用法：
先下发下面的命令让kernel信息打印到串口：
echo 7 4 1 7 > /proc/sys/kernel/printk
然后增加程序可执行性：
chmod 777 pwmdriver_app
先执行 ./pwmdriver_app /dev/pwm 400000 200 然后执行./pwm_driver_app /dev/pwm 400000 200， 可以发现LED[1]明显变暗。
底层硬件设计
module av_pwm(
input clk,
input reset_n,
input as_read,
input as_address,
input as_write,
output reg [31:0] as_readdata,
input [31:0] as_writedata,
output reg led);
reg [31:0]cnt_freq;
reg [31:0]cnt_duty;
reg [31:0] cnt0;
wire end_cnt0;
//写pwm频率寄存器
always@(posedge clk or negedge reset_n)
if(!reset_n) begin
cnt_freq <= 32'd0;
end
else if(as_write && (as_address == 0))begin
cnt_freq <= as_writedata;
end
else begin
cnt_freq <= cnt_freq;
end
//写pwm占空比寄存器
always@(posedge clk or negedge reset_n)
if(!reset_n) begin
cnt_duty <= 32'd0;
end
else if(as_write && (as_address == 1)) begin
cnt_duty <= as_writedata;
end
else begin
cnt_duty <= cnt_duty;
end
//读寄存器
always@(posedge clk or negedge reset_n)
if(!reset_n)
as_readdata <= 32'd0;
else if(as_read)begin
case(as_address)
0:as_readdata <= cnt_freq;
1:as_readdata <= cnt_duty;
default:as_readdata <= 32'd0;
endcase
end
always @(posedge clk or negedge reset_n)begin
if(!reset_n)begin
cnt0 <= 0;
end
else begin
if(end_cnt0)begin
cnt0 <= 0;end
else begin
cnt0 <= cnt0 + 1;
end
end
end
assign end_cnt0 = (cnt0==cnt_freq -1);
always @(posedge clk or negedge reset_n)begin
if(reset_n==1'b0)begin
led <= 1;
end
else if(cnt0==cnt_duty-1)begin
led <= 0;
end
else if(end_cnt0)begin
led <= 1;
end
end
endmodule
底层Linux驱动设计
#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/printk.h>
#include <linux/list.h>
#include <linux/uaccess.h>
//#include <linux/version.h>
//#include <linux/slab.h>
#include <asm/io.h>
#include "hps_0.h"
/***************************************************************
文件名: pwmdriver.c
作者: Doreen
版本: V1.0 2024/01/04
描述: pwm (led)驱动文件
博客：https://blog.csdn.net/weixin_47841246?spm=1000.2115.3001.5343
知乎: https://www.zhihu.com/people/fen-dou-de-nian-qing-ren-1
论坛: http://www.myfpga.org
***************************************************************/
/* 寄存器物理地址 */
#define H2F_LW_BASE_ADDR (0xFF200000)
//#define PWM_BASE 0x6000
#define MAP_PWM_ADDR (H2F_LW_BASE_ADDR + PWM_BASE)
#define PWM_SPAN 16
/* 映射后的寄存器虚拟地址指针 */
static void __iomem *LWH2F_bridge_addr;
/* pwm设备结构体 */
struct pwm_dev{
dev_t devid; /* 设备号 */
struct cdev cdev; /* cdev */
struct class *class; /* 类 */
struct device *device; /* 设备 */
int major; /* 主设备号 */
int minor; /* 次设备号 */
//unsigned int cnt_freq; /*pwm频率寄存器*/
//unsigned int cnt_duty; /*pwm占空比寄存器*/
};
struct pwm_dev pwm; /* pwm设备 */
/*定义设备名称*/
#define DEVICE_NAME "pwm"
static int pwm_open(struct inode *inode, struct file *filp )
{
//try_module_get(THIS_MODULE);
