preempt: introduce idle process; timer: use managed irqs for preemption

[bertos.git] / bertos / kern / preempt.c

diff --git a/bertos/kern/preempt.c b/bertos/kern/preempt.c
index f068a8a82c24d314d159e84a045422de18b55475..7ecd481d0cdf57c6d4c3679fc4ccfa43f5cc794e 100644 (file)
--- a/bertos/kern/preempt.c
+++ b/bertos/kern/preempt.c
@@ -26,27 +26,27 @@
  * invalidate any other reasons why the executable file might be covered by
  * the GNU General Public License.
  *
- * Copyright 2001, 2004 Develer S.r.l. (http://www.develer.com/)
- * Copyright 1999, 2000, 2001, 2008 Bernie Innocenti <bernie@codewiz.org>
+ * Copyright 2008 Bernie Innocenti <bernie@codewiz.org>
  * -->
  *
- * \brief Simple realtime multitasking scheduler.
- *        Context switching is only done cooperatively.
+ * \brief Simple preemptive multitasking scheduler.
  *
  * \version $Id: proc.c 1616 2008-08-10 19:41:26Z bernie $
  * \author Bernie Innocenti <bernie@codewiz.org>
- * \author Stefano Fedrigo <aleph@develer.com>
  */
 
 #include "proc_p.h"
 #include "proc.h"
 
+#include <kern/irq.h>
+#include <kern/monitor.h>
+#include <cpu/frame.h> // CPU_IDLE
+#include <drv/timer.h>
+#include <cfg/module.h>
+
 
-/*
- * The time sharing scheduler forces a task switch when the current
- * process has exhausted its quantum.
- */
-uint16_t Quantum;
+
+Timer preempt_timer;
 
 /**
  * Disable preemptive task switching.
@@ -78,3 +78,100 @@ void proc_permit(void)
        /* No need to protect against interrupts here. */
        --CurrentProcess->forbid_cnt;
 }
+
+
+void proc_preempt(void)
+{
+       IRQ_DISABLE;
+
+       LIST_ASSERT_VALID(&ProcReadyList);
+       CurrentProcess = (struct Process *)list_remHead(&ProcReadyList);
+       LIST_ASSERT_VALID(&ProcReadyList);
+       ASSERT2(CurrentProcess, "no idle proc?");
+
+       IRQ_ENABLE;
+
+       TRACEMSG("new proc: %p:%s", CurrentProcess, CurrentProcess ? CurrentProcess->monitor.name : "---");
+       monitor_report();
+}
+
+void proc_preempt_timer(UNUSED_ARG(void *, param))
+{
+       IRQ_DISABLE;
+/*
+       if (!CurrentProcess->forbid_cnt)
+       {
+               TRACEMSG("preempting %p:%s", CurrentProcess, CurrentProcess->monitor.name);
+               LIST_ASSERT_VALID(&ProcReadyList);
+               SCHED_ENQUEUE(CurrentProcess);
+               proc_preempt();
+       }
+*/
+       IRQ_ENABLE;
+
+       timer_setDelay(&preempt_timer, CONFIG_KERN_QUANTUM);
+       timer_add(&preempt_timer);
+}
+
+void proc_schedule(void)
+{
+       TRACE;
+
+       // Will invoke proc_preempt() in interrupt context
+       kill(0, SIGUSR1);
+}
+
+void proc_yield(void)
+{
+       TRACE;
+
+       ASSERT_IRQ_ENABLED();
+       IRQ_DISABLE;
+       SCHED_ENQUEUE(CurrentProcess);
+       LIST_ASSERT_VALID(&ProcReadyList);
+       proc_schedule();
+       IRQ_ENABLE;
+}
+
+void proc_entry(void (*user_entry)(void))
+{
+       user_entry();
+       proc_exit();
+}
+
+
+static cpustack_t idle_stack[CONFIG_PROC_DEFSTACKSIZE / sizeof(cpustack_t)];
+
+/*
+ * The idle process
+ *
+ * This process never dies and never sleeps.  It's also quite apathic
+ * and a bit antisocial.
+ *
+ * Having an idle process costs some stack space, but simplifies the
+ * interrupt-driven preemption logic because there is always a user
+ * context to which we can return.
+ */
+static NORETURN void idle(void)
+{
+       for (;;)
+       {
+               TRACE;
+               monitor_report();
+               proc_yield(); // FIXME: CPU_IDLE
+       }
+}
+
+void preempt_init(void)
+{
+       MOD_CHECK(irq);
+       MOD_CHECK(timer);
+
+       irq_register(SIGUSR1, proc_preempt);
+
+       timer_setSoftint(&preempt_timer, proc_preempt_timer, NULL);
+       timer_setDelay(&preempt_timer, CONFIG_KERN_QUANTUM);
+       timer_add(&preempt_timer);
+
+       proc_new(idle, NULL, sizeof(idle_stack), idle_stack);
+}