gpio模拟pwm信号（风扇转速控制）

一、需求： 　

　四路风扇分别通过PA6\PG9\PG11\PG12四个脚输出pwm信号，控制风扇风速。但是芯片这4个脚没用硬件PWM功能，所以必须使用io口模拟pwm时序。 主要通过高精度定时器hrtimer去模拟pwm时序

二、功能实现

1、dts文件注册pwm设备

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gpio-pwms {         compatible = "gpio-pwms";         pinctrl-names = "default";         pwm1 {             label = "pwm1";             gpios = <&pio 0 6 GPIO_ACTIVE_HIGH>;      //GPIO6 ---> PA6         };            pwm2 {             label = "pwm2";             gpios = <&pio 6 9 GPIO_ACTIVE_HIGH>;      //GPIO201 ---->PG9         };                   pwm3{             label = "pwm3";             gpios = <&pio 6 11 GPIO_ACTIVE_HIGH>; //GPIO203  ----->PG11         };                    pwm4{             label = "pwm4";             gpios = <&pio 6 12 GPIO_ACTIVE_HIGH>; //GPIO204  ----->PG12         };      };

2、驱动编写

(1）解析dts文件中的数据

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static struct gpio_pwms_platform_data * gpio_pwms_get_devtree_pdata(struct device *dev) {     struct device_node *node, *pp;     struct gpio_pwms_platform_data *pdata;     struct pwm_chip *pwm;     int error;     int npwms;     int i = 0;       node = dev->of_node;     if (!node)         return NULL;       npwms = of_get_child_count(node);     //获取dts文件中pwm结点的个数     if (npwms == 0)         return NULL;          pdata = devm_kzalloc(dev, sizeof(*pdata) + npwms * (sizeof *pwm),GFP_KERNEL);     if (!pdata) {         error = -ENOMEM;         goto err_out;     }       pdata->pwms = (struct pwm_chip *)(pdata + 1);     pdata->npwms = npwms;         for_each_child_of_node(node, pp)     {         enum of_gpio_flags flags;           if (!of_find_property(pp, "gpios", NULL))         {             pdata->npwms--;             printk( "Found pwm without gpios\n");             continue;         }           pwm = &pdata->pwms[i++];         pwm->gpio = of_get_gpio_flags(pp, 0, &flags);       //获取每个pwm的gpio         printk("pwm->gpio=%d,flags=%d",pwm->gpio,flags);         if (pwm->gpio < 0)         {             error = pwm->gpio;             if (error != -ENOENT)             {                 if (error != -EPROBE_DEFER)                     dev_err(dev,                         "Failed to get gpio flags, error: %d\n",                         error);                 return ERR_PTR(error);             }         }         else         {             pwm->active_low = flags ;         }             pwm->desc = of_get_property(pp, "label", NULL);   //获取label的字串     }             if (pdata->npwms == 0) {         error = -EINVAL;         goto err_out;     }     return pdata;       err_out:         return ERR_PTR(error);       }

（2）gpio_demo_probe函数主要用于创建pwm设备和class，分别给四个pwm设备分配主设备和次设备号,并且设置io口的输入输出。

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static int gpio_demo_probe(struct platform_device *pdev) {               struct device *dev = &pdev->dev;     int error;     int i,ret=0;     unsigned int gpio;      struct pwm_chip *gpwm = NULL;        pdata = pdev->dev.platform_data;       if (!pdata) {         pdata = gpio_pwms_get_devtree_pdata(dev);    //获取dts中定义设备树的数据         if (IS_ERR(pdata))             return PTR_ERR(pdata);         if (!pdata) {             printk( "missing platform data\n");             return -EINVAL;         }     }       gloabl_pwms_dev = devm_kzalloc(dev, pdata->npwms * sizeof(struct pwm_chip),                GFP_KERNEL);     if (!gloabl_pwms_dev) {         printk("no memory for gloabl_pwms_dev data\n");         return -ENOMEM;     }     memcpy(gloabl_pwms_dev, pdata->pwms, pdata->npwms * sizeof(struct pwm_chip));         for(i=0;i<pdata->npwms;i++)     {　　　　　　　　　　//申请主设备和此设备号,分配了cdev结构，注册了驱动的操作方法集         gpwm = &gloabl_pwms_dev[i];         gpwm->devno = MKDEV(pmajor, i);         register_chrdev_region(gpwm->devno , 1, gpwm->desc);         gpwm->cdev = cdev_alloc();         gpwm->cdev->owner = THIS_MODULE;         cdev_init(gpwm->cdev,&pwm_fops);         cdev_add(gpwm->cdev,gpwm->devno,1);     }             pwm_class = class_create(THIS_MODULE,PWM_CLASS_NAME);   //创建class  gpio-pwm       if(IS_ERR(pwm_class)){         printk("debug:error class_create\n");         ret = PTR_ERR(pwm_class);         goto err_class_error;     }             for (i = 0; i < pdata->npwms; i++)     {         gpwm = &gloabl_pwms_dev[i];          gpio = gpwm->gpio;                   gpwm->dev = device_create(pwm_class,NULL,gpwm->devno,NULL,"pwm%d",i+1);   //创建pwm设备         if(IS_ERR(gpwm->dev)){             printk("debug:error device_create\n");             ret = PTR_ERR(gpwm);             goto err_class_error;         }        else        {           printk("pwm_device_create\n");        }                             if(!gpio_is_valid(gpio))             printk("debug:invalid gpio,gpio=0x%x\n", gpio);            error = gpio_direction_output(gpio, !((gpwm->active_low == OF_GPIO_ACTIVE_LOW) ? 0 : 1));  //设置io口为输出即默认电平         if (error) {             printk(                 "unable to set direction on gpio %u, err=%d\n",                 gpio, error);             return error;         }              //设置默认pwm周期和高电平时间         gpwm->period = 40000;           gpwm->duty = 20000;                  //申请device         error = devm_gpio_request(dev, gpio,gpwm->desc);         if (error) {             printk( "unable to request gpio %u, err=%d\n",                 gpio, error);               goto err_device_create;           }         else         {             printk("successed to request gpio\n");             gpwm->status = PWM_DISABLE;         }               }                return 0;      err_device_create:     device_destroy(pwm_class,gpwm->devno);    err_class_error:     class_destroy(pwm_class);        return ret; }

