Mainline Linux Khadas MCU driver

narmstrong · April 6, 2020, 9:59am

Hi Guys,

I started writing a proper driver for the Khadas MCU present on the VIM2 rev 13, VIM3, VIM3L and Edge boards :

The main feature is to have FAN control, this adds it as hwmon device and cooling-devices added the the cpu thermal zone as active cooling devices in addition to the CPUs DVFS in passive & hot.
It also adds a power-off driver, and an nvmem driver for the USER memory.

I plan to send it to the upstream mailing-lists this week, but I’d like to have some tests and feedbacks !

I haven’t added it to the VIM2 DT since I don’t know how to handle the second revision of the board upstream, but it should work just fine.

Cc: @hyphop @Gouwa

Neil

hyphop · April 6, 2020, 10:24am

big tnx!!! for good news !

Gouwa · April 6, 2020, 12:11pm

The HW ID is different between V12 and V13/14:

V12:

V13/14:

narmstrong · April 7, 2020, 8:45am

Thanks @Gouwa, it will help for U-Boot, but for Linux side, should I add a separate upstream khadas-vim2-v14.dts selected by U-Boot with this HW_ID ?

Concerning the MCU, I was unable to change the USER bytes, is there a specific sequence to change them ? I only exposed the USER bytes in the nvmem driver, but I could expose more fields like the MAC, and USID.

Gouwa · April 7, 2020, 10:04am

@numbqq Wes should be have a solution for reference, right?

numbqq will assist you on this.

numbqq · April 7, 2020, 11:38am

We change the dts dynamicly before booting linux.

github.com

khadas/fenix/blob/master/config/bootscripts/aml_boot.ini#L150


						if test -e ${dev} ${dev_num}:${distro_bootpart} ${mark_prefix}.next; then
							echo "Booting mainline kernel...";
							setenv condev "console=ttyAML0,115200n8 console=tty0 no_console_suspend consoleblank=0";


							# Setup dtb for different HW version
							fdt addr ${dtb_loadaddr};
							fdt resize 65536;


							if test "X${hwver}" = "XVIM1.V14"; then
								fdt set /soc/bus@c1100000/i2c@87c0/khadas-mcu@18 hwver "VIM1.V14";
							else if test "X${hwver}" = "XVIM2.V14"; then
								fdt set /soc/bus@c1100000/i2c@87c0/khadas-mcu@18 hwver "VIM2.V14";
								fdt set /gpio-fan status "disabled";
								fdt set /fan status "disabled";
							else if test "X${hwver}" = "XVIM3.V11" || test "X${hwver}" = "XVIM3.V12"; then
								fdt set /soc/bus@ff800000/i2c@5000/khadas-mcu@18 hwver ${hwver};
								kbi init;
								kbi portmode r;


								fdt get value usb2_phy0 /soc/bus@ff600000/phy@36000 phandle;
								fdt get value usb2_phy1 /soc/bus@ff600000/phy@3a000 phandle;

But for mainline kernel, maybe a separate dts is needed.

narmstrong · April 7, 2020, 4:08pm

OK, I will add a separate DT file to be selected by the bootloader.

@hyphop did you have time to test the driver ?

numbqq · April 8, 2020, 2:57am

Hello Neil,

We will test this driver, thank you!

In order to access the USER data registers, you need to check the user password, default is khadas.

i2cset -f -y 2 0x18 0x81 0x1        // check password start
i2cset -f -y 2 0x18 0x83 0x4B     // password[0] = 'k'
i2cset -f -y 2 0x18 0x83 0x68     // password[1] = 'h'
i2cset -f -y 2 0x18 0x83 0x61     // password[2] = 'a'
i2cset -f -y 2 0x18 0x83 0x64     // password[3] = 'd'
i2cset -f -y 2 0x18 0x83 0x61     // password[4] = 'a'
i2cset -f -y 2 0x18 0x83 0x73     // password[5] = 's'
i2cset -f -y 2 0x18 0x81 0x0       // check password done

After this you can write/read the USER registers.

Note: If you change the default user password, you need to remenber the new one you set.

narmstrong · April 8, 2020, 7:56am

Right I missed this, I’ll add a way to check the password in the nvmem driver.

narmstrong · June 25, 2020, 8:25am

The MCU driver has been accepted for upstream: https://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd.git/log/?h=for-mfd-next