基于xilinx平台的lcd pwm背光驱动开发

平台的lcd pwm背光驱动开发"/>

基于xilinx平台的lcd pwm背光驱动开发

1.驱动层

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <asm/io.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/miscdevice.h>
#include <linux/ioport.h>
#include <linux/of.h>
#include <linux/uaccess.h>
#include <linux/interrupt.h>
#include <asm/irq.h>
#include <linux/irq.h>
#include <asm/uaccess.h>
#include <linux/dma-mapping.h>//ax_pwm@80000000
#define AX_PWM_ADDR            (0X80000000)volatile unsigned int  * ax_pwm_freq_addr;
volatile unsigned int  * ax_pwm_duty_addr;dma_addr_t axidma_handle;
volatile unsigned int * axidma_addr;int major;static struct class *pwm_class   = NULL;static int pwm_open(struct inode *inode,struct file *file);
static ssize_t pwm_write(struct file *file,const char __user *buf, size_t count,loff_t *ppos);
static ssize_t pwm_read(struct file *file,char __user *buf,size_t size,loff_t *ppos);
/**file_operations 结构数据，沟通内核与操作系统桥梁** */
static struct file_operations pwm_lops=
{
.owner = THIS_MODULE,
.read  = pwm_read,
.open  = pwm_open,
.write = pwm_write,
};
/** 初始化，用于module init** */
static int __init pwm_init(void)
{major=register_chrdev(0,"pwm_dev",&pwm_lops);pwm_class= class_create(THIS_MODULE,"pwm_dev");device_create(pwm_class,NULL,MKDEV(major,0),NULL,"pwm_dev");printk("major dev number= %d",major);ax_pwm_freq_addr  =  ioremap(AX_PWM_ADDR   + 0x0, 4);ax_pwm_duty_addr  =  ioremap(AX_PWM_ADDR   + 0x04, 4);printk("ax_pwm_freq_addr=%0x04\n",ax_pwm_freq_addr);printk("ax_pwm_duty_addr=%0x04\n",ax_pwm_duty_addr);return 0;
}/**退出 用于 module exit** */
static void __exit pwm_exit(void)
{unregister_chrdev(major,"pwm_dev");device_destroy(pwm_class,MKDEV(major,0));class_destroy(pwm_class);iounmap(ax_pwm_duty_addr);iounmap(ax_pwm_freq_addr);}
/**open 接口函数** */
static int pwm_open(struct inode *inode,struct file *file)
{int err;printk("pwm open\n");return 0;
}
/** write 接口函数** */
static ssize_t pwm_write(struct file *file,const char __user *buf, size_t count,loff_t *ppos)
{printk("pwm write start !\n");char*after;unsigned long para = 0;para = simple_strtoul(buf,&after,10);printk("para=%ld\n",para);para = 100 - para;unsigned int freq_val = (unsigned int)((4294967296.0 / 100000000) * 500);//unsigned int duty     = (unsigned int)(4294967296 * para);//有变量，就不能有小数unsigned int duty = 4294967296 * para / 100;printk("duty=%ld\n",duty);//0是最亮，所以是1-percent. add by iverson.deng 2023/9/13//unsigned int duty     = (unsigned int)(4294967296 * 0.95);iowrite32(freq_val,ax_pwm_freq_addr);iowrite32(duty,ax_pwm_duty_addr);printk("dma write is over!\n");return 0;
}/** read 接口函数*DMA读取数据是按照32bit读取的* */
static ssize_t pwm_read(struct file *file,char __user *buf,size_t size,loff_t *ppos)
{return 0;
}module_init(pwm_init);
module_exit(pwm_exit);MODULE_AUTHOR("iverson@pwm");
MODULE_DESCRIPTION("pwm driver");
MODULE_ALIAS("linux axi pwm driver");
MODULE_LICENSE("GPL");

交叉编译 Makefile

modname:=pwm_driver
obj-m:=$(modname).oPWD :=$(shell pwd)
MAKE :=make
KERNELDIR = /home/iversondeng/workspace/alinx/petalinux/ubootandkernel/linux-xlnx-xilinx-v2020.1
CROSS_COMPILE=aarch64-xilinx-linux-
ARCH=arm64all:$(MAKE) ARCH=$(ARCH) CROSS_COMPILE=$(CROSS_COMPILE) -C $(KERNELDIR) M=$(PWD) modulesclean:rm -rf $(modname).ko *.o *mod* \.*cmd *odule* .tmp_versions.PHONY: all clean

2.应用层测试

#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>void delay(void)
{int i,j;for(i=0;i<20000;i++)for(j=0;j<10000;j++);
}unsigned int readarray[128];int main(int argc , char ** argv)
{int fd;int i = 0;int j = 0;fd = open("/dev/pwm_dev",O_RDWR);if(fd < 0) {printf("can not open file\n");while(1);}else{ printf("open file sucuss\n");}delay();if(argc <= 1) return;    j = atoi(argv[1]);if(!(j >= 0 && j <= 100)) return;write(fd,argv[1],1);close(fd);printf("pwm test over!\n");return 0;
}

交叉编译

$CC  pwm_test.c -o pwm_test -O2 -w