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Date: Tue, 14 Aug 2018 15:37:57 -0700
From: Brian Norris <computersforpeace@...il.com>
To: Rob Herring <robh+dt@...nel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J. Wysocki" <rafael@...nel.org>
Cc: Andrew Lunn <andrew@...n.ch>,
Florian Fainelli <f.fainelli@...il.com>,
Dmitry Torokhov <dmitry.torokhov@...il.com>,
Guenter Roeck <linux@...ck-us.net>, netdev@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
Julius Werner <jwerner@...omium.org>,
Stephen Boyd <swboyd@...omium.org>,
Brian Norris <briannorris@...omium.org>
Subject: [RFC PATCH v1 2/3] device property: Support complex MAC address lookup
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@...omium.org>
---
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
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