[PATCH v5 2/6] mfd: cros_ec: Add cros_ec_cmd_xfer_status helper

[Tomeu Vizoso <tomeu.vizoso@collabora.com>]

So that callers of cros_ec_cmd_xfer don't have to repeat boilerplate
code when checking for errors from the EC side.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
---

Changes in v5:
- Check explicitly for !EC_RES_SUCCESS as suggested by Benson Leung.

Changes in v4: None
Changes in v3: None
Changes in v2: None

 drivers/platform/chrome/cros_ec_proto.c | 14 ++++++++++++++
 include/linux/mfd/cros_ec.h             | 18 ++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
index c792e116e621..aaccdde1c9d5 100644
--- a/drivers/platform/chrome/cros_ec_proto.c
+++ b/drivers/platform/chrome/cros_ec_proto.c
@@ -472,3 +472,17 @@ int cros_ec_get_next_event(struct cros_ec_device *ec_dev)
 		return get_keyboard_state_event(ec_dev);
 }
 EXPORT_SYMBOL(cros_ec_get_next_event);
+
+int cros_ec_cmd_xfer_status(struct cros_ec_device *ec_dev,
+			    struct cros_ec_command *msg)
+{
+	int ret = cros_ec_cmd_xfer(ec_dev, msg);
+
+	if (ret < 0)
+		dev_err(ec_dev->dev, "Command xfer error (err:%d)\n", ret);
+	else if (msg->result != EC_RES_SUCCESS)
+		return -EECRESULT - msg->result;
+
+	return ret;
+}
+EXPORT_SYMBOL(cros_ec_cmd_xfer_status);
diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
index 1f88418a36cf..b6961c717209 100644
--- a/include/linux/mfd/cros_ec.h
+++ b/include/linux/mfd/cros_ec.h
@@ -40,6 +40,9 @@
 #define EC_MAX_REQUEST_OVERHEAD		1
 #define EC_MAX_RESPONSE_OVERHEAD	2
 
+/* ec_command return value for non-success result from EC */
+#define EECRESULT 1000
+
 /*
  * Command interface between EC and AP, for LPC, I2C and SPI interfaces.
  */
@@ -250,6 +253,21 @@ int cros_ec_cmd_xfer(struct cros_ec_device *ec_dev,
 		     struct cros_ec_command *msg);
 
 /**
+ * cros_ec_cmd_xfer_status - Send a command to the ChromeOS EC
+ *
+ * This function is identical to cros_ec_cmd_xfer, except it returns succes
+ * status only if both the command was transmitted successfully and the EC
+ * replied with success status. It's not necessary to check msg->result when
+ * using this function.
+ *
+ * @ec_dev: EC device
+ * @msg: Message to write
+ * @return: Num. of bytes transferred on success, <0 on failure
+ */
+int cros_ec_cmd_xfer_status(struct cros_ec_device *ec_dev,
+			    struct cros_ec_command *msg);
+
+/**
  * cros_ec_remove - Remove a ChromeOS EC
  *
  * Call this to deregister a ChromeOS EC, then clean up any private data.
-- 
2.5.0