hi,

 

i've been trying to get the SC16IS752/I2C UARTs working on opi-zero using DT Overlays. 

 

Here is my .dts:

 

/dts-v1/;
/plugin/;

/ {
   compatible = "allwinner,sun8i-h2", "allwinner,sun8i-h3";

        fragment@0 {
                target = <&i2c0>;
                __overlay__ {
                    #address-cells = <1>;
                    #size-cells = <0>;
                    status = "okay";

            sc16is752: sc16is752@4D {
                compatible = "nxp,sc16is752";
                reg = <0x4D>;
                clocks = <&sc16is752_clk>;
                interrupt-parent = <&pio>;
                interrupts = <0 10 2>;
                gpio-controller;
                #gpio-cells = <2>;

                sc16is752_clk: sc16is752_clk {
                    compatible = "fixed-clock";
                    #clock-cells = <0>;
                    clock-frequency = <14745600>;
                };
            };
        };
    };
};

it compiles  with no errors.

 

root@orangepizero:/boot/overlay-user# fdtdump ./sc16is752-i2c.dtbo
/dts-v1/;
// magic:               0xd00dfeed
// totalsize:           0x435 (1077)
// off_dt_struct:       0x38
// off_dt_strings:      0x36c
// off_mem_rsvmap:      0x28
// version:             17
// last_comp_version:   16
// boot_cpuid_phys:     0x0
// size_dt_strings:     0xc9
// size_dt_struct:      0x334

/ {
    compatible = "allwinner,sun8i-h2", "allwinner,sun8i-h3";
    fragment@0 {
        target = <0xdeadbeef>;
        __overlay__ {
            #address-cells = <0x00000001>;
            #size-cells = <0x00000000>;
            status = "okay";
            sc16is752@4D {
                compatible = "nxp,sc16is752";
                reg = <0x0000004d>;
                clocks = <0x00000001>;
                interrupt-parent = <0xdeadbeef>;
                interrupts = <0x00000000 0x0000000a 0x00000002>;
                gpio-controller;
                #gpio-cells = <0x00000002>;
                linux,phandle = <0x00000002>;
                phandle = <0x00000002>;
                sc16is752_clk {
                    compatible = "fixed-clock";
                    #clock-cells = <0x00000000>;
                    clock-frequency = <0x00e10000>;
                    linux,phandle = <0x00000001>;
                    phandle = <0x00000001>;
                };
            };
        };
    };
    __symbols__ {
        sc16is752 = "/fragment@0/__overlay__/sc16is752@4D";
        sc16is752_clk = "/fragment@0/__overlay__/sc16is752@4D/sc16is752_clk";
    };
    __fixups__ {
        i2c0 = "/fragment@0:target:0";
        pio = "/fragment@0/__overlay__/sc16is752@4D:interrupt-parent:0";
    };
    __local_fixups__ {
        fixup = "/fragment@0/__overlay__/sc16is752@4D:clocks:0";
    };
};

 

more info on the system:

 

root@orangepizero:~# uname -a
Linux orangepizero 4.14.12-sunxi #6 SMP Sat Jan 6 11:23:44 CET 2018 armv7l GNU/Linux

root@orangepizero:/boot# cat config-4.14.12-sunxi | grep "SC16IS"
CONFIG_SERIAL_SC16IS7XX_CORE=m
CONFIG_SERIAL_SC16IS7XX=m
CONFIG_SERIAL_SC16IS7XX_I2C=y
# CONFIG_SERIAL_SC16IS7XX_SPI is not set

root@orangepizero:/boot# lsmod
Module                  Size  Used by
sc16is7xx              20480  0
xradio_wlan            94208  1
mac80211              446464  1 xradio_wlan
cfg80211              376832  2 mac80211,xradio_wlan
sun8i_codec_analog     24576  0
rfkill                 20480  3 cfg80211
snd_soc_core          118784  1 sun8i_codec_analog
snd_pcm_dmaengine      16384  1 snd_soc_core
snd_pcm                65536  2 snd_pcm_dmaengine,snd_soc_core
snd_timer              24576  1 snd_pcm
snd                    45056  3 snd_timer,snd_soc_core,snd_pcm
soundcore              16384  1 snd
sun4i_gpadc_iio        16384  0
uio_pdrv_genirq        16384  0
uio                    16384  1 uio_pdrv_genirq
usb_f_acm              16384  1
u_serial               20480  3 usb_f_acm
g_serial               16384  0
libcomposite           40960  2 g_serial,usb_f_acm
ip_tables              20480  0
x_tables               20480  1 ip_tables
pwrseq_simple          16384  1

 

the problem is that the overlay is not loaded on boot-up:

 

Applying user provided DT overlay sc16is752-i2c.dtbo
failed on fdt_overlay_apply(): FDT_ERR_BADOVERLAY
Error applying DT overlays, restoring original DT

of course the chip is connected and visible on the I2C0 bus under 0x4D address.

what is wrong with the overlay?

 

 

regards

 

A.

4 hours ago, Artur said:

target = <0xdeadbeef>;

Where this comes from ?

It's probably that i2c overlays isn't loaded before your overlay ?

 

as far as I understood from https://www.raspberrypi.org/documentation/configuration/device-tree.md - this comes from unresolved at the compilation time symbol, which is later taken from the target

Did you tried to add the stuff in the main dtb (of course, after doing a backup) ?