周立功IMX287开发套件之数码管驱动（linux下74HC595多级串联驱动，数码管驱动）

疫情待在家里很无聊，发现吃土的开发板。好久好久没干linux相关开发了，还是在安美数字的时候干的linux网络应用和部分内核开发，现在忘得差不多了，试着捡起来吧。

硬件：如上图短接帽接法

软件：驱动下面直接贴出来（直接同时驱动四个断码比较水），应用层直接write就行

如果要四位显示不同数据需要改驱动和应用层，驱动增加数码管位使能，应用层需要一个单独进程一直跑显示，另一个传数据。我太懒了，就不写了！

#include <linux/cdev.h>
#include <linux/init.h>
#include <linux/module.h>
#include <mach/gpio.h>
#include <asm/io.h>
#include "mach/../../mx28_pins.h"
#include <mach/pinctrl.h>
#include "mach/mx28.h"
#include <linux/fs.h>
#include <linux/io.h>
#include <asm/uaccess.h>
#include <linux/miscdevice.h>
#include <linux/irq.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/timer.h>

#include <linux/kernel.h>
#include <linux/delay.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <linux/slab.h>
#include <linux/device.h>

#define GPIO_74HC595_DATA_PIN       MXS_PIN_TO_GPIO(PINID_SSP3_MOSI)
#define GPIO_74HC595_STCP_PIN       MXS_PIN_TO_GPIO(PINID_SAIF0_LRCLK)
#define GPIO_74HC595_SHCP_PIN       MXS_PIN_TO_GPIO(PINID_SSP3_SCK)

int nxp74hc595_open(struct inode *, struct file *);
int nxp74hc595_release(struct inode *, struct file *);

ssize_t nxp74hc595_read(struct file *, char *, size_t, loff_t *);
ssize_t nxp74hc595_write(struct file *, const char *, size_t, loff_t *);

int dev_major = 666;
int dev_minor = 0;

char data[2]={0xFF,0x0f};//data[1]选择段码位 data[0]段码内容

static struct class *firstdrv_class;
static struct device *firstdrv_class_dev;
struct cdev *nxp74hc595_cdev;

//将文件操作与分配的设备号相连
struct file_operations nxp74hc595_fops =
{
   owner   : THIS_MODULE,
   open   : nxp74hc595_open,
   release   : nxp74hc595_release,
   write   : nxp74hc595_write,
};

//初始化io引脚
static int __init gpio_74hc595_drv_init(void)
{

int iRet;

   gpio_free(GPIO_74HC595_DATA_PIN);
   gpio_free(GPIO_74HC595_STCP_PIN);
   gpio_free(GPIO_74HC595_SHCP_PIN);

   iRet = gpio_request(GPIO_74HC595_DATA_PIN, "74HC595_DATA");
   if (iRet != 0) {
       printk("request 74HC595_DATA failed \n");
       return -EBUSY;
   }

   iRet = gpio_request(GPIO_74HC595_SHCP_PIN, "74HC595_SHCP");
   if (iRet != 0) {
       printk("request 74HC595_SHCP failed \n");
       return -EBUSY;
   }

   iRet = gpio_request(GPIO_74HC595_STCP_PIN, "74HC595_STCP");
   if (iRet != 0) {
       printk("request 74HC595_STCP failed \n");
       return -EBUSY;
   }

   gpio_direction_output(GPIO_74HC595_DATA_PIN,0);
   gpio_direction_output(GPIO_74HC595_STCP_PIN,0);
   gpio_direction_output(GPIO_74HC595_SHCP_PIN,0);

printk("init all 74HC595 ctl gpio succ \n");
return 0;

