驱动开发-PWM控制LED

1、PWM控制LED一、 确定任务1、掌握基本的字符设备的驱动程序设计。2、掌握基本的文件操作。3、掌握在操作系统下的PWM驱动程序的原理。二、 学习内容 1、阅读S5PV210数据手册，熟悉PWM的原理。2、编写PWM输出的应用程序。3、编写makefile文件4、下载并调试PWM输出的应用程序。三、基础知识a) 原理图：b) 系统框架由该图可知，在选取了PCLK作为时钟源后，需经过8BIT PRESCALER0分频器，而后，经过1/1或1/2或1/4或1/8或1/16分频器后，送到逻辑控制电路（Control LogicX）后，被送到引脚输出。所以，对PWM的操作就是围绕设置时钟分频，得到合适

2、的频率，然后，设置逻辑控制电路得到合适的脉宽。c) 寄存器简介：寄存器TCFG0用于配置PWM的预分频比，TCFG015：8八位用于配置计时器2、3、4（timer2、timer3、timer4）的预分频值。TCFG07:0八位用于配置计时器0、1的预分频值。寄存器TCFG1用于配置PWM的分频比。PWM控制寄存器TCON，设置启动PWM，装载寄存器，输出反相及寄存器自动装载等功能。TCNTB1是timer1的定时器计数寄存器。TCMPB1是timer1的定时器比较寄存器。TCNTO1是timer1的定时器计数寄寄存器，可以从中读出当前计数寄存器中的值。四、代码设计 1、 PWM输出的原理：P

3、WM输出脚，默认为低电平，PWM计数器TCNTn的初始值等于TCNTBn，当TCNTn的值递减到等于TCMPBn的值时，PWM输出高电平，当PWM计数器的递减到0时，输出又变为低电平，如此周而复始。2、 驱动原理：该驱动实现为一个字符设备，通过ioctl函数来设置相关寄存器的值，以此来实现PWM波形的输出与禁止3、 驱动代码分析：（详细代码请查看附件）#include <linux/module.h>#include <linux/kernel.h>#include <linux/fs.h>#include <linux/init.h>#incl

4、ude <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>#in

5、clude <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>/*210平台头文件*/#include <linux/platform_device.h>#include <plat/gpio-cfg.h>#include <mach/gpio.h>#def

6、ine TCFG0 0xE2500000 #define TCFG1 0xE2500004 #define TCON 0xE2500008 #define TCNTB0 0xE250000C #define TCMPB0 0xE2500010 #define TCNTO0 0xE2500014#defineTCNTB1 0xE2500018 #define TCMPB1 0xE250001C #define TCNTO1 0xE2500020 /* 声明unsigned int指针* 用于保存寄存器映射后的地址*/unsigned int *rTCFG0; unsigned int *rTCF

7、G1; unsigned int *rTCON; unsigned int *rTCNTB0; unsigned int *rTCMPB0; unsigned int *rTCNTO0; unsigned int *rTCNTB1; unsigned int *rTCMPB1; unsigned int *rTCNTO1; unsigned long tcnt;#define DEVICE_NAME "pwm_led"#define PWM_IOCTL_SET_HOLLOW 0#define PWM_IOCTL_SET_FREQ 1static struct semapho

8、re lock;/ set_register( rGPH2CON , 0x1, 0xf , 0 );/* * 自定义set_register函数，作用如下：*mmap_addr = *mmap_addr &( ( clear_flag << pos );*mmap_addr = *mmap_addr | (value << pos);*/*mmap_addr:映射后寄存器地址 value:要设置的值 clear_flag:清除标志 pos:清除位置*/unsigned int set_register( unsigned int *mmap_addr , uns

9、igned int value ,unsigned int clear_flag ,unsigned char pos) unsigned int register_value_org; /寄存器原来的值 unsigned int register_value; /*读取寄存器的值*/ register_value = ioread32( mmap_addr ); register_value_org = register_value; /* * 清除register_value对应位的值 * 如：register_value = register_value & (0x3 <&

10、lt; 4); * 既是将register_value第4、5位清零 */ register_value = register_value & (clear_flag << pos); /*设置register_value对应位的值*/ register_value = register_value | value << pos; /*将register_value的值写入mmap_addr寄存器中*/ iowrite32( register_value , mmap_addr ); return register_value_org; /返回原来寄存器的值/*

11、 freq: pclk/50/16/65536 pclk/50/16 * if pclk = 50MHz, freq is 1Hz to 62500Hz * human ear : 20Hz 20000Hz */void PWM_Set_hollow(unsigned long hollow)/ unsigned int tcmpb0;/ unsigned int tcmpb1;/tcmpb0 = (hollow & 0xffff); /chj/tcmpb1 = (hollow & (0xffff<<16)>>16); /chj/ printk(&quo

12、t;<3>tcmpb0:%dn",tcmpb0);/ printk("<3>tcmpb1:%dn",tcmpb1);/ _raw_writel(tcmpb0, rTCMPB0);/ _raw_writel(tcmpb1, rTCMPB1);/* switch(hollow)case 2: _raw_writel(tcnt/2, rTCMPB1); break;case 4: _raw_writel(tcnt/4, rTCMPB1); break;case 8: _raw_writel(tcnt/8, rTCMPB1); break;case

13、 16: _raw_writel(tcnt/16, rTCMPB1); break;case 32: _raw_writel(tcnt/32, rTCMPB1); break;case 64: _raw_writel(tcnt/64, rTCMPB1); break;case 128: _raw_writel(tcnt/128, rTCMPB1); break;case 256: _raw_writel(tcnt/256, rTCMPB1); break;default:break;*/_raw_writel(tcnt/hollow, rTCMPB1); static void PWM_Set

