iny6410 simple LED character device driver io driver

Step1: Driver loading function: ***_init;

This function is executed only once when driving the hardware, and its function is to initialize the hardware, such as configuring the output direction of the IO port, configuring the IO pull-up, etc. This function is passed into the module_init(***_init); function so that it is automatically executed when the driver is loaded;

Step 2: Write open, read, write, and release functions;

The purpose of these three functions is to pass in the file_operations structure; these three functions are called as excuses when the application calls the driver.

The function of open is to load the driver when writing an application; its prototype is pen(strpath, authority), such as: fd = open("/dev/led",O_RDWR); //The open function loads the driver, and the return value is a descriptor. When the return value is 0, the driver is loaded successfully.

The prototype of the Write function is: (structfile *filp, const char __user *buf, size_t count,loff_t *f_pos)   

Step 3: Assign the function in step 2 to the operations structure

struct file_operations led_fops =  

{   

    .owner = THIS_MODULE,   

    .open = led_open,   

    .read = led_read,   

    .write = led_write,   

    .release = led_release,   

};

Step4: Register the character device driver module in the ***_init function; the following is the registration LED driver function:

register_chrdev(LED_MAJOR,"led",&led_fops);

int register_chrdev(unsigned int major,const char *name,struct file_operations *fops);

If the parameter major is equal to 0, it means that the major device number dynamically allocated by the system is used; if it is not 0, it means static registration.

To unregister a character device, you can use the unregister_chrdev function.

Step 5: Unregister the character device driver module:

In led_exit (you can use any name, just pass the function name to module_exit) use unregister_chrdev(LED_MAJOR,"led"); function to unregister the driver. And assign it to module_exit(led_exit);

A living example   

1. Check the user manual

LED1, LED2, LED3, LED4 are connected to GPK4, GPK5, GPK6, GPK7 respectively

2. Check the 6410 chip manual

There are 3 more steps to follow:

1. Set GPIO to OUTPUT.

   Set GPK4, GPK5, GPK6, GPK7 to output=0001

   That is, 19:28 of GPKCON0 are configured as 0001

2. Set the GPIO data.

   Set bits 4:7 of GPKDATA to 0

3. Set GPKUP to pull up.

   Set bits 4:7 of GPKUP to 10

3. Code

led_driver.cStep1: driver loading function: ***_init;

This function is executed only once when driving the hardware, and its function is to initialize the hardware, such as configuring the output direction of the IO port, configuring the IO pull-up, etc. This function is passed into the module_init(***_init); function so that it is automatically executed when the driver is loaded;

Step 2: Write open, read, write, and release functions;

The purpose of these three functions is to pass in the file_operations structure; these three functions are called as excuses when the application calls the driver.

The function of open is to load the driver when writing an application; its prototype is pen(strpath, authority), such as: fd = open("/dev/led",O_RDWR); //The open function loads the driver, and the return value is a descriptor. When the return value is 0, the driver is loaded successfully.

The prototype of the Write function is: (structfile *filp, const char __user *buf, size_t count,loff_t *f_pos)   

Step 3: Assign the function in step 2 to the operations structure

struct file_operations led_fops =  

{   

    .owner = THIS_MODULE,   

    .open = led_open,   

    .read = led_read,   

    .write = led_write,   

    .release = led_release,   

};

Step4: Register the character device driver module in the ***_init function; the following is the registration LED driver function:

register_chrdev(LED_MAJOR,"led",&led_fops);

int register_chrdev(unsigned int major,const char *name,struct file_operations *fops);

If the parameter major is equal to 0, it means that the major device number dynamically allocated by the system is used; if it is not 0, it means static registration.

To unregister a character device, you can use the unregister_chrdev function.

Step 5: Unregister the character device driver module:

In led_exit (you can use any name, just pass the function name to module_exit) use unregister_chrdev(LED_MAJOR,"led"); function to unregister the driver. And assign it to module_exit(led_exit);

A living example   

1. Check the user manual

LED1, LED2, LED3, LED4 are connected to GPK4, GPK5, GPK6, GPK7 respectively

2. Check the 6410 chip manual

There are 3 more steps to follow:

1. Set GPIO to OUTPUT.

   Set GPK4, GPK5, GPK6, GPK7 to output=0001

   That is, 19:28 of GPKCON0 are configured as 0001

2. Set the GPIO data.

   Set bits 4:7 of GPKDATA to 0

3. Set GPKUP to pull up.

   Set bits 4:7 of GPKUP to 10

3. Code

led_driver.c

#include /*It defines the module's API, type and macros (MODULE_LICENSE, MODULE_AUTHOR, etc.). All kernel modules must include this header file. */   

