pcDuino Linux驱动开发五 -- 最简单的PWM驱动

tjcfeng · 发表于 2014-11-30 23:14:22

其实比较来说，PWM比中断还要简单，只不过一般刚接触的板子首先实现的都是基本的IO，所以把PWM安排在了中断之后。为了不使帖子看起来内容太少，这个程序将两路PWM 放在了一起，不过也是多了几个寄存器的设置而已。
另外要吐槽一下A10，PWM少就不说什么了，居然计数寄存器只有8位。是的，只有8位，最大到255而已，这个也太弱了吧

还有预分频，也只有这么几个

看到0101...0111那几个了吗？经过尝试后，发现其实是起作用的，是/720、/840、/960，后面的1101...1111是84K、96K、108K，权当一点补偿吧。
下面上程序，跟GPIO的一样，还是精简得不能再精简了。接线方式没来得及拍照，后面补上。

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/wait.h>
#include <linux/delay.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include "../A10.h"
/**********************************************************************/
#define PWM_CH0 2
volatile static unsigned long* REG_PB_CFG0;
volatile static unsigned long* REG_PI_CFG0;
volatile static unsigned long* REG_PWM_CTRL_REG;
volatile static unsigned long* REG_PWM_CH0_PERIOD;
volatile static unsigned long* REG_PWM_CH1_PERIOD;
static int Inited = 0;
static int PWM_open(struct inode* n, struct file* f)
{
int Result = 0;
Inited++;
if (Inited > 1)
{
return 0;
}
REG_PB_CFG0 = (volatile unsigned long*) ioremap(PB_CFG0, 4);
REG_PI_CFG0 = (volatile unsigned long*) ioremap(PI_CFG0, 4);
REG_PWM_CTRL_REG = (volatile unsigned long*) ioremap(PWM_CTRL_REG, 4);
REG_PWM_CH0_PERIOD= (volatile unsigned long*) ioremap(PWM_CH0_PERIOD, 4);
REG_PWM_CH1_PERIOD= (volatile unsigned long*) ioremap(PWM_CH1_PERIOD, 4);
*REG_PB_CFG0 &= ~(0x7 << 8) ;
*REG_PB_CFG0 |= (0x2 << 8) ; //PWM0
*REG_PI_CFG0 &= ~(0x7 << 12) ;
*REG_PI_CFG0 |= (0x2 << 12) ; //PWM1
*REG_PWM_CH0_PERIOD = (249 << 16) + 5;
*REG_PWM_CTRL_REG |= (0xF << 0);
*REG_PWM_CTRL_REG |= (0x0 << 8) + (0x0 << 7) + (0x1 << 6) + (0x0 << 5);
*REG_PWM_CTRL_REG |= (0x1 << 4);
*REG_PWM_CH1_PERIOD = (249 << 16) + 5;
*REG_PWM_CTRL_REG |= (0x8 << 15);
*REG_PWM_CTRL_REG |= (0x0 << 23) + (0x0 << 22) + (0x1 << 21) + (0x1 << 20);
*REG_PWM_CTRL_REG |= (0x1 << 19);
printk("Open Finished!\n");
return Result;
}
static ssize_t PWM_write(struct file* f, const char __user* buf, size_t len, loff_t* l)
{
//printk("Write Finished!\n");
return 0;
}
static ssize_t PWM_read(struct file* f, char __user* buf, size_t len, loff_t* l)
{
//printk("Read Finished!\n");
return 0;
}
static int PWM_close(struct inode* n, struct file* f)
{
Inited--;
if (Inited > 0)
{
return 0;
}
*REG_PWM_CTRL_REG = 0;
*REG_PWM_CH0_PERIOD = 0;
*REG_PWM_CH1_PERIOD = 0;
iounmap(REG_PB_CFG0);
iounmap(REG_PI_CFG0);
iounmap(REG_PWM_CTRL_REG);
iounmap(REG_PWM_CH0_PERIOD);
iounmap(REG_PWM_CH1_PERIOD);
printk("Close Finished!\n");
return 0;
}
/**********************************************************************/
#define DEV_NAME &quotWM"
#define DEV_COUNT 1
static struct class* pClass;
int major;
static struct file_operations fops =
{
.owner = THIS_MODULE,
.open = PWM_open,
.write = PWM_write,
.read = PWM_read,
.release = PWM_close,
};
static int __init PWM_init(void)
{
major = register_chrdev(0, DEV_NAME, &fops);
pClass = class_create(THIS_MODULE, DEV_NAME);
if (pClass == NULL)
{
unregister_chrdev(major, DEV_NAME);
return -1;
}
device_create(pClass, NULL, MKDEV(major, 0), NULL, DEV_NAME);
PWM_open(NULL, NULL);
//printk("Init Finished!\n");
return 0;
}
static void __exit PWM_exit(void)
{
PWM_close(NULL, NULL);
unregister_chrdev(major, DEV_NAME);
if (pClass)
{
device_destroy(pClass, MKDEV(major, 0));
class_destroy(pClass);
}
//printk("Exit Finished!\n");
}
MODULE_LICENSE("GPL");
MODULE_AUTHOR("LiuYang");
module_init(PWM_init);
module_exit(PWM_exit);

pcDuino Linux驱动开发五 -- 最简单的PWM驱动

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