TQ2440开发板request_irq中断注册失败（-22）原因分析（三）

static struct s3c_irq_data init_eint[32]的注册在s3c2440_init_irq中，二s3c2440_init_irq是在哪里调用的呢？

root@ubuntu:/mnt/shared/linux-3.16.1# grep "s3c2440_init_irq" ./ -r
Binary file ./arch/arm/boot/Image matches
Binary file ./arch/arm/mach-s3c24xx/mach-nexcoder.o matches
Binary file ./arch/arm/mach-s3c24xx/built-in.o matches
./arch/arm/mach-s3c24xx/mach-mini2440.c:        .init_irq       = s3c2440_init_irq,
./arch/arm/mach-s3c24xx/mach-at2440evb.c:       .init_irq       = s3c2440_init_irq,
./arch/arm/mach-s3c24xx/mach-osiris.c:  .init_irq       = s3c2440_init_irq,
./arch/arm/mach-s3c24xx/mach-anubis.c:  .init_irq       = s3c2440_init_irq,
Binary file ./arch/arm/mach-s3c24xx/mach-mini2440.o matches
Binary file ./arch/arm/mach-s3c24xx/mach-anubis.o matches
./arch/arm/mach-s3c24xx/common.h:extern void s3c2440_init_irq(void);
Binary file ./arch/arm/mach-s3c24xx/mach-rx3715.o matches
./arch/arm/mach-s3c24xx/mach-nexcoder.c:        .init_irq       = s3c2440_init_irq,
Binary file ./arch/arm/mach-s3c24xx/mach-osiris.o matches
Binary file ./arch/arm/mach-s3c24xx/mach-at2440evb.o matches
./arch/arm/mach-s3c24xx/mach-smdk2440.c:        .init_irq       = s3c2440_init_irq,
Binary file ./arch/arm/mach-s3c24xx/mach-smdk2440.o matches
./arch/arm/mach-s3c24xx/mach-rx3715.c:  .init_irq       = s3c2440_init_irq,

结合编译方法make zImage -C ../，可以看出是在mach-smdk2440.c或者mach-mini2440.c中调用的。

从内核启动信息来看：

MINI2440: Option string mini2440=0tb
MINI2440: 't' ignored, touchscreen not compiled in
MINI2440: LCD [0:240x320] 1:800x480 2:1024x768 3:320x240
S3C2440: Initialising architecture

从这里很容易看出，s3c2440_init_irq是在./arch/arm/mach-s3c24xx/mach-mini2440.c中如下部分调用的：

MACHINE_START(MINI2440, "MINI2440")
/* Maintainer: Michel Pollet <[email protected]> */
.atag_offset = 0x100,
.map_io = mini2440_map_io,
.init_machine = mini2440_init,
.init_irq = s3c2440_init_irq,
.init_time = mini2440_init_time,
.restart = s3c244x_restart,
MACHINE_END

关于MACHINE_START、MACHINE_END的说明见如下文章

（摘自：http://blog.csdn.net/cxw3506/article/details/8475965）

在移植Linux时，有个结构体需要填写，它以MACHINE_START开始并以MACHINE_END结束，如下mini2440开发板的移植为示例

 MACHINE_START(MINI2440, "MINI2440")
     .phys_io    = S3C2410_PA_UART,
     .io_pg_offst    = (((u32)S3C24XX_VA_UART) >> 18) & 0xfffc,
     .boot_params    = S3C2410_SDRAM_PA + 0x100,
     .map_io     = mini2440_map_io,
     .init_machine   = mini2440_init,
     .init_irq   = s3c24xx_init_irq,
     .timer      = &s3c24xx_timer,
 MACHINE_END

其中MACHINE_START、MACHINE_END都是定义的宏，代码如下

 /*
  * Set of macros to define architecture features.  This is built into
  * a table by the linker.
  */
 #define MACHINE_START(_type,_name)          \
 static const struct machine_desc __mach_desc_##_type    \
  __used                         \
  __attribute__((__section__(".arch.info.init"))) = {    \
     .nr     = MACH_TYPE_##_type,        \
     .name       = _name,

 #define MACHINE_END             \
 };

由上代码可知这两个宏一起定义了一个类型为struct machine_desc的变量，结构体定义如下

 struct machine_desc {
     /*
      * Note! The first four elements are used
      * by assembler code in head.S, head-common.S
      */
     unsigned int        nr;     /* architecture number  */
     unsigned int        phys_io;    /* start of physical io */
     unsigned int        io_pg_offst;    /* byte offset for io
                          * page tabe entry  */

     const char      *name;      /* architecture name    */
     unsigned long       boot_params;    /* tagged list      */

     unsigned int        video_start;    /* start of video RAM   */
     unsigned int        video_end;  /* end of video RAM */

     unsigned int        reserve_lp0 :1; /* never has lp0    */
     unsigned int        reserve_lp1 :1; /* never has lp1    */
     unsigned int        reserve_lp2 :1; /* never has lp2    */
     unsigned int        soft_reboot :1; /* soft reboot      */
     void            (*fixup)(struct machine_desc *,
                      struct tag *, char **,
                      struct meminfo *);
     void            (*map_io)(void);/* IO mapping function  */
     void            (*init_irq)(void);
     struct sys_timer    *timer;     /* system tick timer    */
     void            (*init_machine)(void);
 };

