EVM PWM.c
<per>
// PWM driver - Andrew Armstrong 2007
// Used a skeleton from somewhere, cannot remember where tho!
- include <linux/config.h>
- include <linux/kernel.h>
- include <linux/module.h>
- include <linux/init.h>
- include <linux/fs.h>
- include <linux/major.h>
- include <linux/root_dev.h>
- include <asm/uaccess.h> /* for put_user */
- include <asm/setup.h>
- include <asm/semaphore.h>
- include <asm/hardware/clock.h>
- include <asm/io.h>
- include <asm/mach-types.h>
- include <asm/mach/arch.h>
- include <asm/mach/map.h>
- include <asm/arch/hardware.h>
/*
* Prototypes - this would normally go in a .h file
*/
int init_module(void);
void cleanup_module(void);
static int device_open(struct inode *, struct file *);
static int device_release(struct inode *, struct file *);
static ssize_t device_read(struct file *, char *, size_t, loff_t *);
static ssize_t device_write(struct file *, const char *, size_t, loff_t *);
- define SUCCESS 0
- define DEVICE_NAME "fb3_pwm" /* Dev name as it appears in /proc/devices */
- define BUF_LEN 80 /* Max length of the message from the device */
/*
* Global variables are declared as static, so are global within the file.
*/
static int Major; /* Major number assigned to our device driver */
static int Device_Open = 0; /* Is device open?
* Used to prevent multiple access to device */
static char msg[BUF_LEN]; /* The msg the device will give when asked */
static char *msg_Ptr;
static struct file_operations fops = {
.read = device_read,
.write = device_write,
.open = device_open,
.release = device_release
};
//********************************************************************************
static int PWMStatus=1; //1 = on 2 = off
//********************************************************************************
- define PWM0_BASE __REG(0x01C22000)
- define PWM0_PID __REG(0x01C22000)
- define PWM0_PCR __REG(0x01C22004)
- define PWM0_CFG __REG(0x01C22008)
- define PWM0_START __REG(0x01C2200C)
- define PWM0_RPT __REG(0x01C22010)
- define PWM0_PER __REG(0x01C22014)
- define PWM0_PH1D __REG(0x01C22018)
void pwm_power(int option)
{
if(option==0)
{
PWM0_CFG = 0x00000000;
PWMStatus = 0;
}
else
{
PWM0_PCR = 0x00000001;
PWM0_CFG = 0x00000001;
PWM0_RPT = 0x99999999;
PWM0_PER = 0x00002000;
PWM0_PH1D = 0x00001000;
PWM0_START = 0x00000001;
PWMStatus = 1;
}
}
//AA07 Checks a character for a boolean 0 or 1 returns appropriately, returns 999 on error
int checkchar(char s)
{
if (s >= '0' && s <= '1')
{
if (s == '0')
{
return 0;
}
else
{
return 1;
}
}
else
{
return 999;
}
}
int init_module(void)
{
Major = register_chrdev(0, DEVICE_NAME, &fops);
if (Major < 0) {
printk(KERN_ALERT "Registering char device failed with %d\n", Major);
return Major;
}
printk(KERN_INFO "Create driver node:- 'mknod /dev/%s c %d 0'.\n", DEVICE_NAME, Major);
printk(KERN_INFO "[cat] to see status and [echo 0] for off and [1] for on\n");
printk(KERN_ALERT "Turning PWM on (default setting)\n");
pwm_power(0);
pwm_power(1);
return 0;
}
/*
* This function is called when the module is unloaded
*/
void cleanup_module(void)
{
/*
* Unregister the device
*/
int ret = unregister_chrdev(Major, DEVICE_NAME);
if (ret < 0)
printk(KERN_ALERT "Error in unregister_chrdev: %d\n", ret);
}
/*
* Methods
*/
/*
* Called when a process tries to open the device file, like
* "cat /dev/mycharfile"
*/
static int device_open(struct inode *inode, struct file *file)
{
if (Device_Open)
return -EBUSY;
Device_Open++;
sprintf(msg, "%d\n", PWMStatus);
msg_Ptr = msg;
try_module_get(THIS_MODULE);
return SUCCESS;
}
/*
* Called when a process closes the device file.
*/
static int device_release(struct inode *inode, struct file *file)
{
Device_Open--; /* We're now ready for our next caller */
/*
* Decrement the usage count, or else once you opened the file, you'll
* never get get rid of the module.
*/
module_put(THIS_MODULE);
return 0;
}
/*
* Called when a process, which already opened the dev file, attempts to
* read from it.
*/
static ssize_t device_read(struct file *filp, /* see include/linux/fs.h */
char *buffer, /* buffer to fill with data */
size_t length, /* length of the buffer */
loff_t * offset)
{
/*
* Number of bytes actually written to the buffer
*/
int bytes_read = 0;
/*
* If we're at the end of the message,
* return 0 signifying end of file
*/
if (*msg_Ptr == 0)
return 0;
/*
* Actually put the data into the buffer
*/
while (length && *msg_Ptr) {
/*
* The buffer is in the user data segment, not the kernel
* segment so "*" assignment won't work. We have to use
* put_user which copies data from the kernel data segment to
* the user data segment.
*/
put_user(*(msg_Ptr++), buffer++);
length--;
bytes_read++;
}
/*
* Most read functions return the number of bytes put into the buffer
*/
return bytes_read;
}
/*
* Called when a process writes to dev file: echo "hi" > /dev/hello
*/
static ssize_t
device_write(struct file *filp, const char *buff, size_t len, loff_t * off)
{
int i = checkchar(buff[0]);
if (i == 999)
{
printk(KERN_ALERT "Error in option, use 0 (off) or 1 (on)\n");
}
else
{
printk(KERN_ALERT "Setting value %d :- 0 (off) or 1 (on)\n",i);
pwm_power(i);
}
return len;
}
</per>
