i2c.c

飞利浦lpc2200实验箱关于i2c接口的驱动代码。代码非常详细有注释。

/****************************************Copyright (c)**************************************************
**                               Guangzou ZLG-MCU Development Co.,LTD.
**                                     graduate school
**                                 http://www.zlgmcu.com
**
**--------------File Info-------------------------------------------------------------------------------
** File name:           i2c.c
** Last modified Date:  2005-05-17
** Last Version:        1.0
** Descriptions:        This is a Kernel module for uClinux 2.4.x .
**                      This module let uClinux 2.4.x can use I2C. 
**------------------------------------------------------------------------------------------------------
** Created by:          Chenmingji
** Created date:        2005-05-17
** Version:             1.0
** Descriptions:        The original version
**
**------------------------------------------------------------------------------------------------------
** Modified by:
** Modified date:
** Version:
** Descriptions:
**

********************************************************************************************************/
#define IN_I2C
#include "config.h"

/********************************************************************************************************
              function announce
********************************************************************************************************/

#if 0
static loff_t i2c_llseek(struct file *filp, loff_t off, int whence);
#endif

static ssize_t i2c_write(struct file *filp, const char *buf, size_t count, loff_t *f_pos);
static ssize_t i2c_read(struct file *filp, char *buf, size_t count, loff_t *f_pos);
static int i2c_open(struct inode *inode, struct file *filp);
static int i2c_release(struct inode *inode, struct file *filp); 
static int i2c_ioctl(struct inode *inode, struct file *filp, unsigned int cmd,
                     unsigned long param);
static void i2c_irq_handle(int irq, void *dev_id, struct pt_regs *regs);
int  i2c_init(void);
void i2c_cleanup(void);

/********************************************************************************************************
              define announce
********************************************************************************************************/
#define MAJOR_NR major

module_init(i2c_init);
module_exit(i2c_cleanup);

MODULE_PARM(major, "i");

MODULE_LICENSE("Proprietary");
MODULE_DESCRIPTION("Guangzou ZLG-MCU Development Co.,LTD.\ngraduate school\nhttp://www.zlgmcu.com");
MODULE_SUPPORTED_DEVICE("uClinux2.4.x LPC2200 i2c");
MODULE_AUTHOR("chenmingji");

/*********************************************************************************************************
**                  "全局和静态变量在这里定义"         
**        global variables and static variables define here
********************************************************************************************************/
unsigned int        usage;          /* device using count */
struct semaphore    sem, irq_sem;   /* mutual exclusion semaphore     */

static int major = I2C_MAJOR_NR;
static u32 PinSel0Save;
static u8 *I2cBuf;
static size_t I2cNbyte;
static u8 I2cAddr;

/********************************************************************************************************/

static struct file_operations i2c_fops =        /* driver info  */
{
    owner:      THIS_MODULE,
#if 0
    llseek:     i2c_llseek,
#endif
    write:      i2c_write,
    read:       i2c_read,
    ioctl:      i2c_ioctl,
    open:       i2c_open,
    release:    i2c_release,
};


#if 0
/*********************************************************************************************************
** Function name: i2c_llseek
** Descriptions:  move read and write point
** Input: filp:   pointer of file
**        off:    ofset
**        whence: move mode
**                0: seek set
**                1: seek file' current point
**                2: seek file' end
** Output :      new point
** Created by:   Chenmingji
** Created Date: 2005-5-17
**-------------------------------------------------------------------------------------------------------
** Modified by:
** Modified Date: 
**------------------------------------------------------------------------------------------------------
********************************************************************************************************/
        static loff_t i2c_llseek(struct file *filp, loff_t off, int whence)
{
    return 0;
}
#endif

