From ddd0dd14c84ba0bb0c2cfdcfb17dff79a4dea41b Mon Sep 17 00:00:00 2001
From: jflyper <shinoda@jaist.ac.jp>
Date: Fri, 27 Apr 2018 09:46:36 +0900
Subject: [PATCH] Check if a CS pin is already owned by somebody else

---
 src/main/drivers/flash.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/main/drivers/flash.c b/src/main/drivers/flash.c
index 27170c282d..ee9705e6e7 100644
--- a/src/main/drivers/flash.c
+++ b/src/main/drivers/flash.c
@@ -46,14 +46,20 @@ static flashDevice_t flashDevice;
 bool flashInit(const flashConfig_t *flashConfig)
 {
     busdev = &busInstance;
-    busdev->bustype = BUSTYPE_SPI;
-    spiBusSetInstance(busdev, spiInstanceByDevice(SPI_CFG_TO_DEV(flashConfig->spiDevice)));
+
     if (flashConfig->csTag) {
         busdev->busdev_u.spi.csnPin = IOGetByTag(flashConfig->csTag);
     } else {
         return false;
     }
 
+    if (IOGetOwner(busdev->busdev_u.spi.csnPin) != OWNER_SPI_PREINIT) {
+        return false;
+    }
+
+    busdev->bustype = BUSTYPE_SPI;
+    spiBusSetInstance(busdev, spiInstanceByDevice(SPI_CFG_TO_DEV(flashConfig->spiDevice)));
+
     IOInit(busdev->busdev_u.spi.csnPin, OWNER_FLASH_CS, 0);
     IOConfigGPIO(busdev->busdev_u.spi.csnPin, SPI_IO_CS_CFG);
     IOHi(busdev->busdev_u.spi.csnPin);