filp->private_data = &pwm; /* 设置私有数据 */
// printk(KERN_WARNING "pwm_open()\r\n");
return 0;
}
static int pwm_release(struct inode *inode, struct file *filp )
{
// module_put(THIS_MODULE);
filp->private_data = NULL;
//printk("pwm_close()\n");
return 0;
}
ssize_t pwm_read(struct file *filp, char *buf, size_t count,loff_t *f_pos)
{
int ret,register_data_1,register_data_2;
char char_data[32];
//printk("kernel pwm_read\n");
register_data_1 = ioread32(LWH2F_bridge_addr + 0);/*读 PWM 寄存器0，即 cnt_freq 寄存器*/
register_data_2 = ioread32(LWH2F_bridge_addr + 4);/*读 PWM 寄存器1，即 cnt_duty 寄存器*/
/*将读取到的数据拷贝到用户空间*/
sprintf(char_data,"%d %d",register_data_1,register_data_2);
ret = copy_to_user(buf, char_data, sizeof(char_data));
printk("register_data_1 = %d; copy_to_user = %s; \n",register_data_1,char_data);
if (ret !=0)
{
return -EFAULT;
}
//printk("read done\n");
return count;
}
ssize_t pwm_write(struct file *filp, const char *buf, size_t count, loff_t *f_pos)
{
int ret;
int data_1;
int data_2;
char char_data[32]="";
//printk("kernel pwm_write\n");
/*从用户空间将数据拷贝到 char_data 数组中*/
ret=copy_from_user(char_data, buf, 32);
printk("copy_from_user=%s \n",char_data);
if (ret !=0)
{
return -EFAULT;
}
sscanf(char_data,"%d %d",&data_1,&data_2);
iowrite32(data_1, LWH2F_bridge_addr + 0);/*写 PWM 寄存器 0，即 cnt_freq 寄存器*/
iowrite32(data_2, LWH2F_bridge_addr + 4);/*写 PWM 寄存器 1，即 cnt_duty 寄存器*/
printk("kernel set pwm_freq:%d; pwm_duty:%d\n",data_1, data_2);
//printk("write done\n");
return count;
}
/*定义驱动程序操作函数*/
struct file_operations pwm_fops =
{
.owner = THIS_MODULE,
.open = pwm_open,
.write = pwm_write,
.read = pwm_read,
.release = pwm_release,
};
/* 驱动入口函数 */
static int __init pwm_init(void)
{
// u32 val = 0;
int ret;
LWH2F_bridge_addr = ioremap_nocache(MAP_PWM_ADDR, PWM_SPAN);
/* 注册字符设备驱动 */
/* 1、创建设备号 */
if (pwm.major) { /* 定义了设备号 */
pwm.devid = MKDEV(pwm.major, 0);
ret = register_chrdev_region(pwm.devid, 1, DEVICE_NAME);
if(ret < 0) {
pr_err("cannot register %s char driver [ret=%d]\n",DEVICE_NAME, 1);
goto fail_map;
}
} else { /* 没有定义设备号 */
ret = alloc_chrdev_region(&pwm.devid, 0, 1, DEVICE_NAME); /* 申请设备号 */
if(ret < 0) {
pr_err("%s Couldn't alloc_chrdev_region, ret=%d\r\n", DEVICE_NAME, ret);
goto fail_map;
}
pwm.major = MAJOR(pwm.devid); /* 获取分配号的主设备号 */
pwm.minor = MINOR(pwm.devid); /* 获取分配号的次设备号 */
}
printk(KERN_ERR "pwm major=%d,minor=%d\r\n",pwm.major, pwm.minor);
/* 2、初始化cdev */
pwm.cdev.owner = THIS_MODULE;
cdev_init(&pwm.cdev, &pwm_fops);
/* 3、添加一个cdev */
ret = cdev_add(&pwm.cdev, pwm.devid, 1);
if(ret < 0)
goto del_unregister;
/* 4、创建类 */
pwm.class = class_create(THIS_MODULE, "pwm");
if (IS_ERR(pwm.class)) {
goto del_cdev;
}
