4412 GPIO初始化

一、GPIO的初始化

• 在内核源码目录下使用命令“ls drivers/gpio/*.o”，可以看到“gpioexynos4”被编译进了内核.通过搜索*.o文件，可以知道内核编译内哪些文件。针对的看可以简化很多。
– 生成.o文件代表最终被编译进了内核
– 除了menuconfig配置文件，还可以通过.o文件来判定该文件是否编译进了

ls drivers/gpio/*.o

 

内核

• 在“gpio-exynos4.c”文件最下面一行
– core_initcall(exynos4_gpiolib_init);
– core_initcall代表在linux初始化过程中会调用
– 初始化函数是在源码目录下“include/linux/init.h”文件中定义的，该头文件中定义了一系列的初始化函数，在linux启动的过程中会按等级

/*
 * A "pure" initcall has no dependencies on anything else, and purely
 * initializes variables that couldn't be statically initialized.
 *
 * This only exists for built-in code, not for modules.
 */
#define pure_initcall(fn)               __define_initcall("0",fn,0)

#define core_initcall(fn)               __define_initcall("1",fn,1)
#define core_initcall_sync(fn)          __define_initcall("1s",fn,1s)
#define postcore_initcall(fn)           __define_initcall("2",fn,2)
#define postcore_initcall_sync(fn)      __define_initcall("2s",fn,2s)
#define arch_initcall(fn)               __define_initcall("3",fn,3)
#define arch_initcall_sync(fn)          __define_initcall("3s",fn,3s)
#define subsys_initcall(fn)             __define_initcall("4",fn,4)
#define subsys_initcall_sync(fn)        __define_initcall("4s",fn,4s)
#define fs_initcall(fn)                 __define_initcall("5",fn,5)
#define fs_initcall_sync(fn)            __define_initcall("5s",fn,5s)
#define rootfs_initcall(fn)             __define_initcall("rootfs",fn,rootfs)
#define device_initcall(fn)             __define_initcall("6",fn,6)

init.h文件相关部分

• 初始化函数调用了“exynos4_gpiolib_init”
• 通过软件source insight查找到exynos4_gpiolib_init函数的定义
• 在该函数中引用了chip = exynos4_gpio_common_4bit结构体
• 查找到结构体exynos4_gpio_common_4bit
• 可以看到结构体中有S5P_VA_XXXX的基地址定义，VA一般用来代表虚拟地址

以有带有label= "GPL2"的结构体为例

 

 

结构体exynos4_gpio_common_4bit

• .base = (S5P_VA_GPIO2 + 0x100)
– 表示偏移地址和虚拟地址相加
• .eint_offset = 0x20
– 表示中断部分，介绍中断的时候再讲（IO口可以配置为中断模式）
• .group = 22
– 给GPIO分组
• chip.base = EXYNOS4_GPL2(0),
– 宏定义EXYNOS4_GPL2(0)赋值给初始化函数
• chip.ngpio = EXYNOS4_GPIO_L2_NR
– 表示这一小组中有几个GPIO
• chip.label = "GPL2",
– 程序员需要关心的标志

• 宏定义EXYNOS4_GPL2(0)分析
– EXYNOS4_GPL2(_nr) (EXYNOS4_GPIO_L2_START + (_nr))
– 枚举GPIO
– EXYNOS4_GPIO_L2_START= EXYNOS4_GPIO_NEXT(EXYNOS4_GPIO_L1)
– EXYNOS4_GPIO_NEXT宏定义
– #define EXYNOS4_GPIO_NEXT(__gpio) \ ((__gpio##_START) + (__gpio##_NR)
+ CONFIG_S3C_GPIO_SPACE + 1)
• GPIO的数量EXYNOS4_GPIO_L2_NR
– 可以通过手册查到
• S5P_VA_GPIO2

虚拟地址

• 查找S5P_VA_GPIO2宏定义，可以看到所有的GPIO被分为4个bank，这
个和datasheet上面是一致的。
– S5P_VA_GPIO1
– S5P_VA_GPIO2 S3C_ADDR(0x02240000)
– S5P_VA_GPIO3
– S5P_VA_GPIO4
• 查找到S3C_ADDR宏定义
– #define S3C_ADDR(x) (S3C_ADDR_BASE + (x))
• 查找到S3C_ADDR_BASE宏定义，这是一个虚拟地址，可以看出，地址
范围超出了1G或者2G内存的范围
– #define S3C_ADDR_BASE 0xF6000000

