请教怎样将am335x外置的rtc1变为rtc0？

顶一下

因为am335x本来就有一个rtc，请问您这么修改的原因是什么?

因为希望断电保存时间，而电池电量有限，只能给rtc供电，所以使用了外置rtc。

你说的crash是什么现象

详细的打印明天上班后发出。大意是解析dtb过程中遇到了非法指针

启动过程中的打印如下，劳驾专家帮忙看看，内容有点长。

Starting kernel ...

[ 0.000000] Booting Linux on physical CPU 0x0
[ 0.000000] Linux version 3.14.26 (root@iis61-Lenovo) (gcc version 4.7.3 20130226 (prerelease) (crosstool-NG linaro-1.13.1-4.7-2013.03-20130313 - Linaro GCC 2013.03) ) #22 Tue Oct 18 19:42:11 CST 2016
[ 0.000000] CPU: ARMv7 Processor [413fc082] revision 2 (ARMv7), cr=10c5387d
[ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[ 0.000000] Machine model: TI AM335x EVM-SK
[ 0.000000] cma: CMA: reserved 16 MiB at 9e800000
[ 0.000000] Memory policy: Data cache writeback
[ 0.000000] CPU: All CPU(s) started in SVC mode.
[ 0.000000] AM335X ES2.1 (sgx neon )
[ 0.000000] Built 1 zonelists in Zone order, mobility grouping on. Total pages: 129792
[ 0.000000] Kernel command line: init=/linuxrc console=ttyO0,115200n8 root=/dev/ram0 rw ramdisk_size=98304 initrd=0x81000040,96M rootfstype=ext2 ip=192.168.1.231:192.168.1.61:192.168.1.1:255.255.255.0::eth0:off runmod=startB init=/linuxrc root=/dev/ram0 rw ramdisk_size=114688 initrd=0x81000040,112M
[ 0.000000] PID hash table entries: 2048 (order: 1, 8192 bytes)
[ 0.000000] Dentry cache hash table entries: 65536 (order: 6, 262144 bytes)
[ 0.000000] Inode-cache hash table entries: 32768 (order: 5, 131072 bytes)
[ 0.000000] Memory: 380272K/523264K available (4887K kernel code, 250K rwdata, 1640K rodata, 212K init, 213K bss, 142992K reserved, 0K highmem)
[ 0.000000] Virtual kernel memory layout:
[ 0.000000] vector : 0xffff0000 - 0xffff1000 ( 4 kB)
[ 0.000000] fixmap : 0xfff00000 - 0xfffe0000 ( 896 kB)
[ 0.000000] vmalloc : 0xe0800000 - 0xff000000 ( 488 MB)
[ 0.000000] lowmem : 0xc0000000 - 0xe0000000 ( 512 MB)
[ 0.000000] pkmap : 0xbfe00000 - 0xc0000000 ( 2 MB)
[ 0.000000] modules : 0xbf000000 - 0xbfe00000 ( 14 MB)
[ 0.000000] .text : 0xc0008000 - 0xc0667f9c (6528 kB)
[ 0.000000] .init : 0xc0668000 - 0xc069d0bc ( 213 kB)
[ 0.000000] .data : 0xc069e000 - 0xc06dc9a0 ( 251 kB)
[ 0.000000] .bss : 0xc06dc9a0 - 0xc0711e00 ( 214 kB)
[ 0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
[ 0.000000] NR_IRQS:16 nr_irqs:16 16
[ 0.000000] IRQ: Found an INTC at 0xfa200000 (revision 5.0) with 128 interrupts
[ 0.000000] Total of 128 interrupts on 1 active controller
[ 0.000000] OMAP clockevent source: timer2 at 24000000 Hz
[ 0.000014] sched_clock: 32 bits at 24MHz, resolution 41ns, wraps every 178956969942ns
[ 0.000035] OMAP clocksource: timer1 at 24000000 Hz
[ 0.000204] Console: colour dummy device 80x30
[ 0.000247] Calibrating delay loop... 718.02 BogoMIPS (lpj=3590144)
[ 0.119394] pid_max: default: 32768 minimum: 301
[ 0.119509] Security Framework initialized
[ 0.119580] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.119592] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.126874] CPU: Testing write buffer coherency: ok
[ 0.127271] Setting up static identity map for 0x804cb798 - 0x804cb7f0
[ 0.128254] devtmpfs: initialized
[ 0.130549] VFP support v0.3: implementor 41 architecture 3 part 30 variant c rev 3
[ 0.138299] omap_hwmod: tptc0 using broken dt data from edma
[ 0.138386] omap_hwmod: tptc1 using broken dt data from edma
