feat(power): Initial deep sleep work.

* New ZMK_SLEEP Kconfig symbol to enable the functionality.
* Switch to PORT events that allows wake from deep sleep.
* Initial basic power management policy, with idle ms,
  and ignoring deep sleep if we detect a USB connection.

1 files changed, 69 insertions, 0 deletions

diff --git a/app/src/power.c b/app/src/power.c
new file mode 100644
index 0000000..73b3f12
--- /dev/null
+++ b/app/src/power.c
@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2020 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#include <zephyr.h>
+#include <kernel.h>
+#include <power/power.h>
+
+#include <logging/log.h>
+
+LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
+
+#include <zmk/usb.h>
+#include <zmk/event-manager.h>
+#include <zmk/events/position-state-changed.h>
+#include <zmk/events/sensor-event.h>
+
+static u32_t power_last_uptime;
+
+#define MAX_IDLE_MS CONFIG_ZMK_IDLE_SLEEP_TIMEOUT
+
+bool is_usb_power_present() {
+#ifdef CONFIG_USB
+    enum usb_dc_status_code usb_status = zmk_usb_get_status();
+    switch (usb_status) {
+    case USB_DC_DISCONNECTED:
+    case USB_DC_UNKNOWN:
+        return false;
+    default:
+        return true;
+    }
+#else
+    return false;
+#endif /* CONFIG_USB */
+}
+
+enum power_states sys_pm_policy_next_state(s32_t ticks) {
+#ifdef CONFIG_SYS_POWER_DEEP_SLEEP_STATES
+#ifdef CONFIG_HAS_SYS_POWER_STATE_DEEP_SLEEP_1
+    s32_t current = k_uptime_get();
+    if (power_last_uptime > 0 && !is_usb_power_present() &&
+        current - power_last_uptime > MAX_IDLE_MS) {
+        return SYS_POWER_STATE_DEEP_SLEEP_1;
+    }
+#endif /* CONFIG_HAS_SYS_POWER_STATE_DEEP_SLEEP_1 */
+#endif /* CONFIG_SYS_POWER_DEEP_SLEEP_STATES */
+
+    return SYS_POWER_STATE_ACTIVE;
+}
+
+int power_event_listener(const struct zmk_event_header *eh) {
+    power_last_uptime = k_uptime_get();
+
+    return 0;
+}
+
+int power_init() {
+    power_last_uptime = k_uptime_get();
+
+    return 0;
+}
+
+ZMK_LISTENER(power, power_event_listener);
+ZMK_SUBSCRIPTION(power, position_state_changed);
+ZMK_SUBSCRIPTION(power, sensor_event);
+
+SYS_INIT(power_init, APPLICATION, CONFIG_APPLICATION_INIT_PRIORITY);
\ No newline at end of file