ttySCx missing in /dev ---> kernel: overlays: Fix sc16is75x overlays w.r.t. serdev

[Louro]

Hey

Looks like after upgrading tho 5.4.72 and newest 73 the /dev/ttySCx is missing

uname -na
Linux CODESYS 5.4.73-v7+ #1360 SMP Thu Oct 29 15:53:18 GMT 2020 armv7l GNU/Linux

$ sudo 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 239 0-7 serial
acm /dev/ttyACM 166 0-255 serial
ttyAMA /dev/ttyAMA 204 64-77 serial
ttyprintk /dev/ttyprintk 5 3 console
serial /dev/ttyS 4 64 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

$ ls /dev
autofs cuse gpiochip2 initctl loop5 mmcblk0p1 ram1 ram4 rtc stdout tty15 tty23 tty31 tty4 tty48 tty56 tty7 urandom vcs3 vcsa5 vcsu5 video16
block disk gpiochip3 input loop6 mmcblk0p2 ram10 ram5 rtc0 tty tty16 tty24 tty32 tty40 tty49 tty57 tty8 usb vcs4 vcsa6 vcsu6 watchdog
btrfs-control dma_heap gpiomem kmsg loop7 mqueue ram11 ram6 serial tty0 tty17 tty25 tty33 tty41 tty5 tty58 tty9 v4l vcs5 vcsm vhci watchdog0
bus fb0 hidraw0 log loop-control net ram12 ram7 serial0 tty1 tty18 tty26 tty34 tty42 tty50 tty59 ttyACM0 vchiq vcs6 vcsm-cma video10 zero
cachefiles fd hwrng loop0 mapper null ram13 ram8 serial1 tty10 tty19 tty27 tty35 tty43 tty51 tty6 ttyAMA0 vcio vcsa vcsu video11
char full i2c-0 loop1 media0 ppp ram14 ram9 shm tty11 tty2 tty28 tty36 tty44 tty52 tty60 ttyprintk vc-mem vcsa1 vcsu1 video12
char_dev fuse i2c-1 loop2 media1 ptmx ram15 random snd tty12 tty20 tty29 tty37 tty45 tty53 tty61 ttyS0 vcs vcsa2 vcsu2 video13
console gpiochip0 i2c-10 loop3 mem pts ram2 raw stderr tty13 tty21 tty3 tty38 tty46 tty54 tty62 uhid vcs1 vcsa3 vcsu3 video14
cpu_dma_latency gpiochip1 i2c-11 loop4 mmcblk0 ram0 ram3 rfkill stdin tty14 tty22 tty30 tty39 tty47 tty55 tty63 uinput vcs2 vcsa4 vcsu4 video15

dmesg | grep tty
[ 0.000864] printk: console [tty0] enabled
[ 2.769802] 3f201000.serial: ttyAMA0 at MMIO 0x3f201000 (irq = 81, base_baud = 0) is a PL011 rev2
[ 2.777032] 3f215040.serial: ttyS0 at MMIO 0x0 (irq = 53, base_baud = 62500000) is a 16550
[ 9.331081] cdc_acm 1-1.2:1.0: ttyACM0: USB ACM device
[ 10.098718] serial serial0: tty port ttySC0 registered
[ 10.099217] serial serial1: tty port ttySC1 registered

[Louro]

Maybe I managed to fix it, just need to tested with RS485 bus.

in /boot/config.txt i have the wrong overlay file, was using sc16is752-spi0-ce1.dtbo and changing the config.txt to sc16is752-spi0 it shows now the serial ports

This a specific configuration for Andino IO board.

SPI on

dtoverlay=spi0-cs,cs0_pin=8,cs1_pin=7
dtparam=spi=on

2. UART

/dev/ttySC0 = RS485

/dev/ttySC1 = RS232

dtoverlay=sc16is752-spi0,int_pin=24

[pelwell]

You had me worried there for a moment, but the overlay has been adjusted to work with serdev support enabled (by moving the clock node out of the sc16is752@0 node).

[Louro]

I have tested now with RS485 and its NOT working.

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 239 0-7 serial
usbserial /dev/ttyUSB 188 0-511 serial
ttyAMA /dev/ttyAMA 204 64-77 serial
ttyprintk /dev/ttyprintk 5 3 console
serial /dev/ttyS 4 64 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

Not sure if the "unknown" has something todo with it.

I have added a USB to RS485 adapter and that works with the RS485 network I was using before with SC16IS752.

Is there a new overlay file we need to use to get this fixed?

[stevenmacedo]

@Louro i facing the same issue, do you have solution?

thank you.