de2_lcd_16207.c

Altera DE2开发板的LED、LCD、SEG7和按键的linux下的设备驱动程序

/*
 *  lcd16207.c - Create an input/output character device
 *  not all functions are working. But they could be used in 
 *  future. 
 */

#include <linux/delay.h>
#include "de2_includes.h"
#include "de2_lcd_16207.h"

#define SUCCESS 0
//#define DEBUG 1

/* 
 * Is the device open right now? Used to prevent
 * concurent access into the same device 
 */
static int Device_Open = 0;

/* 
 * The message the device will give when asked 
 */
static char Message[BUF_LEN];

/* 
 * How far did the process reading the message get?
 * Useful if the message is larger than the size of the
 * buffer we get to fill in device_read. 
 */
static char *Message_Ptr;

/* 
 * This is called whenever a process attempts to open the device file 
 */
static int device_open(struct inode *inode, struct file *file)
{
#ifdef DEBUG
  printk(KERN_INFO "device_open(%p)\n", file);
#endif
  
  /* 
   * We don't want to talk to two processes at the same time 
   */
  if (Device_Open)
    return -EBUSY;
  
  Device_Open++;
  /*
   * Initialize the message 
   */
  Message_Ptr = Message;
  try_module_get(THIS_MODULE);
  return SUCCESS;
}

static int device_release(struct inode *inode, struct file *file)
{
#ifdef DEBUG
  printk(KERN_INFO "device_release(%p,%p)\n", inode, file);
#endif
  
  /* 
   * We're now ready for our next caller 
   */
  Device_Open--;
  
  module_put(THIS_MODULE);
  return SUCCESS;
}

/* 
 * This function is called whenever a process which has already opened the
 * device file attempts to read from it.
 */
static ssize_t device_read(struct file *file,	/* see include/linux/fs.h   */
			   char __user * buffer,	/* buffer to be
							 * filled with data */
			   size_t length,	/* length of the buffer     */
			   loff_t * offset)
{
  /* 
   * Number of bytes actually written to the buffer 
   */
  int bytes_read = 0;
  
#ifdef DEBUG
  printk(KERN_INFO "device_read(%p,%p,%d)\n", file, buffer, length);
#endif
  
  /* 
   * If we're at the end of the message, return 0
   * (which signifies end of file) 
   */
  if (*Message_Ptr == 0)
    return 0;
  
  /* 
   * Actually put the data into the buffer 
   */
  while (length && *Message_Ptr) {
    
    /* 
     * Because the buffer is in the user data segment,
     * not the kernel data segment, assignment wouldn't
     * work. Instead, we have to use put_user which
     * copies data from the kernel data segment to the
     * user data segment. 
     */
    put_user(*(Message_Ptr++), buffer++);
    length--;
    bytes_read++;
  }
  
#ifdef DEBUG
  printk(KERN_INFO "Read %d bytes, %d left\n", bytes_read, length);
#endif
  
  /* 
   * Read functions are supposed to return the number
   * of bytes actually inserted into the buffer 
   */
  return bytes_read;
}

/* 
 * This function is called when somebody tries to
 * write into our device file. 
 */
static ssize_t device_write(struct file *file,
			    const char __user * buffer, size_t length, loff_t * offset)
{
  int ii;
  unsigned char c;

#ifdef DEBUG
  printk(KERN_INFO "device_write(%p,%s,%d);\n", file, buffer, length);
#endif
  WriteNios(ADR_LCD_COMMAND,0x80);
  udelay(50);
  for (ii = 0; ii < length && ii < BUF_LEN; ii++)
    {
      get_user(c, buffer + ii);
      WriteNios(ADR_LCD_DATA, (unsigned long) c);
      udelay(50);
    }
 
 if (length < BUF_LEN)
    {
	     for (ii = length; ii < BUF_LEN; ii++)
		{
		  WriteNios(ADR_LCD_DATA,0x20);
		  udelay(50);
		}
	     WriteNios(ADR_LCD_COMMAND,0xC0);
	     udelay(50);
	     for (ii = BUF_LEN; ii < BUF_LEN+BUF_LEN; ii++)
		{
		  WriteNios(ADR_LCD_DATA,0x20);
		  udelay(50);
		}      
    }
  else
    {
      WriteNios(ADR_LCD_COMMAND,0xC0);
      udelay(50);
      for (ii = BUF_LEN; ii < length && ii < BUF_LEN+BUF_LEN; ii++)
		{
		  get_user(c, buffer + ii);
		  WriteNios(ADR_LCD_DATA,(unsigned long) c);
		  udelay(50);
		}
		  if (length < BUF_LEN + BUF_LEN)
		{
		  for (ii = length; ii < BUF_LEN + BUF_LEN; ii++)
			{
			  WriteNios(ADR_LCD_DATA, 0x20);
			  udelay(50);
			}
		}
    }
  
  /* 
   * Again, return the number of input characters used 
   */
  return length;
}

/* 
 * This function is called whenever a process tries to do an ioctl on our
 * device file. We get two extra parameters (additional to the inode and file
 * structures, which all device functions get): the number of the ioctl called
 * and the parameter given to the ioctl function.
 *
 * If the ioctl is write or read/write (meaning output is returned to the
 * calling process), the ioctl call returns the output of this function.
 *
 */
static int device_ioctl(struct inode *inode,	/* see include/linux/fs.h */
		 struct file *file,	/* ditto */
		 unsigned int ioctl_num,	/* number and param for ioctl */
		 unsigned long ioctl_param)
{
  int i;
  char *temp;
  char ch;
  
  /* 
   * Switch according to the ioctl called 
   */
  switch (ioctl_num) {
  case IOCTL_SET_MSG:
    /* 
     * Receive a pointer to a message (in user space) and set that
     * to be the device's message.  Get the parameter given to 
     * ioctl by the process. 
     */
    temp = (char *)ioctl_param;
    
