Initial commit

Config.in

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+source "$BR2_EXTERNAL_MT32_PI_PATH/package/libmt32emu/Config.in"
+source "$BR2_EXTERNAL_MT32_PI_PATH/package/mt32d/Config.in"

README.md

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+# mt32-pi
+
+A [Buildroot](https://buildroot.org) external tree which which turns your
+Raspberry Pi 2 into a dedicated
+[Roland MT-32](https://en.wikipedia.org/wiki/Roland_MT-32) emulator based on
+[MUNT/libmt32em](https://github.com/munt/munt).
+
+The aim is to have the Raspberry Pi boot into a working state in about 5
+seconds.
+
+## How to use it
+
+  * Check out this repo.
+  * Copy `MT32_CONTROL.ROM` and `MT32_PCM.ROM` to the `mt32-roms` folder
+    (you need to source these copyrighted ROMs yourself).
+  * Download and extract Buildroot 2016.11 or later.
+  * Build the system (this will take a long time):
+
+        cd /path/to/buildroot
+        make BR2_EXTERNAL=/path/to/this/repo raspberrypi2_defconfig
+        make
+  * After a successful build, an SD card image is located in
+    `output/images/sdcard.img`.
+  * Copy the image onto an SD card with `dd` (use the correct argument for
+    the device representing your SD card reader):
+
+        sudo dd if=output/images/sdcard.img of=/dev/sdc bs=1M
+        sync
+  * Place the SD card into the Raspberry Pi 2, attach a USB MIDI cable,
+    and enjoy!
+
+## TODO
+
+  * There is some kind of delay in the handling of MIDI messages when many
+    messages arrive at once (more complex songs). Need to figure out what this
+    is being caused by (slow Pi USB MIDI? Would a GPIO MIDI interface be
+    better? Threading problem with `mt32d`?).
+  * Hardcoded to use (poor) internal sound and first USB MIDI device. Need to
+    script hotplugging things properly and select appropriate devices.
+  * Maybe try to use `PREEMPT_RT` kernel patch to see if it helps to get the
+    latency of `mt32d` down as low as possible with various audio devices.
+    N.B.: USB audio devices can achieve lower latency and superior sound
+    quality to the internal audio.
+  * Provide configurations for external LCD screens such as 3.2" touchscreens
+    and various character displays in order to allow the virtual MT-32 to
+    output messages and be controlled.
+  * Reduce initial build time and image size by disabling unnecessary kernel
+    modules.
+  * In relation to above, reduce startup time. There's a 2 second `sleep` while
+    we wait for the MIDI interfaces to come up before invoking `aconnect`; this
+    needs to go away. A 'release' build could also remove network/SSH as this
+    increases startup time. 

board/raspberrypi2/genimage-raspberrypi.cfg

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+image boot.vfat {
+  vfat {
+    files = {
+      "bcm2708-rpi-b.dtb",
+      "bcm2708-rpi-b-plus.dtb",
+      "bcm2708-rpi-cm.dtb",
+      "rpi-firmware/bootcode.bin",
+      "rpi-firmware/cmdline.txt",
+      "rpi-firmware/config.txt",
+      "rpi-firmware/fixup.dat",
+      "rpi-firmware/start.elf",
+      "kernel-marked/zImage"
+    }
+  }
+  size = 32M
+}
+
+image sdcard.img {
+  hdimage {
+  }
+
+  partition boot {
+    partition-type = 0xC
+    bootable = "true"
+    image = "boot.vfat"
+  }
+
+  partition rootfs {
+    partition-type = 0x83
+    image = "rootfs.ext4"
+  }
+}

board/raspberrypi2/genimage-raspberrypi0.cfg

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+image boot.vfat {
+  vfat {
+    files = {
+      "bcm2708-rpi-b-plus.dtb",
+      "rpi-firmware/bootcode.bin",
+      "rpi-firmware/cmdline.txt",
+      "rpi-firmware/config.txt",
+      "rpi-firmware/fixup.dat",
+      "rpi-firmware/start.elf",
+      "kernel-marked/zImage"
+    }
+  }
+  size = 32M
+}
+
+image sdcard.img {
+  hdimage {
+  }
+
+  partition boot {
+    partition-type = 0xC
+    bootable = "true"
+    image = "boot.vfat"
+  }
+
+  partition rootfs {
+    partition-type = 0x83
+    image = "rootfs.ext4"
+  }
+}

