#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/io.h>

#define LED_MAJOR   200
#define LED_NAME    "led"

/* 寄存器物理地址 */
#define CCM_CCGR1_BASE              (0X020C406C)
#define SW_MUX_GPIO1_IO03_BASE      (0X020E0068)
#define SW_PAD_GPIO1_IO03_BASE      (0X020E02F4)
#define GPIO1_DR_BASE               (0X0209C000)
#define GPIO1_GDIR_BASE             (0X0209C004)

/* 地址映射后的虚拟地址指针 */
static void __iomem *IMX6U_CCM_CCGR1;
static void __iomem *SW_MUX_GPIO1_IO03;
static void __iomem *SW_PAD_GPIO1_IO03;
static void __iomem *GPIO1_DR;
static void __iomem *GPIO1_GDIR;

#define LEDOFF  0       /* 关闭 */
#define LEDON   1       /* 打开 */


/* LED灯打开/关闭 */
static void led_switch(u8 sta)
{
    u32 val = 0;

    if(sta == LEDON) {
        val = readl(GPIO1_DR);
        val &= ~(1 << 3);            /* bit3清零,打开LED灯 */
        writel(val, GPIO1_DR); 
    } else if(sta == LEDOFF) {
        val = readl(GPIO1_DR);
        val |= (1 << 3);            /* bit3清零,打开LED灯 */
        writel(val, GPIO1_DR);
    }
}

static int led_open(struct inode *inode, struct file *filp)
{
    return 0;
}

static int led_release(struct inode *inode, struct file *filp)
{
    return 0;
}

static ssize_t led_write(struct file *filp, const char __user *buf,
			 size_t count, loff_t *ppos)
{
    int retvalue;
    unsigned char databuf[1];

    retvalue = copy_from_user(databuf, buf, count);
    if(retvalue < 0) {
        printk("kernel write failed!\r\n");
        return -EFAULT;
    }

    /* 判断是开灯还是关灯 */
    led_switch(databuf[0]);

    return 0;
}            


/* 字符设备操作集 */
static const struct file_operations led_fops = {
   	.owner	= THIS_MODULE,
	.write	= led_write,
	.open	= led_open,
	.release= led_release,
};


/* 入口 */
static int __init led_init(void)
{
    int ret = 0;
    unsigned int val = 0;
    /* 1,初始化LED灯,地址映射 */
    IMX6U_CCM_CCGR1 = ioremap(CCM_CCGR1_BASE, 4);
    SW_MUX_GPIO1_IO03 = ioremap(SW_MUX_GPIO1_IO03_BASE, 4);
    SW_PAD_GPIO1_IO03 = ioremap(SW_PAD_GPIO1_IO03_BASE, 4);
    GPIO1_DR = ioremap(GPIO1_DR_BASE, 4);
    GPIO1_GDIR = ioremap(GPIO1_GDIR_BASE, 4);

    /* 2,初始化 */
    val = readl(IMX6U_CCM_CCGR1);
    val &= ~(3 << 26);  /* 先清除以前的配置bit26,27 */
    val |= 3 << 26;     /* bit26,27置1 */
    writel(val, IMX6U_CCM_CCGR1);
 
    writel(0x5, SW_MUX_GPIO1_IO03);     /* 设置复用 */
    writel(0X10B0, SW_PAD_GPIO1_IO03);  /* 设置电气属性 */

    val = readl(GPIO1_GDIR);
    val |= 1 << 3;              /* bit3置1,设置为输出 */
    writel(val, GPIO1_GDIR);

    val = readl(GPIO1_DR);
    val |= (1 << 3);            /* bit3置1,关闭LED灯 */
    writel(val, GPIO1_DR);


    /* 1,注册字符设备 */
    ret = register_chrdev(LED_MAJOR, LED_NAME, &led_fops);
    if(ret < 0) {
        printk("register chardev failed!\r\n");
        return -EIO;
    }

    printk("led_init\r\n");
    return 0;
}

/* 出口 */
static void __exit led_exit(void)
{
    unsigned int val = 0;
    val = readl(GPIO1_DR);
    val |= (1 << 3);            /* bit3清零,打开LED灯 */
    writel(val, GPIO1_DR);

    /* 1,取消地址映射 */
    iounmap(IMX6U_CCM_CCGR1);
    iounmap(SW_MUX_GPIO1_IO03);
    iounmap(SW_PAD_GPIO1_IO03);
    iounmap(GPIO1_DR);
    iounmap(GPIO1_GDIR);

    /* 注销字符设备 */
    unregister_chrdev(LED_MAJOR, LED_NAME);
    printk("led_exit\r\n");
}

/*注册驱动加载和卸载*/
module_init(led_init);
module_exit(led_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("zuozhongkai");