Input: convert force feedback documentation into ReST format

This file require minimum adjustments to be a valid ReST file.
Do it, in order to be able to parse it with Sphinx.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/input/ff.txt

@@ -1,12 +1,16 @@
-Force feedback for Linux.
+========================
-By Johann Deneux <johann.deneux@gmail.com> on 2001/04/22.
+Force feedback for Linux
-Updated by Anssi Hannula <anssi.hannula@gmail.com> on 2006/04/09.
+========================
+
+:Author: Johann Deneux <johann.deneux@gmail.com> on 2001/04/22.
+:Updated: Anssi Hannula <anssi.hannula@gmail.com> on 2006/04/09.
+
 You may redistribute this file. Please remember to include shape.fig and
 interactive.fig as well.
-----------------------------------------------------------------------------
 
-1. Introduction
+Introduction
-~~~~~~~~~~~~~~~
+~~~~~~~~~~~~
+
 This document describes how to use force feedback devices under Linux. The
 goal is not to support these devices as if they were simple input-only devices
 (as it is already the case), but to really enable the rendering of force
@@ -15,8 +19,9 @@ This document only describes the force feedback part of the Linux input
 interface. Please read joystick.txt and input.txt before reading further this
 document.
 
-2. Instructions to the user
+Instructions to the user
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
+~~~~~~~~~~~~~~~~~~~~~~~~
+
 To enable force feedback, you have to:
 
 1. have your kernel configured with evdev and a driver that supports your
@@ -33,39 +38,48 @@ something goes wrong.
 If you have a serial iforce device, you need to start inputattach. See
 joystick.txt for details.
 
-2.1 Does it work ?
+Does it work ?
-~~~~~~~~~~~~~~~~~~
+--------------
-There is an utility called fftest that will allow you to test the driver.
+
-% fftest /dev/input/eventXX
+There is an utility called fftest that will allow you to test the driver::
+
+    % fftest /dev/input/eventXX
+
+Instructions to the developer
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-3. Instructions to the developer
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 All interactions are done using the event API. That is, you can use ioctl()
 and write() on /dev/input/eventXX.
 This information is subject to change.
 
-3.1 Querying device capabilities
+Querying device capabilities
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+----------------------------
-#include <linux/input.h>
-#include <sys/ioctl.h>
 
-#define BITS_TO_LONGS(x) \
+::
-	(((x) + 8 * sizeof (unsigned long) - 1) / (8 * sizeof (unsigned long)))
+
-unsigned long features[BITS_TO_LONGS(FF_CNT)];
+    #include <linux/input.h>
-int ioctl(int file_descriptor, int request, unsigned long *features);
+    #include <sys/ioctl.h>
+
+    #define BITS_TO_LONGS(x) \
+	    (((x) + 8 * sizeof (unsigned long) - 1) / (8 * sizeof (unsigned long)))
+    unsigned long features[BITS_TO_LONGS(FF_CNT)];
+    int ioctl(int file_descriptor, int request, unsigned long *features);
 
 "request" must be EVIOCGBIT(EV_FF, size of features array in bytes )
 
 Returns the features supported by the device. features is a bitfield with the
 following bits:
+
 - FF_CONSTANT	can render constant force effects
 - FF_PERIODIC	can render periodic effects with the following waveforms:
+
   - FF_SQUARE	  square waveform
   - FF_TRIANGLE	  triangle waveform
   - FF_SINE	  sine waveform
   - FF_SAW_UP	  sawtooth up waveform
   - FF_SAW_DOWN	  sawtooth down waveform
   - FF_CUSTOM	  custom waveform
+
 - FF_RAMP       can render ramp effects
 - FF_SPRING	can simulate the presence of a spring
 - FF_FRICTION	can simulate friction
@@ -75,24 +89,30 @@ following bits:
 - FF_GAIN	gain is adjustable
 - FF_AUTOCENTER	autocenter is adjustable
 
-Note: In most cases you should use FF_PERIODIC instead of FF_RUMBLE. All
+.. note::
+
+    - In most cases you should use FF_PERIODIC instead of FF_RUMBLE. All
       devices that support FF_RUMBLE support FF_PERIODIC (square, triangle,
       sine) and the other way around.
 
-Note: The exact syntax FF_CUSTOM is undefined for the time being as no driver
+    - The exact syntax FF_CUSTOM is undefined for the time being as no driver
       supports it yet.
 
+::
 
-int ioctl(int fd, EVIOCGEFFECTS, int *n);
+    int ioctl(int fd, EVIOCGEFFECTS, int *n);
 
 Returns the number of effects the device can keep in its memory.
 
-3.2 Uploading effects to the device
+Uploading effects to the device
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+-------------------------------
-#include <linux/input.h>
-#include <sys/ioctl.h>
 
-int ioctl(int file_descriptor, int request, struct ff_effect *effect);
+::
+
+    #include <linux/input.h>
+    #include <sys/ioctl.h>
+
+    int ioctl(int file_descriptor, int request, struct ff_effect *effect);
 
 "request" must be EVIOCSFF.
 
@@ -110,34 +130,41 @@ See <linux/input.h> for a description of the ff_effect struct. You should also
 find help in a few sketches, contained in files shape.fig and interactive.fig.
 You need xfig to visualize these files.
 
