From b393cdad8de5e17d2422f7bd18206a72f0936384 Mon Sep 17 00:00:00 2001
From: Silvano Seva <silseva@fastwebnet.it>
Date: Mon, 28 Dec 2020 18:06:44 +0100
Subject: [PATCH] Added locking mechanism to MK22FN512xx I2C0 driver to allow
 for multithread use

---
 platform/mcu/MK22FN512xxx12/drivers/I2C0.c | 30 ++++++++++++++++++++++
 platform/mcu/MK22FN512xxx12/drivers/I2C0.h | 20 +++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/platform/mcu/MK22FN512xxx12/drivers/I2C0.c b/platform/mcu/MK22FN512xxx12/drivers/I2C0.c
index 214eb867..181cbe50 100644
--- a/platform/mcu/MK22FN512xxx12/drivers/I2C0.c
+++ b/platform/mcu/MK22FN512xxx12/drivers/I2C0.c
@@ -19,8 +19,12 @@
  ***************************************************************************/
 
 #include "I2C0.h"
+#include <os.h>
 #include <MK22F51212.h>
 
+OS_MUTEX i2c_mutex;
+OS_ERR err;
+
 void i2c0_init()
 {
     SIM->SCGC4 |= SIM_SCGC4_I2C0(1);
@@ -28,6 +32,8 @@ void i2c0_init()
     I2C0->A1   = 0;                 /* Module address when in slave mode */
     I2C0->F    = 0x2C;              /* Divide bus clock by 576           */
     I2C0->C1  |= I2C_C1_IICEN(1);   /* Enable I2C module                 */
+
+    OSMutexCreate(&i2c_mutex, "", &err);
 }
 
 void i2c0_terminate()
@@ -36,6 +42,8 @@ void i2c0_terminate()
 
     I2C0->C1   &= ~I2C_C1_IICEN(1);
     SIM->SCGC4 &= ~SIM_SCGC4_I2C0(1);
+
+    OSMutexDel(&i2c_mutex, OS_OPT_DEL_NO_PEND, &err);
 }
 
 void i2c0_write(uint8_t addr, void* buf, size_t len, bool sendStop)
@@ -110,3 +118,25 @@ bool i2c0_busy()
 {
     return (I2C0->S & I2C_S_BUSY_MASK);
 }
+
+bool i2c0_lockDevice()
+{
+    OSMutexPend(&i2c_mutex, 0, OS_OPT_PEND_NON_BLOCKING, NULL, &err);
+
+    if(err == OS_ERR_NONE)
+    {
+        return true;
+    }
+
+    return false;
+}
+
+void i2c0_lockDeviceBlocking()
+{
+    OSMutexPend(&i2c_mutex, 0, OS_OPT_PEND_BLOCKING, NULL, &err);
+}
+
+void i2c0_releaseDevice()
+{
+    OSMutexPost(&i2c_mutex, OS_OPT_POST_NONE, &err);
+}
diff --git a/platform/mcu/MK22FN512xxx12/drivers/I2C0.h b/platform/mcu/MK22FN512xxx12/drivers/I2C0.h
index 48ef5db6..9ba4947f 100644
--- a/platform/mcu/MK22FN512xxx12/drivers/I2C0.h
+++ b/platform/mcu/MK22FN512xxx12/drivers/I2C0.h
@@ -62,4 +62,24 @@ void i2c0_read(uint8_t addr, void *buf, size_t len);
  */
 bool i2c0_busy();
 
+/**
+ * Acquire exclusive ownership on the I2C peripheral by locking an internal
+ * mutex. This function is nonblocking and returs true if mutex has been
+ * successfully locked by the caller.
+ * @return true if device has been locked.
+ */
+bool i2c0_lockDevice();
+
+/**
+ * Acquire exclusive ownership on the I2C peripheral by locking an internal
+ * mutex. In case mutex is already locked, this function blocks the execution
+ * flow until it becomes free again.
+ */
+void i2c0_lockDeviceBlocking();
+
+/**
+ * Release exclusive ownership on the I2C peripheral.
+ */
+void i2c0_releaseDevice();
+
 #endif /* I2C0_H */