1 // Copyright 2023 The Pigweed Authors 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); you may not 4 // use this file except in compliance with the License. You may obtain a copy of 5 // the License at 6 // 7 // https://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 11 // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 12 // License for the specific language governing permissions and limitations under 13 // the License. 14 15 #pragma once 16 17 #include <utility> 18 19 #include "pw_bytes/span.h" 20 #include "pw_function/function.h" 21 #include "pw_status/status.h" 22 23 namespace pw::spi { 24 25 // The Responder class provides an abstract interface used to receive and 26 // transmit data on the responder side of a SPI bus. 27 class Responder { 28 public: 29 virtual ~Responder() = default; 30 31 // Set `callback` to be called when SPI transaction completes. `callback` can 32 // be called in an interrupt context. `callback` should not be changed during 33 // execution of a completion. 34 // 35 // A value of CANCELLED for the Status parameter indicates Cancel() was 36 // called. Partially transferred data may be passed in that case as well. 37 // Other Status values are implementer defined. SetCompletionHandler(Function<void (ByteSpan,Status)> callback)38 void SetCompletionHandler(Function<void(ByteSpan, Status)> callback) { 39 DoSetCompletionHandler(std::move(callback)); 40 } 41 42 // `tx_data` is queued for tx when called, but only transmitted when 43 // the initiator starts the next transaction. It's up to the implementer to 44 // define how stuffing bytes are handled. 45 // `rx_data` is populated as the initiator transfers data. A slice of 46 // `rx_data` is passed as a span to the completion callback. 47 // 48 // Only one outstanding request should be active. UNAVAILABLE will be returned 49 // if a transaction is already established. 50 // 51 // The completion handler will always be invoked, even in the case of an 52 // Cancel(). In that case a Status value of CANCELLED will be passed. WriteReadAsync(ConstByteSpan tx_data,ByteSpan rx_data)53 Status WriteReadAsync(ConstByteSpan tx_data, ByteSpan rx_data) { 54 return DoWriteReadAsync(tx_data, rx_data); 55 } 56 57 // Cancel the outstanding `WriteReadAsync` call. The completion handler will 58 // be called with a Status of CANCELLED after this is called. Cancel()59 void Cancel() { DoCancel(); } 60 61 private: 62 virtual void DoSetCompletionHandler( 63 Function<void(ByteSpan, Status)> callback) = 0; 64 virtual Status DoWriteReadAsync(ConstByteSpan tx_data, ByteSpan rx_data) = 0; 65 virtual void DoCancel() = 0; 66 }; 67 68 } // namespace pw::spi 69