platform/chrome: cros_ec_proto: factor legacy out from cros_ec_prepare_tx()

cros_ec_prepare_tx() mixed the code for both versions.  To be neat and to
make it clear, factor the legacy part out as a separate function, rename
the function, and update the comments.

Specifically,
- prepare_tx(), for current protocol version (i.e. 3).
- prepare_tx_legacy(), for protocol version <= 2.

Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Link: https://lore.kernel.org/r/20220518091814.2028579-3-tzungbi@kernel.org

diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
index ff767dc..01ab58b 100644 (file)
--- a/drivers/platform/chrome/cros_ec_proto.c
+++ b/drivers/platform/chrome/cros_ec_proto.c
@@ -52,8 +52,8 @@ static int cros_ec_map_error(uint32_t result)
        return ret;
 }
 
-static int prepare_packet(struct cros_ec_device *ec_dev,
-                         struct cros_ec_command *msg)
+static int prepare_tx(struct cros_ec_device *ec_dev,
+                     struct cros_ec_command *msg)
 {
        struct ec_host_request *request;
        u8 *out;
@@ -85,6 +85,28 @@ static int prepare_packet(struct cros_ec_device *ec_dev,
        return sizeof(*request) + msg->outsize;
 }
 
+static int prepare_tx_legacy(struct cros_ec_device *ec_dev,
+                            struct cros_ec_command *msg)
+{
+       u8 *out;
+       u8 csum;
+       int i;
+
+       if (msg->outsize > EC_PROTO2_MAX_PARAM_SIZE)
+               return -EINVAL;
+
+       out = ec_dev->dout;
+       out[0] = EC_CMD_VERSION0 + msg->version;
+       out[1] = msg->command;
+       out[2] = msg->outsize;
+       csum = out[0] + out[1] + out[2];
+       for (i = 0; i < msg->outsize; i++)
+               csum += out[EC_MSG_TX_HEADER_BYTES + i] = msg->data[i];
+       out[EC_MSG_TX_HEADER_BYTES + msg->outsize] = csum;
+
+       return EC_MSG_TX_PROTO_BYTES + msg->outsize;
+}
+
 static int send_command(struct cros_ec_device *ec_dev,
                        struct cros_ec_command *msg)
 {
@@ -161,35 +183,18 @@ static int send_command(struct cros_ec_device *ec_dev,
  * @ec_dev: Device to register.
  * @msg: Message to write.
  *
- * This is intended to be used by all ChromeOS EC drivers, but at present
- * only SPI uses it. Once LPC uses the same protocol it can start using it.
- * I2C could use it now, with a refactor of the existing code.
+ * This is used by all ChromeOS EC drivers to prepare the outgoing message
+ * according to different protocol versions.
  *
  * Return: number of prepared bytes on success or negative error code.
  */
 int cros_ec_prepare_tx(struct cros_ec_device *ec_dev,
                       struct cros_ec_command *msg)
 {
-       u8 *out;
-       u8 csum;
-       int i;
-
        if (ec_dev->proto_version > 2)
-               return prepare_packet(ec_dev, msg);
-
-       if (msg->outsize > EC_PROTO2_MAX_PARAM_SIZE)
-               return -EINVAL;
-
-       out = ec_dev->dout;
-       out[0] = EC_CMD_VERSION0 + msg->version;
-       out[1] = msg->command;
-       out[2] = msg->outsize;
-       csum = out[0] + out[1] + out[2];
-       for (i = 0; i < msg->outsize; i++)
-               csum += out[EC_MSG_TX_HEADER_BYTES + i] = msg->data[i];
-       out[EC_MSG_TX_HEADER_BYTES + msg->outsize] = csum;
+               return prepare_tx(ec_dev, msg);
 
-       return EC_MSG_TX_PROTO_BYTES + msg->outsize;
+       return prepare_tx_legacy(ec_dev, msg);
 }
 EXPORT_SYMBOL(cros_ec_prepare_tx);