• 正文
    • 修改設備樹
    • 編寫elf-aht20.c驅(qū)動
    • 完整的驅(qū)動elf-aht20.c源碼
    • 編譯
    • 編寫測試應用源碼aht20_app.c
    • 編譯應用
    • 測試
  • 相關推薦
申請入駐 產(chǎn)業(yè)圖譜

飛凌嵌入式ElfBoard ELF 1板卡-I2C設備驅(qū)動之I2C驅(qū)動之溫濕度傳感器

04/15 10:20
276
加入交流群
掃碼加入
獲取工程師必備禮包
參與熱點資訊討論

例程代碼路徑：ELF 1開發(fā)板資料包3-例程源碼3-2 驅(qū)動例程源碼7_I2C驅(qū)動-aht20

下面編寫一個溫濕度傳感器的驅(qū)動，來了解I2C驅(qū)動的具體使用。

修改設備樹

（一）查看原理圖和引腳復用表格，確定溫濕度傳感器連接引腳。

（二）I2C引腳復用，打開設備樹文件arch/arm/boot/dts/imx6ull-elf1-emmc.dts我們看到原來的設備樹文件已經(jīng)添加了pinctrl_i2c1子節(jié)點,而且選擇的引腳與UART4_TX_DATA、UART4_RX_DATA一致，所以此處無需修改：

（三）添加設備節(jié)點

在arch/arm/boot/dts/imx6ull-elf1-emmc.dts文件中的i2c1節(jié)點下添加溫濕度傳感器子節(jié)點aht20：

aht20@38 {

compatible = "elf,aht20";

reg = <0x38>;

status = "okay";

};

自帶的mag3110和fxls8471沒有用到，所以將其屏蔽掉添加后的效果如下：

（四）編譯設備樹：

. /opt/fsl-imx-x11/4.1.15-2.0.0/environment-setup-cortexa7hf-neon-poky-linux-gnueabi

elf@ubuntu:~/work/linux-imx-imx_4.1.15_2.0.0_ga$ make dtbs

編譯生成的設備樹文件為imx6ull-elf1-emmc.dtb，參考《01-0 ELF1、ELF1S開發(fā)板_快速啟動手冊_V1》4.4節(jié)單獨更新設備樹。

編寫elf-aht20.c驅(qū)動

（一）在驅(qū)動中要操作很多芯片相關的寄存器，所以需要先新建一個i2c_aht20.h的頭文件，用來定義相關寄存器值。

#ifndef I2C_AHT20_H

#define I2C_AHT20_H

#define AHT20_STATUS_CALI_SHIFT 3 ??????// bit[3] CAL Enable

#define AHT20_STATUS_CALI_MASK ?(0x1<<AHT20_STATUS_CALI_SHIFT)

#define AHT20_STATUS_CALI(status) ((status & AHT20_STATUS_CALI_MASK) >> AHT20_STATUS_CALI_SHIFT)

// bit[2:0] Reserved

#define AHT20_STATUS_BUSY_SHIFT 7 ??????// bit[7] Busy indication

#define AHT20_STATUS_BUSY_MASK ?(0x1<<AHT20_STATUS_BUSY_SHIFT)

#define AHT20_STATUS_BUSY(status) ((status & AHT20_STATUS_BUSY_MASK) >> AHT20_STATUS_BUSY_SHIFT)

#define AHT20_CMD_STATUS ???????0x71

#define AHT20_CMD_RESET ????????0xBA

#define AHT20_CMD_TRIGGER ??????0xAC

#define AHT20_CMD_TRIGGER_ARG0 ?0x33

#define AHT20_CMD_TRIGGER_ARG1 ?0x00

#define AHT20_CMD_CALIBRATION ??????0xBE

#define AHT20_CMD_CALIBRATION_ARG0 ?0x08

#define AHT20_CMD_CALIBRATION_ARG1 ?0x00

#define AHT20_STARTUP_TIME ????20 //ms

#define AHT20_CALIBRATION_TIME 40 //ms

#define AHT20_MEASURE_TIME ????75 //ms

#define AHT20_MAX_RETRY 5

#define AHT20_RESOLUTION ???????????????(1<<20)

#endif

（二）elf-aht20.c文件編寫

（1）頭文件引用

#include <linux/init.h>

#include <linux/module.h>

#include <linux/fs.h>

#include <linux/cdev.h>

#include <linux/uaccess.h>

#include <linux/i2c.h>

#include <linux/types.h>

#include <linux/kernel.h>

#include <linux/delay.h>

#include <linux/ide.h>

#include <linux/errno.h>

#include <linux/gpio.h>

#include <asm/mach/map.h>

#include <linux/of.h>

#include <linux/of_address.h>

#include <linux/of_gpio.h>

#include <asm/io.h>

#include <linux/device.h>

#include <linux/platform_device.h>

#include “i2c_aht20.h”

（2）創(chuàng)建相關宏定義和變量

#define DEV_NAME "aht20" ?/*設備名稱*/

#define DEV_CNT (1)

/* Private typedef -----------------------------------------------------------*/

/* aht20設備結(jié)構體 */

typedef struct {

dev_t devid; ???????????????????/* 設備號 */

struct cdev cdev; ??????????????/* cdev */

struct class *class; ???/* 類 */

struct device *device; ?/* 設備 */

struct device_node *nd; /*設備節(jié)點 */

int major; ?????????????????????????????/*主設備號 */

void *private_data; ????????????/* 私有數(shù)據(jù) */

unsigned short ir, als, ps; ????/* 光傳感數(shù)據(jù) */

}aht20_dev_t;

/* Private variables ---------------------------------------------------------*/

static aht20_dev_t aht20dev;

uint8_t clibrate_arg[] = {AHT20_CMD_CALIBRATION_ARG0, AHT20_CMD_CALIBRATION_ARG1};

uint8_t trigger_arg[] = {AHT20_CMD_TRIGGER_ARG0,AHT20_CMD_TRIGGER_ARG1};

（3）驅(qū)動模塊的入口和出口

module_init(aht20_driver_init);

module_exit(aht20_driver_exit);

（4）ath20_driver_init和aht20_driver_exit實現(xiàn)

static int __init aht20_driver_init(void)

{

pr_info("aht20 driver initn");

return i2c_add_driver(&aht20_driver);

}

static void __exit aht20_driver_exit(void)

{

pr_info("aht20 driver exitn");

i2c_del_driver(&aht20_driver);

}

在入口函數(shù)中調(diào)用了i2c_add_driver函數(shù)，來注冊I2C總線驅(qū)動程序。在出口函數(shù)中調(diào)用了i2c_del_driver函數(shù)，來注銷I2C驅(qū)動程序。

i2c_add_driver函數(shù)原型如下：

int i2c_add_driver(struct i2c_driver *driver);

該函數(shù)接受一個指向struct i2c_driver結(jié)構的指針作為參數(shù)，該結(jié)構包含了驅(qū)動程序的相關信息，例如驅(qū)動程序的名稱、ID表、探測函數(shù)等。函數(shù)返回一個整數(shù)值，表示注冊是否成功。如果成功，返回0；如果失敗，返回一個負數(shù)錯誤代碼。

以下是struct i2c_driver結(jié)構體的常見成員：

driver：這是一個指向struct device_driver結(jié)構的指針，用于描述I2C驅(qū)動程序所屬的設備驅(qū)動程序。

probe：這是一個函數(shù)指針，指向設備探測函數(shù)。當一個設備與I2C總線匹配時，該函數(shù)會被調(diào)用。設備探測函數(shù)負責初始化設備并進行必要的配置。

remove：這是一個函數(shù)指針，指向設備移除函數(shù)。當一個設備從I2C總線上移除時，該函數(shù)會被調(diào)用。設備移除函數(shù)負責釋放設備所占用的資源。

id_table：這是一個指向struct i2c_device_id數(shù)組的指針，用于描述I2C設備的標識信息。驅(qū)動程序可以使用這些標識信息來識別與之匹配的設備。

address_list：這是一個指向unsigned short數(shù)組的指針，用于描述驅(qū)動程序支持的I2C設備地址列表。驅(qū)動程序會使用這些地址來匹配和識別設備。

driver.name：這是一個字符串，表示驅(qū)動程序的名稱。它在設備和驅(qū)動程序之間建立關聯(lián)。

通過調(diào)用i2c_add_driver函數(shù)并傳入正確配置的struct i2c_driver結(jié)構體，可以將I2C總線驅(qū)動程序注冊到Linux內(nèi)核，使其能夠接收和處理I2C設備的相關操作。

（5）i2c_driver類型結(jié)構體定義

struct i2c_driver aht20_driver = {

.probe = aht20_probe,

.remove = aht20_remove,

.id_table = aht20_device_id,

.driver = {

.name = "elf,aht20",

.owner = THIS_MODULE,

.of_match_table = aht20_match_table,

},

};

（6）aht20_match_table實現(xiàn)，用來與設備樹中的compatible匹配

static const struct of_device_id aht20_match_table[] = {

{.compatible = "elf,aht20", },

{ },

};

（7）remove函數(shù)實現(xiàn)，執(zhí)行aht20設備的清理操作

static int aht20_remove(struct i2c_client *client)

{

// 銷毀設備節(jié)點

&nbspdevice_destroy(aht20dev.class, aht20dev.devid);&nbsp

// 銷毀設備類

&nbspclass_destroy(aht20dev.class);&nbsp

// 刪除字符設備

&nbspcdev_del(&aht20dev.cdev);

// 注銷字符設備驅(qū)動程序

&nbspunregister_chrdev_region(aht20dev.devid, DEV_CNT);

&nbspreturn 0;

}

（8）probe函數(shù)實現(xiàn)，此處簡略描述regmap注冊的過程。

static int aht20_probe(struct i2c_client *client, const struct i2c_device_id *id)

{

&nbspint ret = -1;

// 注冊字符設備驅(qū)動程序

&nbspret = alloc_chrdev_region(&aht20dev.devid, 0, DEV_CNT, DEV_NAME);

&nbspif (ret < 0)

&nbsp{

&nbsp&nbspprintk("fail to alloc aht_devn");

&nbsp&nbspgoto alloc_err;

&nbsp}

//初始化字符設備結(jié)構體

&nbspcdev_init(&aht20dev.cdev, &aht20_chr_dev_fops);

//將字符設備添加到內(nèi)核中

&nbspret = cdev_add(&aht20dev.cdev, aht20dev.devid, DEV_CNT);

&nbspif (ret < 0)

&nbsp{

&nbsp&nbspprintk("fail to add cdevn");

&nbsp&nbspgoto add_err;

&nbsp}

// 創(chuàng)建設備類

&nbspaht20dev.class = class_create(THIS_MODULE, DEV_NAME);

// 創(chuàng)建設備節(jié)點并關聯(lián)到設備類

&nbspaht20dev.device = device_create(aht20dev.class, NULL, aht20dev.devid, NULL, DEV_NAME);

&nbspaht20dev.private_data = client;

&nbspaht20_init();

&nbspreturn 0;

add_err:

&nbspunregister_chrdev_region(aht20dev.devid, DEV_CNT);

&nbspprintk("n add_err error! n");

alloc_err:

&nbspreturn -1;

}

probe函數(shù)中實現(xiàn)的就是前面講到的字符設備的注冊流程，注冊完成后調(diào)用aht20_init()函數(shù)，對芯片進行初始化。

（9）定義file_operations類型結(jié)構體：

static struct file_operations aht20_chr_dev_fops =

{

.owner = THIS_MODULE,

.open = aht20_open,

.read = aht20_read,

.release = aht20_release,

};
static int aht20_open(struct inode *inode, struct file *filp)

{

&nbspfilp->private_data = &aht20dev;

return 0;

}

static ssize_t aht20_read(struct file *filp, char __user *buf, size_t cnt, loff_t *off)

{

&nbspfloat temp,humi;

//&nbspuint8_t data[7] = {0};

&nbspuint32_t data[2] = {0};

&nbsplong err = 0;

&nbspfilp->private_data = &aht20dev;

&nbspaht20_get_measure(&data[0]);

&nbsperr = copy_to_user(buf, data, sizeof(data));

return 0;

}

static int aht20_release(struct inode *inode, struct file *filp)

{

return 0;

}

（10）操作函數(shù)的實現(xiàn)：

aht20_read函數(shù)中調(diào)用aht20_get_measuer()函數(shù)讀取溫濕度傳感器中的數(shù)據(jù)，然后通過copy_to_user()函數(shù)將數(shù)據(jù)拷貝到用戶空間。

（11）aht20_get_measuer()函數(shù)定義：

static int aht20_get_measure(uint32_t* RAW)

{

&nbspint retval = 0, i = 0;

&nbspuint8_t data[7] = {0};

&nbspretval = aht20_write_regs(&aht20dev,AHT20_CMD_TRIGGER,trigger_arg,2);

&nbspmsleep(AHT20_MEASURE_TIME);

&nbspaht20_read_data(&aht20dev,data,7);

&nbsp

&nbspfor (i = 0; AHT20_STATUS_BUSY(data[0]) && i < AHT20_MAX_RETRY; i++) {

&nbsp&nbspprintk("AHT20 device busy, retry %d/%d!rn", i, AHT20_MAX_RETRY);

&nbsp&nbspmsleep(AHT20_MEASURE_TIME);

&nbsp&nbspaht20_read_data(&aht20dev,data,7);

}

&nbspif (i >= AHT20_MAX_RETRY) {

printk("AHT20 device always busy!rn");

}

&nbspuint32_t humiRaw = data[1];

humiRaw = (humiRaw << 8) | data[2];

humiRaw = (humiRaw << 4) | ((data[3] & 0xF0) >> 4);

uint32_t tempRaw = data[3] & 0x0F;

tempRaw = (tempRaw << 8) | data[4];

tempRaw = (tempRaw << 8) | data[5];

&nbspRAW[0] = humiRaw;

&nbspRAW[1] = tempRaw;

//&nbspprintk("aht20 humiRAW = %05X, ?tempRAW = %05Xrn", humiRaw, tempRaw);

&nbspreturn 0;

}

aht20_get_measuer()函數(shù)中又調(diào)用了aht20_write_regs()函數(shù)寫寄存器，aht20_read_data()函數(shù)來讀取數(shù)據(jù)。

（12）aht20_write_regs()函數(shù)和aht20_read_data()函數(shù)的定義：

static s32 aht20_write_regs(aht20_dev_t *dev, u8 reg, u8 *buf, u8 len)

{

&nbspu8 byte[256] = {0};

&nbspstruct i2c_msg msg;

&nbspstruct i2c_client *client = (struct i2c_client*)dev->private_data;

&nbspbyte[0] = reg;&nbsp/*!< 寄存器首地址 */

&nbspmemcpy(&byte[1], buf, len);&nbsp/*!< 拷貝數(shù)據(jù) */

&nbsp

&nbspmsg.addr = client->addr;&nbsp/*!< aht20地址 */

&nbspmsg.flags = 0;&nbsp/*!< 標記為寫數(shù)據(jù) */

&nbspmsg.buf = byte;

&nbspmsg.len = len + 1;&nbsp&nbsp/*!< 要寫入數(shù)據(jù)的長度 */&nbsp

&nbsp

&nbspreturn i2c_transfer(client->adapter, &msg, 1);

}

static int aht20_read_data(aht20_dev_t *dev, void *val, int len)

{

&nbspint ret = 0;

&nbspstruct i2c_msg msg[2];

&nbspstruct i2c_client *client = (struct i2c_client*)dev->private_data;

&nbsp/* msg[1]為要讀取數(shù)據(jù) */

&nbspmsg[0].addr = client->addr;&nbsp/*!< aht20地址 */

&nbspmsg[0].flags = I2C_M_RD;&nbsp/*!< 標記為讀取數(shù)據(jù) */

&nbspmsg[0].buf = val;&nbsp/*!< 讀取數(shù)據(jù)的緩沖區(qū) */

&nbspmsg[0].len = len;&nbsp&nbsp/*!< 讀取數(shù)據(jù)的長度 */&nbsp

&nbspreturn i2c_transfer(client->adapter, msg, 1);

}

函數(shù)中都調(diào)用了i2c_transfer()函數(shù)，這是一個用來進行I2C數(shù)據(jù)傳輸的函數(shù)，原型如下：

int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num);

