i2c: stu300: use xfer_atomic callback to bail out early

Use the new callback to reject atomic transfers.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/i2c-stu300.c

@@ -328,12 +328,6 @@ static int stu300_start_and_await_event(struct stu300_dev *dev,
 {
 	int ret;
 
-	if (unlikely(irqs_disabled())) {
-		/* TODO: implement polling for this case if need be. */
-		WARN(1, "irqs are disabled, cannot poll for event\n");
-		return -EIO;
-	}
-
 	/* Lock command issue, fill in an event we wait for */
 	spin_lock_irq(&dev->cmd_issue_lock);
 	init_completion(&dev->cmd_complete);
@@ -380,13 +374,6 @@ static int stu300_await_event(struct stu300_dev *dev,
 {
 	int ret;
 
-	if (unlikely(irqs_disabled())) {
-		/* TODO: implement polling for this case if need be. */
-		dev_err(&dev->pdev->dev, "irqs are disabled on this "
-			"system!\n");
-		return -EIO;
-	}
-
 	/* Is it already here? */
 	spin_lock_irq(&dev->cmd_issue_lock);
 	dev->cmd_err = STU300_ERROR_NONE;
@@ -846,6 +833,13 @@ static int stu300_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 	return num;
 }
 
+static int stu300_xfer_todo(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
+{
+	/* TODO: implement polling for this case if need be. */
+	WARN(1, "%s: atomic transfers not implemented\n", dev_name(&adap->dev));
+	return -EOPNOTSUPP;
+}
+
 static u32 stu300_func(struct i2c_adapter *adap)
 {
 	/* This is the simplest thing you can think of... */
@@ -854,6 +848,7 @@ static u32 stu300_func(struct i2c_adapter *adap)
 
 static const struct i2c_algorithm stu300_algo = {
 	.master_xfer = stu300_xfer,
+	.master_xfer_atomic = stu300_xfer_todo,
 	.functionality = stu300_func,
 };