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一、SPI介绍
串行外设接口 (Serial Peripheral interface) 简称 SPI，是一种高速的，全双工，同步的通信总线，并 且在芯片的管脚上只占用四根线，节约了芯片的管脚。
而W25Q64是常见的串行闪存器件，W25Q64将8M字节的容量分为128个块，每个块大小为64K字节，每个块又分为16个扇区，每个扇区4K个字节。W25Q64的最小擦除单位为一个扇区，也就是每次必须擦除4K个字节。所以，这需要给W25Q64开辟一个至少4K的缓存区，这样必须要求芯片有4K以上的SRAM才能有很好的操作。
W25Q64的擦写周期多达10W次，可将数据保存达20年之久，支持2.7~3.6V的电压，支持标准的SPI，还支持双输出/四输出的SPI，最大SPI时钟可达80Mhz。
二、spi 基本知识
spi 总线都可以挂载多个设备，spi 支持标准的一主多从，全双工半双工通信等。
其中四根控制线 包括：
• SCK：时钟线，数据收发同步
• MOSI：数据线，主设备数据发送、从设备数据接收
• MISO：数据线，从设备数据发送，主设备数据接收
• NSS：片选信号线
i2c 通过 i2c 设备地址选择通信设备，而 spi 通过片选引脚选中要通信的设备。
spi 接口支持有多个片选引脚，连接多个 SPI 从设备，当然也可以使用外部 GPIO 扩展 SPI 设备的 数量，这样一个 spi 接口可连接的设备数由片选引脚树决定。
• 如果使用 spi 接口提供的片选引脚，spi 总线驱动会处理好什么时候选 spi 设备。
• 如果使用外部 GPIO 作为片选引脚需要我们在 spi 设备驱动中设置什么时候选中 spi。
(或者 在配置 SPI 时指定使用的片选引脚)。
通常情况下无特殊要求我们使用 spi 接口提供的片选引脚。
三、SPI时序
• 起始信号：NSS 信号线由高变低
• 停止信号：NSS 信号由低变高
• 数据传输：在 SCK 的每个时钟周期 MOSI 和 MISO 同时传输一位数据，高/低位传输没有硬 性规定
-- 传输单位：8 位或 16 位
-- 单位数量：允许无限长的数据传输
四、硬件原理分析
ATK-DLRK3568的外设IO有引出SPI1。
对应W25Q64接线如下：
|----------|-----------------------|
| W25Q64引脚 | ATK-DLRK3568 |
| 1-CS | GPIO3_A1 SPI1_CS0_M1 |
| 2-DO | GPIO3_C2 SPI1_MISO_M1 |
| 3-WP | 3.3V |
| 4-GND | GND |
| 5-DI | GPIO3_C1 SPI1_MOSI_M1 |
| 6-CLK | GPIO3_C3 SPI1_CLK_M1 |
| 7-HOLD | NC |
| 8-VCC | 3.3V |
使用杜邦线链接，确保接线正常。
五、创建设备节点
1、设备树节点
修改/home/alientek/rk3568_linux_sdk/kernel/arch/arm64/boot/dts/rockchip/目录下的rk3568-atk-evb1-ddr4-v10.dtsi文件，在文件末添加代码，在spi1设备树下添加w25q64节点。
&spi1 {
status = "okay";
pinctrl-names = "default", "high_speed";
pinctrl-0 = <&spi1m1_cs0 &spi1m1_pins>;
pinctrl-1 = <&spi1m1_cs0 &spi1m1_pins_hs>;
// 向 spi1 节点追加 w25q64 设备节点
w25q64: w25q64@0 {
compatible = "yifeng,w25q64";
reg = <0>; // 设置 reg 属性为 0, 表示 spi 连接到 spi1 的通道 0
spi-max-frequency = <24000000>; // 设置 SPI 传输的最大频率
wp-gpio = <&gpio3 RK_PA1 GPIO_ACTIVE_HIGH>;
pinctrl-0 = <&w25q64_wp>; /*<&w25q64_cs>; */
};
};
2、创建设备的 pinctrl 节点
修改/home/alientek/rk3568_linux_sdk/kernel/arch/arm64/boot/dts/rockchip/目录下的rk3568-pinctrl.dtsi文件，在最后面增加节点
w25q64 {
/omit-if-no-ref/
w25q64_wp: w25q64-wp {
rockchip,pins = <3 RK_PA1 RK_FUNC_GPIO &pcfg_pull_up>;
};
};
设备树修改完成以后在 SDK 顶层目录输入如下命令重新编译一下内核：
# 指定 SDK 的板级配置文件
./build.sh lunch
# 编译内核
./build.sh kernel
编译完成以后得到 boot.img, boot.img 就是编译出来的内核+设备树打包在一起的文件
只需要重新烧写boot.img。
烧写完成以后启动开发板。Linux 启动成功以后进入到/proc/device-tree/目录中查看是否有节点
六、编写驱动
1、spi_drv.c
#include <linux/module.h>//模块加载卸载函数
#include <linux/kernel.h>//内核头文件
#include <linux/types.h>//数据类型定义
#include <linux/fs.h>//file_operations结构体
#include <linux/device.h>//class_create等函数
#include <linux/ioctl.h>
#include <linux/kernel.h>/*包含printk等操作函数*/
#include <linux/of.h>/*设备树操作相关的函数*/
#include <linux/gpio.h>/*gpio接口函数*/
