drivers/greybus/gb-beagleplay.c

   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 static void hdlc_rx_greybus_frame(struct gb_beagleplay *bg, u8 *buf, u16 len)
  89 {
  90         u16 cport_id;
  91         struct gb_operation_msg_hdr *hdr = (struct gb_operation_msg_hdr *)buf;
  92
  93         memcpy(&cport_id, hdr->pad, sizeof(cport_id));
  94
  95         dev_dbg(&bg->sd->dev, "Greybus Operation %u type %X cport %u status %u received",
  96                 hdr->operation_id, hdr->type, cport_id, hdr->result);
  97
  98         greybus_data_rcvd(bg->gb_hd, cport_id, buf, len);
  99 }
 100
 101 static void hdlc_rx_dbg_frame(const struct gb_beagleplay *bg, const char *buf, u16 len)
 102 {
 103         dev_dbg(&bg->sd->dev, "CC1352 Log: %.*s", (int)len, buf);
 104 }
 105
 106 /**
 107  * hdlc_write() - Consume HDLC Buffer.
 108  * @bg: beagleplay greybus driver
 109  *
 110  * Assumes that consumer lock has been acquired.
 111  */
 112 static void hdlc_write(struct gb_beagleplay *bg)
 113 {
 114         int written;
 115         /* Start consuming HDLC data */
 116         int head = smp_load_acquire(&bg->tx_circ_buf.head);
 117         int tail = bg->tx_circ_buf.tail;
 118         int count = CIRC_CNT_TO_END(head, tail, TX_CIRC_BUF_SIZE);
 119         const unsigned char *buf = &bg->tx_circ_buf.buf[tail];
 120
 121         if (count > 0) {
 122                 written = serdev_device_write_buf(bg->sd, buf, count);
 123
 124                 /* Finish consuming HDLC data */
 125                 smp_store_release(&bg->tx_circ_buf.tail, (tail + written) & (TX_CIRC_BUF_SIZE - 1));
 126         }
 127 }
 128
 129 /**
 130  * hdlc_append() - Queue HDLC data for sending.
 131  * @bg: beagleplay greybus driver
 132  * @value: hdlc byte to transmit
 133  *
 134  * Assumes that producer lock as been acquired.
 135  */
 136 static void hdlc_append(struct gb_beagleplay *bg, u8 value)
 137 {
 138         int tail, head = bg->tx_circ_buf.head;
 139
 140         while (true) {
 141                 tail = READ_ONCE(bg->tx_circ_buf.tail);
 142
 143                 if (CIRC_SPACE(head, tail, TX_CIRC_BUF_SIZE) >= 1) {
 144                         bg->tx_circ_buf.buf[head] = value;
 145
 146                         /* Finish producing HDLC byte */
 147                         smp_store_release(&bg->tx_circ_buf.head,
 148                                           (head + 1) & (TX_CIRC_BUF_SIZE - 1));
 149                         return;
 150                 }
 151                 dev_warn(&bg->sd->dev, "Tx circ buf full");
 152                 usleep_range(3000, 5000);
 153         }
 154 }
 155
 156 static void hdlc_append_escaped(struct gb_beagleplay *bg, u8 value)
 157 {
 158         if (value == HDLC_FRAME || value == HDLC_ESC) {
 159                 hdlc_append(bg, HDLC_ESC);
 160                 value ^= HDLC_XOR;
 161         }
 162         hdlc_append(bg, value);
 163 }
 164
 165 static void hdlc_append_tx_frame(struct gb_beagleplay *bg)
 166 {
 167         bg->tx_crc = 0xFFFF;
 168         hdlc_append(bg, HDLC_FRAME);
 169 }
 170
 171 static void hdlc_append_tx_u8(struct gb_beagleplay *bg, u8 value)
 172 {
 173         bg->tx_crc = crc_ccitt(bg->tx_crc, &value, 1);
 174         hdlc_append_escaped(bg, value);
 175 }
 176
 177 static void hdlc_append_tx_buf(struct gb_beagleplay *bg, const u8 *buf, u16 len)
 178 {
 179         size_t i;
 180
 181         for (i = 0; i < len; i++)
 182                 hdlc_append_tx_u8(bg, buf[i]);