    #include /*This file should be included when using kernel information priority. Priority information is generally used when using the printk function*/  

    #include     

    #include /* copy_to_user,copy_from_user */     

    #include /*readl writel*/  

    #include      

    #include       

    #include       

    #define LED_MAJOR 243  

    #define LED_ON 1  

    #define LED_OFF 0  

    #define LED_1_ON 2  

    #define LED_1_OFF 3  

    #define LED_2_ON 4  

    #define LED_2_OFF 5  

    #define LED_3_ON 6  

    #define LED_3_OFF 7  

    #define LED_4_ON 8  

    #define LED_4_OFF 9  

    static int led_open (struct inode *inode,struct file *filp)    

    {    

        unsigned tmp;       

        tmp = readl(S3C64XX_GPKCON);      

        tmp = (tmp&0x0000ffff)| 0x1111ffff;  

        writel(tmp, S3C64XX_GPKCON);     

        printk("#########open#######n");    

        return 0;    

    }    

    static int led_read (struct file *filp, char __user *buf, size_t count,loff_t *f_pos)    

    {      

        return count;    

    }    

    static int led_write (struct file *filp, const char __user *buf, size_t count,loff_t *f_pos)  

    {    

        char wbuf[10];    

        unsigned tmp;       

        if(copy_from_user(wbuf,buf,count))  

            return -EFAULT;    

            switch(wbuf[0])    

            {    

            case LED_ON:   

                    tmp = readl(S3C64XX_GPKDAT);       

                tmp &= (0x0f);       

                writel(tmp, S3C64XX_GPKDAT);  

                printk("turn on!n");      

                    break;  

            case LED_OFF:    

                tmp = readl(S3C64XX_GPKDAT);       

                tmp |= (0xf0);       

                writel(tmp, S3C64XX_GPKDAT);   

                printk("turn off!n");     

                break;             

            case LED_1_ON:    

                tmp = readl(S3C64XX_GPKDAT);       

                tmp &= (0xef);       

                writel(tmp, S3C64XX_GPKDAT);   

                printk("turn off!n");     

                break;    

            case LED_1_OFF:   

                    tmp = readl(S3C64XX_GPKDAT);       

                tmp |= (0xf0);       

                writel(tmp, S3C64XX_GPKDAT);  

                printk("turn on!n");      

                    break;    

            case LED_2_ON:    

                tmp = readl(S3C64XX_GPKDAT);       

                tmp &= (0xdf);       

                writel(tmp, S3C64XX_GPKDAT);   

                printk("turn off!n");     

                break;    

            case LED_2_OFF:   

                    tmp = readl(S3C64XX_GPKDAT);       

                tmp |= (0xf0);       

                writel(tmp, S3C64XX_GPKDAT);  

                printk("turn on!n");      

                    break;    

            case LED_3_ON:    

                tmp = readl(S3C64XX_GPKDAT);       

                tmp &= (0xbf);       

                writel(tmp, S3C64XX_GPKDAT);   

                printk("turn off!n");     

                break;    

            case LED_3_OFF:   

                    tmp = readl(S3C64XX_GPKDAT);       

                tmp |= (0xf0);       

                writel(tmp, S3C64XX_GPKDAT);  

                printk("turn on!n");      

                    break;    

            case LED_4_ON:    

                tmp = readl(S3C64XX_GPKDAT);       

                tmp &= (0x7f);       

                writel(tmp, S3C64XX_GPKDAT);   

                printk("turn off!n");     

                break;    

            case LED_4_OFF:   

                    tmp = readl(S3C64XX_GPKDAT);       

                tmp |= (0xf0);       

                writel(tmp, S3C64XX_GPKDAT);  

                printk("turn on!n");      

                    break;    

            default :    

                    break;    

            }    

         return 0;    

    }    

    int led_release (struct inode *inode, struct file *filp)    

    {    

        printk("#########release######n");    

        return 0;    

    }    

    struct file_operations led_fops =  

    {    

        .owner = THIS_MODULE,    

        .open = led_open,    

        .read = led_read,    

        .write = led_write,    

        .release = led_release,    

    };    

    int __init led_init (void)    

    {     

        int rc;    

        printk ("Test led devn");    

        rc = register_chrdev(LED_MAJOR,"led",&led_fops);   

        if (rc <0)    

        {    

            printk ("register %s char dev errorn","led");    

            return -1;    

        }    

        printk ("ok!n");    

        return 0;    

    }    

    void __exit led_exit (void)    

    {    

        unregister_chrdev(LED_MAJOR,"led");    

        printk ("module exitn");