#include <linux/of_gpio.h>
#include <linux/platform_device.h>/*platform device*/
#include <linux/spi/spi.h> /*spi相关api*/
#include <linux/delay.h> /*内核延时函数*/
#include <linux/slab.h> /*kmalloc、kfree函数*/
#include <linux/cdev.h>/*cdev_init cdev_add等函数*/
#include <asm/uaccess.h>/*__copy_from_user 接口函数*/
#include <linux/moduleparam.h>
#include <linux/iio/iio.h>
#include <linux/iio/machine.h>
#include <linux/iio/driver.h>
#include <linux/iio/consumer.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/ide.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/gpio.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/of_gpio.h>
#include <linux/semaphore.h>
#include <linux/timer.h>
#include <linux/irq.h>
#include <linux/wait.h>
#include <linux/poll.h>
#include <linux/fs.h>
#include <linux/fcntl.h>
#include <linux/platform_device.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#define DEVICE_NAME "spi"
#define W25Qxx_PAGE_SIZE 256 /*页 大小256字节*/
#define W25QXX_SECTOR_SIZE 4096 /*扇区 大小4096*/
/*W25Qxx 指令*/
#define W25X_WriteEnable 0x06
#define W25X_WriteDisable 0x04
#define W25X_ReadStatusReg 0x05
#define W25X_WriteStatusReg 0x01
#define W25X_ReadData 0x03
#define W25X_FastReadData 0x0B
#define W25X_FastReadDual 0x3B
#define W25X_PageProgram 0x02
#define W25X_BlockErase 0xD8
#define W25X_SectorErase 0x20
#define W25X_ChipErase 0xC7
#define W25X_PowerDown 0xB9
#define W25X_ReleasePowerDown 0xAB
#define W25X_DeviceID 0xAB
#define W25X_ManufactDeviceID 0x90
#define W25X_JedecDeviceID 0x9F
typedef struct
{
void *tx_buf;
void *rx_buf;
unsigned char cmd; //w25q64指令
unsigned int address; //写入或者读取的地址
unsigned int tx_len; //需要写入的字节数
unsigned int rx_len; //需要读取的字节数
}w25qxx_data_def;
typedef struct
{
struct device_node *node;//设备树节点
struct cdev cdev; //定义一个cdev结构体
struct class *class; //创建一个w25q64类
struct device *device; //创建一个w25q64设备 该设备是需要挂在w25q64类下面的
int major; //主设备号
dev_t dev_id;
struct spi_device *spi; /*spi设备*/
int cspin; /*片选脚*/
int wppin;
struct mutex lock;
w25qxx_data_def data;
}w25qxx_typdef;
static w25qxx_typdef w25qxx_dev;//定义一个w25q64设备
/*函数声明*/
static int w25qxx_read_bytes(w25qxx_typdef *w25q64,unsigned int address,unsigned char* buf,int count);
static int w25q64_spi_read_write(w25qxx_typdef *w25q64)
{
struct spi_device *spi = w25q64->spi;
struct spi_transfer xfer[2];
struct spi_message msg;
int ret = 0;
unsigned char *buf,*readbuf;
memset(&xfer, 0, sizeof(xfer));/*必须清0 否则无法spi_sync函数无法发送数据*/
xfer[0].tx_buf = w25q64->data.tx_buf;
xfer[0].len = w25q64->data.tx_len;
buf = (unsigned char *)(w25q64->data.tx_buf);
xfer[1].rx_buf = w25q64->data.rx_buf;
xfer[1].len = w25q64->data.rx_len;
spi_message_init(&msg);
