linux-2.6.26下SPI1(3) 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 <linux/irq.h>

#include <linux/miscdevice.h>

#include <linux/delay.h>

#include <asm/irq.h>

#include <linux/interrupt.h>

#include <mach/regs-gpio.h>

#include <mach/hardware.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/init.h>

#include <linux/mm.h>

#include <linux/fs.h>

#include <linux/types.h>

#include <linux/delay.h>

#include <linux/moduleparam.h>

#include <linux/slab.h>

#include <linux/errno.h>

#include <linux/ioctl.h>

#include <linux/cdev.h>

#include <linux/string.h>

#include <linux/list.h>

#include <linux/pci.h>

#include <linux/gpio.h>

#include <asm/uaccess.h>

#include <asm/atomic.h>

#include <asm/unistd.h>

#include <linux/spinlock.h>

#include <asm/system.h>

#include <asm/uaccess.h>

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(structinode *,struct file *);

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

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

static ssize_t spi_read(struct file *filp,char *buf,size_tcount,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(structinode *inode,struct file *filp)

{

filp->private_data =&spiCdev;

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

*PCLK

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

/*control PCLK into spi block*/

*s3c2440_clkcon |=0x40000;

printk("s3c2440_clkcon=%08X\n",*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=%02X\n",*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=%02X\n",*spi_spcon1);

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

*spi_sppin1=(0<<2)|(0<<0);

printk("spi_sppin1=%02X\n",*spi_sppin1);

return0;

}

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

{

//free irq

free_irq(IRQ_EINT1, NULL);

printk("<1>release\n");

return0;

}

static void writeByte(constchar c)

{

intj = 0;

*spi_sptdat1 = c;

for(j=0;j<0xFF;j++);

while(!SPI_TXRX_READY)

for(j=0;j<0xFF;j++);

}

static char readByte(void)

{

intj = 0;

charch = 0;

*spi_sptdat1 = (char)loopChar;

for(j=0;j<0xFF;j++);

while(!SPI_TXRX_READY)

for(j=0;j<0xFF;j++);

ch=*spi_sprdat1;

returnch;

}

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

{

//int len=0;

charch;

printk("<1>spi read!\n");

ch=readByte();

copy_to_user(buf,&ch,1);

return1;

}

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

{

inti;

char*kbuf;

printk("<1>spi write!,count=%d\n",count);

kbuf=kmalloc(count,GFP_KERNEL);

if(copy_from_user(kbuf,buf,count))

{

printk("no enough memory!\n");

return-1;

}

for(i=0;i<count;i++)

{

writeByte(*kbuf);

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

kbuf++;

}

returncount;

}

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

{

return0;

}

static int __init spi_init(void)

{

intresult;

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)

returnresult;

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");

returnresult;

}

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 <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <sys/ioctl.h>

#include<sys/types.h>

#include<sys/stat.h>

#include<fcntl.h>

int main(intargc, char **argv)

{

intfd;

intcount=0;

charbuf[]={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%02X\n",buf[0]);

close(fd);

return0;

}

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。

 原文出处：S3C2440 spi驱动简单测试