Add instructions on udev autorun

2 files changed, 64 insertions, 2 deletions

diff --git a/Readme.md b/Readme.md
index ef21d32..826d15e 100644
--- a/Readme.md
+++ b/Readme.md
@@ -54,7 +54,7 @@ Device D0:BC:C1:A2:BE:9F Wireless Controller
 
 Perfect! We've got a connection.
 
-## Run
+## Run manually
 
 First of all you need to be able to open `/dev/uinput` as a user, unless you
 decided to do everything from root. Do this for your `user` as root if you want
@@ -102,7 +102,26 @@ Then run the program like this:
 ./main /dev/input/event23
 ```
 
-## Usage 
+## Run automatically via udev
+
+If you want to run the program every time you connect the gamepad the following instruction may help. Or may not, who knows. At least it worked out for me.
+
+Copy `ds4-keyboard-udev-autorun.sh` and `main` files from this repo somewhere to be convenient for you. For example I put them both in `/etc/udev/rules.d` directory.
+
+Create a file `/etc/udev/rules.d/50-ds4.rules` and add the following contents:
+
+```
+SUBSYSTEM=="input", ATTRS{idVendor}=="054c", ATTRS{idProduct}=="05c4", RUN+="/etc/udev/rules.d/ds4-keyboard-udev-autorun.sh $devpath /etc/udev/rules.d/main"
+SUBSYSTEM=="input", ATTRS{idVendor}=="054c", ATTRS{idProduct}=="09cc", RUN+="/etc/udev/rules.d/ds4-keyboard-udev-autorun.sh $devpath /etc/udev/rules.d/main"
+```
+
+To make `udev` use new rules and re-trigger events to execute them right away without rebooting, you can run the following command as root:
+
+```
+udevadm control --reload-rules && udevadm trigger
+```
+
+## Usage
 
 Now you can issue keyboard keypresses by pressing some combinations of the gamepad buttons as shown in the following chart:
 
diff --git a/ds4-keyboard-udev-autorun.sh b/ds4-keyboard-udev-autorun.sh
new file mode 100755
index 0000000..7d4ead3
--- /dev/null
+++ b/ds4-keyboard-udev-autorun.sh
@@ -0,0 +1,43 @@
+#!/bin/bash
+
+# Program will just exit on any failed check (an expression in square brackets) due to -e flag.
+set -e
+
+devpath=$1
+program=$2
+[ -n "$devpath" ]
+[ -n "$program" ]
+
+event_name=$(basename $devpath)
+is_event=
+case "$event_name" in
+    event*) is_event="yes" ;;
+    *);;
+esac
+[ "$is_event" = "yes" ]
+devpath="/sys$devpath"
+
+# A bunch of heuristic checks to determine that it is actually the controller
+# and neither a touchpad nor motion sensors which all have an event input
+# device and share the same udev attributes.
+cap_path=$devpath/device/capabilities
+[ -f $cap_path/abs ]
+[ -f $cap_path/ev ]
+[ -f $cap_path/ff ]
+[ -f $cap_path/key ]
+[ -f $cap_path/led ]
+[ -f $cap_path/msc ]
+[ -f $cap_path/rel ]
+[ -f $cap_path/snd ]
+[ -f $cap_path/sw ]
+[ "$(cat $cap_path/abs)" = "3003f" ]
+[ "$(cat $cap_path/ev)" = "1b" ]
+[ "$(cat $cap_path/ff)" = "0" ]
+[ "$(cat $cap_path/key)" = "7fdb000000000000 0 0 0 0" ]
+[ "$(cat $cap_path/led)" = "0" ]
+[ "$(cat $cap_path/msc)" = "10" ]
+[ "$(cat $cap_path/rel)" = "0" ]
+[ "$(cat $cap_path/snd)" = "0" ]
+[ "$(cat $cap_path/sw)" = "0" ]
+
+$program /dev/input/$event_name