board/raspberrypi2/genimage-raspberrypi2.cfg

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+image boot.vfat {
+  vfat {
+    files = {
+      "bcm2709-rpi-2-b.dtb",
+      "rpi-firmware/bootcode.bin",
+      "rpi-firmware/cmdline.txt",
+      "rpi-firmware/config.txt",
+      "rpi-firmware/fixup.dat",
+      "rpi-firmware/start.elf",
+      "kernel-marked/zImage"
+    }
+  }
+  size = 32M
+}
+
+image sdcard.img {
+  hdimage {
+  }
+
+  partition boot {
+    partition-type = 0xC
+    bootable = "true"
+    image = "boot.vfat"
+  }
+
+  partition rootfs {
+    partition-type = 0x83
+    image = "rootfs.ext4"
+  }
+}

board/raspberrypi2/genimage-raspberrypi3.cfg

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+image boot.vfat {
+  vfat {
+    files = {
+      "bcm2710-rpi-3-b.dtb",
+      "rpi-firmware/bootcode.bin",
+      "rpi-firmware/cmdline.txt",
+      "rpi-firmware/config.txt",
+      "rpi-firmware/fixup.dat",
+      "rpi-firmware/start.elf",
+      "rpi-firmware/overlays",
+      "kernel-marked/zImage"
+    }
+  }
+  size = 32M
+}
+
+image sdcard.img {
+  hdimage {
+  }
+
+  partition boot {
+    partition-type = 0xC
+    bootable = "true"
+    image = "boot.vfat"
+  }
+
+  partition rootfs {
+    partition-type = 0x83
+    image = "rootfs.ext4"
+  }
+}

board/raspberrypi2/post-build.sh

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+#!/bin/sh
+
+set -u
+set -e
+
+# Add a console on tty1
+if [ -e ${TARGET_DIR}/etc/inittab ]; then
+    grep -qE '^tty1::' ${TARGET_DIR}/etc/inittab || \
+	sed -i '/GENERIC_SERIAL/a\
+tty1::respawn:/sbin/getty -L  tty1 0 vt100 # HDMI console' ${TARGET_DIR}/etc/inittab
+fi
+
+# Override Raspberry Pi config.txt
+echo -n "Copying Raspberry Pi boot config..."
+cp ${BR2_EXTERNAL_MT32_PI_PATH}/rpi-bootconfig.txt ${BINARIES_DIR}/rpi-firmware/config.txt
+echo " OK!"
+
+# Copy MT-32 ROMs into place
+echo -n "Copying MT-32 ROMs..."
+if [ ! -f ${BR2_EXTERNAL_MT32_PI_PATH}/mt32-roms/MT32_CONTROL.ROM ]; then
+    echo "\nMT32_CONTROL.ROM is missing. Please place it into the mt32-roms directory."
+    exit 1
+fi
+
+if [ ! -f ${BR2_EXTERNAL_MT32_PI_PATH}/mt32-roms/MT32_PCM.ROM ]; then
+    echo "\nMT32_PCM.ROM is missing. Please place it into the mt32-roms directory."
+    exit 1
+fi
+
+mkdir -p ${TARGET_DIR}/usr/share/mt32-rom-data
+cp ${BR2_EXTERNAL_MT32_PI_PATH}/mt32-roms/*.ROM ${TARGET_DIR}/usr/share/mt32-rom-data/
+echo " OK!"

