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From 844c273286f328acf0dab5fbd5d864366b4904dc Mon Sep 17 00:00:00 2001
From: Ansuel Smith <ansuelsmth@gmail.com>
Date: Tue, 30 Mar 2021 18:21:14 +0200
Subject: [PATCH] of_net: add mac-address-increment support
Lots of embedded devices use the mac-address of other interface
extracted from nvmem cells and increments it by one or two. Add two
bindings to integrate this and directly use the right mac-address for
the interface. Some example are some routers that use the gmac
mac-address stored in the art partition and increments it by one for the
wifi. mac-address-increment-byte bindings is used to tell what byte of
the mac-address has to be increased (if not defined the last byte is
increased) and mac-address-increment tells how much the byte decided
early has to be increased.
Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
---
net/core/of_net.c | 43 +++++++++++++++++++++++++++++++++++++++----
1 file changed, 39 insertions(+), 4 deletions(-)
--- a/net/core/of_net.c
+++ b/net/core/of_net.c
@@ -119,27 +119,62 @@ static int of_get_mac_addr_nvmem(struct
* this case, the real MAC is in 'local-mac-address', and 'mac-address' exists
* but is all zeros.
*
+ * DT can tell the system to increment the mac-address after is extracted by
+ * using:
+ * - mac-address-increment-byte to decide what byte to increase
+ * (if not defined is increased the last byte)
+ * - mac-address-increment to decide how much to increase. The value WILL
+ * overflow to other bytes if the increment is over 255 or the total
+ * increment will exceed 255 of the current byte.
+ * (example 00:01:02:03:04:ff + 1 == 00:01:02:03:05:00)
+ * (example 00:01:02:03:04:fe + 5 == 00:01:02:03:05:03)
+ *
* Return: 0 on success and errno in case of error.
*/
int of_get_mac_address(struct device_node *np, u8 *addr)
{
+ u32 inc_idx, mac_inc, mac_val;
int ret;
+ /* Check first if the increment byte is present and valid.
+ * If not set assume to increment the last byte if found.
+ */
+ if (of_property_read_u32(np, "mac-address-increment-byte", &inc_idx))
+ inc_idx = 5;
+ if (inc_idx < 3 || inc_idx > 5)
+ return -EINVAL;
+
if (!np)
return -ENODEV;
ret = of_get_mac_addr(np, "mac-address", addr);
if (!ret)
- return 0;
+ goto found;
ret = of_get_mac_addr(np, "local-mac-address", addr);
if (!ret)
- return 0;
+ goto found;
ret = of_get_mac_addr(np, "address", addr);
if (!ret)
- return 0;
+ goto found;
+
+ ret = of_get_mac_addr_nvmem(np, addr);
+ if (ret)
+ return ret;
+
+found:
+ if (!of_property_read_u32(np, "mac-address-increment", &mac_inc)) {
+ /* Convert to a contiguous value */
+ mac_val = (addr[3] << 16) + (addr[4] << 8) + addr[5];
+ mac_val += mac_inc << 8 * (5-inc_idx);
+
+ /* Apply the incremented value handling overflow case */
+ addr[3] = (mac_val >> 16) & 0xff;
+ addr[4] = (mac_val >> 8) & 0xff;
+ addr[5] = (mac_val >> 0) & 0xff;
+ }
- return of_get_mac_addr_nvmem(np, addr);
+ return ret;
}
EXPORT_SYMBOL(of_get_mac_address);
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