700字范文 > Linux驱动开发——正点原子IMX6ULL核心板ADS1256驱动开发

Linux驱动开发——正点原子IMX6ULL核心板ADS1256驱动开发

时间：2019-04-24 20:25:13

正点原子IMX6ULL核心板ADS1256驱动开发

一、修改设备树文件

查看正点原子IMX6ULL核心板和底板原理图，决定与 icm20608 共用 ecspi3。

找到 “imx6ull-alientek-emmc.dts” 和 “imx6ull-14x14-evk.dts”，在 “&iomuxc”下修改 “pinctrl_ecspi3” 子节点，添加“pinctrl_ads1256”，子节点。

pinctrl_ecspi3: ecspi3grp {fsl,pins = <MX6UL_PAD_UART2_RTS_B__ECSPI3_MISO 0x100b1 /* MISO */MX6UL_PAD_UART2_CTS_B__ECSPI3_MOSI 0x100b1 /* MOSI */MX6UL_PAD_UART2_RX_DATA__ECSPI3_SCLK0x100b1 /* CLK */>;};pinctrl_ads1256: ads1256 {fsl,pins = <MX6UL_PAD_UART2_TX_DATA__GPIO1_IO20 0x100b0 /* CS0, icm20608片选 */MX6UL_PAD_UART3_RX_DATA__GPIO1_IO250x100b1 /* CS, ads1256片选 */MX6UL_PAD_GPIO1_IO01__GPIO1_IO010x100b1 /* RESET, ads1256复位 */MX6UL_PAD_JTAG_MOD__GPIO1_IO100x130b1 /* DRDY, ads1256就绪 */>;};

将使用相同引脚的设备节点设置为“disabled”状态

在“&ecspi3”节点下添加 “ads1256” 节点

&ecspi3 {fsl,spi-num-chipselects = <1>;// cs-gpios = <&gpio1 20 GPIO_ACTIVE_LOW &gpio1 25 GPIO_ACTIVE_LOW>;// cs-gpios = <&gpio1 25 GPIO_ACTIVE_LOW>;pinctrl-names = "default";pinctrl-0 = <&pinctrl_ecspi3>;status = "okay";// spi3dev0: icm20608@0 {// compatible = "alientek,icm20608";//spi-max-frequency = <8000000>;//reg = <0>;// };spidev: ads1256@0 {compatible = "alientek,ads1256";spi-max-frequency = <1000000>;status = "okay";reg = <0>;pinctrl-0 = <&pinctrl_ads1256>;reset-gpio = <&gpio1 1 GPIO_ACTIVE_LOW>;drdy-gpio = <&gpio1 10 GPIO_ACTIVE_HIGH>;cs-gpio = <&gpio1 25 GPIO_ACTIVE_LOW>;cs0-gpio = <&gpio1 20 GPIO_ACTIVE_LOW>;};};

