致遠電子IMX283A之點亮擴展板led

編譯環境：ubuntu Kylin 14.04 LTS
編譯工具：gcc-4.4.4-glibc-2.11.1-multilib-1.0_EasyARM-iMX283.tar.bz2
測試硬件：EasyARM-iMX283A AP-283Demo擴展板

1、通過AP-283Demo數據手冊查詢到要點亮的四個LED所對應的GPIO並短接擴展板的J8A與J8C管腳

2、編寫LED的驅動，驅動這裏時參照資料包裏led驅動編寫，目前只瞭解大概意思，說不出個所以然來，所以直接貼代碼：
代碼只是例程代碼複製了四份修改了下函數名

//#define LED_GPIO  MXS_PIN_TO_GPIO(PINID_LCD_D23)      //for 283 287A/B

#define LED1_GPIO   MXS_PIN_TO_GPIO(PINID_SAIF1_SDATA0)     //for 283 287A/B
#define LED2_GPIO   MXS_PIN_TO_GPIO(PINID_SAIF0_BITCLK)     //for 283 287A/B
#define LED3_GPIO   MXS_PIN_TO_GPIO(PINID_SAIF0_MCLK)       //for 283 287A/B
#define LED4_GPIO   MXS_PIN_TO_GPIO(PINID_SSP0_DATA7)       //for 283 287A/B

static int gpio_open(struct inode *inode, struct file *filp);
static int  gpio_release(struct inode *inode, struct file *filp);
ssize_t gpio_write(struct file *filp, const char __user *buf, size_t count,
                loff_t *f_pos);
static int gpio_ioctl(struct inode *inode,struct file *flip,unsigned int command,unsigned long arg);
static int gpio_init(void);
static void gpio_exit(void);

/*--------------------------------------------------------------------------------------------------------
*/
// led1 func
static int gpio_open(struct inode *inode, struct file *filp){
    gpio_request(LED1_GPIO, "imx283_led");

    return 0;
}

static int  gpio_release(struct inode *inode, struct file *filp){
    gpio_free(LED1_GPIO);
    return 0;
}


ssize_t gpio_write(struct file *filp, const char __user *buf, size_t count,loff_t *f_pos){
    char data[2];

    copy_from_user(data, buf, count);
    gpio_direction_output(LED1_GPIO, data[0]);

    return count;
}

static int gpio_ioctl(struct inode *inode,struct file *flip,unsigned int command,unsigned long arg){
    int data;

    switch (command) {
    case 0: 
        gpio_direction_output(LED1_GPIO, 0);
        break;

    case 1:
        gpio_direction_output(LED1_GPIO, 1);
        break;
    }

    return 0;
}

static struct file_operations gpio_fops1={
    .owner      = THIS_MODULE,
    .open       = gpio_open,
    .write      = gpio_write,
    .release    = gpio_release,
    .ioctl      = gpio_ioctl,
};

// led2 func
static int gpio_open2(struct inode *inode, struct file *filp){
    gpio_request(LED2_GPIO, "imx283_led");

    return 0;
}

static int  gpio_release2(struct inode *inode, struct file *filp){
    gpio_free(LED2_GPIO);
    return 0;
}


ssize_t gpio_write2(struct file *filp, const char __user *buf, size_t count,loff_t *f_pos){
    char data[2];

    copy_from_user(data, buf, count);
    gpio_direction_output(LED2_GPIO, data[0]);

    return count;
}

static int gpio_ioctl2(struct inode *inode,struct file *flip,unsigned int command,unsigned long arg){
    int data;

    switch (command) {
    case 0: 
        gpio_direction_output(LED2_GPIO, 0);
        break;

    case 1:
        gpio_direction_output(LED2_GPIO, 1);
        break;
    }

    return 0;
}

static struct file_operations gpio_fops2={
    .owner      = THIS_MODULE,
    .open       = gpio_open2,
    .write      = gpio_write2,
    .release    = gpio_release2,
    .ioctl      = gpio_ioctl2,
};

// led3 func
static int gpio_open3(struct inode *inode, struct file *filp){
    gpio_request(LED3_GPIO, "imx283_led");

    return 0;
}

static int  gpio_release3(struct inode *inode, struct file *filp){
    gpio_free(LED3_GPIO);
    return 0;
}


ssize_t gpio_write3(struct file *filp, const char __user *buf, size_t count,loff_t *f_pos){
    char data[2];

    copy_from_user(data, buf, count);
    gpio_direction_output(LED3_GPIO, data[0]);

    return count;
}

static int gpio_ioctl3(struct inode *inode,struct file *flip,unsigned int command,unsigned long arg){
    int data;

    switch (command) {
    case 0: 
        gpio_direction_output(LED3_GPIO, 0);
        break;

    case 1:
        gpio_direction_output(LED3_GPIO, 1);
        break;
    }

    return 0;
}

static struct file_operations gpio_fops3={
    .owner      = THIS_MODULE,
    .open       = gpio_open3,
    .write      = gpio_write3,
    .release    = gpio_release3,
    .ioctl      = gpio_ioctl3,
};

