AP_HAL_PX4: embed PX4_I2C object into I2CDevice

Otherwise we would destroy PX4_I2C object after returning from
I2CDeviceManager::get_device(). Since this implementation is very
simple, just make PX4_I2C as an internal class and embed it into the
I2CDevice object.

libraries/AP_HAL_PX4/I2CDevice.cpp

@@ -4,26 +4,29 @@
 
 namespace PX4 {
 
-class PX4_I2C : public device::I2C {
-public:
-    PX4_I2C(uint8_t bus);
-    bool do_transfer(uint8_t address, const uint8_t *send, uint32_t send_len,
-                     uint8_t *recv, uint32_t recv_len);
-};
-
-PX4_I2C::PX4_I2C(uint8_t bus) :
-    I2C("AP_I2C", "/dev/api2c", bus, 0, 400000UL)
+I2CDevice::PX4_I2C::PX4_I2C(uint8_t bus)
+    : I2C("AP_I2C", "/dev/api2c", bus, 0, 400000UL)
 {
     init();
 }
 
-bool PX4_I2C::do_transfer(uint8_t address, const uint8_t *send, uint32_t send_len,
-                          uint8_t *recv, uint32_t recv_len)
+bool I2CDevice::PX4_I2C::do_transfer(uint8_t address, const uint8_t *send, uint32_t send_len,
+                                     uint8_t *recv, uint32_t recv_len)
 {
     set_address(address);
     return transfer(send, send_len, recv, recv_len) == OK;
 }
 
+I2CDevice::I2CDevice(uint8_t bus, uint8_t address)
+    : _device(bus)
+    , _address(address)
+{
+}
+
+I2CDevice::~I2CDevice()
+{
+}
+
 bool I2CDevice::transfer(const uint8_t *send, uint32_t send_len,
                          uint8_t *recv, uint32_t recv_len)
 {
@@ -54,10 +57,6 @@ AP_HAL::Semaphore *I2CDevice::get_semaphore()
     return &semaphore;
 }
 
-I2CDevice::~I2CDevice()
-{
-}
-
 I2CDeviceManager::I2CDeviceManager()
 {
 }
@@ -65,9 +64,8 @@ I2CDeviceManager::I2CDeviceManager()
 AP_HAL::OwnPtr<AP_HAL::I2CDevice>
 I2CDeviceManager::get_device(uint8_t bus, uint8_t address)
 {
-    AP_HAL::OwnPtr<PX4_I2C> i2c { new PX4_I2C(bus) };
-    auto dev = AP_HAL::OwnPtr<AP_HAL::I2CDevice>(new I2CDevice(*i2c, address));
-
+    auto dev = AP_HAL::OwnPtr<AP_HAL::I2CDevice>(new I2CDevice(bus, address));
     return dev;
 }
+
 }

libraries/AP_HAL_PX4/I2CDevice.h

@@ -21,11 +21,7 @@ public:
     }
 
     /* AP_HAL::I2CDevice implementation */
-    I2CDevice(PX4_I2C &device, uint8_t address)
-        : _device(device)
-        , _address(address)
-    {
-    }
+    I2CDevice(uint8_t bus, uint8_t address);
 
     ~I2CDevice();
 
@@ -61,7 +57,14 @@ public:
     int get_fd() override;
 
 protected:
-    PX4_I2C &_device;
+    class PX4_I2C : public device::I2C {
+    public:
+        PX4_I2C(uint8_t bus);
+        bool do_transfer(uint8_t address, const uint8_t *send, uint32_t send_len,
+                         uint8_t *recv, uint32_t recv_len);
+    };
+
+    PX4_I2C _device;
     uint8_t _address;
     uint8_t _retries = 0;