該函數(shù)接受三個參數(shù)：

adap：一個指向struct i2c_adapter結(jié)構的指針，表示要使用的I2C適配器。

msgs：一個指向struct i2c_msg結(jié)構數(shù)組的指針，每個結(jié)構表示一個I2C傳輸消息（包括讀取和寫入操作）。

num：傳輸消息的數(shù)量，即msgs數(shù)組中的元素個數(shù)。

函數(shù)返回一個整數(shù)值，表示傳輸是否成功。如果成功，返回傳輸?shù)南?shù)量；如果失敗，返回一個負數(shù)錯誤代碼。

struct i2c_msg結(jié)構體用于描述一個I2C傳輸消息，定義如下：

struct i2c_msg {

__u16 addr; ??????// 設備地址

__u16 flags; ?????// 消息標志位

__u16 len; ???????// 數(shù)據(jù)長度

__u8 *buf; ???????// 數(shù)據(jù)緩沖區(qū)

};

該結(jié)構包含以下成員：

addr：表示I2C設備的地址。

flags：用于指定消息的標志位，例如讀取或?qū)懭氩僮鳌?/p>

len：指定數(shù)據(jù)緩沖區(qū)的長度。

buf：指向數(shù)據(jù)緩沖區(qū)的指針，用于存儲要傳輸?shù)臄?shù)據(jù)。

通過調(diào)用i2c_transfer函數(shù)，可以將一系列的I2C傳輸消息發(fā)送到指定的I2C設備上，以實現(xiàn)數(shù)據(jù)的讀取和寫入操作。

完整的驅(qū)動elf-aht20.c源碼

#include <linux/init.h>

#include <linux/module.h>

#include <linux/fs.h>

#include <linux/cdev.h>

#include <linux/uaccess.h>

#include <linux/i2c.h>

#include <linux/types.h>

#include <linux/kernel.h>

#include <linux/delay.h>

#include <linux/ide.h>

#include <linux/errno.h>

#include <linux/gpio.h>

#include <asm/mach/map.h>

#include <linux/of.h>

#include <linux/of_address.h>

#include <linux/of_gpio.h>

#include <asm/io.h>

#include <linux/device.h>

#include <linux/platform_device.h>

#include "i2c_aht20.h"

#define DEV_NAME "aht20"

#define DEV_CNT (1)

/* Private typedef -----------------------------------------------------------*/

/* aht20設備結(jié)構體 */

typedef struct {

&nbspdev_t devid;&nbsp&nbsp&nbsp/*!< 設備號 */

&nbspstruct cdev cdev;&nbsp&nbsp/*!< cdev */

&nbspstruct class *class;&nbsp/*!< 類 */

&nbspstruct device *device;&nbsp/*!< 設備 */

&nbspstruct device_node *nd; /*!< 設備節(jié)點 */

&nbspint major;&nbsp&nbsp&nbsp&nbsp/*!< 主設備號 */

&nbspvoid *private_data;&nbsp&nbsp/*!< 私有數(shù)據(jù) */

&nbspunsigned short ir, als, ps;&nbsp/*!< 光傳感數(shù)據(jù) */

}aht20_dev_t;

/* Private variables ---------------------------------------------------------*/

static aht20_dev_t aht20dev;

uint8_t clibrate_arg[] = {AHT20_CMD_CALIBRATION_ARG0, AHT20_CMD_CALIBRATION_ARG1};

uint8_t trigger_arg[] = {AHT20_CMD_TRIGGER_ARG0,AHT20_CMD_TRIGGER_ARG1};

static s32 aht20_write_regs(aht20_dev_t *dev, u8 reg, u8 *buf, u8 len)

{

&nbspu8 byte[256] = {0};

&nbspstruct i2c_msg msg;

&nbspstruct i2c_client *client = (struct i2c_client*)dev->private_data;

&nbspbyte[0] = reg;&nbsp/*!< 寄存器首地址 */

&nbspmemcpy(&byte[1], buf, len);&nbsp/*!< 拷貝數(shù)據(jù) */

&nbsp

&nbspmsg.addr = client->addr;&nbsp/*!< aht20地址 */

&nbspmsg.flags = 0;&nbsp/*!< 標記為寫數(shù)據(jù) */

&nbspmsg.buf = byte;

&nbspmsg.len = len + 1;&nbsp&nbsp/*!< 要寫入數(shù)據(jù)的長度 */&nbsp

&nbsp

&nbspreturn i2c_transfer(client->adapter, &msg, 1);

}

static int aht20_read_regs(aht20_dev_t *dev, u8 reg, void *val, int len)

{

&nbspint ret = 0;

&nbspstruct i2c_msg msg[2];

&nbspstruct i2c_client *client = (struct i2c_client*)dev->private_data;

&nbsp/* msg[0]為發(fā)送要讀取的首地址 */

&nbspmsg[0].addr = client->addr;&nbsp/*!< aht20地址 */

&nbspmsg[0].flags = 0;&nbsp/*!< 標記為發(fā)送數(shù)據(jù) */

&nbspmsg[0].buf = ?&nbsp/*!< 讀取的首地址 */

&nbspmsg[0].len = 1;&nbsp&nbsp/*!< reg長度 */

&nbsp/* msg[1]為要讀取數(shù)據(jù) */

&nbspmsg[1].addr = client->addr;&nbsp/*!< aht20地址 */

&nbspmsg[1].flags = I2C_M_RD;&nbsp/*!< 標記為讀取數(shù)據(jù) */

&nbspmsg[1].buf = val;&nbsp/*!< 讀取數(shù)據(jù)的緩沖區(qū) */

&nbspmsg[1].len = len;&nbsp&nbsp/*!< 讀取數(shù)據(jù)的長度 */&nbsp

&nbspret = i2c_transfer(client->adapter, msg, 2);

&nbspif (ret == 2)&nbspret = 0;

&nbspelse ret = -EREMOTEIO;

&nbspreturn ret;

}

static void aht20_write_reg(aht20_dev_t *dev, u8 reg, u8 data)

{

&nbspu8 buf = 0;

&nbspbuf = data;

&nbspaht20_write_regs(dev, reg, &buf, 1);

}

static unsigned char aht20_read_reg(aht20_dev_t *dev, u8 reg)

{

&nbspu8 data = 0;

&nbspaht20_read_regs(dev, reg, &data, 1);

&nbspreturn data;

#if 0

&nbspstruct i2c_client *client = (struct i2c_client *)dev->private_data;

&nbspreturn i2c_smbus_read_byte_data(client, reg);

#endif

}

static int aht20_read_data(aht20_dev_t *dev, void *val, int len)

{

&nbspint ret = 0;

&nbspstruct i2c_msg msg[2];

&nbspstruct i2c_client *client = (struct i2c_client*)dev->private_data;

&nbsp/* msg[1]為要讀取數(shù)據(jù) */

&nbspmsg[0].addr = client->addr;&nbsp/*!< aht20地址 */

&nbspmsg[0].flags = I2C_M_RD;&nbsp/*!< 標記為讀取數(shù)據(jù) */

&nbspmsg[0].buf = val;&nbsp/*!< 讀取數(shù)據(jù)的緩沖區(qū) */

&nbspmsg[0].len = len;&nbsp&nbsp/*!< 讀取數(shù)據(jù)的長度 */&nbsp

&nbspreturn i2c_transfer(client->adapter, msg, 1);

}

static int aht20_get_measure(uint32_t* RAW)

{

&nbspint retval = 0, i = 0;

&nbspuint8_t data[7] = {0};

&nbspretval = aht20_write_regs(&aht20dev,AHT20_CMD_TRIGGER,trigger_arg,2);

&nbspmsleep(AHT20_MEASURE_TIME);

&nbspaht20_read_data(&aht20dev,data,7);

&nbsp

&nbspfor (i = 0; AHT20_STATUS_BUSY(data[0]) && i < AHT20_MAX_RETRY; i++) {

&nbsp&nbspprintk("AHT20 device busy, retry %d/%d!rn", i, AHT20_MAX_RETRY);

&nbsp&nbspmsleep(AHT20_MEASURE_TIME);

&nbsp&nbspaht20_read_data(&aht20dev,data,7);

}

&nbspif (i >= AHT20_MAX_RETRY) {

printk("AHT20 device always busy!rn");

}

&nbspuint32_t humiRaw = data[1];

humiRaw = (humiRaw << 8) | data[2];

humiRaw = (humiRaw << 4) | ((data[3] & 0xF0) >> 4);

uint32_t tempRaw = data[3] & 0x0F;

tempRaw = (tempRaw << 8) | data[4];

tempRaw = (tempRaw << 8) | data[5];

&nbspRAW[0] = humiRaw;

&nbspRAW[1] = tempRaw;

//&nbspprintk("aht20 humiRAW = %05X, ?tempRAW = %05Xrn", humiRaw, tempRaw);

&nbspreturn 0;

}

/* send reset cmd */

static int aht20_write_reset(aht20_dev_t *dev)

{

&nbspu8 byte[256] = {0};

&nbspstruct i2c_msg msg;

&nbspstruct i2c_client *client = (struct i2c_client*)dev->private_data;

&nbspbyte[0] = AHT20_CMD_RESET;&nbsp/*!< 寄存器首地址 */

&nbspmsg.addr = client->addr;&nbsp/*!< aht20地址 */

&nbspmsg.flags = 0;&nbsp/*!< 標記為寫數(shù)據(jù) */

&nbspmsg.buf = byte;&nbsp/*!< 要寫入的數(shù)據(jù)緩沖區(qū) */

&nbspmsg.len = 1;&nbsp&nbsp/*!< 要寫入數(shù)據(jù)的長度 */&nbsp

&nbsp

&nbspreturn i2c_transfer(client->adapter, &msg, 1);

}

static int aht20_init(void)

{

&nbspunsigned char status;

&nbspint retval;

&nbspfloat temp, humi;

&nbspuint8_t RAW[7];

&nbspstatus = aht20_read_reg(&aht20dev, AHT20_CMD_STATUS);

&nbspif (AHT20_STATUS_BUSY(status) || !AHT20_STATUS_CALI(status)) {

&nbsp&nbspretval = aht20_write_reset(&aht20dev);

&nbsp&nbspmsleep(AHT20_STARTUP_TIME);

&nbsp&nbspretval = aht20_write_regs(&aht20dev,AHT20_CMD_CALIBRATION,clibrate_arg,2);

&nbsp&nbspmsleep(AHT20_CALIBRATION_TIME);

&nbsp&nbspreturn retval;

}

&nbspaht20_get_measure(&RAW[0]);

}

static int aht20_open(struct inode *inode, struct file *filp)

{

&nbspfilp->private_data = &aht20dev;

return 0;

}

static ssize_t aht20_read(struct file *filp, char __user *buf, size_t cnt, loff_t *off)

{

&nbspfloat temp,humi;

//&nbspuint8_t data[7] = {0};

&nbspuint32_t data[2] = {0};

&nbsplong err = 0;

&nbspfilp->private_data = &aht20dev;

&nbspaht20_get_measure(&data[0]);

&nbsperr = copy_to_user(buf, data, sizeof(data));

return 0;

}

static int aht20_release(struct inode *inode, struct file *filp)

{

return 0;

}

static struct file_operations aht20_chr_dev_fops =

{

.owner = THIS_MODULE,

.open = aht20_open,

.read = aht20_read,

.release = aht20_release,

};

static int aht20_probe(struct i2c_client *client, const struct i2c_device_id *id)

{

&nbspint ret = -1;

&nbspret = alloc_chrdev_region(&aht20dev.devid, 0, DEV_CNT, DEV_NAME);

&nbspif (ret < 0)

&nbsp{

&nbsp&nbspprintk("fail to alloc aht_devn");

&nbsp&nbspgoto alloc_err;

&nbsp}

//&nbspaht20_chr_dev.owner = THIS_MODULE;

&nbspcdev_init(&aht20dev.cdev, &aht20_chr_dev_fops);

&nbspret = cdev_add(&aht20dev.cdev, aht20dev.devid, DEV_CNT);

&nbspif (ret < 0)

&nbsp{

&nbsp&nbspprintk("fail to add cdevn");

&nbsp&nbspgoto add_err;

&nbsp}

&nbspaht20dev.class = class_create(THIS_MODULE, DEV_NAME);

&nbspaht20dev.device = device_create(aht20dev.class, NULL, aht20dev.devid, NULL, DEV_NAME);

&nbspaht20dev.private_data = client;

&nbspaht20_init();

&nbspreturn 0;

add_err:

&nbspunregister_chrdev_region(aht20dev.devid, DEV_CNT);

&nbspprintk("n add_err error! n");

alloc_err:

&nbspreturn -1;

}

static int aht20_remove(struct i2c_client *client)

{

&nbspdevice_destroy(aht20dev.class, aht20dev.devid);&nbsp

&nbspclass_destroy(aht20dev.class);&nbsp

&nbspcdev_del(&aht20dev.cdev);

