i2c-dev: Split i2cdev_ioctl

Split the handling of the I2C_RDWR and I2C_SMBUS ioctls to their own
functions. This limits the stack usage, saves one level of indentation
and makes the code more readable.
Signed-off-by: Jean Delvare <khali@linux-fr.org>

drivers/i2c/i2c-dev.c

@@ -200,59 +200,14 @@ static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
 	return device_for_each_child(&adapter->dev, &addr, i2cdev_check);
 }
 
-static int i2cdev_ioctl(struct inode *inode, struct file *file,
-		unsigned int cmd, unsigned long arg)
+static noinline int i2cdev_ioctl_rdrw(struct i2c_client *client,
+		unsigned long arg)
 {
-	struct i2c_client *client = (struct i2c_client *)file->private_data;
 	struct i2c_rdwr_ioctl_data rdwr_arg;
-	struct i2c_smbus_ioctl_data data_arg;
-	union i2c_smbus_data temp;
 	struct i2c_msg *rdwr_pa;
 	u8 __user **data_ptrs;
-	int i,datasize,res;
-	unsigned long funcs;
-
-	dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
-		cmd, arg);
+	int i, res;
 
-	switch ( cmd ) {
-	case I2C_SLAVE:
-	case I2C_SLAVE_FORCE:
-		/* NOTE:  devices set up to work with "new style" drivers
-		 * can't use I2C_SLAVE, even when the device node is not
-		 * bound to a driver.  Only I2C_SLAVE_FORCE will work.
-		 *
-		 * Setting the PEC flag here won't affect kernel drivers,
-		 * which will be using the i2c_client node registered with
-		 * the driver model core.  Likewise, when that client has
-		 * the PEC flag already set, the i2c-dev driver won't see
-		 * (or use) this setting.
-		 */
-		if ((arg > 0x3ff) ||
-		    (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
-			return -EINVAL;
-		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:
-		if (arg)
-			client->flags |= I2C_M_TEN;
-		else
-			client->flags &= ~I2C_M_TEN;
-		return 0;
-	case I2C_PEC:
-		if (arg)
-			client->flags |= I2C_CLIENT_PEC;
-		else
-			client->flags &= ~I2C_CLIENT_PEC;
-		return 0;
-	case I2C_FUNCS:
-		funcs = i2c_get_functionality(client->adapter);
-		return put_user(funcs, (unsigned long __user *)arg);
-
-	case I2C_RDWR:
 	if (copy_from_user(&rdwr_arg,
 			   (struct i2c_rdwr_ioctl_data __user *)arg,
 			   sizeof(rdwr_arg)))
@@ -266,8 +221,8 @@ static int i2cdev_ioctl(struct inode *inode, struct file *file,
 	rdwr_pa = (struct i2c_msg *)
 		kmalloc(rdwr_arg.nmsgs * sizeof(struct i2c_msg),
 		GFP_KERNEL);
-
-		if (rdwr_pa == NULL) return -ENOMEM;
+	if (!rdwr_pa)
+		return -ENOMEM;
 
 	if (copy_from_user(rdwr_pa, rdwr_arg.msgs,
 			   rdwr_arg.nmsgs * sizeof(struct i2c_msg))) {
@@ -282,7 +237,7 @@ static int i2cdev_ioctl(struct inode *inode, struct file *file,
 	}
 
 	res = 0;
-		for( i=0; i<rdwr_arg.nmsgs; i++ ) {
+	for (i = 0; i < rdwr_arg.nmsgs; i++) {
 		/* Limit the size of the message to a sane amount;
 		 * and don't let length change either. */
 		if ((rdwr_pa[i].len > 8192) ||
@@ -292,12 +247,11 @@ static int i2cdev_ioctl(struct inode *inode, struct file *file,
 		}
 		data_ptrs[i] = (u8 __user *)rdwr_pa[i].buf;
 		rdwr_pa[i].buf = kmalloc(rdwr_pa[i].len, GFP_KERNEL);
-			if(rdwr_pa[i].buf == NULL) {
+		if (rdwr_pa[i].buf == NULL) {
 			res = -ENOMEM;
 			break;
 		}
-			if(copy_from_user(rdwr_pa[i].buf,
-				data_ptrs[i],
+		if (copy_from_user(rdwr_pa[i].buf, data_ptrs[i],
 				   rdwr_pa[i].len)) {
 				++i; /* Needs to be kfreed too */
 				res = -EFAULT;
@@ -313,25 +267,27 @@ static int i2cdev_ioctl(struct inode *inode, struct file *file,
 		return res;
 	}
 
