mt7628 gpio模拟spi驱动si32171

si32171 做从，mt7628做主，si32171的spi时序要求：When using a hardware SPI, the user should configure the port for CPOL=1(SCLK/SPICLK is high when not clocking) and CPHA=1 (SDI/MOSI data change onSCLK/SPICLK falling and SDO/MISO is latched on SCLK /SPICLK rising). 当不需要时钟时，sclk电平为高。当主机发送数据时，在时钟的下降沿开始改变数据，在时钟的上升沿锁存数据，即si32171接收数据。当si32171发送数据时，在sclk低电平时数据可以变化，在sclk的上升沿把数据发送出去。

直接上源码：

#include <linux/mm.h>
#include <linux/miscdevice.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/mman.h>
#include <linux/random.h>
#include <linux/init.h>
#include <linux/raw.h>
#include <linux/tty.h>
#include <linux/capability.h>
#include <linux/ptrace.h>
#include <linux/device.h>
#include <linux/highmem.h>
#include <linux/crash_dump.h>
#include <linux/backing-dev.h>
#include <linux/bootmem.h>
#include <linux/splice.h>
#include <linux/pfn.h>
#include <linux/export.h>
#include <linux/io.h>
#include <linux/aio.h>
#include <linux/kernel.h>
#include <linux/module.h>

#include <asm/uaccess.h>
#define _DBUG_
#undef _DBUG_

#define DEVICE_NAME     "spidev"  //加载模式后，执行”cat /proc/devices”命令看到的设备名称 
#define SPI_MAJOR       0       //主设备号
//#define delays	300 
#define delays 100
#define delay 100
#define LA_GAO 1
#define LA_DI 0
volatile unsigned long *GPIO_CTRL_1;
volatile unsigned long *GPIO_CTRL_0;  //输出方向控制
volatile unsigned long *GPIO_POL_0;		//数据是否翻转
volatile unsigned long *GPIO_DATA_0;  // 什么数据
volatile unsigned long *GPIO_DATA_1;
volatile unsigned long *GPIOMODE;
volatile unsigned long *AGPIO_CFG;
#define _BUF_
#undef _BUF_

#ifdef _BUF_
char *buf=NULL;
#define COUNT 20
#endif

static struct class *spi_drv_class;
/*
	cs: gpio14
	clk: gpio15
	miso: gpio45
	mosi: gpio17

<span style="white-space:pre">	</span>slic reset:gpio 5
*/

static int spi_drv_open(struct inode *inode, struct file *file)
{
	printk("%s:Hello spi\n", __FUNCTION__);	// printk用于驱动中添加打印，用法和应用程序中的printf一样
	return 0;
}

static char readByte(void)
{
    	char ch = 0;
    	int i = 7;
	char mask[] = {0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80};
	*GPIO_DATA_0&=~(1<<14);// 拉低片选
	ndelay(delays);

	for(i=7;i>=0;i--)

	{
		*GPIO_DATA_0 &=~(1<<15);// clk 拉低
	
		if((*GPIO_DATA_1>>13)&0x1)// 读第16位的数据
			ch|=mask[i];
		else
			ch&=~mask[i];		
	
		ndelay(delays);
	
		*GPIO_DATA_0|=(1<<15);// clk 拉高
		ndelay(delays);//延时delaysns
		
	}
	*GPIO_DATA_0|=(1<<14);// 拉高取消片选
	#ifdef _DBUG_
        printk("spi read 0x%02x\n",ch);
	#endif
    return ch;
}


static ssize_t spi_drv_read(struct file *file, char __user *buff, size_t size, loff_t *ppos)
{
	#ifndef _BUF_
    char *buf=NULL;
	 buf=(char *)kmalloc(size, GFP_KERNEL);
	#else
	 memset(buf,0x0,COUNT);
 	#endif
    int i=0;
    char j=0;
   
   
    for(i=0;i<size;i++)
    {
	buf[i]=readByte();

    }

    j=copy_to_user((char *)buff,buf,size);
    if(j)
		printk("copy error\n");
	#ifndef _BUF_
    kfree(buf);
   #endif
    return size;
}

static void writeByte(const char c)
{
   int i = 7;
	char mask[] = {0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80};
	*GPIO_DATA_0&=~(1<<14);// 拉低片选
	ndelay(delays);

	for(i=7;i>=0;i--)
	{
		*GPIO_DATA_0&=~(1<<15);// clk 拉低
		if(c&mask[i])
		{
			*GPIO_DATA_0|=(1<<17);// 往里面写入1
		}
		else
		{
			*GPIO_DATA_0&=~(1<<17);// 往里面写入0
		}	
		ndelay(delays);//延时delaysns

