Implement RP2040 hw alarms

1 files changed, 55 insertions, 0 deletions

diff --git a/libhw/rp2040_include/libhw/rp2040_hwalarm.h b/libhw/rp2040_include/libhw/rp2040_hwalarm.h
new file mode 100644
index 0000000..3a7ae10
--- /dev/null
+++ b/libhw/rp2040_include/libhw/rp2040_hwalarm.h
@@ -0,0 +1,55 @@
+/* libhw/rp2040_hwalarm.h - Alarms for the RP2040
+ *
+ * Copyright (C) 2024  Luke T. Shumaker <lukeshu@lukeshu.com>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+#ifndef _LIBHW_RP2040_HWALARM_H_
+#define _LIBHW_RP2040_HWALARM_H_
+
+#include <stdbool.h>         /* for bool */
+#include <stdint.h>          /* for uint{n}_t */
+
+#include <libmisc/private.h> /* for BEGIN_PRIVATE, END_PRIVATE */
+
+/**
+ * The RP2040 has one system "timer" (which we also use for
+ * ./rp2040_bootclock.c) with 4 alarm interrupts.
+ */
+enum rp2040_hwalarm_instance {
+	RP2040_HWALARM_0 = 0,
+	RP2040_HWALARM_1 = 1,
+	RP2040_HWALARM_2 = 2,
+	RP2040_HWALARM_3 = 3,
+	_RP2040_HWALARM_NUM,
+};
+
+struct rp2040_hwalarm_trigger;
+struct rp2040_hwalarm_trigger {
+	BEGIN_PRIVATE(LIBHW_RP2040_HWALARM_H)
+	void                              *alarm;
+	struct rp2040_hwalarm_trigger     *prev, *next;
+
+	uint64_t                           fire_at_us;
+	void                               (*cb)(void *);
+	void                              *cb_arg;
+	END_PRIVATE(LIBHW_RP2040_HWALARM_H)
+};
+
+/**
+ * Returns true on error.
+ *
+ * fire_at_ns must be at most UINT32_MAX µs (72 minutes) in the future
+ * (or an error will be returned).
+ *
+ * If fire_at_ns is in the past, then it will fire immediately.
+ */
+bool rp2040_hwalarm_trigger_init(struct rp2040_hwalarm_trigger *self,
+                                 enum rp2040_hwalarm_instance alarm_num,
+                                 uint64_t                     fire_at_ns,
+                                 void                         (*cb)(void *),
+                                 void                        *cb_arg);
+
+void rp2040_hwalarm_trigger_cancel(struct rp2040_hwalarm_trigger *self);
+
+#endif /* _LIBHW_RP2040_HWALARM_H_ */