On Wed, Jul 10, 2019 at 09:26:56PM +0200, Martin Hundebøll wrote:
> Guessing the first tty for a gsm0710 multiplexed serial device is not
> currently possible, which makes it racy to use with multiple modems.
>
> Add a way to map the physical serial tty to its related mux devices
> using an ioctl.
>
> Signed-off-by: Martin Hundebøll <[email protected]>
> ---
>
> Changes since v2:
> * rename IOCTL from GSMIOC_GETBASE to GSMIOC_GETFIRST
> * return first usable line instead of private control line
> * return uint32_t instead of int
>
> Changes since v1:
> * use put_user() instead of copy_to_user()
> * add missing opening quote
>
> Documentation/serial/n_gsm.rst | 11 +++++++++--
> drivers/tty/n_gsm.c | 4 ++++
> include/uapi/linux/gsmmux.h | 2 ++
> 3 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/serial/n_gsm.rst b/Documentation/serial/n_gsm.rst
> index 0ba731ab00b2..286e7ff4d2d9 100644
> --- a/Documentation/serial/n_gsm.rst
> +++ b/Documentation/serial/n_gsm.rst
> @@ -18,10 +18,13 @@ How to use it
> 2. switch the serial line to using the n_gsm line discipline by using
> TIOCSETD ioctl,
> 3. configure the mux using GSMIOC_GETCONF / GSMIOC_SETCONF ioctl,
> +4. obtain base gsmtty number for the used serial port,
As this file is in .rst format, do we need the enumerated list anymore?
Just a meta-comment...
>
> Major parts of the initialization program :
> (a good starting point is util-linux-ng/sys-utils/ldattach.c)::
>
> + #include <stdio.h>
> + #include <stdint.h>
> #include <linux/gsmmux.h>
> #include <linux/tty.h>
> #define DEFAULT_SPEED B115200
> @@ -30,6 +33,7 @@ Major parts of the initialization program :
> int ldisc = N_GSM0710;
> struct gsm_config c;
> struct termios configuration;
> + uint32_t first;
>
> /* open the serial port connected to the modem */
> fd = open(SERIAL_PORT, O_RDWR | O_NOCTTY | O_NDELAY);
> @@ -58,19 +62,22 @@ Major parts of the initialization program :
> c.mtu = 127;
> /* set the new configuration */
> ioctl(fd, GSMIOC_SETCONF, &c);
> + /* get first gsmtty device node */
> + ioctl(fd, GSMIOC_GETFIRST, &first);
> + printf("first muxed line: /dev/gsmtty%i\n", first);
>
> /* and wait for ever to keep the line discipline enabled */
> daemon(0,0);
> pause();
>
> -4. use these devices as plain serial ports.
> +5. use these devices as plain serial ports.
>
> for example, it's possible:
>
> - and to use gnokii to send / receive SMS on ttygsm1
> - to use ppp to establish a datalink on ttygsm2
>
> -5. first close all virtual ports before closing the physical port.
> +6. first close all virtual ports before closing the physical port.
>
> Note that after closing the physical port the modem is still in
> multiplexing
> mode. This may prevent a successful re-opening of the port later. To avoid
> diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
> index a60be591f1fc..dac98f3ead3d 100644
> --- a/drivers/tty/n_gsm.c
> +++ b/drivers/tty/n_gsm.c
> @@ -2613,6 +2613,7 @@ static int gsmld_ioctl(struct tty_struct *tty, struct
> file *file,
> {
> struct gsm_config c;
> struct gsm_mux *gsm = tty->disc_data;
> + unsigned int base;
>
> switch (cmd) {
> case GSMIOC_GETCONF:
> @@ -2624,6 +2625,9 @@ static int gsmld_ioctl(struct tty_struct *tty, struct
> file *file,
> if (copy_from_user(&c, (void *)arg, sizeof(c)))
> return -EFAULT;
> return gsm_config(gsm, &c);
> + case GSMIOC_GETFIRST:
> + base = mux_num_to_base(gsm);
> + return put_user(base + 1, (uint32_t __user *)arg);
> default:
> return n_tty_ioctl_helper(tty, file, cmd, arg);
> }
> diff --git a/include/uapi/linux/gsmmux.h b/include/uapi/linux/gsmmux.h
> index 101d3c469acb..e292869245dc 100644
> --- a/include/uapi/linux/gsmmux.h
> +++ b/include/uapi/linux/gsmmux.h
> @@ -37,5 +37,7 @@ struct gsm_netconfig {
> #define GSMIOC_ENABLE_NET _IOW('G', 2, struct gsm_netconfig)
> #define GSMIOC_DISABLE_NET _IO('G', 3)
>
> +/* get the base tty number for a configured gsmmux tty */
> +#define GSMIOC_GETFIRST _IOR('G', 4, uint32_t)
Variables that cross the boundry from user/kernel should use the correct
type. That would be "__u32" here.
thanks.
greg k-h