    /* 
     * Find the length of the message 
     */
    get_user(ch, temp);
    for (i = 0; ch && i < BUF_LEN + BUF_LEN; i++, temp++)
      get_user(ch, temp);
    if (i<BUF_LEN)
      {
	i=i-1;
      }
    device_write(file, (char *)ioctl_param, i, 0);
    break;
    
  case IOCTL_GET_MSG:
    /* 
     * Give the current message to the calling process - 
     * the parameter we got is a pointer, fill it. 
     */
    i = device_read(file, (char *)ioctl_param, 99, 0);
    
    /* 
     * Put a zero at the end of the buffer, so it will be 
     * properly terminated 
     */
    put_user('\0', (char *)ioctl_param + i);
    break;
    
  case IOCTL_GET_NTH_BYTE:
    /* 
     * This ioctl is both input (ioctl_param) and 
     * output (the return value of this function) 
     */
    return Message[ioctl_param];
    break;
  }
  
  return SUCCESS;
}

/* Module Declarations */

/* 
 * This structure will hold the functions to be called
 * when a process does something to the device we
 * created. Since a pointer to this structure is kept in
 * the devices table, it can't be local to
 * init_module. NULL is for unimplemented functions. 
 */
static struct file_operations Fops = {
  .read = device_read,
  .write = device_write,
  .ioctl = device_ioctl,
  .open = device_open,
  .release = device_release,	/* a.k.a. close */
};

/* 
 * Initialize the module - Register the character device 
 */
static int __init mod_init(void)
{
  int ret_val;
  /* 
   * Register the character device (atleast try) 
   */
  ret_val = register_chrdev(MAJOR_NUM, "de2_lcd16207", &Fops);
  
  /* 
   * Negative values signify an error 
   */
  if (ret_val < 0) {
    printk(KERN_ALERT "%s failed with %d\n",
	   "Sorry, registering the character device ", ret_val);
    return ret_val;
  }

#ifdef DEBUG
  printk(KERN_INFO "Device %s registered\n", DEVICE_FILE_NAME);
#endif
/*  
  printk(KERN_INFO "%s The lcd16207 major device number is %d.\n",
	 "Registeration is a success", MAJOR_NUM);
  printk(KERN_INFO "If you want to talk to the device driver,\n");
  printk(KERN_INFO "you'll have to create a device file. \n");
  printk(KERN_INFO "We suggest you use:\n");
  printk(KERN_INFO "mknod %s c %d 0\n", DEVICE_FILE_NAME, MAJOR_NUM);
  printk(KERN_INFO "The device file name is important, because\n");
  printk(KERN_INFO "the ioctl program assumes that's the\n");
  printk(KERN_INFO "file you'll use.\n");
*/  
  mdelay(20);
  WriteNios(ADR_LCD_COMMAND,LCD_COM_RESET);
  mdelay(5);
  WriteNios(ADR_LCD_COMMAND,LCD_COM_RESET);
  udelay(200);
  WriteNios(ADR_LCD_COMMAND,LCD_COM_RESET);
  udelay(200);
  WriteNios(ADR_LCD_COMMAND,LCD_NUMROWS | LCD_INTERFACE | LCD_CMD_FUNC);
  udelay(50);
  WriteNios(ADR_LCD_COMMAND,LCD_CMD_ONOFF);
  udelay(50);
  WriteNios(ADR_LCD_COMMAND,LCD_CMD_CLEAR);
  mdelay(2);
  WriteNios(ADR_LCD_COMMAND,LCD_CMD_ONOFF | LCD_CMD_ENABLE_DISP | LCD_CMD_ENABLE_CURSOR | LCD_CMD_ENABLE_BLINK);
  udelay(50);
  //write "Hello! " to the display
  WriteNios(ADR_LCD_DATA,0x48);
  udelay(50);
  WriteNios(ADR_LCD_DATA,0x65);
  udelay(50);
  WriteNios(ADR_LCD_DATA,0x6C);
  udelay(50);
  WriteNios(ADR_LCD_DATA,0x6C);
  udelay(50);
  WriteNios(ADR_LCD_DATA,0x6F);
  udelay(50);
  WriteNios(ADR_LCD_DATA,0x21);
  udelay(50);
  WriteNios(ADR_LCD_DATA,0x20);
  udelay(50);
  
  return 0;
}

/* 
 * Cleanup - unregister the appropriate file from /proc 
 */
static __exit mod_exit(void)
{
  int ret;
  
  /* 
   * Unregister the device 
   */
  ret = unregister_chrdev(MAJOR_NUM, "de2_lcd16207");
  
  /* 
   * If there's an error, report it 
   */
   if (ret < 0)
      printk(KERN_ALERT "Error: unregister_chrdev: %d\n", ret);

}

static int WriteNios(unsigned long addr, unsigned long value)
{
  int ret = 0;
  unsigned long data;
  unsigned long *p = (unsigned long *)addr;
  data = (unsigned long)(value);
  ret = put_user(data, p);
  return ret;
}

static int ReadNios(unsigned long addr, unsigned long * pValue)
{
  int ret = 0;
  unsigned long *p = (unsigned long *)addr;
  if (get_user(*pValue, p))
    return -EFAULT;
  return ret;
}

module_init( mod_init );
module_exit( mod_exit );

#define author "The kernel programming guide, NIOS wiki users and mamba"
#define description "A driver for lcd16207 device of the DE2 board and the lcd16207 core of altera."
MODULE_AUTHOR(author);
MODULE_DESCRIPTION(description);
MODULE_SUPPORTED_DEVICE(DEVICE_NAME);
MODULE_LICENSE("GPL");