android FireFlay开发板点亮LED驱动开发

实现功能，点亮LED，参考了网上部分代码。

 

1.在目录/src/kernel/drivers/下面建立一个文件夹testLed，并添加三个文件Makefile、mytestled.c、Kconfig。

 

Kconfig内容如下，后期编译时可以用make menuconfig命令，然后在Device Drivers --->一栏里面选择将该模块编译进去

config MYTESTLED
       tristate "My test led driver"
       help 
         Test led driver

 MakeFile内容如下：

 

obj-$(CONFIG_MYTESTLED)                   +=mytestled.o

 

 

mytestled.c内容如下:

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>

#include <linux/kernel.h>   /* printk() */
#include <linux/slab.h>   /* kmalloc() */
#include <linux/fs.h>       /* everything... */
#include <linux/errno.h>    /* error codes */
#include <linux/types.h>    /* size_t */
#include <linux/mm.h>
#include <linux/kdev_t.h>
#include <linux/cdev.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <linux/gpio.h>

static int simple_major = 199;

#define LED_ON 0x4800
#define LED_GPIO 258
#define GPIO_LOW 0
#define GPIO_HIGH 1

//LED闪烁1次
void led_on(void)

{
	printk("lesStart.....\n");

	gpio_set_value(LED_GPIO, GPIO_LOW);
	mdelay(1000);

	gpio_set_value(LED_GPIO, GPIO_HIGH);
	mdelay(1000);
}

/*
 * Open the device; in fact, there's nothing to do here.
 */
int simple_led_open(struct inode *inode, struct file *filp) {

	return 0;
}

ssize_t simple_read(struct file *file, char __user *buff, size_t count, loff_t *offp)
{
//在adb shell里面执行：cat /dev/testLed2 则会触发该函数
	//led_on();
	return 0;
}

ssize_t simple_write(struct file *file, const char __user *buff, size_t count, loff_t *offp)
{
	return 0;
}


/**
 * 内核低于2.6.36
 */
static int simple_ioctl(struct inode *inode, struct file *file,
		unsigned int cmd, unsigned long arg) {
	switch (cmd) {
	case LED_ON: {
		led_on();
		break;
	}
	default: {
		break;
	}
	}
	return 0;
}

/**
 * 内核高于2.6.36
 */
static long simple_ioctl_new(struct file *file, unsigned int cmd,
		unsigned long arg) {
	switch (cmd) {
	case LED_ON: {
		led_on();
		break;
	}
	default: {
		break;
	}
	}
	return 0;
}
static int simple_release(struct inode *node, struct file *file) {
	return 0;
}

/*
 * Set up the cdev structure for a device.
 */
static void simple_setup_cdev(struct cdev *dev, int minor,
		struct file_operations *fops) {
	int err, devno = MKDEV(simple_major, minor);

	cdev_init(dev, fops);
	dev->owner = THIS_MODULE;
	dev->ops = fops;
	//第三个参数为设备个数
	err = cdev_add(dev, devno, 1);
	/* Fail gracefully if need be */
if (err)
printk (KERN_NOTICE "Error %d adding simple%d", err, minor);
}

/*
 * Our various sub-devices.
 */
/* Device 0 uses remap_pfn_range */
static struct file_operations simple_remap_ops = { .owner = THIS_MODULE, .open =
	simple_led_open, .release = simple_release, .read = simple_read, .write =
	simple_write,
// 内核低于2.6.36则为.ioctl
//	.ioctl = simple_ioctl,
	.compat_ioctl = simple_ioctl_new };

/*
 * We export two simple devices.  There's no need for us to maintain any
 * special housekeeping info, so we just deal with raw cdevs.
 */
static struct cdev SimpleDevs;

/*
 * Module housekeeping.
 */
static struct class *my_class;
static int simple_init(void) {

int result;
//根据主设备号和次设备号创建dev_t
dev_t dev = MKDEV(simple_major, 0);

if (simple_major) {

	//如果指定了具体的主设备号，则去注册，第二个参数表示注册的此设备数量，这里只有一个led,第三个参数为设备名字/proc/devices/testLed
	result = register_chrdev_region(dev, 1, "testLed");
} else {
	//如果没有指定具体的主设备号，则自动分配。第二个参数一般为0(次设备号的基准,从第几个次设备号开始分配),第三个参数表示注册的此设备数量
	result = alloc_chrdev_region(&dev, 0, 1, "testLed");
	//获取到自动分配所得到的主设备号
	simple_major = MAJOR(dev);
}
if (result < 0) {
	//获取设备号失败
	printk(KERN_WARNING "simple: unable to get major %d\n", simple_major);
	return result;
}

if (simple_major == 0) {
	simple_major = result;
}

simple_setup_cdev(&SimpleDevs, 0, &simple_remap_ops);
printk("simple device installed, with major %d\n", simple_major);
my_class = class_create(THIS_MODULE, "testLed");
//创建/dev/testLed2
device_create(my_class, NULL, MKDEV(simple_major, 0), NULL, "testLed2");
return 0;
}

static void simple_cleanup(void) {
cdev_del(&SimpleDevs);
unregister_chrdev_region(MKDEV(simple_major, 0), 1);
device_destroy(my_class, MKDEV(simple_major, 0));
printk("simple device uninstalled\n");
}

module_init( simple_init);
module_exit( simple_cleanup);

 

 

2.在文件src/kernel/arch/arm/configs/firefly_defconfig最后增加下面一行，这样就无需用make menuconfig进行配置了

CONFIG_MYTESTLED=y

 

 

3.在文件src/kernel/drivers/Kconfig 最后增加下面一行

source "drivers/testLed/Kconfig"

 4.在文件src/kernel/drivers/Makefile最后增加下面一行

 

obj-y          += testLed/

 

 

5.重新编译kernel 即可