1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Beagleplay Linux Driver for Greybus 4 * 5 * Copyright (c) 2023 Ayush Singh <ayushdevel1325@gmail.com> 6 * Copyright (c) 2023 BeagleBoard.org Foundation 7 */ 8 9 #include <linux/gfp.h> 10 #include <linux/greybus.h> 11 #include <linux/module.h> 12 #include <linux/of.h> 13 #include <linux/printk.h> 14 #include <linux/serdev.h> 15 #include <linux/tty.h> 16 #include <linux/tty_driver.h> 17 #include <linux/greybus/hd.h> 18 #include <linux/init.h> 19 #include <linux/device.h> 20 #include <linux/crc-ccitt.h> 21 #include <linux/circ_buf.h> 22 #include <linux/types.h> 23 #include <linux/workqueue.h> 24 25 #define RX_HDLC_PAYLOAD 256 26 #define CRC_LEN 2 27 #define MAX_RX_HDLC (1 + RX_HDLC_PAYLOAD + CRC_LEN) 28 #define TX_CIRC_BUF_SIZE 1024 29 30 #define ADDRESS_GREYBUS 0x01 31 #define ADDRESS_DBG 0x02 32 #define ADDRESS_CONTROL 0x03 33 34 #define HDLC_FRAME 0x7E 35 #define HDLC_ESC 0x7D 36 #define HDLC_XOR 0x20 37 38 #define CONTROL_SVC_START 0x01 39 #define CONTROL_SVC_STOP 0x02 40 41 /* The maximum number of CPorts supported by Greybus Host Device */ 42 #define GB_MAX_CPORTS 32 43 44 /** 45 * struct gb_beagleplay - BeaglePlay Greybus driver 46 * 47 * @sd: underlying serdev device 48 * 49 * @gb_hd: greybus host device 50 * 51 * @tx_work: hdlc transmit work 52 * @tx_producer_lock: hdlc transmit data producer lock. acquired when appending data to buffer. 53 * @tx_consumer_lock: hdlc transmit data consumer lock. acquired when sending data over uart. 54 * @tx_circ_buf: hdlc transmit circular buffer. 55 * @tx_crc: hdlc transmit crc-ccitt fcs 56 * 57 * @rx_buffer_len: length of receive buffer filled. 58 * @rx_buffer: hdlc frame receive buffer 59 * @rx_in_esc: hdlc rx flag to indicate ESC frame 60 */ 61 struct gb_beagleplay { 62 struct serdev_device *sd; 63 64 struct gb_host_device *gb_hd; 65 66 struct work_struct tx_work; 67 spinlock_t tx_producer_lock; 68 spinlock_t tx_consumer_lock; 69 struct circ_buf tx_circ_buf; 70 u16 tx_crc; 71 72 u16 rx_buffer_len; 73 bool rx_in_esc; 74 u8 rx_buffer[MAX_RX_HDLC]; 75 }; 76 77 /** 78 * struct hdlc_payload - Structure to represent part of HDCL frame payload data. 79 * 80 * @len: buffer length in bytes 81 * @buf: payload buffer 82 */ 83 struct hdlc_payload { 84 u16 len; 85 void *buf; 86 }; 87 88 /** 89 * struct hdlc_greybus_frame - Structure to represent greybus HDLC frame payload 90 * 91 * @cport: cport id 92 * @hdr: greybus operation header 93 * @payload: greybus message payload 94 * 95 * The HDLC payload sent over UART for greybus address has cport preappended to greybus message 96 */ 97 struct hdlc_greybus_frame { 98 __le16 cport; 99 struct gb_operation_msg_hdr hdr; 100 u8 payload[]; 101 } __packed; 102 103 static void hdlc_rx_greybus_frame(struct gb_beagleplay *bg, u8 *buf, u16 len) 104 { 105 struct hdlc_greybus_frame *gb_frame = (struct hdlc_greybus_frame *)buf; 106 u16 cport_id = le16_to_cpu(gb_frame->cport); 107 u16 gb_msg_len = le16_to_cpu(gb_frame->hdr.size); 108 109 dev_dbg(&bg->sd->dev, "Greybus Operation %u type %X cport %u status %u received", 110 gb_frame->hdr.operation_id, gb_frame->hdr.type, cport_id, gb_frame->hdr.result); 111 112 greybus_data_rcvd(bg->gb_hd, cport_id, (u8 *)&gb_frame->hdr, gb_msg_len); 113 } 114 115 static void hdlc_rx_dbg_frame(const struct gb_beagleplay *bg, const char *buf, u16 len) 116 { 117 dev_dbg(&bg->sd->dev, "CC1352 Log: %.*s", (int)len, buf); 118 } 119 120 /** 121 * hdlc_write() - Consume HDLC Buffer. 122 * @bg: beagleplay greybus driver 123 * 124 * Assumes that consumer lock has been acquired. 125 */ 126 static void hdlc_write(struct gb_beagleplay *bg) 127 { 128 int written; 129 /* Start consuming HDLC data */ 130 int head = smp_load_acquire(&bg->tx_circ_buf.head); 131 int tail = bg->tx_circ_buf.tail; 132 int count = CIRC_CNT_TO_END(head, tail, TX_CIRC_BUF_SIZE); 133 const unsigned char *buf = &bg->tx_circ_buf.buf[tail]; 134 135 if (count > 0) { 136 written = serdev_device_write_buf(bg->sd, buf, count); 137 138 /* Finish consuming HDLC data */ 139 smp_store_release(&bg->tx_circ_buf.tail, (tail + written) & (TX_CIRC_BUF_SIZE - 1)); 140 } 141 } 142 143 /** 144 * hdlc_append() - Queue HDLC data for sending. 145 * @bg: beagleplay greybus driver 146 * @value: hdlc byte to transmit 147 * 148 * Assumes that producer lock as been acquired. 149 */ 150 static void hdlc_append(struct gb_beagleplay *bg, u8 value) 151 { 152 int tail, head = bg->tx_circ_buf.head; 153 154 while (true) { 155 tail = READ_ONCE(bg->tx_circ_buf.tail); 156 157 if (CIRC_SPACE(head, tail, TX_CIRC_BUF_SIZE) >= 1) { 158 bg->tx_circ_buf.buf[head] = value; 159 160 /* Finish producing HDLC byte */ 161 smp_store_release(&bg->tx_circ_buf.head, 162 (head + 1) & (TX_CIRC_BUF_SIZE - 1)); 163 return; 164 } 165 dev_warn(&bg->sd->dev, "Tx circ buf full"); 166 usleep_range(3000, 5000); 167 } 168 } 169 170 static void hdlc_append_escaped(struct gb_beagleplay *bg, u8 value) 171 { 172 if (value == HDLC_FRAME || value == HDLC_ESC) { 173 hdlc_append(bg, HDLC_ESC); 174 value ^= HDLC_XOR; 175 } 176 hdlc_append(bg, value); 177 } 178 179 static void hdlc_append_tx_frame(struct gb_beagleplay *bg) 180 { 181 bg->tx_crc = 0xFFFF; 182 hdlc_append(bg, HDLC_FRAME); 183 } 184 185 static void hdlc_append_tx_u8(struct gb_beagleplay *bg, u8 value) 186 { 187 bg->tx_crc = crc_ccitt(bg->tx_crc, &value, 1); 188 hdlc_append_escaped(bg, value); 189 } 190 191 static void hdlc_append_tx_buf(struct gb_beagleplay *bg, const u8 *buf, u16 len) 192 { 193 size_t i; 194 195 for (i = 0; i < len; i++) 196 hdlc_append_tx_u8(bg, buf[i]); 197 } 198 199 static void hdlc_append_tx_crc(struct gb_beagleplay *bg) 200 { 201 bg->tx_crc ^= 0xffff; 202 hdlc_append_escaped(bg, bg->tx_crc & 0xff); 203 hdlc_append_escaped(bg, (bg->tx_crc >> 8) & 0xff); 204 } 205 206 static void hdlc_transmit(struct work_struct *work) 207 { 208 struct gb_beagleplay *bg = container_of(work, struct gb_beagleplay, tx_work); 209 210 spin_lock_bh(&bg->tx_consumer_lock); 211 hdlc_write(bg); 212 spin_unlock_bh(&bg->tx_consumer_lock); 213 } 214 215 static void hdlc_tx_frames(struct gb_beagleplay *bg, u8 address, u8 control, 216 const struct hdlc_payload payloads[], size_t count) 217 { 218 size_t i; 219 220 spin_lock(&bg->tx_producer_lock); 221 222 hdlc_append_tx_frame(bg); 223 hdlc_append_tx_u8(bg, address); 224 hdlc_append_tx_u8(bg, control); 225 226 for (i = 0; i < count; ++i) 227 hdlc_append_tx_buf(bg, payloads[i].buf, payloads[i].len); 228 229 hdlc_append_tx_crc(bg); 230 hdlc_append_tx_frame(bg); 231 232 spin_unlock(&bg->tx_producer_lock); 233 234 schedule_work(&bg->tx_work); 235 } 236 237 static void hdlc_tx_s_frame_ack(struct gb_beagleplay *bg) 238 { 239 hdlc_tx_frames(bg, bg->rx_buffer[0], (bg->rx_buffer[1] >> 1) & 0x7, NULL, 0); 240 } 241 242 static void hdlc_rx_frame(struct gb_beagleplay *bg) 243 { 244 u16 crc, len; 245 u8 ctrl, *buf; 246 u8 address = bg->rx_buffer[0]; 247 248 crc = crc_ccitt(0xffff, bg->rx_buffer, bg->rx_buffer_len); 249 if (crc != 0xf0b8) { 250 dev_warn_ratelimited(&bg->sd->dev, "CRC failed from %02x: 0x%04x", address, crc); 251 return; 252 } 253 254 ctrl = bg->rx_buffer[1]; 255 buf = &bg->rx_buffer[2]; 256 len = bg->rx_buffer_len - 4; 257 258 /* I-Frame, send S-Frame ACK */ 259 if ((ctrl & 1) == 0) 260 hdlc_tx_s_frame_ack(bg); 261 262 switch (address) { 263 case ADDRESS_DBG: 264 hdlc_rx_dbg_frame(bg, buf, len); 265 break; 266 case ADDRESS_GREYBUS: 267 hdlc_rx_greybus_frame(bg, buf, len); 268 break; 269 default: 270 dev_warn_ratelimited(&bg->sd->dev, "unknown frame %u", address); 271 } 272 } 273 274 static ssize_t hdlc_rx(struct gb_beagleplay *bg, const u8 *data, size_t count) 275 { 276 size_t i; 277 u8 c; 278 279 for (i = 0; i < count; ++i) { 280 c = data[i]; 281 282 switch (c) { 283 case HDLC_FRAME: 284 if (bg->rx_buffer_len) 285 hdlc_rx_frame(bg); 286 287 bg->rx_buffer_len = 0; 288 break; 289 case HDLC_ESC: 290 bg->rx_in_esc = true; 291 break; 292 default: 293 if (bg->rx_in_esc) { 294 c ^= 0x20; 295 bg->rx_in_esc = false; 296 } 297 298 if (bg->rx_buffer_len < MAX_RX_HDLC) { 299 bg->rx_buffer[bg->rx_buffer_len] = c; 300 bg->rx_buffer_len++; 301 } else { 302 dev_err_ratelimited(&bg->sd->dev, "RX Buffer Overflow"); 303 bg->rx_buffer_len = 0; 304 } 305 } 306 } 307 308 return count; 309 } 310 311 static int hdlc_init(struct gb_beagleplay *bg) 312 { 313 INIT_WORK(&bg->tx_work, hdlc_transmit); 314 spin_lock_init(&bg->tx_producer_lock); 315 spin_lock_init(&bg->tx_consumer_lock); 316 bg->tx_circ_buf.head = 0; 317 bg->tx_circ_buf.tail = 0; 318 319 bg->tx_circ_buf.buf = devm_kmalloc(&bg->sd->dev, TX_CIRC_BUF_SIZE, GFP_KERNEL); 320 if (!bg->tx_circ_buf.buf) 321 return -ENOMEM; 322 323 bg->rx_buffer_len = 0; 324 bg->rx_in_esc = false; 325 326 return 0; 327 } 328 329 static void hdlc_deinit(struct gb_beagleplay *bg) 330 { 331 flush_work(&bg->tx_work); 332 } 333 334 static ssize_t gb_tty_receive(struct serdev_device *sd, const u8 *data, 335 size_t count) 336 { 337 struct gb_beagleplay *bg = serdev_device_get_drvdata(sd); 338 339 return hdlc_rx(bg, data, count); 340 } 341 342 static void gb_tty_wakeup(struct serdev_device *serdev) 343 { 344 struct gb_beagleplay *bg = serdev_device_get_drvdata(serdev); 345 346 schedule_work(&bg->tx_work); 347 } 348 349 static struct serdev_device_ops gb_beagleplay_ops = { 350 .receive_buf = gb_tty_receive, 351 .write_wakeup = gb_tty_wakeup, 352 }; 353 354 /** 355 * gb_message_send() - Send greybus message using HDLC over UART 356 * 357 * @hd: pointer to greybus host device 358 * @cport: AP cport where message originates 359 * @msg: greybus message to send 360 * @mask: gfp mask 361 * 362 * Greybus HDLC frame has the following payload: 363 * 1. le16 cport 364 * 2. gb_operation_msg_hdr msg_header 365 * 3. u8 *msg_payload 366 */ 367 static int gb_message_send(struct gb_host_device *hd, u16 cport, struct gb_message *msg, gfp_t mask) 368 { 369 struct gb_beagleplay *bg = dev_get_drvdata(&hd->dev); 370 struct hdlc_payload payloads[3]; 371 __le16 cport_id = cpu_to_le16(cport); 372 373 dev_dbg(&hd->dev, "Sending greybus message with Operation %u, Type: %X on Cport %u", 374 msg->header->operation_id, msg->header->type, cport); 375 376 if (le16_to_cpu(msg->header->size) > RX_HDLC_PAYLOAD) 377 return dev_err_probe(&hd->dev, -E2BIG, "Greybus message too big"); 378 379 payloads[0].buf = &cport_id; 380 payloads[0].len = sizeof(cport_id); 381 payloads[1].buf = msg->header; 382 payloads[1].len = sizeof(*msg->header); 383 payloads[2].buf = msg->payload; 384 payloads[2].len = msg->payload_size; 385 386 hdlc_tx_frames(bg, ADDRESS_GREYBUS, 0x03, payloads, 3); 387 greybus_message_sent(bg->gb_hd, msg, 0); 388 389 return 0; 390 } 391 392 static void gb_message_cancel(struct gb_message *message) 393 { 394 } 395 396 static struct gb_hd_driver gb_hdlc_driver = { .message_send = gb_message_send, 397 .message_cancel = gb_message_cancel }; 398 399 static void gb_beagleplay_start_svc(struct gb_beagleplay *bg) 400 { 401 const u8 command = CONTROL_SVC_START; 402 const struct hdlc_payload payload = { .len = 1, .buf = (void *)&command }; 403 404 hdlc_tx_frames(bg, ADDRESS_CONTROL, 0x03, &payload, 1); 405 } 406 407 static void gb_beagleplay_stop_svc(struct gb_beagleplay *bg) 408 { 409 const u8 command = CONTROL_SVC_STOP; 410 const struct hdlc_payload payload = { .len = 1, .buf = (void *)&command }; 411 412 hdlc_tx_frames(bg, ADDRESS_CONTROL, 0x03, &payload, 1); 413 } 414 415 static void gb_greybus_deinit(struct gb_beagleplay *bg) 416 { 417 gb_hd_del(bg->gb_hd); 418 gb_hd_put(bg->gb_hd); 419 } 420 421 static int gb_greybus_init(struct gb_beagleplay *bg) 422 { 423 int ret; 424 425 bg->gb_hd = gb_hd_create(&gb_hdlc_driver, &bg->sd->dev, TX_CIRC_BUF_SIZE, GB_MAX_CPORTS); 426 if (IS_ERR(bg->gb_hd)) { 427 dev_err(&bg->sd->dev, "Failed to create greybus host device"); 428 return PTR_ERR(bg->gb_hd); 429 } 430 431 ret = gb_hd_add(bg->gb_hd); 432 if (ret) { 433 dev_err(&bg->sd->dev, "Failed to add greybus host device"); 434 goto free_gb_hd; 435 } 436 dev_set_drvdata(&bg->gb_hd->dev, bg); 437 438 return 0; 439 440 free_gb_hd: 441 gb_greybus_deinit(bg); 442 return ret; 443 } 444 445 static void gb_serdev_deinit(struct gb_beagleplay *bg) 446 { 447 serdev_device_close(bg->sd); 448 } 449 450 static int gb_serdev_init(struct gb_beagleplay *bg) 451 { 452 int ret; 453 454 serdev_device_set_drvdata(bg->sd, bg); 455 serdev_device_set_client_ops(bg->sd, &gb_beagleplay_ops); 456 ret = serdev_device_open(bg->sd); 457 if (ret) 458 return dev_err_probe(&bg->sd->dev, ret, "Unable to open serial device"); 459 460 serdev_device_set_baudrate(bg->sd, 115200); 461 serdev_device_set_flow_control(bg->sd, false); 462 463 return 0; 464 } 465 466 static int gb_beagleplay_probe(struct serdev_device *serdev) 467 { 468 int ret = 0; 469 struct gb_beagleplay *bg; 470 471 bg = devm_kmalloc(&serdev->dev, sizeof(*bg), GFP_KERNEL); 472 if (!bg) 473 return -ENOMEM; 474 475 bg->sd = serdev; 476 ret = gb_serdev_init(bg); 477 if (ret) 478 return ret; 479 480 ret = hdlc_init(bg); 481 if (ret) 482 goto free_serdev; 483 484 ret = gb_greybus_init(bg); 485 if (ret) 486 goto free_hdlc; 487 488 gb_beagleplay_start_svc(bg); 489 490 return 0; 491 492 free_hdlc: 493 hdlc_deinit(bg); 494 free_serdev: 495 gb_serdev_deinit(bg); 496 return ret; 497 } 498 499 static void gb_beagleplay_remove(struct serdev_device *serdev) 500 { 501 struct gb_beagleplay *bg = serdev_device_get_drvdata(serdev); 502 503 gb_greybus_deinit(bg); 504 gb_beagleplay_stop_svc(bg); 505 hdlc_deinit(bg); 506 gb_serdev_deinit(bg); 507 } 508 509 static const struct of_device_id gb_beagleplay_of_match[] = { 510 { 511 .compatible = "ti,cc1352p7", 512 }, 513 {}, 514 }; 515 MODULE_DEVICE_TABLE(of, gb_beagleplay_of_match); 516 517 static struct serdev_device_driver gb_beagleplay_driver = { 518 .probe = gb_beagleplay_probe, 519 .remove = gb_beagleplay_remove, 520 .driver = { 521 .name = "gb_beagleplay", 522 .of_match_table = gb_beagleplay_of_match, 523 }, 524 }; 525 526 module_serdev_device_driver(gb_beagleplay_driver); 527 528 MODULE_LICENSE("GPL"); 529 MODULE_AUTHOR("Ayush Singh <ayushdevel1325@gmail.com>"); 530 MODULE_DESCRIPTION("A Greybus driver for BeaglePlay"); 531