1 /* 2 * Copyright (C) 2017 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 #ifndef __CROS_EC_INCLUDE_APPLICATION_H 17 #define __CROS_EC_INCLUDE_APPLICATION_H 18 #include <stdint.h> 19 20 #ifdef __cplusplus 21 extern "C" { 22 #endif 23 24 #ifndef __packed 25 #define __packed __attribute__((packed)) 26 #endif 27 28 typedef const void * const __private; 29 30 /* 31 * Typical applications are independent tasks which are directed (or at least 32 * influenced) by some off-chip program. Communications with the applications 33 * are initiated by that off-chip Master and are routed to the application 34 * using a variety of methods. 35 */ 36 37 /****************************************************************************/ 38 /* 39 * Datagram API: 40 * 41 * Nugget OS abstracts the bus protocol (SPI, USB, whatever) into two 42 * unidirectional "datagram" transactions: 43 * 44 * - Read (the master wants data from the application) 45 * - Write (the master sends data to the application) 46 * 47 * Each transaction consists of a four-byte Command from the Master, plus zero 48 * or more data bytes either to (Read) or from (Write) the Master. 49 * 50 * The Command indicates the direction of data transfer, the application it 51 * addresses, and various other parameters. The application is responsible for 52 * providing (Read) or accepting (Write) the data bytes. 53 * 54 * Note: This interface was first used on the SPI bus, which allows for 55 * simultaneous bidirectional data transfer. We limit this interface to 56 * unidirectional transfers, because none of the other buses support that 57 * feature. 58 */ 59 60 /****************************************************************************/ 61 /* Application IDs */ 62 63 /* These two App IDs shouldn't be changed or used for other purposes */ 64 #define APP_ID_NUGGET 0x00 /* because we're selfish */ 65 #define APP_ID_TPM_REGISTER_API 0xD4 /* mandated by the TCG */ 66 /* 67 * Other App IDs are defined here. It will help avoid confusion if you use only 68 * the values from here and don't change them once they're set. But it's up to 69 * you. I'm a comment, not a cop. 70 */ 71 #define APP_ID_AVB 0x01 72 #define APP_ID_KEYMASTER 0x02 73 #define APP_ID_WEAVER 0x03 74 #define APP_ID_PROTOBUF 0x04 75 76 /* Fake apps used only for testing */ 77 #define APP_ID_AVB_TEST 0x11 78 79 /* This app ID should only be used by tests. */ 80 #define APP_ID_TEST 0xff 81 82 /****************************************************************************/ 83 /* Other command fields */ 84 85 /* 86 * The Command encoding is: 87 * 88 * Bits 31-24 Control flags (reserved) 89 * Bits 23-16 Application ID 90 * Bits 15-0 Parameters (application-specific) 91 */ 92 93 /* Control flag bits */ 94 #define CMD_IS_READ 0x80000000 /* 1=Read, 0=Write */ 95 /* All other control flags bits are reserved */ 96 97 /* Extracting fields from a command */ 98 #define GET_APP_ID(cmd) (((cmd) & 0x00ff0000) >> 16) 99 #define GET_APP_PARAM(cmd) ((cmd) & 0x0000ffff) 100 101 /* Specifying command fields */ 102 #define CMD_ID(id) (((id) & 0x000000ff) << 16) 103 #define CMD_PARAM(p) ((p) & 0x0000ffff) 104 #define CMD_SET_PARAM(cmd, p) cmd = ((cmd & 0xffff0000) | (p & 0x0000ffff)) 105 106 /****************************************************************************/ 107 /* Data transfer */ 108 109 /* 110 * Functions of this type are invoked when the Master wants to read bytes from 111 * an application. The app should parse the Command, copy up to max_tx_size 112 * bytes into the tx_buffer provided, and return the number of bytes to send 113 * back to the Master. 114 * 115 * This is called in interrupt context, so act quickly. 116 * 117 * The last arg is for internal use. Just ignore it. 118 */ 119 typedef uint32_t (read_from_app_fn_t)(uint32_t command, 120 uint8_t *tx_buffer, 121 uint32_t max_tx_bytes, 122 __private priv); 123 124 /* 125 * Functions of this type are invoked when the Master has sent bytes to the 126 * application. The app should parse the Command and copy or process the 127 * expected number of bytes in the rx_buffer that the master has sent, up to 128 * rx_num_bytes. 129 * 130 * NOTE: Due to a quirk of the Citadel hardware, up to four extra bytes from 131 * the *next* transaction may be at the end of the rx_buffer. The application 132 * should only poke at the bytes it expects to see and ignore any extras. 133 * 134 * This is called in interrupt context, so act quickly. 135 * 136 * The last arg is for internal use. Just ignore it. 137 */ 138 typedef void (write_to_app_fn_t)(uint32_t command, 139 const uint8_t *rx_buffer, 140 uint32_t num_rx_bytes, 141 __private priv); 142 143 /* 144 * For apps that run asynchronously with little oversight, occasional 145 * Read/Write operations may be all that's necessary. An app that intercepts 146 * button presses, an accelerometer, or a fingerprint scanner can simply be 147 * told to start or stop and will send interrupts to the Master when its 148 * attention is required. 149 * 150 * Applications are free to define their own protcols and APIs using only the 151 * functions and constants above (and at least one app does just that). 152 * 153 * An app that wishes to handle its messaging using only the components 154 * described to this point would use the following macro to declare itself. 155 */ 156 157 /** 158 * This registers an application that communicates using the Datagram API, 159 * which deals only with the raw byte streams between Master (AP) and Slave 160 * (application). 161 * 162 * The name and version values may be exported to the Master by Nugget OS, so 163 * the Master can query what applications are available without blindly trying 164 * them all to see what works. 165 * 166 * @param Id The Application ID, defined above 167 * @param Name A human-readable string identifying the application 168 * @param Version An app-specific uint32_t number, for compability purposes 169 * @param From_fn A pointer to the app's read_from_app_fnt_t handler 170 * @param To_fn A pointer to the app's write_to_app_fn_t handler 171 */ 172 #define DECLARE_APPLICATION_DATAGRAM(Id, Name, Version, From_fn, To_fn) \ 173 const struct app_info __keep CONCAT2(app_, Id) \ 174 __attribute__((section(".rodata.app_info"))) \ 175 = { .api = { .id = Id, \ 176 .from_fn = From_fn, .to_fn = To_fn}, \ 177 .version = Version, .name = Name } 178 179 /****************************************************************************/ 180 /* Transport API */ 181 /* 182 * Rather than handle unidirectonal datagrams themselves, many applications 183 * want to implement a request/response behavior, where the Master tells the 184 * app to do something and waits for it to finish and return the result. 185 * 186 * Seen from the AP's side, the application would be invoked using a blocking 187 * function something like this: 188 * 189 * uint32_t call_application(uint8_t app_id, uint16_t app_param, 190 * const uint8_t *args, uint16_t arg_len, 191 * uint8_t *reply, uint16_t *reply_len); 192 * 193 * The request or response may be larger than one bus transaction, and the AP 194 * may poll until the app finishes or wait for an interrupt before retrieving 195 * the reply (there's no difference from app's point of view). 196 * 197 * With this API, the application is initially idle. Nugget OS will marshall 198 * all the input from the Master before waking the application. The Application 199 * then performs the requested operation and transititions to a "done" state. 200 * The Master will retrieve the application status and any reply data from 201 * Nugget OS, after which the application is ready to handle the next command. 202 * 203 * Applications that wish to use this transport API will need to declare a 204 * private struct app_transport which Nugget OS can use to maintain the state: 205 */ 206 207 struct app_transport { 208 uint32_t command; /* from master */ 209 volatile uint32_t status; /* current application status */ 210 uint8_t *request, *response; /* input/output data buffer */ 211 uint16_t max_request_len, max_response_len; /* data buffer sizes */ 212 uint16_t request_len, response_len; /* current buffer count */ 213 uint16_t request_idx, response_idx; /* used internally */ 214 void (*done_fn)(struct app_transport *); /* optional cleanup function */ 215 /* Note: Any done_fn() is called in interrupt context. Be quick. */ 216 }; 217 218 /* 219 * TODO(b/66104849): Note that request and response buffers are transferred as 220 * byte streams. However, if they will eventually represent structs, the usual 221 * ABI alignment requirements will be required. Until we've declared all 222 * applications structs in a union, we will need to align the buffers manually. 223 * Use this to declare the uint8_t buffers until then: 224 */ 225 #define __TRANSPORT_ALIGNED__ __attribute__((aligned(8))) 226 227 /* For debugging if needed */ 228 extern void dump_transport_state(const struct app_transport *s); 229 230 /* 231 * The application will need to provide a write_to_app_fn_t function that will 232 * be invoked when a new request is ready to be processed. All command and data 233 * parameters will already be present in the app's struct app_transport, so it 234 * just needs to awaken the application task to do the work. 235 * 236 * When processing is finished, the app should call the app_reply() function to 237 * return its status code and specify length of any data it has placed into the 238 * response buffer, and then it can go back to sleep until its next invocation. 239 */ 240 void app_reply(struct app_transport *st, uint32_t status, uint16_t reply_len); 241 242 /* Application status codes are uint32_t, but an enum is easier to read. */ 243 enum app_status { 244 /* A few values are common to all applications */ 245 APP_SUCCESS = 0, 246 APP_ERROR_BOGUS_ARGS, /* caller being stupid */ 247 APP_ERROR_INTERNAL, /* application being stupid */ 248 APP_ERROR_TOO_MUCH, /* caller sent too much data */ 249 APP_ERROR_IO, /* problem sending or receiving data */ 250 APP_ERROR_RPC, /* problem during RPC communication */ 251 /* more? */ 252 253 APP_SPECIFIC_ERROR = 0x20, /* "should be enough for anybody" */ 254 /* App-specific error codes can use APP_SPECIFIC_ERROR+0, +1, +2, ... */ 255 256 /* For debugging, returning a line number might be helpful */ 257 APP_LINE_NUMBER_BASE = 0x70000000, 258 #define APP_ERROR_LINENO (APP_LINE_NUMBER_BASE + __LINE__) 259 260 /* Bit 31 is reserved for internal use */ 261 MAX_APP_STATUS = 0x7fffffff, 262 }; 263 264 /** 265 * This registers an application that communicates using the Transport API. 266 * 267 * The name and version values may be exported to the Master by Nugget OS, so 268 * the Master can query what applications are available without blindly trying 269 * them all to see what works. 270 * 271 * @param Id The Application ID, defined above 272 * @param Name A human-readable string identifying the application 273 * @param Version An app-specific uint32_t number, for compability purposes 274 * @param State A pointer to the app's struct app_transport 275 * @param To_fn A pointer to the app's write_to_app_fn_t handler 276 */ 277 #define DECLARE_APPLICATION_TRANSPORT(Id, Name, Version, State, To_fn) \ 278 const struct app_info __keep CONCAT2(app_, Id) \ 279 __attribute__((section(".rodata.app_info"))) \ 280 = { .api = { .id = Id, \ 281 .from_fn = transaction_api_from_fn, \ 282 .to_fn = transaction_api_to_fn, \ 283 .data = &(const struct datagram_api) \ 284 { .id = Id, .to_fn = To_fn, \ 285 .data = State } }, \ 286 .version = Version, .name = Name } 287 288 /****************************************************************************/ 289 /* Pay no attention to that man behind the curtain */ 290 291 /* We'll allow 31 bits of application status. We need one bit for transport. */ 292 #define APP_STATUS_IDLE 0x00000000 /* waiting for instructions */ 293 #define APP_STATUS_DONE 0x80000000 /* finished, reply is ready */ 294 #define APP_STATUS_CODE(res) ((res) & 0x7fffffff) /* actual status */ 295 296 /* Datagram API needs this info */ 297 struct datagram_api { 298 uint8_t id; 299 read_from_app_fn_t * const from_fn; 300 write_to_app_fn_t * const to_fn; 301 const void * const data; 302 }; 303 304 /* Here's the struct that keeps track of registered applications */ 305 struct app_info { 306 struct datagram_api api; 307 uint32_t version; 308 const char * const name; 309 }; 310 311 /* These handle the Transport API */ 312 extern read_from_app_fn_t transaction_api_from_fn; 313 extern write_to_app_fn_t transaction_api_to_fn; 314 315 /* Command flags used internally by Transport API messages */ 316 #define CMD_TRANSPORT 0x40000000 /* 1=Transport API message */ 317 #define CMD_IS_DATA 0x20000000 /* 1=data msg 0=status msg */ 318 #define CMD_MORE_TO_COME 0x10000000 /* 1=continued 0=new */ 319 320 #ifdef __cplusplus 321 } 322 #endif 323 324 #endif /* __CROS_EC_INCLUDE_APPLICATION_H */ 325