platform/chrome: Re-introduce cros_ec_cmd_xfer and use it for ioctls

Commit 413dda8f2c6f ("platform/chrome: cros_ec_chardev: Use
cros_ec_cmd_xfer_status helper") inadvertendly changed the userspace ABI.
Previously, cros_ec ioctls would only report errors if the EC communication
failed, and otherwise return success and the result of the EC
communication. An EC command execution failure was reported in the EC
response field. The above mentioned commit changed this behavior, and the
ioctl itself would fail. This breaks userspace commands trying to analyze
the EC command execution error since the actual EC command response is no
longer reported to userspace.

Fix the problem by re-introducing the cros_ec_cmd_xfer() helper, and use it
to handle ioctl messages.

Fixes: 413dda8f2c6f ("platform/chrome: cros_ec_chardev: Use cros_ec_cmd_xfer_status helper")
Cc: Daisuke Nojiri <dnojiri@chromium.org>
Cc: Rob Barnes <robbarnes@google.com>
Cc: Rajat Jain <rajatja@google.com>
Cc: Brian Norris <briannorris@chromium.org>
Cc: Parth Malkan <parthmalkan@google.com>
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>

diff --git a/drivers/platform/chrome/cros_ec_chardev.c b/drivers/platform/chrome/cros_ec_chardev.c
index e0bce869c49a92d7af698137a92dc6726e1977c7..fd33de546aee0bb5ccea837e6fa2214cffa90014 100644 (file)
--- a/drivers/platform/chrome/cros_ec_chardev.c
+++ b/drivers/platform/chrome/cros_ec_chardev.c
@@ -301,7 +301,7 @@ static long cros_ec_chardev_ioctl_xcmd(struct cros_ec_dev *ec, void __user *arg)
        }
 
        s_cmd->command += ec->cmd_offset;
-       ret = cros_ec_cmd_xfer_status(ec->ec_dev, s_cmd);
+       ret = cros_ec_cmd_xfer(ec->ec_dev, s_cmd);
        /* Only copy data to userland if data was received. */
        if (ret < 0)
                goto exit;

diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
index c4caf2e2de825fda873878bd448bef3406a5f498..ac1419881ff358d705856db96378ca3e4a11a841 100644 (file)
--- a/drivers/platform/chrome/cros_ec_proto.c
+++ b/drivers/platform/chrome/cros_ec_proto.c
@@ -560,22 +560,28 @@ exit:
 EXPORT_SYMBOL(cros_ec_query_all);
 
 /**
- * cros_ec_cmd_xfer_status() - Send a command to the ChromeOS EC.
+ * cros_ec_cmd_xfer() - Send a command to the ChromeOS EC.
  * @ec_dev: EC device.
  * @msg: Message to write.
  *
- * Call this to send a command to the ChromeOS EC. This should be used instead of calling the EC's
- * cmd_xfer() callback directly. It returns success status only if both the command was transmitted
- * successfully and the EC replied with success status.
+ * Call this to send a command to the ChromeOS EC. This should be used instead
+ * of calling the EC's cmd_xfer() callback directly. This function does not
+ * convert EC command execution error codes to Linux error codes. Most
+ * in-kernel users will want to use cros_ec_cmd_xfer_status() instead since
+ * that function implements the conversion.
  *
  * Return:
- * >=0 - The number of bytes transferred
- * <0 - Linux error code
+ * >0 - EC command was executed successfully. The return value is the number
+ *      of bytes returned by the EC (excluding the header).
+ * =0 - EC communication was successful. EC command execution results are
+ *      reported in msg->result. The result will be EC_RES_SUCCESS if the
+ *      command was executed successfully or report an EC command execution
+ *      error.
+ * <0 - EC communication error. Return value is the Linux error code.
  */
-int cros_ec_cmd_xfer_status(struct cros_ec_device *ec_dev,
-                           struct cros_ec_command *msg)
+int cros_ec_cmd_xfer(struct cros_ec_device *ec_dev, struct cros_ec_command *msg)
 {
-       int ret, mapped;
+       int ret;
 
        mutex_lock(&ec_dev->lock);
        if (ec_dev->proto_version == EC_PROTO_VERSION_UNKNOWN) {
@@ -616,6 +622,32 @@ int cros_ec_cmd_xfer_status(struct cros_ec_device *ec_dev,
        ret = send_command(ec_dev, msg);
        mutex_unlock(&ec_dev->lock);
 
+       return ret;
+}
+EXPORT_SYMBOL(cros_ec_cmd_xfer);
+
+/**
+ * cros_ec_cmd_xfer_status() - Send a command to the ChromeOS EC.
+ * @ec_dev: EC device.
+ * @msg: Message to write.
+ *
+ * Call this to send a command to the ChromeOS EC. This should be used instead of calling the EC's
+ * cmd_xfer() callback directly. It returns success status only if both the command was transmitted
+ * successfully and the EC replied with success status.
+ *
+ * Return:
+ * >=0 - The number of bytes transferred.
+ * <0 - Linux error code
+ */
+int cros_ec_cmd_xfer_status(struct cros_ec_device *ec_dev,
+                           struct cros_ec_command *msg)
+{
+       int ret, mapped;
+
+       ret = cros_ec_cmd_xfer(ec_dev, msg);
+       if (ret < 0)
+               return ret;
+
        mapped = cros_ec_map_error(msg->result);
        if (mapped) {
                dev_dbg(ec_dev->dev, "Command result (err: %d [%d])\n",

diff --git a/include/linux/platform_data/cros_ec_proto.h b/include/linux/platform_data/cros_ec_proto.h
index c65971ec90eabe42518aa17cd6d0b41c404eb63d..138fd912c808e7f26fac3f6033b2cfc71d9b79c4 100644 (file)
--- a/include/linux/platform_data/cros_ec_proto.h
+++ b/include/linux/platform_data/cros_ec_proto.h
@@ -213,6 +213,9 @@ int cros_ec_prepare_tx(struct cros_ec_device *ec_dev,
 int cros_ec_check_result(struct cros_ec_device *ec_dev,
                         struct cros_ec_command *msg);
 
+int cros_ec_cmd_xfer(struct cros_ec_device *ec_dev,
+                    struct cros_ec_command *msg);
+
 int cros_ec_cmd_xfer_status(struct cros_ec_device *ec_dev,
                            struct cros_ec_command *msg);