Mini2440开发板PWM驱动与测试程序简要详解
发布时间：2021-11-21 21:27:12 所属栏目：教程 来源：互联网
导读：先看下电路原理图 #include linux/module.h #include linux/kernel.h #include linux/fs.h #include linux/init.h #include linux/delay.h #include linux/poll.h #include linux/interrupt.h #include linux/gpio.h #include asm/irq.h #include asm/io.h #
|
先看下电路原理图 #include <linux/module.h> #include <linux/kernel.h> #include <linux/fs.h> #include <linux/init.h> #include <linux/delay.h> #include <linux/poll.h> #include <linux/interrupt.h> #include <linux/gpio.h> #include <asm/irq.h> #include <asm/io.h> #include <asm/uaccess.h> #include <mach/regs-gpio.h> #include <mach/hardware.h> #include <plat/regs-timer.h> #include <mach/regs-irq.h> #include <asm/mach/time.h> #include <linux/clk.h> #include <linux/cdev.h> #include <linux/device.h> #include <linux/miscdevice.h> #define DEVICE_NAME "pwm" #define PWM_IOCTL_SET_FREQ 1 //设置pwm的频率 #define PWM_IOCTL_STOP 0 //停止pwm static struct semaphore lock; //定义信号量，此处的信号量是一个互斥信号量，用于PWM设备之多只能被一个进程打开 /* freq: pclk/50/16/65536 ~ pclk/50/16 * if pclk = 50MHz, freq is 1Hz to 62500Hz * human ear : 20Hz~ 20000Hz */ static void PWM_Set_Freq( unsigned long freq ) { unsigned long tcon; unsigned long tcnt; unsigned long tcfg1; unsigned long tcfg0; struct clk *clk_p; unsigned long pclk; //set GPB0 as tout0, pwm output s3c2410_gpio_cfgpin(S3C2410_GPB(0), S3C2410_GPB0_TOUT0);//功能配置 tcon = __raw_readl(S3C2410_TCON); //获得定时器控制寄存器的数值 tcfg1 = __raw_readl(S3C2410_TCFG1); //获得定时器配置寄存器0的值 tcfg0 = __raw_readl(S3C2410_TCFG0); //获得定时器配置寄存器1的值 //prescaler = 50 tcfg0 &= ~S3C2410_TCFG_PRESCALER0_MASK; tcfg0 |= (50 - 1); //mux = 1/16 tcfg1 &= ~S3C2410_TCFG1_MUX0_MASK; tcfg1 |= S3C2410_TCFG1_MUX0_DIV16; __raw_writel(tcfg1, S3C2410_TCFG1); __raw_writel(tcfg0, S3C2410_TCFG0); clk_p = clk_get(NULL, "pclk"); pclk = clk_get_rate(clk_p); tcnt = (pclk/50/16)/freq; __raw_writel(tcnt, S3C2410_TCNTB(0)); __raw_writel(tcnt/2, S3C2410_TCMPB(0)); tcon &= ~0x1f; tcon |= 0xb; //disable deadzone, auto-reload, inv-off, update TCNTB0&TCMPB0, start timer 0 __raw_writel(tcon, S3C2410_TCON); tcon &= ~2; //clear manual update bit __raw_writel(tcon, S3C2410_TCON); } static void PWM_Stop(void) { s3c2410_gpio_cfgpin(S3C2410_GPB(0), S3C2410_GPIO_OUTPUT); s3c2410_gpio_setpin(S3C2410_GPB(0), 0); } static int s3c24xx_pwm_open(struct inode *inode, struct file *file) { if (!down_trylock(&lock))//判断是否设备已经打开，已打开返回EBUSY return 0; else return -EBUSY; } static int s3c24xx_pwm_close(struct inode *inode, struct file *file) { PWM_Stop();//停止PWM up(&lock);//释放信号量 return 0; } static int s3c24xx_pwm_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg) { //printk("ioctl pwm: %x %lxn", cmd, arg); switch (cmd) { case PWM_IOCTL_SET_FREQ: if (arg == 0) return -EINVAL; PWM_Set_Freq(arg); break; case PWM_IOCTL_STOP: PWM_Stop(); break; } return 0; } static struct file_operations dev_fops = { .owner = THIS_MODULE, .open = s3c24xx_pwm_open, .release = s3c24xx_pwm_close, .ioctl = s3c24xx_pwm_ioctl, }; static struct miscdevice misc = { .minor = MISC_DYNAMIC_MINOR, .name = DEVICE_NAME, .fops = &dev_fops, }; static int __init dev_init(void) { int ret; init_MUTEX(&lock); ret = misc_register(&misc); printk (DEVICE_NAME"tinitializedn"); return ret; } static void __exit dev_exit(void) { misc_deregister(&misc); } module_init(dev_init); module_exit(dev_exit); MODULE_LICENSE("GPL"); MODULE_AUTHOR("FriendlyARM Inc."); MODULE_DESCRIPTION("S3C2410/S3C2440 PWM Driver");  （编辑：江门站长网） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |
