Documentation: tty: n_gsm, use power of ReST

Reformat the whole document, so that automatic numbering and TOC is
properly generated.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220411110143.10019-7-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/driver-api/tty/n_gsm.rst

@@ -2,6 +2,8 @@
 GSM 0710 tty multiplexor HOWTO
 ==============================
 
+.. contents:: :local:
+
 This line discipline implements the GSM 07.10 multiplexing protocol
 detailed in the following 3GPP document:
 
@@ -11,28 +13,30 @@ This document give some hints on how to use this driver with GPRS and 3G
 modems connected to a physical serial port.
 
 How to use it
--------------
-1. config initiator
-^^^^^^^^^^^^^^^^^^^^^
+=============
+
+Config Initiator
+----------------
 
-1.1 initialize the modem in 0710 mux mode (usually AT+CMUX= command) through
+#. Initialize the modem in 0710 mux mode (usually ``AT+CMUX=`` command) through
    its serial port. Depending on the modem used, you can pass more or less
    parameters to this command.
 
-1.2 switch the serial line to using the n_gsm line discipline by using
-    TIOCSETD ioctl.
+#. Switch the serial line to using the n_gsm line discipline by using
+   ``TIOCSETD`` ioctl.
 
-1.3 configure the mux using GSMIOC_GETCONF / GSMIOC_SETCONF ioctl.
+#. Configure the mux using ``GSMIOC_GETCONF``/``GSMIOC_SETCONF`` ioctl.
 
-1.4 obtain base gsmtty number for the used serial port.
+#. 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)::
+   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
       #define SERIAL_PORT	/dev/ttyS0
 
@@ -76,14 +80,14 @@ Major parts of the initialization program :
       daemon(0,0);
       pause();
 
-1.5 use these devices as plain serial ports.
+#. Use these devices as plain serial ports.
 
-   for example, it's possible:
+   For example, it's possible:
 
-   - and to use gnokii to send / receive SMS on ttygsm1
-   - to use ppp to establish a datalink on ttygsm2
+   - to use *gnokii* to send / receive SMS on ``ttygsm1``
+   - to use *ppp* to establish a datalink on ``ttygsm2``
 
-1.6 first close all virtual ports before closing the physical port.
+#. 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
@@ -91,20 +95,20 @@ Major parts of the initialization program :
    a disconnect command frame manually before initializing the multiplexing mode
    for the second time. The byte sequence for the disconnect command frame is::
 
-      0xf9, 0x03, 0xef, 0x03, 0xc3, 0x16, 0xf9.
+      0xf9, 0x03, 0xef, 0x03, 0xc3, 0x16, 0xf9
 
-2. config requester
-^^^^^^^^^^^^^^^^^^^^^
+Config Requester
+----------------
 
-2.1 receive string "AT+CMUX= command" through its serial port,initialize
-    mux mode config
+#. Receive ``AT+CMUX=`` command through its serial port, initialize mux mode
+   config.
 
-2.2 switch the serial line to using the n_gsm line discipline by using
-    TIOCSETD ioctl.
+#. Switch the serial line to using the *n_gsm* line discipline by using
+   ``TIOCSETD`` ioctl.
 
-2.3 configure the mux using GSMIOC_GETCONF / GSMIOC_SETCONF ioctl.
+#. Configure the mux using ``GSMIOC_GETCONF``/``GSMIOC_SETCONF`` ioctl.
 
-2.4 obtain base gsmtty number for the used serial port::
+#. Obtain base gsmtty number for the used serial port::
 
         #include <stdio.h>
         #include <stdint.h>