天嵌IMX6开发板测试-第一篇

1.看下开发板介绍

 品牌: 天嵌
 CPU型号: NXP i.MX6Q
 架构: Cortex_A9
 主频: *1GHz
 内存: 2GB DDR3
 存储: 8GB eMMC FLA（64GB可扩）

2. 看下相关驱动啥的。

驱动	在内核中的源码位置	系统中的设备名称
emmc/sdcard 驱动	drivers/mmc/host：sdhci-esdhc-imx.c sdhci.c sdhci-platform.c sdhci-pltfm.c	/dev/mmcblk*
LCD 与 LVDS 驱动	drivers/video/mxc/ldb.c mxc_dispdrv.c mxc_dvi.c mxc_ipuv3_fb.c mxc_lcdif.c	/dev/fb*
电阻触摸屏驱动	drivers/input/touchscreen/tsc2007.module	dev/input/event*
电容触摸屏驱动	drivers/input/touchscreen/gt811.module	dev/input/event*
USB otg 驱动	drivers/usb/otg/fsl_otg.c
有线网络驱动	drivers/net/fec.module	eth0
串口驱动	drivers/tty/serial/imx.c mxc_uart_early.c serial_core.c	/dev/ttySAC*
sgtl5000声卡驱动	sound/soc/imx/*	/dev/snd/*
I2C 驱动	drivers/i2c/busses/i2c-imx.c
按键驱动	drivers/input/keyboard/gpio_keys.c	dev/input/event*
红外驱动	drivers/input/keyboard/tq_hs0038.module	dev/input/event*
背光灯驱动	drivers/video/backlight/pwm_bl.c drivers/video/backlight/backlight.c
pwm 驱动	arch/arm/plat-mxc/pwm.c
RTC 驱动	drivers/rtc/rtc-pcf8563.c	/dev/rtc0
看门狗驱动	drivers/watchdog/imx2_wdt.c	/dev/watchdog
多媒体摄像头驱动	drivers/media/video/mxc/capture/*	/dev/video*

3. 看下资料的下载，在淘宝找的

下载资料	下载链接
TQIMX6_android_V3.12.part01	http://pan.baidu.com/s/1slA1doD 密码：vpad
TQIMX6_android_V3.12.part02	http://pan.baidu.com/s/1mikSS1E 密码：cac7
TQIMX6_android_V3.12.part03	http://pan.baidu.com/s/1kVmqJKb 密码：x5yj
TQIMX6_android_V3.12.part04	http://pan.baidu.com/s/1eR9RvRO 密码：vwra
TQIMX6_android_V3.12.part05	http://pan.baidu.com/s/1hrIAHOK 密码：nhfe
TQIMX6_android_V3.12.part06	http://pan.baidu.com/s/1gfLAL4R 密码：qyu6
TQIMX6_android_V3.12.part07	http://pan.baidu.com/s/1hsgXpwK 密码：l7h7
TQIMX6_android_V3.12.part08	http://pan.baidu.com/s/1dFniWmP 密码：bo8r
TQIMX6_android_V3.12.part09	http://pan.baidu.com/s/1bo7p7f5 密码：nva2
TQIMX6_android_V3.12.part10	http://pan.baidu.com/s/1mhRqdQw 密码：hawo
Android镜像（6.0）	http://pan.baidu.com/s/1qXEWAxm 密码：pljv
Linux镜像（4.1）	http://pan.baidu.com/s/1dFpQUNv 密码：2b8l
Linux文件系统镜像.part1	http://pan.baidu.com/s/1jHPYnBK 密码：3t0h
Linux文件系统镜像.part2	http://pan.baidu.com/s/1bo9XzD9 密码：pgim
Linux平台工具	http://pan.baidu.com/s/1miGGWPU 密码：5fhr
Linux资源	http://pan.baidu.com/s/1skS1Oc9 密码：g1ud
Windows平台工具	http://pan.baidu.com/s/1pLMG23x 密码：hihw
配套电路图	http://pan.baidu.com/s/1hsw6ulm 密码：92ym
配套教材集	https://pan.baidu.com/s/1nvQj4N3 密码：g9v7
配套芯片手册	http://pan.baidu.com/s/1dEUSeL7 密码：sx1b
TQIMX6Q(V3) QT5.5开发境搭建	http://pan.baidu.com/s/1i4Q3hTb 密码：vh9f
Qt快速入门攻略	http://www.armbbs.net/forum.php?mod=viewthread&tid=21338&extra=

