lcd.c

用于Linux 2.4内核的LCD及键盘驱动

#ifndef __KERNEL__
#define __KERNEL__
#endif

#ifndef MODULE
#define MODULE
#endif

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/ioport.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/8xx_immap.h>

/*
* Header files for the charcater device 
*/
#include <linux/fs.h>
#include <linux/wrapper.h>

#include "lcd.h"

#define DEBUG

static volatile immap_t *immap;	/*define the struct immap_t pointer that represent memory map info */
volatile unsigned long virt_base;/*lcd virtual address space base*/
static int device_open_num = 0;	/*record numbers of lcd device opening by usr */
static int Major;		/*the lcd device major number */



/*********************************************************
***************LCD hard interface functions***************
**********************************************************/

/*
*Initialize the driver -Register the character device
*/

static int
lcd_init (void)
{

  int ret;
  init_mem ();
  /*
   *Register the character device -lcd
   */

  ret = register_chrdev (LCD_MAJOR, DEVICE_NAME, &lcd_ops);

  /* register lcd device faild */
  if (ret < 0)
    {

      iounmap ((void *) virt_base);
      printk ("Lcd init_module register failed 
          with %d\n major number\n", Major);
      return Major;
    }
  /*register successed */
  Major = LCD_MAJOR;
  printk ("Lcd register major number :%d successed\n", Major);

  /*
   *Lcd function initial
   */
  lcd_ctr_init ();

  writeb (LED_OFF, (LED_ADDR - LCD_BASE) + virt_base);/*turn off led */
  //writeb (LED_OFF, LED_ADDR); /*turn off led */
  return SUCCESS;
}


static int
init_mem (void)
{

  immap = (immap_t *) (mfspr (IMMR) & 0xffff0000);
  immap->im_memctl.memc_br7 = BR7_SET;
  immap->im_memctl.memc_or7 = OR7_SET;

#ifdef DEBUG
  printk ("br7 = 0x%08x\n", immap->im_memctl.memc_br7);
  printk ("or7 = 0x%08x\n", immap->im_memctl.memc_or7);
#endif

  /*memory map */
  virt_base = (unsigned long) ioremap (LCD_BASE, LCD_VIRT_LENGTH);

  return SUCCESS;

}

static void
lcd_ctr_init (void)
{

  mdelay (15);
  lcd_set (FUNCTION_SET);
  mdelay (4);
  lcd_set (DISPLAY_OFF);
  lcd_set (DISPLAY_ON);
  lcd_set (INPUT_MODE_SET);
  lcd_set (DISPLAY_CLEAR);

#ifdef DEBUG
  showch (0x48);
#endif


}

static void
lcd_set (unsigned char command)
{
  writeb (command, (LCD_DATA_ADDR-LCD_BASE)+virt_base); /*first output control command */
  udelay (10);
  writeb (WRITE_REG | ENABLE_OFF, (LCD_CTRREG_ADDR - LCD_BASE) + virt_base);
  udelay (1);
  writeb (WRITE_REG | ENABLE_ON, (LCD_CTRREG_ADDR - LCD_BASE) + virt_base);
  udelay (1);
  writeb (WRITE_REG | ENABLE_OFF, (LCD_CTRREG_ADDR - LCD_BASE) + virt_base);
  mdelay (40);			/*wait for command to ouput to lcd register */
#ifdef DEBUG
  printk ("Lcd port output data finished\n");
#endif
}

static void
showch (unsigned char ch)
{
  writeb (BIT_SWAP (ch), (LCD_DATA_ADDR - LCD_BASE) + virt_base);	/*first output data to port */
  udelay (10);
  writeb (WRITE_DATA | ENABLE_OFF, (LCD_CTRREG_ADDR - LCD_BASE) + virt_base);
  udelay (1);
  writeb (WRITE_DATA | ENABLE_ON, (LCD_CTRREG_ADDR - LCD_BASE) + virt_base);
  udelay (1);
  writeb (WRITE_DATA | ENABLE_OFF, (LCD_CTRREG_ADDR - LCD_BASE) + virt_base);
  mdelay (40);			/*wait for date to ouput to lcd ram */
}


/***************************************************
****Standard  driver operation functions************
****************************************************/

/*
*Called whenever a process attempt to open the lcd device
*/

static int
device_open (struct inode *inode, struct file *lcd_device_file)
{
  if (device_open_num)		/*ensure open lcd device exclusively */
    {
      return -EBUSY;		/*lcd device has been open by other process */
    }

  /*
   *Make sure that this module isn't removed while
   *the lcd is open by increasing the lcd usage count
   */
  if (check_region (LCD_BASE, LCD_VIRT_LENGTH))
    {
      printk ("%s memory already in use\n", DEVICE_NAME);
      return -EBUSY;
    }

  request_region (LCD_BASE, LCD_VIRT_LENGTH, DEVICE_NAME);

  device_open_num++;
  MOD_INC_USE_COUNT;
  lcd_set (DISPLAY_CLEAR);
  lcd_set (INPUT_MODE_SET);
#ifdef DEBUG
  printk (DEVICE_NAME " open successed \n");
#endif
  return SUCCESS;

}

/*
*Called whenever a process closes the lcd device
*/
static int
device_release (struct inode *inode, struct file *lcd_device_file)
{
  /*
   *Make sure that this module isn't removed while
   *the lcd is open by increasing the lcd usage count
   */
  device_open_num--;
  MOD_DEC_USE_COUNT;
  release_region (LCD_BASE, LCD_VIRT_LENGTH);
#ifdef DEBUG
  printk (DEVICE_NAME " closed successed \n");
#endif

  return SUCCESS;
}

/*
*The Lcd device driver write function
*/

static ssize_t
device_write (struct file *lcd_device_file, const char *buffer,	/*buffer for data outputed to lcd */
	      size_t length,	/*length of buffer */
	      loff_t * offset)	/*file pointer offset */
{
  unsigned char ch;
  int error;
  int i = 0;
  int line_count = 0;
  while (i < length)
    {
      if (line_count < 16)
	{
	  if (line_count == 8)
	    lcd_set (CHANGE_LINE);
	  if ((error = get_user (ch, buffer)) != 0)
	    {
	      return 0;
	    }
	  buffer++;
	  i++;
	  line_count++;
	  showch (ch);
	}
      else
	{
	  mdelay (2000);
	  line_count = 0;
	  lcd_set (DISPLAY_CLEAR);
	}
    }
  return length;
}


/***********************************
**** Linux Module functions*********
************************************/

#ifdef MODULE

/*
*Initialize the lcd device driver module
*/
int
init_module (void)
{
  return lcd_init ();
}

/*
*Cleanup the lcd device driver moudle
*/

void
cleanup_module ()
{
  int ret;
#ifdef DEBUG
  printk ("I realse myself from kernel\n");
#endif
  /*unmap memory */
  iounmap ((void *) virt_base);

  /* Unregister the device */
  ret = unregister_chrdev (Major, DEVICE_NAME);
  if (ret < 0)
    {
      printk ("unregister char_dev :error%d\n", ret);
    }

  lcd_set (DISPLAY_OFF);
  lcd_set (DISPLAY_CLEAR);
  writeb (LED_ON, (LED_ADDR - LCD_BASE) + virt_base);	/*turn on led */
}

#endif /*MODULE*/