虚拟地址和物理地址映射

– 虚拟地址一般很好查找，一般在平台相关gpio的文件中就可以找到宏定义
• 在source insight中搜索关键字“S5P_VA_GPIO2”，看看那里用到了这个宏定义。搜索时间会比较长，1-5分钟吧。
• 搜索出来之后，可以看到除了gpio-exynos4.c文件中使用，cpu-exynos中也使用了，这是一个平台文件

 

• 结构体解释
– .virtual = (unsigned long)S5P_VA_GPIO2,表示虚拟地址

– .pfn = __phys_to_pfn(EXYNOS4_PA_GPIO2),表示物理地址

– .length = SZ_4K,表示映射的宽度

– .type = MT_DEVICE,

• 查找到宏定义EXYNOS4_PA_GPIO2

#define EXYNOS4_PA_GPIO2　　0x11000000

这个物理地址0x11000000就是

 

• 初始化过程简单描述
– 平台文件分别定义好物理地址和虚拟地址
– 物理地址和虚拟地址之间映射
• 在初始化中，引入了程序员需要使用的GPIO宏定义，并将宏定义装入chip结构体中

 

GPIO的调用函数

• 例如头文件gpio-cfg.h中s3c_gpio_cfgpin函数。这个函数是给GPIO做配置，第一个参数是宏EXYNOS4_GPL2(0)，第二个是配置的状态参数
– 配置头文件在arm/arm/plat-samsung/include/plat/gpio-cfg.h
• 查找该函数，可以看到进入函数就会调用chip结构体
– s3c_gpiolib_getchip，这个函数通过pin调用之后，会返回s3c_gpios[chip] 的参数
– exynos4_gpio_common_4bit[]和s3c_gpios都是结构体s3c_gpio_chip类型的数据
– 然后计算偏移地址等等一系列操作，这一部分是linux内核以及三星平台完成的，具体细节不用管。

• 也就是我们控制GPIO的时候，可以通过GPIO的一些处理函数加上类似EXYNOS4_GPL2(0)的宏定义，就可以操作GPIO
• 后面再具体介绍GPIO操作中，常用函数的使用

• 不是说好的分页大小要一样，怎么GPIO经过mmu处理的时候，又有SZ_256又有SZ_4K？
– 实际上CPU查找地址的时候，仍旧是通过内存。mmu本身不保存具体的数据，主要是提供一个虚拟地址和物理地址的表格，表格中还有字段的长度。这个分页和mmu没什么关系，是CPU内存以及物理地址之间通信使用
的概念。这个只是一个抽象的概念，理解mmu只是一个表格，CPU对GPIO的操作就很好理解了。

常见问题

• 内部寄存器不是很快么，CPU为什么不直接读取？
– 内部寄存器是很快，但是相对于CPU还是非常慢。CPU处理数据是将内存中一大段一大段处理，如果单个的读取内部寄存器的值，对CPU是极大的浪费。把内部寄存器也看成“特殊的物理地址”即可。
• 只讲了虚拟地址和物理地址对应数组，怎么没介绍哪里调用了？
– 大家可以看一下函数ioremap，linux会调用这个函数来实现gpio的映射关系
– 今天讲的已经够多够深入了，大家只要能够理解这么一层意思就可以了，这个东西对我们实际写驱动的帮助其实不是那么大！
• 如果我还是理解不了“对宏定义EXYNOS4_GPL2(0)的操作就是对4412芯片管脚AC21寄存器的操作”，怎么办？
– 记住这个结论，能够将宏变量EXYNOS4_GPL2(0)和GPL这一组GPIO的第0位寄存器联想起来。
– 后面跟着我依葫芦画瓢，不影响大家实际写程序，有兴趣再回过头理解

二、LED驱动

原理简单介绍

• 三极管（NPN锗管）
– “电流控制电流源”
– 三极端CE间的电阻可变，可以把Rce看成一个可调电阻，可调电阻的变量是电源
• IO管脚拉高之后，BE之间达到一定电流，可变电阻Rce就从无限大降低到大概几百欧姆。
– 高电平灯亮，低电平灯灭

