HAL_Linux: added bus scanning test

libraries/AP_HAL_Linux/examples/BusTest/BusTest.pde

@@ -0,0 +1,59 @@
+// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
+
+//
+// scan I2C and SPI buses for expected devices
+//
+
+#include <AP_Common.h>
+#include <AP_Progmem.h>
+#include <AP_HAL.h>
+#include <AP_HAL_Linux.h>
+#include <AP_HAL_Empty.h>
+
+const AP_HAL::HAL& hal = AP_HAL_BOARD_DRIVER;
+
+void setup(void)
+{
+    hal.console->println("BusTest startup...");
+}
+
+static struct {
+    const char *name;
+    enum AP_HAL::SPIDevice dev;
+    uint8_t whoami_reg;
+} whoami_list[] = {
+    { "MPU9250", AP_HAL::SPIDevice_MPU9250, 0x75 | 0x80 },
+    { "LSM9DSO", AP_HAL::SPIDevice_LSM9DS0, 0x0f | 0x80 },
+    { "MPU6000", AP_HAL::SPIDevice_MPU6000, 0x75 | 0x80 },
+};
+
+void loop(void)
+{
+    AP_HAL::SPIDeviceDriver *spi;
+    AP_HAL::Semaphore *spi_sem;
+
+    hal.console->printf("Scanning SPI bus devices\n");
+
+    for (uint8_t i=0; i<sizeof(whoami_list)/sizeof(whoami_list[0]); i++) {
+        spi = hal.spi->device(whoami_list[i].dev);
+        if (spi == NULL) {
+            hal.console->printf("Failed to get SPI device for %s\n", whoami_list[i].name);
+            continue;
+        }
+        spi_sem = spi->get_semaphore();
+        if (!spi_sem->take(1000)) {
+            hal.console->printf("Failed to get SPI semaphore for %s\n", whoami_list[i].name);
+            continue;
+        }
+        uint8_t tx[2] = { whoami_list[i].whoami_reg, 0 };
+        uint8_t rx[2];
+        
+        spi->transaction(tx, rx, 2);
+
+        hal.console->printf("WHO_AM_I for %s: 0x%02x\n", whoami_list[i].name, (unsigned)rx[1]);
+        spi_sem->give();
+    }        
+    hal.scheduler->delay(2000);
+}
+
+AP_HAL_MAIN();

libraries/AP_HAL_Linux/examples/BusTest/Makefile

@@ -0,0 +1 @@
+include ../../../../mk/apm.mk