[ 0.138464] omap_hwmod: tptc2 using broken dt data from edma
[ 0.170862] omap_hwmod: ecap0: cannot be enabled for reset (3)
[ 0.174029] omap_hwmod: eqep0: cannot be enabled for reset (3)
[ 0.177189] omap_hwmod: ehrpwm0: cannot be enabled for reset (3)
[ 0.180365] omap_hwmod: ecap1: cannot be enabled for reset (3)
[ 0.183524] omap_hwmod: eqep1: cannot be enabled for reset (3)
[ 0.186682] omap_hwmod: ehrpwm1: cannot be enabled for reset (3)
[ 0.189857] omap_hwmod: ecap2: cannot be enabled for reset (3)
[ 0.193019] omap_hwmod: eqep2: cannot be enabled for reset (3)
[ 0.196177] omap_hwmod: ehrpwm2: cannot be enabled for reset (3)
[ 0.226406] omap_hwmod: davinci_mdio: cannot be enabled for reset (3)
[ 0.226759] pinctrl core: initialized pinctrl subsystem
[ 0.227076] regulator-dummy: no parameters
[ 0.228551] NET: Registered protocol family 16
[ 0.230943] DMA: preallocated 256 KiB pool for atomic coherent allocations
[ 0.231491] cpuidle: using governor ladder
[ 0.231504] cpuidle: using governor menu
[ 0.237332] syscon 44e10000.control_module: regmap [mem 0x44e10000-0x44e107fb] registered
[ 0.238110] platform 49000000.edma: alias fck already exists
[ 0.238133] platform 49000000.edma: alias fck already exists
[ 0.238149] platform 49000000.edma: alias fck already exists
[ 0.238405] !!!!!!!!!!!omap_gpio_probe:gpio->start=44e07000
[ 0.238861] OMAP GPIO hardware version 0.1
[ 0.239150] !!!!!!!!!!!omap_gpio_probe:gpio->start=4804c000
[ 0.239865] !!!!!!!!!!!omap_gpio_probe:gpio->start=481ac000
[ 0.240535] !!!!!!!!!!!omap_gpio_probe:gpio->start=481ae000
[ 0.245055] omap-gpmc 50000000.gpmc: GPMC revision 6.0
[ 0.245076] gpmc_mem_init: disabling cs 0 mapped at 0x0-0x1000000
[ 0.247068] No ATAGs?
[ 0.253973] bio: create slab <bio-0> at 0
[ 0.261686] edma-dma-engine edma-dma-engine.0: TI EDMA DMA engine driver
[ 0.262314] !!!!!!!!!!!_enable_gpio_module:gpio-ctrl=0
[ 0.262347] vtt: 1500 mV
[ 0.264158] i2c-core: driver [palmas] using legacy suspend method
[ 0.264170] i2c-core: driver [palmas] using legacy resume method
[ 0.264513] SCSI subsystem initialized
[ 0.264787] usbcore: registered new interface driver usbfs
[ 0.264858] usbcore: registered new interface driver hub
[ 0.265176] usbcore: registered new device driver usb
[ 0.265562] omap_i2c 44e0b000.i2c: could not find pctldev for node /pinmux@44e10800/pinmux_i2c0_pins, deferring probe
[ 0.265590] platform 44e0b000.i2c: Driver omap_i2c requests probe deferral
[ 0.265717] pps_core: LinuxPPS API ver. 1 registered
[ 0.265726] pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giometti <giometti@linux.it>
[ 0.265753] PTP clock support registered
[ 0.266503] omap-mailbox 480c8000.mailbox: omap mailbox rev 0x400
[ 0.267609] Switched to clocksource timer1
[ 0.277914] NET: Registered protocol family 2
[ 0.278794] TCP established hash table entries: 4096 (order: 2, 16384 bytes)
[ 0.278853] TCP bind hash table entries: 4096 (order: 2, 16384 bytes)
[ 0.278904] TCP: Hash tables configured (established 4096 bind 4096)
[ 0.278984] TCP: reno registered
[ 0.278999] UDP hash table entries: 256 (order: 0, 4096 bytes)
[ 0.279019] UDP-Lite hash table entries: 256 (order: 0, 4096 bytes)
[ 0.279218] NET: Registered protocol family 1
[ 0.279585] RPC: Registered named UNIX socket transport module.
