libpinedio-usb.c

// SPDX-License-Identifier: GPL-2.0-or-later
/**
 * Copyright (C) 2024 Marek Kraus <gamelaster@outlook.com>
 *
 * This code is heavily based on ch341a_spi.c from the flashrom project.
 * The plan is to rework parts of code, but until that, original developers deserves to be mentioned.
 * Copyright (C) 2011 asbokid <ballymunboy@gmail.com>
 * Copyright (C) 2014 Pluto Yang <yangyj.ee@gmail.com>
 * Copyright (C) 2015-2016 Stefan Tauner
 * Copyright (C) 2015 Urja Rannikko <urjaman@gmail.com>
 */

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include "libpinedio-usb.h"

#if 0
#define pinedio_mutex_lock(...) { printf("Locking %s\n", __func__); pthread_mutex_lock(__VA_ARGS__); }
#define pinedio_mutex_unlock(...) { printf("Unlocking %s\n", __func__); pthread_mutex_unlock(__VA_ARGS__); }
#else
#define pinedio_mutex_lock(...) pthread_mutex_lock(__VA_ARGS__);
#define pinedio_mutex_unlock(...) pthread_mutex_unlock(__VA_ARGS__);
#endif

#define CH341_USB_TIMEOUT 1000
#define CH341_WRITE_EP 0x02
#define CH341_READ_EP 0x82
#define	CH341_PACKET_LENGTH	0x20

#define CH341_CMD_SPI_STREAM 0xA8

#define CH341_CMD_UIO_STREAM 0xAB
#define CH341_CMD_UIO_STM_OUT 0x80
#define CH341_CMD_UIO_STM_DIR 0x40
#define CH341_CMD_UIO_STM_END 0x20

#define MIN(x, y) (((x) < (y)) ? (x) : (y))

enum trans_state {TRANS_ACTIVE = -2, TRANS_ERR = -1, TRANS_IDLE = 0};

static void platform_sleep(uint32_t msecs) {
#ifdef __WIN32
  Sleep(msecs);
#else
  usleep(msecs * 1000);
#endif
}

static void cb_common(const char* func, struct libusb_transfer *transfer) {
  int* transfer_cnt = (int *) transfer->user_data;

  if (transfer->status == LIBUSB_TRANSFER_CANCELLED) {
    // Silently ACK and exit.
    *transfer_cnt = TRANS_IDLE;
    return;
  }

  if (transfer->status != LIBUSB_TRANSFER_COMPLETED) {
    fprintf(stderr, "%s: error: %s\n", func, libusb_error_name(transfer->status));
    *transfer_cnt = TRANS_ERR;
  } else {
    *transfer_cnt = transfer->actual_length;
  }
}

// callback for bulk out async transfer
static void LIBUSB_CALL cb_out(struct libusb_transfer *transfer) {
  cb_common(__func__, transfer);
}

// callback for bulk in async transfer
static void LIBUSB_CALL cb_in(struct libusb_transfer *transfer) {
  cb_common(__func__, transfer);
}

static int32_t usb_transfer(struct pinedio_inst *inst, const char *func, unsigned int writecnt, unsigned int readcnt,
                            const uint8_t *writearr, uint8_t *readarr, bool lock)
{
  int state_out = TRANS_IDLE;
  inst->transfer_out->buffer = (uint8_t*)writearr;
  inst->transfer_out->length = writecnt;
  inst->transfer_out->user_data = &state_out;

  if (lock) {
    pinedio_mutex_lock(&inst->usb_access_mutex);
  }

  /* Schedule write first */
  if (writecnt > 0) {
    state_out = TRANS_ACTIVE;
    int ret = libusb_submit_transfer(inst->transfer_out);
    if (ret) {
      fprintf(stderr, "%s: failed to submit OUT transfer: %s\n", func, libusb_error_name(ret));
      state_out = TRANS_ERR;
      goto err;
    }
  }

  /* Handle all asynchronous packets as long as we have stuff to write or read. The write(s) simply need
   * to complete but we need to scheduling reads as long as we are not done. */
  unsigned int free_idx = 0; /* The IN transfer we expect to be free next. */
  unsigned int in_idx = 0; /* The IN transfer we expect to be completed next. */
  unsigned int in_done = 0;
  unsigned int in_active = 0;
  unsigned int out_done = 0;
  uint8_t *in_buf = readarr;
  int state_in[USB_IN_TRANSFERS] = {0};
  do {
    /* Schedule new reads as long as there are free transfers and unscheduled bytes to read. */
    while ((in_done + in_active) < readcnt && state_in[free_idx] == TRANS_IDLE) {
      unsigned int cur_todo = MIN(CH341_PACKET_LENGTH - 1, readcnt - in_done - in_active);
      inst->transfer_ins[free_idx]->length = cur_todo;
      inst->transfer_ins[free_idx]->buffer = in_buf;
      inst->transfer_ins[free_idx]->user_data = &state_in[free_idx];
      int ret = libusb_submit_transfer(inst->transfer_ins[free_idx]);
      if (ret) {
        state_in[free_idx] = TRANS_ERR;
        fprintf(stderr, "%s: failed to submit IN transfer: %s\n",
                 func, libusb_error_name(ret));
        goto err;
      }
      in_buf += cur_todo;
      in_active += cur_todo;
      state_in[free_idx] = TRANS_ACTIVE;
      free_idx = (free_idx + 1) % USB_IN_TRANSFERS; /* Increment (and wrap around). */
    }

