# Create a temp directory for our work
mkdir ~/c720patch
cd ~/c720patch

# Determine kernel version (with and without Ubuntu-specific suffix)
mykern=${1:-$(uname -r)}
mykernsrc=$(uname -v | cut -d' ' -f4)

sudo apt-get update

# Install necessary deps to build a kernel
sudo apt-get build-dep -y --no-install-recommends linux

# Grab Ubuntu kernel source
sudo apt-get install linux-headers-$mykern
apt-get source linux=$mykernsrc
cd linux*

# Use Benson Leung's post-Pixel Chromebook patches:
# https://patchwork.kernel.org/bundle/bleung/chromeos-laptop-deferring-and-haswell/
for patch in 3078491 3078481 3074391 3074441 3074421 3074401 3074431 3074411; do
  wget -O - https://patchwork.kernel.org/patch/$patch/raw/ | sed 's/x86/chrome/g' | patch -p1
done

# Need this
cp /usr/src/linux-headers-$mykern/Module.symvers .

# Prep tree
cp /boot/config-$mykern ./.config
echo "CONFIG_CHROMEOS_LAPTOP=m" >> ./.config
make oldconfig
make prepare
make modules_prepare

# Build only the needed directories
make SUBDIRS=drivers/platform/chrome modules
make SUBDIRS=drivers/i2c/busses modules

# switch to using our new chromeos_laptop.ko module
# preserve old as .orig
sudo mv /lib/modules/$mykern/kernel/drivers/platform/chrome/chromeos_laptop.ko /lib/modules/$mykern/kernel/drivers/platform/x86/chromeos_laptop.ko.orig
sudo cp drivers/platform/chrome/chromeos_laptop.ko /lib/modules/$mykern/kernel/drivers/platform/x86/

# switch to using our new designware i2c modules
# preserve old as .orig
sudo mv /lib/modules/$mykern/kernel/drivers/i2c/busses/i2c-designware-core.ko /lib/modules/$mykern/kernel/drivers/i2c/busses/i2c-designware-core.ko.orig
sudo mv /lib/modules/$mykern/kernel/drivers/i2c/busses/i2c-designware-pci.ko /lib/modules/$mykern/kernel/drivers/i2c/busses/i2c-designware-pci.ko.orig
#sudo mv /lib/modules/$mykern/kernel/drivers/i2c/busses/i2c-designware-platform.ko /lib/modules/$mykern/kernel/drivers/i2c/busses/i2c-designware-platform.ko.orig
sudo cp drivers/i2c/busses/i2c-designware-*.ko /lib/modules/$mykern/kernel/drivers/i2c/busses/
sudo depmod -a $mykern
echo "Finished building Chromebook modules in $tempbuild. Reboot to use them."