Import of the watch repository from Pebble

src/fw/drivers/accessory.h

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+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#include "services/common/system_task.h"
+
+//! Different speeds we support running the accessory connector at.
+//!
+//! @internal
+//! Please keep this enum in order from lowest speed to highest.
+typedef enum {
+  AccessoryBaud9600,
+  AccessoryBaud14400,
+  AccessoryBaud19200,
+  AccessoryBaud28800,
+  AccessoryBaud38400,
+  AccessoryBaud57600,
+  AccessoryBaud62500,
+  AccessoryBaud115200,
+  AccessoryBaud125000,
+  AccessoryBaud230400,
+  AccessoryBaud250000,
+  AccessoryBaud460800,
+  AccessoryBaud921600,
+
+  AccessoryBaudInvalid
+} AccessoryBaud;
+
+//! The type of function used for ISR-based sending via accessory_send_stream(). This function MUST
+//! send a single byte by calling accessory_send_byte() and/or return false to indicate that there
+//! is no more data to be sent.
+typedef bool (*AccessoryDataStreamCallback)(void *context);
+
+//! Initialize the accessory driver
+void accessory_init(void);
+
+//! Blocks the accessory port from being used
+void accessory_block(void);
+
+//! Unblocks the accessory port and allows it to be used
+void accessory_unblock(void);
+
+//! Enable power output on the accessory connector.
+void accessory_set_power(bool on);
+
+//! Send a single byte synchronously out the accessory connector. Input must be disabled before
+//! calling this function.
+void accessory_send_byte(uint8_t data);
+
+//! Send data synchronously out the accessory connector. Will return once all data has been sent.
+void accessory_send_data(const uint8_t *data, size_t length);
+
+//! Sends data using ISRs by calling the provided function to send the next byte until the stream
+//! callback returns false to indicate sending is complete or bus contention is detected
+bool accessory_send_stream(AccessoryDataStreamCallback stream_callback, void *context);
+
+//! Stops any ISR-based sending which is in progress
+void accessory_send_stream_stop(void);
+
+//! Stop the driver from reading any input on the accessory port. When input is disabled we can
+//! write out the accessory port at higher rates as we don't have to worry about supressing
+//! reading back our own output.
+void accessory_disable_input(void);
+
+//! Allow the driver to start receiving input again. Only valid after calling
+//! accessory_disable_input.
+void accessory_enable_input(void);
+
+//! Set the baudrate
+void accessory_set_baudrate(AccessoryBaud baud_select);
+
+//! Called from the accessory UART interrupt. The manager is responsible for implementing this
+//! function.
+//! @return whether we need to trigger a context switch based on handling this character
+bool accessory_manager_handle_character_from_isr(char c);
+
+//! Called from the accessory UART interrupt. The manager is responsible for implementing this
+//! function.
+//! @return whether we need to trigger a context switch based on handling this character
+bool accessory_manager_handle_break_from_isr(void);
+
+//! Returns whether or not there has been bus contention detected since accessory_disable_input()
+//! was last called.
+bool accessory_bus_contention_detected(void);
+
+//! Checks if the pull-up resistor which is required for smarstraps is present
+bool accessory_is_present(void);
+
+//! Uses DMA for receiving from the peripheral
+void accessory_use_dma(bool use_dma);