关于nand flash驱动 无法工作的问题

昨天按照 linux一直开发实战指南 在弄nand flash。可是怎么弄都不成功，具体如下：

load Image of Linux...Uncompressing Linux................................................................................................................................... done, booting the kernel.
Linux version 2.6.32.2 (ldomain) (gcc version 4.3.2 (Sourcery G++ Lite 2008q3-72) ) #4 Thu Jun 3 17:01:52 CST 2010
CPU: ARM920T [41129200] revision 0 (ARMv4T), cr=c0007177
CPU: VIVT data cache, VIVT instruction cache
Machine: My mini2440 Development board
ATAG_INITRD is deprecated; please update your bootloader.
Memory policy: ECC disabled, Data cache writeback
CPU S3C2440A (id 0x32440001)
S3C24XX Clocks, (c) 2004 Simtec Electronics
S3C244X: core 405.000 MHz, memory 101.250 MHz, peripheral 50.625 MHz
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: noinitrd root=/dev/mtdblock3 init=/linuxrc console=ttySAC0
PID hash table entries: 256 (order: -2, 1024 bytes)
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: 60500KB available (3672K code, 417K data, 132K init, 0K highmem)
SLUB: Genslabs=11, HWalign=32, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
Hierarchical RCU implementation.
NR_IRQS:85
irq: clearing subpending status 00000002
Console: colour dummy device 80x30
console [ttySAC0] enabled
Calibrating delay loop... 201.93 BogoMIPS (lpj=504832)
Mount-cache hash table entries: 512
CPU: Testing write buffer coherency: ok
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
bio: create slab at 0
usbcore: registered new interface driver usbfs
usbcore: registered new interface driver hub
usbcore: registered new device driver usb
s3c-i2c s3c2440-i2c: slave address 0x10
s3c-i2c s3c2440-i2c: bus frequency set to 98 KHz
s3c-i2c s3c2440-i2c: i2c-0: S3C I2C adapter
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
RPC: Registered udp transport module.
RPC: Registered tcp transport module.
RPC: Registered tcp NFSv4.1 backchannel transport module.
JFFS2 version 2.2. (NAND) 漏 2001-2006 Red Hat, Inc.
ROMFS MTD (C) 2007 Red Hat, Inc.
msgmni has been set to 118
alg: No test for stdrng (krng)
io scheduler noop registered
io scheduler anticipatory registered (default)
io scheduler deadline registered
io scheduler cfq registered
Console: switching to colour frame buffer device 60x53
fb0: s3c2410fb frame buffer device
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
S3C24XX NAND Driver, (c) 2004 Simtec Electronics
s3c24xx-nand s3c2440-nand: Tacls=4, 39ns Twrph0=8 79ns, Twrph1=8 79ns
Unable to handle kernel NULL pointer dereference at virtual address 00000018
pgd = c0004000
[00000018] *pgd=00000000
Internal error: Oops: 5 [#1]
last sysfs file:
Modules linked in:
CPU: 0    Not tainted  (2.6.32.2 #4)
PC is at s3c24xx_nand_probe+0x2d8/0x514
LR is at s3c24xx_nand_probe+0x1a4/0x514
pc : []    lr : []    psr: 60000013
sp : c3823f08  ip : 00000000  fp : 00000001
r10: 00000000  r9 : 00000000  r8 : 00000000
r7 : c03e5388  r6 : 00000000  r5 : c39b0640  r4 : c3863800