// led4 func
static int gpio_open4(struct inode *inode, struct file *filp){
    gpio_request(LED4_GPIO, "imx283_led");

    return 0;
}

static int  gpio_release4(struct inode *inode, struct file *filp){
    gpio_free(LED4_GPIO);
    return 0;
}


ssize_t gpio_write4(struct file *filp, const char __user *buf, size_t count,loff_t *f_pos){
    char data[2];

    copy_from_user(data, buf, count);
    gpio_direction_output(LED4_GPIO, data[0]);

    return count;
}

static int gpio_ioctl4(struct inode *inode,struct file *flip,unsigned int command,unsigned long arg){
    int data;

    switch (command) {
    case 0: 
        gpio_direction_output(LED4_GPIO, 0);
        break;

    case 1:
        gpio_direction_output(LED4_GPIO, 1);
        break;
    }

    return 0;
}

static struct file_operations gpio_fops4={
    .owner      = THIS_MODULE,
    .open       = gpio_open4,
    .write      = gpio_write4,
    .release    = gpio_release4,
    .ioctl      = gpio_ioctl4,
};

static struct miscdevice gpio_miscdev1 = {
    .minor  = MISC_DYNAMIC_MINOR,
    .name   = DEVICE_NAME1,
    .fops   = &gpio_fops1,
};  
static struct miscdevice gpio_miscdev2 = {
    .minor  = MISC_DYNAMIC_MINOR,
    .name   = DEVICE_NAME2,
    .fops   = &gpio_fops2,
};
static struct miscdevice gpio_miscdev3 = {
    .minor  = MISC_DYNAMIC_MINOR,
    .name   = DEVICE_NAME3,
    .fops   = &gpio_fops3,
};
static struct miscdevice gpio_miscdev4 = {
    .minor  = MISC_DYNAMIC_MINOR,
    .name   = DEVICE_NAME4,
    .fops   = &gpio_fops4,
};
static int __init gpio_init(void)
{

    misc_register(&gpio_miscdev1);
    misc_register(&gpio_miscdev2);
    misc_register(&gpio_miscdev3);
    misc_register(&gpio_miscdev4);

    return 0;
}

static void __exit gpio_exit(void)
{
    misc_deregister(&gpio_miscdev1);
    misc_deregister(&gpio_miscdev2);
    misc_deregister(&gpio_miscdev3);
    misc_deregister(&gpio_miscdev4);
}

module_init(gpio_init);
module_exit(gpio_exit);

MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("zhuguojun, ZhiYuan Electronics Co, Ltd.");
MODULE_DESCRIPTION("GPIO DRIVER FOR EasyARM-i.MX28xx");

3、編譯生成驅動並加載驅動，led驅動依賴gpio驅動，所以先加載gpio_driver.ko驅動，再加載編譯生成的led.ko

查看生成的設備

4、至此可以在程序中對led對應的IO進行open、write 操作

    int fd1,fd2,fd3,fd4;
    char buf[1] = {0};

    fd1 = open("/dev/imx283_led1", O_RDWR);
    fd2 = open("/dev/imx283_led2", O_RDWR);
    fd3 = open("/dev/imx283_led3", O_RDWR);
    fd4 = open("/dev/imx283_led4", O_RDWR);
    printf("fd = %d-%d-%d-%d\n",fd1,fd2,fd3,fd4);
    if (!(fd1 && fd2 && fd3 && fd4 )) {
        perror("open /dev/imx283_led*");
    }

    printf("test write....\n");
    if(fd1 && fd2 && fd3 && fd4){
        buf[0] = 0;
        write(fd1, buf, 1); 
        write(fd2, buf, 1); 
        write(fd3, buf, 1); 
        write(fd4, buf, 1); 
        while(1){
            buf[0] = 1;     //true on led1
            write(fd1, buf, 1);
            sleep(1);   

            buf[0] = 0;     //true off led1
            write(fd1, buf, 1);
            buf[0] = 1;     //rue on led2
            write(fd2, buf, 1);         
            sleep(1);       

            buf[0] = 0;     //true off led2
            write(fd2, buf, 1);
            buf[0] = 1;     //rue on led3
            write(fd3, buf, 1);         
            sleep(1);       

            buf[0] = 0;     //true off led3
            write(fd3, buf, 1);
            buf[0] = 1;     //rue on led4
            write(fd4, buf, 1);         
            sleep(1);   

            buf[0] = 0;     //rue off led4
            write(fd4, buf, 1);         
        }
    }

    printf("test ioctl..... \n");
    ioctl(fd1, 0);
    sleep(2);
    ioctl(fd1, 1);
}

5、運行程序，依次循環點亮