}

//向74HC595写入数据
void Write_74HC595(unsigned char ChipNum,unsigned char *DataBuf)
{
unsigned char i = 0;
unsigned char DataBufTmp = 0;

   gpio_set_value(GPIO_74HC595_STCP_PIN,0);//STCP
for(; ChipNum>0; ChipNum--){
DataBufTmp = *DataBuf;
for(i=0; i<8; i++){
           gpio_set_value(GPIO_74HC595_SHCP_PIN,0);//SHCP
if (DataBufTmp & 0x80){
               gpio_set_value(GPIO_74HC595_DATA_PIN,1);
}else{
               gpio_set_value(GPIO_74HC595_DATA_PIN,0);
}
udelay(5);
           gpio_set_value(GPIO_74HC595_SHCP_PIN,1);
udelay(5);
DataBufTmp = DataBufTmp << 1;
}
DataBuf++;
}

gpio_set_value(GPIO_74HC595_STCP_PIN,1);
udelay(10);
gpio_set_value(GPIO_74HC595_STCP_PIN,0);
}

static void __exit nxp74hc595_exit(void)
{

char data[2]={0xFF,0x0f};

   dev_t devno = MKDEV(dev_major, dev_minor);
   cdev_del(nxp74hc595_cdev);
   kfree(nxp74hc595_cdev);

   unregister_chrdev_region(devno, 1);
   device_unregister(firstdrv_class_dev);
   class_destroy(firstdrv_class);

   Write_74HC595(2,data);
   gpio_free(GPIO_74HC595_DATA_PIN);
   gpio_free(GPIO_74HC595_STCP_PIN);
   gpio_free(GPIO_74HC595_SHCP_PIN);
   printk("NXP74hc595 unregister success\n");

}

static int __init nxp74hc595_init(void)
{

int ret, err;
dev_t devno;

ret=alloc_chrdev_region(&devno, dev_minor, 2, "NXP74hc595");
dev_major=MAJOR(devno);

   if(ret<0){
   printk("my74hc595 register failure\n");
       return ret;
   }else{
       printk("74hc595 register success\n");
   }

nxp74hc595_cdev = kmalloc(sizeof(struct cdev), GFP_KERNEL);

cdev_init(nxp74hc595_cdev, &nxp74hc595_fops);

nxp74hc595_cdev->owner = THIS_MODULE;
err = cdev_add(nxp74hc595_cdev, devno, 1);

   if(err<0){
       printk("add device failure\n");
   }

firstdrv_class = class_create(THIS_MODULE, "74HC595");
firstdrv_class_dev = device_create(firstdrv_class, NULL, MKDEV(dev_major, 0), NULL,"NXP74HC595-%d", 1);

gpio_74hc595_drv_init();
Write_74HC595(2,data);

printk("register 74HC595 dev OK\n");
return 0;
}

int nxp74hc595_open(struct inode *inode, struct file *filp)
{
printk("open my74hc595 dev OK\n");
return 0;
}

int nxp74hc595_release(struct inode *inode, struct file *filp)
{
   Write_74HC595(2,data);
   gpio_free(GPIO_74HC595_DATA_PIN);
   gpio_free(GPIO_74HC595_STCP_PIN);
   gpio_free(GPIO_74HC595_SHCP_PIN);
   printk("close NXP74HC595 dev OK\n");
   return 0;
}

ssize_t nxp74hc595_write(struct file *filp, const char *buf, size_t len, loff_t *off)
{
char dataa[2] = {0};

   if(copy_from_user(dataa, buf, 2)){
       return -EFAULT;
   }
   printk("dataa[0] = %d , dataa[1] = %d\n",dataa[0],dataa[1]);

   switch(dataa[0]){
       case 1:data[0] = ~0x06;break;
       case 2:data[0] = ~0x5b;break;
       case 3:data[0] = ~0x4f;break;
       case 4:data[0] = ~0x66;break;
       case 5:data[0] = ~0x6d;break;
       case 6:data[0] = ~0x7d;break;
       case 7:data[0] = ~0x07;break;
       case 8:data[0] = ~0x7f;break;
       case 9:data[0] = ~0x6f;break;
   }

   printk("data[0] = %d \n",data[0]);
   Write_74HC595(2,data);

printk("write nxp74hc595 dev OK\n");
return sizeof(int);
}

MODULE_LICENSE("GPL");
module_init(nxp74hc595_init);
module_exit(nxp74hc595_exit);

来源：CSDN

作者：RamboAimmy

链接：https://blog.csdn.net/weixin_37705509/article/details/104233372

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