头文件

• Linux中申请GPIO的头文件
– include/linux/gpio.h
• 三星平台的GPIO配置函数头文件

– arch/arm/plat-samsung/include/plat/gpio-cfg.h
– 包括三星所有处理器的配置函数
• 三星平台EXYNOS系列平台，GPIO配置参数宏定义头文件
– arch/arm/mach-exynos/include/mach/gpio.h
– GPIO管脚拉高拉低配置参数等等
– 配置参数的宏定义应该在arch/arm/plat-samsung/include/plat/gpio-cfg.h文件中
• 三星平台4412平台，GPIO宏定义头文件。已经包含在头文件gpio.h中
– arch/arm/mach-exynos/include/mach/gpio-exynos4.h
– 包括4412处理器所有的GPIO的宏定义

#include 
#include 

/* device register header file, include device and driver struct
 * register and remove function */
#include 
/* register misc device header file */
#include 
/* register deivce node file operations struct */
#include 

/* linux gpio header file */
#include 
/* samsung gpio config file */
#include 
/* exynos gpio config header file */
#include 
/* 4412 gpio header file */
#include 

#define DRIVER_NAME "hello_ctl"
#define DEVICE_NAME "hello_ctl"

MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("TOPEET");

static int hello_open(struct inode *inode, struct file *file)
{
        printk(KERN_EMERG "hello open\n");
        return 0;
}

static int hello_release(struct inode *inode, struct file *file)
{
        printk(KERN_EMERG "hello release\n");
        return 0;
}

static long hello_ioctl(struct file *file, unsigned int cmd ,unsigned long arg)
{
        printk(KERN_EMERG "cmd is %u, arg is %lu\n", cmd, arg);

        if(cmd > 1 || arg > 1) {
                printk(KERN_EMERG "cmd and arg is 0 or 1\n");
                return 0;
        }

        gpio_set_value(EXYNOS4_GPL2(0), cmd);

        return 0;
}

static struct file_operations  hello_ops = {
        .owner   = THIS_MODULE,
        .open    = hello_open,
        .release = hello_release,
        .unlocked_ioctl = hello_ioctl,
};

static struct miscdevice hello_dev = {
        .minor = MISC_DYNAMIC_MINOR,
        .name  = DEVICE_NAME,
        .fops  = &hello_ops,
};

static int hello_probe(struct platform_device *pdv)
{
        int ret;
        printk(KERN_EMERG "\tinitialized\n");

        /* set up gpio */
        ret = gpio_request(EXYNOS4_GPL2(0), "LEDS");
        if(ret < 0) {
                printk(KERN_EMERG "gpio_request EXYNOS4_GPL2(0) failed\n");
                return ret;
        }

        s3c_gpio_cfgpin(EXYNOS4_GPL2(0), S3C_GPIO_OUTPUT);

        gpio_set_value(EXYNOS4_GPL2(0), 0);

        /* register */
        misc_register(&hello_dev);

        return 0;
}

static int hello_remove(struct platform_device *pdv)
{
        printk(KERN_EMERG "\tremove\n");
        misc_deregister(&hello_dev);
        return 0;
}

static void hello_shutdown(struct platform_device *pdv)
{

}

static int hello_suspend(struct platform_device *pdv, pm_message_t state)
{
        return 0;
}

static int hello_resume(struct platform_device *pdv)
{
        return 0;
}

struct platform_driver hello_driver = {
        .probe    = hello_probe,
        .remove   = hello_remove,
        .shutdown = hello_shutdown,
        .suspend  = hello_suspend,
        .resume   = hello_resume,
        .driver = {
                .name  = DRIVER_NAME,
                .owner = THIS_MODULE,
        }
};

static int hello_init(void)
{
        int DriverState;

    printk(KERN_EMERG "Hello world enter!\n");
        DriverState = platform_driver_register(&hello_driver);

        printk(KERN_EMERG "\tDriverState is %d\n", DriverState);
    return 0;
}

static void hello_exit(void)
{
    printk(KERN_EMERG "Hello world exit!\n");
        platform_driver_unregister(&hello_driver);
}

module_init(hello_init);
module_exit(hello_exit);

leds_module

 

linuxGPIO申请函数和赋值函数

– gpio_request
– gpio_set_value
• 三星平台配置GPIO函数
– s3c_gpio_cfgpin
• GPIO配置输出模式的宏变量
– S3C_GPIO_OUTPUT
• 使用这些函数和宏变量，将devicenode_linux_module.c改写为leds.c

• 将内核中的LED驱动去掉，重新编译内核，烧写到开发板。
• 将invoke_hello.c改写为invoke_leds.c
• 简单修改编译文件，编译
– arm-none-linux-gnueabi-gcc -o invoke_leds invoke_leds.c -static