注册了字符设备后，/dev/目录下会生成pwm1\pwm2\pwm3\pwm4四个字符设备。可以在应用层去对设备进行读写操作，会调用到驱动下的这几个函数。

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const struct file_operations pwm_fops = {     .open = pwm_drv_open,     .write = pwm_drv_write,     .read = pwm_drv_read,     .unlocked_ioctl = pwm_drv_ioctl,     .release = pwm_drv_close, };

（3）pwm_drv_ioctl函数会对应用层发过来的指令进行响应.

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//command#define PWM_PERIOD_SET _IOW('A', 1, unsigned long) #define PWM_DUTY_SET _IOW('A', 2, unsigned long) #define PWM_START _IOW('A', 3, unsigned long)

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long pwm_drv_ioctl(struct file *filep, unsigned int cmd, unsigned long arg) {     int ret = 0,minornum=0;    struct inode * ginode = NULL;   struct pwm_chip * pwm_dev = NULL;    ginode = file_inode(filep);     minornum= iminor(ginode); pwm_dev = &gloabl_pwms_dev[minornum];          printk("pwm_drv_ioctl.minornum=%d...gpio=%d.period=%ld..duty=%ld..\n",minornum,pwm_dev->gpio,pwm_dev->period,pwm_dev->duty);       switch(minornum)     {         case 0:             pwm1_dev =  &gloabl_pwms_dev[minornum];             break;         case 1:             pwm2_dev =  &gloabl_pwms_dev[minornum];             break;         case 2:             pwm3_dev =  &gloabl_pwms_dev[minornum];             break;         case 3:             pwm4_dev =  &gloabl_pwms_dev[minornum];             break;         default:             break;      }          switch(cmd)     {         case PWM_PERIOD_SET :         if(0 == minornum)           {                     pwm1_dev->period = arg;         }         else if(1 == minornum)         {              pwm2_dev->period = arg;         }         else if(2 == minornum)         {              pwm3_dev->period = arg;         }         else if(3 == minornum)         {              pwm4_dev->period = arg;         }                           break;            case PWM_DUTY_SET :         if(0 == minornum)           {                pwm1_dev->duty = arg;         }         else if(1 == minornum)         {             pwm2_dev->duty = arg;         }         else if(2 == minornum)         {             pwm3_dev->duty = arg;         }         else if(3 == minornum)         {             pwm4_dev->duty = arg;         }             break;            case PWM_START :     if(0 == minornum)       {                       if(pwm1_dev->status == PWM_DISABLE){                 // start timer                 pwm_gpio_start(minornum);                 pwm1_dev->status = PWM_ENABLE;                             }else{                 printk("debug:pwm1_gpio aready work\n");             }     }     else if(1 == minornum)     {         if(pwm2_dev->status == PWM_DISABLE){                 // start timer                 pwm_gpio_start(minornum);                 pwm2_dev->status = PWM_ENABLE;                             }else{                 printk("debug:pwm2_gpio aready work\n");             }     }     else if(2 == minornum)     {         if(pwm3_dev->status == PWM_DISABLE){                 // start timer                 pwm_gpio_start(minornum);                 pwm3_dev->status = PWM_ENABLE;                             }else{                 printk("debug:pwm3_gpio aready work\n");             }     }     else if(3 == minornum)     {         if(pwm4_dev->status == PWM_DISABLE){                 // start timer                 pwm_gpio_start(minornum);                 pwm4_dev->status = PWM_ENABLE;                             }else{                 printk("debug:pwm4_gpio aready work\n");             }     }                       break;            default :             ret = -1;             break;     }     return 0;     }

