drivers/of/module.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Linux kernel module helpers.
   4  */
   5
   6 #include <linux/of.h>
   7 #include <linux/module.h>
   8 #include <linux/slab.h>
   9 #include <linux/string.h>
  10
  11 ssize_t of_modalias(const struct device_node *np, char *str, ssize_t len)
  12 {
  13         const char *compat;
  14         char *c;
  15         struct property *p;
  16         ssize_t csize;
  17         ssize_t tsize;
  18
  19         /*
  20          * Prevent a kernel oops in vsnprintf() -- it only allows passing a
  21          * NULL ptr when the length is also 0. Also filter out the negative
  22          * lengths...
  23          */
  24         if ((len > 0 && !str) || len < 0)
  25                 return -EINVAL;
  26
  27         /* Name & Type */
  28         /* %p eats all alphanum characters, so %c must be used here */
  29         csize = snprintf(str, len, "of:N%pOFn%c%s", np, 'T',
  30                          of_node_get_device_type(np));
  31         tsize = csize;
  32         if (csize >= len)
  33                 csize = len > 0 ? len - 1 : 0;
  34         len -= csize;
  35         str += csize;
  36
  37         of_property_for_each_string(np, "compatible", p, compat) {
  38                 csize = snprintf(str, len, "C%s", compat);
  39                 tsize += csize;
  40                 if (csize >= len)
  41                         continue;
  42                 for (c = str; c; ) {
  43                         c = strchr(c, ' ');
  44                         if (c)
  45                                 *c++ = '_';
  46                 }
  47                 len -= csize;
  48                 str += csize;
  49         }
  50
  51         return tsize;
  52 }
  53
  54 int of_request_module(const struct device_node *np)
  55 {
  56         char *str;
  57         ssize_t size;
  58         int ret;
  59
  60         if (!np)
  61                 return -ENODEV;
  62
  63         size = of_modalias(np, NULL, 0);
  64         if (size < 0)
  65                 return size;
  66
  67         /* Reserve an additional byte for the trailing '\0' */
  68         size++;
  69
  70         str = kmalloc(size, GFP_KERNEL);
  71         if (!str)
  72                 return -ENOMEM;
  73
  74         of_modalias(np, str, size);
  75         str[size - 1] = '\0';
  76         ret = request_module(str);
  77         kfree(str);
  78
  79         return ret;
  80 }
  81 EXPORT_SYMBOL_GPL(of_request_module);