 

在使用invoke_leds时，内需需要重新编译，去掉led的模块。

[root@iTOP-4412]# insmod hello.ko                                                                          
[  149.082155] Hello world enter!
[  149.084082]  initialized
[  149.089124]  DriverState is 0

[root@iTOP-4412]# ls /dev/h*                                                                               
/dev/hello_ctl

[root@iTOP-4412]# ./invok_leds                                                                             
[  342.437287] hello open
[  342.438727] cmd is 1, arg is 1
APP open /dev/hello_ctl success
[  345.441525] cmd is 0, arg is 1
[  348.443325] cmd is 1, arg is 1
[  351.445052] cmd is 0, arg is 1
[  351.446632] hello release

 

三、GPIO复用和程序简单分析

 去掉占用GPIO的驱动

去掉占用调用的GPIO驱动，包括leds，buzzer，camera ov5640，WIFI mt6620

VIDEO_OV5640
– Device Drivers
– Multimedia support(MEDIA_SUPPORT [=y])
– Video capture adapters(VIDEO_CAPTURE_DRIVERS [=y])（去掉）

MTK_COMBO_CHIP_MT6620
– Device Drivers
– MediaTek Connectivity Combo Chip Config
– MediaTek Connectivity Combo Chip Support (MTK_COMBO [=y])（去掉）
– Select Chip ( [=y])

Enable LEDS config
– Device Drivers
– Character devices
– Enable LEDS config

Enable BUZZER config
– Device Drivers
– Character devices
– Enable BUZZER config

static int led_gpios[] = {
    EXYNOS4_GPL2(0), EXYNOS4_GPK(1),　　　　/* Led IO 2个 */
    EXYNOS4_GPD0(0),　　　　　　　　　　　　　 /* BUZZER IO 1个 */

    EXYNOS4_GPX1(0), EXYNOS4_GPX1(3),EXYNOS4_GPX1(5),EXYNOS4_GPX1(6),　　　　/* 矩阵健盘8个 */
    EXYNOS4_GPX3(0),EXYNOS4_GPX2(6),EXYNOS4_GPX2(7),EXYNOS4_GPX3(5),

    EXYNOS4212_GPJ1(3),EXYNOS4_GPL0(1),EXYNOS4_GPL0(3),EXYNOS4212_GPJ1(0),　　　　　　/* 摄像头14个 */
    EXYNOS4212_GPJ1(2),EXYNOS4212_GPJ1(1),EXYNOS4212_GPJ0(7),EXYNOS4212_GPJ0(6),
    EXYNOS4212_GPJ0(5),EXYNOS4212_GPJ0(4),EXYNOS4212_GPJ0(0),EXYNOS4212_GPJ0(3),
　　 EXYNOS4212_GPJ0(1),EXYNOS4212_GPJ0(2),

    EXYNOS4_GPK3(6),EXYNOS4_GPK3(1),EXYNOS4_GPK3(4),EXYNOS4_GPK3(0),　　　　　　/* WIFI 7个 */
    EXYNOS4_GPK3(3),EXYNOS4_GPK3(5),EXYNOS4_GPC1(1),
};

 

编译简单程序测试

• 将leds.c修改为gpios.c，可以控制32个GPIO
• 修改Makefile文件
• 将invoke_leds.c修改为invoke_gpios.c
• 编译应用
– arm-none-linux-gnueabi-gcc -o invoke_gpios invoke_gpios.c -static
• 在开发板上加载测试

#include 
#include 

/*驱动注册的头文件，包含驱动的结构体和注册和卸载的函数*/
#include 
/*注册杂项设备头文件*/
#include 
/*注册设备节点的文件结构体*/
#include 

/*Linux中申请GPIO的头文件*/
#include 
/*三星平台的GPIO配置函数头文件*/
/*三星平台EXYNOS系列平台，GPIO配置参数宏定义头文件*/
#include 
#include 
/*三星平台4412平台，GPIO宏定义头文件*/
#include 

#define DRIVER_NAME "hello_ctl"
#define DEVICE_NAME "hello_gpio"


MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("TOPEET");




