Hi all, I have a raspberry pi 3B, running kernel 5.10.17. On the i2c bus, I've added a rx8900 rtc chip. I would like to use this chip, but I fail to create a /dev/rtc for it. I have checked the kernel version: # uname -a Linux raspberrypi 5.10.17-v7+ #1421 SMP Thu May 27 13:59:01 BST 2021 armv7l GNU/Linux I've downloaded the rtc driver for this version of the kernel from here: https://github.com/raspberrypi/linux/blob/rpi-5.10.y/drivers/rtc/rtc-rv8803.c And compiled the driver with this makefile [1, see below] and installed the resulting rtc-rv8803.ko here: $ modinfo /usr/lib/modules/5.10.17-v7+/kernel/drivers/rtc/rtc-rv8803.ko filename: /usr/lib/modules/5.10.17-v7+/kernel/drivers/rtc/rtc-rv8803.ko license: GPL v2 description: Micro Crystal RV8803 RTC driver author: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx> srcversion: 0067552CB786360DEA9CADB alias: i2c:rx8900 alias: i2c:rx8803 alias: i2c:rv8803 alias: of:N*T*Cepson,rx8900C* alias: of:N*T*Cepson,rx8900 alias: of:N*T*Cepson,rx8803C* alias: of:N*T*Cepson,rx8803 alias: of:N*T*Cmicrocrystal,rv8803C* alias: of:N*T*Cmicrocrystal,rv8803 depends: name: rtc_rv8803 vermagic: 5.10.17-v7+ SMP mod_unload modversions ARMv7 p2v8 Next I do the following steps to load the module: # modprobe i2c:rx8900 [ 130.591843] rtc_rv8803: loading out-of-tree module taints kernel. The module is loaded: # lsmod Module Size Used by rtc_rv8803 16384 0 Next I bind the driver to the i2c address 0x32: # echo i2c:rx8900 0x32 > /sys/class/i2c-adapter/i2c-1/new_device [ 176.871589] i2c i2c-1: new_device: Instantiated device i2c:rx8900 at 0x32 This does not give me a /dev/rtc device: # ls /dev/rtc* ls: cannot access '/dev/rtc*': No such file or directory The rtc is detected at address 0x32, but it's not claimed by any driver (that would have been indicated by UU instead of 32). # i2cdetect -y 1 0 1 2 3 4 5 6 7 8 9 a b c d e f 00: -- -- -- -- -- -- -- -- -- -- -- -- -- 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 20: -- -- -- -- -- -- -- -- -- 29 -- -- -- -- -- -- 30: -- -- 32 -- -- -- -- -- -- -- -- -- -- -- -- -- 40: -- -- -- -- -- -- -- -- -- 49 4a -- -- -- -- -- 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 60: -- -- -- -- -- -- -- -- 68 -- -- -- -- -- -- -- 70: -- -- -- -- -- -- -- -- What did I miss? Kind regards, Cedric [1] $ cat Makefile RV8803_DIR = $(shell pwd) KSRC = /lib/modules/$(KVER)/build KVER = $(shell uname -r) MODDESTDIR = /lib/modules/$(KVER)/kernel/drivers/rtc CROSS_COMPILE = AS = $(CROSS_COMPILE)as LD = $(CROSS_COMPILE)ld CC = $(CROSS_COMPILE)gcc CPP = $(CC) -E AR = $(CROSS_COMPILE)ar NM = $(CROSS_COMPILE)nm STRIP = $(CROSS_COMPILE)strip OBJCOPY = $(CROSS_COMPILE)objcopy OBJDUMP = $(CROSS_COMPILE)objdump DEPMOD = /sbin/depmod INSTALL = /usr/bin/install GREP = /bin/grep obj-m += rtc-rv8803.o all: modules modules: $(MAKE) -C $(KSRC) M=$(RV8803_DIR) CC=$(CC) modules install: modules @$(GREP) rtc-rv8803.ko /lib/modules/$(shell uname -r)/modules.dep && rm -fr $(MODDESTDIR)/rtc-rv8803.ko || echo "No system rtc-rv8803.ko file found. Install the new rtc-rv8803.ko driver into the system" $(INSTALL) -p -m 644 rtc-rv8803.ko $(MODDESTDIR) @$(DEPMOD) -a uninstall: @$(GREP) rtc-rv8803.ko /lib/modules/$(shell uname -r)/modules.dep && rm -fr $(MODDESTDIR)/rtc-rv8803.ko || echo "Remove the rtc-rv8803.ko driver from the system" @$(DEPMOD) -a clean: ________________________________________________________ Ihr Recht auf Privatsphäre. Schützen Sie Ihre Daten und wechseln jetzt zu eclipso Mail & Cloud - https://www.eclipso.de