board/raspberrypi2/post-image.sh

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+#!/bin/sh
+
+BOARD_DIR="$(dirname $0)"
+BOARD_NAME="$(basename ${BOARD_DIR})"
+GENIMAGE_CFG="${BOARD_DIR}/genimage-${BOARD_NAME}.cfg"
+GENIMAGE_TMP="${BUILD_DIR}/genimage.tmp"
+
+case "${2}" in
+	--add-pi3-miniuart-bt-overlay)
+	if ! grep -qE '^dtoverlay=' "${BINARIES_DIR}/rpi-firmware/config.txt"; then
+		echo "Adding 'dtoverlay=pi3-miniuart-bt' to config.txt (fixes ttyAMA0 serial console)."
+		cat << __EOF__ >> "${BINARIES_DIR}/rpi-firmware/config.txt"
+
+# fixes rpi3 ttyAMA0 serial console
+dtoverlay=pi3-miniuart-bt
+__EOF__
+	fi
+	;;
+esac
+
+# Mark the kernel as DT-enabled
+mkdir -p "${BINARIES_DIR}/kernel-marked"
+${HOST_DIR}/usr/bin/mkknlimg "${BINARIES_DIR}/zImage" \
+	"${BINARIES_DIR}/kernel-marked/zImage"
+
+rm -rf "${GENIMAGE_TMP}"
+
+genimage                           \
+	--rootpath "${TARGET_DIR}"     \
+	--tmppath "${GENIMAGE_TMP}"    \
+	--inputpath "${BINARIES_DIR}"  \
+	--outputpath "${BINARIES_DIR}" \
+	--config "${GENIMAGE_CFG}"
+
+exit $?

board/raspberrypi2/readme.txt

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+Raspberry Pi
+
+Intro
+=====
+
+These instructions apply to all models of the Raspberry Pi:
+  - the original models A and B,
+  - the "enhanced" models A+ and B+,
+  - the model B2 (aka Raspberry Pi 2)
+  - the model B3 (aka Raspberry Pi 3).
+
+How to build it
+===============
+
+Configure Buildroot
+-------------------
+
+There are two RaspberryPi defconfig files in Buildroot, one for each
+major variant, which you should base your work on:
+
+For models A, B, A+ or B+:
+
+  $ make raspberrypi_defconfig
+
+For model 2 B:
+
+  $ make raspberrypi2_defconfig
+
+For model 3 B:
+
+  $ make raspberrypi3_defconfig
+
+Build the rootfs
+----------------
+
+Note: you will need to have access to the network, since Buildroot will
+download the packages' sources.
+
+You may now build your rootfs with:
+
+  $ make
+
+(This may take a while, consider getting yourself a coffee ;-) )
+
+Result of the build
+-------------------
+
+After building, you should obtain this tree:
+
+    output/images/
+    +-- bcm2708-rpi-b.dtb           [1]
+    +-- bcm2708-rpi-b-plus.dtb      [1]
+    +-- bcm2709-rpi-2-b.dtb         [1]
+    +-- bcm2710-rpi-3-b.dtb         [1]
+    +-- boot.vfat
+    +-- kernel-marked/zImage        [2]
+    +-- rootfs.ext4
+    +-- rpi-firmware/
+    |   +-- bootcode.bin
+    |   +-- cmdline.txt
+    |   +-- config.txt
+    |   +-- fixup.dat
+    |   +-- start.elf
+    |   `-- overlays/               [3]
+    +-- sdcard.img
+    `-- zImage
+
+[1] Not all of them will be present, depending on the RaspberryPi
+    model you are using.
+
+[2] This is the mkknlimg DT-marked kernel.
+
+[3] Only for the Raspberry Pi 3 Model (overlay pi3-miniuart-bt is needed
+    to enable the RPi3 serial console otherwise occupied by the bluetooth
+    chip). Alternative would be to disable the serial console in cmdline.txt
+    and /etc/inittab.
+
+How to write the SD card
+========================
+
+Once the build process is finished you will have an image called "sdcard.img"
+in the output/images/ directory.
+
+Copy the bootable "sdcard.img" onto an SD card with "dd":
+
+  $ sudo dd if=output/images/sdcard.img of=/dev/sdX
+
+Insert the SDcard into your Raspberry Pi, and power it up. Your new system
+should come up now and start two consoles: one on the serial port on
+the P1 header, one on the HDMI output where you can login using a USB
+keyboard.

