Anyone know the rtc M41T56?

i try follow the (this is for ds1307)

the i2cdetect -y -r 1 find the right value “68”
and can use the i2cdump -y 1 0x68 to see the memory

with the command “hwclock -r -f /dev/rtc1” received the error “hwclock: ioctl(RTC_RD_TIME) to /dev/rtc1 to read the time failed: Invalid argument”

tryed to change ds1307 to m41t56 in the command “echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device”

but then dont mount the rtc1

i am new with beaglebone and rtc
i am using the debian version from “
i think that need the driver but i dont find in apt using m41t56 as keyword

anyone know how use this rtc? or can point docs for this rtc?

ps. sorry for the bad english