Add a driver for the Analog Devices ADIS16448 IMU (#8301)

src/drivers/device/nuttx/SPI.cpp

@@ -181,4 +181,56 @@ SPI::_transfer(uint8_t *send, uint8_t *recv, unsigned len)
 	return OK;
 }
 
+int
+SPI::transferhword(uint16_t *send, uint16_t *recv, unsigned len)
+{
+	int result;
+
+	if ((send == nullptr) && (recv == nullptr)) {
+		return -EINVAL;
+	}
+
+	LockMode mode = up_interrupt_context() ? LOCK_NONE : locking_mode;
+
+	/* lock the bus as required */
+	switch (mode) {
+	default:
+	case LOCK_PREEMPTION: {
+			irqstate_t state = px4_enter_critical_section();
+			result = _transferhword(send, recv, len);
+			px4_leave_critical_section(state);
+		}
+		break;
+
+	case LOCK_THREADS:
+		SPI_LOCK(_dev, true);
+		result = _transferhword(send, recv, len);
+		SPI_LOCK(_dev, false);
+		break;
+
+	case LOCK_NONE:
+		result = _transferhword(send, recv, len);
+		break;
+	}
+
+	return result;
+}
+
+int
+SPI::_transferhword(uint16_t *send, uint16_t *recv, unsigned len)
+{
+	SPI_SETFREQUENCY(_dev, _frequency);
+	SPI_SETMODE(_dev, _mode);
+	SPI_SETBITS(_dev, 16);							/* 16 bit transfer */
+	SPI_SELECT(_dev, _device, true);
+
+	/* do the transfer */
+	SPI_EXCHANGE(_dev, send, recv, len);
+
+	/* and clean up */
+	SPI_SELECT(_dev, _device, false);
+
+	return OK;
+}
+
 } // namespace device

src/drivers/device/nuttx/SPI.hpp

@@ -108,6 +108,27 @@ protected:
 	 */
 	int		transfer(uint8_t *send, uint8_t *recv, unsigned len);
 
+	/**
+	 * Perform a SPI 16 bit transfer.
+	 *
+	 * If called from interrupt context, this interface does not lock
+	 * the bus and may interfere with non-interrupt-context callers.
+	 *
+	 * Clients in a mixed interrupt/non-interrupt configuration must
+	 * ensure appropriate interlocking.
+	 *
+	 * At least one of send or recv must be non-null.
+	 *
+	 * @param send		Words to send to the device, or nullptr if
+	 *			no data is to be sent.
+	 * @param recv		Words for receiving bytes from the device,
+	 *			or nullptr if no bytes are to be received.
+	 * @param len		Number of words to transfer.
+	 * @return		OK if the exchange was successful, -errno
+	 *			otherwise.
+	 */
+	int		transferhword(uint16_t *send, uint16_t *recv, unsigned len);
+
 	/**
 	 * Set the SPI bus frequency
 	 * This is used to change frequency on the fly. Some sensors
@@ -144,6 +165,8 @@ private:
 protected:
 	int	_transfer(uint8_t *send, uint8_t *recv, unsigned len);
 
+	int	_transferhword(uint16_t *send, uint16_t *recv, unsigned len);
+
 	bool	external() { return px4_spi_bus_external(get_device_bus()); }
 
 };