mini2440 pmw驱动-linux3.10.59

/* linux/drivers/char/mini2440_pwm.c
*	Copyright (c) 2013 Feng Guoqing
*
* mini2440 PWM Driver
*
* This file is subject to the terms and conditions of the GNU General Public
* License.  See the file COPYING in the main directory of this archive for
* more details.
*
*/

#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
#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 ) //??pwm???,???????
{
unsigned long tcon;
unsigned long tcnt;
unsigned long tcfg1;
unsigned long tcfg0;
struct clk *clk_p;
unsigned long pclk;

s3c_gpio_cfgpin(S3C2410_GPB(0), S3C2410_GPB0_TOUT0);
tcon = __raw_readl(S3C2410_TCON);
tcfg1 = __raw_readl(S3C2410_TCFG1);
tcfg0 = __raw_readl(S3C2410_TCFG0);
tcfg0 &= ~S3C2410_TCFG_PRESCALER0_MASK;
tcfg0 |= (50 - 1);
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)
{
s3c_gpio_cfgpin(S3C2410_GPB(0), S3C2410_GPIO_OUTPUT);
gpio_set_value(S3C2410_GPB(0), 0);
}

static int s3c24xx_pwm_open(struct inode *inode, struct file *file)
{
if (!down_trylock(&lock)){
return 0;
} else {
return -EBUSY;
}
}

static int s3c24xx_pwm_close(struct inode *inode, struct file *file)
{
PWM_Stop();
up(&lock);
return 0;
}

static long s3c24xx_pwm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
switch (cmd) {
case PWM_IOCTL_SET_FREQ: //if cmd=1 ???case PWM_IOCTL_SET_FREQ
if (arg == 0)
return -EINVAL;
PWM_Set_Freq(arg);
break;
case PWM_IOCTL_STOP:  // if cmd=2 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,
.unlocked_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;
sema_init(&lock, 1);
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("S3C2410/S3C2440 PWM Driver");