cpu/efm32: move LOW_POWER_ENABLED to efm32-features.mk

boards/slstk3401a/doc.txt

@@ -151,8 +151,6 @@ You can override the branch's clock source by adding `CLOCK_LFA=source` to your
 ### Low-power peripherals
 The low-power UART is capable of providing an UART peripheral using a low-speed clock. When the LFB clock source is the LFRCO or LFXO, it can still be used in EM2. However, this limits the baud rate to 9600 baud. If a higher baud rate is desired, set the clock source to CORELEDIV2.
 
-If you don't need low-power peripheral support, passing `LOW_POWER_ENABLED=0` to the compiler will disable support in the drivers (currently LEUART). This feature costs approximately 600 bytes (default compilation settings, LEUART only).
-
 **Note:** peripheral mappings in your board definitions will not be affected by this setting. Ensure you do not refer to any low-power peripherals.
 
 ### RTC or RTT

boards/slstk3402a/doc.txt

@@ -153,8 +153,6 @@ You can override the branch's clock source by adding `CLOCK_LFA=source` to your
 ### Low-power peripherals
 The low-power UART is capable of providing an UART peripheral using a low-speed clock. When the LFB clock source is the LFRCO or LFXO, it can still be used in EM2. However, this limits the baud rate to 9600 baud. If a higher baud rate is desired, set the clock source to CORELEDIV2.
 
-If you don't need low-power peripheral support, passing `LOW_POWER_ENABLED=0` to the compiler will disable support in the drivers (currently LEUART). This feature costs approximately 600 bytes (default compilation settings, LEUART only).
-
 **Note:** peripheral mappings in your board definitions will not be affected by this setting. Ensure you do not refer to any low-power peripherals.
 
 ### RTC or RTT

boards/sltb001a/doc.txt

@@ -139,8 +139,6 @@ You can override the branch's clock source by adding `CLOCK_LFA=source` to your
 ### Low-power peripherals
 The low-power UART is capable of providing an UART peripheral using a low-speed clock. When the LFB clock source is the LFRCO or LFXO, it can still be used in EM2. However, this limits the baud rate to 9600 baud. If a higher baud rate is desired, set the clock source to CORELEDIV2.
 
-If you don't need low-power peripheral support, passing `LOW_POWER_ENABLED=0` to the compiler will disable support in the drivers (currently LEUART). This feature costs approximately 600 bytes (default compilation settings, LEUART only).
-
 **Note:** peripheral mappings in your board definitions will not be affected by this setting. Ensure you do not refer to any low-power peripherals.
 
 ### RTC or RTT

cpu/efm32/Makefile.features

@@ -15,4 +15,8 @@ ifeq (1,$(EFM32_UART_MODES))
   CFLAGS += -DEFM32_UART_MODES=1
 endif
 
+ifeq (1,$(EFM32_LEUART_ENABLED))
+  CFLAGS += -DEFM32_LEUART_ENABLED=1
+endif
+
 include $(RIOTCPU)/cortexm_common/Makefile.features

cpu/efm32/doc.txt

@@ -62,7 +62,12 @@
  * =======================
  *
  * The EFM32/EFR32/EZR32 MCUs have support for low-power peripherals. Support
- * is enabled by default, but can be disabled by setting LOW_POWER_ENABLED=0.
+ * is enabled by default, but can be disabled if not used.
+ *
+ * - Setting `EFM32_LEUART_ENABLED=0` will disable support for the LEUART
+ *   in the UART driver peripheral and save approximately 400 bytes.
+ *
+ * Refer to `cpu/efm32/efm32-features.mk` for more options.
  */
 
 /**

cpu/efm32/efm32-features.mk

@@ -2,3 +2,4 @@
 # should override them from the command line, or in your Makefile. Note that
 # some features may not be applicable to all EFM32 boards or CPUs.
 export EFM32_UART_MODES ?= 0
+export EFM32_LEUART_ENABLED ?= 1

cpu/efm32/include/periph_cpu.h

@@ -38,15 +38,6 @@
 extern "C" {
 #endif
 
-/**
- * @brief   Enable support for Low-power peripherals (if supported by CPU).
- * @{
- */
-#ifndef LOW_POWER_ENABLED
-#define LOW_POWER_ENABLED   (1)
-#endif
-/** @} */
-
 /**
  * @brief   Internal macro for combining ADC resolution (x) with number of
  *          shifts (y).

cpu/efm32/periph/uart.c

@@ -27,7 +27,15 @@
 
 #include "em_usart.h"
 #include "em_usart_utils.h"
-#if LOW_POWER_ENABLED && defined(LEUART_COUNT) && LEUART_COUNT > 0
+
+/**
+ * @brief   Defines whether LEUART is enabled and supported
+ */
+#if EFM32_LEUART_ENABLED && defined(LEUART_COUNT) && LEUART_COUNT > 0
+#define USE_LEUART
+#endif
+
+#ifdef USE_LEUART
 #include "em_leuart.h"
 #include "em_leuart_utils.h"
 #endif
@@ -37,13 +45,15 @@
  */
 static uart_isr_ctx_t isr_ctx[UART_NUMOF];
 
