redonkable
/
alistair23-linux
1
0
Fork 0
Code Releases Activity

tty: n_gsm: add ioctl to map serial device to mux'ed tty 

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 <martin@geanix.com>
Link: https://lore.kernel.org/r/20190812211243.98686-1-martin@geanix.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
alistair/sunxi64-5.4-dsi
Martin Hundebøll 2019-08-12 23:12:43 +02:00 committed by Greg Kroah-Hartman
parent d193db7fb1
commit a7b121b4b8
3 changed files with 15 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
Documentation/driver-api/serial/n_gsm.rst
View File

@ -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,
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

4
drivers/tty/n_gsm.c
View File

@ -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, (__u32 __user *)arg);
default:
return n_tty_ioctl_helper(tty, file, cmd, arg);
}

2
include/uapi/linux/gsmmux.h
View File

@ -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, __u32)
#endif