sched: major refactor

arch/at91sam3x8e/sched.c

@@ -3,16 +3,14 @@
 
 #include <arch/sched.h>
 #include <arch/at91sam3x8e/hardware.h>
+#include <arch/at91sam3x8e/interrupt.h>
+
 #include <ardix/string.h>
 #include <ardix/sched.h>
+
 #include <stdbool.h>
 #include <toolchain.h>
 
-#ifdef __cplusplus
-extern "C"
-{
-#endif /* __cplusplus */
-
 /**
  * Set the PENDSV bit in the system control block.
  */
@@ -30,7 +28,7 @@ void irq_sys_tick(void)
 	sched_pendsv_req();
 }
 
-void sched_init_process_regs(struct reg_snapshot *reg_snap, void (*entry)(void))
+void sched_init_process_regs(struct reg_snapshot *reg_snap, int (*entry)(void))
 {
 	memset(reg_snap, 0, sizeof(*reg_snap));
 
@@ -57,7 +55,7 @@ static inline void sched_nvic_set_prio_group(uint32_t prio_group)
 	REG_SCB_AIRCR = reg_val;
 }
 
-int sched_hwtimer_init(unsigned int freq)
+int arch_sched_hwtimer_init(unsigned int freq)
 {
 	uint32_t ticks = sys_core_clock / freq;
 	if (ticks > REG_SYSTICK_LOAD_RELOAD_MASK)
@@ -75,14 +73,13 @@ int sched_hwtimer_init(unsigned int freq)
 	return 0;
 }
 
-inline void sched_atomic_enter(void)
+void arch_sched_process_init(struct process *process, void (*entry)(void))
 {
-	REG_SYSTICK_CTRL &= ~REG_SYSTICK_CTRL_ENABLE_BIT;
-}
+	struct reg_snapshot *regs = process->stack_bottom - sizeof(*regs);
+	process->sp = regs;
 
-inline void sched_atomic_leave(bool resched)
-{
-	REG_SYSTICK_CTRL |= REG_SYSTICK_CTRL_ENABLE_BIT;
+	memset(regs, 0, sizeof(*regs));
+	regs->hw.pc = (void *)((uint32_t)entry | 1U); /* thumb instruction set flag */
 }
 
 void sched_exec_early(void)
@@ -91,10 +88,6 @@ void sched_exec_early(void)
 	sched_pendsv_req();
 }
 
-#ifdef __cplusplus
-} /* extern "C" */
-#endif /* __cplusplus */
-
 /*
  * Copyright (c) 2020 Felix Kopp <sandtler@sandtler.club>
  *

include/arch/at91sam3x8e/interrupt.h

@@ -20,7 +20,7 @@ void irq_svc(void);
 /** Debug handler (reserved) */
 void irq_debug_mon(void);
 /** Pending SV interrupt handler */
-extern void irq_pend_sv(void);
+void irq_pend_sv(void);
 /** SysTick interrupt handler */
 void irq_sys_tick(void);
 

include/arch/at91sam3x8e/sched.h

@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+/* See the end of this file for copyright, licensing, and warranty information. */
+
+#pragma once
+
+#include <arch/at91sam3x8e/interrupt.h>
+#include <ardix/sched.h>
+#include <toolchain.h>
+
+/** Enter atomic context, i.e. disable preemption */
+__always_inline void sched_atomic_enter(void)
+{
+	arch_irq_disable(IRQNO_PEND_SV);
+}
+
+/** Leave atomic context, i.e. re-enable preemption */
+__always_inline void sched_atomic_leave(void)
+{
+	arch_irq_enable(IRQNO_PEND_SV);
+}
+
+/*
+ * Copyright (c) 2020 Felix Kopp <sandtler@sandtler.club>
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are permitted
+ * provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this list of
+ *    conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
+ *    conditions and the following disclaimer in the documentation and/or other materials
+ *    provided with the distribution.
+ * 3. Neither the name of the copyright holder nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software without specific prior
+ *    written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
+ * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */

include/arch/sched.h

@@ -4,43 +4,34 @@
 #pragma once
 
 #include <arch/hardware.h>
+
 #include <stdbool.h>
+#include <toolchain.h>
+
+struct process; /* see include/ardix/sched.h */
 
 /**
  * Initialize a hardware timer for schduling.
  *
  * @param freq: The timer frequency in Hertz.
  */
-int sched_hwtimer_init(unsigned int freq);
+int arch_sched_hwtimer_init(unsigned int freq);
 
 /**
- * Disable all scheduling interrupts in order to enter atomic context.
- */
-void sched_atomic_enter(void);
-
-/**
- * Re-enable scheduling interrupts, i.e. leave atomic context.
+ * Initialize a new process.
+ * This requires the process' `stack_base` field to be initialized as the
+ * initial register values are written to the stack.
  *
- * @param resched: If `true`, request the scheduler to proceed to the next
- *	process ASAP.  Until then, put the CPU to sleep if required.
- */
-void sched_atomic_leave(bool resched);
-
-/**
- * Infinite loop of sleep instructions.
- */
-void sched_idle_process_loop(void);
-
-/**
- * Initialize the register values of a newly allocated process image.
- * Called by the scheduling subsystem when a process is being created.
- *
- * @param reg_snap: The stack memory location where the initial register values
- *	are to be loaded from.
+ * @param process: The process.
  * @param entry: The process entry point.
  */
-void sched_init_process_regs(struct reg_snapshot *reg_snap,
-			     void (*entry)(void));
+void arch_sched_process_init(struct process *process, void (*entry)(void));
+
+#ifdef ARCH_AT91SAM3X8E
+#include <arch/at91sam3x8e/sched.h>
+#else
+#error "Unsupported architecture"
+#endif
 
 /*
  * Copyright (c) 2020 Felix Kopp <sandtler@sandtler.club>