From 7fcb2b718ec7149976b79333ded54d28a6594630 Mon Sep 17 00:00:00 2001
From: Kaspar Schleiser <kaspar@schleiser.de>
Date: Mon, 14 Sep 2015 00:27:27 +0200
Subject: [PATCH] cpu: atmega: implement irq_arch_in

---
 cpu/atmega2560/periph/gpio.c    |  2 ++
 cpu/atmega2560/periph/uart.c    |  8 ++++++++
 cpu/atmega_common/include/cpu.h | 28 ++++++++++++++++++++++++++--
 cpu/atmega_common/irq_arch.c    |  9 ++++-----
 4 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/cpu/atmega2560/periph/gpio.c b/cpu/atmega2560/periph/gpio.c
index 275e1dc7eb..610fa9936e 100644
--- a/cpu/atmega2560/periph/gpio.c
+++ b/cpu/atmega2560/periph/gpio.c
@@ -215,7 +215,9 @@ void gpio_write(gpio_t pin, int value)
 
 static inline void irq_handler(uint8_t pin_num)
 {
+    __enter_isr();
     config[pin_num].cb(config[pin_num].arg);
+    __exit_isr();
 }
 
 ISR(INT0_vect, ISR_BLOCK)
diff --git a/cpu/atmega2560/periph/uart.c b/cpu/atmega2560/periph/uart.c
index b68aeb1194..e2a1643e5c 100644
--- a/cpu/atmega2560/periph/uart.c
+++ b/cpu/atmega2560/periph/uart.c
@@ -276,44 +276,52 @@ int uart_write_blocking(uart_t uart, char data)
 #if UART_0_EN
 ISR(USART0_RX_vect, ISR_BLOCK)
 {
+    __enter_isr();
     config[UART_0].rx_cb(config[UART_0].arg, UART0_DATA_REGISTER);
 
     if (sched_context_switch_request) {
         thread_yield();
     }
+    __exit_isr();
 }
 #endif /* UART_0_EN */
 
 #if UART_1_EN
 ISR(USART1_RX_vect, ISR_BLOCK)
 {
+    __enter_isr();
     config[UART_1].rx_cb(config[UART_1].arg, UART0_DATA_REGISTER);
 
     if (sched_context_switch_request) {
         thread_yield();
     }
+    __exit_isr();
 }
 #endif /* UART_1_EN */
 
 #if UART_1_EN
 ISR(USART2_RX_vect, ISR_BLOCK)
 {
+    __enter_isr();
     config[UART_2].rx_cb(config[UART_2].arg, UART0_DATA_REGISTER);
 
     if (sched_context_switch_request) {
         thread_yield();
     }
+    __exit_isr();
 }
 #endif /* UART_2_EN */
 
 #if UART_2_EN
 ISR(USART2_RX_vect, ISR_BLOCK)
 {
+    __enter_isr();
     config[UART_3].rx_cb(config[UART_3].arg, UART0_DATA_REGISTER);
 
     if (sched_context_switch_request) {
         thread_yield();
     }
+    __exit_isr();
 }
 #endif /* UART_3_EN */
 #endif /* UART_0_EN || UART_1_EN |UART_2_EN| UART3 */
diff --git a/cpu/atmega_common/include/cpu.h b/cpu/atmega_common/include/cpu.h
index 5af3727a4c..b7a83a9557 100644
--- a/cpu/atmega_common/include/cpu.h
+++ b/cpu/atmega_common/include/cpu.h
@@ -1,5 +1,6 @@
 /*
- * Copyright (C) 2014 Freie Universität Berlin, Hinnerk van Bruinehsen
+ * Copyright (C) 2015 Kaspar Schleiser <kaspar@schleiser.de>
+ *               2014 Freie Universität Berlin, Hinnerk van Bruinehsen
  *
  * 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
@@ -20,14 +21,16 @@
  * @author      Stefan Pfeiffer <stefan.pfeiffer@fu-berlin.de>
  * @author      Hauke Petersen <hauke.petersen@fu-berlin.de>
  * @author      Hinnerk van Bruinehsen <h.v.bruinehsen@fu-berlin.de>
+ * @author      Kaspar Schleiser <kaspar@schleiser.de>
  */
 
 #ifndef __ATMEGA_COMMON_H
 #define __ATMEGA_COMMON_H
 
 #include <stdio.h>
-#include <avr/interrupt.h>
+#include <stdint.h>
 
+#include <avr/interrupt.h>
 #include "cpu_conf.h"
 
 /**
@@ -43,6 +46,27 @@ extern "C" {
 #define eINT            enableIRQ
 #define dINT            disableIRQ
 
+/**
+ * @brief global in-ISR state variable
+ */
+extern volatile uint8_t __in_isr;
+
+/**
+ * @brief Flag entering of an ISR
+ */
+static inline void __enter_isr(void)
+{
+    __in_isr = 1;
+}
+
+/**
+ * @brief Flag exiting of an ISR
+ */
+static inline void __exit_isr(void)
+{
+    __in_isr = 0;
+}
+
 /**
  * @brief Initialization of the CPU
  */
diff --git a/cpu/atmega_common/irq_arch.c b/cpu/atmega_common/irq_arch.c
index f494aff41f..61747c4b1d 100644
--- a/cpu/atmega_common/irq_arch.c
+++ b/cpu/atmega_common/irq_arch.c
@@ -20,6 +20,7 @@
  */
 
 #include <stdint.h>
+#include <stdio.h>
 #include "arch/irq_arch.h"
 #include "cpu.h"
 
@@ -29,6 +30,8 @@
 static uint8_t __get_interrupt_state(void);
 static void __set_interrupt_state(uint8_t state);
 
+volatile uint8_t __in_isr = 0;
+
 __attribute__((always_inline)) static inline uint8_t  __get_interrupt_state(void)
 {
     uint8_t sreg;
@@ -84,9 +87,5 @@ void irq_arch_restore(unsigned int state)
  */
 int irq_arch_in(void)
 {
-    /*
-     * TODO: find a way to implement this function (e.g. a static variable dis- or
-     * set and unset in each ISR)
-     */
-    return 0;
+    return __in_isr;
 }