S3C2440 spi驱动简单测试（转）

来源：互联网发布：幼儿园淘宝节活动流程编辑：程序博客网时间：2024/05/29 03:55

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(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=%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); 
  
    return 0; 
} 
  
  
static int spi_release(struct inode *inode,struct file *filp) 
{ 
    //free irq 
    free_irq(IRQ_EINT1, NULL); 
  
    printk("<1>release/n"); 
    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=%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++; 
    } 
    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 <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(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%02X/n",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。

S3C2440 spi驱动简单测试 （转）

S3C2440 spi驱动简单测试（转）