linux-kernel - Re: [PATCHv2 07/11] serdev: add helpers for cts and rts handling

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Date:   Wed, 22 Mar 2017 16:03:14 -0500
From:   Rob Herring <robh+dt@...nel.org>
To:     Sebastian Reichel <sre@...nel.org>
Cc:     Marcel Holtmann <marcel@...tmann.org>,
        Gustavo Padovan <gustavo@...ovan.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Samuel Thibault <samuel.thibault@...-lyon.org>,
        Pavel Machek <pavel@....cz>, Tony Lindgren <tony@...mide.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>,
        Mark Rutland <mark.rutland@....com>,
        "open list:BLUETOOTH DRIVERS" <linux-bluetooth@...r.kernel.org>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCHv2 07/11] serdev: add helpers for cts and rts handling

On Tue, Mar 21, 2017 at 5:32 PM, Sebastian Reichel <sre@...nel.org> wrote:
> Add serdev helper functions for handling of cts and rts
> lines using the serdev's tiocm functions.
>
> Signed-off-by: Sebastian Reichel <sre@...nel.org>
> ---
>  include/linux/serdev.h | 31 +++++++++++++++++++++++++++++++
>  1 file changed, 31 insertions(+)
>
> diff --git a/include/linux/serdev.h b/include/linux/serdev.h
> index 3ad1d695f947..8cdce2ea0d51 100644
> --- a/include/linux/serdev.h
> +++ b/include/linux/serdev.h
> @@ -16,6 +16,7 @@
>  #include <linux/types.h>
>  #include <linux/device.h>
>  #include <asm-generic/termios.h>
> +#include <linux/delay.h>
>
>  struct serdev_controller;
>  struct serdev_device;
> @@ -254,6 +255,36 @@ static inline int serdev_device_write_room(struct serdev_device *sdev)
>
>  #endif /* CONFIG_SERIAL_DEV_BUS */
>
> +static inline bool serdev_device_get_cts(struct serdev_device *serdev)
> +{
> +       int status = serdev_device_get_tiocm(serdev);
> +       return !!(status & TIOCM_CTS);
> +}
> +
> +static inline int serdev_device_wait_for_cts(struct serdev_device *serdev, bool state, int timeout_ms)
> +{
> +       unsigned long timeout;
> +       bool signal;
> +
> +       timeout = jiffies + msecs_to_jiffies(timeout_ms);
> +       while (!time_after(jiffies, timeout)) {

You can use time_is_after_jiffies(timeout) instead of !time_after.

> +               signal = serdev_device_get_cts(serdev);
> +               if (signal == state)
> +                       return 0;
> +               usleep_range(1000, 2000);
> +       }
> +
> +       return -ETIMEDOUT;
> +}
> +
> +static inline int serdev_device_set_rts(struct serdev_device *serdev, bool enable)
> +{
> +       if (enable)
> +               return serdev_device_set_tiocm(serdev, TIOCM_OUT2 | TIOCM_RTS, 0);

Perhaps a comment why we're messing with OUT2.

With those,

Acked-by: Rob Herring <robh@...nel.org>

> +       else
> +               return serdev_device_set_tiocm(serdev, 0, TIOCM_OUT2 | TIOCM_RTS);
> +}
> +
>  /*
>   * serdev hooks into TTY core
>   */
> --
> 2.11.0
>