spi_message_add_tail(&xfer[0], &msg);
if(w25q64->data.rx_len)
{
spi_message_add_tail(&xfer[1], &msg);
}
ret = spi_sync(spi, &msg);
if(ret != 0)
{
printk("spi_sync failed %d\n", ret);
}
readbuf = (unsigned char *)(w25q64->data.rx_buf);
return ret;
}
static void spi_wp_enable(void)
{
gpio_set_value(w25qxx_dev.wppin, 1);
}
static void spi_wp_disable(void)
{
gpio_set_value(w25qxx_dev.wppin, 0);
}
static void spi_cs_enable(void)
{
//gpio_set_value(w25qxx_dev.cspin, 0); /* cs = 0 */
}
static void spi_cs_disable(void)
{
//gpio_set_value(w25qxx_dev.cspin, 1); /* cs = 1 */
}
static void spi_write_enable(void)
{
int ret;
unsigned char tx_buf[1];
spi_cs_enable();
tx_buf[0] = W25X_WriteEnable;/*写使能指令*/
w25qxx_dev.data.tx_buf= tx_buf;
w25qxx_dev.data.tx_len = 1;
w25qxx_dev.data.rx_len = 0;
ret = w25q64_spi_read_write(&w25qxx_dev);
spi_cs_disable();
}
static void spi_write_disable(void)
{
int ret;
unsigned char tx_buf[1];
spi_cs_enable();
tx_buf[0] = W25X_WriteDisable;/*写失能指令*/
w25qxx_dev.data.tx_buf= tx_buf;
w25qxx_dev.data.tx_len = 1;
w25qxx_dev.data.rx_len = 0;
ret = w25q64_spi_read_write(&w25qxx_dev);
spi_cs_disable();
}
static int w25qxx_get_sr(w25qxx_typdef *w25q64)
{
int ret = -EINVAL;
unsigned char tx_buf[1];
unsigned char rx_buf[1];
spi_cs_enable();
tx_buf[0] = W25X_ReadStatusReg;
w25q64->data.tx_buf= tx_buf;
w25q64->data.tx_len = 1;
w25q64->data.rx_buf = rx_buf;
w25q64->data.rx_len = 1;
ret = w25q64_spi_read_write(w25q64);
spi_cs_disable();
if(ret < 0)
{
printk("w25qxx_get_sr failed \n");
return ret;
}
return rx_buf[0];
}
static int w25qxx_get_id(w25qxx_typdef *w25q64)
{
int ret = -EINVAL;
unsigned char tx_buf[4];
unsigned char rx_buf[5];
spi_cs_enable();
tx_buf[0] = W25X_ManufactDeviceID;/*读取ID指令*/
tx_buf[1] = 0x0;
tx_buf[2] = 0x0;
tx_buf[3] = 0x0;
w25q64->data.tx_buf= tx_buf;
w25q64->data.tx_len = 4;
w25q64->data.rx_buf = rx_buf;
w25q64->data.rx_len = 2;
ret = w25q64_spi_read_write(w25q64);
spi_cs_disable();
if(ret != 0)
{
printk("w25qxx_get_id failed %d\n",ret);
return ret;
}
printk("rx_buf 0x%x 0x%x 0x%x 0x%x\n\r",rx_buf[0], rx_buf[1], rx_buf[2], rx_buf[3]);
return (rx_buf[0] << 8 | rx_buf[1]);
}
static void w25qxx_Reset(w25qxx_typdef *w25q64)
{
int ret = -EINVAL;
unsigned char tx_buf[4];//
unsigned char rx_buf[5];//
spi_wp_disable();
spi_cs_enable();
udelay(2);
tx_buf[0] = 0x66;/*读取ID指令*/
tx_buf[1] = 0x99;
w25q64->data.tx_buf= tx_buf;
w25q64->data.tx_len = 2;
w25q64->data.rx_buf = rx_buf;
w25q64->data.rx_len = 0;
ret = w25q64_spi_read_write(w25q64);
spi_cs_disable();
spi_wp_enable();
udelay(2);
if(ret < 0)
{
printk("w25qxx_get_id failed %d\n",ret);
}
else
{
printk("w25qxx_ Init Success %d\n",ret);
}
}
