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目录

一.SPI驱动相关结构体与函数

1.struct spi_master 结构体

2.申请 spi_master - spi_alloc_master

3.释放 spi_master - spi_master_put

4.向内核注册 spi_master - spi_register_master

5.注销掉 spi_master

6.struct spi_driver 结构体

7.向内核注册 spi_driver - spi_register_driver

8.注销 spi_driver - spi_unregister_driver

9.struct spi_transfer 结构体

10.struct spi_message 结构体

11.初始化 spi_message

12.将 spi_transfer 添加到 spi_message 队列中

13.SPI 同步传输数据 - spi_sync

14.SPI 异步传输数据 - spi_async

二.SPI实验 - ICM20608

1.设备树

（1）.流程图

（2）.设备树代码

​编辑

2.驱动部分

（1）.流程图

​编辑

（2）.驱动部分代码

3.应用程序

---

一.SPI驱动相关结构体与函数

1.struct spi_master 结构体

struct spi_master 
{struct device dev;struct list_head list;......s16 bus_num;/* chipselects will be integral to many controllers; some others* might use board-specific GPIOs.*/u16 num_chipselect;/* some SPI controllers pose alignment requirements on DMAable* buffers; let protocol drivers know about these requirements.*/u16 dma_alignment;/* spi_device.mode flags understood by this controller driver */u16 mode_bits;/* bitmask of supported bits_per_word for transfers */u32 bits_per_word_mask;....../* limits on transfer speed */u32 min_speed_hz;u32 max_speed_hz;/* other constraints relevant to this driver */u16 flags;/* lock and mutex for SPI bus locking */spinlock_t bus_lock_spinlock;struct mutex bus_lock_mutex;/* flag indicating that the SPI bus is locked for exclusive use */bool bus_lock_flag;......int (*setup)(struct spi_device *spi);......int (*transfer)(struct spi_device *spi,struct spi_message *mesg);......int (*transfer_one_message)(struct spi_master *master,struct spi_message *mesg);......
};

2.申请 spi_master - spi_alloc_master

/*** @description:            申请 spi_master* @param - dev     :       设备，一般是 platform_device 中的 dev 变量* @param - size    :       私有数据大小，可以通过 spi_master_get_devdata 函数获取到这些私有数据* @return          :       申请到的 spi_master*/
struct spi_master *spi_alloc_master(struct device *dev,unsigned int size)

3.释放 spi_master - spi_master_put

/*** @description:            释放 spi_master* @param - master  :       要释放的 spi_master* @return          :       无*/
void spi_master_put(struct spi_master *master)

4.向内核注册 spi_master - spi_register_master

/*** @description:            向内核注册 spi_master* @param - master      :   要向内核注册的 spi_master* @return              :   成功则返回（0），失败则返回（-1）*/
int spi_register_master(struct spi_master *master)

5.注销掉 spi_master

/*** @description:            注销 spi_master* @param - master  :       要注销的 spi_master* @return          :       无*/
void spi_unregister_master(struct spi_master *master)

6.struct spi_driver 结构体

struct spi_driver 
{const struct spi_device_id *id_table;int (*probe)(struct spi_device *spi);int (*remove)(struct spi_device *spi);void (*shutdown)(struct spi_device *spi);struct device_driver driver;
};

7.向内核注册 spi_driver - spi_register_driver

/*** @description:            向内核注册 spi_driver* @param - sdrv        :   要注册的 spi_driver* @return              :   成功则返回（0），失败则返回（负值）*/
int spi_register_driver(struct spi_driver *sdrv)

8.注销 spi_driver - spi_unregister_driver

/*** @description:            注销 spi_driver* @param - sdrv        :   要注销的 spi_driver* @return              :   无*/
void spi_unregister_driver(struct spi_driver *sdrv)

9.struct spi_transfer 结构体

struct spi_transfer 
{/* 发送数据缓冲区 */const void *tx_buf;/* 接收数据缓冲区 */         void *rx_buf;/* 数据长度 */unsigned len;dma_addr_t tx_dma;dma_addr_t rx_dma;struct sg_table tx_sg;struct sg_table rx_sg;unsigned cs_change:1;unsigned tx_nbits:3;unsigned rx_nbits:3;#define SPI_NBITS_SINGLE 0x01 /* 1bit transfer */#define SPI_NBITS_DUAL 0x02 /* 2bits transfer */#define SPI_NBITS_QUAD 0x04 /* 4bits transfer */u8 bits_per_word;u16 delay_usecs;u32 speed_hz;struct list_head transfer_list;
};

