mfd: cros_ec: stop calling ->cmd_xfer() directly

Instead of having users of the ChromeOS EC call the interface-specific
cmd_xfer() callback directly, introduce a central cros_ec_cmd_xfer()
to use instead.  This will allow us to put all the locking and retry
logic in one place instead of duplicating it across the different
drivers.

Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
diff --git a/drivers/i2c/busses/i2c-cros-ec-tunnel.c b/drivers/i2c/busses/i2c-cros-ec-tunnel.c
index 05e033c..43be23d 100644
--- a/drivers/i2c/busses/i2c-cros-ec-tunnel.c
+++ b/drivers/i2c/busses/i2c-cros-ec-tunnel.c
@@ -227,7 +227,7 @@
 	msg.indata = response;
 	msg.insize = response_len;
 
-	result = bus->ec->cmd_xfer(bus->ec, &msg);
+	result = cros_ec_cmd_xfer(bus->ec, &msg);
 	if (result < 0)
 		goto exit;
 
diff --git a/drivers/input/keyboard/cros_ec_keyb.c b/drivers/input/keyboard/cros_ec_keyb.c
index 791781a..93111d1 100644
--- a/drivers/input/keyboard/cros_ec_keyb.c
+++ b/drivers/input/keyboard/cros_ec_keyb.c
@@ -182,7 +182,7 @@
 		.insize = ckdev->cols,
 	};
 
-	return ckdev->ec->cmd_xfer(ckdev->ec, &msg);
+	return cros_ec_cmd_xfer(ckdev->ec, &msg);
 }
 
 static irqreturn_t cros_ec_keyb_irq(int irq, void *data)
diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
index 4873f9c..a9faebd 100644
--- a/drivers/mfd/cros_ec.c
+++ b/drivers/mfd/cros_ec.c
@@ -62,6 +62,13 @@
 }
 EXPORT_SYMBOL(cros_ec_check_result);
 
+int cros_ec_cmd_xfer(struct cros_ec_device *ec_dev,
+		     struct cros_ec_command *msg)
+{
+	return ec_dev->cmd_xfer(ec_dev, msg);
+}
+EXPORT_SYMBOL(cros_ec_cmd_xfer);
+
 static const struct mfd_cell cros_devs[] = {
 	{
 		.name = "cros-ec-keyb",