static int w25qxx_wait_idle(void)
{
int ret = -EINVAL;
do {
ret = w25qxx_get_sr(&w25qxx_dev);
if(ret < 0 )
{
return ret;/*通信错误*/
}
else
{
if(!(ret & 0x01))
{
return 0;/*w25q64空闲*/
}
}
/* REVISIT: at HZ=100, this is sloooow */
msleep(10);
} while(1);
return 1;
}
static int w25qxx_erase_sector(w25qxx_typdef *w25q64,unsigned int address)
{
int ret = -EINVAL;
unsigned char tx_buf[4];//
spi_write_enable();/*写保护关闭*/
spi_cs_enable();
tx_buf[0] = W25X_SectorErase;/*扇区擦除指令*/
tx_buf[1] = (unsigned char)((address>>16) & 0xFF);
tx_buf[2] = (unsigned char)((address>>8) & 0xFF);
tx_buf[3] = (unsigned char)(address & 0xFF);
w25q64->data.tx_buf= tx_buf;
w25q64->data.tx_len = 4;
w25q64->data.rx_len = 0;
ret = w25q64_spi_read_write(w25q64);
spi_cs_disable();
if(ret != 0)
{
printk("erase sector@%d failed %d\n",address,ret);
return ret;
}
ret = w25qxx_wait_idle();/*等待flash内部操作完成*/
spi_write_disable();/*写保护打开*/
return ret;
}
static int w25qxx_erase_chip(w25qxx_typdef *w25q64)
{
int ret = -EINVAL;
unsigned char tx_buf[1];//
spi_write_enable();/*写保护关闭*/
spi_cs_enable();
tx_buf[0] = W25X_ChipErase;/*扇区擦除指令*/
w25q64->data.tx_buf= tx_buf;
w25q64->data.tx_len = 1;
w25q64->data.rx_len = 0;
ret = w25q64_spi_read_write(w25q64);
spi_cs_disable();
if(ret != 0)
{
printk("erase chip failed %d\n", ret);
return ret;
}
ret = w25qxx_wait_idle();/*等待flash内部操作完成*/
spi_write_disable();/*写保护打开*/
return ret;
}
static int w25qxx_need_erase(unsigned char*old,unsigned char*new,int count)
{
int i;
unsigned char p;
for ( i = 0; i < count; i++)
{
p = *old++;
p = ~p;
if((p &(*new++))!=0)
{
return 1;
}
}
return 0;
}
static int w25qxx_read_bytes(w25qxx_typdef *w25q64,unsigned int address,unsigned char* buf,int count)
{
int ret = -EINVAL;
unsigned char tx_buf[4];//
spi_cs_enable();
tx_buf[0] = W25X_ReadData;/*读取数据指令*/
tx_buf[1] = (unsigned char)((address>>16) & 0xFF);
tx_buf[2] = (unsigned char)((address>>8) & 0xFF);
tx_buf[3] = (unsigned char)(address & 0xFF);
w25q64->data.tx_buf= tx_buf;
w25q64->data.tx_len = 4;
w25q64->data.rx_buf = buf;
w25q64->data.rx_len = count;
ret = w25q64_spi_read_write(w25q64);
spi_cs_disable();
if(ret != 0)
{
printk("read@%d ,%d bytes failed %d\n",address,count,ret);
return ret;
}
return ret;
}
static int w25qxx_write_page(w25qxx_typdef *w25q64,unsigned int address,unsigned char* buf,int count)
{
int ret = -EINVAL;
unsigned char *tx_buf;/*数据缓冲区*/
tx_buf = (unsigned char*)kzalloc(count+4,GFP_KERNEL);
if(!tx_buf)
return -ENOMEM;
spi_write_enable();/*写保护关闭*/
spi_cs_enable();
tx_buf[0] = W25X_PageProgram;/*页写指令*/
tx_buf[1] = (unsigned char)((address>>16) & 0xFF);
tx_buf[2] = (unsigned char)((address>>8) & 0xFF);