/* 5、创建设备 */
pwm.device = device_create(pwm.class, NULL, pwm.devid, NULL, DEVICE_NAME);
if (IS_ERR(pwm.device)) {
goto destroy_class;
}
return 0;
/* 注销字符设备 */
del_cdev:
cdev_del(&pwm.cdev);
/* 销毁类 */
destroy_class:
class_destroy(pwm.class);
/* 注销设备号 */
del_unregister:
unregister_chrdev_region(pwm.devid, 1);
/* 释放内存映射 */
fail_map:
iounmap(LWH2F_bridge_addr);/*取消虚拟地址映射*/
return -EIO;
}
/*驱动出口函数*/
static void __exit pwm_exit(void)
{
/* 取消映射 */
iounmap(LWH2F_bridge_addr);
/* 注销字符设备 */
cdev_del(&pwm.cdev);
/* 注销设备号 */
unregister_chrdev_region(pwm.devid, 1);
/* 销毁设备 */
device_destroy(pwm.class, pwm.devid);
/* 销毁类 */
class_destroy(pwm.class);
}
module_init(pwm_init);
module_exit(pwm_exit);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Doreen");
应用程序设计：
#include "stdio.h"
#include "unistd.h"
#include "sys/types.h"
#include "sys/stat.h"
#include "fcntl.h"
#include "stdlib.h"
#include "string.h"
/***************************************************************
文件名 : pwmdriver_app.c
作者 : Doreen
版本 : V1.0
描述 : pwm 测试 应用程序。
使用方法 ：./pwmdriver_pp /dev/pwm 400000 200000
（第三个400000是pwm波频率 第四个参数200000 是pwm占空比 50%）
博客：https://blog.csdn.net/weixin_47841246?spm=1000.2115.3001.5343
知乎: https://www.zhihu.com/people/fen-dou-de-nian-qing-ren-1
论坛: http://www.myfpga.org
***************************************************************/
/*
* @description : main 主程序
* @param - argc : argv 数组元素个数
* @param - argv : 具体参数
* @return : 0 成功;其他 失败
*/
int main(int argc, char *argv[])
{
int ret = 0;
int fd = 0;
char *filename;
char data_w[32]="";
//char *data_w[2];
char data_r[32];
if(argc != 4){
printf("Error Usage!\r\n");
return -1;
}
filename = argv[1];
//data_w[0] = argv[2];
//data_w[1] = argv[3];
/* 打开 pwm 驱动 */
fd = open(filename, O_RDWR);
if(fd < 0){
printf("file %s open failed!\r\n", argv[1]);
return -1;
}
/*调用read方法读取/dev/pwm设备的寄存器数据到用户空间的data数组中*/
/* 向/dev/pwm 文件写入数据 */
strcat(data_w,argv[2]);
strcat(data_w," ");
strcat(data_w,argv[3]);
printf("parameters from command are = %s\r\n",data_w);
ret = write(fd, data_w, sizeof(data_w));
if(ret < 0){
printf("User write Failed!\r\n");
close(fd);
return -1;
}
else {/*打印你写入的数据*/
printf("write successfully\r\n");
}
usleep( 100*1000 );
/* 从/dev/pwm 文件读出数据 */
ret = read(fd,data_r,32);
if(ret < 0){
printf("read error \n");
return -1;}
else {/*打印读取到的数据*/
//printf("read_byte_number:%d; \r\n",ret);
printf("user read %s;\r\n",data_r);
//printf("Read pwm_freq:%s; pwm_duty:%s;\r\n",data_r[0],data_r[1]);
}
/* 关闭文件 */
ret = close(fd);
if(ret < 0){
printf("file %s close failed!\r\n", argv[1]);
return -1;
}
return 0;
}
标签：随意,PWM,ret,char,include,cdev,占空比,pwm,data From： https://www.cnblogs.com/DoreenLiu/p/17994578