r3 : 00000001  r2 : c3863988  r1 : c4c00000  r0 : 00000002
Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment kernel
Control: c000717f  Table: 30004000  DAC: 00000017
Process swapper (pid: 1, stack limit = 0xc3822270)
Stack: (0xc3823f08 to 0xc3824000)
3f00:                   00000000 c00d398c c385a2d0 00000000 00000000 c03e5390
3f20: c03e5390 c03fbb40 c39ad960 c03fa5f8 00000000 00000000 00000000 c01c51d8
3f40: c03e5390 c01c43c4 c03e5390 c03e53c4 c03fbb40 c39ad960 c03fa5f8 c01c44d4
3f60: 00000000 c01c4478 c03fbb40 c01c3ca4 c3804938 c38474b0 c00220dc c03fbb40
3f80: c03fbb40 c01c3604 c039066f c039066f 00000006 c00220dc 00000000 c03fbb40
3fa0: c001a8b4 00000000 00000000 c01c47a0 c00220dc 00000000 00000000 c001a8b4
3fc0: 00000000 c002937c c001a8b4 c03ffa34 c0407540 c0022244 c00220dc 00000000
3fe0: 00000000 00000000 00000000 c00083f8 00000000 c002a854 33cc33cc 33cc33cc
[] (s3c24xx_nand_probe+0x2d8/0x514) from [] (platform_drv_probe+0x18/0x1c)
[] (platform_drv_probe+0x18/0x1c) from [] (driver_probe_device+0xa8/0x15c)
[] (driver_probe_device+0xa8/0x15c) from [] (__driver_attach+0x5c/0x7c)
[] (__driver_attach+0x5c/0x7c) from [] (bus_for_each_dev+0x48/0x78)
[] (bus_for_each_dev+0x48/0x78) from [] (bus_add_driver+0x98/0x21c)
[] (bus_add_driver+0x98/0x21c) from [] (driver_register+0xa4/0x130)
[] (driver_register+0xa4/0x130) from [] (do_one_initcall+0x5c/0x1b4)
[] (do_one_initcall+0x5c/0x1b4) from [] (kernel_init+0x94/0x10c)
[] (kernel_init+0x94/0x10c) from [] (kernel_thread_exit+0x0/0x8)
Code: e584321c e58420c4 e58452ac e58482a8 (e5983018)
---[ end trace fef4b2b65d07ac6c ]---
Kernel panic - not syncing: Attempted to kill init!
[] (unwind_backtrace+0x0/0xdc) from [] (panic+0x40/0x120)
[] (panic+0x40/0x120) from [] (do_exit+0x64/0x58c)
[] (do_exit+0x64/0x58c) from [] (die+0x15c/0x180)
[] (die+0x15c/0x180) from [] (__do_kernel_fault+0x64/0x74)
[] (__do_kernel_fault+0x64/0x74) from [] (do_page_fault+0x1b8/0x1cc)
[] (do_page_fault+0x1b8/0x1cc) from [] (do_DataAbort+0x34/0x94)
[] (do_DataAbort+0x34/0x94) from [] (__dabt_svc+0x40/0x60)
Exception stack(0xc3823ec0 to 0xc3823f08)
3ec0: 00000002 c4c00000 c3863988 00000001 c3863800 c39b0640 00000000 c03e5388
3ee0: 00000000 00000000 00000000 00000001 00000000 c3823f08 c01e9eb0 c01e9fe4
3f00: 60000013 ffffffff
[] (__dabt_svc+0x40/0x60) from [] (s3c24xx_nand_probe+0x2d8/0x514)
[] (s3c24xx_nand_probe+0x2d8/0x514) from [] (platform_drv_probe+0x18/0x1c)
[] (platform_drv_probe+0x18/0x1c) from [] (driver_probe_device+0xa8/0x15c)
[] (driver_probe_device+0xa8/0x15c) from [] (__driver_attach+0x5c/0x7c)
[] (__driver_attach+0x5c/0x7c) from [] (bus_for_each_dev+0x48/0x78)
[] (bus_for_each_dev+0x48/0x78) from [] (bus_add_driver+0x98/0x21c)
[] (bus_add_driver+0x98/0x21c) from [] (driver_register+0xa4/0x130)
[] (driver_register+0xa4/0x130) from [] (do_one_initcall+0x5c/0x1b4)
[] (do_one_initcall+0x5c/0x1b4) from [] (kernel_init+0x94/0x10c)
[] (kernel_init+0x94/0x10c) from [] (kernel_thread_exit+0x0/0x8)