10.struct spi_message 结构体

struct spi_message 
{struct list_head transfers;struct spi_device *spi;unsigned is_dma_mapped:1;....../* completion is reported through a callback */void (*complete)(void *context);原子哥在线教学:www.yuanzige.com 论坛:www.openedv.comvoid *context;unsigned frame_length;unsigned actual_length;int status;struct list_head queue;void *state;
};

11.初始化 spi_message

/*** @description:            初始化 spi_message* @param - m       :       要初始化的 spi_message* @return          :       无*/
void spi_message_init(struct spi_message *m)

12.将 spi_transfer 添加到 spi_message 队列中

/*** @description:            将 spi_transfer 添加到 spi_message 队列中* @param - t       :       要添加至 spi_message 队列中的 spi_transfer* @param - m       :       spi_transfer 要加入的 spi_message* @return          :       无*/
void spi_message_add_tail(struct spi_transfer *t,struct spi_message *m)

13.SPI 同步传输数据 - spi_sync

/*** @description:            SPI 同步传输数据* @param - spi         :   要进行数据传输的 SPI* @param - message     :   要传输的 spi_message* @return              :   无       */
int spi_sync(struct spi_device *spi,struct spi_message *message)

14.SPI 异步传输数据 - spi_async

/*** @description:            SPI 异步传输数据* @param - spi     :       要进行数据传输的 SPI* @param - message :       要传输的 spi_message* @return          :       无*/
int spi_async(struct spi_device *spi,struct spi_message *message)

