arch/arm/common/fiq_glue_setup.c

   1 /*
   2  * Copyright (C) 2010 Google, Inc.
   3  *
   4  * This software is licensed under the terms of the GNU General Public
   5  * License version 2, as published by the Free Software Foundation, and
   6  * may be copied, distributed, and modified under those terms.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #include <linux/kernel.h>
  15 #include <linux/percpu.h>
  16 #include <linux/slab.h>
  17 #include <asm/fiq.h>
  18 #include <asm/fiq_glue.h>
  19
  20 extern unsigned char fiq_glue, fiq_glue_end;
  21 extern void fiq_glue_setup(void *func, void *data, void *sp,
  22                            fiq_return_handler_t fiq_return_handler);
  23
  24 static struct fiq_handler fiq_debbuger_fiq_handler = {
  25         .name = "fiq_glue",
  26 };
  27 DEFINE_PER_CPU(void *, fiq_stack);
  28 static struct fiq_glue_handler *current_handler;
  29 static fiq_return_handler_t fiq_return_handler;
  30 static DEFINE_MUTEX(fiq_glue_lock);
  31
  32 static void fiq_glue_setup_helper(void *info)
  33 {
  34         struct fiq_glue_handler *handler = info;
  35         fiq_glue_setup(handler->fiq, handler,
  36                 __get_cpu_var(fiq_stack) + THREAD_START_SP,
  37                 fiq_return_handler);
  38 }
  39
  40 int fiq_glue_register_handler(struct fiq_glue_handler *handler)
  41 {
  42         int ret;
  43         int cpu;
  44
  45         if (!handler || !handler->fiq)
  46                 return -EINVAL;
  47
  48         mutex_lock(&fiq_glue_lock);
  49         if (fiq_stack) {
  50                 ret = -EBUSY;
  51                 goto err_busy;
  52         }
  53
  54         for_each_possible_cpu(cpu) {
  55                 void *stack;
  56                 stack = (void *)__get_free_pages(GFP_KERNEL, THREAD_SIZE_ORDER);
  57                 if (WARN_ON(!stack)) {
  58                         ret = -ENOMEM;
  59                         goto err_alloc_fiq_stack;
  60                 }
  61                 per_cpu(fiq_stack, cpu) = stack;
  62         }
  63
  64         ret = claim_fiq(&fiq_debbuger_fiq_handler);
  65         if (WARN_ON(ret))
  66                 goto err_claim_fiq;
  67
  68         current_handler = handler;
  69         on_each_cpu(fiq_glue_setup_helper, handler, true);
  70         set_fiq_handler(&fiq_glue, &fiq_glue_end - &fiq_glue);
  71
  72         mutex_unlock(&fiq_glue_lock);
  73         return 0;
  74
  75 err_claim_fiq:
  76 err_alloc_fiq_stack:
  77         for_each_possible_cpu(cpu) {
  78                 __free_pages(per_cpu(fiq_stack, cpu), THREAD_SIZE_ORDER);
  79                 per_cpu(fiq_stack, cpu) = NULL;
  80         }
  81 err_busy:
  82         mutex_unlock(&fiq_glue_lock);
  83         return ret;
  84 }
  85
  86 static void fiq_glue_update_return_handler(void (*fiq_return)(void))
  87 {
  88         fiq_return_handler = fiq_return;
  89         if (current_handler)
  90                 on_each_cpu(fiq_glue_setup_helper, current_handler, true);
  91 }
  92
  93 int fiq_glue_set_return_handler(void (*fiq_return)(void))
  94 {
  95         int ret;
  96
  97         mutex_lock(&fiq_glue_lock);
  98         if (fiq_return_handler) {
  99                 ret = -EBUSY;
 100                 goto err_busy;
 101         }
 102         fiq_glue_update_return_handler(fiq_return);
 103         ret = 0;
 104 err_busy:
 105         mutex_unlock(&fiq_glue_lock);
 106
 107         return ret;
 108 }
 109 EXPORT_SYMBOL(fiq_glue_set_return_handler);
 110
 111 int fiq_glue_clear_return_handler(void (*fiq_return)(void))
 112 {
 113         int ret;
 114
 115         mutex_lock(&fiq_glue_lock);
 116         if (WARN_ON(fiq_return_handler != fiq_return)) {
 117                 ret = -EINVAL;
 118                 goto err_inval;
 119         }
 120         fiq_glue_update_return_handler(NULL);
 121         ret = 0;
 122 err_inval:
 123         mutex_unlock(&fiq_glue_lock);
 124
 125         return ret;
 126 }
 127 EXPORT_SYMBOL(fiq_glue_clear_return_handler);
 128
 129 /**
 130  * fiq_glue_resume - Restore fiqs after suspend or low power idle states
 131  *
 132  * This must be called before calling local_fiq_enable after returning from a
 133  * power state where the fiq mode registers were lost. If a driver provided
 134  * a resume hook when it registered the handler it will be called.
 135  */
 136
 137 void fiq_glue_resume(void)
 138 {
 139         if (!current_handler)
 140                 return;
 141         fiq_glue_setup(current_handler->fiq, current_handler,
 142                 __get_cpu_var(fiq_stack) + THREAD_START_SP,
 143                 fiq_return_handler);
 144         if (current_handler->resume)
 145                 current_handler->resume(current_handler);
 146 }
 147