4. 看下uboot的源码，根据手册是

 ./build_sh 编译

5. 是的，你比较厉害，-j8用8个线程去编译。

 export ARCH=arm
 export CROSS_COMPILE=arm-linux-
 make mx6q_sabresd_android_config
 make -j8

6. 找到mx6q_sabresd_android_config，没搞明白，2个make可以放在一起？打开IMX6_CoreC_CD\Linux 源码包\uboot源码\uboot_IMX6_CoreC_1.3.4_for_Linux\Makefile

 mx6q_sabresd_config            \
 mx6q_sabresd_android_config             \
 mx6q_sabresd_mfg_config            \
 mx6q_sabresd_iram_config    : unconfig
     @[ -z "$(findstring iram_,$@)" ] || \
         { echo "TEXT_BASE = 0x00907000" >$(obj)board/freescale/mx6q_sabresd/config.tmp ; \
           echo "... with iram configuration" ; \
         }
     @$(MKCONFIG) $(@:_config=) arm arm_cortexa8 mx6q_sabresd freescale mx6

7. 上面的几个参数，arm是构架 arm_cortexa8是CPU型号 mx6q_sabresd是板子的型号 freescale mx6

8. 找到链接文件uboot_IMX6_CoreC_1.3.4_for_Linux\board\freescale\mx6q_sabresd\u-boot.lds

 OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
 OUTPUT_ARCH(arm)
 ENTRY(_start)
 SECTIONS
 {
     . = 0x00000000;  //放置的起始位置

     . = ALIGN(); //4字节对齐
     .text       :   //代码段
     {
       /* WARNING - the following is hand-optimized to fit within    */
       /* the sector layout of our flash chips!    XXX FIXME XXX    */
       board/freescale/mx6q_sabresd/flash_header.module    (.text.flasheader)  //天嵌定制？
       cpu/arm_cortexa8/start.o //启动文件
       board/freescale/mx6q_sabresd/libmx6q_sabresd.a    (.text)
       lib_arm/libarm.a        (.text)
       net/libnet.a            (.text)
       drivers/mtd/libmtd.a        (.text)
       drivers/mmc/libmmc.a        (.text)

       . = DEFINED(env_offset) ? env_offset : .;
       common/env_embedded.o(.text)

       *(.text)
     }

     . = ALIGN();  //只读数据段,ROM
     .rodata : { *(SORT_BY_ALIGNMENT(SORT_BY_NAME(.rodata*))) }

     . = ALIGN(); //数据段
     .data : { *(.data) }

     . = ALIGN();
     .got : { *(.got) }

     . = .;
     __u_boot_cmd_start = .;
     .u_boot_cmd : { *(.u_boot_cmd) }
     __u_boot_cmd_end = .;

     . = ALIGN();
     _end_of_copy = .; /* end_of ROM copy code here */

     /* Extend to align to 0x1000, then put the Hab Data */
     . = ALIGN(0x1000);
     __hab_data = .;
     . = . + 0x2000;
     __data_enc_key = .;
     /* actually, only 64bytes are needed, but this generates
         a size multiple of 512bytes, which is optimal for SD boot */
     . = . + 0x200;
     __hab_data_end = .;
     /* End of Hab Data, Place it before BSS section */

     __bss_start = .;
     .bss : { *(.bss) }
     _end = .;
 }

9. 第一行，这个不清楚是啥，天嵌定制的？

board/freescale/mx6q_sabresd/flash_header.module    (.text.flasheader)

10.第2个链接的文件是start.c

#include <config.h>
#include <version.h>

.globl _start  //定义一个全局可见的变量
_start: b    reset  //问题，哪里算是_start的结束？下一个冒号的位置
    ldr    pc, _undefined_instruction  //未定义指令
    ldr    pc, _software_interrupt //软件中断向量
    ldr    pc, _prefetch_abort //预取指令中断向量
    ldr    pc, _data_abort//数据操作异常向量
    ldr    pc, _not_used /、未使用
    ldr    pc, _irq//慢速中断向量
    ldr    pc, _fiq//快速中断向量