(4)hrtimer精准定时器模拟pwm信号

• 初始化定时器，是指hrtimer1_handler为回调函数，hrtimer_start激活回调函数。　　

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hrtimer_init(&pwm1_dev->mytimer,CLOCK_MONOTONIC,HRTIMER_MODE_REL); pwm1_dev->mytimer.function = hrtimer1_handler; pwm1_dev->kt = ktime_set(0, pwm1_dev->period-pwm1_dev->duty); hrtimer_start(&pwm1_dev->mytimer,pwm1_dev->kt,HRTIMER_MODE_REL);

• 初始化完之后会调用hrtimer1_handler函数，在回调函数会判断io口的电平高低，然后使用ktime_set设置到期时间，如果io为低电平，如果duty不为0，则拉高，ktime_set设置高电平的时间为duty,hrtimer_forward_now函数会等待duty纳秒，然后再执行回调函数hrtimer1_handler，再进行判断，如此循环。使用hrtimer_cancel函数去取消hrtimer.

我们需要四个定时器去模拟pwm,故要写四个回调函数模拟。

注意：根据实际测量，这里gpio_get_value获取到gpio的值，1为低电平，0为高电平。

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static enum hrtimer_restart    hrtimer1_handler(struct hrtimer *timer) {        if (gpio_get_value(pwm1_dev->gpio) == 1) {     // There is no need to pull down when the duty cycle is 100%      if (pwm1_dev->duty != 0) {                     gpio_set_value(pwm1_dev->gpio, 0);         pwm1_dev->kt = ktime_set(0, pwm1_dev->duty);                       }     // timer overflow         hrtimer_forward_now(&pwm1_dev->mytimer, pwm1_dev->kt);     } else {     // There is no need to pull up when the duty cycle is 0                  if (pwm1_dev->duty != pwm1_dev->period) {             gpio_set_value(pwm1_dev->gpio, 1);         pwm1_dev->kt = ktime_set(0, pwm1_dev->period-pwm1_dev->duty);                     }     // timer overflow         hrtimer_forward_now(&pwm1_dev->mytimer, pwm1_dev->kt);     }        return HRTIMER_RESTART;    }

（5）设备注册

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static struct of_device_id gpio_demo_of_match[] = {     {.compatible = "gpio-pwms"},     {}, }    MODULE_DEVICE_TABLE(of, gpio_demo_of_match);    static struct platform_driver gpio_demo_driver = {     .probe = gpio_demo_probe,     .driver = {     .name = "gpio-pwms",     .owner = THIS_MODULE,     .of_match_table = of_match_ptr(gpio_demo_of_match),     } };    static int __init gpio_demo_init(void) {       return platform_driver_register(&gpio_demo_driver); }    static void __exit gpio_demo_exit(void) {     int i;      struct pwm_chip *gpwm = NULL;     for(i=0;i<pdata->npwms;i++ )     {           gpwm = &gloabl_pwms_dev[i];         gpio_set_value(gpwm->gpio, 1);         gpio_free(gpwm->gpio);         device_destroy(pwm_class,gpwm->devno);         cdev_del(gpwm->cdev);         unregister_chrdev_region(gpwm->devno,1);         hrtimer_cancel(&gpwm->mytimer);         kfree(gpwm);     }     class_destroy(pwm_class);           return platform_driver_unregister(&gpio_demo_driver); }    late_initcall(gpio_demo_init); module_exit(gpio_demo_exit); // add by SouthLj 2019-0924 end    MODULE_LICENSE("GPL"); MODULE_AUTHOR("SouthLj");

（6）注册成功 

注册完pwm设备和gpio_pwms class就可以看到如下目录：

可以看到设备的主、次设备号：

/dev目录下也可以看到四个设备，应用层就会通过ioctl对pwm设备写数据到驱动。

三、调用控制

　

 

 

　　luci界面中设置风扇的数据后，会将数据更新到/etc/config/cgminer配置文件中，然后重新启动cgminer(即执行/etc/init.d/cgminer脚本)，脚本中会将风扇风速最大最小值、风速默认值、风速自动控制、预启动时间以及预启动时间内风扇的风速，通过传参传给cgminer.

