Use the generic device::SPI locking strategy.

src/drivers/device/spi.cpp

@@ -67,6 +67,7 @@ SPI::SPI(const char *name,
 	CDev(name, devname, irq),
 	// public
 	// protected
+	locking_mode(LOCK_PREEMPTION),
 	// private
 	_bus(bus),
 	_device(device),
@@ -132,13 +133,25 @@ SPI::probe()
 int
 SPI::transfer(uint8_t *send, uint8_t *recv, unsigned len)
 {
+	irqstate_t	state;
 
 	if ((send == nullptr) && (recv == nullptr))
 		return -EINVAL;
 
-	/* do common setup */
+	/* lock the bus as required */
-	if (!up_interrupt_context())
+	if (!up_interrupt_context()) {
+		switch (locking_mode) {
+		default:
+		case LOCK_PREEMPTION:
+			state = irqsave();
+			break;
+		case LOCK_THREADS:
 			SPI_LOCK(_dev, true);
+			break;
+		case LOCK_NONE:
+			break;
+		}
+	}
 
 	SPI_SETFREQUENCY(_dev, _frequency);
 	SPI_SETMODE(_dev, _mode);
@@ -151,8 +164,19 @@ SPI::transfer(uint8_t *send, uint8_t *recv, unsigned len)
 	/* and clean up */
 	SPI_SELECT(_dev, _device, false);
 
-	if (!up_interrupt_context())
+	if (!up_interrupt_context()) {
+		switch (locking_mode) {
+		default:
+		case LOCK_PREEMPTION:
+			irqrestore(state);
+			break;
+		case LOCK_THREADS:
 			SPI_LOCK(_dev, false);
+			break;
+		case LOCK_NONE:
+			break;
+		}
+	}
 
 	return OK;
 }

src/drivers/device/spi.h

@@ -101,6 +101,17 @@ protected:
 	 */
 	int		transfer(uint8_t *send, uint8_t *recv, unsigned len);
 
+	/**
+	 * Locking modes supported by the driver.
+	 */
+	enum LockMode {
+		LOCK_PREEMPTION,	/**< the default; lock against all forms of preemption. */
+		LOCK_THREADS,		/**< lock only against other threads, using SPI_LOCK */
+		LOCK_NONE		/**< perform no locking, only safe if the bus is entirely private */
+	};
+
+	LockMode	locking_mode;	/**< selected locking mode */
+
 private:
 	int			_bus;
 	enum spi_dev_e		_device;

src/drivers/l3gd20/l3gd20.cpp

@@ -367,7 +367,6 @@ out:
 int
 L3GD20::probe()
 {
-	irqstate_t flags = irqsave();
 	/* read dummy value to void to clear SPI statemachine on sensor */
 	(void)read_reg(ADDR_WHO_AM_I);
 
@@ -393,8 +392,6 @@ L3GD20::probe()
 		success = true;
 	}
 
-	irqrestore(flags);
-
 	if (success)
 		return OK;
 

src/drivers/lsm303d/lsm303d.cpp

@@ -525,7 +525,6 @@ out:
 void
 LSM303D::reset()
 {
-	irqstate_t flags = irqsave();
 	/* enable accel*/
 	write_reg(ADDR_CTRL_REG1, REG1_X_ENABLE_A | REG1_Y_ENABLE_A | REG1_Z_ENABLE_A | REG1_BDU_UPDATE);
 
@@ -540,7 +539,6 @@ LSM303D::reset()
 
 	mag_set_range(LSM303D_MAG_DEFAULT_RANGE_GA);
 	mag_set_samplerate(LSM303D_MAG_DEFAULT_RATE);
-	irqrestore(flags);
 
 	_accel_read = 0;
 	_mag_read = 0;
@@ -549,15 +547,12 @@ LSM303D::reset()
 int
 LSM303D::probe()
 {
-	irqstate_t flags = irqsave();
 	/* read dummy value to void to clear SPI statemachine on sensor */
 	(void)read_reg(ADDR_WHO_AM_I);
 
 	/* verify that the device is attached and functioning */
 	bool success = (read_reg(ADDR_WHO_AM_I) == WHO_I_AM);
 	
-	irqrestore(flags);
-
 	if (success)
 		return OK;
 

src/drivers/ms5611/ms5611_spi.cpp

@@ -142,23 +142,15 @@ MS5611_SPI::init()
 		goto out;
 	}
 
-	/* disable interrupts, make this section atomic */
-	flags = irqsave();
 	/* send reset command */
 	ret = _reset();
-	/* re-enable interrupts */
-	irqrestore(flags);
 	if (ret != OK) {
 		debug("reset failed");
 		goto out;
 	}
 
-	/* disable interrupts, make this section atomic */
-	flags = irqsave();
 	/* read PROM */
 	ret = _read_prom();
-	/* re-enable interrupts */
-	irqrestore(flags);
 	if (ret != OK) {
 		debug("prom readout failed");
 		goto out;
@@ -270,13 +262,7 @@ MS5611_SPI::_reg16(unsigned reg)
 int
 MS5611_SPI::_transfer(uint8_t *send, uint8_t *recv, unsigned len)
 {
-	irqstate_t flags = irqsave();
+	return transfer(send, recv, len);
-
-	int ret = transfer(send, recv, len);
-
-	irqrestore(flags);
-
-	return ret;
 }
 
 #endif /* PX4_SPIDEV_BARO */