/*led的两个IO，网络是KP_COL0，VDD50_EN*/
/*蜂鸣器的1个IO，网络是MOTOR_PWM*/

/*矩阵键盘的8个IO，网络是CHG_FLT，HOOK_DET，CHG_UOK，XEINT14_BAK，
GM_INT1，6260_GPIO1，CHG_COK，XEINT29/KP_ROW13/ALV_DBG25*/

/*摄像头的14个IO，网络是CAM_MCLK，CAM2M_RST，CAM2M_PWDN，
CAM_D5，CAM_D7，CAM_D6，CAM_D4，CAM_D3，CAM_D2，CAM_D1，
CAM_PCLK，CAM_D0，CAM_VSYNC，CAM_HREF。
I2C_SDA7，I2C_SCL7也是可以设置为GPIO，不过总线一般不要去动它*/

/*WIFI模块的7个IO，WIFI_D3，WIFI_CMD，WIFI_D1，WIFI_CLK，WIFI_D0，WIFI_D2，GPC1_1*/
/*串口RX和TX等也是可以设置为GPIO，一般不要动它*/

/*数组中有32个引出到端子或者模块的IO，还有类似sd卡等也是可以作为GPIO，
其它引到连接器但是没有使用的GPIO等等*/
/*SCP管脚编号和POP的稍微有点不同，下面是SCP的*/
static int led_gpios[] = {
    EXYNOS4_GPL2(0),EXYNOS4_GPK1(1),
    EXYNOS4_GPD0(0),
    
    EXYNOS4_GPX1(0),EXYNOS4_GPX1(3),EXYNOS4_GPX1(5),EXYNOS4_GPX1(6),
    EXYNOS4_GPX3(0),EXYNOS4_GPX2(6),EXYNOS4_GPX2(7),EXYNOS4_GPX3(5),
    
    EXYNOS4212_GPJ1(3),EXYNOS4_GPL0(1),EXYNOS4_GPL0(3),EXYNOS4212_GPJ1(0),
    EXYNOS4212_GPJ1(2),EXYNOS4212_GPJ1(1),EXYNOS4212_GPJ0(7),EXYNOS4212_GPJ0(6),
    EXYNOS4212_GPJ0(5),EXYNOS4212_GPJ0(4),EXYNOS4212_GPJ0(0),EXYNOS4212_GPJ0(3),
    EXYNOS4212_GPJ0(1),EXYNOS4212_GPJ0(2),
    
    EXYNOS4_GPK3(6),EXYNOS4_GPK3(1),EXYNOS4_GPK3(4),EXYNOS4_GPK3(0),
    EXYNOS4_GPK3(3),EXYNOS4_GPK3(5),EXYNOS4_GPC1(1),
};

#define LED_NUM        ARRAY_SIZE(led_gpios)


static long hello_ioctl( struct file *files, unsigned int cmd, unsigned long arg){
    printk("cmd is %d,arg is %d\n",cmd,arg);
    
    switch(cmd)
    {
        case 0:
        case 1:
            if (arg > LED_NUM) {
                return -EINVAL;
            }

            gpio_set_value(led_gpios[arg], cmd);
            break;

        default:
            return -EINVAL;
    }
    
    gpio_set_value(led_gpios[2], 0);
    
    return 0;
}

static int hello_release(struct inode *inode, struct file *file){
    printk(KERN_EMERG "hello release\n");
    return 0;
}

static int hello_open(struct inode *inode, struct file *file){
    printk(KERN_EMERG "hello open\n");
    return 0;
}

static struct file_operations hello_ops = {
    .owner = THIS_MODULE,
    .open = hello_open,
    .release = hello_release,
    .unlocked_ioctl = hello_ioctl,
};

static  struct miscdevice hello_dev = {
    .minor = MISC_DYNAMIC_MINOR,
    .name = DEVICE_NAME,
    .fops = &hello_ops,
};


static int hello_probe(struct platform_device *pdv){
    int ret,i;
    
    printk(KERN_EMERG "\tinitialized\n");
    
    for(i=0; i)
    {
        ret = gpio_request(led_gpios[i], "LED");
        if (ret) {
            printk("%s: request GPIO %d for LED failed, ret = %d\n", DRIVER_NAME,
                    i, ret);
            }
        else{
            s3c_gpio_cfgpin(led_gpios[i], S3C_GPIO_OUTPUT);
            gpio_set_value(led_gpios[i], 1);            
        }
    }

    gpio_set_value(led_gpios[2], 0);
    
    misc_register(&hello_dev);
    if(ret<0)
    {
        printk("leds:register device failed!\n");
        goto exit;
    }
    return 0;

