linux-kernel - Re: [PATCH 2/4] platform/chrome: cros_ec_proto: factor legacy out from cros_ec_prepare

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Date:   Wed, 18 May 2022 09:26:13 -0700
From:   Guenter Roeck <groeck@...gle.com>
To:     Tzung-Bi Shih <tzungbi@...nel.org>
Cc:     Benson Leung <bleung@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        chrome-platform@...ts.linux.dev,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Doug Anderson <dianders@...omium.org>
Subject: Re: [PATCH 2/4] platform/chrome: cros_ec_proto: factor legacy out
 from cros_ec_prepare_tx()

On Wed, May 18, 2022 at 2:18 AM Tzung-Bi Shih <tzungbi@...nel.org> wrote:
>
> 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@...nel.org>

Reviewed-by: Guenter Roeck <groeck@...omium.org>

> ---
>  drivers/platform/chrome/cros_ec_proto.c | 51 ++++++++++++++-----------
>  1 file changed, 28 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
> index ff767dccdf0f..01ab58b3269b 100644
> --- 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);
>
> --
> 2.36.0.550.gb090851708-goog
>