这个类型的变量放在内核代码段.arch.info.init中，在内核运行初期，被函数lookup_machine_type（此函数用汇编实现，在汇编文件中）取出，读取流程为

Start_kernel() -> setup_arch() -> setup_machine() -> lookup_machine_type()

在函数setup_machine()中，利用这个结构体类型的变量初始化一些全局变量，以备内核运行时使用，比如

init_arch_irq = mdesc->init_irq;

       system_timer = mdesc->timer;

       init_machine = mdesc->init_machine;

 

这个结构体中，成员init_machine保存的是开发板资源注册的初始化代码，init_irq保存的是中断初始化指针，timer保存的是一个struct sys_timer类型的指针…..如果我们要给自己的开发板定制内核，那么我们必须自己实现以上成员函数，其中函数init_machine()是我们向内核传递开发板设备信息的重要的常规途径，分析mini2440开发板内核移植代码知道，在这个函数中，注册了开发板所用到的所有设备的相关硬件信息！

 static void __init mini2440_init(void)
 {
     struct mini2440_features_t features = { 0 };
     int i;

     printk(KERN_INFO "MINI2440: Option string mini2440=%s\n",
             mini2440_features_str);

     /* Parse the feature string */
     mini2440_parse_features(&features, mini2440_features_str);

     /* turn LCD on */
     s3c_gpio_cfgpin(S3C2410_GPC(0), S3C2410_GPC0_LEND);

     /* Turn the backlight early on */
     WARN_ON(gpio_request(S3C2410_GPG(4), "backlight"));
     gpio_direction_output(S3C2410_GPG(4), 1);

     /* remove pullup on optional PWM backlight -- unused on 3.5 and 7"s */
     s3c_gpio_setpull(S3C2410_GPB(1), S3C_GPIO_PULL_UP);
     s3c2410_gpio_setpin(S3C2410_GPB(1), 0);
     s3c_gpio_cfgpin(S3C2410_GPB(1), S3C2410_GPIO_INPUT);

     /* Make sure the D+ pullup pin is output */
     WARN_ON(gpio_request(S3C2410_GPC(5), "udc pup"));
     gpio_direction_output(S3C2410_GPC(5), 0);

     /* mark the key as input, without pullups (there is one on the board) */
     for (i = 0; i < ARRAY_SIZE(mini2440_buttons); i++) {
         s3c_gpio_setpull(mini2440_buttons[i].gpio, S3C_GPIO_PULL_UP);
         s3c_gpio_cfgpin(mini2440_buttons[i].gpio, S3C2410_GPIO_INPUT);
     }
     if (features.lcd_index != -1) {
         int li;

         mini2440_fb_info.displays =
             &mini2440_lcd_cfg[features.lcd_index];

         printk(KERN_INFO "MINI2440: LCD");
         for (li = 0; li < ARRAY_SIZE(mini2440_lcd_cfg); li++)
             if (li == features.lcd_index)
                 printk(" [%d:%dx%d]", li,
                     mini2440_lcd_cfg[li].width,
                     mini2440_lcd_cfg[li].height);
             else
                 printk(" %d:%dx%d", li,
                     mini2440_lcd_cfg[li].width,
                     mini2440_lcd_cfg[li].height);
         printk("\n");
         s3c24xx_fb_set_platdata(&mini2440_fb_info);
     }

     s3c24xx_udc_set_platdata(&mini2440_udc_cfg);
     s3c24xx_mci_set_platdata(&mini2440_mmc_cfg);
     s3c_nand_set_platdata(&mini2440_nand_info);
     s3c_i2c0_set_platdata(NULL);

     i2c_register_board_info(0, mini2440_i2c_devs,
                 ARRAY_SIZE(mini2440_i2c_devs));

     platform_add_devices(mini2440_devices, ARRAY_SIZE(mini2440_devices));

     if (features.count) /* the optional features */
         platform_add_devices(features.optional, features.count);

 }

那么成员函数init_machine什么时候被调用呢？

在函数setup_machine()中有一条语句init_machine = mdesc->init_machine;其中init_machine为全局函数指针变量，此变量在函数customize_machine()中被调用,代码如下所示：

 static int __init customize_machine(void)

 {

        /* customizes platform devices, or adds new ones */

        if (init_machine)

               init_machine();

        return 0;

 }

 arch_initcall(customize_machine);

在MACHINE_START与MACHINE_END之间还要填写一些参数，参照结构体注释小心填写即可，最好找个例子参考参考

到现在为止，中断的初始化算是追根到底了，但是err -22的原因仍未找到：

如果这里s3c2440_init_irq中只是将中断初始化的话，为什么将struct s3c_irq_data init_eint[32]中的EINT4-EINT7注掉，

则key.ko中申请中断正常，但是dm9000工作不正常，而不注掉，网卡工作正常，而key.ko中申请共享中断会失败？

明天继续寻找答案！

翻开电路图，可以看到DM9000网卡用到了EINT7，而key.c中用到了EINT4，而EINT4~7是共享中断线的，或许是这里的问题！