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RK3568笔记四十九：W25Q64驱动开发（硬件SPI1)

news 文章来源：https://blog.csdn.net/weixin_38807927/article/details/140833341 2025/1/18 10:00:41

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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 0spi-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_addressunsigned 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_COMPILECURRENT_PATH := $(shell pwd)
obj-m := spi_drv.obuild: kernel_moduleskernel_modules:$(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 128void 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。