Some firmwares include data tables that can be used to derive a MAC address for devices on the system, but those firmwares don't directly stash the MAC address in a device property. Support having other drivers register lookup functions, where the device property contains "<format>:<key>" strings; a lookup driver can register support for handling "<format>", and "<key>" can be used by the format parser to identify which MAC address is being requested. This is particularly useful for the Google Vital Product Data (VPD) format [1], which holds various product-specific key/value pairs, often stashed in the boot flash. [1] Ref: https://chromium.googlesource.com/chromiumos/platform/vpd/+/master/README.md Signed-off-by: Brian Norris <briannorris@xxxxxxxxxxxx> --- drivers/base/property.c | 83 +++++++++++++++++++++++++++++++++++++++- include/linux/property.h | 23 +++++++++++ 2 files changed, 104 insertions(+), 2 deletions(-) diff --git a/drivers/base/property.c b/drivers/base/property.c index 240ab5230ff6..fae3390fc56c 100644 --- a/drivers/base/property.c +++ b/drivers/base/property.c @@ -10,6 +10,7 @@ #include <linux/acpi.h> #include <linux/export.h> #include <linux/kernel.h> +#include <linux/mutex.h> #include <linux/of.h> #include <linux/of_address.h> #include <linux/of_graph.h> @@ -1264,6 +1265,78 @@ static void *fwnode_get_mac_addr(struct fwnode_handle *fwnode, return NULL; } +static LIST_HEAD(mac_addr_providers); +static DEFINE_MUTEX(mac_addr_providers_mutex); + +void device_register_mac_addr_provider(struct device_mac_addr_provider *prov) +{ + mutex_lock(&mac_addr_providers_mutex); + list_add(&prov->entry, &mac_addr_providers); + mutex_unlock(&mac_addr_providers_mutex); +} +EXPORT_SYMBOL(device_register_mac_addr_provider); + +void device_unregister_mac_addr_provider(struct device_mac_addr_provider *prov) +{ + struct device_mac_addr_provider *p; + + mutex_lock(&mac_addr_providers_mutex); + list_for_each_entry(p, &mac_addr_providers, entry) { + if (p == prov) { + list_del(&p->entry); + goto out; + } + } + +out: + mutex_unlock(&mac_addr_providers_mutex); +} +EXPORT_SYMBOL(device_unregister_mac_addr_provider); + +static void *fwnode_lookup_mac_addr(struct fwnode_handle *fwnode, + char *addr, int alen) +{ + struct device_mac_addr_provider *prov; + const char *prop, *sep; + u8 mac[ETH_ALEN]; + int ret; + + ret = fwnode_property_read_string(fwnode, "mac-address-lookup", &prop); + if (ret) + return NULL; + + sep = strchr(prop, ':'); + if (!sep) + return NULL; + + if (alen != ETH_ALEN) + return NULL; + + mutex_lock(&mac_addr_providers_mutex); + list_for_each_entry(prov, &mac_addr_providers, entry) { + if (strncmp(prov->prefix, prop, strlen(prov->prefix))) + continue; + + if (prop + strlen(prov->prefix) != sep) + continue; + + ret = prov->lookup(sep + 1, mac); + if (ret) + continue; + + if (!is_valid_ether_addr(mac)) + continue; + + ether_addr_copy(addr, mac); + + mutex_unlock(&mac_addr_providers_mutex); + return addr; + } + mutex_unlock(&mac_addr_providers_mutex); + + return NULL; +} + /** * fwnode_get_mac_address - Get the MAC from the firmware node * @fwnode: Pointer to the firmware node @@ -1274,7 +1347,9 @@ static void *fwnode_get_mac_addr(struct fwnode_handle *fwnode, * checked first, because that is supposed to contain to "most recent" MAC * address. If that isn't set, then 'local-mac-address' is checked next, * because that is the default address. If that isn't set, then the obsolete - * 'address' is checked, just in case we're using an old device tree. + * 'address' is checked, just in case we're using an old device tree. And + * finally, we check for a method of indirect MAC address lookup, via + * 'mac-address-lookup'. * * Note that the 'address' property is supposed to contain a virtual address of * the register set, but some DTS files have redefined that property to be the @@ -1299,7 +1374,11 @@ void *fwnode_get_mac_address(struct fwnode_handle *fwnode, char *addr, int alen) if (res) return res; - return fwnode_get_mac_addr(fwnode, "address", addr, alen); + res = fwnode_get_mac_addr(fwnode, "address", addr, alen); + if (res) + return res; + + return fwnode_lookup_mac_addr(fwnode, addr, alen); } EXPORT_SYMBOL(fwnode_get_mac_address); diff --git a/include/linux/property.h b/include/linux/property.h index ac8a1ebc4c1b..aca5dbb51e19 100644 --- a/include/linux/property.h +++ b/include/linux/property.h @@ -14,6 +14,7 @@ #define _LINUX_PROPERTY_H_ #include <linux/fwnode.h> +#include <linux/list.h> #include <linux/types.h> struct device; @@ -285,6 +286,28 @@ const void *device_get_match_data(struct device *dev); int device_get_phy_mode(struct device *dev); +/** + * struct device_mac_addr_provider - MAC address provider + * + * Provide methods by which the rest of the kernel can retrieve MAC addresses, + * e.g., from a firmware table. + * + * @entry: list head, for keeping track of all providers + * @prefix: string which uniquely identifies the provider + * @lookup: Look up a MAC address by key. The provider may associate this @key + * with a stored MAC address; if a match is found, the provider copies the + * associated MAC address to @mac. If not found, a non-zero error code is + * returned. + */ +struct device_mac_addr_provider { + struct list_head entry; + const char *prefix; + int (*lookup)(const char *key, u8 *mac); +}; + +void device_register_mac_addr_provider(struct device_mac_addr_provider *prov); +void device_unregister_mac_addr_provider(struct device_mac_addr_provider *prov); + void *device_get_mac_address(struct device *dev, char *addr, int alen); int fwnode_get_phy_mode(struct fwnode_handle *fwnode); -- 2.18.0.865.gffc8e1a3cd6-goog