_undefined_instruction: .word undefined_instruction
_software_interrupt:    .word software_interrupt
_prefetch_abort:    .word prefetch_abort
_data_abort:        .word data_abort
_not_used:        .word not_used
_irq:            .word irq
_fiq:            .word fiq
_pad:            .word 0x12345678 /* now 16*4=64 */
.global _end_vect
_end_vect:

11. 上面的.wordirq说是是什么意思，点是什么意思？加点的是伪指令，不会被编译的，理解如下.word是一个汇编伪指令，表示是一个字节，.word是伪操作，用于分配一小段字内存单元

 _software_interrupt:    .word software_interrupt  //_software_interrupt = software_interrupt

12. 下面是reset的代码

 reset:
     /*
      * set the cpu to SVC32 mode
      *//ARM有7种模式，SVC是特权模式，可以访问所有寄存器
     mrs    r0, cpsr
     bic    r0, r0, #0x1f
     orr    r0, r0, #0xd3
     msr    cpsr,r0
     /* the mask ROM code should have PLL and others stable */
 #ifndef CONFIG_SKIP_LOWLEVEL_INIT
     bl    cpu_init_crit
 #endif

13.首先会将CPU的工作模式设置为svc32模式，然后便调用 cpu_init_crit ，需要注意的是，这里使用的是 bl 指令，也就是说在运行完 cpu_init_crit 标号处的代码之后，会通过这个指令返回来

 mov    pc, lr            @ back to my caller

14. 跳转到cpu_init_crit

 cpu_init_crit:
     /*
      * Invalidate L1 I/D
      */
     mov    r0, #            @ set up for MCR
     mcr    p15, , r0, c8, c7,     @ invalidate TLBs
     mcr    p15, , r0, c7, c5,     @ invalidate icache

     /*
      * disable MMU stuff and caches
      */
     mrc    p15, , r0, c1, c0,
     bic    r0, r0, #0x00002000    @ clear bits  (--V-)
     bic    r0, r0, #0x00000007    @ clear bits : (-CAM)
     orr    r0, r0, #0x00000002    @ set bit  (--A-) Align
     orr    r0, r0, #0x00000800    @ set bit  (Z---) BTB
     mcr    p15, , r0, c1, c0, 

     /*
      * Jump to board specific initialization...
      * The Mask ROM will have already initialized
      * basic memory. Go here to bump up clock rate and handle
      * wake up conditions.
      */
     mov    ip, lr            @ persevere link reg across call
     bl    lowlevel_init        @ go setup pll,mux,memory
     mov    lr, ip            @ restore link
     mov    pc, lr            @ back to my caller

15.找到lowlevel_init这个函数，E:\arm_a\IMX6_CoreC_CD\Linux 源码包\uboot源码\uboot_IMX6_CoreC_1.3.4_for_Linux\board\freescale\mx6q_sabresd\lowlevel_init.S

 .globl lowlevel_init
 lowlevel_init:
     inv_dcache
     init_l2cc
     init_aips
     init_clock
     mov pc, lr

16. 接下来一个尴尬的问题，不知道程序接下来往哪里走了！！假设汇编代码是顺序执行的，那么接下来是relocate

 relocate:                @ relocate U-Boot to RAM
     adr    r0, _start        @ r0 <- current position of code
     ldr    r1, _TEXT_BASE        @ test if we run from flash or RAM
     cmp    r0, r1            @ don't reloc during debug
     beq    stack_setup

     ldr    r2, _armboot_start
     ldr    r3, _bss_start
     sub    r2, r3, r2        @ r2 <- size of armboot
     add    r2, r0, r2        @ r2 <- source end address

 copy_loop:                @ copy  bytes at a time
     ldmia    r0!, {r3 - r10}        @ copy from source address [r0]
     stmia    r1!, {r3 - r10}        @ copy to   target address [r1]
     cmp    r0, r2            @ until source end addreee [r2]
     ble    copy_loop
 #endif    /* CONFIG_SKIP_RELOCATE_UBOOT */

