最近在调试一块使用了AM3359的工控板，这里的硬件设计上是没有电源管理芯片的，想问一下论坛的工作人员以及各位工程师，我这里要使用rtc功能，应该做一些什么配置呢？开机能执行hwclock -w命令，但是一掉电之后，系统的时间就不对了。
[ 1.090646] omap_rtc 44e3e000.rtc: rtc core: registered 44e3e000.rtc as rtc0
[ 1.098334] i2c /dev entries driver
[ 1.102992] pinctrl-single 44e10800.pinmux: pin 44e10960.0 already requested by 481a6000.serial; cannot claim for 48060000.mmc
[ 1.114451] pinctrl-single 44e10800.pinmux: pin-88 (48060000.mmc) status -22
[ 1.121535] pinctrl-single 44e10800.pinmux: could not request pin 88 (44e10960.0) from group mmc0_pins_default on device pinctrl-single
[ 1.133852] omap_hsmmc 48060000.mmc: Error applying setting, reverse things back
[ 1.178863] NET: Registered protocol family 10
[ 1.179442] omap_hsmmc 48060000.mmc: exceeding card's volts
[ 1.193545] sit: IPv6 over IPv4 tunneling driver
[ 1.199011] NET: Registered protocol family 17
[ 1.203636] Key type dns_resolver registered
[ 1.208126] omap_voltage_late_init: Voltage driver support not added
[ 1.217550] omap-gpmc 50000000.gpmc: GPMC revision 6.0
[ 1.220476] mmc0: host does not support reading read-only switch, assuming write-enable
[ 1.222452] mmc0: new high speed SDHC card at address 0007
[ 1.232563] mmcblk0: mmc0:0007 SD16G 14.5 GiB
[ 1.235018] mmcblk0: p1 p2
[ 1.246070] gpmc_mem_init: disabling cs 0 mapped at 0x0-0x1000000
[ 1.253808] nand: device found, Manufacturer ID: 0x01, Chip ID: 0xdc
[ 1.260194] nand: AMD/Spansion S34ML04G2
[ 1.264138] nand: 512 MiB, SLC, erase size: 128 KiB, page size: 2048, OOB size: 128
[ 1.271859] nand: using OMAP_ECC_BCH8_CODE_HW ECC scheme
[ 1.277285] 10 ofpart partitions found on MTD device 8000000.nand
[ 1.283408] Creating 10 MTD partitions on "8000000.nand":
[ 1.288841] 0x000000000000-0x000000020000 : "NAND.SPL"
[ 1.295476] 0x000000020000-0x000000040000 : "NAND.SPL.backup1"
[ 1.302718] 0x000000040000-0x000000060000 : "NAND.SPL.backup2"
[ 1.309850] 0x000000060000-0x000000080000 : "NAND.SPL.backup3"
[ 1.316971] 0x000000080000-0x0000000c0000 : "NAND.u-boot-spl-os"
[ 1.324359] 0x0000000c0000-0x0000001c0000 : "NAND.u-boot"
[ 1.331461] 0x0000001c0000-0x0000001e0000 : "NAND.u-boot-env"
[ 1.338600] 0x0000001e0000-0x000000200000 : "NAND.u-boot-env.backup1"
[ 1.346336] 0x000000200000-0x000000a00000 : "NAND.kernel"
[ 1.356607] 0x000000a00000-0x000020000000 : "NAND.file-system"
[ 1.590120] omap_rtc 44e3e000.rtc: setting system clock to 2000-01-01 00:00:00 UTC (946684800)
[ 1.624514] EXT4-fs (mmcblk0p2): mounted filesystem with ordered data mode. Opts: (null)
[ 1.632729] VFS: Mounted root (ext4 filesystem) on device 179:2.
ps：我看了一下原理图，RTC相关的引脚配置模式是Rtc-Only，其中标号VDD1V8_RTC是纽扣电池经过处理之后得到的电压：