使用开发板资料提供的编译工具，编译设备树文件，更新到开发板。

二、编写驱动程序

ads1256.c

#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.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 "ads1256.h"#include <linux/unistd.h>/***************************************************************Copyright © ALIENTEK Co., Ltd. 1998-2029. All rights reserved.文件名: ads1256.c作者 : 刘明鑫版本 : V1.0描述 : ADS1256 SPI驱动程序其他 : 无日志 : 初版V1.0 /07/31 刘明鑫创建***************************************************************/#define ADS1256_CNT 1#define ADS1256_NAME "ads1256"#define ADS1256_TRANSFORM_TIME_US309/* 总线注册注销 */static int ads1256_probe(struct spi_device *spi);static int ads1256_remove(struct spi_device *spi);/* 文件操作函数集 */static int ads1256_open(struct inode *inode, struct file *filp);static ssize_t ads1256_write(struct file *filp, const char __user *buf, size_t cnt, loff_t *offt);static ssize_t ads1256_read(struct file *filp, char __user *buf, size_t cnt, loff_t *off);static int ads1256_release(struct inode *inode, struct file *filp);struct ads1256_dev{dev_t devid;/* 设备号 */struct cdev cdev;/* cdev */struct class *class;/* 类 */struct device *device;/* 设备 */struct device_node *nd; /* 设备节点 */int major;/* 主设备号 */int cs0_gpio;/* icm20608使用的片选，因为接了下拉电阻，所以需要手动上拉，停止启用 */int cs_gpio;/* cs所使用的GPIO编号 */int reset_gpio;/* reset所使用的GPIO编号 */int drdy_gpio;/* drdy所使用的GPIO编号 */unsigned char channels[8];/* 采样通道，最多8个 */unsigned char channel_num;/* 采样通道数量 */int delay_us;/* 采样间隔时间 */void *private_data;/* 私有数据 */};static struct ads1256_dev ads1256dev;/* 传统匹配方式ID列表 */static const struct spi_device_id ads1256_id[] = {{"alientek,ads1256", 0},{}};/* 设备树匹配列表 */static const struct of_device_id ads1256_of_match[] = {{.compatible = "alientek,ads1256"},{/* Sentinel */}};/* SPI驱动结构体 */static struct spi_driver ads1256_driver = {.probe = ads1256_probe,.remove = ads1256_remove,.driver = {.owner = THIS_MODULE,.name = "ads1256",.of_match_table = ads1256_of_match,},.id_table = ads1256_id,};/* ads1256操作函数 */static const struct file_operations ads1256_ops = {.owner = THIS_MODULE,.open = ads1256_open,.read = ads1256_read,.write = ads1256_write,.release = ads1256_release,};static int ads1256_transfer_multibyte(struct ads1256_dev *dev, unsigned char *wbuf, unsigned char *rbuf, unsigned char len){int ret = 0;struct spi_message m;struct spi_transfer t = {0};struct spi_device *spi = (struct spi_device *)dev->private_data;/* 一共发送len个字节的数据*/t.tx_buf = wbuf; /* 要发送的数据 */t.rx_buf = rbuf;t.len = len; /* 传输长度 */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 */ret = spi_sync(spi, &m); /* 同步发送 */return -ret;}/** @description: 数据传输* @param - dev : ads1256设备* @param - byte: 要通过spi总线发送的数据* @return : 通过spi总线接收到的数据*/static unsigned char ads1256_transfer(struct ads1256_dev *dev, unsigned char byte){int ret = -1;unsigned char txdata[1];unsigned char rxdata[1];struct spi_message m;struct spi_transfer t = {0};struct spi_device *spi = (struct spi_device *)dev->private_data;/* 一共发送1个字节的数据，第一个字节为寄存器首地址，一共要读取len个字节长度的数据，*/txdata[0] = byte | 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; /* 要读取的数据 */t.len = 1; /* 发送的长度 */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 */ret = spi_sync(spi, &m); /* 同步发送 */if (ret){rxdata[0] = 0;}return rxdata[0];}static int ads1256_read_channel(struct ads1256_dev *dev, unsigned char channel){unsigned char i = 0;unsigned int r = 0;int sum = 0;unsigned char wbuf[8];unsigned char rbuf[8];/* 设置采样通道 */gpio_set_value(dev->cs_gpio, 0);while (gpio_get_value(dev->drdy_gpio));wbuf[0] = ADS1256_CMD_WREG | (ADS1256_MUX & 0xF);wbuf[1] = 0;ads1256_transfer_multibyte(dev, wbuf, rbuf, 2);wbuf[0] = channel;ads1256_transfer_multibyte(dev, wbuf, rbuf, 1);while (gpio_get_value(dev->drdy_gpio));/* 读取转换结果 */wbuf[0] = ADS1256_CMD_SYNC;wbuf[1] = ADS1256_CMD_WAKEUP;wbuf[2] = ADS1256_CMD_RDATA;ads1256_transfer_multibyte(dev, wbuf, rbuf, 3);wbuf[0] = 0xFF;wbuf[1] = 0xFF;wbuf[2] = 0xFF;memset(rbuf, 0, 3);ads1256_transfer_multibyte(dev, wbuf, rbuf, 3);for (i = 0; i < 3; i++){sum = sum << 8;r = rbuf[i];sum |= r;}if (sum > 0x7FFFFF){ // 负值转换sum = sum + 0xFF000000;}while (gpio_get_value(dev->drdy_gpio));gpio_set_value(dev->cs_gpio, 1);return sum;}/* * | 命令 | 参数长度 | 参数 |* | 1 | 1 | n |*/struct write_data{unsigned char cmd;unsigned char length;unsigned char param[8]; /* 最多8个参数 */};static int ads1256_write_string_to_dev(struct ads1256_dev *dev, const char *buf, size_t cnt){size_t index = 0;struct write_data *data_p;int temp;while (index < cnt){if (cnt - index < 3){return index;}data_p = (struct write_data *)&buf[index];switch (data_p->cmd){case SET_CHANNELS:if (data_p->length > 8 || index + 1 + data_p->length >= cnt){return index;/* 参数错误或剩余长度不够 */}dev->channel_num = data_p->length; /* 设置通道数量 */memcpy(dev->channels, data_p->param, dev->channel_num); /* 设置通道序列 */ads1256_read_channel(dev, dev->channels[0]);/* 重置通道 */index = index + data_p->length + 2;break;case SET_FREQUENCY:if (data_p->length != 4 || index + 1 + data_p->length >= cnt){return index;/* 参数错误或剩余长度不够 */}temp = (data_p->param[0] << 24) + (data_p->param[1] << 16) + (data_p->param[2] << 8) + data_p->param[3];temp = 1000000 / temp - ADS1256_TRANSFORM_TIME_US;dev->delay_us = temp > 0 ? temp : 0;index = index + data_p->length + 2;break;default:return index;}}return index;}/** @description: 打开设备* @param - inode : 传递给驱动的inode* @param - filp : 设备文件，file结构体有个叫做pr似有ate_data的成员变量* 一般在open的时候将private_data似有向设备结构体。* @return : 0 成功;其他失败*/static int ads1256_open(struct inode *inode, struct file *filp){filp->private_data = &ads1256dev; /* 设置私有数据 */return 0;}/** @description: 向设备写数据* @param - filp : 设备文件，表示打开的文件描述符* @param - buf : 要写给设备写入的数据* @param - cnt : 要写入的数据长度* @param - offt : 相对于文件首地址的偏移* @return : 写入的字节数，如果为负值，表示写入失败*/static ssize_t ads1256_write(struct file *filp, const char __user *buf, size_t cnt, loff_t *offt){int retvalue;unsigned char *databuf;struct ads1256_dev *dev = (struct ads1256_dev *)filp->private_data;databuf = kzalloc(cnt, GFP_KERNEL);if (!databuf){return -ENOMEM;}retvalue = copy_from_user(databuf, buf, cnt);if (retvalue < 0){printk("kernel write failed!\r\n");retvalue = -EFAULT;goto out1;}retvalue = ads1256_write_string_to_dev(dev, databuf, cnt);out1:kfree(databuf);return retvalue;}/** @description: 从设备读取数据* @param - filp : 要打开的设备文件(文件描述符)* @param - buf : 返回给用户空间的数据缓冲区* @param - cnt : 要读取的数据长度* @param - offt : 相对于文件首地址的偏移* @return : 读取的字节数，如果为负值，表示读取失败*/static ssize_t ads1256_read(struct file *filp, char __user *buf, size_t cnt, loff_t *off){int err = 0;int *result;int length;int index = 1;/* 从1开始，实际采样是从通道0开始 */struct ads1256_dev *dev = (struct ads1256_dev *)filp->private_data;/* 计算采样点个数 */length = cnt / 4;/* 开内存空间 */result = kzalloc(length * 4, GFP_KERNEL);if (!result){return -ENOMEM;}/* 采样 */while (index < length + 1){result[index - 1] = ads1256_read_channel(dev, dev->channels[index % dev->channel_num]);index++;udelay(dev->delay_us);}/* 重置通道 */ads1256_read_channel(dev, dev->channels[0]);err = copy_to_user(buf, result, length * 4);kfree(result);return length * 4;}/** @description: 关闭/释放设备* @param - filp : 要关闭的设备文件(文件描述符)* @return : 0 成功;其他失败*/static int ads1256_release(struct inode *inode, struct file *filp){return 0;}/** ads1256内部寄存器初始化函数* @param : 无* @return : 无*/void ads1256_reginit(struct ads1256_dev *dev){unsigned char wbuf[8];unsigned char rbuf[8];gpio_set_value(dev->cs_gpio, 1);gpio_set_value(dev->reset_gpio, 0);mdelay(2);gpio_set_value(dev->reset_gpio, 1);mdelay(20);gpio_set_value(dev->cs_gpio, 0);usleep_range(100, 200);ads1256_transfer(dev, ADS1256_CMD_REST);mdelay(10);while (gpio_get_value(dev->drdy_gpio));wbuf[0] = ADS1256_CMD_SYNC;wbuf[1] = ADS1256_CMD_WAKEUP;ads1256_transfer_multibyte(dev, wbuf, rbuf, 2);while (gpio_get_value(dev->drdy_gpio));wbuf[0] = ADS1256_CMD_WREG | ADS1256_STATUS;wbuf[1] = 3;wbuf[2] = 0x04;wbuf[3] = dev->channels[0];wbuf[4] = ADS1256_GAIN_1;wbuf[5] = ADS1256_DRATE_30000SPS;ads1256_transfer_multibyte(dev, wbuf, rbuf, 6);usleep_range(100, 200);while (gpio_get_value(dev->drdy_gpio));ads1256_transfer(dev, ADS1256_CMD_SELFCAL);gpio_set_value(dev->cs_gpio, 1);mdelay(100);}/** @description: spi驱动的probe函数，当驱动与*设备匹配以后此函数就会执行* @param - spi: spi设备**/static int ads1256_probe(struct spi_device *spi){int ret;/* 1、构建设备号 */if (ads1256dev.major){ads1256dev.devid = MKDEV(ads1256dev.major, 0);register_chrdev_region(ads1256dev.devid, ADS1256_CNT, ADS1256_NAME);}else{alloc_chrdev_region(&ads1256dev.devid, 0, ADS1256_CNT, ADS1256_NAME);ads1256dev.major = MAJOR(ads1256dev.devid);}/* 2、注册设备 */cdev_init(&ads1256dev.cdev, &ads1256_ops);cdev_add(&ads1256dev.cdev, ads1256dev.devid, ADS1256_CNT);/* 3、创建类 */ads1256dev.class = class_create(THIS_MODULE, ADS1256_NAME);if (IS_ERR(ads1256dev.class)){return PTR_ERR(ads1256dev.class);}/* 4、创建设备 */ads1256dev.device = device_create(ads1256dev.class, NULL, ads1256dev.devid, NULL, ADS1256_NAME);if (IS_ERR(ads1256dev.device)){return PTR_ERR(ads1256dev.device);}/*初始化spi_device */spi->mode = SPI_MODE_1; /*MODE1，CPOL=0，CPHA=1*/spi_setup(spi);ads1256dev.private_data = spi; /* 设置私有数据 *//* 设置ads1256所使用的GPIO *//* 1、获取设备节点：ads1256 */ads1256dev.nd = of_find_node_by_path("/soc/aips-bus@02000000/spba-bus@02000000/ecspi@0000/ads1256@0");if (ads1256dev.nd == NULL){printk("ads1256 node not find!\r\n");return -EINVAL;}else{printk("ads1256 node find!\r\n");}/* 2、获取设备树中的gpio属性 */ads1256dev.cs0_gpio = of_get_named_gpio(ads1256dev.nd, "cs0-gpio", 0);ads1256dev.cs_gpio = of_get_named_gpio(ads1256dev.nd, "cs-gpio", 0);ads1256dev.reset_gpio = of_get_named_gpio(ads1256dev.nd, "reset-gpio", 0);ads1256dev.drdy_gpio = of_get_named_gpio(ads1256dev.nd, "drdy-gpio", 0);if (ads1256dev.drdy_gpio < 0 || ads1256dev.reset_gpio < 0 || ads1256dev.cs_gpio < 0 || ads1256dev.cs0_gpio < 0){printk("can't get all gpio");return -EINVAL;}printk("ads1256 cs0-gpio num = %d\r\n", ads1256dev.cs0_gpio);printk("ads1256 cs-gpio num = %d\r\n", ads1256dev.cs_gpio);printk("ads1256 reset-gpio num = %d\r\n", ads1256dev.reset_gpio);printk("ads1256 drdy-gpio num = %d\r\n", ads1256dev.drdy_gpio);/* 3、配置输入输出* 设置cs1-gpio为输出* 设置reset-gpio为输出* 设置drdy-gpio为输入 */ret = gpio_direction_output(ads1256dev.cs0_gpio, 1);ret = gpio_direction_output(ads1256dev.cs_gpio, 1);ret = gpio_direction_output(ads1256dev.reset_gpio, 1);ret = gpio_direction_input(ads1256dev.drdy_gpio);if (ret < 0){printk("can't set gpio!\r\n");}/* 初始化通道和延时 */ads1256dev.delay_us = 100;ads1256dev.channel_num = 1;ads1256dev.channels[0] = ADS1256_MUXP_AIN0 | ADS1256_MUXN_AIN1;/* 初始化ads1256内部寄存器 */ads1256_reginit(&ads1256dev);return 0;}/** @description: spi驱动的remove函数，移除spi驱动的时候此函数会执行* @param - spi : spi设备* @return: 0，成功;其他负值,失败*/static int ads1256_remove(struct spi_device *spi){/* 注销设备的时候关闭片选 */gpio_set_value(ads1256dev.cs_gpio, 1);/* 删除设备 */cdev_del(&ads1256dev.cdev);unregister_chrdev_region(ads1256dev.devid, ADS1256_CNT);/* 注销掉类和设备 */device_destroy(ads1256dev.class, ads1256dev.devid);class_destroy(ads1256dev.class);return 0;}/** @description: 驱动入口函数* @param : 无* @return : 无*/static int __init ads1256_init(void){return spi_register_driver(&ads1256_driver);}/** @description: 驱动出口函数* @param : 无* @return : 无*/static void __exit ads1256_exit(void){spi_unregister_driver(&ads1256_driver);}module_init(ads1256_init);module_exit(ads1256_exit);MODULE_LICENSE("GPL");MODULE_AUTHOR("liumingxin");