     /* Set up the stack */
 stack_setup:
     ldr    r0, _TEXT_BASE        @ upper  KiB: relocated uboot
     sub    r0, r0, #CONFIG_SYS_MALLOC_LEN @ malloc area
     sub    r0, r0, #CONFIG_SYS_GBL_DATA_SIZE @ bdinfo
 #ifdef CONFIG_USE_IRQ
     sub    r0, r0, #(CONFIG_STACKSIZE_IRQ + CONFIG_STACKSIZE_FIQ)
 #endif
     sub    sp, r0, #        @ leave  words for abort-stack
     and    sp, sp, #~        @  byte alinged for (ldr/str)d

     /* Clear BSS (if any). Is below tx (watch load addr - need space) */
 clear_bss:
     ldr    r0, _bss_start        @ find start of bss segment
     ldr    r1, _bss_end        @ stop here
     mov    r2, #0x00000000        @ clear value
 clbss_l:
     str    r2, [r0]        @ clear BSS location
     cmp    r0, r1            @ are we at the end yet
     add    r0, r0, #        @ increment clear index pointer
     bne    clbss_l            @ keep clearing till at end

 #ifdef CONFIG_ARCH_MMU
     bl board_mmu_init
 #endif
     ldr    pc, _start_armboot    @ jump to C code

 _start_armboot: .word start_armboot

17. 跳入到C语言函数中start_armboot，但是这个函数在哪里？还好在书中找到了答案。uboot_IMX6_CoreC_1.3.4_for_Linux\lib_arm\board.c

 void start_armboot (void)
 {
     init_fnc_t **init_fnc_ptr;
     char *s;
 #if defined(CONFIG_VFD) || defined(CONFIG_LCD)
     unsigned long addr;
 #endif

     /* Pointer is writable since we allocated a register for it */
     gd = (gd_t*)(_armboot_start - CONFIG_SYS_MALLOC_LEN - sizeof(gd_t));
     /* compiler optimization barrier needed for GCC >= 3.4 */
     __asm__ __volatile__("": : :"memory");

     memset ((void*)gd, , sizeof (gd_t));
     gd->bd = (bd_t*)((char*)gd - sizeof(bd_t));
     memset (gd->bd, , sizeof (bd_t));

     gd->flags |= GD_FLG_RELOC;

     monitor_flash_len = _bss_start - _armboot_start;

     for (init_fnc_ptr = init_sequence; *init_fnc_ptr; ++init_fnc_ptr) {
         if ((*init_fnc_ptr)() != ) {
             hang ();
         }
     }

     /* armboot_start is defined in the board-specific linker script */
     mem_malloc_init (_armboot_start - CONFIG_SYS_MALLOC_LEN);

 #ifndef CONFIG_SYS_NO_FLASH
     /* configure available FLASH banks */
     display_flash_config (flash_init ());
 #endif /* CONFIG_SYS_NO_FLASH */

 #ifdef CONFIG_VFD
 #    ifndef PAGE_SIZE
 #      define PAGE_SIZE
 #    endif
     /*
      * reserve memory for VFD display (always full pages)
      */
     /* bss_end is defined in the board-specific linker script */
     addr = (_bss_end + (PAGE_SIZE - )) & ~(PAGE_SIZE - );
     vfd_setmem (addr);
     gd->fb_base = addr;
 #endif /* CONFIG_VFD */

 #ifdef CONFIG_LCD
     /* board init may have inited fb_base */
     if (!gd->fb_base) {
 #        ifndef PAGE_SIZE
 #          define PAGE_SIZE
 #        endif
         /*
          * reserve memory for LCD display (always full pages)
          */
         /* bss_end is defined in the board-specific linker script */
         addr = (_bss_end + (PAGE_SIZE - )) & ~(PAGE_SIZE - );
         lcd_setmem (addr);
         gd->fb_base = addr;
     }
 #endif /* CONFIG_LCD */

 #if defined(CONFIG_CMD_NAND)
     puts ("NAND:  ");
     nand_init();        /* go init the NAND */
 #endif