exit:
    misc_deregister(&hello_dev);
    return ret;
    return 0;
}

static int hello_remove(struct platform_device *pdv){
    int i;
    
    printk(KERN_EMERG "\tremove\n");
    
    for(i=0; i)
    {
        gpio_free(led_gpios[i]);
    }
    
    misc_deregister(&hello_dev);
    return 0;
}

static void hello_shutdown(struct platform_device *pdv){
    
    ;
}

static int hello_suspend(struct platform_device *pdv,pm_message_t pmt){
    
    return 0;
}

static int hello_resume(struct platform_device *pdv){
    
    return 0;
}

struct platform_driver hello_driver = {
    .probe = hello_probe,
    .remove = hello_remove,
    .shutdown = hello_shutdown,
    .suspend = hello_suspend,
    .resume = hello_resume,
    .driver = {
        .name = DRIVER_NAME,
        .owner = THIS_MODULE,
    }
};


static int hello_init(void)

gpios.c

invok_gpios.c

#include 

#include 
#include 
#include 
#include 
#include 

#include <string.h>

#define GPIOS 32


int main(int argc , char **argv){
    int fd,i,cmd=2;
    char *hello_node = "/dev/hello_gpio";
    char *cmd0 = "0"; 
    char *cmd1 = "1";
    
    printf("argv[0] is %s;argv[1] is %s;",argv[0],argv[1]);
    
    if(strcmp(argv[1], cmd0) == 0){
        cmd = 0;
        printf("cmd is 0!\n");
    }
    if(strcmp(argv[1], cmd1) == 0){
        cmd = 1;
        printf("cmd is 1!\n");
    }
    
/*O_RDWR只读打开,O_NDELAY非阻塞方式*/    
    if((fd = open(hello_node,O_RDWR|O_NDELAY))<0){
        printf("APP open %s failed!\n",hello_node);
    }
    else{
        printf("APP open %s success!\n",hello_node);
        for(i=0;i){
            ioctl(fd,cmd,i);
            printf("APP ioctl %s ,cmd is %d,i is %d!\n",hello_node,cmd,i);
        }
    }
    
    close(fd);
}

invok_gpios

 

字符类GPIOS，LED驱动编写

字符驱动程序：

#include 
#include 

/* define module_param module_param_array header file */
#include 
/* define perm's head file*/
#include 
/* char device register head file */
#include 
/* MKDEV change device ID type */
#include 
/* define char device struct */
#include 
/* define memroy sapce */
#include 

/* include device_create class file */
#include 

#include 
#include 
#include 
#include 

#define DEVICE_NAME "chardevnode"
#define DEVICE_MINOR_NUM 2
#define DEV_MAJOR 0
#define DEV_MINOR 0
#define REGDEV_SIZE 3000

MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("TOPEET");

int numdev_major = DEV_MAJOR;
int numdev_minor = DEV_MINOR;

/* input major device ID */
module_param(numdev_major, int, S_IRUSR);
/* input minor device ID */
module_param(numdev_minor, int, S_IRUSR);

static struct class *my_class;

struct reg_dev {
    char *data;
    unsigned long size;
    struct cdev cdev;
};
struct reg_dev *my_devices;

/* open */
static int chardevnode_open(struct inode *inode, struct file *file)
{
    printk(KERN_EMERG "chardevnode open is success!\n");
    return 0;
}

/* close */
static int chardevnode_release(struct inode *indoe, struct file *file)
{
    printk(KERN_EMERG "chardevnode release is success!\n");
    return 0;
}

/* io control */
static long chardevnode_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    printk(KERN_EMERG "chardevnode release is success!cmd is %d,arg is %d\n", cmd, arg);

    if(cmd >1 || arg> 1) {
        printk(KERN_EMERG "cmd and arg is 0 or 1");
        return 0;
    }
    switch(arg) {
        case 0:
            gpio_set_value(EXYNOS4_GPL2(0), cmd);
            break;
        case 1:
            gpio_set_value(EXYNOS4_GPK1(1), cmd);
            break;
        default:
            printk(KERN_EMERG "cmd and arg is 0 or 1");
            break;
    }

    return 0;
}

/* read */
static ssize_t chardevnode_read(struct file *file, char __user *buf, size_t size, loff_t *f_ops)
{
    return 0;
}

/* write */
static ssize_t chardevnode_write(struct file *file, const char __user *buf, size_t size, loff_t *ops)
{
    return 0;
}

