一、4412 xpwmTOUT1

这是4412的GPD0_1路，itop中被使用为LCD的背光电路的pwm功能。因此如果使用教程中的代码，同样操作GPD0_1是行不通的。

会出现错误，所以需要解除在内核中的占用

修改arch/arm/mach-exynos/mach-itop4412.c，找到并注释

samsung_bl_set(&smdk4x12_bl_gpio_info, &smdk4x12_bl_data);

在内核中取消相关的模块编译，（不确定）

Device Driver>>Graphics support>>Backlight & LCD device support（取消）

然后在平台文件中增加注册设备：

&s3c_device_timer[1],

然后是测试代码：

my_pwm3.c

#include <linux/module.h>

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#define DEVICE_NAME "my_pwm3_dev"

#define DRIVER_NAME "my_pwm3_drv"

#define PWM_MAGIC 'p'

#define PWM_MAX_NR 3

#define PWM_IOCTL_STOP      _IO(PWM_MAGIC, 0)

#define PWM_IOCTL_SET_FREQ  _IO(PWM_MAGIC, 1)

#define PWM_IOCTL_SET_DUTY  _IO(PWM_MAGIC, 2)

#define NS_IN_1HZ                               (1000000000UL)

#define BUZZER_PWM_ID                   0

#define PWM1_ID                                 1

#define PWM2_ID                 2

#define PWM3_ID                 3

#define BUZZER_PMW_GPIO EXYNOS4_GPD0(0)

#define PWM1_GPIO               EXYNOS4_GPD0(1)

#define PWM2_GPIO       EXYNOS4_GPD0(2)

#define PWM3_GPIO       EXYNOS4_GPD0(3)

static struct pwm_device *pwm4buzzer;

static struct semaphore lock;

static int period_ns = 1000;

static unsigned long freq = 50;

static unsigned long duty = 2;

static void pwm_set_freq(void)

{

    //配置周期

    period_ns = NS_IN_1HZ / freq;

    //配置占空比

        if(duty < 1)

                duty = 1;

    pwm_disable(pwm4buzzer);

    pwm_config(pwm4buzzer, period_ns / duty, period_ns);

    pwm_enable(pwm4buzzer);

    //配置相应的GPIO，蜂鸣器IO配置成PWM输出模式

    s3c_gpio_cfgpin(PWM3_GPIO, S3C_GPIO_SFN(2));

}

static void pwm_stop(void)

{

    s3c_gpio_cfgpin(PWM3_GPIO, S3C_GPIO_OUTPUT);

    pwm_config(pwm4buzzer, 0, NS_IN_1HZ / 100);

    pwm_disable(pwm4buzzer);

}

static int ops_pwm_open(struct inode *inode, struct file *file)

{

    if(!down_trylock(&lock))

        return 0;

    else

        return -EBUSY;

}

static int ops_pwm_close(struct inode *inode, struct file *file)

{

    up(&lock);

    return 0;

}

static long ops_pwm_ioctl(struct file *filep, unsigned int cmd,

                unsigned long arg)

{

    if(_IOC_TYPE(cmd)!=PWM_MAGIC) return -EINVAL;

    if(_IOC_NR(cmd) > PWM_MAX_NR) return -EINVAL;

    switch(cmd) {

    case PWM_IOCTL_SET_FREQ:

        if(arg == 0)

            return -EINVAL;

        get_user(freq, (unsigned long __user *)arg);

        printk(KERN_EMERG "freq is %ldn", freq);

        pwm_set_freq();

        break;

    case PWM_IOCTL_STOP:

        pwm_stop();

                break;

        case PWM_IOCTL_SET_DUTY:

        get_user(duty, (unsigned long __user *)arg);

        printk(KERN_EMERG "duty is %ldn", duty);

        pwm_set_freq();

                break;

    default:

        pwm_stop();

        break;

    }

    return 0;

}

static struct file_operations pwm_ops = {

    .owner = THIS_MODULE,

    .open  = ops_pwm_open,

    .release = ops_pwm_close,

    .unlocked_ioctl = ops_pwm_ioctl,

};

static struct miscdevice pwm_misc_dev = {

    .minor = MISC_DYNAMIC_MINOR,

    .name  = DEVICE_NAME,

    .fops  = &pwm_ops,

};

static int __init iTop4412_pwm_dev_init(void)

{

    int ret;

    gpio_free(PWM3_GPIO);

    ret = gpio_request(PWM3_GPIO, DEVICE_NAME);

    if(ret) {

                printk(KERN_EMERG "request GPIO %d for pwm failedn", PWM3_GPIO);

                return ret;