 #if defined(CONFIG_CMD_ONENAND)
     onenand_init();
 #endif

 #ifdef CONFIG_HAS_DATAFLASH
     AT91F_DataflashInit();
     dataflash_print_info();
 #endif

 #ifdef CONFIG_GENERIC_MMC
 #ifndef CONFIG_DIS_BOARD_INFO
     puts ("MMC:   ");
 #endif
     mmc_initialize (gd->bd);
 #endif

     /* initialize environment */
     env_relocate ();

 #ifdef CONFIG_VFD
     /* must do this after the framebuffer is allocated */
     drv_vfd_init();
 #endif /* CONFIG_VFD */

 #ifdef CONFIG_SERIAL_MULTI
     serial_initialize();
 #endif

     /* IP Address */
     gd->bd->bi_ip_addr = getenv_IPaddr ("ipaddr");

 #if defined CONFIG_SPLASH_SCREEN && defined CONFIG_VIDEO_MX5
     setup_splash_image();
 #endif

     stdio_init ();    /* get the devices list going. */

     jumptable_init ();

 #if defined(CONFIG_API)
     /* Initialize API */
     api_init ();
 #endif

     console_init_r ();    /* fully init console as a device */

 #if defined(CONFIG_ARCH_MISC_INIT)
     /* miscellaneous arch dependent initialisations */
     arch_misc_init ();
 #endif
 #if defined(CONFIG_MISC_INIT_R)
     /* miscellaneous platform dependent initialisations */
     misc_init_r ();
 #endif

     /* enable exceptions */
     enable_interrupts ();

     /* Perform network card initialisation if necessary */
 #ifdef CONFIG_DRIVER_TI_EMAC
     /* XXX: this needs to be moved to board init */
 extern void davinci_eth_set_mac_addr (const u_int8_t *addr);
     if (getenv ("ethaddr")) {
         uchar enetaddr[];
         eth_getenv_enetaddr("ethaddr", enetaddr);
         davinci_eth_set_mac_addr(enetaddr);
     }
 #endif

 #ifdef CONFIG_DRIVER_CS8900
     /* XXX: this needs to be moved to board init */
     cs8900_get_enetaddr ();
 #endif

 #if defined(CONFIG_DRIVER_SMC91111) || defined (CONFIG_DRIVER_LAN91C96)
     /* XXX: this needs to be moved to board init */
     if (getenv ("ethaddr")) {
         uchar enetaddr[];
         eth_getenv_enetaddr("ethaddr", enetaddr);
         smc_set_mac_addr(enetaddr);
     }
 #endif /* CONFIG_DRIVER_SMC91111 || CONFIG_DRIVER_LAN91C96 */

 #if defined(CONFIG_ENC28J60_ETH) && !defined(CONFIG_ETHADDR)
     extern void enc_set_mac_addr (void);
     enc_set_mac_addr ();
 #endif /* CONFIG_ENC28J60_ETH && !CONFIG_ETHADDR*/

     /* Initialize from environment */
     if ((s = getenv ("loadaddr")) != NULL) {
         load_addr = simple_strtoul (s, NULL, );
     }
 #if defined(CONFIG_CMD_NET)
     if ((s = getenv ("bootfile")) != NULL) {
         copy_filename (BootFile, s, sizeof (BootFile));
     }
 #endif

 #ifdef BOARD_LATE_INIT
     board_late_init ();
 #endif

 #ifdef CONFIG_ANDROID_RECOVERY
     check_recovery_mode();
 #endif

 #if defined(CONFIG_CMD_NET)
 #if defined(CONFIG_NET_MULTI)
 #ifndef CONFIG_DIS_BOARD_INFO
     puts ("Net:   ");
 #endif
 #endif
     eth_initialize(gd->bd);
 #if defined(CONFIG_RESET_PHY_R)
     debug ("Reset Ethernet PHY\n");
     reset_phy();
 #endif
 #endif
 #ifdef CONFIG_FASTBOOT
     check_fastboot_mode();
 #endif
     /* main_loop() can return to retry autoboot, if so just run it again. */
     for (;;) {
         main_loop ();
     }

     /* NOTREACHED - no way out of command loop except booting */
 }                            
//结束