后来网上又是猛查，说是上面红色的地方的问题。
因为 mini2440的 flash的参数应该是：

S3C24XX NAND Driver, (c) 2004 Simtec Electronics
s3c2440-nand s3c2440-nand: Tacls=3, 29ns Twrph0=7 69ns, Twrph1=3 29ns

从以上差别可以看出我们 按照友善提供的Linux移植开发实战所修改的下面一个结构体里设置的参数并没有生效：
static struct s3c2410_platform_nand mini2440_nand_info = {
        .tacls          = 20,
        .twrph0         = 60,
        .twrph1         = 20,
        .nr_sets        = ARRAY_SIZE(mini2440_nand_sets),
        .sets           = mini2440_nand_sets,
};
以上的结构体是mini2440开发板上使用的nand flash的一些配置信息，其中包括芯片操作时序信息。
查看nand flash相应的datasheet里面对nand flash控制器的NFCONF寄存器有如下描述
CLE/ALE是高电平使能 而TACLS是CLE/ALE使能的持续时间，也就是CLE/ALE信号线高电平持续的时间；
nWE是低电平使能 TWRPH0对应于nWE的使能持续时间，也就是nWE信号线低电平的持续时间；
而TWRPH1对应于nWE信号线高电平的持续时间。

具体如下图：

而 通过内核打印信息+Source Insight查找到输出
S3C24XX NAND Driver, (c) 2004 Simtec Electronics
s3c24xx-nand s3c2440-nand: Tacls=4, 39ns Twrph0=8 79ns, Twrph1=8 79ns
语句信息的函数在内核源码中nand flash驱动程序里的drivers/mtd/nand/s3c2410.c文件中。

分析Linux内核中的nand flash驱动drivers/mtd/nand/s3c2410.c文件中的相应函数，
其中的static int s3c2410_nand_setrate(struct s3c2410_nand_info *info)函数发现：
    struct s3c2410_platform_nand *plat = info->platform;
        int tacls_max = (info->cpu_type == TYPE_S3C2412) ? 8 : 4;   
         …………
    info->clk_rate = clkrate;
        clkrate /= 1000;        /* turn clock into kHz for ease of use */

        if (plat != NULL) {
                tacls = s3c_nand_calc_rate(plat->tacls, clkrate, tacls_max);
                twrph0 = s3c_nand_calc_rate(plat->twrph0, clkrate, 8);
                twrph1 = s3c_nand_calc_rate(plat->twrph1, clkrate, 8);
        } else {      
          /* default timings */
                tacls = tacls_max;
                twrph0 = 8;
                twrph1 = 8;      
            }

        if (tacls < 0 || twrph0 < 0 || twrph1 < 0) {
                dev_err(info->device, "cannot get suitable timings\n");
                return -EINVAL;
        }

        dev_info(info->device, "Tacls=%d, %dns Twrph0=%d %dns, Twrph1=%d %dns\n",
               tacls, to_ns(tacls, clkrate), twrph0, to_ns(twrph0, clkrate), twrph1, to_ns(twrph1, clkrate));

由以上内容可以看出，内核并没有使用我们的mini2440_nand_info结 构体中的配置，而是使用了它的默认配给，即
} else {      
          /* default timings */
                tacls = tacls_max;
                twrph0 = 8;
                twrph1 = 8;      
            }
中的配置信 息。这点和我们改的内核输出s3c24xx-nand s3c2440-nand: Tacls=4, 39ns Twrph0=8 79ns, Twrph1=8 79ns完全符合。

因此可以判断我们需要在mach-mini2440.c的mini2440_machine_init（）函数中增加s3c_device_nand.dev.platform_data = &mini240_nand_info;
（注： 原来论坛上  讲的方法 增加 s3c_nand_set_platdata(&mini2440_nand_info);是不行的，因为 这个函数在 2.6.32中没有，我在2.6.34中找到了。）
语 句来设置当前平台所使用的存储nand flash配置的相应结构体mini2440_nand_info。

解决方法：
只需在 mach-mini2440.c的初始化函数mini2440_machine_init(void)里加入s3c_device_nand.dev.platform_data = &mini240_nand_info;即 可。

严重参考：