二.SPI实验 - ICM20608

1.设备树

（1）.流程图

（2）.设备树代码

2.驱动部分

（1）.流程图

（2）.驱动部分代码

#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/i2c.h>
#include <linux/spi/spi.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_gpio.h>
#include <linux/platform_device.h>
#include <asm/mach/map.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include "icm20608reg.h"#define ICM20608_CNT    1           /* 设备数量 */
#define ICM20608_NAME   "icm20608"  /* 设备名字 *//* 设备结构体 */
struct icm20608_dev
{dev_t devid;                /* 设备号 */struct cdev cdev;           /* cdev */struct class *class;        /* 类 */struct device *device;      /* 设备 */struct device_node *nd;     /* 设备结点 */int major;                  /* 主设备号 */void *private_data;         /* 私有数据 */int cs_gpio;                /* 片选所使用的 GPIO 编号 */signed int gyro_x_adc;      /* 陀螺仪 X 轴原始值 */signed int gyro_y_adc;      /* 陀螺仪 Y 轴原始值 */signed int gyro_z_adc;      /* 陀螺仪 Z 轴原始值 */signed int accel_x_adc;     /* 加速度计 X 轴原始值 */signed int accel_y_adc;     /* 加速度计 Y 轴原始值 */signed int accel_z_adc;     /* 加速度计 Z 轴原始值 */signed int temp_adc;        /* 温度原始值 */
};static struct icm20608_dev icm20608dev;/*** @description:            从icm20608读取多个寄存器数据* @param - dev     :       icm20608设备* @param - reg     :       要读取的寄存器首地址* @param - buf     :       用于存储读到的数据* @param - len     :       要读取的数据的长度* @return          :       操作结果,0为成功，其他为失败*/
static int icm20608_read_regs(struct icm20608_dev *dev,u8 reg,void *buf,int len)
{int ret = -1;unsigned char txdata[1];        //发送的数据为要读取的寄存器首地址unsigned char *rxdata;          //存储该函数SPI整个过程接收到的数据struct spi_message m;struct spi_transfer *t;/* 获取私有数据 */struct spi_device *spi = (struct spi_device *)dev->private_data;t = kzalloc(sizeof(struct spi_transfer),GFP_KERNEL);if(!t){return -ENOMEM;}rxdata = kzalloc(sizeof(char)*len,GFP_KERNEL);if(!rxdata){goto out1;}/* 一共发送 len+1 个字节的数据，第一个字节为寄存器首地址，一共读取len个字节长度的数据 */txdata[0] = reg | 0x80;         /* 写数据的时候，首寄存器地址 bit8 要置1 */t->tx_buf = txdata;             /* 要发送的数据 */t->rx_buf = rxdata;             /* 接收数据的缓冲区 */t->len = len + 1;               /* t->len = 一个字节的寄存器首地址 + 要读取的长度 */spi_message_init(&m);           /* 初始化 spi_message */spi_message_add_tail(t,&m);     /* 将 spi_transfer 添加到 spi_message 队列中 */ret = spi_sync(spi,&m);         /* 同步发送 */if(ret){goto out2;}memcpy(buf,rxdata + 1,len);     /* 只需要读取的数据，rxdata的第一个字节的数据没有意义 */out2:kfree(rxdata);                  /* 释放内存 */out1:kfree(t);                       /* 释放内存 */return ret;
}/*** @description:            向icm20608多个寄存器写入数据* @param - dev     :       icm20608 设备* @param - reg     :       要写的寄存器首地址* @param - buf     :       要写入的数据缓冲区* @param - len     :       要写入数据的长度* @return          :       操作结果*/
static s32 icm20608_write_regs(struct icm20608_dev *dev,u8 reg,u8 *buf,u8 len)
{int ret = -1;unsigned char *txdata;struct spi_message m;struct spi_transfer *t;struct spi_device *spi = (struct spi_device *)dev->private_data;t = kzalloc(sizeof(struct spi_transfer),GFP_KERNEL);if(!t){return -ENOMEM;}txdata = kzalloc(sizeof(char) + len,GFP_KERNEL);        //第一个字节为寄存器首地址，后面的内容为要写的内容if(!txdata){goto out1;}/* 一共要发送 len+1 个字节，第一个字节为寄存器首地址，len 为要写入寄存器的集合 */*txdata = reg & ~0x80;                  /* 写数据的时候，寄存器首地址 bit8 要清零 */memcpy(txdata+1,buf,len);               /* 将要写入的数据拷贝到缓冲区中 */t->tx_buf = txdata;                     /* 要发送的数据 */t->len = len+1;                         /* t->len = 发送的数据段长度+一个字节的寄存器首地址 */spi_message_init(&m);                   /* 初始化 spi_message */spi_message_add_tail(t,&m);             /* 将 spi_transfer 添加到 spi_message 队列中 */ret = spi_sync(spi,&m);if(ret){goto out2;}out2:kfree(txdata);
out1:kfree(t);return ret;
}/*** @descsription:           读取icm20608指定寄存器的值，只读取一个字节* @param - dev         :   icm20608设备* @param - reg         :   要读取的寄存器首地址* @return              :   返回读取到的值 */
static unsigned char icm20608_read_onereg(struct icm20608_dev *dev,u8 reg)
{unsigned char data;icm20608_read_regs(dev,reg,&data,1);return data;
}/*** @description:            向icm20608指定寄存器写入一个字节的数据* @param - dev     :       icm20608设备* @param - reg     :       要写入的寄存器首地址* @param - value   :       要写入的值*/
void icm20608_write_onereg(struct icm20608_dev *dev,u8 reg,u8 value)
{u8 data = value;icm20608_write_regs(dev,reg,&data,1);
}/*** @description:            读取 icm20608 的原始数据，包括三轴陀螺仪、三轴加速度计和内部温度* @param - dev     :       icm20608 设备,读取到的数据会存入该设备结构体内* @return          :       无*/
void icm20608_readdata(struct icm20608_dev *dev)
{unsigned char data[14] = {0};icm20608_read_regs(dev,ICM20_ACCEL_XOUT_H,data,14);     //读取数据并存储在 data 缓冲区中dev->accel_x_adc = (signed short)((data[0] << 8) | data[1]);dev->accel_y_adc = (signed short)((data[2] << 8) | data[3]);dev->accel_z_adc = (signed short)((data[4] << 8) | data[5]);dev->temp_adc    = (signed short)((data[6] << 8) | data[7]);dev->gyro_x_adc  = (signed short)((data[8] << 8) | data[9]);dev->gyro_y_adc  = (signed short)((data[10] << 8) | data[11]);dev->gyro_z_adc  = (signed short)((data[12] << 8) | data[13]);
