sys/bhp_msg: add IPC based Bottom Half Processor

sys/bhp/Kconfig

@@ -22,4 +22,9 @@ config MODULE_BHP_EVENT
     depends on MODULE_EVENT
     depends on MODULE_BHP
 
+config MODULE_BHP_MSG
+    bool "Enable message based Bottom Half Processor implementation"
+    depends on MODULE_CORE_MSG
+    depends on MODULE_BHP
+
 endmenu

sys/bhp/Makefile.dep

@@ -1,3 +1,7 @@
 ifneq (,$(filter bhp_event,$(USEMODULE)))
   USEMODULE += event
 endif
+
+ifneq (,$(filter bhp_msg,$(USEMODULE)))
+  USEMODULE += core_msg
+endif

sys/bhp/Makefile.include

@@ -1 +1,2 @@
 PSEUDOMODULES += bhp_event
+PSEUDOMODULES += bhp_msg

sys/bhp/msg.c

@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2022 HAW Hamburg
+ *
+ * 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
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     sys_bhp
+ * @{
+ *
+ * @file
+ * @brief       Message based Bottom Half Processor implementation
+ *
+ * @author      José I. Alamos <jose.alamos@haw-hamburg.de>
+ *
+ * @}
+ */
+#include <stdio.h>
+#include "bhp/msg.h"
+
+void bhp_msg_init(bhp_msg_t *bhp_msg, bhp_cb_t cb, void *ctx)
+{
+    bhp_set_cb(&bhp_msg->bhp, cb, ctx);
+    bhp_msg->pid = KERNEL_PID_UNDEF;
+    bhp_msg->msg.type = BHP_MSG_BH_REQUEST;
+    bhp_msg->msg.content.ptr = &bhp_msg->bhp;
+}
+
+void bhp_msg_isr_cb(void *bhp_msg_ctx)
+{
+    bhp_msg_t *bhp_msg = bhp_msg_ctx;
+
+    assert(bhp_msg->pid != KERNEL_PID_UNDEF);
+    msg_send(&bhp_msg->msg, bhp_msg->pid);
+}

sys/include/bhp/msg.h

@@ -0,0 +1,106 @@
+/*
+ * Copyright (C) 2022 HAW Hamburg
+ *
+ * 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 directory for more
+ * details.
+ */
+
+/**
+ * @defgroup     sys_bhp_msg Message based implementation of Bottom Half Processor
+ * @ingroup      sys_bhp
+ *
+ * @note         Offloading ISRs with messages is in general a terrible idea,
+ *               because messages can be lost. Use it with care or prefer
+ *               alternatives such as @ref sys_bhp_event.
+ *
+ * @brief        Bottom Half Processor module for generic IRQ offloading using
+ *               messages.
+ * @{
+ *
+ * @author       José I. Alamos <jose.alamos@haw-hamburg.de>
+ */
+
+#ifndef BHP_MSG_H
+#define BHP_MSG_H
+
+#include "msg.h"
+#include "thread.h"
+#include "bhp.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief   The message type to trigger Bottom Half Processing
+ */
+#define BHP_MSG_BH_REQUEST 0x1539
+
+/**
+ * @brief Message based Bottom Half Processor descriptor
+ */
+typedef struct {
+    bhp_t bhp;          /**< Bottom Half Processor descriptor */
+    kernel_pid_t pid;   /**< PID of the thread that process the Bottom Half Processor */
+    msg_t msg;          /**< Message containing the Bottom Half Processing request */
+} bhp_msg_t;
+
+/**
+ * @brief Init a Bottom Half Processor to be used with messages
+ * @post the target PID is set to @ref KERNEL_PID_UNDEF
+ *
+ * @param[in] bhp_msg   The message based Bottom Half Processor descriptor
+ * @param[in] cb        Bottom Half Processor callback
+ * @param[in] ctx       Context of @p cb
+ */
+void bhp_msg_init(bhp_msg_t *bhp_msg, bhp_cb_t cb, void *ctx);
+
+/**
+ * @brief Message based Bottom Half Processor ISR callback
+ *        To be called from ISR in order to trigger the Bottom Half Processor.
+ *        This sends a message with type @ref BHP_MSG_BH_REQUEST to the
+ *        target thread, which should process the event accordingly by calling
+ *        @ref bhp_msg_handler.
+ *
+ * @note This function asserts that the target PID is valid. Therefore, make sure
+ * to call @ref bhp_msg_claim_thread beforehand.
+ *
+ * @param[in] bhp_msg_ctx     Pointer to the message based Bottom Half Processor
+ * (@ref bhp_msg_t)
+ *                            Bottom Half Processor.
+ */
+void bhp_msg_isr_cb(void *bhp_msg_ctx);
+
+/**
+ * @brief Claim a thread with a message queue to be used as Bottom Half Processor.
+ *
+ * @param[in] bhp_msg    The message based Bottom Half Processor descriptor
+ * @param[in] pid        PID of the target thread
+ */
+static inline void bhp_msg_claim_thread(bhp_msg_t *bhp_msg, kernel_pid_t pid)
+{
+    bhp_msg->pid = pid;
+}
+
+/**
+ * @brief   Handle a Bottom Half Processor message with type @ref
+ *          BHP_MSG_BH_REQUEST.
+ *          This function will call @ref bhp_irq_handler internally.
+ *
+ * @note This function asserts that the message type is @ref BHP_MSG_BH_REQUEST.
+ *
+ * @param[in] msg   Pointer to the Bottom Half Processor message.
+ */
+static inline void bhp_msg_handler(msg_t *msg)
+{
+    assert(msg->type == BHP_MSG_BH_REQUEST);
+    bhp_irq_handler(msg->content.ptr);
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* BHP_MSG_H */
+/** @} */