drivers/staging/dream/qdsp5/evlog.h

   1 /* arch/arm/mach-msm/qdsp5/evlog.h
   2  *
   3  * simple event log debugging facility
   4  *
   5  * Copyright (C) 2008 Google, Inc.
   6  *
   7  * This software is licensed under the terms of the GNU General Public
   8  * License version 2, as published by the Free Software Foundation, and
   9  * may be copied, distributed, and modified under those terms.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  */
  17
  18 #include <linux/fs.h>
  19 #include <linux/hrtimer.h>
  20 #include <linux/debugfs.h>
  21
  22 #define EV_LOG_ENTRY_NAME(n) n##_entry
  23
  24 #define DECLARE_LOG(_name, _size, _str) \
  25 static struct ev_entry EV_LOG_ENTRY_NAME(_name)[_size]; \
  26 static struct ev_log _name = { \
  27         .name = #_name, \
  28         .strings = _str, \
  29         .num_strings = ARRAY_SIZE(_str), \
  30         .entry = EV_LOG_ENTRY_NAME(_name), \
  31         .max = ARRAY_SIZE(EV_LOG_ENTRY_NAME(_name)), \
  32 }
  33
  34 struct ev_entry {
  35         ktime_t when;
  36         uint32_t id;
  37         uint32_t arg;
  38 };
  39
  40 struct ev_log {
  41         struct ev_entry *entry;
  42         unsigned max;
  43         unsigned next;
  44         unsigned fault;
  45         const char **strings;
  46         unsigned num_strings;
  47         const char *name;
  48 };
  49
  50 static char ev_buf[4096];
  51
  52 static ssize_t ev_log_read(struct file *file, char __user *buf,
  53                            size_t count, loff_t *ppos)
  54 {
  55         struct ev_log *log = file->private_data;
  56         struct ev_entry *entry;
  57         unsigned long flags;
  58         int size = 0;
  59         unsigned n, id, max;
  60         ktime_t now, t;
  61
  62         max = log->max;
  63         now = ktime_get();
  64         local_irq_save(flags);
  65         n = (log->next - 1) & (max - 1);
  66         entry = log->entry;
  67         while (n != log->next) {
  68                 t = ktime_sub(now, entry[n].when);
  69                 id = entry[n].id;
  70                 if (id) {
  71                         const char *str;
  72                         if (id < log->num_strings)
  73                                 str = log->strings[id];
  74                         else
  75                                 str = "UNKNOWN";
  76                         size += scnprintf(ev_buf + size, 4096 - size,
  77                                           "%8d.%03d %08x %s\n",
  78                                           t.tv.sec, t.tv.nsec / 1000000,
  79                                           entry[n].arg, str);
  80                 }
  81                 n = (n - 1) & (max - 1);
  82         }
  83         log->fault = 0;
  84         local_irq_restore(flags);
  85         return simple_read_from_buffer(buf, count, ppos, ev_buf, size);
  86 }
  87
  88 static void ev_log_write(struct ev_log *log, unsigned id, unsigned arg)
  89 {
  90         struct ev_entry *entry;
  91         unsigned long flags;
  92         local_irq_save(flags);
  93
  94         if (log->fault) {
  95                 if (log->fault == 1)
  96                         goto done;
  97                 log->fault--;
  98         }
  99
 100         entry = log->entry + log->next;
 101         entry->when = ktime_get();
 102         entry->id = id;
 103         entry->arg = arg;
 104         log->next = (log->next + 1) & (log->max - 1);
 105 done:
 106         local_irq_restore(flags);
 107 }
 108
 109 static void ev_log_freeze(struct ev_log *log, unsigned count)
 110 {
 111         unsigned long flags;
 112         local_irq_save(flags);
 113         log->fault = count;
 114         local_irq_restore(flags);
 115 }
 116
 117 static int ev_log_open(struct inode *inode, struct file *file)
 118 {
 119         file->private_data = inode->i_private;
 120         return 0;
 121 }
 122
 123 static const struct file_operations ev_log_ops = {
 124         .read = ev_log_read,
 125         .open = ev_log_open,
 126         .llseek = default_llseek,
 127 };
 128
 129 static int ev_log_init(struct ev_log *log)
 130 {
 131         debugfs_create_file(log->name, 0444, 0, log, &ev_log_ops);
 132         return 0;
 133 }
 134