tx_buf[3] = (unsigned char)(address & 0xFF);
memcpy(&tx_buf[4],buf,count);
w25q64->data.tx_buf= tx_buf;
w25q64->data.tx_len = count+4;
w25q64->data.rx_len = 0;/*不需要读*/
//printk("tx_data:%d-%d-%d-%d,count=%d\n",tx_buf[4],tx_buf[5],tx_buf[6],tx_buf[7],w25q64->data.tx_len);
ret = w25q64_spi_read_write(w25q64);
spi_cs_disable();
if(ret != 0)
{
printk("write page@%d ,%d bytes failed %d\n",address,count,ret);
kfree(tx_buf);
spi_write_disable();/*写保护打开*/
return ret;
}
ret = w25qxx_wait_idle();
kfree(tx_buf);
spi_write_disable();/*写保护打开*/
return ret;
}
static int w25qxx_write_pages(w25qxx_typdef *w25q64,unsigned int address,unsigned char* buf,int count)
{
int ret = -EINVAL;
unsigned int remain_of_page,need_to_write;
unsigned int sector_first_address,sector_offset;
unsigned char *write_buf;/*数据缓冲区*/
write_buf = (unsigned char*)kzalloc(4096,GFP_KERNEL);
if(!write_buf)
return -ENOMEM;
/*获取指定地址所在扇区的扇区首地址*/
sector_first_address = address & (~(W25Qxx_PAGE_SIZE-1)) ;
/*获取指定地址在所在扇区内的偏移量*/
sector_offset = address % 4096;
ret = w25qxx_read_bytes(w25q64,sector_first_address,write_buf,4096);//读出整个扇区
if(ret < 0 )
{
return ret;
}
/*判断是否需要擦除*/
if(w25qxx_need_erase(&write_buf[sector_offset],buf,count))
{
printk("erase\n");
w25qxx_erase_sector(w25q64,sector_first_address);
}
kfree(write_buf);
remain_of_page = W25Qxx_PAGE_SIZE - address%W25Qxx_PAGE_SIZE;//获取本页还剩多少个字节空间可写入
need_to_write = remain_of_page;/*下一次最多可写remain_of_page个字节*/
printk("sector_first_address=%d,sector_offset=%d\n",sector_first_address,sector_offset);
printk("address=%d,count=%d\n",address,count);
if(count <= need_to_write)
{
/*需要写入的字节数少于剩余空间 直接写入实际字节数*/
ret = w25qxx_write_page(w25q64,address,buf,count);
return ret;
}
else
{
do
{
printk("address=%d\n,need_to_write=%d\n",address,need_to_write);
ret = w25qxx_write_page(w25q64,address,buf,need_to_write);
if(ret !=0)
{
return ret;
}
if(need_to_write == count)
{
break;
}
else
{
buf+=need_to_write;
address+=need_to_write;
count-=need_to_write;
if(count > W25Qxx_PAGE_SIZE)
{
need_to_write = W25Qxx_PAGE_SIZE;
}
else
{
need_to_write = count;
}
}
} while (1);
}
return ret;
}
static int w25qxx_write_more_bytes(w25qxx_typdef *w25q64,unsigned int address,unsigned char* buf,int count)
{
int ret = -EINVAL;
unsigned int num_of_sector,remain_of_sector,sector_offset;
unsigned int need_to_write;//sector_first_address
unsigned char *write_buf;/*数据缓冲区*/
write_buf = (unsigned char*)kzalloc(4096,GFP_KERNEL);
if(!write_buf)
return -ENOMEM;
num_of_sector = address / W25QXX_SECTOR_SIZE;
sector_offset = address % W25QXX_SECTOR_SIZE;
remain_of_sector = W25QXX_SECTOR_SIZE - address % W25QXX_SECTOR_SIZE;/*当前地址所在扇区 还剩下多少空间*/
need_to_write = remain_of_sector;
