[mini2440]driver code

1.Example source code.

MINI2440&TQ2440 例子源码 https://download.csdn.net/download/bruce_iphone/5580591

Sugest: Copy the source code into kernel source directory, such as  linux-2.6.32.2/arch/arm/mach-s3c2440/.And opend with vscode. So it can easy to goto function body, easy to understand code.

2.First step, compile kernel.

cp config_mini2440_t35 .config
make zImage (Note: not bzImage, because vivi-boot use zImage, only uboot use bzImage)

error:(if use high vertion than ubuntu16.04.1（64bit）, because of Perl version high than v5.22.1)

Can't use 'defined(@array)' (Maybe you should just omit the defined()?) at kernel/timeconst.pl line 373.

Solution: This is Perl(a compiler) bug,not support grammar 'defined(@array)'. Modify line 373 "if (!defined(@val)) {" to "if (!@val) {"

3.Compile driver program.

The system default include directory is KERN_DIR\arch\arm\include\, if need to include some include file, just add in this directory.

Just input "make", so will generate *.ko file.

4.Run with system.

If compile with system. you can compile the dirver program into kernel. Or not need to start up with application program.

Add several lines int /etc/init.d/rcS, then add a file in /etc/rc.d/init.d/ whith file is run the driver program and application progam.

For example:

add lines as below in /etc/init.d/rcS

/etc/rc.d/init.d/leds start  
echo "                        " > /dev/tty1   
echo "Starting leds service..." > /dev/tty1   
echo "                        "                   
sleep 1

add leds in /etc/rc.d/init.d/

#!/bin/sh

base=led-player

# See how we were called.
case "$1" in
  start)
                /usr/bin/$base &
        ;;
  stop)
        pid=`/bin/pidof $base`
        if [ -n "$pid" ]; then
                kill -9 $pid
        fi
        ;;
esac

exit 0

5.Auto create device note.

Make sure support mdev or udev, test method as below:

Maybe need to add (I am not sure) /etc/init.d/rcS add a line command: echo /sbin/mdev > /proc/sys/kernel/hotplug.

Error 1: "error: implicit declaration of function 'class_create' " (when use new kernel that such as linux3.8 version to compile)

Solution: add "#include <linux/device.h>".

Error 2: "error: implicit declaration of function 'class_device_create' " (when use new kernel that such as linux3.8 version to compile)

Solution: Use device_create() function to instead class_device_create() function.

Base source code is: (below code is compile successful)

#include <linux/fs.h>
#include <linux/device.h>
static struct class *firstdrv_class;
static struct class_device	*firstdrv_class_dev;
int major;
static struct file_operations first_drv_fops = {
    .owner  =   THIS_MODULE,    /* 这是一个宏，推向编译模块时自动创建的__this_module变量 */   
};

static int first_drv_init(void)
{
    major = register_chrdev(0, "first_drv", &first_drv_fops); // 注册, 告诉内核
    firstdrv_class = class_create(THIS_MODULE, "firstdrv");
    firstdrv_class_dev = device_create(firstdrv_class, NULL, MKDEV(major, 0), NULL, "xyz"); /* /dev/xyz */
}
static void first_drv_exit(void)
{
	unregister_chrdev(major, "first_drv"); // 卸载
	device_unregister(firstdrv_class_dev);
	class_destroy(firstdrv_class);
}
module_init(first_drv_init);
module_exit(first_drv_exit);
MODULE_LICENSE("GPL");

Makefile is

KERN_DIR = /home/hui/linux-all/linux-2.6.32.2
all:
	make -C $(KERN_DIR) M=`pwd` modules 
clean:
	make -C $(KERN_DIR) M=`pwd` modules clean
	rm -rf modules.order
obj-m	+= first_drv.o

Application program:

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
/* firstdrvtest on 
  * firstdrvtest off
  */
int main(int argc, char **argv)
{
	int fd;
	int val = 1;
	fd = open("/dev/xyz", O_RDWR);
	if (fd < 0)
	{
		printf("can't open!\n");
	}
	if (argc != 2)
	{
		printf("Usage :\n");
		printf("%s <on|off>\n", argv[0]);
		return 0;
	}
	if (strcmp(argv[1], "on") == 0)
	{
		val  = 1;
	}
	else
	{
		val = 0;
	}
	write(fd, &val, 4);
	return 0;
}

6.run

Error:

Solution: add "MODULE_LICENSE("GPL");" in source code.

If create device note auto, will find the note already in /dev/

At lastst, you can run the application programe.

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