From a7b121b4b8b0bcc14fc1c2a81d34096109a65dd6 Mon Sep 17 00:00:00 2001 From: Martin Hundebøll Date: Mon, 12 Aug 2019 23:12:43 +0200 Subject: tty: n_gsm: add ioctl to map serial device to mux'ed tty MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Link: https://lore.kernel.org/r/20190812211243.98686-1-martin@geanix.com Signed-off-by: Greg Kroah-Hartman --- Documentation/driver-api/serial/n_gsm.rst | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'Documentation/driver-api') diff --git a/Documentation/driver-api/serial/n_gsm.rst b/Documentation/driver-api/serial/n_gsm.rst index 0ba731ab00b2..286e7ff4d2d9 100644 --- a/Documentation/driver-api/serial/n_gsm.rst +++ b/Documentation/driver-api/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, Major parts of the initialization program : (a good starting point is util-linux-ng/sys-utils/ldattach.c):: + #include + #include #include #include #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 -- cgit