[ 0.279598] RPC: Registered udp transport module.
[ 0.279605] RPC: Registered tcp transport module.
[ 0.279612] RPC: Registered tcp NFSv4.1 backchannel transport module.
[ 0.279919] Trying to unpack rootfs image as initramfs...
[ 0.280803] rootfs image is not initramfs (no cpio magic); looks like an initrd
[ 1.046266] Freeing initrd memory: 114684K (c1001000 - c8000000)
[ 1.048308] futex hash table entries: 256 (order: -1, 3072 bytes)
[ 1.054500] VFS: Disk quotas dquot_6.5.2
[ 1.054714] Dquot-cache hash table entries: 1024 (order 0, 4096 bytes)
[ 1.057210] NFS: Registering the id_resolver key type
[ 1.057304] Key type id_resolver registered
[ 1.057313] Key type id_legacy registered
[ 1.057356] jffs2: version 2.2. (NAND) (SUMMARY) ?? 2001-2006 Red Hat, Inc.
[ 1.058221] msgmni has been set to 998
[ 1.059178] io scheduler noop registered
[ 1.059195] io scheduler deadline registered
[ 1.059238] io scheduler cfq registered (default)
[ 1.060272] pinctrl-single 44e10800.pinmux: 142 pins at pa f9e10800 size 568
[ 1.061628] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
[ 1.063568] omap_uart 44e09000.serial: no wakeirq for uart0
[ 1.063754] 44e09000.serial: ttyO0 at MMIO 0x44e09000 (irq = 88, base_baud = 3000000) is a OMAP UART0
[ 1.809569] console [ttyO0] enabled
[ 1.813697] omap_uart 48022000.serial: no wakeirq for uart0
[ 1.819650] 48022000.serial: ttyO1 at MMIO 0x48022000 (irq = 89, base_baud = 3000000) is a OMAP UART1
[ 1.829697] omap_uart 481a8000.serial: no wakeirq for uart0
[ 1.835604] 481a8000.serial: ttyO4 at MMIO 0x481a8000 (irq = 61, base_baud = 3000000) is a OMAP UART4
[ 1.845658] omap_uart 481aa000.serial: no wakeirq for uart0
[ 1.851597] 481aa000.serial: ttyO5 at MMIO 0x481aa000 (irq = 62, base_baud = 3000000) is a OMAP UART5
[ 1.862087] omap_rng 48310000.rng: OMAP Random Number Generator ver. 20
[ 1.875778] brd: module loaded
[ 1.882598] loop: module loaded
[ 1.886121] (hci_tty): inside hci_tty_init
[ 1.890652] (hci_tty): allocated 248, 0
[ 1.895585] mtdoops: mtd device (mtddev=name/number) must be supplied
[ 1.903099] nand: device found, Manufacturer ID: 0x2c, Chip ID: 0x38
[ 1.909759] nand: Micron MT29F8G08ABABAWP
[ 1.913940] nand: 1024MiB, SLC, page size: 4096, OOB size: 224
[ 1.920033] using OMAP_ECC_BCH16_CODE_HW ECC scheme
[ 1.925241] 13 ofpart partitions found on MTD device omap2-nand.0
[ 1.931609] Creating 13 MTD partitions on "omap2-nand.0":
[ 1.937245] 0x000000000000-0x000000080000 : "SPL"
[ 1.943329] 0x000000080000-0x000000100000 : "SP-L.backup1"
[ 1.950066] 0x000000100000-0x000000200000 : "U-Boot"
[ 1.956183] 0x000000200000-0x000000400000 : "U-Boo-t-Env"
[ 1.962901] 0x000000400000-0x000000a00000 : "kernel_a"
[ 1.969781] 0x000000a00000-0x000001e00000 : "ramdisk_a"
[ 1.978226] 0x000001e00000-0x000002400000 : "kernel_b"
[ 1.985083] 0x000002400000-0x000003800000 : "ramdisk_b"
[ 1.993539] 0x000003800000-0x000005b00000 : "config"
[ 2.003296] 0x000005b00000-0x000009b00000 : "custom"
[ 2.016027] 0x000009b00000-0x000029b00000 : "cache"
[ 2.074716] 0x000029b00000-0x000031b00000 : "log"
[ 2.093686] 0x000031b00000-0x000040000000 : "reserve"
[ 2.124063] registered master spi1
[ 2.128604] setup mode 0, 8 bits/w, 48000000 Hz max --> 0
[ 2.134627] registered child spi1.0