		*GPIO_DATA_0|=(1<<15);// clk 拉高
		ndelay(delays);//延时delaysns
	
	}
	*GPIO_DATA_0|=(1<<14);// 拉高取消片选
	
	 return ;
}

static ssize_t spi_drv_write(struct file *file, const char __user *ubuf, size_t count, loff_t *ppos)
{
//	printk("%s:Hello spi\n", __FUNCTION__);	// printk用于驱动中添加打印，用法和应用程序中的printf一样
    int i=0;
	#ifndef _BUF_
    char *buf=NULL;
    buf=(char *)kmalloc(count,GFP_KERNEL);
    #else
    memset(buf,0x0,COUNT);		
	#endif
    if(copy_from_user(buf,(char *)ubuf,count))
    {
        printk("no enough memory!\n");
        return -1;
    }
    for(i=0;i<count;i++)
    {
	#ifdef _DBUG_
        printk("spi write 0x%02X!\n",*buf);
	#endif
        writeByte(buf[i]);
        //buf++;
    }
	#ifndef _BUF_
    kfree(buf);
	#endif
    return count;
}

static long gpio_rst__drv_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        switch(cmd)
        {
                case LA_GAO:
                        *GPIO_DATA_0 |=(1<<5);
                        printk("%s: LA GAO\n", __FUNCTION__);
                        break;
                case LA_DI:
                        *GPIO_DATA_0 &=~(1<<5);
                        printk("%s:LA DI\n", __FUNCTION__);
                        break;
                default:
                        break;
        }
        return 0;
}

static struct file_operations spi_drv_fops = {
	.owner  	= THIS_MODULE,    /* 这是一个宏，推向编译模块时自动创建的__this_module变量 */
	.open   	= spi_drv_open,     
	.read	= spi_drv_read,	   
	.write	= spi_drv_write,	   
	.unlocked_ioctl = gpio_rst__drv_ioctl,

};

int major;

static int __init spi_drv_init(void)
{
	major = register_chrdev(SPI_MAJOR, DEVICE_NAME, &spi_drv_fops);
	if (major < 0)
	{
		printk(DEVICE_NAME " can't register major number\n");
		return major;
	}
	
	spi_drv_class = class_create(THIS_MODULE, "spi");
	device_create(spi_drv_class, NULL, MKDEV(major, 0), NULL, "spi");		// /dev/spi

	printk("%s:Hello spi\n", __FUNCTION__);	// printk用于驱动中添加打印，用法和应用程序中的printf一样

	AGPIO_CFG=(volatile unsigned long *)ioremap(0x1000003c,4);
	GPIOMODE=(volatile unsigned long *)ioremap(0x10000060,4);

	GPIO_CTRL_0=(volatile unsigned long *)ioremap(0x10000600,4);
	GPIO_CTRL_1=(volatile unsigned long *)ioremap(0x10000604,4);
	GPIO_DATA_0=(volatile unsigned long *)ioremap(0x10000620,4);
	GPIO_DATA_1=(volatile unsigned long *)ioremap(0x10000624,4);
		
	*AGPIO_CFG|=(1<<20)|(1<<19)|(1<<18)|(1<<17);//全部设置为1
	*GPIOMODE&=~(0x3<<2);
	*GPIOMODE&=~(0x3<<24);
	*GPIOMODE|=(1<<2)|(1<<24);// 设置GPIO 模式功能
   *GPIOMODE&=~(0x3<<20);// set gpio 5 rest
   *GPIOMODE|=(1<<20);// 
	
	*GPIO_CTRL_0|=(1<<14)|(1<<15)|(1<<17);// GPIO 14 15 17 为输出
        //*GPIO_CTRL_0&=~(1<<16);// GPIO 16 为输入 经过测试该引脚不行，换了gpio45
   *GPIO_CTRL_1&=~(1<<13);// 45
	*GPIO_DATA_0|=(1<<15);
   *GPIO_DATA_0|=(1<<14);
   *GPIO_CTRL_0|=(1<<5);// set gpio 5 output 
	#ifdef _BUF_
    buf=(char *)kmalloc(COUNT,GFP_KERNEL);
	#endif _BUF_
	
	return 0;
}



static void __exit spi_drv_exit(void)
{
	unregister_chrdev(major, "spi");		// 与入口函数的register_chrdev函数配对使用
	device_destroy(spi_drv_class, MKDEV(major, 0));	// 与入口函数的device_create函数配对使用
	class_destroy(spi_drv_class);	// 与入口函数的class_create函数配对使用
	iounmap(GPIOMODE);
	iounmap(AGPIO_CFG);
	iounmap(GPIO_CTRL_0);
	iounmap(GPIO_CTRL_1);
	iounmap(GPIO_DATA_1);
	iounmap(GPIO_DATA_0);
	printk("%s:Hello spi\n", __FUNCTION__);	// printk用于驱动中添加打印，用法和应用程序中的printf一样
	#ifdef _BUF_
	kfree(buf);
	#endif
}

module_init(spi_drv_init);
module_exit(spi_drv_exit);

MODULE_AUTHOR("http://www.spi.com");
MODULE_VERSION("0.1.0");
MODULE_DESCRIPTION("RT5350 FIRST Driver");
MODULE_LICENSE("GPL");

注意：在驱动中的write_byte(),read_byte()中不要调用printk函数，这样会严重影响正常时序，分配的内存用完一定要free掉，否则内存会造成内存

不足导致系统崩溃，一定要确保硬件是可行的，检查引脚是否输出正确。