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AVA9_OPTIONS=" --fan-limit $_fan_min-$_fan_max $VOLT_OFFSET"     PARAMS=" --lowmem $AVA9_OPTIONS $POOL1 $POOL2 $POOL3 --api-allow $_aa --api-listen $_mo --fan-ctrl $_fan_ctrl $PRE_BOOT --pwm-default $_pwm_default"     NTP_POOL="-p 0.openwrt.pool.ntp.org -p 1.openwrt.pool.ntp.org  -p 3.openwrt.pool.ntp.org -p 4.openwrt.pool.ntp.org"     ASIA="-p 1.cn.pool.ntp.org -p 3.asia.pool.ntp.org -p 2.asia.pool.ntp.org"       # _ntp_enable: openwrt, asia, globle     if [ "$_ntp_enable" == "asia" ]; then         NTP_POOL="${ASIA}"     fi       if [ ! -f /tmp/cgminer-ntpd-done -a "$_ntp_enable" != "disable" ]; then         while [ "$NTPD_RET" != "0" ]; do         ntpd -d -n -q -N ${NTP_POOL}         NTPD_RET=$?         done           touch /tmp/cgminer-ntpd-done     fi           # Make sure udevd run before cgminer start         UDEVDCNT=`pidof udevd | wc -w`         if [ "$UDEVDCNT" == "0" ]; then                 mkdir -p /run                 udevd --daemon         fi       sleep 2     start-stop-daemon -S -x $APP -p $PID_FILE -m -b -- $PARAMS

pwm占空比设到20%，pwm波形不稳定,导致风扇有顿挫感。nano给的软件默认最小占空比为30%.

cgminer.c中通过参数判断会执行相应的函数：

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char *set_avalon9_fan_auto_control(char *arg) {     int ret=1,autocontrol=0;     ret = sscanf(arg, "%d", &autocontrol);     printf("autocontrol=%d\n",autocontrol);     if (ret < 1)         return "No value passed to avalon9-fan-auto-control";       opt_avalon9_fan_auto_control = autocontrol;                   return NULL; }

1	//风扇预启动设置逻辑是，如果风扇自动控制开关为enable,控制板上电开机后，则会根据预启动速度跑，跑的时间是预启动时间，时间过后，风扇风速会按照默认风速转。预启动设置只在上电第一次有效。

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char *set_avalon9_fan_pre_boot_setup(char *arg) {     int ret=1,prebootime =1,prebootfan =100;     ret = sscanf(arg, "%d-%d", &prebootfan,&prebootime);     printf("prebootime=%d,prebootfan=%d\n",prebootime,prebootfan);     if (prebootfan < 0 || prebootfan> 100 || prebootime < 0 || prebootime > 10)         return "Invalid value passed to boot_setup";     if (ret < 1)         return "No value passed to avalon9-fan-pre-boot-setup";     prebootflag = 1;     opt_avalon9_fan_pre_boottim = prebootime;     opt_avalon9_fan_pre_bootfan = prebootfan;     return NULL;       }   void open_pwm_device(float pwmval) {     int fd;     fd = open("/dev/pwm1",O_RDWR );         if(fd < 0)      {                  printf("failed to open pwm1 failed!\n");             }              ioctl(fd,PWM_PERIOD_SET,40000);   // 10 000 00ns = 1ms     10 00ns = 1us         ioctl(fd,PWM_DUTY_SET,(int)(40000*((float)pwmval/100)));       ioctl(fd,PWM_START,1);        close(fd);                           fd = open("/dev/pwm2",O_RDWR);              if(fd < 0)      {               printf("failed to open pwm2!\n");             }         ioctl(fd,PWM_PERIOD_SET,40000);   // 10 000 000ns = 10ms         ioctl(fd,PWM_DUTY_SET,(int)(40000*((float)pwmval/100)));        ioctl(fd,PWM_START,1);         close(fd);               fd = open("/dev/pwm3",O_RDWR);       if(fd < 0)     {           printf("failed to open pwm3 failed!\n");             }        ioctl(fd,PWM_PERIOD_SET,40000);   // 10 000 000ns = 10ms       ioctl(fd,PWM_DUTY_SET,(int)(40000*((float)pwmval/100)));       ioctl(fd,PWM_START,1);      close(fd);                fd = open("/dev/pwm4",O_RDWR);      if(fd < 0)     {               printf("failed to open pwm4! \n");        }          ioctl(fd,PWM_PERIOD_SET,40000);   // 10 000 000ns = 10ms        ioctl(fd,PWM_DUTY_SET,(int)(40000*((float)pwmval/100)));       ioctl(fd,PWM_START,1);       close(fd);         }   char *set_avalon9_fan_pwm_default(char *arg) {           int pwmval;       int ret=1; //  int  delaytime  =  90000000;     ret = sscanf(arg, "%d", &pwmval);     printf("\n...........set_avalon9_fan_default_pwm....pwmval=%d..opt_avalon9_fan_auto_control=%d...\n",pwmval,opt_avalon9_fan_auto_control);     if (ret < 1)         return "No value passed to avalon9-fan-default-pwm";                 if(pwmval<opt_avalon9_fan_min)         {           pwmval =opt_avalon9_fan_min;         }     else if(pwmval>opt_avalon9_fan_max)      {         pwmval =opt_avalon9_fan_max;      }       if(opt_avalon9_fan_auto_control == 1)     {                      if(opt_avalon9_fan_pre_bootfan<opt_avalon9_fan_min)             {               opt_avalon9_fan_pre_bootfan =opt_avalon9_fan_min;             }         else if(opt_avalon9_fan_pre_bootfan>opt_avalon9_fan_max)          {             opt_avalon9_fan_pre_bootfan =opt_avalon9_fan_max;          }         if(prebootflag==1)         {               prebootflag==0;             open_pwm_device(opt_avalon9_fan_pre_bootfan);             cgsleep_ms(opt_avalon9_fan_pre_boottim*60000);         }         open_pwm_device(pwmval);     }     else     {         open_pwm_device(pwmval);     }           return NULL; }