/*********************************************************************************************************
** Function name: i2c_read
** Descriptions:  read device
** Input: filp:   pointer of file
**        buf:    buf for save data
**        count:  size for read
**        f_pos:  *f_pos = read point
** Output : read size    
** Created by:   Chenmingji
** Created Date: 2005-5-17
**-------------------------------------------------------------------------------------------------------
** Modified by:
** Modified Date: 
**------------------------------------------------------------------------------------------------------
********************************************************************************************************/
        static ssize_t i2c_read(struct file *filp, char *buf, size_t count,
                           loff_t *f_pos)
{
    unsigned long flag;
    unsigned int num;
        
    if (!access_ok(VERIFY_WRITE, (void *)buf, _IOC_SIZE(cmd)))
    {
        return -EFAULT;
    }

    if (down_interruptible(&sem))
    {
        return -ERESTARTSYS;
    }

    num = (unsigned int)filp->private_data;

    local_irq_save(flag);
    outl(0x6C, I2CONCLR);
    outl(0x40, I2CONSET);                       /* 使能I2c */
    I2cAddr = num | 0x01;                       /* 存储发送地址 */
    I2cNbyte = count;                           /* 存储读字节数 */
    I2cBuf = (u8 *)buf;                         /* 存储读到的数据 */
    outl(0x24, I2CONSET);                       /* 设置为主机，并启动总线 */
    local_irq_restore(flag);

    if (down_interruptible(&irq_sem))
    {
        up(&sem);
        return -ERESTARTSYS;
    }
    up(&sem);
    return count - I2cNbyte;
}

/*********************************************************************************************************
** Function name: i2c_write
** Descriptions:  write device
** Input: filp:   pointer of file
**        buf:    buf to write data
**        count:  size for write
**        f_pos:  *f_pos = write point
** Output : write size    
** Created by:   Chenmingji
** Created Date: 2005-5-17
**-------------------------------------------------------------------------------------------------------
** Modified by:
** Modified Date: 
**------------------------------------------------------------------------------------------------------
********************************************************************************************************/
        static ssize_t i2c_write(struct file *filp, const char *buf, size_t count,
                            loff_t *f_pos)
{
    unsigned long flag;
    unsigned int num;
        
    if (!access_ok(VERIFY_READ, (void *)buf, count))
    {
          return -EFAULT;
    }

    num = (unsigned int)filp->private_data;

    if (down_interruptible(&sem))
    {
        return -ERESTARTSYS;
    }

    local_irq_save(flag);
    outl(0x6C, I2CONCLR);
    outl(0x40, I2CONSET);                               /* 使能I2c */
    I2cAddr = num & 0xfe;                               /* 存储发送地址 */
    I2cNbyte = count;                                   /* 存储写字节数 */
    I2cBuf = (u8 *)buf;                                 /* 存储写的数据的指针 */
    outl(0x24, I2CONSET);                               /* 设置为主机，并启动总线 */
    local_irq_restore(flag);

    if (down_interruptible(&irq_sem))
    {
        up(&sem);
        return -ERESTARTSYS;
    }
    up(&sem);
    return count - I2cNbyte;
}
                
/*********************************************************************************************************
** Function name: i2c_open
** Descriptions:  open device
** Input:inode:   information of device
**       filp:    pointer of file
** Output 0:      OK
**        other:  not OK
** Created by:    Chenmingji
** Created Date:  2005-5-17
**-------------------------------------------------------------------------------------------------------
** Modified by:
** Modified Date: 
**------------------------------------------------------------------------------------------------------
********************************************************************************************************/
        static int i2c_open(struct inode *inode, struct file *filp)
{
    unsigned long flag;
    unsigned int num;
    u32 temp;

    num = MINOR(inode->i_rdev);

    if (usage == 0)
    {
        request_irq(IRQ_I2C, i2c_irq_handle, SA_INTERRUPT, "my" DEVICE_NAME, NULL);
        local_irq_save(flag);
        temp = inl(PINSEL0);
        PinSel0Save =  temp & (0x0f << 4);
        temp &= ~(0xf << 4);
        temp |= (0x05 << 4);
        outl(temp, PINSEL0);

        outl(0x6C, I2CONCLR);                /* 清除控制寄存器 */