if(count <= need_to_write)
{
ret = w25qxx_write_pages(w25q64,address,buf,count);
return ret;
}
else
{
do
{
ret = w25qxx_write_pages(w25q64,address,buf,need_to_write);
if(ret !=0)
{
return ret;
}
if(need_to_write == count)
{
break;
}
else
{
buf+=need_to_write;
address+=need_to_write;
count-=need_to_write;
if(count > W25QXX_SECTOR_SIZE)
{
need_to_write = W25QXX_SECTOR_SIZE;
}
else
{
need_to_write = count;
}
}
} while (1);
}
return ret;
}
static int w25qxx_open(struct inode *inode, struct file *filp)
{
filp->private_data = &w25qxx_dev;
return 0;
}
static int w25qxx_release(struct inode* inode ,struct file *filp)
{
// w25qxx_typdef *dev = (w25qxx_typdef *) filp->private_data;
return 0;
}
static ssize_t w25qxx_write(struct file *filp, const char __user *buf, size_t count,loff_t *f_pos)
{
int ret;
unsigned char *write_buf;/*数据缓冲区*/
w25qxx_typdef * dev = (w25qxx_typdef *) filp->private_data;
unsigned char address = filp->f_pos;
write_buf = (unsigned char*)kzalloc(count,GFP_KERNEL);
if(!write_buf )
return -ENOMEM;
spi_wp_enable();
if (copy_from_user(write_buf, buf, count))
{
kfree(write_buf);
return -EFAULT;
}
printk("write = %d,count = %d\n", address, (int)count);
ret = w25qxx_write_more_bytes(dev,address,write_buf,count);
spi_wp_disable();
kfree(write_buf);
return ret;
}
static ssize_t w25qxx_read(struct file *filp,char __user *buf, size_t count,loff_t *f_pos)
{
int ret;
unsigned char *read_buf;/*数据缓冲区*/
w25qxx_typdef * dev = (w25qxx_typdef *) filp->private_data;
unsigned char address = filp->f_pos;
read_buf = (unsigned char*)kzalloc(count,GFP_KERNEL);
if(!read_buf )
return -ENOMEM;
printk("read@%d,count:%d\n",address, (int)count);
ret = w25qxx_read_bytes(dev,address,read_buf,count);
if (copy_to_user(buf, read_buf, count))
{
ret = -EFAULT;
}
kfree(read_buf);
return ret;
}
loff_t w25qxx_llseek(struct file *file, loff_t offset, int whence)
{
loff_t ret,pos,oldpos;
oldpos = file->f_pos;
switch (whence)
{
case SEEK_SET:
pos = offset;
break;
case SEEK_CUR:
pos = oldpos + offset;
break;
case SEEK_END:
pos = W25Qxx_PAGE_SIZE - offset;
break;
default:
printk("cmd not supported\n");
break;
}
if(pos < 0 || pos > W25Qxx_PAGE_SIZE)
{
printk("error: pos > W25Qxx_PAGE_SIZE !\n");
ret = -EINVAL;
return ret;
}
file->f_pos = pos;
ret = offset;
return ret;
}
static struct file_operations w25qxx_fops={
.owner = THIS_MODULE,
.open = w25qxx_open,
.write = w25qxx_write,
.read = w25qxx_read,
.release = w25qxx_release,
.llseek = w25qxx_llseek,
};
static int w25qxx_probe(struct spi_device *spi)
{
int ret = -1;
const char *string = NULL;
w25qxx_typdef *dev = &w25qxx_dev;
printk("w25q64 probe!\n");
/*获取设备节点*/
w25qxx_dev.node = of_find_node_by_path("/spi@fe620000/w25q64@0");