　通过cat /sys/class/kernel/gpio命令查看四个pwm口的电平高低。

四、源码：

dts文件：

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gpio-pwms {     compatible = "gpio-pwms";     pinctrl-names = "default";     pwm1 {         label = "pwm1";         gpios = <&pio 0 6 GPIO_ACTIVE_HIGH>;     };       pwm2 {         label = "pwm2";         gpios = <&pio 6 9 GPIO_ACTIVE_HIGH>;     };           pwm3{         label = "pwm3";         gpios = <&pio 6 11 GPIO_ACTIVE_HIGH>;     };            pwm4{         label = "pwm4";         gpios = <&pio 6 12 GPIO_ACTIVE_HIGH>;     };  };

pwm_gpio.h:

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/**  * pwm_gpio.h create by yuan */    #ifndef __PWM_GPIO_H__ #define __PWM_GPIO_H__    #include <linux/ioctl.h>    #define PWM_PERIOD_SET _IOW('A', 1, unsigned long) #define PWM_DUTY_SET _IOW('A', 2, unsigned long) #define PWM_START _IOW('A', 3, unsigned long)      #endif /* pwm-gpio.h */

pwm_gpio.c:

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/**  * pwm_gpio.c create by yuanqiangfei */    #include <linux/init.h> #include <linux/module.h> #include <linux/fs.h> #include <linux/device.h> #include <linux/slab.h> #include <linux/cdev.h> #include <linux/interrupt.h> #include <linux/gpio.h> #include <linux/input.h> #include <linux/sched.h> #include <linux/wait.h> #include <linux/delay.h>     #include <linux/kernel.h> #include <linux/uaccess.h> #include <linux/io.h>    #include <linux/platform_device.h> #include <linux/of_platform.h> #include <linux/of_gpio.h> #include <linux/of_device.h>    #include <linux/pwm-gpio.h>      #define PWM_CLASS_NAME   "gpio-pwms"    //产生sys/class/gpio-pwms #define PWM_DEVICE_NUM     0         //产生/dev/pwm-0    typedef enum {     PWM_DISABLE = 0,     PWM_ENABLE, }PWM_STATUS_t;    //pwm的设备对象 struct pwm_chip{     dev_t devno;                    struct cdev *cdev;     struct device *dev;     unsigned long period;     unsigned long duty;     struct hrtimer mytimer;     ktime_t kt;     PWM_STATUS_t status;     char *desc;    int gpio;    int active_low;      };   struct gpio_pwms_platform_data {      struct pwm_chip  *pwms;     int npwms; };    static int pmajor = 247; struct pwm_chip *pwm1_dev = NULL; struct pwm_chip *pwm2_dev = NULL; struct pwm_chip *pwm3_dev = NULL; struct pwm_chip *pwm4_dev = NULL; static struct class *pwm_class = NULL; static struct pwm_chip *gloabl_pwms_dev = NULL; static struct gpio_pwms_platform_data *pdata = NULL; static void pwm_gpio_start(int minor); static enum hrtimer_restart    hrtimer1_handler(struct hrtimer *timer); static enum hrtimer_restart    hrtimer2_handler(struct hrtimer *timer); static enum hrtimer_restart    hrtimer3_handler(struct hrtimer *timer); static enum hrtimer_restart    hrtimer4_handler(struct hrtimer *timer);    int pwm_drv_open (struct inode * inode, struct file *filp) {     return 0; }    ssize_t pwm_drv_read (struct file *filp, char __user *userbuf, size_t count, loff_t *fpos) {     return 0; } ssize_t pwm_drv_write (struct file *filp, const char __user *userbuf, size_t count, loff_t *fpos) {     return 0; }    long pwm_drv_ioctl(struct file *filep, unsigned int cmd, unsigned long arg) {     int ret = 0,minornum=0;    struct inode * ginode = NULL;   struct pwm_chip * pwm_dev = NULL;    ginode = file_inode(filep);     minornum= iminor(ginode); pwm_dev = &gloabl_pwms_dev[minornum];          printk("pwm_drv_ioctl.minornum=%d...gpio=%d.period=%ld..duty=%ld..\n",minornum,pwm_dev->gpio,pwm_dev->period,pwm_dev->duty);       switch(minornum)     {         case 0:             pwm1_dev =  &gloabl_pwms_dev[minornum];             break;         case 1:             pwm2_dev =  &gloabl_pwms_dev[minornum];             break;         case 2:             pwm3_dev =  &gloabl_pwms_dev[minornum];             break;         case 3:             pwm4_dev =  &gloabl_pwms_dev[minornum];             break;         default:             break;      }          switch(cmd)     {         case PWM_PERIOD_SET :         if(0 == minornum)           {                     pwm1_dev->period = arg;         }         else if(1 == minornum)         {              pwm2_dev->period = arg;         }         else if(2 == minornum)         {              pwm3_dev->period = arg;         }         else if(3 == minornum)         {              pwm4_dev->period = arg;         }                           break;            case PWM_DUTY_SET :         if(0 == minornum)           {                pwm1_dev->duty = arg;         }         else if(1 == minornum)         {             pwm2_dev->duty = arg;         }         else if(2 == minornum)         {             pwm3_dev->duty = arg;         }         else if(3 == minornum)         {             pwm4_dev->duty = arg;         }             break;            case PWM_START :     if(0 == minornum)       {                       if(pwm1_dev->status == PWM_DISABLE){                 // start timer                 pwm_gpio_start(minornum);                 pwm1_dev->status = PWM_ENABLE;                             }else{                 printk("debug:pwm1_gpio aready work\n");             }     }     else if(1 == minornum)     {         if(pwm2_dev->status == PWM_DISABLE){                 // start timer                 pwm_gpio_start(minornum);                 pwm2_dev->status = PWM_ENABLE;                             }else{                 printk("debug:pwm2_gpio aready work\n");             }     }     else if(2 == minornum)     {         if(pwm3_dev->status == PWM_DISABLE){                 // start timer                 pwm_gpio_start(minornum);                 pwm3_dev->status = PWM_ENABLE;                             }else{                 printk("debug:pwm3_gpio aready work\n");             }     }     else if(3 == minornum)     {         if(pwm4_dev->status == PWM_DISABLE){                 // start timer                 pwm_gpio_start(minornum);                 pwm4_dev->status = PWM_ENABLE;                             }else{                 printk("debug:pwm4_gpio aready work\n");             }     }                       break;            default :             ret = -1;             break;     }     return 0;     }    int pwm_drv_close (struct inode *inode, struct file *filp) {   printk("pwm_drv_close...\n");     return 0; }       static void pwm_gpio_start(int minor) {        printk("pwm_gpio_start...minor=%d..\n",minor);     switch(minor)     {         case 0:              hrtimer_init(&pwm1_dev->mytimer,CLOCK_MONOTONIC,HRTIMER_MODE_REL);              pwm1_dev->mytimer.function = hrtimer1_handler;              pwm1_dev->kt = ktime_set(0, pwm1_dev->period-pwm1_dev->duty);                  hrtimer_start(&pwm1_dev->mytimer,pwm1_dev->kt,HRTIMER_MODE_REL);             break;           case 1:              hrtimer_init(&pwm2_dev->mytimer,CLOCK_MONOTONIC,HRTIMER_MODE_REL);              pwm2_dev->mytimer.function = hrtimer2_handler;              pwm2_dev->kt = ktime_set(0, pwm2_dev->period-pwm2_dev->duty);              hrtimer_start(&pwm2_dev->mytimer,pwm2_dev->kt,HRTIMER_MODE_REL);             break;           case 2:              hrtimer_init(&pwm3_dev->mytimer,CLOCK_MONOTONIC,HRTIMER_MODE_REL);              pwm3_dev->mytimer.function = hrtimer3_handler;              pwm3_dev->kt = ktime_set(0,pwm3_dev->period -pwm3_dev->duty);              hrtimer_start(&pwm3_dev->mytimer,pwm3_dev->kt,HRTIMER_MODE_REL);             break;           case 3:              hrtimer_init(&pwm4_dev->mytimer,CLOCK_MONOTONIC,HRTIMER_MODE_REL);              pwm4_dev->mytimer.function = hrtimer4_handler;              pwm4_dev->kt = ktime_set(0, pwm4_dev->period-pwm4_dev->duty);              hrtimer_start(&pwm4_dev->mytimer,pwm4_dev->kt,HRTIMER_MODE_REL);             break;          default:             break;      }   }    static enum hrtimer_restart    hrtimer1_handler(struct hrtimer *timer) {        if (gpio_get_value(pwm1_dev->gpio) == 1) {     // There is no need to pull down when the duty cycle is 100%      if (pwm1_dev->duty != 0) {                     gpio_set_value(pwm1_dev->gpio, 0);         pwm1_dev->kt = ktime_set(0, pwm1_dev->duty);                       }     // timer overflow         hrtimer_forward_now(&pwm1_dev->mytimer, pwm1_dev->kt);     } else {     // There is no need to pull up when the duty cycle is 0                  if (pwm1_dev->duty != pwm1_dev->period) {             gpio_set_value(pwm1_dev->gpio, 1);         pwm1_dev->kt = ktime_set(0, pwm1_dev->period-pwm1_dev->duty);                     }     // timer overflow         hrtimer_forward_now(&pwm1_dev->mytimer, pwm1_dev->kt);     }        return HRTIMER_RESTART;    }   static enum hrtimer_restart    hrtimer2_handler(struct hrtimer *timer) {        if (gpio_get_value(pwm2_dev->gpio) == 1) {     // There is no need to pull down when the duty cycle is 100%      if (pwm2_dev->duty != 0) {               gpio_set_value(pwm2_dev->gpio, 0);              pwm2_dev->kt = ktime_set(0, pwm2_dev->duty);         }     // timer overflow         hrtimer_forward_now(&pwm2_dev->mytimer, pwm2_dev->kt);     } else {     // There is no need to pull up when the duty cycle is 0              if (pwm2_dev->duty != pwm2_dev->period) {              gpio_set_value(pwm2_dev->gpio, 1);         pwm2_dev->kt = ktime_set(0, pwm2_dev->period-pwm2_dev->duty);          }     // timer overflow         hrtimer_forward_now(&pwm2_dev->mytimer, pwm2_dev->kt);     }        return HRTIMER_RESTART;    }   static enum hrtimer_restart    hrtimer3_handler(struct hrtimer *timer) {        if (gpio_get_value(pwm3_dev->gpio) == 1) {     // There is no need to pull down when the duty cycle is 100%           if (pwm3_dev->duty != 0) {             gpio_set_value(pwm3_dev->gpio, 0);             pwm3_dev->kt = ktime_set(0, pwm3_dev->duty);         }     // timer overflow         hrtimer_forward_now(&pwm3_dev->mytimer, pwm3_dev->kt);     } else {     // There is no need to pull up when the duty cycle is 0                   if (pwm3_dev->duty != pwm3_dev->period) {                     gpio_set_value(pwm3_dev->gpio, 1);         pwm3_dev->kt = ktime_set(0, pwm3_dev->period-pwm3_dev->duty);              }     // timer overflow         hrtimer_forward_now(&pwm3_dev->mytimer, pwm3_dev->kt);     }        return HRTIMER_RESTART;    }    static enum hrtimer_restart    hrtimer4_handler(struct hrtimer *timer) {      if (gpio_get_value(pwm4_dev->gpio) == 1) {     // There is no need to pull down when the duty cycle is 100%         if (pwm4_dev->duty != 0) {                 gpio_set_value(pwm4_dev->gpio, 0);        pwm4_dev->kt = ktime_set(0, pwm4_dev->duty);               }     // timer overflow         hrtimer_forward_now(&pwm4_dev->mytimer, pwm4_dev->kt);     } else {     // There is no need to pull up when the duty cycle is 0         if (pwm4_dev->duty != pwm4_dev->period) {                gpio_set_value(pwm4_dev->gpio, 1);              pwm4_dev->kt = ktime_set(0, pwm4_dev->period-pwm4_dev->duty);         }     // timer overflow         hrtimer_forward_now(&pwm4_dev->mytimer, pwm4_dev->kt);     }        return HRTIMER_RESTART;    }       const struct file_operations pwm_fops = {     .open = pwm_drv_open,     .write = pwm_drv_write,     .read = pwm_drv_read,     .unlocked_ioctl = pwm_drv_ioctl,     .release = pwm_drv_close, };    static struct gpio_pwms_platform_data * gpio_pwms_get_devtree_pdata(struct device *dev) {     struct device_node *node, *pp;     struct gpio_pwms_platform_data *pdata;     struct pwm_chip *pwm;     int error;     int npwms;     int i = 0;       node = dev->of_node;     if (!node)         return NULL;       npwms = of_get_child_count(node);     if (npwms == 0)         return NULL;          pdata = devm_kzalloc(dev, sizeof(*pdata) + npwms * (sizeof *pwm),GFP_KERNEL);     if (!pdata) {         error = -ENOMEM;         goto err_out;     }       pdata->pwms = (struct pwm_chip *)(pdata + 1);     pdata->npwms = npwms;         for_each_child_of_node(node, pp)     {         enum of_gpio_flags flags;           if (!of_find_property(pp, "gpios", NULL))         {             pdata->npwms--;             printk( "Found pwm without gpios\n");             continue;         }           pwm = &pdata->pwms[i++];         pwm->gpio = of_get_gpio_flags(pp, 0, &flags);         printk("pwm->gpio=%d,flags=%d",pwm->gpio,flags);         if (pwm->gpio < 0)         {             error = pwm->gpio;             if (error != -ENOENT)             {                 if (error != -EPROBE_DEFER)                     dev_err(dev,                         "Failed to get gpio flags, error: %d\n",                         error);                 return ERR_PTR(error);             }         }         else         {             pwm->active_low = flags ;         }             pwm->desc = of_get_property(pp, "label", NULL);     }             if (pdata->npwms == 0) {         error = -EINVAL;         goto err_out;     }     return pdata;       err_out:         return ERR_PTR(error);       }    static int gpio_demo_probe(struct platform_device *pdev) {               struct device *dev = &pdev->dev;     int error;     int i,ret=0;     unsigned int gpio;      struct pwm_chip *gpwm = NULL;        pdata = pdev->dev.platform_data;       if (!pdata) {         pdata = gpio_pwms_get_devtree_pdata(dev);         if (IS_ERR(pdata))             return PTR_ERR(pdata);         if (!pdata) {             printk( "missing platform data\n");             return -EINVAL;         }     }       gloabl_pwms_dev = devm_kzalloc(dev, pdata->npwms * sizeof(struct pwm_chip),                GFP_KERNEL);     if (!gloabl_pwms_dev) {         printk("no memory for gloabl_pwms_dev data\n");         return -ENOMEM;     }     memcpy(gloabl_pwms_dev, pdata->pwms, pdata->npwms * sizeof(struct pwm_chip));         for(i=0;i<pdata->npwms;i++)     {         gpwm = &gloabl_pwms_dev[i];         gpwm->devno = MKDEV(pmajor, i);         register_chrdev_region(gpwm->devno , 1, gpwm->desc);         gpwm->cdev = cdev_alloc();         gpwm->cdev->owner = THIS_MODULE;         cdev_init(gpwm->cdev,&pwm_fops);         cdev_add(gpwm->cdev,gpwm->devno,1);     }             pwm_class = class_create(THIS_MODULE,PWM_CLASS_NAME);       if(IS_ERR(pwm_class)){         printk("debug:error class_create\n");         ret = PTR_ERR(pwm_class);         goto err_class_error;     }             for (i = 0; i < pdata->npwms; i++)     {         gpwm = &gloabl_pwms_dev[i];          gpio = gpwm->gpio;                   gpwm->dev = device_create(pwm_class,NULL,gpwm->devno,NULL,"pwm%d",i+1);         if(IS_ERR(gpwm->dev)){             printk("debug:error device_create\n");             ret = PTR_ERR(gpwm);             goto err_class_error;         }        else        {           printk("pwm_device_create\n");        }                             if(!gpio_is_valid(gpio))             printk("debug:invalid gpio,gpio=0x%x\n", gpio);            error = gpio_direction_output(gpio, !((gpwm->active_low == OF_GPIO_ACTIVE_LOW) ? 0 : 1));         if (error) {             printk(                 "unable to set direction on gpio %u, err=%d\n",                 gpio, error);             return error;         }            gpwm->period = 40000;         gpwm->duty = 20000;            error = devm_gpio_request(dev, gpio,gpwm->desc);         if (error) {             printk( "unable to request gpio %u, err=%d\n",                 gpio, error);               goto err_device_create;           }         else         {             printk("successed to request gpio\n");             gpwm->status = PWM_DISABLE;         }               }                return 0;      err_device_create:     device_destroy(pwm_class,gpwm->devno);    err_class_error:     class_destroy(pwm_class);        return ret; }      static struct of_device_id gpio_demo_of_match[] = {     {.compatible = "gpio-pwms"},     {}, }    MODULE_DEVICE_TABLE(of, gpio_demo_of_match);    static struct platform_driver gpio_demo_driver = {     .probe = gpio_demo_probe,     .driver = {     .name = "gpio-pwms",     .owner = THIS_MODULE,     .of_match_table = of_match_ptr(gpio_demo_of_match),     } };    static int __init gpio_demo_init(void) {       return platform_driver_register(&gpio_demo_driver); }    static void __exit gpio_demo_exit(void) {     int i;      struct pwm_chip *gpwm = NULL;     for(i=0;i<pdata->npwms;i++ )     {           gpwm = &gloabl_pwms_dev[i];         gpio_set_value(gpwm->gpio, 1);         gpio_free(gpwm->gpio);         device_destroy(pwm_class,gpwm->devno);         cdev_del(gpwm->cdev);         unregister_chrdev_region(gpwm->devno,1);         hrtimer_cancel(&gpwm->mytimer);         kfree(gpwm);     }     class_destroy(pwm_class);           return platform_driver_unregister(&gpio_demo_driver); }    late_initcall(gpio_demo_init); module_exit(gpio_demo_exit); // add by SouthLj 2019-0924 end    MODULE_LICENSE("GPL"); MODULE_AUTHOR("SouthLj"); /* end pwm_gpio.c */