spi.txt

spi驱动基于linux2.6内核 s3c2410

工作需要做了s3c2410下用spi接口驱动74H595移位寄存器来控制８个LED。linux下字符型驱动为比较简单的驱动类型，作为入门很合适。硬件连接s3c2410---74H595:　GPB0--RCLK SPICLK0--SRCLK SPIMOSI0--SER　VDD--/SRCLR GND--/OE 
编程流程可以参考2410用户手册部分p482前两步，关键是选择SPI的工作方式这个要看你连的什么硬件。这里我们选择的是FormatA方式。
以下是源代码部分：

#includelinux/config.h>
#includelinux/module.h>
#includelinux/kernel.h>
#includelinux/init.h>
#includeasm/hardware.h>
#includeasm/delay.h>
#includeasm/uaccess.h>
//#undef DEBUG
#define DEBUG
#ifdef DBUGE
#define DPRINTK(x...)    printk("s3c2410-spi:" ## x)
#else
#define DPRINTK(x...)
#endif
#ifdef CONFIG_SMP
#define __SMP__
#endif
/*
GPE3    nSS0
GPE11    SPIMOSI0
GPE12    SPIMISO0
GPE13 SPICLK0
*/
#define LED_SCLK    GPIO_E13
#define LED_SDAT    GPIO_E12
#define LED_RCLK    GPIO_B0
#define DEVICE_NAME    "s3c2410-spi"
#define SPI_MINOR    1
static int SPI_MAJOR = 0;
static char SpiData = 0;
static ssize_t s3c2410_spi_write(struct file* file,const char* buffer,size_t count,loff_t* ppos)
{
    copy_from_user(&SpiData,buffer,sizeof(SpiData));
    DPRINTK("write: SPI=0x%x,count = %d\n",SpiData,count);
  
    if((SPSTA0 & 0x01) == 0x01) //data Tx/Rx ready
    {
        SPTDAT0 = SpiData;
    }
    
    clr_gpio_bit(GPIO_B0);
    udelay(10);
    set_gpio_bit(GPIO_B0);
    
    return 0;    
}
static int s3c2410_spi_open(struct inode* inode,struct file* filp)
{
    DPRINTK(DEVICE_NAME "open \n");
    MOD_INC_USE_COUNT;
    
   set_gpio_ctrl(GPIO_MODE_nSS|GPIO_PULLUP_DIS|GPIO_E3);         //nSS    no-pullup 
   set_gpio_ctrl(GPIO_MODE_SPICLK|GPIO_PULLUP_DIS|GPIO_E13);     // CLK0     no-pullup 
       set_gpio_ctrl(GPIO_MODE_SPIMOSI|GPIO_PULLUP_EN|GPIO_E12);   //SPIMOSI    pullup 
       set_gpio_ctrl(GPIO_MODE_SPIMISO|GPIO_PULLUP_EN|GPIO_E13);         // SPIMISO     pullup 
     
    SPPRE0 = 0x00; //set baud rate prescaler register; Baud rate = PCLK/2/(Prescaler value + 1)
    SPCON0    = (06)|(05)|(14)|(13)|(12)|(01)|(00);
    //polling,en_sck,master,low,format A,normal
    SPPIN0 = (02)|(11)|(00);
    //Multi Master error detect disable, reserved release
    
    return 0; 
}
static int s3c2410_spi_release(struct inode* inode,struct file* filp)
{
    DPRINTK(DEVICE_NAME" release \n");
    MOD_DEC_USE_COUNT;
    
    return 0;
}
static struct file_operations s3c2410_spi_fops ={
    owner:         THIS_MODULE,
    open:         s3c2410_spi_open,
    write:        s3c2410_spi_write,
    release:    s3c2410_spi_release,
};
#ifdef CONFIG_DEVFS_FS
static devfs_handle_t devfs_spi_dir,devfs_spi_raw;
#endif
static int __init s3c2410_spi_init(void)
{    
    int ret;
    
    
    ret = register_chrdev(SPI_MAJOR,DEVICE_NAME,&s3c2410_spi_fops);
    if(ret  0)
    {
        printk(DEVICE_NAME "can't get major number\n");
        return ret;
    }
    
    SPI_MAJOR = ret;
    
    #ifdef CONFIG_DEVFS_FS
    devfs_spi_dir = devfs_mk_dir(NULL,"spi",NULL);
    devfs_spi_raw = devfs_register(devfs_spi_dir,"0",DEVFS_FL_DEFAULT,
            SPI_MAJOR,SPI_MINOR,S_IFCHR|S_IRUSR|S_IWUSR,&s3c2410_spi_fops,NULL);
    #endif
    DPRINTK(DEVICE_NAME "initialized\n");
    
    return 0;
}
static void __exit s3c2410_spi_exit(void)
{
    #ifdef CONFIG_DEVFS_FS
        devfs_unregister(devfs_spi_raw);
        devfs_unregister(devfs_spi_dir);
    #endif
        
        unregister_chrdev(SPI_MAJOR,DEVICE_NAME);
}
module_init(s3c2410_spi_init);
module_exit(s3c2410_spi_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("uniquepeng");
MODULE_DESCRIPTION("spi driver for s3c2410");