if(w25qxx_dev.node == NULL)
{
printk("device-tree:not found w25q64!\r\n");
return -1;
}
/*读取w25q64设备节点的compatible属性值*/
ret = of_property_read_string(w25qxx_dev.node,"compatible",&string);
if(ret == 0)
{
printk("%s\n",string);
}
/*申请gpio 用作片选*/
w25qxx_dev.wppin = of_get_named_gpio(w25qxx_dev.node,"wp-gpio",0);
if(!gpio_is_valid(w25qxx_dev.wppin))
{
printk("get gpio error\n");
ret = -EINVAL;
return ret;
}
printk("gpio = %d\n",w25qxx_dev.wppin);
ret = gpio_request(w25qxx_dev.wppin,"spi-wp");
if(ret < 0)
{
printk("gpio_request %d failed\n",w25qxx_dev.wppin);
return ret;
}
gpio_direction_output(w25qxx_dev.wppin, 1);
gpio_export(w25qxx_dev.wppin, 1);
/*申请gpio 用作片选*/
// w25qxx_dev.cspin = of_get_named_gpio(w25qxx_dev.node,"cs-gpios",0);
// if(!gpio_is_valid(w25qxx_dev.cspin))
// {
// printk("get gpio error\n");
// ret = -EINVAL;
// return ret;
// }
// printk("gpio = %d\n",w25qxx_dev.cspin);
// ret = gpio_request(w25qxx_dev.cspin,"spi-cs");
// if(ret < 0)
// {
// printk("gpio_request %d failed\n",w25qxx_dev.cspin);
// return ret;
// }
// gpio_direction_output(w25qxx_dev.cspin, 1);
// gpio_export(w25qxx_dev.cspin, 1);
/*申请设备号*/
alloc_chrdev_region(&w25qxx_dev.dev_id,0,1,DEVICE_NAME);
/*初始化一个cdev*/
cdev_init(&w25qxx_dev.cdev,&w25qxx_fops);
/*向cdev中添加一个设备*/
cdev_add(&w25qxx_dev.cdev,w25qxx_dev.dev_id,1);
/*创建一个norflash_class类*/
w25qxx_dev.class = class_create(THIS_MODULE, "norflash_class");
if(w25qxx_dev.class == NULL)
{
printk("class_create failed\r\n");
return -1;
}
/*在eeprom_class类下创建一个eeprom_class设备*/
w25qxx_dev.device = device_create(w25qxx_dev.class, NULL, w25qxx_dev.dev_id, NULL, DEVICE_NAME);
/*获取与本驱动匹配的spi设备*/
w25qxx_dev.spi = spi;
//w25qxx_dev.spi->mode = SPI_MODE_3; /*spi flash对应的模式*/
spi_setup(w25qxx_dev.spi);
mutex_init(&dev->lock);
w25qxx_Reset(&w25qxx_dev);
mdelay(200);
ret = w25qxx_erase_chip(&w25qxx_dev);
if(ret < 0)
{
printk("w25qxx_erase_chip failed\r\n");
}
ret = w25qxx_get_id(&w25qxx_dev);
printk("id=%04x\n",ret);
return 0;
}
static int w25qxx_remove(struct spi_device *spi)
{
printk("w25qxx remove!\n");
/*删除w25q64类*/
cdev_del(&w25qxx_dev.cdev);
/*释放w25q64设备号*/
unregister_chrdev_region(w25qxx_dev.dev_id, 1);
/*注销w25q64设备*/
device_destroy(w25qxx_dev.class, w25qxx_dev.dev_id);
/*注销w25q64类*/
class_destroy(w25qxx_dev.class);
gpio_free(w25qxx_dev.wppin);
//gpio_free(w25qxx_dev.cspin);
return 0;
}
static const struct of_device_id w25qxx_of_match[] = {
{.compatible = "yifeng,w25q64"},
{},
};
static const struct spi_device_id w25q64_id[] = {
{ "xxxx", 0 },
{},
};
static struct spi_driver w25qxx_driver = {
.driver = {
.owner = THIS_MODULE,
.name = "w25q64",
.of_match_table = w25qxx_of_match,