}/*** @description:            内部寄存器初始化函数* @param           :       无* @return          :       无*/
void icm20608_reginit(void)
{u8 value = 0;icm20608_write_onereg(&icm20608dev,ICM20_PWR_MGMT_1,0X80);mdelay(50);icm20608_write_onereg(&icm20608dev,ICM20_PWR_MGMT_1,0X81);mdelay(50);/* 获取 ICM20608 设备ID */value = icm20608_read_onereg(&icm20608dev,ICM20_WHO_AM_I);printk("ICM20608 ID = %#X\r\n",value);icm20608_write_onereg(&icm20608dev,ICM20_SMPLRT_DIV,0X00);icm20608_write_onereg(&icm20608dev,ICM20_GYRO_CONFIG,0X18);icm20608_write_onereg(&icm20608dev,ICM20_ACCEL_CONFIG,0X18);icm20608_write_onereg(&icm20608dev,ICM20_CONFIG,0X04);icm20608_write_onereg(&icm20608dev,ICM20_ACCEL_CONFIG2,0X04);icm20608_write_onereg(&icm20608dev,ICM20_PWR_MGMT_2,0X00);icm20608_write_onereg(&icm20608dev,ICM20_LP_MODE_CFG,0X00);icm20608_write_onereg(&icm20608dev,ICM20_FIFO_EN,0X00);
}/*** @description:            打开设备* @param - inode   :       传递给驱动的inode* @param - filp    :       设备文件，一般使 filp->private_data 指向设备结构体* @return          :       0成功，其他失败*/
static int icm20608_open(struct inode *inode,struct file *filp)
{/* 设置私有数据 */filp->private_data = &icm20608dev;return 0;
}/*** @description:            从设备读取数据* @param - filp    :       要打开的设备* @param - buf     :       返回给用户空间的数据缓冲区* @param - cnt     :       要读取的字节数* @param - offt    :       相对于文件首地址的偏移量* @return          :       成功则返回（读取到的字节数），失败则返回（负值）*/
static ssize_t icm20608_read(struct file *filp,char __user *buf,size_t cnt,loff_t *offt)
{signed int data[7];long err = 0;struct icm20608_dev *dev = (struct icm20608_dev *)filp->private_data;icm20608_readdata(dev);data[0] = dev->gyro_x_adc;data[1] = dev->gyro_y_adc;data[2] = dev->gyro_z_adc;data[3] = dev->accel_x_adc;data[4] = dev->accel_y_adc;data[5] = dev->accel_z_adc;data[6] = dev->temp_adc;err = copy_to_user(buf,data,sizeof(data));return 0;
}/*** @description:            关闭/释放设备* @param           :       无* @return          :       0成功，其他失败*/
static int icm20608_release(struct inode *inode,struct file *filp)
{return 0;
}/* 设备操作函数  */
static const struct file_operations icm20608_ops = 
{.owner = THIS_MODULE,.open = icm20608_open,.read = icm20608_read,.release = icm20608_release,
};/*** @description:            probe函数，当设备与驱动匹配成功后就会执行此函数* @param - spi     :       spi 设备* @return          :       0成功，其他失败*/
static int icm20608_probe(struct spi_device *spi)
{printk("driver and device matched!\r]n");/* 1.构建设备号 */if(icm20608dev.major){icm20608dev.devid = MKDEV(icm20608dev.major,0);register_chrdev_region(icm20608dev.devid,ICM20608_CNT,ICM20608_NAME);}else{alloc_chrdev_region(&icm20608dev.devid,0,ICM20608_CNT,ICM20608_NAME);icm20608dev.major = MAJOR(icm20608dev.devid);}/* 2.注册cdev */cdev_init(&icm20608dev.cdev,&icm20608_ops);cdev_add(&icm20608dev.cdev,icm20608dev.devid,ICM20608_CNT);/* 3.创建类 */icm20608dev.class = class_create(THIS_MODULE,ICM20608_NAME);if(IS_ERR(icm20608dev.class)){return PTR_ERR(icm20608dev.class);}/* 4.创建设备 */icm20608dev.device = device_create(icm20608dev.class,NULL,icm20608dev.devid,NULL,ICM20608_NAME);if(IS_ERR(icm20608dev.device)){return PTR_ERR(icm20608dev.device);}/* 初始化 spi_device */spi->mode = SPI_MODE_0;     /* MODE0 : CPOL=0,CPHA=0 */spi_setup(spi);icm20608dev.private_data = spi;     //设置私有数据/* 初始化 ICM20608 内部寄存器 */icm20608_reginit();return 0;
}/*** @description:            remove函数，移除SPI驱动的时候会执行此函数* @param - spi     :       spi设备* @return          :       成功则返回（0），失败则返回（其他值）*/
static int icm20608_remove(struct spi_device *spi)
{/* 1.删除设备 */cdev_del(&icm20608dev.cdev);unregister_chrdev_region(icm20608dev.devid,ICM20608_CNT);/* 注销掉类和设备 */device_destroy(icm20608dev.class,icm20608dev.devid);class_destroy(icm20608dev.class);return 0;
}/* 无设备树下的匹配方式 - ID列表 */
static const struct spi_device_id icm20608_id[] = 
{{"alientek,icm20608",0},{}
};/* 设备树下的匹配方式 - 匹配列表 */
static const struct of_device_id icm20608_of_match[] = 
{{.compatible = "alientek,icm20608"},{}
};/* SPI驱动结构体 */
static struct spi_driver icm20608_driver = 
{.probe = icm20608_probe,.remove = icm20608_remove,.driver = {.owner = THIS_MODULE,.name = "icm20608",.of_match_table = icm20608_of_match,        //设备树下的匹配列表},.id_table = icm20608_id,                        //无设备树下的 ID列表
};/*** @description:            驱动入口函数* @param           :       无* @return          :       无*/
static int __init icm20608_init(void)
{return spi_register_driver(&icm20608_driver);
}/*** @description:            驱动出口函数* @param           :       无* @return          :       无*/
static void __exit icm20608_exit(void)
{spi_unregister_driver(&icm20608_driver);
}module_init(icm20608_init);
module_exit(icm20608_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("kaneki");