/* lseek */
static loff_t chardevnode_llseek(struct file *file, loff_t offset, int whence)
{
    return 0;
}

struct file_operations my_fops = {
    .owner = THIS_MODULE,
    .open  = chardevnode_open,
    .release = chardevnode_release,
    .unlocked_ioctl = chardevnode_ioctl,
    .read = chardevnode_read,
    .write = chardevnode_write,
    .llseek = chardevnode_llseek,
};

/* GPL2_0 */
static int led1_init(void)
{
    int ret;
    printk(KERN_EMERG "Gpio led 1 init\n");

    ret = gpio_request(EXYNOS4_GPL2(0), "LEDS");
    if(ret < 0) {
        printk(KERN_EMERG "gpio_request EXYNOS4_GPL2(0) failed\n");
        return ret;
    }

    s3c_gpio_cfgpin(EXYNOS4_GPL2(0), S3C_GPIO_OUTPUT);

    gpio_set_value(EXYNOS4_GPL2(0), 0);

    return 0; 
}

/* GPK1_1 */
static int led2_init(void)
{
    int ret;
    printk(KERN_EMERG "GPIO led 2 init\n");

    ret = gpio_request(EXYNOS4_GPK1(1), "LEDS2");
    if(ret < 0) {
        printk(KERN_EMERG "gpio_request EXYNOS4_GPK1(1) fialed\n");
        return ret;
    }
    s3c_gpio_cfgpin(EXYNOS4_GPK1(1), S3C_GPIO_OUTPUT);

    gpio_set_value(EXYNOS4_GPK1(1), 0);

    return 0;
}

static void reg_init_cdev(struct reg_dev *dev, int index)
{
    int err;
    int devno = MKDEV(numdev_major, numdev_minor+index);

    cdev_init(&dev->cdev, &my_fops);
    dev->cdev.owner = THIS_MODULE;
    dev->cdev.ops = &my_fops;

    err = cdev_add(&dev->cdev, devno, 1);
    if(err) {
        printk(KERN_EMERG "cdev_add %d is fail! %d\n", index, err);
    } else {
        printk(KERN_EMERG "cdev_add %d is success!\n", (numdev_minor+index));
    }
}

static int hello_init(void)
{
    int ret, i;
    dev_t num_dev;
    
    printk(KERN_EMERG "numdev_major is %d!\n", numdev_major);
    printk(KERN_EMERG "numdev_minor is %d!\n", numdev_minor);

    if(numdev_major) {
        num_dev = MKDEV(numdev_major, numdev_minor);
        ret = alloc_chrdev_region(&num_dev, numdev_minor, DEVICE_MINOR_NUM, DEVICE_NAME);
    } else {
        ret = alloc_chrdev_region(&num_dev, numdev_minor, DEVICE_MINOR_NUM, DEVICE_NAME);
        numdev_major = MAJOR(num_dev);
        printk(KERN_EMERG "register req major number is %d\n", numdev_major);
    }

    if(ret < 0) {
        printk(KERN_EMERG "register_chrdev_region req %d is failed\n", numdev_major);
        unregister_chrdev_region(num_dev, DEVICE_MINOR_NUM);
        return ret;
    }

    my_class = class_create(THIS_MODULE, DEVICE_NAME);    
    my_devices = kmalloc(DEVICE_MINOR_NUM*sizeof(struct reg_dev), GFP_KERNEL);
    if(!my_devices) {
        ret = -ENOMEM;
        printk(KERN_EMERG "kmalloc fialed!\n");
        goto fail;
    }
    memset(my_devices, 0, DEVICE_MINOR_NUM*sizeof(struct reg_dev));
    for(i=0;i) {
        my_devices[i].data = kmalloc(REGDEV_SIZE, GFP_KERNEL);        
        memset(my_devices[i].data, 0, REGDEV_SIZE);        /* data address */
        /* register device to system */
        reg_init_cdev(&my_devices[i], i);
        /* create device node */
        device_create(my_class, NULL, MKDEV(numdev_major, numdev_minor+i), "NULL", DEVICE_NAME"%d", i);
    }

    led1_init();
    led2_init();
    printk(KERN_EMERG "Hello World enter!\n");
    return 0;

fail:
    unregister_chrdev_region(num_dev, DEVICE_MINOR_NUM);
    return ret;
}

static void hello_exit(void)
{
    int i;
    dev_t num_dev = MKDEV(numdev_major, numdev_minor);
    printk(KERN_EMERG "Hello World exit!\n");
    for(i=0;i) {
        cdev_del(&my_devices[i].cdev);
        /* release memory*/
        device_destroy(my_class, MKDEV(numdev_major, numdev_minor+i));
    }
    