},
.probe = w25qxx_probe,
.remove = w25qxx_remove,
.id_table = w25q64_id,
};
static int __init w25qxx_init(void)
{
printk("module init ok\n");
return spi_register_driver(&w25qxx_driver);
}
static void w25qxx_exit(void)
{
spi_unregister_driver(&w25qxx_driver);
printk("module exit ok\n");
}
module_init(w25qxx_init);
module_exit(w25qxx_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("w25q64 driver");
MODULE_AUTHOR("yifeng");
代码中获取设备节点需要注意：
w25qxx_dev.node = of_find_node_by_path("/spi@fe620000/w25q64@0");
这里的**/spi@fe620000/w25q64@0**需要先在开发板上确定。
片选引脚也需要指定。
2、makefile
KERNELDIR := /home/alientek/rk3568_linux_sdk/kernel
ARCH=arm64
CROSS_COMPILE=/opt/atk-dlrk356x-toolchain/usr/bin/aarch64-buildroot-linux-gnu-
export ARCH CROSS_COMPILE
CURRENT_PATH := $(shell pwd)
obj-m := spi_drv.o
build: kernel_modules
kernel_modules:
$(MAKE) -C $(KERNELDIR) M=$(CURRENT_PATH) modules
clean:
$(MAKE) -C $(KERNELDIR) M=$(CURRENT_PATH) clean
编译生成ko文件
七、应用程序编写
// APP应用
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#include <errno.h>
#include <limits.h>
#include <asm/ioctls.h>
#include <time.h>
#include <pthread.h>
#include<string.h>
#define num 128
void print_data(const char *title, char *dat, int count)
{
int i = 0;
printf(title);
for(i = 0; i < count; i++)
{
printf(" 0x%x", dat[i]);
}
printf("\n");
}
int main(int argc, char *argv[])
{
int fd,ret,i;
int count = num;
int offset = 0;
char write_buf[num],read_buf[num];
/*判断传入的参数是否合法*/
if(argc != 2)
{
printf("Usage:error\n");
return -1;
}
/*解析传入的参数*/
offset =atoi(argv[1]);
printf("offset = %d\n", offset);
/*打开设备文件*/
fd = open("/dev/spi", O_RDWR);
if(fd < 0)
{
printf("open dev fail fd=%d\n",fd);
close(fd);
return fd;
}
/*缓存数组赋值*/
//memset(write_buf, 0x55, num);
for(i = 0; i < num; i++)
{
write_buf[i] = i;
}
/*写入数据*/
lseek(fd,offset,SEEK_SET);
ret = write(fd,write_buf,num);
if(ret < 0)
{
printf("write to w25qxx error\n");
close(fd);
return ret;
}
/*打印数据*/
print_data("write to w25qxx: \n\r", write_buf, count);
/*读取数据*/
ret = lseek(fd,offset,SEEK_SET);
printf("lseek = %d\n",ret);
ret = read(fd, read_buf, count);
if(ret < 0)
{
printf("read from w25qxx error\n");
close(fd);
return ret;
}
/*打印数据*/
print_data("read from w25qxx: \n\r",read_buf, count);
ret = memcmp(write_buf, read_buf, count);
if(ret)
{
printf("Writing data is different from reading data...\n");
}
else
{
printf("Write data is the same as read data...\n");
}
close(fd);
return 0;
}
编译
/opt/atk-dlrk356x-toolchain/bin/aarch64-buildroot-linux-gnu-gcc spiApp.c -o spiApp
八、测试
测试比较简单，写入128个数，在读出来比较。
到此测试完成，使用硬件SPI正常。
但有个疑问使用ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);是怎么处理的，留个问题。
如有侵权，或需要完整代码，请及时联系博主。