i2c-dev: Unbound new-style i2c clients aren't busy

Let i2c-dev deal properly with new-style i2c clients. Instead of
considering them always busy, it needs to check wether a driver is
bound to them or not.

This is still not completely correct, as the client could become
busy later, but the same problem already existed before new-style
clients were introduced. We'll want to fix it someday.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>

diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index 7360f9c37256c69cf9f9dd0191638a40afe62d6d..c21ae20ae362b059a2c347238f0e063616e0411e 100644 (file)
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -182,6 +182,29 @@ static ssize_t i2cdev_write (struct file *file, const char __user *buf, size_t c
        return ret;
 }
 
+/* This address checking function differs from the one in i2c-core
+   in that it considers an address with a registered device, but no
+   bounded driver, as NOT busy. */
+static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
+{
+       struct list_head *item;
+       struct i2c_client *client;
+       int res = 0;
+
+       mutex_lock(&adapter->clist_lock);
+       list_for_each(item, &adapter->clients) {
+               client = list_entry(item, struct i2c_client, list);
+               if (client->addr == addr) {
+                       if (client->driver)
+                               res = -EBUSY;
+                       break;
+               }
+       }
+       mutex_unlock(&adapter->clist_lock);
+
+       return res;
+}
+
 static int i2cdev_ioctl(struct inode *inode, struct file *file,
                unsigned int cmd, unsigned long arg)
 {
@@ -213,8 +236,9 @@ static int i2cdev_ioctl(struct inode *inode, struct file *file,
                if ((arg > 0x3ff) ||
                    (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
                        return -EINVAL;
-               if ((cmd == I2C_SLAVE) && i2c_check_addr(client->adapter,arg))
+               if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
                        return -EBUSY;
+               /* REVISIT: address could become busy later */
                client->addr = arg;
                return 0;
        case I2C_TENBIT: