STM32MP157 | 基于 Linux I2C 驱动读ap3216c传感器
一、ap3216c传感器简介
AP3216C是一个集成的ALS和PS模块，包括一个数字环境光传感器[ALS]，一个接近传感器[PS]和一个红外LED在单个封装中。
特性：
- I2C 接口 (FS 模式 @ 400k Hz)
- 模式选择: ALS, PS+IR, ALS+PS+IR, PD, ALS once, SW Reset, PS+IR
- 工作范围 (-30°C to +80°C)
1.ap3216c的常用寄存器列表如下：
2. 开发板原理图
二、 添加设备树的节点
1.设置引脚
首先设置I2C1引脚的复用功能，找到 pinctrl_i2c1 节点：
vi stm32mp15-pinctrl.dtsi
2. 找出控制器的设备树
stm32mp151.dtsi
i2c1: i2c@40012000 {
compatible = "st,stm32mp15-i2c"; //这个是和i2c控制器驱动完成匹配
reg = <0x40012000 0x400>; //控制器的地址和长度
interrupt-names = "event", "error";
interrupts-extended = <&exti 21 IRQ_TYPE_LEVEL_HIGH>,
<&intc GIC_SPI 32 IRQ_TYPE_LEVEL_HIGH>;
clocks = <&rcc I2C1_K>;
resets = <&rcc I2C1_R>;
#address-cells = <1>; //修饰子节点地址的个数
#size-cells = <0>; //修饰子节点长度的个数
dmas = <&dmamux1 33 0x400 0x80000001>,//dam内存直取，可以把数据直接从一个地址搬移到另一个地址
<&dmamux1 34 0x400 0x80000001>;
dma-names = "rx", "tx";
power-domains = <&pd_core>;
st,syscfg-fmp = <&syscfg 0x4 0x1>;
wakeup-source;
i2c-analog-filter;
status = "disabled"; //控制器没有使能
};
3. 根据内核帮助文档编写自己的设备树
/home/linux/linux-5.10.61/Documentation/devicetree/bindings/i2c/
&i2c1{//第0个成员工作状态，第1个休眠状态
pinctrl-names = "default", "sleep";//这个就是列表
pinctrl-0 = <&i2c1_pins_b>;//pinctrl-0 代表列表中第0个成员//i2c1_pins_b代表管脚复用
pinctrl-1 = <&i2c1_sleep_pins_b>;//pinctrl-1 代表列表中第1个成员
i2c-scl-rising-time-ns = <100>;//上升沿时间毫秒
i2c-scl-falling-time-ns = <7>;//下降沿时间
status = "okay"; //使能
/delete-property/dmas; //删除dma属性
/delete-property/dma-names;
si7006@40{ //添加的设备树节点
compatible = "st,si7006";
reg = <0x40>;//从机地址
};
ap3216c@1e{
comptible = "st,ap3216c";
reg = <0x1e>
};
};
4. 重新编译设备树
make dtbs
重启开发板
安装驱动
三. 编写si7006设备驱动
1.先搭个I2C设备驱动框架
#include 2. 写个Makefile编译一下：
ifeq ($(arch),arm)
KERNELDIR :=/home/linux/linux-5.10.61
CROSS_COMPILE ?=arm-linux-gnueabihf-
else
KERNELDIR :=/lib/modules/$(shell uname -r)/build
CROSS_COMPILE ?=
endif
modname ?=
PWD :=$(shell pwd)
CC :=$(CROSS_COMPILE)gcc
all:
make -C $(KERNELDIR) M=$(PWD) modules
# $(CC) test.c -o test
clean:
make -C $(KERNELDIR) M=$(PWD) clean
# rm test
install:
cp *.ko ~/nfs/rootfs/
# cp test ~/nfs/rootfs/
help:
echo "make arch = arm or x86 modname= dirvers file name"
obj-m:=$(modname).o
linux@ubuntu:~/linu/driver/csdn/ap3216c$ make arch=arm modname=ap3216c
3. 再写字符设备驱动框架
int ap3216c_open(struct inode *inode, struct file *file)
{
printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
return 0;
}
ssize_t ap3216c_read(struct file *file, char __user *ubuf, size_t size, loff_t *loff)
{
return size;
}
ssize_t ap3216c_write(struct file *file, const char __user *ubuf, size_t size, loff_t *loff)
{
return size;
}
int ap3216c_close(struct inode *inode, struct file *file)
{
printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
return 0;
}
const struct file_operations fops = {
.open = ap3216c_open,
.read = ap3216c_read,
.write = ap3216c_write,
.release = ap3216c_close,
};
int ap3216c_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
int ret;
gclient = client;
// 1.分配对象
cdev = cdev_alloc();
if (cdev == NULL)
{
printk("alloc memory failed\n");
ret = -ENOMEM;
goto ERR1;
}
// 2.初始化对象
cdev_init(cdev, &fops);
// 3.申请设备号
if (major > 0)
{
ret = register_chrdev_region(MKDEV(major, minor), count, CNAME);
if (ret != 0)
{
printk("static:alloc device number failed!\n");
goto ERR2;
}
}
else if (major == 0)
{
ret = alloc_chrdev_region(&devno, 0, 1, CNAME);
if (ret != 0)
{
printk("dynamic:alloc device number failed!\n");
goto ERR2;
}
major = MAJOR(devno);
minor = MINOR(devno);
}
// 4.注册对象
ret = cdev_add(cdev, MKDEV(major, minor), count);
if (ret)
{
printk("add cdev failed\n");
goto ERR3;
}
// 5.向上层提交目录的信息
cls = class_create(THIS_MODULE, "hello");
if (IS_ERR(cls))
{
printk("create class failed\n");
ret = PTR_ERR(cls);
goto ERR4;
}
// 6.向上层提交设备的信息
dev = device_create(cls, NULL, MKDEV(major, minor), NULL, CNAME);
if (IS_ERR(dev))
{
printk("create device failed\n");
ret = PTR_ERR(dev);
goto ERR5;
}
return 0;
ERR5:
class_destroy(cls);
ERR4:
cdev_del(cdev);
ERR3:
unregister_chrdev_region(MKDEV(major, minor), count);
ERR2:
kfree(cdev);
ERR1:
return ret;
}
int ap3216c_remove(struct i2c_client *client)
{
device_destroy(cls,MKDEV(major,minor));
class_destroy(cls);
cdev_del(cdev);
unregister_chrdev_region(MKDEV(major, minor), count);
kfree(cdev);
printk("%s:%d\n", __func__, __LINE__);
return 0;
}
//通过设备树的形式匹配进入probe函数
const struct of_device_id oftable[] = {
{
.compatible = "st,ap3216c",
},
{},
};
//支持热插拔
MODULE_DEVICE_TABLE(of, oftable);
struct i2c_driver ap3216c = {
.probe = ap3216c_probe,
.remove = ap3216c_remove,
.driver = {
.name = "hello",
.of_match_table = oftable,
}};
module_i2c_driver(ap3216c);
MODULE_LICENSE("GPL");
4.封装i2c操作代码
全局变量中添加 i2c_client 成员：
struct i2c_client *gclient;
在ap3216c_probe函数中添加
gclient = client;//获取从机设备信息结构体
ret = ap3216c_board_init();//驱动加载时进行硬件的初始化
if (ret < 0)
printk("ap3216c_board_init fail\n");
（1）ap316c写寄存器时序如下
int ap3216c_write_reg(uint8_t reg, uint8_t val) //这是一个无符号的char
{
int ret;
struct i2c_msg msg;
uint8_t send_buf[2];
send_buf[0] = reg;
send_buf[1] = val;
msg.addr = gclient->addr;
msg.flags = 0;
msg.len = 2;
msg.buf = send_buf;
ret = i2c_transfer(gclient->adapter, &msg, 1);
if (ret != 1)
{
printk("i2c read serial or firmware error\n");
return -EAGAIN;
}
return 0;
}
（2）ap316c读寄存器时序如下
int ap3216c_board_read_data(void)
{
uint8_t low_val, high_val;
// IR红外led
ap3216c_read_reg(0x0A, &low_val);
ap3216c_read_reg(0x0B, &high_val);
if (low_val & 0x80)
{
data.ir = 0;
}
else
{
data.ir = ((uint16_t)high_val << 2 | (low_val & 0x03));
}
// ALS环境光传感器
ap3216c_read_reg(0x0C, &low_val);
ap3216c_read_reg(0x0D, &high_val);
data.als = ((uint16_t)high_val << 8) | low_val;
// ps接近光传感器
ap3216c_read_reg(0x0E, &low_val);
ap3216c_read_reg(0x0F, &high_val);
if (low_val & 0x40)
{
data.ps = 0;
}
else
{
data.ps = ((uint16_t)(high_val & 0x3F) << 4) | (low_val & 0x0F);
}
return 0;
}
5.ap3216c的初始化
//ap3216c的初始化
int ap3216c_board_init(void)
{
int ret;
uint8_t val;
// 设置AP3216C系统模式，软复位
ret = ap3216c_write_reg(0x00, 0x04);
if (ret < 0)
{
printk("ap3216 soft reset fail\n");
return -1;
}
// 软复位后至少等待10ms
mdelay(150);
// 设置AP3216C系统模式，ALS+PS+IR单次模式
ret = ap3216c_write_reg(0x00, 0x03);
if (ret < 0)
{
printk("ap3216 activate fail\n");
return -1;
}
mdelay(150);
// 读模式寄存器，确认模式写入成功
ret = ap3216c_read_reg(0x00, &val);
if (ret < 0)
{
printk("ap3216 read mode fail\n");
return -1;
}
printk("ap3216 mode :%d\n", val);
return 0;
}
6.ap3216c读取数据
int ap3216c_board_read_data(void)
{
uint8_t low_val, high_val;
// IR红外led
ap3216c_read_reg(0x0A, &low_val);
ap3216c_read_reg(0x0B, &high_val);
if (low_val & 0x80)
{
data.ir = 0;
}
else
{
data.ir = ((uint16_t)high_val << 2 | (low_val & 0x03));
}
// ALS环境光传感器
ap3216c_read_reg(0x0C, &low_val);
ap3216c_read_reg(0x0D, &high_val);
data.als = ((uint16_t)high_val << 8) | low_val;
// ps接近光传感器
ap3216c_read_reg(0x0E, &low_val);
ap3216c_read_reg(0x0F, &high_val);
if (low_val & 0x40)
{
data.ps = 0;
}
else
{
data.ps = ((uint16_t)(high_val & 0x3F) << 4) | (low_val & 0x0F);
}
return 0;
}
7.字符设备驱动的实现
头文件引入
#include open
int ap3216c_open(struct inode *inode, struct file *file)
{
printk("%s:%d\n", __func__, __LINE__);
return 0;
}
read
ssize_t ap3216c_read(struct file *file, char __user *ubuf, size_t size, loff_t *loff)
{
uint16_t rdata[3];
int ret;
ap3216c_board_read_data();
rdata[0] = data.ir;
rdata[1] = data.als;
rdata[2] = data.ps;
//printk("ir:%d ,als:%d, ps:%d\n", rdata[0], rdata[1], rdata[2]);
ret = copy_to_user(ubuf, rdata, sizeof(rdata));
if (ret)
{
printk("copy data to user error\n");
return -EIO;
}
return size;
}
write
ssize_t ap3216c_write(struct file *file, const char __user *ubuf, size_t size, loff_t *loff)
{
return size;
}
close
int ap3216c_close(struct inode *inode, struct file *file)
{
printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
return 0;
}
四、测试驱动模块
1.加载驱动,查看驱动
2.编写app测试程序
#include 
成功读取读到红外，环境光，接近传感器数据