1 /* 2 * Copyright (c) 2022 Google LLC 3 * 4 * SPDX-License-Identifier: Apache-2.0 5 */ 6 7 #ifndef ZEPHYR_SUBSYS_MGMT_EC_HOST_CMD_BACKENDS_EC_HOST_CMD_BACKEND_SHI_H_ 8 #define ZEPHYR_SUBSYS_MGMT_EC_HOST_CMD_BACKENDS_EC_HOST_CMD_BACKEND_SHI_H_ 9 10 #include <zephyr/device.h> 11 12 /* 13 * Byte codes returned by EC over SPI interface. 14 * 15 * These can be used by the AP to debug the EC interface, and to determine 16 * when the EC is not in a state where it will ever get around to responding 17 * to the AP. 18 * 19 * Example of sequence of bytes read from EC for a current good transfer: 20 * 1. - - AP asserts chip select (CS#) 21 * 2. EC_SHI_OLD_READY - AP sends first byte(s) of request 22 * 3. - - EC starts handling CS# interrupt 23 * 4. EC_SHI_RECEIVING - AP sends remaining byte(s) of request 24 * 5. EC_SHI_PROCESSING - EC starts processing request; AP is clocking in 25 * bytes looking for EC_SHI_FRAME_START 26 * 6. - - EC finishes processing and sets up response 27 * 7. EC_SHI_FRAME_START - AP reads frame byte 28 * 8. (response packet) - AP reads response packet 29 * 9. EC_SHI_PAST_END - Any additional bytes read by AP 30 * 10 - - AP deasserts chip select 31 * 11 - - EC processes CS# interrupt and sets up DMA for 32 * next request 33 * 34 * If the AP is waiting for EC_SHI_FRAME_START and sees any value other than 35 * the following byte values: 36 * EC_SHI_OLD_READY 37 * EC_SHI_RX_READY 38 * EC_SHI_RECEIVING 39 * EC_SHI_PROCESSING 40 * 41 * Then the EC found an error in the request, or was not ready for the request 42 * and lost data. The AP should give up waiting for EC_SHI_FRAME_START, 43 * because the EC is unable to tell when the AP is done sending its request. 44 */ 45 46 /* 47 * Framing byte which precedes a response packet from the EC. After sending a 48 * request, the AP will clock in bytes until it sees the framing byte, then 49 * clock in the response packet. 50 */ 51 #define EC_SHI_FRAME_START 0xec 52 53 /* 54 * Padding bytes which are clocked out after the end of a response packet. 55 */ 56 #define EC_SHI_PAST_END 0xed 57 58 /* 59 * EC is ready to receive, and has ignored the byte sent by the AP. EC expects 60 * that the AP will send a valid packet header (starting with 61 * EC_COMMAND_PROTOCOL_3) in the next 32 bytes. 62 * 63 * NOTE: Some SPI configurations place the Most Significant Bit on SDO when 64 * CS goes low. This macro has the Most Significant Bit set to zero, 65 * so SDO will not be driven high when CS goes low. 66 */ 67 #define EC_SHI_RX_READY 0x78 68 69 /* 70 * EC has started receiving the request from the AP, but hasn't started 71 * processing it yet. 72 */ 73 #define EC_SHI_RECEIVING 0xf9 74 75 /* EC has received the entire request from the AP and is processing it. */ 76 #define EC_SHI_PROCESSING 0xfa 77 78 /* 79 * EC received bad data from the AP, such as a packet header with an invalid 80 * length. EC will ignore all data until chip select deasserts. 81 */ 82 #define EC_SHI_RX_BAD_DATA 0xfb 83 84 /* 85 * EC received data from the AP before it was ready. That is, the AP asserted 86 * chip select and started clocking data before the EC was ready to receive it. 87 * EC will ignore all data until chip select deasserts. 88 */ 89 #define EC_SHI_NOT_READY 0xfc 90 91 /* 92 * EC was ready to receive a request from the AP. EC has treated the byte sent 93 * by the AP as part of a request packet, or (for old-style ECs) is processing 94 * a fully received packet but is not ready to respond yet. 95 */ 96 #define EC_SHI_OLD_READY 0xfd 97 98 /* Supported version of host commands protocol. */ 99 #define EC_HOST_REQUEST_VERSION 3 100 101 #endif /* ZEPHYR_SUBSYS_MGMT_EC_HOST_CMD_BACKENDS_EC_HOST_CMD_BACKEND_SHI_H_ */ 102