-3.3 Removing an effect from the device
+
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Removing an effect from the device
-int ioctl(int fd, EVIOCRMFF, effect.id);
+----------------------------------
+
+::
+
+    int ioctl(int fd, EVIOCRMFF, effect.id);
 
 This makes room for new effects in the device's memory. Note that this also
 stops the effect if it was playing.
 
-3.4 Controlling the playback of effects
+Controlling the playback of effects
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+-----------------------------------
+
 Control of playing is done with write(). Below is an example:
 
-#include <linux/input.h>
+::
-#include <unistd.h>
+
+    #include <linux/input.h>
+    #include <unistd.h>
 
 	struct input_event play;
 	struct input_event stop;
 	struct ff_effect effect;
 	int fd;
-...
+   ...
 	fd = open("/dev/input/eventXX", O_RDWR);
-...
+   ...
 	/* Play three times */
 	play.type = EV_FF;
 	play.code = effect.id;
 	play.value = 3;
 
 	write(fd, (const void*) &play, sizeof(play));
-...
+   ...
 	/* Stop an effect */
 	stop.type = EV_FF;
 	stop.code = effect.id;
@@ -145,43 +172,50 @@ Control of playing is done with write(). Below is an example:
 
 	write(fd, (const void*) &play, sizeof(stop));
 
-3.5 Setting the gain
+Setting the gain
-~~~~~~~~~~~~~~~~~~~~
+----------------
+
 Not all devices have the same strength. Therefore, users should set a gain
 factor depending on how strong they want effects to be. This setting is
 persistent across access to the driver.
 
-/* Set the gain of the device
+::
-int gain;		/* between 0 and 100 */
-struct input_event ie;	/* structure used to communicate with the driver */
 
-ie.type = EV_FF;
+    /* Set the gain of the device
-ie.code = FF_GAIN;
+    int gain;		/* between 0 and 100 */
-ie.value = 0xFFFFUL * gain / 100;
+    struct input_event ie;	/* structure used to communicate with the driver */
 
-if (write(fd, &ie, sizeof(ie)) == -1)
+    ie.type = EV_FF;
+    ie.code = FF_GAIN;
+    ie.value = 0xFFFFUL * gain / 100;
+
+    if (write(fd, &ie, sizeof(ie)) == -1)
 	perror("set gain");
 
-3.6 Enabling/Disabling autocenter
+Enabling/Disabling autocenter
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+-----------------------------
+
 The autocenter feature quite disturbs the rendering of effects in my opinion,
 and I think it should be an effect, which computation depends on the game
 type. But you can enable it if you want.
 
-int autocenter;		/* between 0 and 100 */
+::
-struct input_event ie;
 
-ie.type = EV_FF;
+    int autocenter;		/* between 0 and 100 */
-ie.code = FF_AUTOCENTER;
+    struct input_event ie;
-ie.value = 0xFFFFUL * autocenter / 100;
 
-if (write(fd, &ie, sizeof(ie)) == -1)
+    ie.type = EV_FF;
+    ie.code = FF_AUTOCENTER;
+    ie.value = 0xFFFFUL * autocenter / 100;
+
+    if (write(fd, &ie, sizeof(ie)) == -1)
 	perror("set auto-center");
 
 A value of 0 means "no auto-center".
 
-3.7 Dynamic update of an effect
+Dynamic update of an effect
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+---------------------------
+
 Proceed as if you wanted to upload a new effect, except that instead of
 setting the id field to -1, you set it to the wanted effect id.
 Normally, the effect is not stopped and restarted. However, depending on the
@@ -192,30 +226,32 @@ case, the driver stops the effect, up-load it, and restart it.
 Therefore it is recommended to dynamically change direction while the effect
 is playing only when it is ok to restart the effect with a replay count of 1.
 
-3.8 Information about the status of effects
+Information about the status of effects
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+---------------------------------------
+
 Every time the status of an effect is changed, an event is sent. The values
-and meanings of the fields of the event are as follows:
+and meanings of the fields of the event are as follows::
 
-struct input_event {
+    struct input_event {
-/* When the status of the effect changed */
+    /* When the status of the effect changed */
-	struct timeval time;
+	    struct timeval time;
 
-/* Set to EV_FF_STATUS */
+    /* Set to EV_FF_STATUS */
-	unsigned short type;
+	    unsigned short type;
 
-/* Contains the id of the effect */
+    /* Contains the id of the effect */
-	unsigned short code;
+	    unsigned short code;
 
-/* Indicates the status */
+    /* Indicates the status */
-	unsigned int value;
+	    unsigned int value;
-};
+    };
 
-FF_STATUS_STOPPED	The effect stopped playing
+    FF_STATUS_STOPPED	The effect stopped playing
-FF_STATUS_PLAYING	The effect started to play
+    FF_STATUS_PLAYING	The effect started to play
 
-NOTE: Status feedback is only supported by iforce driver. If you have
+.. note::
+
+    - Status feedback is only supported by iforce driver. If you have
       a really good reason to use this, please contact
       linux-joystick@atrey.karlin.mff.cuni.cz or anssi.hannula@gmail.com
       so that support for it can be added to the rest of the drivers.
-