    /* release my class*/
    class_destroy(my_class);
    /* release kfre */
    kfree(my_devices);
    unregister_chrdev_region(num_dev, DEVICE_MINOR_NUM);
}

module_init(hello_init);
module_exit(hello_exit);

char_driver_leds.c

然后是应用程序：

#include 
#include 
#include 
#include 
#include 
#include 
#include 

int main(int argc, char *argv[])
{
        int fd0, fd1;
        char *hello_node0 = "/dev/chardevnode0";
        char *hello_node1 = "/dev/chardevnode1";
        if(argc > 2) {
                printf("please input cmd and arg\n");
        }
        /* O_RDWR只读打开, O_NDELAY非阻塞方式 */
        fd0 = open(hello_node0, O_RDWR|O_NDELAY);
        if(fd0 < 0) {
                printf("APP open %s failed\n", hello_node0);
                exit(EXIT_FAILURE);
        } else {
                printf("APP open %s success\n", hello_node0);
                ioctl(fd0, atoi(argv[1]), atoi(argv[2]));
        }
        /* O_RDWR只读打开, O_NDELAY非阻塞方式 */
/*
        fd1 = open(hello_node0, O_RDWR|O_NDELAY);
        if(fd1 < 0) {
                printf("APP open %s failed\n", hello_node0);
                exit(EXIT_FAILURE);
        } else {
                printf("APP open %s success\n", hello_node0);
                ioctl(fd1, 1, 6);
        }
*/
        close(fd0);
        close(fd1);
}

invoke_cahr_driver.c

然后是makefile

TARGET_NAME = char_driver_leds
APP_NAME = invoke_char_gpios
obj-m += $(TARGET_NAME).o

KDIR := /home/topeet/chen/kernel-3.0/iTop4412_Kernel_3.0

PWD ?= $(shell pwd)

all:app
        make -C $(KDIR) M=$(PWD) modules

app:$(APP_NAME)
        arm-none-linux-gnueabi-gcc $(APP_NAME).c -o $(APP_NAME) -static

clean:
        rm -rf *.o *.ko *.mod.c *.symvers *.order *.cmd .$(TARGET_NAME)* $(APP_NAME)

Makefile

测试结果：

[root@iTOP-4412]# insmod char_driver_leds.ko                                                               
[  420.107938] numdev_major is 0!
[  420.109549] numdev_minor is 0!
[  420.112677] register req major number is 248
[  420.125765] cdev_add 0 is success!
[  420.137424] cdev_add 1 is success!
[  420.148881] Gpio led 1 init
[  420.150342] gpio_request EXYNOS4_GPL2(0) failed
[  420.154743] GPIO led 2 init
[  420.165167] Hello World enter!
[root@iTOP-4412]# ./invoke_char_gpios 1 0                                                                  
please input cmd [  431.050669] chardevnode open is success!
[  431.054691] chardevnode release is success!cmd is 1,arg is 0
[  431.060238] chardevnode release is success!
and arg
APP open /dev/chardevnode0 success
[root@iTOP-4412]# ./invoke_char_gpios 1 1                                                                  
please input cmd [  435.289936] chardevnode open is success!
[  435.294047] chardevnode release is success!cmd is 1,arg is 1
[  435.299498] chardevnode release is success!
and arg
APP open /dev/chardevnode0 success
[root@iTOP-4412]# ./invoke_char_gpios 0 0                                                                  
please input cmd [  440.595232] chardevnode open is success!
[  440.599237] chardevnode release is success!cmd is 0,arg is 0
and arg
APP open /dev/chardevnode0 success
[  440.609648] chardevnode release is success!
[root@iTOP-4412]# ./invoke_char_gpios 0 1                                                                  
please input cmd [  443.313565] chardevnode open is success!
[  443.317679] chardevnode release is success!cmd is 0,arg is 1
[  443.323129] chardevnode release is success!
and arg
APP open /dev/chardevnode0 success

[root@iTOP-4412]# rmmod char_driver_leds                                                                   
[  468.722834] Hello World exit!

测试结果

 

转载于:https://www.cnblogs.com/ch122633/p/9452383.html