+#ifdef USE_LEUART
 /**
  * @brief   Check if device is a U(S)ART device.
  */
 static inline bool _is_usart(uart_t dev)
 {
     return ((uint32_t) uart_config[dev].dev) < LEUART0_BASE;
 }
+#endif
 
 int uart_init(uart_t dev, uint32_t baudrate, uart_rx_cb_t rx_cb, void *arg)
 {
@@ -61,7 +71,7 @@ int uart_init(uart_t dev, uint32_t baudrate, uart_rx_cb_t rx_cb, void *arg)
     gpio_init(uart_config[dev].tx_pin, GPIO_OUT);
 
     /* initialize the UART/USART/LEUART device */
-#if LOW_POWER_ENABLED && defined(LEUART_COUNT) && LEUART_COUNT > 0
+#ifdef USE_LEUART
     if (_is_usart(dev)) {
 #endif
         USART_TypeDef *uart = (USART_TypeDef *) uart_config[dev].dev;
@@ -98,7 +108,7 @@ int uart_init(uart_t dev, uint32_t baudrate, uart_rx_cb_t rx_cb, void *arg)
 
         /* enable peripheral */
         USART_Enable(uart, usartEnable);
-#if LOW_POWER_ENABLED && defined(LEUART_COUNT) && LEUART_COUNT > 0
+#ifdef USE_LEUART
     } else {
         LEUART_TypeDef *leuart = (LEUART_TypeDef *) uart_config[dev].dev;
 
@@ -146,13 +156,13 @@ int uart_init(uart_t dev, uint32_t baudrate, uart_rx_cb_t rx_cb, void *arg)
 
 void uart_write(uart_t dev, const uint8_t *data, size_t len)
 {
-#if LOW_POWER_ENABLED && defined(LEUART_COUNT) && LEUART_COUNT > 0
+#ifdef USE_LEUART
     if (_is_usart(dev)) {
 #endif
         while (len--) {
             USART_Tx(uart_config[dev].dev, *(data++));
         }
-#if LOW_POWER_ENABLED && defined(LEUART_COUNT) && LEUART_COUNT > 0
+#ifdef USE_LEUART
     } else {
         while (len--) {
             LEUART_Tx(uart_config[dev].dev, *(data++));
@@ -173,13 +183,13 @@ void uart_poweroff(uart_t dev)
 
 static void rx_irq(uart_t dev)
 {
-#if LOW_POWER_ENABLED && defined(LEUART_COUNT) && LEUART_COUNT > 0
+#ifdef USE_LEUART
     if (_is_usart(dev)) {
 #endif
         if (USART_IntGet(uart_config[dev].dev) & USART_IF_RXDATAV) {
             isr_ctx[dev].rx_cb(isr_ctx[dev].arg, USART_RxDataGet(uart_config[dev].dev));
         }
-#if LOW_POWER_ENABLED && defined(LEUART_COUNT) && LEUART_COUNT > 0
+#ifdef USE_LEUART
     } else {
         if (LEUART_IntGet(uart_config[dev].dev) & LEUART_IF_RXDATAV) {
             isr_ctx[dev].rx_cb(isr_ctx[dev].arg, LEUART_RxDataGet(uart_config[dev].dev));

tests/cpu_efm32_features/Makefile

@@ -11,5 +11,6 @@ BOARD_WHITELIST := ikea-tradfri \
 
 # see cpu/efm32/efm32-features.mk for the supported flags
 EFM32_UART_MODES = 1
+EFM32_LEUART_ENABLED = 0
 
 include $(RIOTBASE)/Makefile.include

tests/cpu_efm32_features/README.md

@@ -3,7 +3,8 @@
 ## Introduction
 The EFM32 support several features that can be toggled compile-time.
 
-This test will ensure that RIOT-OS will compile whenever these features are toggled.
+This test will ensure that RIOT-OS will compile whenever these features are
+toggled.
 
 ## Expected result
 The test application compiles for EFM32-based boards.

tests/cpu_efm32_features/main.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2018 Bas Stottelaar <basstottelaar@gmail.com>
+ * Copyright (C) 2018-2019 Bas Stottelaar <basstottelaar@gmail.com>
  *
  * This file is subject to the terms and conditions of the GNU Lesser
  * General Public License v2.1. See the file LICENSE in the top level
@@ -20,6 +20,10 @@
 
 #include "periph/uart.h"
 
+#if EFM32_LEUART_ENABLED
+#error "Expected EFM32_LEUART_ENABLED feature to be disabled."
+#endif
+
 int main(void)
 {
     /* test if uart_config[i].mode is set to a know value */