kernel: DPC support

kernel-src/sys/dpc.c

@@ -0,0 +1,74 @@
+#include <kernel/dpc.h>
+#include <arch/cpu.h>
+#include <kernel/interrupt.h>
+#include <logging.h>
+
+static isr_t *dpcisr;
+
+static void remove(dpc_t *dpc) {
+	if (dpc->prev)
+		dpc->prev->next = dpc->next;
+	else 
+		_cpu()->dpcqueue = dpc->next;
+
+	if (dpc->next)
+		dpc->next->prev = dpc->prev;
+}
+
+static void insert(dpc_t *dpc) {
+	dpc->prev = NULL;
+	dpc->next = _cpu()->dpcqueue;
+
+	if (dpc->next)
+		dpc->next->prev = dpc;
+
+	_cpu()->dpcqueue = dpc;
+}
+
+static void isrfn(isr_t *self, context_t *context) {
+	while (_cpu()->dpcqueue) {
+		dpc_t *dpc = _cpu()->dpcqueue;
+		remove(dpc);
+
+		__assert(dpc->enqueued);
+		dpc->enqueued = false;
+
+		interrupt_set(true);
+		dpc->fn(context, dpc->arg);
+		interrupt_set(false);
+	}
+}
+
+void dpc_enqueue(dpc_t *dpc, dpcfn_t fn, dpcarg_t arg) {
+	bool entrystate = interrupt_set(false);
+
+	if (dpc->enqueued)
+		goto cleanup;
+
+	dpc->fn = fn;
+	dpc->arg = arg;
+	dpc->enqueued = true;
+	insert(dpc);
+	interrupt_raise(dpcisr);
+
+	cleanup:
+	interrupt_set(entrystate);
+}
+
+void dpc_dequeue(dpc_t *dpc) {
+	bool entrystate = interrupt_set(false);
+
+	if (dpc->enqueued == false)
+		goto cleanup;
+
+	dpc->enqueued = false;
+	remove(dpc);
+
+	cleanup:
+	interrupt_set(entrystate);
+}
+
+void dpc_init() {
+	dpcisr = interrupt_allocate(isrfn, NULL, IPL_DPC);
+	__assert(dpcisr);
+}