u8 datah,datal;
u16 val;
i2c_read_reg(regh,&datah,1);
i2c_read_reg(regl,&datal,1);
val = (datah & 0x00ff) << 8;
val |= datal & 0xff;
return val;
}
static s32 BMP180_Read32Reg(u8 regh,u8 regm,u8 regl){
u8 datah,datam,datal;
s32 val;
i2c_read_reg(regh,&datah,1);
i2c_read_reg(regm,&datam,1);
i2c_read_reg(regl,&datal,1);
val = (datah & 0x0000ff) << 16;
val |= (datam & 0x0000ff) << 8;
val |= (datal & 0x0000ff) ;
return val;
}
static void BMP180_Init(void){
BMP180_CalcParam_t* pBMP180_CP = &BMP180_CalcParams;
pBMP180_CP->AC1 = BMP180_Reads16Reg(0xaa,0xab);
pBMP180_CP->AC2 = BMP180_Reads16Reg(0xac,0xad);
pBMP180_CP->AC3 = BMP180_Reads16Reg(0xae,0xaf);
pBMP180_CP->AC4 = BMP180_Readu16Reg(0xb0,0xb1);
pBMP180_CP->AC5 = BMP180_Readu16Reg(0xb2,0xb3);
pBMP180_CP->AC6 = BMP180_Readu16Reg(0xb4,0xb4);
pBMP180_CP->B1 = BMP180_Reads16Reg(0xb6,0xb7);
pBMP180_CP->B2 = BMP180_Reads16Reg(0xb8,0xb9);
pBMP180_CP->MB = BMP180_Reads16Reg(0xba,0xbb);
pBMP180_CP->MC = BMP180_Reads16Reg(0xbc,0xbd);
pBMP180_CP->MD = BMP180_Reads16Reg(0xbe,0xbf);
}
static void BMP180_ReadT_P(s32* T,s32* P){
BMP180_CalcParam_t* pBMP180_CP = &BMP180_CalcParams;
u8 data = 0x2e;
s32 UT,X1,X2,X3,B3,B6,UP,p;
u32 B4,B7;
i2c_write_reg(0xf4,&data,1);
mdelay(20);
UT = BMP180_Read32Reg(0xf6,0xf7,0xf8) >> 8;
X1 = (UT-pBMP180_CP->AC6)* pBMP180_CP->AC5 >> 15;
X2 = (pBMP180_CP->MC << 11) / (X1 + pBMP180_CP->MD);
*T = (X1 + X2 +8) >> 4 ;
data = 0x34;
i2c_write_reg(0xf4,&data,1);
mdelay(20);
UP = BMP180_Read32Reg(0xf6,0xf7,0xf8) >> 8;
B6 = X1 + X2 - 4000;
X1 = (B6 * B6 >> 12) * pBMP180_CP->B2 >> 11;
X2 = pBMP180_CP->AC2 * B6 >> 11;
X3 = X1 + X2;
B3 = (((pBMP180_CP->AC1 << 2) + X3) + 2) >> 2;
X1 = pBMP180_CP->AC3 * B6 >> 13;
X2 = (B6 * B6 >> 12) * pBMP180_CP->B1 >> 16;
X3 = (X1 + X2 + 2) >> 2;
B4 = pBMP180_CP->AC4 * (u32)(X3 + 32768) >> 15;
B7 = ((u32)UP - B3) * 50000;
if(B7 < 0x80000000){
p = (B7 << 1) / B4;
}else{
p = B7/B4 << 1;
}
X1 = (p >> 8) * (p >> 8);
X1 = (X1 * 3038) >> 16;
X2 = (-7375 * p) >> 16;
p = p + ((X1 + X2 + 3791) >> 4);
*P = p;
}
int misc_open (struct inode *inode, struct file *file){
printk("misc_open..\n");
BMP180_Init();
return 0;
}
int misc_release (struct inode *inode, struct file *file){
printk("misc_release..\n");
return 0;
}
ssize_t misc_read (struct file *file, char __user *ubuf, size_t size, loff_t *of){
int ret;
BMP180_Result BMP180_Result;
BMP180_ReadT_P(&BMP180_Result.T,&BMP180_Result.P);
ret = copy_to_user(ubuf,&BMP180_Result,sizeof(BMP180_Result));
if(ret!=0){
printk("copy_to_user err..\n");
return -1;
}
return sizeof(BMP180_Result);
}
static const struct file_operations misc_fops={
.owner = THIS_MODULE,
.open = misc_open,
.release = misc_release,
.read = misc_read,
};
static struct miscdevice misc_test={
.minor = MISC_DYNAMIC_MINOR,
.name = "BMP180",
.fops = &misc_fops
};
static int BMP180_i2c_probe(struct i2c_client *client, const struct i2c_device_id *id){
int ret;
fxs_i2c_client = client;
ret = misc_register(&misc_test);
if(ret<0){
printk("misc_register err..\n");
return -1;
}
printk("i2c probe success..\n");
return 0;
}
static int BMP180_i2c_remove(struct i2c_client *client){
misc_deregister(&misc_test);
return 0;
}
static const struct i2c_device_id id_BMP180_i2c_driver[] = {
{"BMP180",},
{}
};
static const struct of_device_id of_BMP180_i2c_driver[] = {
{.compatible = "BMP180",},
{},
};
static struct i2c_driver BMP180_i2c_driver = {
.driver = {
.owner = THIS_MODULE,
.name = "BMP180",
.of_match_table = of_BMP180_i2c_driver,
},
.probe = BMP180_i2c_probe,
.remove = BMP180_i2c_remove,
.id_table = id_BMP180_i2c_driver,
};
static int __init i2c_init(void){
int ret ;
ret = i2c_add_driver(&BMP180_i2c_driver);
if(ret < 0){
printk("i2c_add_driver error..\n");
return ret;
}
printk("i2c_init..\n");
return 0;
}
static void __exit i2c_exit(void){
i2c_del_driver(&BMP180_i2c_driver);
printk("i2c_exit..\n");
}
module_init(i2c_init);
module_exit(i2c_exit);
MODULE_LICENSE("GPL");
1. Run the above command to compile the driver make will get the .ko file
2. Copy the .ko file to DEBIX, run the command sudo insmod BMP180.ko
3. Run the command sudo dmesg | tail -2 , check the driver print information:
4. You can see that the probe function matches the device tree successfully.
