board: Add PowerPC mac99

PowerPC kernel developers were after a userspace for testing 32-bit
powerpc kernels. This machine both suits that requirement and has
support in qemu. It's also a fairly common piece of 32-bit ppc hardware.

Signed-off-by: Joel Stanley <joel@jms.id.au>
Tested-by: Daniel Axtens <dja@axtens.net>
[Peter: lock kernel/headers to 5.2.4]
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

DEVELOPERS

@@ -1149,6 +1149,8 @@ N:	Joel Stanley <joel@jms.id.au>
 F:	package/pdbg/
 F:	board/qemu/ppc64le-pseries/
 F:	configs/qemu_ppc64le_pseries_defconfig
+F:	board/qemu/ppc-mac99/
+F:	configs/qemu_ppc_mac99_defconfig
 
 N:	Johan Derycke <johanderycke@gmail.com>
 F:	package/python-libconfig/

board/qemu/ppc-mac99/linux.fragment

@@ -0,0 +1,3 @@
+CONFIG_SERIAL_PMACZILOG=y
+CONFIG_SERIAL_PMACZILOG_TTYS=y
+CONFIG_SERIAL_PMACZILOG_CONSOLE=y

board/qemu/ppc-mac99/readme.txt

@@ -0,0 +1,5 @@
+Run the emulation with:
+
+  qemu-system-ppc -nographic -vga none -M mac99 -cpu g4 -m 1G -kernel output/images/vmlinux -drive file=output/images/rootfs.ext2,format=raw -net nic,model=sungem -net user -append "root=/dev/sda"
+
+Tested with QEMU 3.1.0

configs/qemu_ppc_mac99_defconfig

@@ -0,0 +1,14 @@
+BR2_powerpc=y
+BR2_powerpc_7400=y
+BR2_TARGET_GENERIC_GETTY_PORT="ttyS0"
+BR2_SYSTEM_DHCP="eth0"
+BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_5_2=y
+BR2_LINUX_KERNEL=y
+BR2_LINUX_KERNEL_CUSTOM_VERSION=y
+BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="5.2.4"
+BR2_LINUX_KERNEL_DEFCONFIG="pmac32"
+BR2_LINUX_KERNEL_CONFIG_FRAGMENT_FILES="board/qemu/ppc-mac99/linux.fragment"
+BR2_LINUX_KERNEL_VMLINUX=y
+BR2_TARGET_ROOTFS_CPIO=y
+BR2_TARGET_ROOTFS_EXT2=y
+# BR2_TARGET_ROOTFS_TAR is not set