3.应用程序

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>int main(int argc, char  *argv[])
{int ret,fd;char *filename;signed int databuf[7];unsigned char data[14];/* icm20608的原始值 */signed int gyro_x_adc,gyro_y_adc,gyro_z_adc;signed int accel_x_adc,accel_y_adc,accel_z_adc;signed int temp_adc;/* icm20608的实际值 */ float gyro_x_act,gyro_y_act,gyro_z_act;float accel_x_act,accel_y_act,accel_z_act;float temp_act;if(2 != argc){printf("Usage : ./%s <dev_path>\n",argv[0]);return -1;}filename = argv[1];fd = open(filename,O_RDONLY);if(0 > fd){perror("open error");return -1;}while(1){ret = read(fd,databuf,sizeof(databuf));/* 读取成功 */if(0 == ret){/* 得到原始值 */gyro_x_adc = databuf[0];gyro_y_adc = databuf[1];gyro_z_adc = databuf[2];accel_x_adc = databuf[3];accel_y_adc = databuf[4];accel_z_adc = databuf[5];temp_adc = databuf[6];/* 计算得到实际值 */gyro_x_act = (float)(gyro_x_adc) / 16.4;gyro_y_act = (float)(gyro_y_adc) / 16.4;gyro_z_act = (float)(gyro_z_adc) / 16.4;accel_x_act = (float)(accel_x_adc) / 2048;accel_y_act = (float)(accel_y_adc) / 2048;accel_z_act = (float)(accel_z_adc) / 2048;temp_act = ((float)(temp_adc - 25) / 326.8 + 25);printf("----原始值-----\n");printf("gx = %d,gy = %d,gz = %d\n",gyro_x_adc,gyro_y_adc,gyro_z_adc);printf("ax = %d,ay = %d,az = %d\n",accel_x_adc,accel_y_adc,accel_z_adc);printf("temp = %d\n",temp_adc);printf("----实际值----\n");printf("act gx = %.2f,act gy = %.2f,act gz = %.2f\n",gyro_x_act,gyro_y_act,gyro_z_act);printf("act ax = %.2f,act ay = %.2f,act az = %.2f\n",accel_x_act,accel_y_act,accel_z_act);printf("act temp = %.2f\n",temp_act);}usleep(100000); /* 100ms*/}close(fd);return 0;
}