i2c: Add support for device alias names

Based on earlier work by Jon Smirl and Jochen Friedrich.

This patch allows new-style i2c chip drivers to have alias names using
the official kernel aliasing system and MODULE_DEVICE_TABLE(). At this
point, the old i2c driver binding scheme (driver_name/type) is still
supported.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Jochen Friedrich <jochen@scram.de>
Cc: Jon Smirl <jonsmirl@gmail.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>

1 files changed, 42 insertions, 9 deletions

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 6c7fa8d53c0e..26384daccb96 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -48,6 +48,17 @@ static DEFINE_IDR(i2c_adapter_idr);
 
 /* ------------------------------------------------------------------------- */
 
+static const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
+                                                const struct i2c_client *client)
+{
+        while (id->name[0]) {
+                if (strcmp(client->name, id->name) == 0)
+                        return id;
+                id++;
+        }
+        return NULL;
+}
+
 static int i2c_device_match(struct device *dev, struct device_driver *drv)
 {
         struct i2c_client       *client = to_i2c_client(dev);
@@ -59,6 +70,10 @@ static int i2c_device_match(struct device *dev, struct device_driver *drv)
         if (!is_newstyle_driver(driver))
                 return 0;
 
+        /* match on an id table if there is one */
+        if (driver->id_table)
+                return i2c_match_id(driver->id_table, client) != NULL;
+
         /* new style drivers use the same kind of driver matching policy
          * as platform devices or SPI:  compare device and driver IDs.
          */
@@ -73,11 +88,17 @@ static int i2c_device_uevent(struct device *dev, struct kobj_uevent_env *env)
         struct i2c_client       *client = to_i2c_client(dev);
 
         /* by definition, legacy drivers can't hotplug */
-        if (dev->driver || !client->driver_name)
+        if (dev->driver)
                 return 0;
 
-        if (add_uevent_var(env, "MODALIAS=%s", client->driver_name))
-                return -ENOMEM;
+        if (client->driver_name[0]) {
+                if (add_uevent_var(env, "MODALIAS=%s", client->driver_name))
+                        return -ENOMEM;
+        } else {
+                if (add_uevent_var(env, "MODALIAS=%s%s",
+                                   I2C_MODULE_PREFIX, client->name))
+                        return -ENOMEM;
+        }
         dev_dbg(dev, "uevent\n");
         return 0;
 }
@@ -90,13 +111,19 @@ static int i2c_device_probe(struct device *dev)
 {
         struct i2c_client       *client = to_i2c_client(dev);
         struct i2c_driver       *driver = to_i2c_driver(dev->driver);
+        const struct i2c_device_id *id;
         int status;
 
         if (!driver->probe)
                 return -ENODEV;
         client->driver = driver;
         dev_dbg(dev, "probe\n");
-        status = driver->probe(client);
+
+        if (driver->id_table)
+                id = i2c_match_id(driver->id_table, client);
+        else
+                id = NULL;
+        status = driver->probe(client, id);
         if (status)
                 client->driver = NULL;
         return status;
@@ -179,9 +206,9 @@ static ssize_t show_client_name(struct device *dev, struct device_attribute *att
 static ssize_t show_modalias(struct device *dev, struct device_attribute *attr, char *buf)
 {
         struct i2c_client *client = to_i2c_client(dev);
-        return client->driver_name
+        return client->driver_name[0]
                 ? sprintf(buf, "%s\n", client->driver_name)
-                : 0;
+                : sprintf(buf, "%s%s\n", I2C_MODULE_PREFIX, client->name);
 }
 
 static struct device_attribute i2c_dev_attrs[] = {
@@ -300,15 +327,21 @@ void i2c_unregister_device(struct i2c_client *client)
 EXPORT_SYMBOL_GPL(i2c_unregister_device);
 
 
-static int dummy_nop(struct i2c_client *client)
+static int dummy_probe(struct i2c_client *client,
+                       const struct i2c_device_id *id)
+{
+        return 0;
+}
+
+static int dummy_remove(struct i2c_client *client)
 {
         return 0;
 }
 
 static struct i2c_driver dummy_driver = {
         .driver.name    = "dummy",
-        .probe          = dummy_nop,
-        .remove         = dummy_nop,
+        .probe          = dummy_probe,
+        .remove         = dummy_remove,
 };
 
 /**