drivers/staging/pi433/pi433_if.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * userspace interface for pi433 radio module
   4  *
   5  * Pi433 is a 433MHz radio module for the Raspberry Pi.
   6  * It is based on the HopeRf Module RFM69CW. Therefore inside of this
   7  * driver, you'll find an abstraction of the rf69 chip.
   8  *
   9  * If needed, this driver could be extended, to also support other
  10  * devices, basing on HopeRfs rf69.
  11  *
  12  * The driver can also be extended, to support other modules of
  13  * HopeRf with a similar interace - e. g. RFM69HCW, RFM12, RFM95, ...
  14  *
  15  * Copyright (C) 2016 Wolf-Entwicklungen
  16  *      Marcus Wolf <[email protected]>
  17  */
  18
  19 #undef DEBUG
  20
  21 #include <linux/init.h>
  22 #include <linux/module.h>
  23 #include <linux/idr.h>
  24 #include <linux/ioctl.h>
  25 #include <linux/uaccess.h>
  26 #include <linux/fs.h>
  27 #include <linux/device.h>
  28 #include <linux/cdev.h>
  29 #include <linux/err.h>
  30 #include <linux/kfifo.h>
  31 #include <linux/errno.h>
  32 #include <linux/mutex.h>
  33 #include <linux/of.h>
  34 #include <linux/of_device.h>
  35 #include <linux/interrupt.h>
  36 #include <linux/irq.h>
  37 #include <linux/gpio/consumer.h>
  38 #include <linux/kthread.h>
  39 #include <linux/wait.h>
  40 #include <linux/spi/spi.h>
  41 #ifdef CONFIG_COMPAT
  42 #include <linux/compat.h>
  43 #endif
  44
  45 #include "pi433_if.h"
  46 #include "rf69.h"
  47
  48 #define N_PI433_MINORS          BIT(MINORBITS) /*32*/   /* ... up to 256 */
  49 #define MAX_MSG_SIZE            900     /* min: FIFO_SIZE! */
  50 #define MSG_FIFO_SIZE           65536   /* 65536 = 2^16  */
  51 #define NUM_DIO                 2
  52
  53 static dev_t pi433_dev;
  54 static DEFINE_IDR(pi433_idr);
  55 static DEFINE_MUTEX(minor_lock); /* Protect idr accesses */
  56
  57 static struct class *pi433_class; /* mainly for udev to create /dev/pi433 */
  58
  59 /*
  60  * tx config is instance specific
  61  * so with each open a new tx config struct is needed
  62  */
  63 /*
  64  * rx config is device specific
  65  * so we have just one rx config, ebedded in device struct
  66  */
  67 struct pi433_device {
  68         /* device handling related values */
  69         dev_t                   devt;
  70         int                     minor;
  71         struct device           *dev;
  72         struct cdev             *cdev;
  73         struct spi_device       *spi;
  74
  75         /* irq related values */
  76         struct gpio_desc        *gpiod[NUM_DIO];
  77         int                     irq_num[NUM_DIO];
  78         u8                      irq_state[NUM_DIO];
  79
  80         /* tx related values */
  81         STRUCT_KFIFO_REC_1(MSG_FIFO_SIZE) tx_fifo;
  82         struct mutex            tx_fifo_lock; /* serialize userspace writers */
  83         struct task_struct      *tx_task_struct;
  84         wait_queue_head_t       tx_wait_queue;
  85         u8                      free_in_fifo;
  86         char                    buffer[MAX_MSG_SIZE];
  87
  88         /* rx related values */
  89         struct pi433_rx_cfg     rx_cfg;
  90         u8                      *rx_buffer;
  91         unsigned int            rx_buffer_size;
  92         u32                     rx_bytes_to_drop;
  93         u32                     rx_bytes_dropped;
  94         unsigned int            rx_position;
  95         struct mutex            rx_lock; /* protects rx_* variable accesses */
  96         wait_queue_head_t       rx_wait_queue;
  97
  98         /* fifo wait queue */
  99         struct task_struct      *fifo_task_struct;
 100         wait_queue_head_t       fifo_wait_queue;
 101
 102         /* flags */
 103         bool                    rx_active;
 104         bool                    tx_active;
 105         bool                    interrupt_rx_allowed;
 106 };
 107
 108 struct pi433_instance {
 109         struct pi433_device     *device;
 110         struct pi433_tx_cfg     tx_cfg;
 111 };
 112
 113 /*-------------------------------------------------------------------------*/
 114
 115 /* GPIO interrupt handlers */
 116 static irqreturn_t DIO0_irq_handler(int irq, void *dev_id)
 117 {
 118         struct pi433_device *device = dev_id;
 119
 120         if (device->irq_state[DIO0] == DIO_PACKET_SENT) {
 121                 device->free_in_fifo = FIFO_SIZE;
 122                 dev_dbg(device->dev, "DIO0 irq: Packet sent\n");
 123                 wake_up_interruptible(&device->fifo_wait_queue);
 124         } else if (device->irq_state[DIO0] == DIO_RSSI_DIO0) {
 125                 dev_dbg(device->dev, "DIO0 irq: RSSI level over threshold\n");
 126                 wake_up_interruptible(&device->rx_wait_queue);
 127         } else if (device->irq_state[DIO0] == DIO_PAYLOAD_READY) {
 128                 dev_dbg(device->dev, "DIO0 irq: Payload ready\n");
 129                 device->free_in_fifo = 0;
 130                 wake_up_interruptible(&device->fifo_wait_queue);
 131         }
 132
 133         return IRQ_HANDLED;
 134 }
 135
 136 static irqreturn_t DIO1_irq_handler(int irq, void *dev_id)
 137 {
 138         struct pi433_device *device = dev_id;
 139
 140         if (device->irq_state[DIO1] == DIO_FIFO_NOT_EMPTY_DIO1) {
 141                 device->free_in_fifo = FIFO_SIZE;
 142         } else if (device->irq_state[DIO1] == DIO_FIFO_LEVEL) {
 143                 if (device->rx_active)
 144                         device->free_in_fifo = FIFO_THRESHOLD - 1;
 145                 else
 146                         device->free_in_fifo = FIFO_SIZE - FIFO_THRESHOLD - 1;
 147         }
 148         dev_dbg(device->dev,
 149                 "DIO1 irq: %d bytes free in fifo\n", device->free_in_fifo);
 150         wake_up_interruptible(&device->fifo_wait_queue);
 151
 152         return IRQ_HANDLED;
 153 }
 154
 155 /*-------------------------------------------------------------------------*/
 156
 157 static int
 158 rf69_set_rx_cfg(struct pi433_device *dev, struct pi433_rx_cfg *rx_cfg)
 159 {
 160         int ret;
 161         int payload_length;
 162
 163         /* receiver config */
 164         ret = rf69_set_frequency(dev->spi, rx_cfg->frequency);
 165         if (ret < 0)
 166                 return ret;
 167         ret = rf69_set_bit_rate(dev->spi, rx_cfg->bit_rate);
 168         if (ret < 0)
 169                 return ret;
 170         ret = rf69_set_modulation(dev->spi, rx_cfg->modulation);
 171         if (ret < 0)
 172                 return ret;
