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Table of Contents
GPIO bit-bang driver for Raspbian
Determine the running kernel and it's config on the Raspberry Pi target machine
uname -a
Linux pi3 3.12.28+ #709 PREEMPT Mon Sep 8 15:28:00 BST 2014 armv6l GNU/Linux
zgrep "* firmware as of" /usr/share/doc/raspberrypi-bootloader/changelog.Debian.gz | head -1 | awk '{ print $5 }'
53d1ae311226b5c
zcat /proc/config.gz > 53d1ae311226b5c.config
Examples
Linux pi3 3.6.11+ #538 PREEMPT Fri Aug 30 20:42:08 BST 2013 armv6l GNU/Linux d4f5315cfac4e Linux pi3 3.10.23+ #608 PREEMPT Mon Dec 9 21:11:23 GMT 2013 armv6l GNU/Linux 9d34d0475f9 Linux pi3 3.10.24+ #614 PREEMPT Thu Dec 19 20:38:42 GMT 2013 armv6l GNU/Linux c32bc633039cd9 Linux pi3 3.10.25+ #622 PREEMPT Fri Jan 3 18:41:00 GMT 2014 armv6l GNU/Linux 030082b403b Linux pi3 3.12.28+ #709 PREEMPT Mon Sep 8 15:28:00 BST 2014 armv6l GNU/Linux 53d1ae311226b5c
Determine the kernel hash for this firmware
wget -q https://raw.github.com/raspberrypi/firmware/53d1ae311226b5c/extra/git_hash -O /tmp/hash cat /tmp/hash 94a382fed1a5ec303eef9e1f3439df8f759ba60c
Examples
3.6.11+ d4f5315cfac4e 1587f775d0a3c437485262ba951afc5e30be69fa 3.10.23+ 9d34d0475f9 c15430e6a01e1332032d83f6484a866504e8ee97 3.10.24+ c32bc633039cd9 4bbea92eae6c0792e85a4ba079d367ac6aa77fb5 3.10.25+ 030082b403b 16eb921a96db3dc3555a65b53b99c15753e6b770 3.12.28+ 53d1ae311226b5c 94a382fed1a5ec303eef9e1f3439df8f759ba60c
On the build host fetch the kernel build tools
mkdir -p /embedded/rpi cd /embedded/rpi git clone git://github.com/raspberrypi/tools.git
Fetch the kernel source for the previously determined hash
cd /embedded/rpi rm -Rf /embedded/rpi/linux git clone https://github.com/raspberrypi/linux.git cd /embedded/rpi/linux/ git checkout 94a382fed1a5ec303eef9e1f3439df8f759ba60c git reset --hard
Prepare to build kernel and copy over configuration
make ARCH=arm mrproper scp pi@pi:53d1ae311226b5c.config .config
Build the kernel using the cross compiler tools
make ARCH=arm oldconfig make ARCH=arm CROSS_COMPILE=/embedded/rpi/tools/arm-bcm2708/arm-bcm2708hardfp-linux-gnueabi/bin/arm-bcm2708hardfp-linux-gnueabi- -j 8
Build the GPIO bit-bang module and copy to target machine
hg clone http://hg.kewl.org/pub/gpio-bb cd gpio-bb/raspbian make scp ../module/src/gpio-bb.ko pi@pi:
Install the module on the Raspberry Pi target machine (Eg. 3.12.28+)
mkdir -p /lib/modules/3.12.28+/kernel/local/ cp gpio-bb.ko /lib/modules/3.12.28+/kernel/local/ chown -R 0:0 /lib/modules/3.12.28+/kernel/local/ depmod -a
Load modules on target machine
/etc/modprobe.d/modprobe.conf: install gpio-bb modprobe --ignore-install gpio-bb && modprobe gpio-bb && mknod /dev/gpio-bb c 180 0
modprobe gpio-bb