-		res = i2c_transfer(client->adapter,
-			rdwr_pa,
-			rdwr_arg.nmsgs);
-		while(i-- > 0) {
-			if( res>=0 && (rdwr_pa[i].flags & I2C_M_RD)) {
-				if(copy_to_user(
-					data_ptrs[i],
-					rdwr_pa[i].buf,
-					rdwr_pa[i].len)) {
+	res = i2c_transfer(client->adapter, rdwr_pa, rdwr_arg.nmsgs);
+	while (i-- > 0) {
+		if (res >= 0 && (rdwr_pa[i].flags & I2C_M_RD)) {
+			if (copy_to_user(data_ptrs[i], rdwr_pa[i].buf,
+					 rdwr_pa[i].len))
 				res = -EFAULT;
 		}
-			}
 		kfree(rdwr_pa[i].buf);
 	}
 	kfree(data_ptrs);
 	kfree(rdwr_pa);
 	return res;
+}
+
+static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
+		unsigned long arg)
+{
+	struct i2c_smbus_ioctl_data data_arg;
+	union i2c_smbus_data temp;
+	int datasize, res;
 
-	case I2C_SMBUS:
 	if (copy_from_user(&data_arg,
 			   (struct i2c_smbus_ioctl_data __user *) arg,
 			   sizeof(struct i2c_smbus_ioctl_data)))
@@ -367,10 +323,8 @@ static int i2cdev_ioctl(struct inode *inode, struct file *file,
 	    (data_arg.read_write == I2C_SMBUS_WRITE)))
 		/* These are special: we do not use data */
 		return i2c_smbus_xfer(client->adapter, client->addr,
-					      client->flags,
-					      data_arg.read_write,
-					      data_arg.command,
-					      data_arg.size, NULL);
+				      client->flags, data_arg.read_write,
+				      data_arg.command, data_arg.size, NULL);
 
 	if (data_arg.data == NULL) {
 		dev_dbg(&client->adapter->dev,
@@ -401,16 +355,69 @@ static int i2cdev_ioctl(struct inode *inode, struct file *file,
 		if (data_arg.read_write == I2C_SMBUS_READ)
 			temp.block[0] = I2C_SMBUS_BLOCK_MAX;
 	}
-		res = i2c_smbus_xfer(client->adapter,client->addr,client->flags,
-		      data_arg.read_write,
-		      data_arg.command,data_arg.size,&temp);
-		if (! res && ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
+	res = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
+	      data_arg.read_write, data_arg.command, data_arg.size, &temp);
+	if (!res && ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
 		     (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 		     (data_arg.read_write == I2C_SMBUS_READ))) {
 		if (copy_to_user(data_arg.data, &temp, datasize))
 			return -EFAULT;
 	}
 	return res;
+}
+
+static int i2cdev_ioctl(struct inode *inode, struct file *file,
+		unsigned int cmd, unsigned long arg)
+{
+	struct i2c_client *client = (struct i2c_client *)file->private_data;
+	unsigned long funcs;
+
+	dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
+		cmd, arg);
+
+	switch ( cmd ) {
+	case I2C_SLAVE:
+	case I2C_SLAVE_FORCE:
+		/* NOTE:  devices set up to work with "new style" drivers
+		 * can't use I2C_SLAVE, even when the device node is not
+		 * bound to a driver.  Only I2C_SLAVE_FORCE will work.
+		 *
+		 * Setting the PEC flag here won't affect kernel drivers,
+		 * which will be using the i2c_client node registered with
+		 * the driver model core.  Likewise, when that client has
+		 * the PEC flag already set, the i2c-dev driver won't see
+		 * (or use) this setting.
+		 */
+		if ((arg > 0x3ff) ||
+		    (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
+			return -EINVAL;
+		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:
+		if (arg)
+			client->flags |= I2C_M_TEN;
+		else
+			client->flags &= ~I2C_M_TEN;
+		return 0;
+	case I2C_PEC:
+		if (arg)
+			client->flags |= I2C_CLIENT_PEC;
+		else
+			client->flags &= ~I2C_CLIENT_PEC;
+		return 0;
+	case I2C_FUNCS:
+		funcs = i2c_get_functionality(client->adapter);
+		return put_user(funcs, (unsigned long __user *)arg);
+
+	case I2C_RDWR:
+		return i2cdev_ioctl_rdrw(client, arg);
+
+	case I2C_SMBUS:
+		return i2cdev_ioctl_smbus(client, arg);
+
 	case I2C_RETRIES:
 		client->adapter->retries = arg;
 		break;