[PATCH v3 6/6] platform/chrome: cros_ec_proto: Convert EC error codes to Linux error codes

[Guenter Roeck <linux@roeck-us.net>]

The EC reports a variety of error codes. Most of those, with the exception
of EC_RES_INVALID_VERSION, are converted to -EPROTO. As result, the actual
EC error code gets lost. Introduce cros_ec_map_error() to map EC error
codes to Linux error codes, and use it in cros_ec_cmd_xfer_status() to
report more meaningful errors to the caller. With this change, callers of
cros_ec_cmd_xfer_status() can implement a more distinguished action without
having to rely on the EC error code. At the same time, debugging is improved
in situations where the Linux error code is reported to userspace and/or in
the kernel log.

Cc: Gwendal Grignou <gwendal@chromium.org>
Cc: Yu-Hsuan Hsu <yuhsuan@chromium.org>
Cc: Prashant Malani <pmalani@chromium.org>
Cc: Brian Norris <briannorris@chromium.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
v3: Use -ENOPROTOOPT for EC_RES_INVALID_VERSION
    Implement function to convert error codes
v2: No change

 drivers/platform/chrome/cros_ec_proto.c | 52 ++++++++++++++++++++-----
 1 file changed, 42 insertions(+), 10 deletions(-)

diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
index e5bbec979a2a..a081b8245682 100644
--- a/drivers/platform/chrome/cros_ec_proto.c
+++ b/drivers/platform/chrome/cros_ec_proto.c
@@ -15,6 +15,43 @@
 
 #define EC_COMMAND_RETRIES	50
 
+static const int cros_ec_error_map[] = {
+	[EC_RES_INVALID_COMMAND] = -EOPNOTSUPP,
+	[EC_RES_ERROR] = -EIO,
+	[EC_RES_INVALID_PARAM] = -EINVAL,
+	[EC_RES_ACCESS_DENIED] = -EACCES,
+	[EC_RES_INVALID_RESPONSE] = -EPROTO,
+	[EC_RES_INVALID_VERSION] = -ENOPROTOOPT,
+	[EC_RES_INVALID_CHECKSUM] = -EBADMSG,
+	[EC_RES_IN_PROGRESS] = -EINPROGRESS,
+	[EC_RES_UNAVAILABLE] = -ENODATA,
+	[EC_RES_TIMEOUT] = -ETIMEDOUT,
+	[EC_RES_OVERFLOW] = -EOVERFLOW,
+	[EC_RES_INVALID_HEADER] = -EBADR,
+	[EC_RES_REQUEST_TRUNCATED] = -EBADR,
+	[EC_RES_RESPONSE_TOO_BIG] = -EFBIG,
+	[EC_RES_BUS_ERROR] = -EFAULT,
+	[EC_RES_BUSY] = -EBUSY,
+	[EC_RES_INVALID_HEADER_VERSION] = -EBADMSG,
+	[EC_RES_INVALID_HEADER_CRC] = -EBADMSG,
+	[EC_RES_INVALID_DATA_CRC] = -EBADMSG,
+	[EC_RES_DUP_UNAVAILABLE] = -ENODATA,
+};
+
+static int cros_ec_map_error(uint32_t result)
+{
+	int ret = 0;
+
+	if (result != EC_RES_SUCCESS) {
+		if (result < ARRAY_SIZE(cros_ec_error_map) && cros_ec_error_map[result])
+			ret = cros_ec_error_map[result];
+		else
+			ret = -EPROTO;
+	}
+
+	return ret;
+}
+
 static int prepare_packet(struct cros_ec_device *ec_dev,
 			  struct cros_ec_command *msg)
 {
@@ -555,8 +592,7 @@ EXPORT_SYMBOL(cros_ec_cmd_xfer);
  *
  * Return:
  * >=0 - The number of bytes transferred
- * -ENOPROTOOPT - Operation not supported
- * -EPROTO - Protocol error
+ * <0 - Linux error code
  */
 int cros_ec_cmd_xfer_status(struct cros_ec_device *ec_dev,
 			    struct cros_ec_command *msg)
@@ -566,15 +602,11 @@ int cros_ec_cmd_xfer_status(struct cros_ec_device *ec_dev,
 	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_INVALID_VERSION) {
-		dev_dbg(ec_dev->dev, "Command invalid version (err:%d)\n",
-			msg->result);
-		return -ENOPROTOOPT;
-	} else if (msg->result != EC_RES_SUCCESS) {
-		dev_dbg(ec_dev->dev, "Command result (err: %d)\n", msg->result);
-		return -EPROTO;
+	} else {
+		ret = cros_ec_map_error(msg->result);
+		if (ret)
+			dev_dbg(ec_dev->dev, "Command result (err: %d [%d])\n", msg->result, ret);
 	}
-
 	return ret;
 }
 EXPORT_SYMBOL(cros_ec_cmd_xfer_status);
-- 
2.17.1