[ 2.138432] bonding: Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011)
[ 2.148526] usbcore: registered new interface driver asix
[ 2.154237] usbcore: registered new interface driver ax88179_178a
[ 2.160682] usbcore: registered new interface driver cdc_ether
[ 2.166842] usbcore: registered new interface driver smsc95xx
[ 2.172900] usbcore: registered new interface driver net1080
[ 2.178865] usbcore: registered new interface driver cdc_subset
[ 2.185080] usbcore: registered new interface driver zaurus
[ 2.191002] usbcore: registered new interface driver cdc_ncm
[ 2.197282] usbcore: registered new interface driver usb-storage
[ 2.203653] usbcore: registered new interface driver usbtest
[ 2.210958] 47401300.usb-phy supply vcc not found, using dummy regulator
[ 2.220028] musb-hdrc musb-hdrc.0.auto: Failed to request rx1.
[ 2.226146] musb-hdrc musb-hdrc.0.auto: musb_init_controller failed with status -517
[ 2.234300] platform musb-hdrc.0.auto: Driver musb-hdrc requests probe deferral
[ 2.249517] mousedev: PS/2 mouse device common for all mice
[ 2.256128] i2c-core: driver [rtc-ds1307] using legacy suspend method
[ 2.262908] i2c-core: driver [rtc-ds1307] using legacy resume method
[ 2.269710] i2c /dev entries driver
[ 2.273386] Driver for 1-wire Dallas network protocol.
[ 2.279904] omap_wdt: OMAP Watchdog Timer Rev 0x01: initial timeout 60 sec
[ 2.288188] omap_hsmmc 48060000.mmc: unable to get vmmc regulator -517
[ 2.295121] platform 48060000.mmc: Driver omap_hsmmc requests probe deferral
[ 2.302717] !!!!!!!!!!!_enable_gpio_module:gpio-ctrl=0
[ 2.308231] omap_hsmmc 481d8000.mmc: unable to get vmmc regulator -517
[ 2.315123] platform 481d8000.mmc: Driver omap_hsmmc requests probe deferral
[ 2.322861] usbcore: registered new interface driver usbhid
[ 2.328695] usbhid: USB HID core driver
[ 2.332848] platform 44d00000.wkup_m3: Driver wkup_m3 requests probe deferral
[ 2.340983] TCP: cubic registered
[ 2.344443] Initializing XFRM netlink socket
[ 2.349562] NET: Registered protocol family 10
[ 2.355384] sit: IPv6 over IPv4 tunneling driver
[ 2.361109] NET: Registered protocol family 17
[ 2.365776] NET: Registered protocol family 15
[ 2.370504] 8021q: 802.1Q VLAN Support v1.8
[ 2.374948] Key type dns_resolver registered
[ 2.380501] Unable to handle kernel NULL pointer dereference at virtual address 00000160
[ 2.389000] pgd = c0004000
[ 2.391820] [00000160] *pgd=00000000
[ 2.395555] Internal error: Oops - BUG: 5 [#1] ARM
[ 2.400546] Modules linked in:
[ 2.403738] CPU: 0 PID: 1 Comm: swapper Not tainted 3.14.26 #22
[ 2.409908] task: de074000 ti: de078000 task.ti: de078000
[ 2.415553] PC is at mutex_lock+0xc/0x30
[ 2.419656] LR is at rtc_read_scratch+0x24/0x7c
[ 2.424378] pc : [<c04ca808>] lr : [<c037af38>] psr: 60000113
[ 2.424378] sp : de079e50 ip : de079e60 fp : de079e5c
[ 2.436347] r10: de078000 r9 : 00000000 r8 : c06684d0
[ 2.441793] r7 : c06dd460 r6 : 00000001 r5 : 00000160 r4 : 00000000
[ 2.448595] r3 : 00000000 r2 : c06dd460 r1 : 00000001 r0 : 00000160
[ 2.455401] Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment kernel
[ 2.463020] Control: 10c5387d Table: 80004019 DAC: 00000015
[ 2.469008] Process swapper (pid: 1, stack limit = 0xde078238)
[ 2.475087] Stack: (0xde079e50 to 0xde07a000)

[ 2.479630] 9e40: de079e7c de079e60 c037af38 c04ca808
[ 2.488160] 9e60: 00000000 c06dd44c 00000001 000000bd de079ea4 de079e80 c06738cc c037af20
[ 2.496689] 9e80: de079ea4 00000007 c066f6f0 c069cfdc 00000007 c066b250 de079eb4 de079ea8
[ 2.505217] 9ea0: c066f7e4 c0673620 de079ec4 de079eb8 c066b274 c066f7d0 de079f4c de079ec8
[ 2.513747] 9ec0: c0008860 c066b25c 00000000 00000000 de079efc de079ee0 c00f5d8c 00000001
[ 2.522277] 9ee0: de079f04 de079ef0 c06684ec c022a2c8 dffff3f4 c04e9c74 de079f4c de079f08
[ 2.530806] 9f00: c0046130 c06684dc 00000000 00000007 dffff40a 00000007 c06655b0 c05da2b0
[ 2.539335] 9f20: de079f4c c069cfdc 00000007 c06dc9c0 000000bd c06684d0 c06925a8 c06925b0
[ 2.547864] 9f40: de079f94 de079f50 c0668ba4 c0008770 00000007 00000007 c06684d0 00000000
[ 2.556392] 9f60: 00000000 00000000 00000000 c06dc9c0 c04c4604 00000000 00000000 00000000
[ 2.564922] 9f80: 00000000 00000000 de079fac de079f98 c04c4618 c0668ac0 de078000 00000000
[ 2.573451] 9fa0: 00000000 de079fb0 c000e858 c04c4610 00000000 00000000 00000000 00000000
[ 2.581979] 9fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[ 2.590506] 9fe0: 00000000 00000000 00000000 00000000 00000013 00000000 00000000 00000000
[ 2.599027] Backtrace:
[ 2.601587] [<c04ca7fc>] (mutex_lock) from [<c037af38>] (rtc_read_scratch+0x24/0x7c)
[ 2.609670] [<c037af14>] (rtc_read_scratch) from [<c06738cc>] (am33xx_pm_init+0x2b8/0x3d4)
[ 2.618282] r7:000000bd r6:00000001 r5:c06dd44c r4:00000000
[ 2.624212] [<c0673614>] (am33xx_pm_init) from [<c066f7e4>] (am33xx_init_late+0x20/0x24)
[ 2.632644] r6:c066b250 r5:00000007 r4:c069cfdc
[ 2.637474] [<c066f7c4>] (am33xx_init_late) from [<c066b274>] (init_machine_late+0x24/0x30)
[ 2.646189] [<c066b250>] (init_machine_late) from [<c0008860>] (do_one_initcall+0xfc/0x118)
[ 2.654900] [<c0008764>] (do_one_initcall) from [<c0668ba4>] (kernel_init_freeable+0xf0/0x1b8)
[ 2.663874] r10:c06925b0 r9:c06925a8 r8:c06684d0 r7:000000bd r6:c06dc9c0 r5:00000007
[ 2.672058] r4:c069cfdc
[ 2.674712] [<c0668ab4>] (kernel_init_freeable) from [<c04c4618>] (kernel_init+0x14/0xf4)
[ 2.683235] r10:00000000 r9:00000000 r8:00000000 r7:00000000 r6:00000000 r5:c04c4604
[ 2.691416] r4:c06dc9c0
[ 2.694068] [<c04c4604>] (kernel_init) from [<c000e858>] (ret_from_fork+0x14/0x3c)
[ 2.701958] r4:00000000 r3:de078000
[ 2.705694] Code: e89da9f0 e1a0c00d e92dd800 e24cb004 (e1902f9f)
[ 2.712106] ---[ end trace 5df52fb0b7152fc4 ]---
[ 2.716948] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
[ 2.716948]

