linux-kernel - Re: [PATCH V1 3/3] rpmsg: char: Add TIOCMGET/TIOCMSET ioctl support

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Date:   Thu, 30 Sep 2021 09:36:28 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Deepak Kumar Singh <deesin@...eaurora.org>,
        bjorn.andersson@...aro.org, clew@...eaurora.org,
        mathieu.poirier@...aro.org
Cc:     linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-remoteproc@...r.kernel.org, Ohad Ben-Cohen <ohad@...ery.com>
Subject: Re: [PATCH V1 3/3] rpmsg: char: Add TIOCMGET/TIOCMSET ioctl support

Quoting Deepak Kumar Singh (2021-09-30 08:32:04)
> Add TICOMGET and TIOCMSET ioctl support for rpmsg char device nodes
> to get/set the low level transport signals.
>
> Signed-off-by: Chris Lew <clew@...eaurora.org>

Is Chris the author? Because if so then there should be a From: Chris
line before the commit text starts.

> Signed-off-by: Deepak Kumar Singh <deesin@...eaurora.org>
> ---
>  drivers/rpmsg/rpmsg_char.c | 43 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 43 insertions(+)
>
> diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
> index 2bebc9b..60a889b 100644
> --- a/drivers/rpmsg/rpmsg_char.c
> +++ b/drivers/rpmsg/rpmsg_char.c
> @@ -19,6 +19,7 @@
>  #include <linux/rpmsg.h>
>  #include <linux/skbuff.h>
>  #include <linux/slab.h>
> +#include <linux/termios.h>
>  #include <linux/uaccess.h>
>  #include <uapi/linux/rpmsg.h>
>
> @@ -76,6 +77,9 @@ struct rpmsg_eptdev {
>         spinlock_t queue_lock;
>         struct sk_buff_head queue;
>         wait_queue_head_t readq;
> +
> +       u32 rsigs;
> +       bool sig_pending;
>  };
>
>  static int rpmsg_eptdev_destroy(struct device *dev, void *data)
> @@ -120,6 +124,18 @@ static int rpmsg_ept_cb(struct rpmsg_device *rpdev, void *buf, int len,
>         return 0;
>  }
>
> +static int rpmsg_sigs_cb(struct rpmsg_device *rpdev, void *priv, u32 sigs)
> +{
> +       struct rpmsg_eptdev *eptdev = priv;
> +
> +       eptdev->rsigs = sigs;
> +       eptdev->sig_pending = true;
> +
> +       /* wake up any blocking processes, waiting for signal notification */

Comment would be better if it indicated what function these waiters are
in instead of saying what wake_up_interruptible() does. Also, what is
interruptible for?

> +       wake_up_interruptible(&eptdev->readq);

Nitpick: Add newline here.

> +       return 0;
> +}
> +
>  static int rpmsg_eptdev_open(struct inode *inode, struct file *filp)
>  {
>         struct rpmsg_eptdev *eptdev = cdev_to_eptdev(inode->i_cdev);
> @@ -276,10 +297,32 @@ static long rpmsg_eptdev_ioctl(struct file *fp, unsigned int cmd,
>                                unsigned long arg)
>  {
>         struct rpmsg_eptdev *eptdev = fp->private_data;
> +       bool set;
> +       u32 val;
> +       int ret;
>
>         if (cmd != RPMSG_DESTROY_EPT_IOCTL)
>                 return -EINVAL;

This should be deleted?

>
> +       switch (cmd) {
> +       case TIOCMGET:
> +               eptdev->sig_pending = false;
> +               ret = put_user(eptdev->rsigs, (int __user *)arg);
> +               break;
> +       case TIOCMSET:
> +               ret = get_user(val, (int __user *)arg);
> +               if (ret)
> +                       break;
> +               set = (val & TIOCM_DTR) ? true : false;
> +               ret = rpmsg_set_flow_control(eptdev->ept, set);
> +               break;
> +       case RPMSG_DESTROY_EPT_IOCTL:
> +               ret = rpmsg_eptdev_destroy(&eptdev->dev, NULL);
> +               break;
> +       default:
> +               ret = -EINVAL;
> +       }
> +
>         return rpmsg_eptdev_destroy(&eptdev->dev, NULL);

This should be replaced with return ret?