ARM蜂鸣器驱动..doc

在linux-2.6.32.2/drivers/char/目录下，增加一个驱动程序文件mini2440_pwm.c，内容如下： #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 //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 lock static 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tcon tcfg1 = __raw_readl(S3C2410_TCFG1); //读取寄存器TCFG1 到tcfg1 tcfg0 = __raw_readl(S3C2410_TCFG0); //读取寄存器TCFG0 到tcfg0 //prescaler = 50 tcfg0 = ~S3C2410_TCFG_PRESCALER0_MASK; // S3C2410_TCFG_PRESCALER0_MASK定时器0 和1 的预分频值的掩码，TCFG[0~8] tcfg0 |= (50 - 1); // 预分频为50 //mux = 1/16 tcfg1 = ~S3C2410_TCFG1_MUX0_MASK; //S3C2410_TCFG1_MUX0_MASK 定时器0 分割值的掩码：TCFG1[0~3] tcfg1 |= 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pclk pclk = 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, upda