 183 }
 184
 185 static void hdlc_append_tx_crc(struct gb_beagleplay *bg)
 186 {
 187         bg->tx_crc ^= 0xffff;
 188         hdlc_append_escaped(bg, bg->tx_crc & 0xff);
 189         hdlc_append_escaped(bg, (bg->tx_crc >> 8) & 0xff);
 190 }
 191
 192 static void hdlc_transmit(struct work_struct *work)
 193 {
 194         struct gb_beagleplay *bg = container_of(work, struct gb_beagleplay, tx_work);
 195
 196         spin_lock_bh(&bg->tx_consumer_lock);
 197         hdlc_write(bg);
 198         spin_unlock_bh(&bg->tx_consumer_lock);
 199 }
 200
 201 static void hdlc_tx_frames(struct gb_beagleplay *bg, u8 address, u8 control,
 202                            const struct hdlc_payload payloads[], size_t count)
 203 {
 204         size_t i;
 205
 206         spin_lock(&bg->tx_producer_lock);
 207
 208         hdlc_append_tx_frame(bg);
 209         hdlc_append_tx_u8(bg, address);
 210         hdlc_append_tx_u8(bg, control);
 211
 212         for (i = 0; i < count; ++i)
 213                 hdlc_append_tx_buf(bg, payloads[i].buf, payloads[i].len);
 214
 215         hdlc_append_tx_crc(bg);
 216         hdlc_append_tx_frame(bg);
 217
 218         spin_unlock(&bg->tx_producer_lock);
 219
 220         schedule_work(&bg->tx_work);
 221 }
 222
 223 static void hdlc_tx_s_frame_ack(struct gb_beagleplay *bg)
 224 {
 225         hdlc_tx_frames(bg, bg->rx_buffer[0], (bg->rx_buffer[1] >> 1) & 0x7, NULL, 0);
 226 }
 227
 228 static void hdlc_rx_frame(struct gb_beagleplay *bg)
 229 {
 230         u16 crc, len;
 231         u8 ctrl, *buf;
 232         u8 address = bg->rx_buffer[0];
 233
 234         crc = crc_ccitt(0xffff, bg->rx_buffer, bg->rx_buffer_len);
 235         if (crc != 0xf0b8) {
 236                 dev_warn_ratelimited(&bg->sd->dev, "CRC failed from %02x: 0x%04x", address, crc);
 237                 return;
 238         }
 239
 240         ctrl = bg->rx_buffer[1];
 241         buf = &bg->rx_buffer[2];
 242         len = bg->rx_buffer_len - 4;
 243
 244         /* I-Frame, send S-Frame ACK */
 245         if ((ctrl & 1) == 0)
 246                 hdlc_tx_s_frame_ack(bg);
 247
 248         switch (address) {
 249         case ADDRESS_DBG:
 250                 hdlc_rx_dbg_frame(bg, buf, len);
 251                 break;
 252         case ADDRESS_GREYBUS:
 253                 hdlc_rx_greybus_frame(bg, buf, len);
 254                 break;
 255         default:
 256                 dev_warn_ratelimited(&bg->sd->dev, "unknown frame %u", address);
 257         }
 258 }
 259
 260 static int hdlc_rx(struct gb_beagleplay *bg, const u8 *data, size_t count)
 261 {
 262         size_t i;
 263         u8 c;
 264
 265         for (i = 0; i < count; ++i) {
 266                 c = data[i];
 267
 268                 switch (c) {
 269                 case HDLC_FRAME:
 270                         if (bg->rx_buffer_len)
 271                                 hdlc_rx_frame(bg);
 272
 273                         bg->rx_buffer_len = 0;
 274                         break;
 275                 case HDLC_ESC:
 276                         bg->rx_in_esc = true;
 277                         break;
 278                 default:
 279                         if (bg->rx_in_esc) {
 280                                 c ^= 0x20;
 281                                 bg->rx_in_esc = false;
 282                         }
 283
 284                         if (bg->rx_buffer_len < MAX_RX_HDLC) {
 285                                 bg->rx_buffer[bg->rx_buffer_len] = c;
 286                                 bg->rx_buffer_len++;
 287                         } else {
 288                                 dev_err_ratelimited(&bg->sd->dev, "RX Buffer Overflow");
 289                                 bg->rx_buffer_len = 0;
 290                         }
 291                 }
 292         }
 293
 294         return count;
 295 }
 296
 297 static int hdlc_init(struct gb_beagleplay *bg)
 298 {
 299         INIT_WORK(&bg->tx_work, hdlc_transmit);
 300         spin_lock_init(&bg->tx_producer_lock);
 301         spin_lock_init(&bg->tx_consumer_lock);
 302         bg->tx_circ_buf.head = 0;
 303         bg->tx_circ_buf.tail = 0;
 304
 305         bg->tx_circ_buf.buf = devm_kmalloc(&bg->sd->dev, TX_CIRC_BUF_SIZE, GFP_KERNEL);
 306         if (!bg->tx_circ_buf.buf)
 307                 return -ENOMEM;
 308
 309         bg->rx_buffer_len = 0;
 310         bg->rx_in_esc = false;
 311
 312         return 0;
 313 }
 314
 315 static void hdlc_deinit(struct gb_beagleplay *bg)
 316 {
 317         flush_work(&bg->tx_work);
 318 }
 319
 320 static int gb_tty_receive(struct serdev_device *sd, const unsigned char *data, size_t count)
 321 {
 322         struct gb_beagleplay *bg = serdev_device_get_drvdata(sd);
 323
 324         return hdlc_rx(bg, data, count);
 325 }
 326
 327 static void gb_tty_wakeup(struct serdev_device *serdev)
 328 {
 329         struct gb_beagleplay *bg = serdev_device_get_drvdata(serdev);
 330
 331         schedule_work(&bg->tx_work);
 332 }
 333
 334 static struct serdev_device_ops gb_beagleplay_ops = {
 335         .receive_buf = gb_tty_receive,
 336         .write_wakeup = gb_tty_wakeup,
 337 };
 338
 339 static int gb_message_send(struct gb_host_device *hd, u16 cport, struct gb_message *msg, gfp_t mask)
 340 {
 341         struct gb_beagleplay *bg = dev_get_drvdata(&hd->dev);
 342         struct hdlc_payload payloads[2];
 343
 344         dev_dbg(&hd->dev, "Sending greybus message with Operation %u, Type: %X on Cport %u",
 345                 msg->header->operation_id, msg->header->type, cport);
 346
 347         if (msg->header->size > RX_HDLC_PAYLOAD)
 348                 return dev_err_probe(&hd->dev, -E2BIG, "Greybus message too big");
 349
 350         memcpy(msg->header->pad, &cport, sizeof(cport));
 351
 352         payloads[0].buf = msg->header;
 353         payloads[0].len = sizeof(*msg->header);
 354         payloads[1].buf = msg->payload;
 355         payloads[1].len = msg->payload_size;
 356
 357         hdlc_tx_frames(bg, ADDRESS_GREYBUS, 0x03, payloads, 2);
 358         greybus_message_sent(bg->gb_hd, msg, 0);
 359
 360         return 0;
 361 }
 362
 363 static void gb_message_cancel(struct gb_message *message)
 364 {
 365 }
 366
 367 static struct gb_hd_driver gb_hdlc_driver = { .message_send = gb_message_send,
 368                                               .message_cancel = gb_message_cancel };
 369
 370 static void gb_beagleplay_start_svc(struct gb_beagleplay *bg)
 371 {
 372         const u8 command = CONTROL_SVC_START;
 373         const struct hdlc_payload payload = { .len = 1, .buf = (void *)&command };
 374
 375         hdlc_tx_frames(bg, ADDRESS_CONTROL, 0x03, &payload, 1);
 376 }
 377
 378 static void gb_beagleplay_stop_svc(struct gb_beagleplay *bg)
 379 {
 380         const u8 command = CONTROL_SVC_STOP;
 381         const struct hdlc_payload payload = { .len = 1, .buf = (void *)&command };
 382
 383         hdlc_tx_frames(bg, ADDRESS_CONTROL, 0x03, &payload, 1);
 384 }
 385
 386 static void gb_greybus_deinit(struct gb_beagleplay *bg)
 387 {
 388         gb_hd_del(bg->gb_hd);
 389         gb_hd_put(bg->gb_hd);
 390 }
 391
 392 static int gb_greybus_init(struct gb_beagleplay *bg)
 393 {
 394         int ret;
 395
 396         bg->gb_hd = gb_hd_create(&gb_hdlc_driver, &bg->sd->dev, TX_CIRC_BUF_SIZE, GB_MAX_CPORTS);
 397         if (IS_ERR(bg->gb_hd)) {
 398                 dev_err(&bg->sd->dev, "Failed to create greybus host device");
 399                 return PTR_ERR(bg->gb_hd);
 400         }
 401
 402         ret = gb_hd_add(bg->gb_hd);
 403         if (ret) {
 404                 dev_err(&bg->sd->dev, "Failed to add greybus host device");
 405                 goto free_gb_hd;
 406         }
 407         dev_set_drvdata(&bg->gb_hd->dev, bg);
 408
 409         return 0;
 410
 411 free_gb_hd:
 412         gb_greybus_deinit(bg);
 413         return ret;
 414 }
 415
 416 static void gb_serdev_deinit(struct gb_beagleplay *bg)
 417 {
 418         serdev_device_close(bg->sd);
 419 }
 420
 421 static int gb_serdev_init(struct gb_beagleplay *bg)
 422 {
 423         int ret;
 424
 425         serdev_device_set_drvdata(bg->sd, bg);
 426         serdev_device_set_client_ops(bg->sd, &gb_beagleplay_ops);
 427         ret = serdev_device_open(bg->sd);
 428         if (ret)
 429                 return dev_err_probe(&bg->sd->dev, ret, "Unable to open serial device");
 430
 431         serdev_device_set_baudrate(bg->sd, 115200);
 432         serdev_device_set_flow_control(bg->sd, false);
 433
 434         return 0;
 435 }
 436
 437 static int gb_beagleplay_probe(struct serdev_device *serdev)
 438 {
 439         int ret = 0;
 440         struct gb_beagleplay *bg;
 441
 442         bg = devm_kmalloc(&serdev->dev, sizeof(*bg), GFP_KERNEL);
 443         if (!bg)
 444                 return -ENOMEM;
 445
 446         bg->sd = serdev;
 447         ret = gb_serdev_init(bg);
 448         if (ret)
 449                 return ret;
 450
 451         ret = hdlc_init(bg);
 452         if (ret)
 453                 goto free_serdev;
 454
 455         ret = gb_greybus_init(bg);
 456         if (ret)
 457                 goto free_hdlc;
 458
 459         gb_beagleplay_start_svc(bg);
 460
 461         return 0;
 462
 463 free_hdlc:
 464         hdlc_deinit(bg);
 465 free_serdev:
 466         gb_serdev_deinit(bg);
 467         return ret;
 468 }
 469
 470 static void gb_beagleplay_remove(struct serdev_device *serdev)
 471 {
 472         struct gb_beagleplay *bg = serdev_device_get_drvdata(serdev);
 473
 474         gb_greybus_deinit(bg);
 475         gb_beagleplay_stop_svc(bg);
 476         hdlc_deinit(bg);
 477         gb_serdev_deinit(bg);
 478 }
 479
 480 static const struct of_device_id gb_beagleplay_of_match[] = {
 481         {
 482                 .compatible = "ti,cc1352p7",
 483         },
 484         {},
 485 };
 486 MODULE_DEVICE_TABLE(of, gb_beagleplay_of_match);
 487
 488 static struct serdev_device_driver gb_beagleplay_driver = {
 489         .probe = gb_beagleplay_probe,
 490         .remove = gb_beagleplay_remove,
 491         .driver = {
 492                 .name = "gb_beagleplay",
 493                 .of_match_table = gb_beagleplay_of_match,
 494         },
 495 };
 496
 497 module_serdev_device_driver(gb_beagleplay_driver);
 498
 499 MODULE_LICENSE("GPL");
 500 MODULE_AUTHOR("Ayush Singh <ayushdevel1325@gmail.com>");
 501 MODULE_DESCRIPTION("A Greybus driver for BeaglePlay");