    }

        gpio_set_value(PWM3_GPIO, 0);

        s3c_gpio_cfgpin(PWM3_GPIO, S3C_GPIO_OUTPUT);

        pwm4buzzer = pwm_request(PWM3_ID, DEVICE_NAME);

        if (IS_ERR(pwm4buzzer)) {

                printk(KERN_EMERG "request pwm %d for %s failedn", PWM3_ID, DEVICE_NAME);

                return -ENODEV;

        }

    pwm_stop();

    sema_init(&lock, 1);

    ret = misc_register(&pwm_misc_dev);

        if(ret < 0) {

                gpio_free(BUZZER_PMW_GPIO);

                pwm_free(pwm4buzzer);

                misc_deregister(&pwm_misc_dev);

        }

    printk(KERN_EMERG "tinitializedn");

    return ret;

}

static void __exit iTop4412_pwm_dev_exit(void)

{

    gpio_free(BUZZER_PMW_GPIO);

        pwm_free(pwm4buzzer);

    misc_deregister(&pwm_misc_dev);

    printk(KERN_EMERG "texitn");

    return;

}

module_init(iTop4412_pwm_dev_init);

module_exit(iTop4412_pwm_dev_exit);

MODULE_LICENSE("GPL");

MODULE_AUTHOR("Chen Tuo");

MODULE_DESCRIPTION("Exynos4 PWM Driver");

然后是应用程序：

my_pwm3_app.c

#include

#include

#include

#include

#include

#include

#define PWM2_NAME "/dev/my_pwm3_dev"

#define PWM_MAGIC 'p'

#define PWM_MAX_NR 3

#define PWM_IOCTL_STOP      _IO(PWM_MAGIC, 0)

#define PWM_IOCTL_SET_FREQ  _IO(PWM_MAGIC, 1)

#define PWM_IOCTL_SET_DUTY  _IO(PWM_MAGIC, 2)

int fd = -1;

void open_pwm1(void);

void close_pwm1(void);

void set_pwm_freq(int freq);

void set_pwm_duty(int duty);

void stop_pwm(void);

void open_pwm1(void)

{

    fd = open(PWM2_NAME, O_RDWR);

    if(fd < 0) {

        perror("open pwm1 device");

        exit(1);

    }

//    atexit(close_pwm1);

}

void close_pwm1(void)

{

    if(fd >= 0) {

        ioctl(fd, PWM_IOCTL_STOP);

        close(fd);

        fd = -1;

    }

}

void set_pwm_freq(int freq)

{

    int ret = ioctl(fd, PWM_IOCTL_SET_FREQ, &freq);

    if(ret < 0) {

        perror("set the frequency of the buzzer");

        exit(1);

    }

}

void set_pwm_duty(int duty)

{

    int ret = ioctl(fd, PWM_IOCTL_SET_DUTY, &duty);

    if(ret < 0) {

        perror("set the duty of the pwm");

        exit(1);

    }

}

void stop_pwm(void)

{

    int ret = ioctl(fd, PWM_IOCTL_STOP);

    if(ret < 0) {

        perror("Stop the buzzer");

        exit(1);

    }

}

int main(int argc, char *argv[])

{

    int freq = 1000;

    open_pwm1();

    stop_pwm();

    if(argc < 3) {

        printf("usage:%s [cmd] [arg]n", argv[0]);

        printf("tstop:%s [0] [0] n",argv[0]);

        printf("tset freq:%s [1] [arg]n", argv[0]);

        printf("tset duty:%s [2] [arg]n", argv[0]);

    }

        switch(atoi(argv[1]))

        {

        case 2:

                set_pwm_duty(atoi(argv[2]));

        break;

        case 1:

                set_pwm_freq(atoi(argv[2]));

                break;

    case 0:

        default:

                stop_pwm();

                return -1;

        }

        return 0;

}

最后是Makefile：

Makefile

TARGET_NAME = my_pwm3

#TARGET_NAME = example_pwm

APP1_NAME = my_pwm3_app

#APP2_NAME = open_atomic_int_two

obj-m += $(TARGET_NAME).o

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

PWD ?= $(shell pwd)

all:app1

        make -C $(KDIR) M=$(PWD) modules

app1:

        arm-none-linux-gnueabi-gcc $(APP1_NAME).c -o $(APP1_NAME) -static

#app2:

#       arm-none-linux-gnueabi-gcc $(APP2_NAME).c -o $(APP2_NAME) -static

clean:

        rm -rf *.o *.ko *.mod.c *.symvers *.order

        .$(TARGET_NAME)* $(APP1_NAME) $(APP2_NAME)