board/raspberrypi2/users.txt

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+pi 8000 wheel -1 =pi /home/pi /bin/sh - Default user

configs/raspberrypi2_defconfig

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+BR2_arm=y
+BR2_cortex_a7=y
+BR2_ARM_FPU_NEON_VFPV4=y
+BR2_CCACHE=y
+BR2_OPTIMIZE_3=y
+BR2_TOOLCHAIN_BUILDROOT_GLIBC=y
+BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_4_4=y
+BR2_EXTRA_GCC_CONFIG_OPTIONS="--with-float=hard"
+BR2_TOOLCHAIN_BUILDROOT_CXX=y
+BR2_TARGET_OPTIMIZATION="-pipe -mfpu=vfpv4"
+BR2_TARGET_GENERIC_HOSTNAME="mt32-pi"
+BR2_TARGET_GENERIC_ISSUE="Welcome to MT-32 Pi!"
+BR2_GENERATE_LOCALE="en_US"
+BR2_ROOTFS_USERS_TABLES="${BR2_EXTERNAL_MT32_PI_PATH}/board/raspberrypi2/users.txt"
+BR2_ROOTFS_OVERLAY="${BR2_EXTERNAL_MT32_PI_PATH}/fsoverlay"
+BR2_ROOTFS_POST_BUILD_SCRIPT="${BR2_EXTERNAL_MT32_PI_PATH}/board/raspberrypi2/post-build.sh"
+BR2_ROOTFS_POST_IMAGE_SCRIPT="${BR2_EXTERNAL_MT32_PI_PATH}/board/raspberrypi2/post-image.sh"
+BR2_LINUX_KERNEL=y
+BR2_LINUX_KERNEL_CUSTOM_GIT=y
+BR2_LINUX_KERNEL_CUSTOM_REPO_URL="https://github.com/raspberrypi/linux.git"
+BR2_LINUX_KERNEL_CUSTOM_REPO_VERSION="raspberrypi-kernel_1.20161020-1"
+BR2_LINUX_KERNEL_PATCH="${BR2_EXTERNAL_MT32_PI_PATH}/board/raspberrypi2/patches/"
+BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
+BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="${BR2_EXTERNAL_MT32_PI_PATH}/board/raspberrypi2/kernel.config"
+BR2_LINUX_KERNEL_DTS_SUPPORT=y
+BR2_LINUX_KERNEL_INTREE_DTS_NAME="bcm2709-rpi-2-b"
+BR2_PACKAGE_ALSA_UTILS=y
+BR2_PACKAGE_ALSA_UTILS_ALSACONF=y
+BR2_PACKAGE_ALSA_UTILS_ACONNECT=y
+BR2_PACKAGE_ALSA_UTILS_AMIDI=y
+BR2_PACKAGE_ALSA_UTILS_AMIXER=y
+BR2_PACKAGE_ALSA_UTILS_APLAY=y
+BR2_PACKAGE_ALSA_UTILS_APLAYMIDI=y
+BR2_PACKAGE_ALSA_UTILS_ASEQDUMP=y
+BR2_PACKAGE_ALSA_UTILS_SPEAKER_TEST=y
+BR2_PACKAGE_RPI_FIRMWARE=y
+# BR2_PACKAGE_RPI_FIRMWARE_INSTALL_DTB_OVERLAYS is not set
+BR2_PACKAGE_OPENSSH=y
+BR2_TARGET_ROOTFS_EXT2=y
+BR2_TARGET_ROOTFS_EXT2_4=y
+# BR2_TARGET_ROOTFS_TAR is not set
+BR2_PACKAGE_HOST_DOSFSTOOLS=y
+BR2_PACKAGE_HOST_GENIMAGE=y
+BR2_PACKAGE_HOST_MTOOLS=y
+BR2_PACKAGE_LIBMT32EMU=y
+BR2_PACKAGE_MT32D=y

external.desc

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+name: MT32_PI
+desc: An embedded, standalone Roland MT-32 emulator for the Raspberry Pi 2 based on MUNT.

