }