[PATCH v2 1/2] platform/chrome: cros_ec_proto: Introduce cros_ec_read_features helper

Extract the EC feature-reading logic from cros_ec_check_features() into
cros_ec_read_features() helper function.

Currently, cros_ec_check_features() swallows command transfer errors. By
isolating the transaction logic into an explicit helper that returns the
actual transfer error code, subsequent callers (such as the cros_ec_dev
driver during device probing) can catch a read error.

Signed-off-by: Andrei Kuchynski <[email protected]>
Acked-by: Tzung-Bi Shih <[email protected]>
---
 drivers/platform/chrome/cros_ec_proto.c     | 30 +++++++++++++++------
 include/linux/platform_data/cros_ec_proto.h |  2 ++
 2 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
index 1d8d9168ec1aa..724d1313f6b21 100644
--- a/drivers/platform/chrome/cros_ec_proto.c
+++ b/drivers/platform/chrome/cros_ec_proto.c
@@ -946,6 +946,27 @@ u32 cros_ec_get_host_event(struct cros_ec_device *ec_dev)
 }
 EXPORT_SYMBOL(cros_ec_get_host_event);
 
+/**
+ * cros_ec_read_features() - Read EC features
+ *
+ * @ec: EC device.
+ *
+ * Return: >= 0 on success, negative error number on failure.
+ */
+int cros_ec_read_features(struct cros_ec_dev *ec)
+{
+	int ret = cros_ec_cmd(ec->ec_dev, 0, EC_CMD_GET_FEATURES + ec->cmd_offset,
+			      NULL, 0, &ec->features, sizeof(ec->features));
+
+	if (ret < 0) {
+		dev_warn(ec->dev, "cannot get EC features: %d\n", ret);
+		memset(&ec->features, 0, sizeof(ec->features));
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(cros_ec_read_features);
+
 /**
  * cros_ec_check_features() - Test for the presence of EC features
  *
@@ -960,17 +981,10 @@ EXPORT_SYMBOL(cros_ec_get_host_event);
 bool cros_ec_check_features(struct cros_ec_dev *ec, int feature)
 {
 	struct ec_response_get_features *features = &ec->features;
-	int ret;
 
 	if (features->flags[0] == -1U && features->flags[1] == -1U) {
 		/* features bitmap not read yet */
-		ret = cros_ec_cmd(ec->ec_dev, 0, EC_CMD_GET_FEATURES + ec->cmd_offset,
-				  NULL, 0, features, sizeof(*features));
-		if (ret < 0) {
-			dev_warn(ec->dev, "cannot get EC features: %d\n", ret);
-			memset(features, 0, sizeof(*features));
-		}
-
+		cros_ec_read_features(ec);
 		dev_dbg(ec->dev, "EC features %08x %08x\n",
 			features->flags[0], features->flags[1]);
 	}
diff --git a/include/linux/platform_data/cros_ec_proto.h b/include/linux/platform_data/cros_ec_proto.h
index 6ed1c4c5ce2ef..a1ccecf5e1f83 100644
--- a/include/linux/platform_data/cros_ec_proto.h
+++ b/include/linux/platform_data/cros_ec_proto.h
@@ -271,6 +271,8 @@ int cros_ec_get_next_event(struct cros_ec_device *ec_dev,
 
 u32 cros_ec_get_host_event(struct cros_ec_device *ec_dev);
 
+int cros_ec_read_features(struct cros_ec_dev *ec);
+
 bool cros_ec_check_features(struct cros_ec_dev *ec, int feature);
 
 int cros_ec_get_sensor_count(struct cros_ec_dev *ec);
-- 
2.54.0.1032.g2f8565e1d1-goog