 173         ret = rf69_set_antenna_impedance(dev->spi, rx_cfg->antenna_impedance);
 174         if (ret < 0)
 175                 return ret;
 176         ret = rf69_set_rssi_threshold(dev->spi, rx_cfg->rssi_threshold);
 177         if (ret < 0)
 178                 return ret;
 179         ret = rf69_set_ook_threshold_dec(dev->spi, rx_cfg->threshold_decrement);
 180         if (ret < 0)
 181                 return ret;
 182         ret = rf69_set_bandwidth(dev->spi, rx_cfg->bw_mantisse,
 183                                  rx_cfg->bw_exponent);
 184         if (ret < 0)
 185                 return ret;
 186         ret = rf69_set_bandwidth_during_afc(dev->spi, rx_cfg->bw_mantisse,
 187                                             rx_cfg->bw_exponent);
 188         if (ret < 0)
 189                 return ret;
 190         ret = rf69_set_dagc(dev->spi, rx_cfg->dagc);
 191         if (ret < 0)
 192                 return ret;
 193
 194         dev->rx_bytes_to_drop = rx_cfg->bytes_to_drop;
 195
 196         /* packet config */
 197         /* enable */
 198         if (rx_cfg->enable_sync == OPTION_ON) {
 199                 ret = rf69_enable_sync(dev->spi);
 200                 if (ret < 0)
 201                         return ret;
 202
 203                 ret = rf69_set_fifo_fill_condition(dev->spi,
 204                                                    after_sync_interrupt);
 205                 if (ret < 0)
 206                         return ret;
 207         } else {
 208                 ret = rf69_disable_sync(dev->spi);
 209                 if (ret < 0)
 210                         return ret;
 211
 212                 ret = rf69_set_fifo_fill_condition(dev->spi, always);
 213                 if (ret < 0)
 214                         return ret;
 215         }
 216         if (rx_cfg->enable_length_byte == OPTION_ON) {
 217                 ret = rf69_set_packet_format(dev->spi, packet_length_var);
 218                 if (ret < 0)
 219                         return ret;
 220         } else {
 221                 ret = rf69_set_packet_format(dev->spi, packet_length_fix);
 222                 if (ret < 0)
 223                         return ret;
 224         }
 225         ret = rf69_set_address_filtering(dev->spi,
 226                                          rx_cfg->enable_address_filtering);
 227         if (ret < 0)
 228                 return ret;
 229
 230         if (rx_cfg->enable_crc == OPTION_ON) {
 231                 ret = rf69_enable_crc(dev->spi);
 232                 if (ret < 0)
 233                         return ret;
 234         } else {
 235                 ret = rf69_disable_crc(dev->spi);
 236                 if (ret < 0)
 237                         return ret;
 238         }
 239
 240         /* lengths */
 241         ret = rf69_set_sync_size(dev->spi, rx_cfg->sync_length);
 242         if (ret < 0)
 243                 return ret;
 244         if (rx_cfg->enable_length_byte == OPTION_ON) {
 245                 ret = rf69_set_payload_length(dev->spi, 0xff);
 246                 if (ret < 0)
 247                         return ret;
 248         } else if (rx_cfg->fixed_message_length != 0) {
 249                 payload_length = rx_cfg->fixed_message_length;
 250                 if (rx_cfg->enable_length_byte  == OPTION_ON)
 251                         payload_length++;
 252                 if (rx_cfg->enable_address_filtering != filtering_off)
 253                         payload_length++;
 254                 ret = rf69_set_payload_length(dev->spi, payload_length);
 255                 if (ret < 0)
 256                         return ret;
 257         } else {
 258                 ret = rf69_set_payload_length(dev->spi, 0);
 259                 if (ret < 0)
 260                         return ret;
 261         }
 262
 263         /* values */
 264         if (rx_cfg->enable_sync == OPTION_ON) {
 265                 ret = rf69_set_sync_values(dev->spi, rx_cfg->sync_pattern);
 266                 if (ret < 0)
 267                         return ret;
 268         }
 269         if (rx_cfg->enable_address_filtering != filtering_off) {
 270                 ret = rf69_set_node_address(dev->spi, rx_cfg->node_address);
 271                 if (ret < 0)
 272                         return ret;
 273                 ret = rf69_set_broadcast_address(dev->spi,
 274                                                  rx_cfg->broadcast_address);
 275                 if (ret < 0)
 276                         return ret;
 277         }
 278
 279         return 0;
 280 }
 281
 282 static int
 283 rf69_set_tx_cfg(struct pi433_device *dev, struct pi433_tx_cfg *tx_cfg)
 284 {
 285         int ret;
 286
 287         ret = rf69_set_frequency(dev->spi, tx_cfg->frequency);
 288         if (ret < 0)
 289                 return ret;
 290         ret = rf69_set_bit_rate(dev->spi, tx_cfg->bit_rate);
 291         if (ret < 0)
 292                 return ret;
 293         ret = rf69_set_modulation(dev->spi, tx_cfg->modulation);
 294         if (ret < 0)
 295                 return ret;
 296         ret = rf69_set_deviation(dev->spi, tx_cfg->dev_frequency);
 297         if (ret < 0)
 298                 return ret;
 299         ret = rf69_set_pa_ramp(dev->spi, tx_cfg->pa_ramp);
 300         if (ret < 0)
 301                 return ret;
 302         ret = rf69_set_modulation_shaping(dev->spi, tx_cfg->mod_shaping);
 303         if (ret < 0)
 304                 return ret;
 305         ret = rf69_set_tx_start_condition(dev->spi, tx_cfg->tx_start_condition);
 306         if (ret < 0)
 307                 return ret;
 308
 309         /* packet format enable */
 310         if (tx_cfg->enable_preamble == OPTION_ON) {
 311                 ret = rf69_set_preamble_length(dev->spi,
 312                                                tx_cfg->preamble_length);
 313                 if (ret < 0)
 314                         return ret;
 315         } else {
 316                 ret = rf69_set_preamble_length(dev->spi, 0);
 317                 if (ret < 0)
 318                         return ret;
 319         }
 320
 321         if (tx_cfg->enable_sync == OPTION_ON) {
 322                 ret = rf69_set_sync_size(dev->spi, tx_cfg->sync_length);
 323                 if (ret < 0)
 324                         return ret;
 325                 ret = rf69_set_sync_values(dev->spi, tx_cfg->sync_pattern);
 326                 if (ret < 0)
 327                         return ret;
 328                 ret = rf69_enable_sync(dev->spi);
