S3C2440 spi驱动简单测试

这两天参考网上的资料，自己写了个SPI的驱动，并实际测试通过。

硬件平台：mini2440 用的是S3C2440 的SPI1（共有2个SPI模块）

操作系统：linux-2.6.32.2

测试方法：将SPI的MISO与MOSI管脚短路，这样读数据的时候第一个发出的dummy字节即为收到的字节。

下面是驱动的源代码(mini2440_spi.c)：

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

#include

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int loopChar=0x88;

module_param(loopChar,int,S_IRUGO);

static int spi_major = 55;

#define spi_name 'mini2440_spi'

struct cdev spiCdev;

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

static int spi_open(struct inode *,struct file *);

static int spi_release(struct inode *,struct file *);

static ssize_t spi_write(struct file *filp,const char *buf,size_t count,loff_t *f_ops);

static ssize_t spi_read(struct file *filp,char *buf,size_t count,loff_t *f_ops);

static ssize_t spi_ioctl(struct inode *inode,struct file *filp,unsigned int cmd,unsigned long data);

volatile int *spi_gpfcon=NULL;//GPF Part define

volatile int *spi_gpfdat=NULL;

volatile int *spi_gpfup=NULL;

volatile int *spi_gpgcon=NULL;//GPG Part define

volatile int *spi_gpgdat=NULL;

volatile int *spi_gpgup=NULL;

volatile int *s3c2440_clkcon;

volatile int *spi_spcon1;//SPI Part define

volatile int *spi_spsta1;

volatile int *spi_sppin1;

volatile int *spi_sppre1;

volatile int *spi_sptdat1;

volatile int *spi_sprdat1;

#define SPI_TXRX_READY      (((*spi_spsta1)&0x1) == 0x1)

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

static const struct file_operations spi_fops = 

{

    .owner=THIS_MODULE,

    .open=spi_open,

    .read=spi_read,

    .ioctl=spi_ioctl,

    .release=spi_release,

    .write=spi_write,

};

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

static int spi_open(struct inode *inode,struct file *filp)

{

    filp->private_data =&spiCdev;    

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

    *PCLK

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

    /*control PCLK into spi block*/

    *s3c2440_clkcon |=0x40000;

    printk('s3c2440_clkcon=%08Xn',*s3c2440_clkcon);

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

    *GPG PORTS

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

    /*config SCK1,MOSI1,MISO1 = 11*/

    *spi_gpgcon |=0x0000FC00;

    /*poll up MISO1 MOSI1,SCK1*/

    *spi_gpgup &=0xFF1F;

    *spi_gpgup |=0x0060;

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

    *GPF PORTS

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

    *spi_gpfcon &= 0xFCF3;

    *spi_gpfcon |= 0x0108;  

    *spi_gpfup &= 0xED;

    *spi_gpfdat |= 0x10;

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

    *SPI REGS

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

    //SPI Baud Rate Prescaler Register,Baud Rate=PCLK/2/(Prescaler value+1)

    *spi_sppre1=0x18;       //freq = 1M

    printk('spi_sppre1=%02Xn',*spi_sppre1);

    //polling,en-sck,master,low,format A,nomal = 0 | TAGD = 1

    *spi_spcon1=(0<<6)|(0<<5)|(1<<4)|(1<<3)|(0<<2)|(0<<1)|(0<<0);

    printk('spi_spcon1=%02Xn',*spi_spcon1);

    //Multi Master error detect disable,reserved,rech=*spi_sprdat0;lease

    *spi_sppin1=(0<<2)|(0<<0);

    printk('spi_sppin1=%02Xn',*spi_sppin1);

    return 0;

}

static int spi_release(struct inode *inode,struct file *filp)

{

    //free irq

    free_irq(IRQ_EINT1, NULL);

    printk('<1>releasen');

    return 0;

}

static void writeByte(const char c)

{

    int j = 0;

    *spi_sptdat1 = c;

    for(j=0;j<0xFF;j++);

    while(!SPI_TXRX_READY)

        for(j=0;j<0xFF;j++);

}

static char readByte(void)

{

    int j = 0;

    char ch = 0;

    *spi_sptdat1 = (char)loopChar;

    for(j=0;j<0xFF;j++);

    while(!SPI_TXRX_READY)

        for(j=0;j<0xFF;j++);

    ch=*spi_sprdat1;

    return ch;

}

static ssize_t spi_read(struct file *filp,char __user *buf,size_t count,loff_t *f_ops)

{

    //int len=0;

    char ch;

    printk('<1>spi read!n');

    ch=readByte();

    copy_to_user(buf,&ch,1);

    return 1;

