release/src-rt-6.x.4708/linux/linux-2.6.36/arch/arm/kernel/atags.c

   1 #include <linux/slab.h>
   2 #include <linux/proc_fs.h>
   3 #include <asm/setup.h>
   4 #include <asm/types.h>
   5 #include <asm/page.h>
   6
   7 struct buffer {
   8         size_t size;
   9         char data[];
  10 };
  11
  12 static int
  13 read_buffer(char* page, char** start, off_t off, int count,
  14         int* eof, void* data)
  15 {
  16         struct buffer *buffer = (struct buffer *)data;
  17
  18         if (off >= buffer->size) {
  19                 *eof = 1;
  20                 return 0;
  21         }
  22
  23         count = min((int) (buffer->size - off), count);
  24
  25         memcpy(page, &buffer->data[off], count);
  26
  27         return count;
  28 }
  29
  30 #define BOOT_PARAMS_SIZE 1536
  31 static char __initdata atags_copy[BOOT_PARAMS_SIZE];
  32
  33 void __init save_atags(const struct tag *tags)
  34 {
  35         memcpy(atags_copy, tags, sizeof(atags_copy));
  36 }
  37
  38 static int __init init_atags_procfs(void)
  39 {
  40         /*
  41          * This cannot go into save_atags() because kmalloc and proc don't work
  42          * yet when it is called.
  43          */
  44         struct proc_dir_entry *tags_entry;
  45         struct tag *tag = (struct tag *)atags_copy;
  46         struct buffer *b;
  47         size_t size;
  48
  49         if (tag->hdr.tag != ATAG_CORE) {
  50                 printk(KERN_INFO "No ATAGs?");
  51                 return -EINVAL;
  52         }
  53
  54         for (; tag->hdr.size; tag = tag_next(tag))
  55                 ;
  56
  57         /* include the terminating ATAG_NONE */
  58         size = (char *)tag - atags_copy + sizeof(struct tag_header);
  59
  60         WARN_ON(tag->hdr.tag != ATAG_NONE);
  61
  62         b = kmalloc(sizeof(*b) + size, GFP_KERNEL);
  63         if (!b)
  64                 goto nomem;
  65
  66         b->size = size;
  67         memcpy(b->data, atags_copy, size);
  68
  69         tags_entry = create_proc_read_entry("atags", 0400,
  70                         NULL, read_buffer, b);
  71
  72         if (!tags_entry)
  73                 goto nomem;
  74
  75         return 0;
  76
  77 nomem:
  78         kfree(b);
  79         printk(KERN_ERR "Exporting ATAGs: not enough memory\n");
  80
  81         return -ENOMEM;
  82 }
  83 arch_initcall(init_atags_procfs);