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Subject[PATCH v3 3/4] of_net: add mac-address-increment support
Date
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>
---
drivers/of/of_net.c | 57 ++++++++++++++++++++++++++++++++++-----------
1 file changed, 44 insertions(+), 13 deletions(-)

diff --git a/drivers/of/of_net.c b/drivers/of/of_net.c
index 6e411821583e..bafbc833e659 100644
--- a/drivers/of/of_net.c
+++ b/drivers/of/of_net.c
@@ -45,7 +45,7 @@ int of_get_phy_mode(struct device_node *np, phy_interface_t *interface)
}
EXPORT_SYMBOL_GPL(of_get_phy_mode);

-static const void *of_get_mac_addr(struct device_node *np, const char *name)
+static void *of_get_mac_addr(struct device_node *np, const char *name)
{
struct property *pp = of_find_property(np, name, NULL);

@@ -54,26 +54,31 @@ static const void *of_get_mac_addr(struct device_node *np, const char *name)
return NULL;
}

-static const void *of_get_mac_addr_nvmem(struct device_node *np)
+static void *of_get_mac_addr_nvmem(struct device_node *np, int *err)
{
int ret;
- const void *mac;
+ void *mac;
u8 nvmem_mac[ETH_ALEN];
struct platform_device *pdev = of_find_device_by_node(np);

- if (!pdev)
- return ERR_PTR(-ENODEV);
+ if (!pdev) {
+ *err = -ENODEV;
+ return NULL;
+ }

ret = nvmem_get_mac_address(&pdev->dev, &nvmem_mac);
if (ret) {
put_device(&pdev->dev);
- return ERR_PTR(ret);
+ *err = ret;
+ return NULL;
}

mac = devm_kmemdup(&pdev->dev, nvmem_mac, ETH_ALEN, GFP_KERNEL);
put_device(&pdev->dev);
- if (!mac)
- return ERR_PTR(-ENOMEM);
+ if (!mac) {
+ *err = -ENOMEM;
+ return NULL;
+ }

return mac;
}
@@ -98,24 +103,50 @@ static const void *of_get_mac_addr_nvmem(struct device_node *np)
* 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
+ * not overflow to other bytes if the increment is over 255.
+ * (example 00:01:02:03:04:ff + 1 == 00:01:02:03:04:00)
+ *
* Return: Will be a valid pointer on success and ERR_PTR in case of error.
*/
const void *of_get_mac_address(struct device_node *np)
{
- const void *addr;
+ u32 inc_idx, mac_inc;
+ int ret = 0;
+ u8 *addr;
+
+ /* 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 ERR_PTR(-EINVAL);

addr = of_get_mac_addr(np, "mac-address");
if (addr)
- return addr;
+ goto found;

addr = of_get_mac_addr(np, "local-mac-address");
if (addr)
- return addr;
+ goto found;

addr = of_get_mac_addr(np, "address");
if (addr)
- return addr;
+ goto found;
+
+ addr = of_get_mac_addr_nvmem(np, &ret);
+ if (ret)
+ return ERR_PTR(ret);
+
+found:
+ if (!of_property_read_u32(np, "mac-address-increment", &mac_inc))
+ addr[inc_idx] += mac_inc;

- return of_get_mac_addr_nvmem(np);
+ return addr;
}
EXPORT_SYMBOL(of_get_mac_address);
--
2.27.0
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