EFM32: Add I2C driver. From Pierre-noel Bouteville

arch/arm/src/efm32/Kconfig

@@ -137,6 +137,14 @@ config EFM32_RMU_DEBUG
 	default n
 	depends on EFM32_RMU && DEBUG
 
+config EFM32_I2C0
+	bool "I2C0"
+	default n
+
+config EFM32_I2C1
+	bool "I2C1"
+	default n
+
 config EFM32_USART0
 	bool "USART0"
 	default n

arch/arm/src/efm32/Make.defs

@@ -101,7 +101,7 @@ CHIP_ASRCS += efm32_vectors.S
 endif
 
 CHIP_CSRCS  = efm32_start.c efm32_clockconfig.c efm32_irq.c efm32_timerisr.c
-CHIP_CSRCS += efm32_gpio.c efm32_lowputc.c efm32_timer.c
+CHIP_CSRCS += efm32_gpio.c efm32_lowputc.c efm32_timer.c efm32_i2c.c
 
 ifneq ($(CONFIG_ARCH_IDLE_CUSTOM),y)
 CHIP_CSRCS += efm32_idle.c

arch/arm/src/efm32/efm32_gpio.c

@@ -314,6 +314,22 @@ int efm32_configgpio(gpio_pinset_t cfgset)
   return OK;
 }
 
+/************************************************************************************
+ * Name: efm32_unconfiggpio
+ *
+ * Description:
+ *   unConfigure a PIO pin based on bit-encoded description of the pin.
+ *
+ ************************************************************************************/
+
+int efm32_unconfiggpio(gpio_pinset_t cfgset)
+{
+  cfgset &= GPIO_PIN_MASK | GPIO_PORT_MASK;
+  cfgset |= _GPIO_DISABLE;
+
+  return efm32_configgpio(cfgset);
+}
+
 /************************************************************************************
  * Name: efm32_gpiowrite
  *

arch/arm/src/efm32/efm32_gpio.h

@@ -256,6 +256,16 @@ void efm32_gpioirqinitialize(void);
 
 int efm32_configgpio(gpio_pinset_t cfgset);
 
+/************************************************************************************
+ * Name: efm32_unconfiggpio
+ *
+ * Description:
+ *   UnConfigure a PIO pin based on bit-encoded description of the pin.
+ *
+ ************************************************************************************/
+
+int efm32_unconfiggpio(gpio_pinset_t cfgset);
+
 /************************************************************************************
  * Name: efm32_gpiowrite
  *