Re: [PATCH] of_net: add mtd-mac-address support to of_get_mac_address()

Heiner Kallweit
2019-04-17T05:00:45Z

On 16.04.2019 22:05, Petr Štetiar wrote:
> From: John Crispin <john@phrozen.org>
>
> Many embedded devices have information such as MAC addresses stored
> inside MTD devices. This patch allows us to add a property inside a node
> describing a network interface. The new property points at a MTD
> partition with an offset where the MAC address can be found.
>
> This patch has originated in OpenWrt some time ago, so in order to
> consider usefulness of this patch, here are some real-world numbers
> which hopefully speak for themselves:
>
> * mtd-mac-address used 497 times in 357 device tree files
> * mtd-mac-address-increment used 74 times in 58 device tree files
> * mtd-mac-address-increment-byte used 1 time in 1 device tree file
>
> Signed-off-by: John Crispin <john@phrozen.org>
> Signed-off-by: Felix Fietkau <nbd@nbd.name>
> [cleanup of the patch for upstream submission]
> Signed-off-by: Petr Štetiar <ynezz@true.cz>
> ---
> Documentation/devicetree/bindings/net/ethernet.txt | 5 ++
> drivers/of/of_net.c | 82 +++++++++++++++++++++-
> 2 files changed, 86 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/devicetree/bindings/net/ethernet.txt b/Documentation/devicetree/bindings/net/ethernet.txt
> index cfc376b..8a7891e 100644
> --- a/Documentation/devicetree/bindings/net/ethernet.txt
> +++ b/Documentation/devicetree/bindings/net/ethernet.txt
> @@ -10,6 +10,11 @@ Documentation/devicetree/bindings/phy/phy-bindings.txt.
> the boot program; should be used in cases where the MAC address assigned to
> the device by the boot program is different from the "local-mac-address"
> property;
> +- mtd-mac-address: specify a MTD partition + offset containing array of 6 bytes
> +- mtd-mac-address-increment: specify number by which we should increment the
> + MAC address stored in the MTD partition
> +- mtd-mac-address-increment-byte: specify octet/byte(0-5) in the MAC address,
> + where we should increment the value, defaults to octet 5 (the last one)
> - nvmem-cells: phandle, reference to an nvmem node for the MAC address;
> - nvmem-cell-names: string, should be "mac-address" if nvmem is to be used;
> - max-speed: number, specifies maximum speed in Mbit/s supported by the device;
> diff --git a/drivers/of/of_net.c b/drivers/of/of_net.c
> index 810ab0f..01b24d6 100644
> --- a/drivers/of/of_net.c
> +++ b/drivers/of/of_net.c
> @@ -11,6 +11,7 @@
> #include <linux/of_net.h>
> #include <linux/phy.h>
> #include <linux/export.h>
> +#include <linux/mtd/mtd.h>
>
> /**
> * of_get_phy_mode - Get phy mode for given device_node
> @@ -39,7 +40,7 @@ int of_get_phy_mode(struct device_node *np)
> }
> 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);
>
> @@ -48,6 +49,78 @@ static const void *of_get_mac_addr(struct device_node *np, const char *name)
> return NULL;
> }
>
> +static const void *of_get_mac_address_mtd(struct device_node *np)
> +{
> +#ifdef CONFIG_MTD
> + void *addr;
> + size_t retlen;
> + int size, ret;
> + u8 mac[ETH_ALEN];
> + phandle phandle;
> + const char *part;
> + const __be32 *list;
> + struct mtd_info *mtd;
> + struct property *prop;
> + u32 mac_inc = 0;
> + u32 inc_idx = ETH_ALEN-1;
> + struct device_node *mtd_np = NULL;
> +
> + list = of_get_property(np, "mtd-mac-address", &size);
> + if (!list || (size != (2 * sizeof(*list))))
> + return NULL;
> +
> + phandle = be32_to_cpup(list++);
> + if (phandle)
> + mtd_np = of_find_node_by_phandle(phandle);
> +
> + if (!mtd_np)
> + return NULL;
> +
> + part = of_get_property(mtd_np, "label", NULL);
> + if (!part)
> + part = mtd_np->name;
> +
> + mtd = get_mtd_device_nm(part);
> + if (IS_ERR(mtd))
> + return NULL;
> +
> + ret = mtd_read(mtd, be32_to_cpup(list), ETH_ALEN, &retlen, mac);

ret doesn't seem to be checked. And checking retlen wouldn't be bad too.

> + put_mtd_device(mtd);
> +
> + of_property_read_u32(np, "mtd-mac-address-increment-byte", &inc_idx);
> + if (inc_idx > ETH_ALEN-1)
> + return NULL;
> +
> + if (!of_property_read_u32(np, "mtd-mac-address-increment", &mac_inc))
> + mac[inc_idx] += mac_inc;
> +
> + if (!is_valid_ether_addr(mac))
> + return NULL;
> +
> + addr = of_get_mac_addr(np, "mac-address");
> + if (addr) {
> + memcpy(addr, mac, ETH_ALEN);
> + return addr;
> + }
> +
> + prop = kzalloc(sizeof(*prop), GFP_KERNEL);
> + if (!prop)
> + return NULL;
> +
> + prop->name = "mac-address";
> + prop->length = ETH_ALEN;
> + prop->value = kmemdup(mac, ETH_ALEN, GFP_KERNEL);
> + if (!prop->value || of_add_property(np, prop))
> + goto free;
> +
> + return prop->value;
> +free:
> + kfree(prop->value);
> + kfree(prop);
> +#endif
> + return NULL;
> +}
> +
> /**
> * Search the device tree for the best MAC address to use. 'mac-address' is
> * checked first, because that is supposed to contain to "most recent" MAC
> @@ -65,11 +138,18 @@ static const void *of_get_mac_addr(struct device_node *np, const char *name)
> * addresses. Some older U-Boots only initialized 'local-mac-address'. In
> * this case, the real MAC is in 'local-mac-address', and 'mac-address' exists
> * but is all zeros.
> + *
> + * If a mtd-mac-address property exists, try to fetch the MAC address from the
> + * specified MTD device, and store it as a 'mac-address' property.
> */
> const void *of_get_mac_address(struct device_node *np)
> {
> const void *addr;
>
> + addr = of_get_mac_address_mtd(np);
> + if (addr)
> + return addr;
> +
> addr = of_get_mac_addr(np, "mac-address");
> if (addr)
> return addr;
>