Javier Vela
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Hi,
I want to expand my NanoPi-NEO2 more uart ports through I2C, so I make a choice to use a sc16is750 module( just like sparkfun sc16is750 ).
Below is all of my system information:
pi@nanopineo2:~$ uname -a
Linux nanopineo2 5.4.20-sunxi64 #20.02.1 SMP Mon Feb 17 02:37:37 CET 2020 aarch64 aarch64 aarch64 GNU/Linux
First step ,I edit a device tree overlay for the sc16is750 named sc16is750-i2c.dts as below:
pi@nanopineo2:/boot/overlay-user$ sudo nano sc16is750-i2c.dts
/dts-v1/;
/plugin/;
/ {
compatible = "allwinner,sun4i-a10", "allwinner,sun7i-a20", "allwinner,sun8i-h3", "allwinner,sun50i-a64", "allwinner,sun50i-h5";
fragment@0 {
/* This fragment is required only if using interrupts */
target = <&pio>;
__overlay__ {
sc16is750_pin_irq: sc16is750_pin_irq {
pins = "PA17";
function = "irq";
bias-pull-up;
};
};
};
fragment@1 {
target = <&i2c1>;
__overlay__ {
#address-cells = <1>;
#size-cells = <0>;
sc16is750: sc16is750@4d {
compatible = "nxp,sc16is750";
reg = <0x4d>;
status = "okay";
clocks = <&sc16is750_clk>;
gpio-controller;
#gpio-cells = <3>;
/* Below are optional properties for supporting interrupts */
interrupt-controller;
#interrupt-cells = <3>;
interrupt-parent = <&pio>;
interrupts = <0 17 2>; /* PG11 IRQ_TYPE_EDGE_FALLING */
pinctrl-names = "default";
pinctrl-0 = <&sc16is750_pin_irq>;
sc16is750_clk: sc16is750_clk {
compatible = "fixed-clock";
#clock-cells = <0>;
clock-frequency = <14745600>;
};
};
};
};
__overrides__ {
int_pin = <&sc16is750>,"interrupts:0";
addr = <&sc16is750>,"reg:0";
};
};
Second step, I add the sc16is750-i2c.dts to my /boot/overlay-usr as below:
pi@nanopineo2:/boot/overlay-user$ sudo armbian-add-overlay sc16is750-i2c.dts
Compiling the overlay
Copying the compiled overlay file to /boot/overlay-user/
Reboot is required to apply the changes
Afterthen, I checked sc16is750-i2c.dtbo as below:
pi@nanopineo2:/boot/overlay-user$ fdtdump sc16is750-i2c.dtbo
**** fdtdump is a low-level debugging tool, not meant for general use.
**** If you want to decompile a dtb, you probably want
**** dtc -I dtb -O dts <filename>
/dts-v1/;
// magic: 0xd00dfeed
// totalsize: 0x5f8 (1528)
// off_dt_struct: 0x38
// off_dt_strings: 0x4d0
// off_mem_rsvmap: 0x28
// version: 17
// last_comp_version: 16
// boot_cpuid_phys: 0x0
// size_dt_strings: 0x128
// size_dt_struct: 0x498
/ {
compatible = "allwinner,sun4i-a10", "allwinner,sun7i-a20", "allwinner,sun8i-h3", "allwinner,sun50i-a64", "allwinner,sun50i-h5";
fragment@0 {
target = <0xffffffff>;
__overlay__ {
sc16is750_pin_irq {
pins = "PA17";
function = "irq";
bias-pull-up;
phandle = <0x00000002>;
};
};
};
fragment@1 {
target = <0xffffffff>;
__overlay__ {
#address-cells = <0x00000001>;
#size-cells = <0x00000000>;
sc16is750@4d {
compatible = "nxp,sc16is750";
reg = <0x0000004d>;
status = "okay";
clocks = <0x00000001>;
gpio-controller;
#gpio-cells = <0x00000003>;
interrupt-controller;
#interrupt-cells = <0x00000003>;
interrupt-parent = <0xffffffff>;
interrupts = <0x00000000 0x00000011 0x00000002>;
pinctrl-names = "default";
pinctrl-0 = <0x00000002>;
phandle = <0x00000003>;
sc16is750_clk {
compatible = "fixed-clock";
#clock-cells = <0x00000000>;
clock-frequency = <0x00e10000>;
phandle = <0x00000001>;
};
};
};
};
__symbols__ {
sc16is750_pin_irq = "/fragment@0/__overlay__/sc16is750_pin_irq";
sc16is750 = "/fragment@1/__overlay__/sc16is750@4d";
sc16is750_clk = "/fragment@1/__overlay__/sc16is750@4d/sc16is750_clk";
};
__fixups__ {
pio = "/fragment@0:target:0", "/fragment@1/__overlay__/sc16is750@4d:interrupt-parent:0";
i2c1 = "/fragment@1:target:0";
};
__local_fixups__ {
fragment@1 {
__overlay__ {
sc16is750@4d {
clocks = <0x00000000>;
pinctrl-0 = <0x00000000>;
};
};
};
};
};
After reboot, I check the tty devices:
pi@nanopineo2:~$ dmesg | grep tty
[ 2.056137] printk: console [ttyS0] disabled
[ 2.076722] 1c28000.serial: ttyS0 at MMIO 0x1c28000 (irq = 26, base_baud = 1500000) is a U6_16550A
[ 2.076773] printk: console [ttyS0] enabled
[ 2.098045] 1c28400.serial: ttyS1 at MMIO 0x1c28400 (irq = 27, base_baud = 1500000) is a U6_16550A
[ 2.119044] 1c28800.serial: ttyS2 at MMIO 0x1c28800 (irq = 28, base_baud = 1500000) is a U6_16550A
[ 2.142198] 1c28c00.serial: ttyS3 at MMIO 0x1c28c00 (irq = 29, base_baud = 1500000) is a U6_16550A
[ 5.873610] serial serial0: tty port ttySC0 registered
Also, I have check the i2c:
pi@nanopineo2:~$ sudo i2cdetect -y 1
[sudo] password for pi:
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- 3c -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- UU -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- 68 -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
my sc16is750 address:0x4d
Finally, I check the tty devices:
pi@nanopineo2:~$ ls -l /dev/ttyS*
crw------- 1 pi tty 4, 64 Mar 23 03:21 /dev/ttyS0
crw-rw---- 1 root dialout 4, 65 Mar 23 03:16 /dev/ttyS1
crw-rw---- 1 root dialout 4, 66 Mar 23 03:16 /dev/ttyS2
crw-rw---- 1 root dialout 4, 67 Mar 23 03:16 /dev/ttyS3
pi@nanopineo2:~$ cat /proc/tty/drivers
/dev/tty /dev/tty 5 0 system:/dev/tty
/dev/console /dev/console 5 1 system:console
/dev/ptmx /dev/ptmx 5 2 system
/dev/vc/0 /dev/vc/0 4 0 system:vtmaster
unknown /dev/ttySC 242 0-7 serial
g_serial /dev/ttyGS 245 0-3 serial
serial /dev/ttyS 4 64-67 serial
pty_slave /dev/pts 136 0-1048575 pty:slave
pty_master /dev/ptm 128 0-1048575 pty:master
unknown /dev/tty 4 1-63 console
So, My question is why I cannot find the /dev/ttySC0?
Anyone can give me some advice to resolve the problem.
Thanks.
