drivers/bmx055: use i2c_acquire and _release

add missing i2c_acquire and i2c_release calls to properly guard
    i2c read and write operations.

drivers/bmx055/bmx055.c

@@ -60,36 +60,44 @@ int bmx055_init(bmx055_t *dev, const bmx055_params_t *params)
      * and try to read magnetometer id
      * NOTE: this is necessary because the module id is 0x00 in suspend mode
      */
+    i2c_acquire(BUS);
     if (i2c_write_reg(BUS, ADDR_MAG, REG_MAG_PWRCTRL, BIT_MAG_PWRCTRL_VAL, 0x0) < 0) {
         DEBUG("[bmx055] error: no connection to magnetometer\n");
+        i2c_release(BUS);
         return BMX055_NODEV;
     }
     if (i2c_read_reg(BUS, ADDR_MAG, REG_MAG_CHIPID, &tmp, 0x0) < 0) {
         DEBUG("[bmx055] error: no connection to magnetometer\n");
+        i2c_release(BUS);
         return BMX055_NODEV;
     }
     if (tmp != REG_MAG_CHIPID_VAL) {
         DEBUG("[bmx055] error: no connection to magnetometer\n");
+        i2c_release(BUS);
         return BMX055_NODEV;
     }
 
     /* try to read accelerometer id */
     if (i2c_read_reg(BUS, ADDR_ACC, REG_ACC_CHIPID, &tmp, 0x0) < 0) {
         DEBUG("[bmx055] error: no connection to accelerometer\n");
+        i2c_release(BUS);
         return BMX055_NODEV;
     }
     if (tmp != REG_ACC_CHIPID_VAL) {
         DEBUG("[bmx055] error: no connection to accelerometer\n");
+        i2c_release(BUS);
         return BMX055_NODEV;
     }
 
     /* try to read gyroscope id */
     if (i2c_read_reg(BUS, ADDR_GYRO, REG_GYRO_CHIPID, &tmp, 0x0) < 0) {
         DEBUG("[bmx055] error: no connection to gyroscope\n");
+        i2c_release(BUS);
         return BMX055_NODEV;
     }
     if (tmp != REG_GYRO_CHIPID_VAL) {
         DEBUG("[bmx055] error: no connection to gyroscope\n");
+        i2c_release(BUS);
         return BMX055_NODEV;
     }
 
@@ -100,6 +108,7 @@ int bmx055_init(bmx055_t *dev, const bmx055_params_t *params)
      */
     if (i2c_write_reg(BUS, ADDR_MAG, REG_MAG_OPMODE, (dev->p.mag_rate << 3), 0x0) < 0) {
         DEBUG("[bmx055] error: setting magnetometer opmode\n");
+        i2c_release(BUS);
         return BMX055_NOWRITE;
     }
 
@@ -109,18 +118,21 @@ int bmx055_init(bmx055_t *dev, const bmx055_params_t *params)
      */
     if (i2c_write_reg(BUS, ADDR_ACC, 0x14, 0xB6, 0x0) < 0) {
         DEBUG("[bmx055] erro: setting accelerometer opmode\n");
+        i2c_release(BUS);
         return BMX055_NOWRITE;
     }
 
     /* setting acc range */
     if (i2c_write_reg(BUS, ADDR_ACC, REG_ACC_RANGE, acc_ranges[dev->p.acc_range], 0x0) < 0) {
         DEBUG("[bmx055] error: setting accelerometer range\n");
+        i2c_release(BUS);
         return BMX055_NOWRITE;
     }
 
     /* enable acc shadowing */
     if (i2c_write_reg(BUS, ADDR_ACC, REG_ACC_SHDW, REG_ACC_SHDW_ENABLE, 0x0) < 0) {
         DEBUG("[bmx055] error: writing accelerometer shadowing bit\n");
+        i2c_release(BUS);
         return BMX055_NOWRITE;
     }
 
@@ -133,21 +145,25 @@ int bmx055_init(bmx055_t *dev, const bmx055_params_t *params)
      */
     if (i2c_write_reg(BUS, ADDR_GYRO, REG_GYRO_PWRMD, REG_GYRO_PWRMD_NORM, 0x0) < 0) {
         DEBUG("[bmx055] error: setting gyroscope opmode\n");
+        i2c_release(BUS);
         return BMX055_NOWRITE;
     }
 
     /* setting gyro scale */
     if (i2c_write_reg(BUS, ADDR_GYRO, REG_GYRO_SCALE, dev->p.gyro_scale, 0x0) < 0) {
         DEBUG("[bmx055] error: setting gyroscope scale\n");
+        i2c_release(BUS);
         return BMX055_NOWRITE;
     }
 
     /* enable gyro shadowing */
     if (i2c_write_reg(BUS, ADDR_GYRO, REG_GYRO_SHDW, REG_GYRO_SHDW_EN, 0x0) < 0) {
         DEBUG("[bmx055] error: setting gyroscope shadowing bit\n");
+        i2c_release(BUS);
         return BMX055_NOWRITE;
     }
 
+    i2c_release(BUS);
     return BMX055_OK;
 }
 
@@ -158,10 +174,13 @@ int bmx055_mag_read(const bmx055_t *dev, int16_t *data)
     uint8_t tmp[7];
 
     /* reading magnetometer data */
+    i2c_acquire(BUS);
     if (i2c_read_regs(BUS, ADDR_MAG, REG_MAG_DATA, &tmp, 7, 0x0) < 0) {
         DEBUG("[bmx055] error: reading magnetometer data\n");
+        i2c_release(BUS);
         return BMX055_NOREAD;
     }
+    i2c_release(BUS);
 
     /* checking if new data was available */
     if ((tmp[6] & BIT_MAG_DATARDY) != 1) {
@@ -183,10 +202,13 @@ int bmx055_acc_read(const bmx055_t *dev, int16_t *data)
     uint8_t tmp[7];
 
     /* reading accelerometer data */
+    i2c_acquire(BUS);
     if (i2c_read_regs(BUS, ADDR_ACC, REG_ACC_DATA, &tmp, 7, 0x0) < 0) {
         DEBUG("[bmx055] error: reading accelerometer data\n");
+        i2c_release(BUS);
         return BMX055_NOREAD;
     }
+    i2c_release(BUS);
 
     if (((tmp[0] & 1) == 0) || ((tmp[2] & 1) == 0) || ((tmp[4] & 1) == 0)) {
         DEBUG("[bmx055] error: no acceleration data ready\n");
@@ -215,10 +237,13 @@ int bmx055_gyro_read(const bmx055_t *dev, int16_t *data)
     scale = (GYRO_2000_DPS / pow(2, dev->p.gyro_scale));
 
     /* reading gyroscope data */
+    i2c_acquire(BUS);
     if (i2c_read_regs(BUS, ADDR_GYRO, REG_GYRO_DATA, &tmp, 6, 0x0) < 0) {
         DEBUG("[bmx055] error: reading gyroscope data\n");
+        i2c_release(BUS);
         return BMX055_NOREAD;
     }
+    i2c_release(BUS);
 
     for (int i = 0; i < 3; i++) {
         /* shifting and casting register data */