mini6410 PWM驱动程序:

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#include
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#include
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#define DEVICE_NAME "pwm"

#define PWM_IOCTL_SET_FREQ 1
#define PWM_IOCTL_STOP 0

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 )
{
unsigned long tcon;
unsigned long tcnt;
unsigned long tcfg1;
unsigned long tcfg0;

struct clk *clk_p;
unsigned long pclk;

unsigned tmp;

tmp = readl(S3C64XX_GPFCON);
tmp &= ~(0x3U << 28);
tmp |= (0x2U << 28);
writel(tmp, S3C64XX_GPFCON);

tcon = __raw_readl(S3C_TCON);
tcfg1 = __raw_readl(S3C_TCFG1);
tcfg0 = __raw_readl(S3C_TCFG0);

//prescaler = 50
tcfg0 &= ~S3C_TCFG_PRESCALER0_MASK;
tcfg0 |= (50 - 1);

//mux = 1/16
tcfg1 &= ~S3C_TCFG1_MUX0_MASK;
tcfg1 |= S3C_TCFG1_MUX0_DIV16;

__raw_writel(tcfg1, S3C_TCFG1);
__raw_writel(tcfg0, S3C_TCFG0);

clk_p = clk_get(NULL, "pclk");
pclk = clk_get_rate(clk_p);
tcnt = (pclk/50/16)/freq;

__raw_writel(tcnt, S3C_TCNTB(0));
__raw_writel(tcnt/2, S3C_TCMPB(0));

tcon &= ~0x1f;
tcon |= 0xb; //disable deadzone, auto-reload, inv-off, update TCNTB0&TCMPB0, start timer 0
__raw_writel(tcon, S3C_TCON);

tcon &= ~2; //clear manual update bit
__raw_writel(tcon, S3C_TCON);
}

void PWM_Stop( void )
{
unsigned tmp;
tmp = readl(S3C64XX_GPFCON);
tmp &= ~(0x3U << 28);
writel(tmp, S3C64XX_GPFCON);
}

static int s3c64xx_pwm_open(struct inode *inode, struct file *file)
{
if (!down_trylock(&lock))
return 0;
else
return -EBUSY;
}

static int s3c64xx_pwm_close(struct inode *inode, struct file *file)
{
up(&lock);
return 0;
}

static int s3c64xx_pwm_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
{
switch (cmd) {
case PWM_IOCTL_SET_FREQ:
if (arg == 0)
return -EINVAL;
PWM_Set_Freq(arg);
break;

case PWM_IOCTL_STOP:
default:
PWM_Stop();
break;
}

return 0;
}

static struct file_operations dev_fops = {
.owner = THIS_MODULE,
.open = s3c64xx_pwm_open,
.release = s3c64xx_pwm_close,
.ioctl = s3c64xx_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"\tinitialized\n");
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("S3C6410 PWM Driver");