不注释rtc0，此时会正常启动，附近打印如下：

...

[ 2.232502] 8021q: 802.1Q VLAN Support v1.8
[ 2.236966] Key type dns_resolver registered
[ 2.242530] PM: bootloader does not support rtc-only!
[ 2.247810] ThumbEE CPU extension supported.
[ 2.252336] Registering SWP/SWPB emulation handler
[ 2.258642] regulator-dummy: disabling
[ 2.265147] DCDC1: at 1500 mV
[ 2.269286] vdd_mpu: 925 <--> 1375 mV at 1275 mV
[ 2.275065] vdd_core: 925 <--> 1150 mV at 1125 mV
[ 2.280955] LDO1: at 1800 mV
[ 2.284910] LDO2: 1800 <--> 3300 mV at 3300 mV
[ 2.290508] LDO3: 1800 <--> 3300 mV at 3300 mV
[ 2.295769] LDO4: at 3300 mV
[ 2.299526] tps65217 0-0024: TPS65217 ID 0xe version 1.2
[ 2.305568] magic=8203, bytlen=2048
[ 2.310021] at24 0-0050: 2048 byte 24c16 EEPROM, writable, 16 bytes/write
[ 2.317669] ds1307_probe:Tmp=0x83
[ 2.321381] ds1307_probe:Read again tmp=0x83
[ 2.326702] rtc-ds1307 0-0068: rtc core: registered ds1338 as rtc1
[ 2.333190] rtc-ds1307 0-0068: 56 bytes nvram
[ 2.337757] omap_i2c 44e0b000.i2c: bus 0 rev0.11 at 400 kHz
[ 2.347287] musb-hdrc musb-hdrc.0.auto: MUSB HDRC host driver

....

你的外置RTC是I2C接口的RTC芯片吧？应该加到I2C总线设备中。

另外不要把原有的RTC注掉，直接disable就可以了。

请问您的问题是怎么解决的呢？能简单写一下处理思路吗，我这边用的和您一样的内核，现象也一样。

这个问题当时没能解决，试过disable rtc0，但不好使。

最近升级了文件系统，使用ti 2.0或者2.1里面的文件系统（使用的是支持sysvinit的最后一个版本，后续版本支持systemd，比较麻烦），替换了之前的文件系统（使用busybox init），这个问题神奇般地解决了。启动脚本自动将rtc指向了rtc1，如下所示：

# ll /dev/rtc*
lrwxrwxrwx 1 iis root 4 Apr 6 2016 /dev/rtc -> rtc1
crw------- 1 iis root 254, 0 Apr 6 2016 /dev/rtc0
crw------- 1 iis root 254, 1 Apr 6 2016 /dev/rtc1

首先感谢您的回复。我这边在内核里尝试配置了这个时钟源，但是没有什么效果，我再看看有没有其他的办法配置。

内核的设置跟我一样。

实际上，这个问题也可以这样解决：

在通过inittab初始化系统时，用脚本将/dev/rtc指向/dev/rtc1，然后执行/etc/init.d/hwclock.sh start，就能实现用rtc时钟修改系统时钟的效果。

如果使用sysvinit，以及默认的启动脚本，这些操作应该是自动完成的。