ads1256.h

#ifndef __ADS1256_H__#define __ADS1256_H__#ifdef __cplusplusextern "C" {#endif#define ADS1256_MUXP_AIN0 0x00#define ADS1256_MUXP_AIN1 0x10#define ADS1256_MUXP_AIN2 0x20#define ADS1256_MUXP_AIN3 0x30#define ADS1256_MUXP_AIN4 0x40#define ADS1256_MUXP_AIN5 0x50#define ADS1256_MUXP_AIN6 0x60#define ADS1256_MUXP_AIN7 0x70#define ADS1256_MUXP_AINCOM 0x80#define ADS1256_MUXN_AIN0 0x00#define ADS1256_MUXN_AIN1 0x01#define ADS1256_MUXN_AIN2 0x02#define ADS1256_MUXN_AIN3 0x03#define ADS1256_MUXN_AIN4 0x04#define ADS1256_MUXN_AIN5 0x05#define ADS1256_MUXN_AIN6 0x06#define ADS1256_MUXN_AIN7 0x07#define ADS1256_MUXN_AINCOM 0x08enum write_cmd{SET_CHANNELS = 0,SET_FREQUENCY};int ads1256_init(const char *filename);void ads1256_deinit(int fd);int ads1256_set_frequency(int fd, int frequency);int ads1256_set_channels(int fd, const unsigned char *channels, unsigned char num);int ads1256_read_voltage(int fd, float *buf, int length);#ifdef __cplusplus}#endif#endif // !__LIBADS1256_H__

