target/linux/generic/pending-5.15/682-of_net-add-mac-address-increment-support.patch

   1 From 844c273286f328acf0dab5fbd5d864366b4904dc Mon Sep 17 00:00:00 2001
   2 From: Ansuel Smith <ansuelsmth@gmail.com>
   3 Date: Tue, 30 Mar 2021 18:21:14 +0200
   4 Subject: [PATCH] of_net: add mac-address-increment support
   5
   6 Lots of embedded devices use the mac-address of other interface
   7 extracted from nvmem cells and increments it by one or two. Add two
   8 bindings to integrate this and directly use the right mac-address for
   9 the interface. Some example are some routers that use the gmac
  10 mac-address stored in the art partition and increments it by one for the
  11 wifi. mac-address-increment-byte bindings is used to tell what byte of
  12 the mac-address has to be increased (if not defined the last byte is
  13 increased) and mac-address-increment tells how much the byte decided
  14 early has to be increased.
  15
  16 Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
  17 ---
  18  net/core/of_net.c | 43 +++++++++++++++++++++++++++++++++++++++----
  19  1 file changed, 39 insertions(+), 4 deletions(-)
  20
  21 --- a/net/core/of_net.c
  22 +++ b/net/core/of_net.c
  23 @@ -119,10 +119,19 @@ static int of_get_mac_addr_nvmem(struct
  24   * this case, the real MAC is in 'local-mac-address', and 'mac-address' exists
  25   * but is all zeros.
  26   *
  27 + * DT can tell the system to increment the mac-address after is extracted by
  28 + * using:
  29 + * - mac-address-increment to decide how much to increase. The value WILL
  30 + *   overflow to other bytes if the increment is over 255 or the total
  31 + *   increment will exceed 255 of the current byte.
  32 + *   (example 00:01:02:03:04:ff + 1 == 00:01:02:03:05:00)
  33 + *   (example 00:01:02:03:04:fe + 5 == 00:01:02:03:05:03)
  34 + *
  35   * Return: 0 on success and errno in case of error.
  36  */
  37  int of_get_mac_address(struct device_node *np, u8 *addr)
  38  {
  39 +       u32 mac_inc, mac_val;
  40         int ret;
  41
  42         if (!np)
  43 @@ -130,17 +139,33 @@ int of_get_mac_address(struct device_nod
  44
  45         ret = of_get_mac_addr(np, "mac-address", addr);
  46         if (!ret)
  47 -               return 0;
  48 +               goto found;
  49
  50         ret = of_get_mac_addr(np, "local-mac-address", addr);
  51         if (!ret)
  52 -               return 0;
  53 +               goto found;
  54
  55         ret = of_get_mac_addr(np, "address", addr);
  56         if (!ret)
  57 -               return 0;
  58 +               goto found;
  59 +
  60 +       ret = of_get_mac_addr_nvmem(np, addr);
  61 +       if (ret)
  62 +               return ret;
  63 +
  64 +found:
  65 +       if (!of_property_read_u32(np, "mac-address-increment", &mac_inc)) {
  66 +               /* Convert to a contiguous value */
  67 +               mac_val = (addr[3] << 16) + (addr[4] << 8) + addr[5];
  68 +               mac_val += mac_inc;
  69 +
  70 +               /* Apply the incremented value handling overflow case */
  71 +               addr[3] = (mac_val >> 16) & 0xff;
  72 +               addr[4] = (mac_val >> 8) & 0xff;
  73 +               addr[5] = (mac_val >> 0) & 0xff;
  74 +       }
  75
  76 -       return of_get_mac_addr_nvmem(np, addr);
  77 +       return ret;
  78  }
  79  EXPORT_SYMBOL(of_get_mac_address);
  80