 329                 if (ret < 0)
 330                         return ret;
 331         } else {
 332                 ret = rf69_disable_sync(dev->spi);
 333                 if (ret < 0)
 334                         return ret;
 335         }
 336
 337         if (tx_cfg->enable_length_byte == OPTION_ON) {
 338                 ret = rf69_set_packet_format(dev->spi, packet_length_var);
 339                 if (ret < 0)
 340                         return ret;
 341         } else {
 342                 ret = rf69_set_packet_format(dev->spi, packet_length_fix);
 343                 if (ret < 0)
 344                         return ret;
 345         }
 346
 347         if (tx_cfg->enable_crc == OPTION_ON) {
 348                 ret = rf69_enable_crc(dev->spi);
 349                 if (ret < 0)
 350                         return ret;
 351         } else {
 352                 ret = rf69_disable_crc(dev->spi);
 353                 if (ret < 0)
 354                         return ret;
 355         }
 356
 357         return 0;
 358 }
 359
 360 /*-------------------------------------------------------------------------*/
 361
 362 static int
 363 pi433_start_rx(struct pi433_device *dev)
 364 {
 365         int retval;
 366
 367         /* return without action, if no pending read request */
 368         if (!dev->rx_active)
 369                 return 0;
 370
 371         /* setup for receiving */
 372         retval = rf69_set_rx_cfg(dev, &dev->rx_cfg);
 373         if (retval)
 374                 return retval;
 375
 376         /* setup rssi irq */
 377         retval = rf69_set_dio_mapping(dev->spi, DIO0, DIO_RSSI_DIO0);
 378         if (retval < 0)
 379                 return retval;
 380         dev->irq_state[DIO0] = DIO_RSSI_DIO0;
 381         irq_set_irq_type(dev->irq_num[DIO0], IRQ_TYPE_EDGE_RISING);
 382
 383         /* setup fifo level interrupt */
 384         retval = rf69_set_fifo_threshold(dev->spi, FIFO_SIZE - FIFO_THRESHOLD);
 385         if (retval < 0)
 386                 return retval;
 387         retval = rf69_set_dio_mapping(dev->spi, DIO1, DIO_FIFO_LEVEL);
 388         if (retval < 0)
 389                 return retval;
 390         dev->irq_state[DIO1] = DIO_FIFO_LEVEL;
 391         irq_set_irq_type(dev->irq_num[DIO1], IRQ_TYPE_EDGE_RISING);
 392
 393         /* set module to receiving mode */
 394         retval = rf69_set_mode(dev->spi, receive);
 395         if (retval < 0)
 396                 return retval;
 397
 398         return 0;
 399 }
 400
 401 /*-------------------------------------------------------------------------*/
 402
 403 static int
 404 pi433_receive(void *data)
 405 {
 406         struct pi433_device *dev = data;
 407         struct spi_device *spi = dev->spi;
 408         int bytes_to_read, bytes_total;
 409         int retval;
 410
 411         dev->interrupt_rx_allowed = false;
 412
 413         /* wait for any tx to finish */
 414         dev_dbg(dev->dev, "rx: going to wait for any tx to finish");
 415         retval = wait_event_interruptible(dev->rx_wait_queue, !dev->tx_active);
 416         if (retval) {
 417                 /* wait was interrupted */
 418                 dev->interrupt_rx_allowed = true;
 419                 wake_up_interruptible(&dev->tx_wait_queue);
 420                 return retval;
 421         }
 422
 423         /* prepare status vars */
 424         dev->free_in_fifo = FIFO_SIZE;
 425         dev->rx_position = 0;
 426         dev->rx_bytes_dropped = 0;
 427
 428         /* setup radio module to listen for something "in the air" */
 429         retval = pi433_start_rx(dev);
 430         if (retval)
 431                 return retval;
 432
 433         /* now check RSSI, if low wait for getting high (RSSI interrupt) */
 434         while (!rf69_get_flag(dev->spi, rssi_exceeded_threshold)) {
 435                 /* allow tx to interrupt us while waiting for high RSSI */
 436                 dev->interrupt_rx_allowed = true;
 437                 wake_up_interruptible(&dev->tx_wait_queue);
 438
 439                 /* wait for RSSI level to become high */
 440                 dev_dbg(dev->dev, "rx: going to wait for high RSSI level");
 441                 retval = wait_event_interruptible(dev->rx_wait_queue,
 442                                                   rf69_get_flag(dev->spi,
 443                                                                 rssi_exceeded_threshold));
 444                 if (retval) /* wait was interrupted */
 445                         goto abort;
 446                 dev->interrupt_rx_allowed = false;
 447
 448                 /* cross check for ongoing tx */
 449                 if (!dev->tx_active)
 450                         break;
 451         }
 452
 453         /* configure payload ready irq */
 454         retval = rf69_set_dio_mapping(spi, DIO0, DIO_PAYLOAD_READY);
 455         if (retval < 0)
 456                 goto abort;
 457         dev->irq_state[DIO0] = DIO_PAYLOAD_READY;
 458         irq_set_irq_type(dev->irq_num[DIO0], IRQ_TYPE_EDGE_RISING);
 459
 460         /* fixed or unlimited length? */
 461         if (dev->rx_cfg.fixed_message_length != 0) {
 462                 if (dev->rx_cfg.fixed_message_length > dev->rx_buffer_size) {
 463                         retval = -1;
 464                         goto abort;
 465                 }
 466                 bytes_total = dev->rx_cfg.fixed_message_length;
 467                 dev_dbg(dev->dev, "rx: msg len set to %d by fixed length",
 468                         bytes_total);
 469         } else {
 470                 bytes_total = dev->rx_buffer_size;
 471                 dev_dbg(dev->dev, "rx: msg len set to %d as requested by read",
 472                         bytes_total);
 473         }
 474
 475         /* length byte enabled? */
 476         if (dev->rx_cfg.enable_length_byte == OPTION_ON) {
 477                 retval = wait_event_interruptible(dev->fifo_wait_queue,
 478                                                   dev->free_in_fifo < FIFO_SIZE);
 479                 if (retval) /* wait was interrupted */
 480                         goto abort;
 481
 482                 rf69_read_fifo(spi, (u8 *)&bytes_total, 1);
 483                 if (bytes_total > dev->rx_buffer_size) {
 484                         retval = -1;
 485                         goto abort;
 486                 }
 487                 dev->free_in_fifo++;
 488                 dev_dbg(dev->dev, "rx: msg len reset to %d due to length byte",
 489                         bytes_total);
 490         }
 491
 492         /* address byte enabled? */
 493         if (dev->rx_cfg.enable_address_filtering != filtering_off) {
 494                 u8 dummy;
 495
 496                 bytes_total--;
 497
 498                 retval = wait_event_interruptible(dev->fifo_wait_queue,
 499                                                   dev->free_in_fifo < FIFO_SIZE);
 500                 if (retval) /* wait was interrupted */
 501                         goto abort;
 502
 503                 rf69_read_fifo(spi, &dummy, 1);
 504                 dev->free_in_fifo++;
 505                 dev_dbg(dev->dev, "rx: address byte stripped off");
 506         }
 507
 508         /* get payload */
 509         while (dev->rx_position < bytes_total) {
 510                 if (!rf69_get_flag(dev->spi, payload_ready)) {
 511                         retval = wait_event_interruptible(dev->fifo_wait_queue,
 512                                                           dev->free_in_fifo < FIFO_SIZE);
 513                         if (retval) /* wait was interrupted */
 514                                 goto abort;
 515                 }
 516
 517                 /* need to drop bytes or acquire? */
 518                 if (dev->rx_bytes_to_drop > dev->rx_bytes_dropped)
 519                         bytes_to_read = dev->rx_bytes_to_drop -
 520                                         dev->rx_bytes_dropped;
 521                 else
 522                         bytes_to_read = bytes_total - dev->rx_position;
 523
 524                 /* access the fifo */
 525                 if (bytes_to_read > FIFO_SIZE - dev->free_in_fifo)
 526                         bytes_to_read = FIFO_SIZE - dev->free_in_fifo;
 527                 retval = rf69_read_fifo(spi,
 528                                         &dev->rx_buffer[dev->rx_position],
 529                                         bytes_to_read);
 530                 if (retval) /* read failed */
 531                         goto abort;
 532
 533                 dev->free_in_fifo += bytes_to_read;
 534
 535                 /* adjust status vars */
 536                 if (dev->rx_bytes_to_drop > dev->rx_bytes_dropped)
 537                         dev->rx_bytes_dropped += bytes_to_read;
 538                 else
 539                         dev->rx_position += bytes_to_read;
 540         }
 541
 542         /* rx done, wait was interrupted or error occurred */
 543 abort:
 544         dev->interrupt_rx_allowed = true;
 545         if (rf69_set_mode(dev->spi, standby))
 546                 pr_err("rf69_set_mode(): radio module failed to go standby\n");
 547         wake_up_interruptible(&dev->tx_wait_queue);
 548
 549         if (retval)
 550                 return retval;
 551         else
 552                 return bytes_total;
 553 }
 554
 555 static int
 556 pi433_tx_thread(void *data)
 557 {
 558         struct pi433_device *device = data;
 559         struct spi_device *spi = device->spi;
 560         struct pi433_tx_cfg tx_cfg;
 561         size_t size;
 562         bool   rx_interrupted = false;
 563         int    position, repetitions;
 564         int    retval;
 565
 566         while (1) {
 567                 /* wait for fifo to be populated or for request to terminate*/
 568                 dev_dbg(device->dev, "thread: going to wait for new messages");
 569                 wait_event_interruptible(device->tx_wait_queue,
 570                                          (!kfifo_is_empty(&device->tx_fifo) ||
 571                                           kthread_should_stop()));
 572                 if (kthread_should_stop())
 573                         return 0;
 574
 575                 /*
 576                  * get data from fifo in the following order:
 577                  * - tx_cfg
 578                  * - size of message
 579                  * - message
 580                  */
 581                 retval = kfifo_out(&device->tx_fifo, &tx_cfg, sizeof(tx_cfg));
 582                 if (retval != sizeof(tx_cfg)) {
 583                         dev_dbg(device->dev,
 584                                 "reading tx_cfg from fifo failed: got %d byte(s), expected %d",
 585                                 retval, (unsigned int)sizeof(tx_cfg));
 586                         continue;
 587                 }
 588
 589                 retval = kfifo_out(&device->tx_fifo, &size, sizeof(size_t));
 590                 if (retval != sizeof(size_t)) {
 591                         dev_dbg(device->dev,
 592                                 "reading msg size from fifo failed: got %d, expected %d",
 593                                 retval, (unsigned int)sizeof(size_t));
 594                         continue;
 595                 }
 596
 597                 /* use fixed message length, if requested */
 598                 if (tx_cfg.fixed_message_length != 0)
 599                         size = tx_cfg.fixed_message_length;
 600
 601                 /* increase size, if len byte is requested */
 602                 if (tx_cfg.enable_length_byte == OPTION_ON)
 603                         size++;
 604
 605                 /* increase size, if adr byte is requested */
 606                 if (tx_cfg.enable_address_byte == OPTION_ON)
 607                         size++;
 608
 609                 /* prime buffer */
 610                 memset(device->buffer, 0, size);
 611                 position = 0;
 612
 613                 /* add length byte, if requested */
 614                 if (tx_cfg.enable_length_byte  == OPTION_ON)
 615                         /*
 616                          * according to spec, length byte itself must be
 617                          * excluded from the length calculation
 618                          */
 619                         device->buffer[position++] = size - 1;
 620
 621                 /* add adr byte, if requested */
 622                 if (tx_cfg.enable_address_byte == OPTION_ON)
 623                         device->buffer[position++] = tx_cfg.address_byte;
 624
 625                 /* finally get message data from fifo */
 626                 retval = kfifo_out(&device->tx_fifo, &device->buffer[position],
 627                                    sizeof(device->buffer) - position);
 628                 dev_dbg(device->dev,
 629                         "read %d message byte(s) from fifo queue.", retval);
 630
 631                 /*
 632                  * if rx is active, we need to interrupt the waiting for
 633                  * incoming telegrams, to be able to send something.
 634                  * We are only allowed, if currently no reception takes
 635                  * place otherwise we need to  wait for the incoming telegram
 636                  * to finish
 637                  */
 638                 wait_event_interruptible(device->tx_wait_queue,
 639                                          !device->rx_active ||
 640                                           device->interrupt_rx_allowed);
 641
 642                 /*
 643                  * prevent race conditions
 644                  * irq will be reenabled after tx config is set
 645                  */
 646                 disable_irq(device->irq_num[DIO0]);
 647                 device->tx_active = true;
 648
 649                 /* clear fifo, set fifo threshold, set payload length */
 650                 retval = rf69_set_mode(spi, standby); /* this clears the fifo */
 651                 if (retval < 0)
 652                         goto abort;
 653
 654                 if (device->rx_active && !rx_interrupted) {
 655                         /*
 656                          * rx is currently waiting for a telegram;
 657                          * we need to set the radio module to standby
 658                          */
 659                         rx_interrupted = true;
 660                 }
 661
 662                 retval = rf69_set_fifo_threshold(spi, FIFO_THRESHOLD);
 663                 if (retval < 0)
 664                         goto abort;
 665                 if (tx_cfg.enable_length_byte == OPTION_ON) {
 666                         retval = rf69_set_payload_length(spi, size * tx_cfg.repetitions);
 667                         if (retval < 0)
 668                                 goto abort;
 669                 } else {
 670                         retval = rf69_set_payload_length(spi, 0);
 671                         if (retval < 0)
 672                                 goto abort;
 673                 }
 674
 675                 /* configure the rf chip */
 676                 retval = rf69_set_tx_cfg(device, &tx_cfg);
 677                 if (retval < 0)
 678                         goto abort;
 679
 680                 /* enable fifo level interrupt */
 681                 retval = rf69_set_dio_mapping(spi, DIO1, DIO_FIFO_LEVEL);
 682                 if (retval < 0)
 683                         goto abort;
 684                 device->irq_state[DIO1] = DIO_FIFO_LEVEL;
 685                 irq_set_irq_type(device->irq_num[DIO1], IRQ_TYPE_EDGE_FALLING);
 686
 687                 /* enable packet sent interrupt */
 688                 retval = rf69_set_dio_mapping(spi, DIO0, DIO_PACKET_SENT);
 689                 if (retval < 0)
 690                         goto abort;
 691                 device->irq_state[DIO0] = DIO_PACKET_SENT;
 692                 irq_set_irq_type(device->irq_num[DIO0], IRQ_TYPE_EDGE_RISING);
 693                 enable_irq(device->irq_num[DIO0]); /* was disabled by rx active check */
 694
 695                 /* enable transmission */
 696                 retval = rf69_set_mode(spi, transmit);
 697                 if (retval < 0)
 698                         goto abort;
 699
 700                 /* transfer this msg (and repetitions) to chip fifo */
 701                 device->free_in_fifo = FIFO_SIZE;
 702                 position = 0;
 703                 repetitions = tx_cfg.repetitions;
 704                 while ((repetitions > 0) && (size > position)) {
 705                         if ((size - position) > device->free_in_fifo) {
 706                                 /* msg to big for fifo - take a part */
 707                                 int write_size = device->free_in_fifo;
 708
 709                                 device->free_in_fifo = 0;
 710                                 rf69_write_fifo(spi,
 711                                                 &device->buffer[position],
 712                                                 write_size);
 713                                 position += write_size;
 714                         } else {
 715                                 /* msg fits into fifo - take all */
 716                                 device->free_in_fifo -= size;
 717                                 repetitions--;
 718                                 rf69_write_fifo(spi,
 719                                                 &device->buffer[position],
 720                                                 (size - position));
 721                                 position = 0; /* reset for next repetition */
 722                         }
 723
 724                         retval = wait_event_interruptible(device->fifo_wait_queue,
 725                                                           device->free_in_fifo > 0);
 726                         if (retval) {
 727                                 dev_dbg(device->dev, "ABORT\n");
 728                                 goto abort;
 729                         }
 730                 }
 731
 732                 /* we are done. Wait for packet to get sent */
 733                 dev_dbg(device->dev,
 734                         "thread: wait for packet to get sent/fifo to be empty");
 735                 wait_event_interruptible(device->fifo_wait_queue,
 736                                          device->free_in_fifo == FIFO_SIZE ||
 737                                          kthread_should_stop());
 738                 if (kthread_should_stop())
 739                         return 0;
 740
 741                 /* STOP_TRANSMISSION */
 742                 dev_dbg(device->dev, "thread: Packet sent. Set mode to stby.");
 743                 retval = rf69_set_mode(spi, standby);
 744                 if (retval < 0)
 745                         goto abort;
 746
 747                 /* everything sent? */
 748                 if (kfifo_is_empty(&device->tx_fifo)) {
 749 abort:
 750                         if (rx_interrupted) {
 751                                 rx_interrupted = false;
 752                                 pi433_start_rx(device);
 753                         }
 754                         device->tx_active = false;
 755                         wake_up_interruptible(&device->rx_wait_queue);
 756                 }
 757         }
 758 }
 759
 760 /*-------------------------------------------------------------------------*/
 761
 762 static ssize_t
 763 pi433_read(struct file *filp, char __user *buf, size_t size, loff_t *f_pos)
 764 {
 765         struct pi433_instance   *instance;
 766         struct pi433_device     *device;
 767         int                     bytes_received;
 768         ssize_t                 retval;
 769
 770         /* check, whether internal buffer is big enough for requested size */
 771         if (size > MAX_MSG_SIZE)
 772                 return -EMSGSIZE;
 773
 774         instance = filp->private_data;
 775         device = instance->device;
 776
 777         /* just one read request at a time */
 778         mutex_lock(&device->rx_lock);
 779         if (device->rx_active) {
 780                 mutex_unlock(&device->rx_lock);
 781                 return -EAGAIN;
 782         }
 783
 784         device->rx_active = true;
 785         mutex_unlock(&device->rx_lock);
 786
 787         /* start receiving */
 788         /* will block until something was received*/
 789         device->rx_buffer_size = size;
 790         bytes_received = pi433_receive(device);
 791
 792         /* release rx */
 793         mutex_lock(&device->rx_lock);
 794         device->rx_active = false;
 795         mutex_unlock(&device->rx_lock);
 796
 797         /* if read was successful copy to user space*/
 798         if (bytes_received > 0) {
 799                 retval = copy_to_user(buf, device->rx_buffer, bytes_received);
 800                 if (retval)
 801                         return -EFAULT;
 802         }
 803
 804         return bytes_received;
 805 }
 806
 807 static ssize_t
 808 pi433_write(struct file *filp, const char __user *buf,
 809             size_t count, loff_t *f_pos)
 810 {
 811         struct pi433_instance   *instance;
 812         struct pi433_device     *device;
 813         int                     retval;
 814         unsigned int            required, available, copied;
 815
 816         instance = filp->private_data;
 817         device = instance->device;
 818
 819         /*
 820          * check, whether internal buffer (tx thread) is big enough
 821          * for requested size
 822          */
 823         if (count > MAX_MSG_SIZE)
 824                 return -EMSGSIZE;
 825
 826         /*
 827          * write the following sequence into fifo:
 828          * - tx_cfg
 829          * - size of message
 830          * - message
 831          */
 832         mutex_lock(&device->tx_fifo_lock);
 833
 834         required = sizeof(instance->tx_cfg) + sizeof(size_t) + count;
 835         available = kfifo_avail(&device->tx_fifo);
 836         if (required > available) {
 837                 dev_dbg(device->dev, "write to fifo failed: %d bytes required but %d available",
 838                         required, available);
 839                 mutex_unlock(&device->tx_fifo_lock);
 840                 return -EAGAIN;
 841         }
 842
 843         retval = kfifo_in(&device->tx_fifo, &instance->tx_cfg,
 844                           sizeof(instance->tx_cfg));
 845         if (retval != sizeof(instance->tx_cfg))
 846                 goto abort;
 847
 848         retval = kfifo_in(&device->tx_fifo, &count, sizeof(size_t));
 849         if (retval != sizeof(size_t))
 850                 goto abort;
 851
 852         retval = kfifo_from_user(&device->tx_fifo, buf, count, &copied);
 853         if (retval || copied != count)
 854                 goto abort;
 855
 856         mutex_unlock(&device->tx_fifo_lock);
 857
 858         /* start transfer */
 859         wake_up_interruptible(&device->tx_wait_queue);
 860         dev_dbg(device->dev, "write: generated new msg with %d bytes.", copied);
 861
 862         return copied;
 863
 864 abort:
 865         dev_warn(device->dev,
 866                  "write to fifo failed, non recoverable: 0x%x", retval);
 867         mutex_unlock(&device->tx_fifo_lock);
 868         return -EAGAIN;
 869 }
 870
 871 static long
 872 pi433_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 873 {
 874         struct pi433_instance   *instance;
 875         struct pi433_device     *device;
 876         struct pi433_tx_cfg     tx_cfg;
 877         void __user *argp = (void __user *)arg;
 878
 879         /* Check type and command number */
 880         if (_IOC_TYPE(cmd) != PI433_IOC_MAGIC)
 881                 return -ENOTTY;
 882
 883         instance = filp->private_data;
 884         device = instance->device;
 885
 886         if (!device)
 887                 return -ESHUTDOWN;
 888
 889         switch (cmd) {
 890         case PI433_IOC_RD_TX_CFG:
 891                 if (copy_to_user(argp, &instance->tx_cfg,
 892                                  sizeof(struct pi433_tx_cfg)))
 893                         return -EFAULT;
 894                 break;
 895         case PI433_IOC_WR_TX_CFG:
 896                 if (copy_from_user(&tx_cfg, argp, sizeof(struct pi433_tx_cfg)))
 897                         return -EFAULT;
 898                 mutex_lock(&device->tx_fifo_lock);
 899                 memcpy(&instance->tx_cfg, &tx_cfg, sizeof(struct pi433_tx_cfg));
 900                 mutex_unlock(&device->tx_fifo_lock);
 901                 break;
 902         case PI433_IOC_RD_RX_CFG:
 903                 if (copy_to_user(argp, &device->rx_cfg,
 904                                  sizeof(struct pi433_rx_cfg)))
 905                         return -EFAULT;
 906                 break;
 907         case PI433_IOC_WR_RX_CFG:
 908                 mutex_lock(&device->rx_lock);
 909
 910                 /* during pendig read request, change of config not allowed */
 911                 if (device->rx_active) {
 912                         mutex_unlock(&device->rx_lock);
 913                         return -EAGAIN;
 914                 }
 915
 916                 if (copy_from_user(&device->rx_cfg, argp,
 917                                    sizeof(struct pi433_rx_cfg))) {
 918                         mutex_unlock(&device->rx_lock);
 919                         return -EFAULT;
 920                 }
 921
 922                 mutex_unlock(&device->rx_lock);
 923                 break;
 924         default:
 925                 return -EINVAL;
 926         }
 927
 928         return 0;
 929 }
 930
 931 /*-------------------------------------------------------------------------*/
 932
 933 static int pi433_open(struct inode *inode, struct file *filp)
 934 {
 935         struct pi433_device     *device;
 936         struct pi433_instance   *instance;
 937
 938         mutex_lock(&minor_lock);
 939         device = idr_find(&pi433_idr, iminor(inode));
 940         mutex_unlock(&minor_lock);
 941         if (!device) {
 942                 pr_debug("device: minor %d unknown.\n", iminor(inode));
 943                 return -ENODEV;
 944         }
 945
 946         instance = kzalloc(sizeof(*instance), GFP_KERNEL);
 947         if (!instance)
 948                 return -ENOMEM;
 949
 950         /* setup instance data*/
 951         instance->device = device;
 952         instance->tx_cfg.bit_rate = 4711;
 953         // TODO: fill instance->tx_cfg;
 954
 955         /* instance data as context */
 956         filp->private_data = instance;
 957         stream_open(inode, filp);
 958
 959         return 0;
 960 }
 961
 962 static int pi433_release(struct inode *inode, struct file *filp)
 963 {
 964         struct pi433_instance   *instance;
 965
 966         instance = filp->private_data;
 967         kfree(instance);
 968         filp->private_data = NULL;
 969
 970         return 0;
 971 }
 972
 973 /*-------------------------------------------------------------------------*/
 974
 975 static int setup_gpio(struct pi433_device *device)
 976 {
 977         char    name[5];
 978         int     retval;
 979         int     i;
 980         const irq_handler_t DIO_irq_handler[NUM_DIO] = {
 981                 DIO0_irq_handler,
 982                 DIO1_irq_handler
 983         };
 984
 985         for (i = 0; i < NUM_DIO; i++) {
 986                 /* "construct" name and get the gpio descriptor */
 987                 snprintf(name, sizeof(name), "DIO%d", i);
 988                 device->gpiod[i] = gpiod_get(&device->spi->dev, name,
 989                                              0 /*GPIOD_IN*/);
 990
 991                 if (device->gpiod[i] == ERR_PTR(-ENOENT)) {
 992                         dev_dbg(&device->spi->dev,
 993                                 "Could not find entry for %s. Ignoring.", name);
 994                         continue;
 995                 }
 996
 997                 if (device->gpiod[i] == ERR_PTR(-EBUSY))
 998                         dev_dbg(&device->spi->dev, "%s is busy.", name);
 999
1000                 if (IS_ERR(device->gpiod[i])) {
1001                         retval = PTR_ERR(device->gpiod[i]);
1002                         /* release already allocated gpios */
1003                         for (i--; i >= 0; i--) {
1004                                 free_irq(device->irq_num[i], device);
1005                                 gpiod_put(device->gpiod[i]);
1006                         }
1007                         return retval;
1008                 }
1009
1010                 /* configure the pin */
1011                 gpiod_unexport(device->gpiod[i]);
1012                 retval = gpiod_direction_input(device->gpiod[i]);
1013                 if (retval)
1014                         return retval;
1015
1016                 /* configure irq */
1017                 device->irq_num[i] = gpiod_to_irq(device->gpiod[i]);
1018                 if (device->irq_num[i] < 0) {
1019                         device->gpiod[i] = ERR_PTR(-EINVAL);
1020                         return device->irq_num[i];
1021                 }
1022                 retval = request_irq(device->irq_num[i],
1023                                      DIO_irq_handler[i],
1024                                      0, /* flags */
1025                                      name,
1026                                      device);
1027
1028                 if (retval)
1029                         return retval;
1030
1031                 dev_dbg(&device->spi->dev, "%s successfully configured", name);
1032         }
1033
1034         return 0;
1035 }
1036
1037 static void free_gpio(struct pi433_device *device)
1038 {
1039         int i;
1040
1041         for (i = 0; i < NUM_DIO; i++) {
1042                 /* check if gpiod is valid */
1043                 if (IS_ERR(device->gpiod[i]))
1044                         continue;
1045
1046                 free_irq(device->irq_num[i], device);
1047                 gpiod_put(device->gpiod[i]);
1048         }
1049 }
1050
1051 static int pi433_get_minor(struct pi433_device *device)
1052 {
1053         int retval = -ENOMEM;
1054
1055         mutex_lock(&minor_lock);
1056         retval = idr_alloc(&pi433_idr, device, 0, N_PI433_MINORS, GFP_KERNEL);
1057         if (retval >= 0) {
1058                 device->minor = retval;
1059                 retval = 0;
1060         } else if (retval == -ENOSPC) {
1061                 dev_err(&device->spi->dev, "too many pi433 devices\n");
1062                 retval = -EINVAL;
1063         }
1064         mutex_unlock(&minor_lock);
1065         return retval;
1066 }
1067
1068 static void pi433_free_minor(struct pi433_device *dev)
1069 {
1070         mutex_lock(&minor_lock);
1071         idr_remove(&pi433_idr, dev->minor);
1072         mutex_unlock(&minor_lock);
1073 }
1074
1075 /*-------------------------------------------------------------------------*/
1076
1077 static const struct file_operations pi433_fops = {
1078         .owner =        THIS_MODULE,
1079         /*
1080          * REVISIT switch to aio primitives, so that userspace
1081          * gets more complete API coverage.  It'll simplify things
1082          * too, except for the locking.
1083          */
1084         .write =        pi433_write,
1085         .read =         pi433_read,
1086         .unlocked_ioctl = pi433_ioctl,
1087         .compat_ioctl = compat_ptr_ioctl,
1088         .open =         pi433_open,
1089         .release =      pi433_release,
1090         .llseek =       no_llseek,
1091 };
1092
1093 /*-------------------------------------------------------------------------*/
1094
1095 static int pi433_probe(struct spi_device *spi)
1096 {
1097         struct pi433_device     *device;
1098         int                     retval;
1099
1100         /* setup spi parameters */
1101         spi->mode = 0x00;
1102         spi->bits_per_word = 8;
1103         /*
1104          * spi->max_speed_hz = 10000000;
1105          * 1MHz already set by device tree overlay
1106          */
1107
1108         retval = spi_setup(spi);
1109         if (retval) {
1110                 dev_dbg(&spi->dev, "configuration of SPI interface failed!\n");
1111                 return retval;
1112         }
1113
1114         dev_dbg(&spi->dev,
1115                 "spi interface setup: mode 0x%2x, %d bits per word, %dhz max speed",
1116                 spi->mode, spi->bits_per_word, spi->max_speed_hz);
1117
1118         /* Ping the chip by reading the version register */
1119         retval = spi_w8r8(spi, 0x10);
1120         if (retval < 0)
1121                 return retval;
1122
1123         switch (retval) {
1124         case 0x24:
1125                 dev_dbg(&spi->dev, "found pi433 (ver. 0x%x)", retval);
1126                 break;
1127         default:
1128                 dev_dbg(&spi->dev, "unknown chip version: 0x%x", retval);
1129                 return -ENODEV;
1130         }
1131
1132         /* Allocate driver data */
1133         device = kzalloc(sizeof(*device), GFP_KERNEL);
1134         if (!device)
1135                 return -ENOMEM;
1136
1137         /* Initialize the driver data */
1138         device->spi = spi;
1139         device->rx_active = false;
1140         device->tx_active = false;
1141         device->interrupt_rx_allowed = false;
1142
1143         /* init rx buffer */
1144         device->rx_buffer = kmalloc(MAX_MSG_SIZE, GFP_KERNEL);
1145         if (!device->rx_buffer) {
1146                 retval = -ENOMEM;
1147                 goto RX_failed;
1148         }
1149
1150         /* init wait queues */
1151         init_waitqueue_head(&device->tx_wait_queue);
1152         init_waitqueue_head(&device->rx_wait_queue);
1153         init_waitqueue_head(&device->fifo_wait_queue);
1154
1155         /* init fifo */
1156         INIT_KFIFO(device->tx_fifo);
1157
1158         /* init mutexes and locks */
1159         mutex_init(&device->tx_fifo_lock);
1160         mutex_init(&device->rx_lock);
1161
1162         /* setup GPIO (including irq_handler) for the different DIOs */
1163         retval = setup_gpio(device);
1164         if (retval) {
1165                 dev_dbg(&spi->dev, "setup of GPIOs failed");
1166                 goto GPIO_failed;
1167         }
1168
1169         /* setup the radio module */
1170         retval = rf69_set_mode(spi, standby);
1171         if (retval < 0)
1172                 goto minor_failed;
1173         retval = rf69_set_data_mode(spi, DATAMODUL_MODE_PACKET);
1174         if (retval < 0)
1175                 goto minor_failed;
1176         retval = rf69_enable_amplifier(spi, MASK_PALEVEL_PA0);
1177         if (retval < 0)
1178                 goto minor_failed;
1179         retval = rf69_disable_amplifier(spi, MASK_PALEVEL_PA1);
1180         if (retval < 0)
1181                 goto minor_failed;
1182         retval = rf69_disable_amplifier(spi, MASK_PALEVEL_PA2);
1183         if (retval < 0)
1184                 goto minor_failed;
1185         retval = rf69_set_output_power_level(spi, 13);
1186         if (retval < 0)
1187                 goto minor_failed;
1188         retval = rf69_set_antenna_impedance(spi, fifty_ohm);
1189         if (retval < 0)
1190                 goto minor_failed;
1191
1192         /* determ minor number */
1193         retval = pi433_get_minor(device);
1194         if (retval) {
1195                 dev_dbg(&spi->dev, "get of minor number failed");
1196                 goto minor_failed;
1197         }
1198
1199         /* create device */
1200         device->devt = MKDEV(MAJOR(pi433_dev), device->minor);
1201         device->dev = device_create(pi433_class,
1202                                     &spi->dev,
1203                                     device->devt,
1204                                     device,
1205                                     "pi433.%d",
1206                                     device->minor);
1207         if (IS_ERR(device->dev)) {
1208                 pr_err("pi433: device register failed\n");
1209                 retval = PTR_ERR(device->dev);
1210                 goto device_create_failed;
1211         } else {
1212                 dev_dbg(device->dev,
1213                         "created device for major %d, minor %d\n",
1214                         MAJOR(pi433_dev),
1215                         device->minor);
1216         }
1217
1218         /* start tx thread */
1219         device->tx_task_struct = kthread_run(pi433_tx_thread,
1220                                              device,
1221                                              "pi433.%d_tx_task",
1222                                              device->minor);
1223         if (IS_ERR(device->tx_task_struct)) {
1224                 dev_dbg(device->dev, "start of send thread failed");
1225                 retval = PTR_ERR(device->tx_task_struct);
1226                 goto send_thread_failed;
1227         }
1228
1229         /* create cdev */
1230         device->cdev = cdev_alloc();
1231         if (!device->cdev) {
1232                 dev_dbg(device->dev, "allocation of cdev failed");
1233                 retval = -ENOMEM;
1234                 goto cdev_failed;
1235         }
1236         device->cdev->owner = THIS_MODULE;
1237         cdev_init(device->cdev, &pi433_fops);
1238         retval = cdev_add(device->cdev, device->devt, 1);
1239         if (retval) {
1240                 dev_dbg(device->dev, "register of cdev failed");
1241                 goto del_cdev;
1242         }
1243
1244         /* spi setup */
1245         spi_set_drvdata(spi, device);
1246
1247         return 0;
1248
1249 del_cdev:
1250         cdev_del(device->cdev);
1251 cdev_failed:
1252         kthread_stop(device->tx_task_struct);
1253 send_thread_failed:
1254         device_destroy(pi433_class, device->devt);
1255 device_create_failed:
1256         pi433_free_minor(device);
1257 minor_failed:
1258         free_gpio(device);
1259 GPIO_failed:
1260         kfree(device->rx_buffer);
1261 RX_failed:
1262         kfree(device);
1263
1264         return retval;
1265 }
1266
1267 static int pi433_remove(struct spi_device *spi)
1268 {
1269         struct pi433_device     *device = spi_get_drvdata(spi);
1270
1271         /* free GPIOs */
1272         free_gpio(device);
1273
1274         /* make sure ops on existing fds can abort cleanly */
1275         device->spi = NULL;
1276
1277         kthread_stop(device->tx_task_struct);
1278
1279         device_destroy(pi433_class, device->devt);
1280
1281         cdev_del(device->cdev);
1282
1283         pi433_free_minor(device);
1284
1285         kfree(device->rx_buffer);
1286         kfree(device);
1287
1288         return 0;
1289 }
1290
1291 static const struct of_device_id pi433_dt_ids[] = {
1292         { .compatible = "Smarthome-Wolf,pi433" },
1293         {},
1294 };
1295
1296 MODULE_DEVICE_TABLE(of, pi433_dt_ids);
1297
1298 static struct spi_driver pi433_spi_driver = {
1299         .driver = {
1300                 .name =         "pi433",
1301                 .owner =        THIS_MODULE,
1302                 .of_match_table = of_match_ptr(pi433_dt_ids),
1303         },
1304         .probe =        pi433_probe,
1305         .remove =       pi433_remove,
1306
1307         /*
1308          * NOTE:  suspend/resume methods are not necessary here.
1309          * We don't do anything except pass the requests to/from
1310          * the underlying controller.  The refrigerator handles
1311          * most issues; the controller driver handles the rest.
1312          */
1313 };
1314
1315 /*-------------------------------------------------------------------------*/
1316
1317 static int __init pi433_init(void)
1318 {
1319         int status;
1320
1321         /*
1322          * If MAX_MSG_SIZE is smaller then FIFO_SIZE, the driver won't
1323          * work stable - risk of buffer overflow
1324          */
1325         if (MAX_MSG_SIZE < FIFO_SIZE)
1326                 return -EINVAL;
1327
1328         /*
1329          * Claim device numbers.  Then register a class
1330          * that will key udev/mdev to add/remove /dev nodes.  Last, register
1331          * Last, register the driver which manages those device numbers.
1332          */
1333         status = alloc_chrdev_region(&pi433_dev, 0, N_PI433_MINORS, "pi433");
1334         if (status < 0)
1335                 return status;
1336
1337         pi433_class = class_create(THIS_MODULE, "pi433");
1338         if (IS_ERR(pi433_class)) {
1339                 unregister_chrdev(MAJOR(pi433_dev),
1340                                   pi433_spi_driver.driver.name);
1341                 return PTR_ERR(pi433_class);
1342         }
1343
1344         status = spi_register_driver(&pi433_spi_driver);
1345         if (status < 0) {
1346                 class_destroy(pi433_class);
1347                 unregister_chrdev(MAJOR(pi433_dev),
1348                                   pi433_spi_driver.driver.name);
1349         }
1350
1351         return status;
1352 }
1353
1354 module_init(pi433_init);
1355
1356 static void __exit pi433_exit(void)
1357 {
1358         spi_unregister_driver(&pi433_spi_driver);
1359         class_destroy(pi433_class);
1360         unregister_chrdev(MAJOR(pi433_dev), pi433_spi_driver.driver.name);
1361 }
1362 module_exit(pi433_exit);
1363
1364 MODULE_AUTHOR("Marcus Wolf, <[email protected]>");
1365 MODULE_DESCRIPTION("Driver for Pi433");
1366 MODULE_LICENSE("GPL");
1367 MODULE_ALIAS("spi:pi433");