Makefile

#先写生成的中间文件是什么，-m 的意思是把我们的驱动编译成模块NAME = ads1256obj-m += $(NAME).o#KDIR: 内核源码所在路径KDIR:=/home/lmx/workplace/IMX6ULL/linux-imx-4.1.15-2.1.0-g0423506-v2.2#PWD: 获取当前目录的变量PWD?=$(shell pwd)#make 会进入内核源码的路径，然后把当前路径下的代码编译成模块all:make -C $(KDIR) M=$(PWD) modules#-C表示指定进入指定的目录即KERN，是内核源代码目录，调用该目录顶层下的Makefile,目标为modules。#M=$(PWD)选项让该Makefile在构造modules目标之前返回到模块源代码目录并在当前目录生成obj-m指定的xxx.o目标模块。clean:rm $(NAME).o $(NAME).ko $(NAME).mod.o $(NAME).mod.c modules.order Module.symvers

注意编译前先设置好环境变量

export ARCH=armexport CROSS_COMPILE=arm-linux-gnueabihf-

将编译好的模块 “ads1256.ko” 拷贝到NFS共享目录下。

开发板挂载NFS共享目录：

mount -t nfs -o nolock,nfsvers=3,vers=3 192.168.3.85:/home/lmx/workplace/share /mnt/nfs

取消挂载:

umount /mnt/nfs

使用 lsmod 命令发现已经加载了 icm20608 模块，先将模块注销，然后加载模块

rmmod icm20608insmod ads1256.ko

三、编写应用层库

ads1256.c

#include "unistd.h"#include "sys/types.h"#include "sys/stat.h"#include "sys/ioctl.h"#include <poll.h>#include <sys/select.h>#include <signal.h>#include <fcntl.h>#include "ads1256.h"#include "stdlib.h"#define REFERENCE_VOLTAGE 5union Data{unsigned char data_8[4];int data_32;};int ads1256_init(const char *filename){int fd;fd = open(filename, O_RDWR);if (fd < 0){return -1;}return fd;}void ads1256_deinit(int fd){close(fd); /* 关闭文件 */}int ads1256_set_frequency(int fd, int frequency){int ret = 0;unsigned char buf[6];buf[0] = SET_FREQUENCY;buf[1] = 4;buf[2] = frequency >> 24;buf[3] = frequency >> 16;buf[4] = frequency >> 8;buf[5] = frequency & 0xFF;ret = write(fd, buf, 6);if (ret != 6){return -1;}return 0;}int ads1256_set_channels(int fd, const unsigned char *channels, unsigned char num){int ret = 0;int i;unsigned char buf[10];if (num > 8){return -1;}buf[0] = SET_CHANNELS;buf[1] = num;for (i = 0; i < num; i++){buf[2 + i] = channels[i];}ret = write(fd, buf, num + 2);if (ret != num + 2){return -1;}return 0;}int ads1256_read_voltage(int fd, float *buf, int length){union Data *databuf;int ret;int i;databuf = malloc(sizeof(union Data) * length);if (!databuf){return -1;}ret = read(fd, databuf, length * 4);for (i = 0; i < ret / 4; i++){buf[i] = (float)(REFERENCE_VOLTAGE * databuf[i].data_32) / 0x800000;}free(databuf);return ret / 4;}

ads1256.h

编译成静态库：

arm-linux-guneabihf-gcc -c ads1256.carm-linux-gnueabihf-ar rcs libads1256.a ads1256.o

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