}

static ssize_t spi_write(struct file *filp,const char __user *buf,size_t count,loff_t *f_ops)

{

    int i;

    char *kbuf;

    printk('<1>spi write!,count=%dn',count);

    kbuf=kmalloc(count,GFP_KERNEL);

    if(copy_from_user(kbuf,buf,count))

    {

        printk('no enough memory!n');

        return -1;

    }

    for(i=0;i    {

        writeByte(*kbuf);

        printk('write 0x%02X!n',*kbuf);

        kbuf++;

    }

    return count;

}

static ssize_t spi_ioctl(struct inode *inode,struct file *filp,unsigned int cmd,unsigned long data)

{

    return 0;

}

static int __init spi_init(void)

{

    int result;

    dev_t devno = MKDEV(spi_major, 0);

    /**/

    if (spi_major)

        result = register_chrdev_region(devno, 1, spi_name);

    else  /**/

    {

        result = alloc_chrdev_region(&devno, 0, 1, spi_name);

        spi_major = MAJOR(devno);

    }  

    if (result < 0)

        return result;

    cdev_init(&spiCdev, &spi_fops);

    spiCdev.owner = THIS_MODULE;

    spiCdev.ops = &spi_fops;

    if (cdev_add(&spiCdev, devno, 1))

        printk(KERN_NOTICE 'Error adding spi %d', 0);

    s3c2440_clkcon = (int *)ioremap(0x4C00000c,3);

    spi_gpgcon = (int *)ioremap (0x56000060,4);

    spi_gpgdat = (int *)ioremap (0x56000064,2);

    spi_gpgup = (int *)ioremap (0x56000068,2);

    spi_gpfcon = (int *)ioremap (0x56000050,2);

    spi_gpfdat = (int *)ioremap (0x56000054,1);

    spi_gpfup = (int *)ioremap (0x56000058,1);

    spi_spcon1 = (int *)ioremap(0x59000020,1);

    spi_spsta1 = (int *)ioremap(0x59000024,1);

    spi_sppin1 = (int *)ioremap(0x59000028,1);

    spi_sppre1 = (int *)ioremap(0x5900002c,1);

    spi_sptdat1 = (int *)ioremap(0x59000030,1);

    spi_sprdat1 = (int *)ioremap(0x59000034,1);

    printk('Init spi success!n');  

    return result;

}

static void __exit spi_exit(void)

{

    cdev_del(&spiCdev);

    unregister_chrdev_region(MKDEV(spi_major, 0), 1);

    printk('<1>spi_exit!n');

}

module_init(spi_init);

module_exit(spi_exit);

MODULE_LICENSE('GPL');

MODULE_AUTHOR('nkzc');

MODULE_DESCRIPTION('SPI driver for S3C2440');

几点需要注意的地方：

1.一开始在spi_exit()函数中使用了void unregister_chrdev(unsigned int major, const char *name)函数来注销设备，但再次insmod驱动的时候提示'Device or resource busy'，改为unregister_chrdev_region()后一切正常，说明即使只注册了一个设备，register_chrdev_region()和unregister_chrdev_region()也要配套使用。

2.定义spi_spcon1等寄存器变量时前面要加上volatile关键字，这样每次访问该变量时cpu会从实际内存中读取该值而不是使用寄存器中的值。尤其是spi_spsta1变量，它的最低位代表了spi发送接收是否ready，如果没有volatile，可能会在readByte()或writeByte()函数中导致死循环。

3.使用了module_param()宏向驱动传递参数，这里定义了一个int型的loopChar参数，加载模块时使用insmod mini2440_spi.ko loopChar=123 来设置loopChar的值。

测试程序：spi_test.c

#include

#include

#include

#include

#include

#include

#include

int main(int argc, char **argv)

{

    int fd;

    int count=0;

    char buf[]={0x11,0x22,0x33,0x44,0x55};

    fd = open('/dev/mini2440_spi', O_RDWR);

    if (fd < 0) {

        perror('open device spi');

        exit(1);

    }

    count=write(fd,buf,sizeof(buf)/sizeof(buf[0]));

    read(fd,buf,1);

    printf('read byte is: 0x%02Xn',buf[0]);

    close(fd);

    return 0;

}

很简单的一个程序，分别调用了open,write,read,close函数，可以观察输出结果，验证驱动程序是否正确，read的输出即为loopChar的值。

注意：open的时候要注意第二个参数flag，只有当flag为O_RDWR时，驱动中的相应的spi_read,spi_write函数才会被调用。