&nbspunregister_chrdev_region(aht20dev.devid, DEV_CNT);

&nbspreturn 0;

}

static const struct i2c_device_id aht20_device_id[] = {

{"elf,aht20", 0},

{ }

};

/*定義設備樹匹配表*/

static const struct of_device_id aht20_match_table[] = {

{.compatible = "elf,aht20", },

{ },

};

/*定義i2c設備結(jié)構體*/

struct i2c_driver aht20_driver = {

.probe = aht20_probe,

.remove = aht20_remove,

.id_table = aht20_device_id,

.driver = {

.name = "elf,aht20",

.owner = THIS_MODULE,

.of_match_table = aht20_match_table,

},

};

static int __init aht20_driver_init(void)

{

pr_info("aht20 driver initn");

return i2c_add_driver(&aht20_driver);

}

static void __exit aht20_driver_exit(void)

{

pr_info("aht20 driver exitn");

i2c_del_driver(&aht20_driver);

}

module_init(aht20_driver_init);

module_exit(aht20_driver_exit);

MODULE_LICENSE("GPL");

MODULE_AUTHOR("bkxr@outlook.com");

MODULE_DESCRIPTION("aht20 sensor driver");

編譯

復制7.7.3驅(qū)動中的Makefile文件，將其中的platform_led.o修改為elf-aht20.o，效果如下：

. /opt/fsl-imx-x11/4.1.15-2.0.0/environment-setup-cortexa7hf-neon-poky-linux-gnueabi

elf@ubuntu:~/work/test/07_I2C驅(qū)動-aht20/aht20$ make

將編譯生成的elf-aht20.ko模塊拷貝到開發(fā)板。

編寫測試應用源碼aht20_app.c

測試源碼中循環(huán)讀取驅(qū)動傳到用戶空間的數(shù)據(jù)：

#include "stdio.h"

#include "unistd.h"

#include "sys/types.h"

#include "sys/stat.h"

#include "sys/ioctl.h"

#include "fcntl.h"

#include "stdlib.h"

#include "string.h"

#include <poll.h>

#include <sys/select.h>

#include <sys/time.h>

#include <signal.h>

#include <fcntl.h>

#define AHT20_DEV "/dev/aht20"

int main(int argc, char *argv[])

{

&nbspint fd;

&nbspunsigned int databuf[2];

&nbspint c1,t1;

&nbspfloat hum,temp;

&nbspint ret = 0;

&nbspfd = open(AHT20_DEV, O_RDWR);

&nbspif(fd < 0) {

&nbsp&nbspprintf("can't open file %srn", AHT20_DEV);

&nbsp&nbspreturn -1;

&nbsp}

&nbspwhile (1) {

&nbsp&nbspret = read(fd, databuf, sizeof(databuf));

&nbsp&nbspif(ret == 0) { &nbsp&nbsp&nbsp/* ?????? */

&nbsp&nbsp?c1 = databuf[0]*1000/1024/1024; ?//

&nbsp&nbsp?t1 = databuf[1] *200*10/1024/1024-500;

&nbsp&nbsp?hum = (float)c1/10.0;

&nbsp&nbsp?temp = (float)t1/10.0;

&nbsp&nbspprintf("hum = %0.2f temp = %0.2f rn",hum,temp);

&nbsp&nbspusleep(500000);

&nbsp&nbsp}

&nbsp}

&nbspclose(fd);&nbsp

&nbspreturn 0;

}

編譯應用

. /opt/fsl-imx-x11/4.1.15-2.0.0/environment-setup-cortexa7hf-neon-poky-linux-gnueabi

elf@ubuntu:~/work/test/07_I2C驅(qū)動-aht20/aht20_app$?$CC aht20_app.c -o aht20_app

將編譯好的測試應用拷貝到開發(fā)板中。

測試

root@ELF1:~# insmod elf-aht20.ko

aht20 driver init

root@ELF1:~# ./aht20_app

hum = 45.60 temp = 30.60

hum = 45.60 temp = 30.60

hum = 45.70 temp = 30.60

hum = 45.70 temp = 30.60

hum = 45.60 temp = 30.60

root@ELF1:~# rmmod elf-aht20.ko

aht20 driver exit

相關推薦