i2c: Replace list-based mechanism for handling auto-detected clients

So far a list is used to track auto-detected clients per driver.
The same functionality can be achieved much simpler by flagging
auto-detected clients.

Two notes regarding the usage of driver_for_each_device:
In our case it can't fail, however the function is annotated __must_check.
So a little workaround is needed to avoid a compiler warning.
Then we may remove nodes from the list over which we iterate.
This is safe, see the explanation at the beginning of lib/klist.c.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
[wsa: fixed description of the new flag]
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 7c810893bfa332721d242f6c4a83f6217f22a6fc..42c62839de0caf5e602d71f96d8cdfdb2f6021fc 100644 (file)
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1696,23 +1696,6 @@ int i2c_add_numbered_adapter(struct i2c_adapter *adap)
 }
 EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);
 
-static void i2c_do_del_adapter(struct i2c_driver *driver,
-                             struct i2c_adapter *adapter)
-{
-       struct i2c_client *client, *_n;
-
-       /* Remove the devices we created ourselves as the result of hardware
-        * probing (using a driver's detect method) */
-       list_for_each_entry_safe(client, _n, &driver->clients, detected) {
-               if (client->adapter == adapter) {
-                       dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
-                               client->name, client->addr);
-                       list_del(&client->detected);
-                       i2c_unregister_device(client);
-               }
-       }
-}
-
 static int __unregister_client(struct device *dev, void *dummy)
 {
        struct i2c_client *client = i2c_verify_client(dev);
@@ -1728,12 +1711,6 @@ static int __unregister_dummy(struct device *dev, void *dummy)
        return 0;
 }
 
-static int __process_removed_adapter(struct device_driver *d, void *data)
-{
-       i2c_do_del_adapter(to_i2c_driver(d), data);
-       return 0;
-}
-
 /**
  * i2c_del_adapter - unregister I2C adapter
  * @adap: the adapter being unregistered
@@ -1757,11 +1734,6 @@ void i2c_del_adapter(struct i2c_adapter *adap)
        }
 
        i2c_acpi_remove_space_handler(adap);
-       /* Tell drivers about this removal */
-       mutex_lock(&core_lock);
-       bus_for_each_drv(&i2c_bus_type, NULL, adap,
-                              __process_removed_adapter);
-       mutex_unlock(&core_lock);
 
        /* Remove devices instantiated from sysfs */
        mutex_lock_nested(&adap->userspace_clients_lock,
@@ -1780,8 +1752,10 @@ void i2c_del_adapter(struct i2c_adapter *adap)
         * we can't remove the dummy devices during the first pass: they
         * could have been instantiated by real devices wishing to clean
         * them up properly, so we give them a chance to do that first. */
+       mutex_lock(&core_lock);
        device_for_each_child(&adap->dev, NULL, __unregister_client);
        device_for_each_child(&adap->dev, NULL, __unregister_dummy);
+       mutex_unlock(&core_lock);
 
        /* device name is gone after device_unregister */
        dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);
@@ -2001,7 +1975,6 @@ int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
        /* add the driver to the list of i2c drivers in the driver core */
        driver->driver.owner = owner;
        driver->driver.bus = &i2c_bus_type;
-       INIT_LIST_HEAD(&driver->clients);
 
        /* When registration returns, the driver core
         * will have called probe() for all matching-but-unbound devices.
@@ -2019,10 +1992,13 @@ int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
 }
 EXPORT_SYMBOL(i2c_register_driver);
 
-static int __process_removed_driver(struct device *dev, void *data)
+static int __i2c_unregister_detected_client(struct device *dev, void *argp)
 {
-       if (dev->type == &i2c_adapter_type)
-               i2c_do_del_adapter(data, to_i2c_adapter(dev));
+       struct i2c_client *client = i2c_verify_client(dev);
+
+       if (client && client->flags & I2C_CLIENT_AUTO)
+               i2c_unregister_device(client);
+
        return 0;
 }
 
@@ -2033,7 +2009,12 @@ static int __process_removed_driver(struct device *dev, void *data)
  */
 void i2c_del_driver(struct i2c_driver *driver)
 {
-       i2c_for_each_dev(driver, __process_removed_driver);
+       mutex_lock(&core_lock);
+       /* Satisfy __must_check, function can't fail */
+       if (driver_for_each_device(&driver->driver, NULL, NULL,
+                                  __i2c_unregister_detected_client)) {
+       }
+       mutex_unlock(&core_lock);
 
        driver_unregister(&driver->driver);
        pr_debug("driver [%s] unregistered\n", driver->driver.name);
@@ -2460,6 +2441,7 @@ static int i2c_detect_address(struct i2c_client *temp_client,
        /* Finally call the custom detection function */
        memset(&info, 0, sizeof(struct i2c_board_info));
        info.addr = addr;
+       info.flags = I2C_CLIENT_AUTO;
        err = driver->detect(temp_client, &info);
        if (err) {
                /* -ENODEV is returned if the detection fails. We catch it
@@ -2486,9 +2468,7 @@ static int i2c_detect_address(struct i2c_client *temp_client,
                dev_dbg(&adapter->dev, "Creating %s at 0x%02x\n",
                        info.type, info.addr);
                client = i2c_new_client_device(adapter, &info);
-               if (!IS_ERR(client))
-                       list_add_tail(&client->detected, &driver->clients);
-               else
+               if (IS_ERR(client))
                        dev_err(&adapter->dev, "Failed creating %s at 0x%02x\n",
                                info.type, info.addr);
        }

diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 388ce71a29a979310f065a720534fccd2c0ad2e2..072a62244e14a8b412b49386703d532834c569a2 100644 (file)
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -244,7 +244,6 @@ enum i2c_driver_flags {
  * @id_table: List of I2C devices supported by this driver
  * @detect: Callback for device detection
  * @address_list: The I2C addresses to probe (for detect)
- * @clients: List of detected clients we created (for i2c-core use only)
  * @flags: A bitmask of flags defined in &enum i2c_driver_flags
  *
  * The driver.owner field should be set to the module owner of this driver.
@@ -299,7 +298,6 @@ struct i2c_driver {
        /* Device detection callback for automatic device creation */
        int (*detect)(struct i2c_client *client, struct i2c_board_info *info);
        const unsigned short *address_list;
-       struct list_head clients;
 
        u32 flags;
 };
@@ -334,6 +332,7 @@ struct i2c_client {
 #define I2C_CLIENT_SLAVE       0x20    /* we are the slave */
 #define I2C_CLIENT_HOST_NOTIFY 0x40    /* We want to use I2C host notify */
 #define I2C_CLIENT_WAKE                0x80    /* for board_info; true iff can wake */
+#define I2C_CLIENT_AUTO                0x100   /* client was auto-detected */
 #define I2C_CLIENT_SCCB                0x9000  /* Use Omnivision SCCB protocol */
                                        /* Must match I2C_M_STOP|IGNORE_NAK */