Hello,
I'm using an ARM Cortex A9 based platform. I have a minimal
3.14 port working (UART and Ethernet, loads a root file system
over NFS) using a board file.
I'm trying to convert the port to device tree, so that I can
(try to) push it upstream.
As I can't wrap my head around the concept, I'm trying to do
the conversion "one device at a time", starting with just the
UART, then Ethernet, then the clock tree, and that's basically
all I need to boot the board.
I started by enabling
CONFIG_ARM_APPENDED_DTB=y
CONFIG_ARM_ATAG_DTB_COMPAT=y
CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_FROM_BOOTLOADER=y
CONFIG_SERIAL_OF_PLATFORM=y
and wrote this dts:
/dts-v1/;
/ {
compatible = "sigma,tango4-soc";
#address-cells = <1>;
#size-cells = <1>;
soc {
compatible = "simple-bus";
#address-cells = <1>;
#size-cells = <1>;
ranges;
uart0: serial@10700 {
compatible = "ns16550a";
reg = <0x10700 0x100>;
interrupts = <1>;
clock-frequency = <7372800>;
reg-shift = <2>;
no-loopback-test;
#address-cells = <1>;
#size-cells = <1>;
};
};
};
and added "sigma,tango4-soc" to my struct machine_desc .dt_compat
Then I generated a kernel with appended DT using:
$ make dtbs
$ make -j2 zImage && cat arch/arm/boot/zImage arch/arm/boot/dts/tango.dtb >XXX
$ mv XXX arch/arm/boot/zImage && make uImage
Then I set a breakpoint in of_platform_serial_probe, hoping
to witness the miracle... and nothing. Looks like device is
never registered :-(
Can anyone point me where to look?
What did I do wrong?
Where does the kernel parse the appended DTB?
Is it setup_machine_fdt?
When/Where is the UART description in the device tree supposed
to be used to register the device?
Any help greatly appreciated!
Regards.
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