danos/library/protocol/power/power-protocol.zig

69 lines
2.4 KiB
Zig

//! The power protocol (docs/power.md): system power's domain-named surface,
//! registered under `ServiceId.power`. On x86 the acpi service serves it; on
//! ARM a PSCI/mailbox service will register the same id — subscribers never
//! learn which firmware they are on (docs/discovery.md — firmware neutrality).
//! The vfs-protocol pattern: extern-struct messages, a version, reserved fields.
/// The protocol version a client states nowhere yet — reserved for the day a
/// handshake needs it; requests carry it so a mismatch can be refused loudly.
pub const version: u16 = 1;
pub const Operation = enum(u8) {
/// Subscribe to power events: the subscriber's endpoint rides as the
/// call's capability (the input/device-manager pattern); events arrive on
/// it as buffered messages carrying an `EventMessage`.
subscribe = 1,
/// Orderly shutdown's last step: enter S5. Accepted only from PID 1
/// (init) — the process that has already run the stop sequence over
/// everything else.
shutdown = 2,
/// The published event payload (never sent *to* the service).
event = 3,
};
/// What happened. The vocabulary is hardware-neutral: a lid is a lid whether
/// ACPI or a PSCI mailbox reported it.
pub const Event = enum(u8) {
power_button = 1,
lid = 2,
ac = 3,
battery = 4,
/// A device notification that maps to none of the named events — the
/// `code` and `hid` fields say which device and what code.
notify = 5,
};
pub const Subscribe = extern struct {
operation: u8 = @intFromEnum(Operation.subscribe),
reserved0: u8 = 0,
version: u16 = version,
reserved1: u32 = 0,
};
pub const Shutdown = extern struct {
operation: u8 = @intFromEnum(Operation.shutdown),
reserved0: u8 = 0,
version: u16 = version,
reserved1: u32 = 0,
};
/// A published event, as the buffered-message payload subscribers receive.
pub const EventMessage = extern struct {
operation: u8 = @intFromEnum(Operation.event),
/// An Event value.
event: u8,
reserved0: u16 = 0,
/// The device notification code (Notify's second argument), or 0.
code: u32 = 0,
/// The notifying device's hardware id (EISA-decoded), or all zero.
hid: [8]u8 = .{0} ** 8,
};
pub const Reply = extern struct {
status: i32,
reserved: u32 = 0,
};
/// Upper bound on any message in this protocol — sizes endpoint buffers.
pub const message_maximum = 64;