14、_Freq( unsigned long freq )unsigned long tcon;unsigned long tcfg1;unsigned long tcfg0;struct clk *clk_p;unsigned long pclk;/set GPB0 as tout0, pwm output/s3c2410_gpio_cfgpin(S3C2410_GPB0, S3C2410_GPB0_TOUT0);/s3c2410_gpio_cfgpin(S3C2410_GPB1, S3C2410_GPB1_TOUT1);/chj/s3c_gpio_cfgpin(S5PV210_GPD0(0),

15、S3C_GPIO_SFN(2);s3c_gpio_cfgpin(S5PV210_GPD0(1),S3C_GPIO_SFN(2);/tcon = _raw_readl(S3C2410_TCON);/tcfg1 = _raw_readl(S3C2410_TCFG1);/tcfg0 = _raw_readl(S3C2410_TCFG0);tcon = _raw_readl(rTCON); tcfg1 = _raw_readl(rTCFG1); tcfg0 = _raw_readl(rTCFG0);/prescaler = 50/tcfg0 &= S3C2410_TCFG_PRESCALER0

16、_MASK;/tcfg0 |= (50 - 1); tcfg0 &= 0x00; tcfg0 |= (50 - 1); /mux = 1/16/tcfg1 &= 0x0000000f;tcfg1 &= (0x0000000f<<4); /chj/tcfg1 |= 0x00000003;tcfg1 |= 0x00000003<<4; /chj_raw_writel(tcfg1, rTCFG1);_raw_writel(tcfg0, rTCFG0);clk_p = clk_get(NULL, "pclk");pclk = clk_

17、get_rate(clk_p);tcnt = (pclk/50/8)/freq;/ printk("<3>pclk:%ldn",pclk);/ printk("<3>tcnt:%ldn",tcnt);/ printk("<3>tcnt:%ldn",tcnt);/_raw_writel(tcnt, rTCNTB0); _raw_writel(tcnt, rTCNTB1); /chj/_raw_writel(tcnt/2, rTCMPB0);_raw_writel(tcnt/2, rTCMPB1); /

18、chj tcon &= 0x10;tcon &= (0xf<<8); /chj/tcon |= 0xb; /disable deadzone, auto-reload, inv-on, update TCNTB0&TCMPB0, start timer 0tcon |= (0xf<<8); /chj_raw_writel(tcon, rTCON);/tcon &= 2; /clear manual update bittcon &=(2<<8); /chj_raw_writel(tcon, rTCON);static

19、void PWM_Stop(void)/s3c2410_gpio_cfgpin(S3C2410_GPB0, S3C2410_GPIO_OUTPUT);/s3c2410_gpio_cfgpin(S3C2410_GPB1, S3C2410_GPIO_OUTPUT); /chj/s3c2410_gpio_setpin(S3C2410_GPB0, 0);/s3c2410_gpio_setpin(S3C2410_GPB1, 0);/s3c_gpio_cfgpin(S5PV210_GPD0(0),S3C_GPIO_SFN(1); / s3c_gpio_cfgpin(S5PV210_GPD0(1),S3C_

20、GPIO_SFN(1);/s3c_gpio_setpin(S5PV210_GPD0(0), 0); / s3c_gpio_setpin(S5PV210_GPD0(1), 0);unsigned long tcon;tcon = _raw_readl(rTCON);tcon &= (0x1<<8); /chj_raw_writel(tcon, rTCON);static int s3c24xx_pwm_open(struct inode *inode, struct file *file)/*if (!down_trylock(&lock) return 0;else

21、 return -EBUSY;*/return 0;static int s3c24xx_pwm_close(struct inode *inode, struct file *file)PWM_Stop();/up(&lock); 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) ca

22、se PWM_IOCTL_SET_FREQ: if (arg = 0) return -EINVAL; PWM_Set_Freq(arg); break;case PWM_IOCTL_SET_HOLLOW: PWM_Set_hollow(arg); break;default: break;return 0;static struct file_operations dev_fops = .owner = THIS_MODULE, .open = s3c24xx_pwm_open, .release = s3c24xx_pwm_close, .ioctl = s3c24xx_pwm_ioctl

23、,;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");/*将GPIO的物理地址映射到内核空间中*/rTCFG0 = ioremap( TCFG0 , 4 ); rTCF

24、G1 = ioremap( TCFG1 , 4 ); rTCON = ioremap( TCON , 4 ); /rTCNTB0 = ioremap( TCNTB0 , 4 ); /rTCMPB0 = ioremap( TCMPB0 , 4 ); rTCNTB1 = ioremap( TCNTB1 , 4 );rTCMPB1 = ioremap( TCMPB1 , 4 ); /rTCNTO0 = ioremap( TCNTO0 , 4 ); rTCNTO1 = ioremap( TCNTO1 , 4 ); return ret;static void _exit dev_exit(void)PWM_Stop();/up(&lock);/*解除GPIO映射*/ iounmap(rTCFG0);iounmap(rTCFG1);iounmap(rTCON);/iounmap(rTCNTB0);/iounmap(rTCMPB0);iounmap(rTCNTB1);iounmap(rTCMPB1);/iounmap(rTCNTO0);iounmap(rTCNTO1);misc_deregister(&misc);module_init(dev_init);module_exit(dev_e