ARM-Linux驱动移植--RTC(实时时钟)移植
硬件平台：FL2440
内核版本：2.6.28
主机平台：Ubuntu 11.04
内核版本：2.6.39
原创作品，转载请标明出处http://blog.csdn.net/yming0221/article/details/6584285
首先修改内核源码/arch/arm/mach-s3c2410/mach-smdk2410.c
添加红色字体部分
static struct platform_device *smdk2410_devices[] __initdata = {
&s3c_device_usb,
&s3c_device_lcd,
&s3c_device_wdt,
&s3c_device_i2c,
&s3c_device_iis,
&s3c_device_sdi,
&s3c_device_dm9000,
&s3c_device_ts,
&s3c_device_rtc,
};
make zImage重新编译内核，然后烧写内核（编译内核前，make menuconfig时选择rtc相关的驱动，如下图）
烧写完成后启动开发板，启动信息如下：
+------------------------------------------------------------+
| FL2440 Bootloader VER-5.1 Modified By Yan Ming! |
|------------------------------------------------------------|
|------------------------------------------------------------|
|CPU ID is 0x32440001 |
|FCLK=400MHz,HCLK=100MHz,PCLK=50MHz, CPU is running at 400MHz|
|UPLL=96MHz, UCLK=48MHz |
|Serial port 0, Baud rate is 115200. |
|OS image stored in NAND Flash. |
|Autoboot delay is 2 seconds. |
+------------------------------------------------------------+
Set boot params = root=/dev/mtdblock3 init=/linuxrc load_ramdisk=0 console=ttyS
Load Kernel...
Uncompressing Linux.............................................................
Linux version 2.6.28.7 (yan@yan-laptop) (gcc version 3.4.1) #343 Sun Jul 3 19:11
CPU: ARM920T [41129200] revision 0 (ARMv4T), cr=c0007177
CPU: VIVT data cache, VIVT instruction cache
Machine: SMDK2410
ATAG_INITRD is deprecated; please update your bootloader.
Memory policy: ECC disabled, Data cache writeback
CPU S3C2440A (id 0x32440001)
MM: CPU does not support supersection mapping for 0x55000000000 at 0xf0d00000
S3C244X: core 400.000 MHz, memory 100.000 MHz, peripheral 50.000 MHz
S3C24XX Clocks, (c) 2004 Simtec Electronics
CLOCK: Slow mode (1.500 MHz), fast, MPLL on, UPLL on
Built 1 zonelists in Zone order, mobility grouping on. Total pages: 16256
Kernel command line: root=/dev/mtdblock3 init=/linuxrc load_ramdisk=0 console=t
irq: clearing pending ext status 00080000
irq: clearing subpending status 00000092
PID hash table entries: 256 (order: 8, 1024 bytes)
timer tcon=00500d00, tcnt a2c1, tcfg 0000020f,00000030, usec 00001eb8
Console: colour dummy device 80x30
console [ttySAC0] enabled
Dentry cache hash table entries: 8192 (order: 3, 32768 bytes)
Inode-cache hash table entries: 4096 (order: 2, 16384 bytes)
Memory: 64MB = 64MB total
Memory: 61120KB available (3288K code, 312K data, 144K init)
Calibrating delay loop... 199.47 BogoMIPS (lpj=498688)
Mount-cache hash table entries: 512
CPU: Testing write buffer coherency: ok
net_namespace: 288 bytes
NET: Registered protocol family 16
S3C2440: Initialising architecture
S3C2440: IRQ Support
S3C24XX DMA Driver, (c) 2003-2004,2006 Simtec Electronics
DMA channel 0 at c4808000, irq 33
DMA channel 1 at c4808040, irq 34
DMA channel 2 at c4808080, irq 35
DMA channel 3 at c48080c0, irq 36
S3C244X: Clock Support, DVS off
SCSI subsystem initialized
usbcore: registered new interface driver usbfs
usbcore: registered new interface driver hub
usbcore: registered new device driver usb
NET: Registered protocol family 2
IP route cache hash table entries: 1024 (order: 0, 4096 bytes)
TCP established hash table entries: 2048 (order: 2, 16384 bytes)
TCP bind hash table entries: 2048 (order: 1, 8192 bytes)
TCP: Hash tables configured (established 2048 bind 2048)
TCP reno registered
NET: Registered protocol family 1
NetWinder Floating Point Emulator V0.97 (extended precision)
Installing knfsd (copyright (C) 1996 [email protected]).
JFFS2 version 2.2. (NAND) (SUMMARY) 2001-2006 Red Hat, Inc.
yaffs Jul 3 2011 19:14:41 Installing.
msgmni has been set to 119
io scheduler noop registered
io scheduler anticipatory registered (default)
io scheduler deadline registered
io scheduler cfq registered
Console: switching to colour frame buffer device 40x30
fb0: s3c2410fb frame buffer device
lp: driver loaded but no devices found
ppdev: user-space parallel port driver
Serial: 8250/16550 driver4 ports, IRQ sharing enabled
s3c2440-uart.0: s3c2410_serial0 at MMIO 0x50000000 (irq = 70) is a S3C2440
s3c2440-uart.1: s3c2410_serial1 at MMIO 0x50004000 (irq = 73) is a S3C2440
s3c2440-uart.2: s3c2410_serial2 at MMIO 0x50008000 (irq = 76) is a S3C2440
brd: module loaded
loop: module loaded
dm9000 Ethernet Driver, V1.31
eth0: dm9000a at c487a300,c487e304 IRQ 51 MAC: 00:12:34:56:80:49 (chip)
Uniform Multi-Platform E-IDE driver
ide-gd driver 1.18
ide-cd driver 5.00
Driver 'sd' needs updating - please use bus_type methods
S3C24XX NAND Driver, (c) 2004 Simtec Electronics
s3c2440-nand s3c2440-nand: Tacls=3, 30ns Twrph0=7 70ns, Twrph1=3 30ns
NAND device: Manufacturer ID: 0xad, Chip ID: 0xda (Hynix NAND 256MiB 3,3V 8-bit)
NAND_ECC_NONE selected by board driver. This is not recommended !!
Scanning device for bad blocks
Bad eraseblock 1771 at 0x0dd60000
Creating 4 MTD partitions on "NAND 256MiB 3,3V 8-bit":
0x00000000-0x00100000 : "Boot"
0x00140000-0x00500000 : "MyApp"
0x00500000-0x00800000 : "Kernel"
0x00800000-0x0f800000 : "fs_yaffs"
usbmon: debugfs is not available
ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver
s3c2410-ohci s3c2410-ohci: S3C24XX OHCI
s3c2410-ohci s3c2410-ohci: new USB bus registered, assigned bus number 1
s3c2410-ohci s3c2410-ohci: irq 42, io mem 0x49000000
usb usb1: configuration #1 chosen from 1 choice
hub 1-0:1.0: USB hub found
hub 1-0:1.0: 2 ports detected
usbcore: registered new interface driver libusual
usbcore: registered new interface driver usbserial
USB Serial support registered for generic
usbcore: registered new interface driver usbserial_generic
usbserial: USB Serial Driver core
USB Serial support registered for FTDI USB Serial Device
usbcore: registered new interface driver ftdi_sio
ftdi_sio: v1.4.3:USB FTDI Serial Converters Driver
USB Serial support registered for pl2303
usbcore: registered new interface driver pl2303
pl2303: Prolific PL2303 USB to serial adaptor driver
mice: PS/2 mouse device common for all mice
S3C24XX RTC, (c) 2004,2006 Simtec Electronics
s3c2410-rtc s3c2410-rtc: rtc disabled, re-enabling
s3c2410-rtc s3c2410-rtc: rtc core: registered s3c as rtc0
s3c2440-sdi s3c2440-sdi: host detect has no irq available
mapped channel 0 to 0
s3c2440-sdi s3c2440-sdi: powered down.
s3c2440-sdi s3c2440-sdi: initialisation done.
s3c2440-sdi s3c2440-sdi: running at 0kHz (requested: 0kHz).
s3c2440-sdi s3c2440-sdi: running at 196kHz (requested: 195kHz).
s3c2440-sdi s3c2440-sdi: running at 196kHz (requested: 195kHz).
s3c2440-sdi s3c2440-sdi: running at 196kHz (requested: 195kHz).
s3c2440-sdi s3c2440-sdi: powered down.
usbcore: registered new interface driver usbhid
usbhid: v2.6:USB HID core driver
mapped channel 10 to 2
mapped channel 9 to 1
UDA1341 audio driver initialized
TCP cubic registered
NET: Registered protocol family 17
RPC: Registered udp transport module.
RPC: Registered tcp transport module.
s3c2410-rtc s3c2410-rtc: setting system clock to 2011-07-04 20:15:05 UTC (13098)
yaffs: dev is 32505859 name is "mtdblock3"
yaffs: passed flags ""
yaffs: Attempting MTD mount on 31.3, "mtdblock3"
yaffs: auto selecting yaffs2
yaffs: restored from checkpoint
yaffs_read_super: isCheckpointed 1
VFS: Mounted root (yaffs filesystem).
Freeing init memory: 144K
usb 1-1: new full speed USB device using s3c2410-ohci and address 2
usb 1-1: configuration #1 chosen from 1 choice
hub 1-1:1.0: USB hub found
hub 1-1:1.0: 4 ports detected
Mounting /proc,/sys,/dev......
Starting mdev......
init started: BusyBox v1.9.2 (2011-06-13 18:52:29 CST)
starting pid 900, tty ': '/etc/init.d/rcS'
dm9000 dm9000.0: WARNING: no IRQ resource flags set.
eth0: link down
Please press Enter to activate this console. eth0: link up, 100Mbps, full-duple1
后色部分显示RTC工作正常。
使用命令
date 命令修改系统时间后，执行hwclock -w，保存到硬件的实时时钟
每次开机执行hkclock -s,这样每次开机后，系统从硬件读取时间信息，保存到系统。