ARM蜂鸣器驱动.doc

在linux-/drivers/char/目录下，增加一个驱动程序文件mini2440_pwm.c，内容如下：#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define DEVICE_NAME pwm /设备名#define PWM_IOCTL_SET_FREQ 1 /定义宏变量，用于后面的ioctl 中的switch case#define PWM_IOCTL_STOP 0 /定义信号量 lockstatic struct semaphore lock;/* 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 ) /设置pwm 的频率，配置各个寄存器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 设置GPB0 为tout0,pwm 输出s3c2410_gpio_cfgpin(S3C2410_GPB(0), S3C2410_GPB0_TOUT0);tcon = _raw_readl(S3C2410_TCON); /读取寄存器TCON 到tcontcfg1 = _raw_readl(S3C2410_TCFG1); /读取寄存器TCFG1 到tcfg1tcfg0 = _raw_readl(S3C2410_TCFG0); /读取寄存器TCFG0 到tcfg0/prescaler = 50tcfg0 &= S3C2410_TCFG_PRESCALER0_MASK; / S3C2410_TCFG_PRESCALER0_MASK定时器0 和1 的预分频值的掩码，TCFG08tcfg0 |= (50 - 1); / 预分频为50/mux = 1/16tcfg1 &= S3C2410_TCFG1_MUX0_MASK; /S3C2410_TCFG1_MUX0_MASK 定时器0 分割值的掩码：TCFG103tcfg1 |= S3C2410_TCFG1_MUX0_DIV16; /定时器0 进行16 分割_raw_writel(tcfg1, S3C2410_TCFG1); /把tcfg1 的值写到分割寄存器S3C2410_TCFG1 中_raw_writel(tcfg0, S3C2410_TCFG0); /把tcfg0 的值写到预分频寄存器S3C2410_TCFG0 中clk_p = clk_get(NULL, pclk); /得到pclkpclk = clk_get_rate(clk_p);tcnt = (pclk/50/16)/freq; /得到定时器的输入时钟，进而设置PWM 的调制频率_raw_writel(tcnt, S3C2410_TCNTB(0); /PWM 脉宽调制的频率等于定时器的输入时钟_raw_writel(tcnt/2, S3C2410_TCMPB(0); /占空比是50%tcon &= 0x1f;tcon|= 0xb; /disable deadzone, auto-reload, inv-off, update TCNTB0&TCMPB0, start timer 0_raw_writel(tcon, S3C2410_TCON); /把tcon 写到计数器控制寄存器S3C2410_TCON 中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); /设置GPB0 为输出s3c2410_gpio_setpin(S3C2410_GPB(0), 0); /设置GPB0 为低电平，使蜂鸣器停止static int s3c24xx_pwm_open(struct inode *inode, struct file *file)if (!down_trylock(&lock) /是否获得信号量，是down_trylock(&lock）=0，否则非0return 0;elsereturn -EBUSY; /返回错误信息：请求的资源不可用static int s3c24xx_pwm_close(struct inode *inode, struct file *file)PWM_Stop();up(&lock); /释放信号量lockreturn 0;/*cmd 是1，表示设置频率；cmd 是2 ，表示停止pwm*/static int s3c24xx_pwm_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)switch (cmd) case PWM_IOCTL_SET_FREQ: /if cmd=1 即进入case PWM_IOCTL_SET_FREQif (arg = 0) /如果设置的频率参数是0return -EINVAL; /返回错误信息，表示向参数传递了无效的参数PWM_Set_Freq(arg); /否则设置频率break;case PWM_IOCTL_STOP: / if cmd=2 即进入case PWM_IOCTL_STOPPWM_Stop(); /停止蜂鸣器break;return 0; /成功返回/*初始化设备的文件操作的结构体*/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); /初始化一个互斥锁ret = misc_register(&misc); /注册一个misc 设备printk (DEVICE_NAMEtinitializedn);return ret;static void _exit dev_exit(void)misc_deregister(&misc); /注销设备module_init(dev_init);module_exit(dev_exit);MODULE_LICENSE(GPL);MODULE_AUTHOR(FriendlyARM Inc.);MODULE_DESCRIPTION(S3C2410/S3C2440 PWM Driver);这里不说明怎么修改Makefile和Kconfig，将其编译进内核之后，下载到板子上，下面直接给出应用程序pwm.c：#include /标准输入输出定义#include /POSIX 终端控制定义#include /Unix 标准函数定义#include /标准函数库定义#define PWM_IOCTL_SET_FREQ 1#define PWM_IOCTL_STOP 0#define ESC_KEY 0x1b /定义ESC_KEY 为ESC 按键的键值static int getch(void) /定义函数在终端上获得输入，并把输入的量（int）返回struct termios oldt,newt; /终端结构体struct termiosint ch;if (!isatty(STDIN_FILENO) /判断串口是否与标准输入相连fprintf(stderr, this problem should be run at a terminaln);exit(1);/ save terminal settingif(tcgetattr(STDIN_FILENO, &oldt) 0) /获取终端的设置参数perror(save the terminal setting);exit(1);/ set terminal as neednewt = oldt;newt.c_lflag &= ( ICANON | ECHO ); /控制终端编辑功能参数ICANON 表示使用标准输入模式；参数ECH0 表示显示输入字符if(tcsetattr(STDIN_FILENO,TCSANOW, &newt) 0) /保存新的终端参数perror(set terminal);exit(1);ch = getchar();/ restore termial settingif(tcsetattr(STDIN_FILENO,TCSANOW,&oldt) 0) /恢复保存旧的终端参数perror(restore the termial setting);exit(1);return ch;static int fd = -1;static void close_buzzer(void);static void open_buzzer(void) /打开蜂鸣器fd = open(/dev/pwm, 0); /打开pwm 设备驱动文件if (fd = 0) ioctl(fd, PWM_IOCTL_STOP); /停止蜂鸣器close(fd); /关闭设备驱动文件fd = -1;static void set_buzzer_freq(int freq)/ this IOCTL command is the key to set frequencyint ret = ioctl(fd, PWM_IOCTL_SET_FREQ, freq); /设置频率if(ret 0) /如果输入的频率错误perror(set the frequency of the buzzer);exit(1); /退出，返回1static void stop_buzzer(void)int ret = ioctl(fd, PWM_IOCTL_STOP); /关闭蜂鸣器if(ret 0) /如果无法关闭蜂鸣器perror(stop the buzzer);exit(1); /退出返回1int main(int argc, char *argv)int freq = 1000 ;open_buzzer();/打开蜂鸣器printf( nBUZZER TEST ( PWM Control )n );printf( Press +/- to increase/reduce the frequency of the BUZZERn ) ;printf( Press ESC key to Exit this programnn );while( 1 )int ke