external.mk

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+include $(sort $(wildcard $(BR2_EXTERNAL_MT32_PI_PATH)/package/*/*.mk))

fsoverlay/etc/init.d/S15governor

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+#!/bin/sh
+
+for cpu in /sys/devices/system/cpu/cpu[0-9]*
+do
+    echo -n performance | tee $cpu/cpufreq/scaling_governor >/dev/null
+done

fsoverlay/etc/init.d/S15modules

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+#!/bin/sh
+
+modprobe snd-seq
+modprobe snd-usb-audio index=1
+modprobe snd-bcm2835

fsoverlay/etc/init.d/S16switch-headphone

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+#!/bin/sh
+
+amixer cset numid=3 1

fsoverlay/etc/init.d/S17mt32d

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+#!/bin/sh
+
+# External USB soundcard is happy with lower buffer of 5 or so,
+# but internal Pi sound device doesn't cope too well
+mt32d -i 10 &
+
+# This needs replacing with some kind of hotplug event handler to
+# attach MIDI devices to MUNT
+sleep 2
+aconnect 20:0 128:0

mt32-roms/README.md

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+Please place your MT32_CONTROL.ROM and MT32_PCM.ROM files here.

package/libmt32emu/Config.in

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+config BR2_PACKAGE_LIBMT32EMU
+	bool "libmt32emu"
+	help
+	  C/C++ library to emulate (approximately) the Roland MT-32, CM-32L and LAPC-I synthesiser modules.
+
+	  http://github.com/munt/munt

package/libmt32emu/libmt32.mk

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+################################################################################
+#
+# libmt32emu
+#
+################################################################################
+
+LIBMT32EMU_VERSION = 2.0.1
+LIBMT32EMU_SOURCE = libmt32emu_2_0_1.tar.gz 
+LIBMT32EMU_SITE = https://github.com/munt/munt/archive
+LIBMT32EMU_INSTALL_STAGING = YES
+LIBMT32EMU_CONF_OPTS = -DCMAKE_VERBOSE_MAKEFILE=TRUE -DCMAKE_BUILD_TYPE=Release -Dmunt_WITH_MT32EMU_QT=FALSE -Dmunt_WITH_MT32EMU_SMF2WAV=FALSE
+
+$(eval $(cmake-package))

package/mt32d/Config.in

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+config BR2_PACKAGE_MT32D
+	bool "mt32d"
+	depends on BR2_PACKAGE_LIBMT32EMU
+	help
+	  Daemon to emulate a Roland MT-32 synthesizer module.
+
+	  http://github.com/munt/munt

package/mt32d/mt32d.mk

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+################################################################################
+#
+# mt32d
+#
+################################################################################
+
+MT32D_VERSION = 2.0.1
+MT32D_SOURCE = libmt32emu_2_0_1.tar.gz 
+MT32D_SITE = https://github.com/munt/munt/archive
+MT32D_INSTALL_STAGING = YES
+MT32D_DEPENDENCIES = libmt32emu
+
+define MT32D_BUILD_CMDS
+	$(MAKE) $(TARGET_CONFIGURE_OPTS) CXXFLAGS+="-DANALOG_MODE=2" -C $(@D)/mt32emu_alsadrv mt32d
+endef
+
+define MT32D_INSTALL_STAGING_CMDS
+	$(INSTALL) -D -m 0755 $(@D)/mt32emu_alsadrv/mt32d $(TARGET_DIR)/usr/bin/mt32d
+endef
+
+define MT32D_INSTALL_TARGET_CMDS
+	$(INSTALL) -D -m 0755 $(@D)/mt32emu_alsadrv/mt32d $(TARGET_DIR)/usr/bin/mt32d
+endef
+
+$(eval $(generic-package))

rpi-bootconfig.txt

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+kernel=zImage
+disable_overscan=1
+disable_splash=1
+boot_delay=0
+dtparam=audio=on
+dtparam=spi=on
+
+arm_freq=900
+arm_freq_min=300
+
+gpu_mem=64
+sdram_freq=500
+core_freq=500
+over_voltage=2
+temp_limit=80
+initial_turbo=30