    /* Actually get some work done. */
    libusb_handle_events_timeout(NULL, &(struct timeval){1, 0});

    /* Check for the write */
    if (out_done < writecnt) {
      if (state_out == TRANS_ERR) {
        goto err;
      } else if (state_out > 0) {
        out_done += state_out;
        state_out = TRANS_IDLE;
      }
    }
    /* Check for completed transfers. */
    while (state_in[in_idx] != TRANS_IDLE && state_in[in_idx] != TRANS_ACTIVE) {
      if (state_in[in_idx] == TRANS_ERR) {
        goto err;
      }
      /* If a transfer is done, record the number of bytes read and reuse it later. */
      in_done += state_in[in_idx];
      in_active -= state_in[in_idx];
      state_in[in_idx] = TRANS_IDLE;
      in_idx = (in_idx + 1) % USB_IN_TRANSFERS; /* Increment (and wrap around). */
    }
  } while ((out_done < writecnt) || (in_done < readcnt));

  if (lock) {
    pinedio_mutex_unlock(&inst->usb_access_mutex);
  }
  return 0;
err:
  /* Clean up on errors. */
  fprintf(stderr, "%s: Failed to %s %d bytes\n", func, (state_out == TRANS_ERR) ? "write" : "read",
           (state_out == TRANS_ERR) ? writecnt : readcnt);
  /* First, we must cancel any ongoing requests and wait for them to be canceled. */
  if ((writecnt > 0) && (state_out == TRANS_ACTIVE)) {
    if (libusb_cancel_transfer(inst->transfer_out) != 0)
      state_out = TRANS_ERR;
  }
  if (readcnt > 0) {
    unsigned int i;
    for (i = 0; i < USB_IN_TRANSFERS; i++) {
      if (state_in[i] == TRANS_ACTIVE)
        if (libusb_cancel_transfer(inst->transfer_ins[i]) != 0)
          state_in[i] = TRANS_ERR;
    }
  }

  /* Wait for cancellations to complete. */
  while (1) {
    bool finished = true;
    if ((writecnt > 0) && (state_out == TRANS_ACTIVE))
      finished = false;
    if (readcnt > 0) {
      unsigned int i;
      for (i = 0; i < USB_IN_TRANSFERS; i++) {
        if (state_in[i] == TRANS_ACTIVE)
          finished = false;
      }
    }
    if (finished)
      break;
    libusb_handle_events_timeout(NULL, &(struct timeval){1, 0});
  }
  if (lock) {
    pinedio_mutex_unlock(&inst->usb_access_mutex);
  }
  return -1;
}

static uint8_t reverse_byte(uint8_t x) {
  x = ((x >> 1) & 0x55) | ((x << 1) & 0xaa);
  x = ((x >> 2) & 0x33) | ((x << 2) & 0xcc);
  x = ((x >> 4) & 0x0f) | ((x << 4) & 0xf0);

  return x;
}

int32_t pinedio_set_cs(struct pinedio_inst *inst, bool active) {
  uint8_t buf[] = {
          CH341_CMD_UIO_STREAM,
          CH341_CMD_UIO_STM_DIR | 0x3f,
          CH341_CMD_UIO_STM_OUT | (active ? 0x36 : 0x37),
          CH341_CMD_UIO_STM_END
  };

  int32_t ret = usb_transfer(inst, __func__, sizeof(buf), 0, buf, NULL, true);
  if (ret < 0) {
    printf("Failed to set CS pin.\n");
  }
  return ret;
}

int32_t pinedio_write_read(struct pinedio_inst* inst, uint8_t *writearr, uint32_t writecnt, uint8_t* readarr, uint32_t readcnt) {
  /* How many packets ... */
  const size_t packets = (writecnt + readcnt + CH341_PACKET_LENGTH - 2) / (CH341_PACKET_LENGTH - 1);

  /* We pluck CS/timeout handling into the first packet thus we need to allocate one extra package. */
  uint8_t wbuf[packets*CH341_PACKET_LENGTH];
  uint8_t rbuf[writecnt + readcnt];
  /* Initialize the write buffer to zero to prevent writing random stack contents to device. */
  memset(wbuf, 0, CH341_PACKET_LENGTH);

  uint8_t *ptr = wbuf;
  /* CS usage is optimized by doing both transitions in one packet.
   * Final transition to deselected state is in the pin disable. */
//  pluck_cs(ptr, &data->stored_delay_us);
  if (inst->options[PINEDIO_OPTION_AUTO_CS]) {
    pinedio_set_cs(inst, true);
  }
  unsigned int write_left = writecnt;
  unsigned int read_left = readcnt;
  unsigned int p;
  for (p = 0; p < packets; p++) {
    unsigned int write_now = MIN(CH341_PACKET_LENGTH - 1, write_left);
    unsigned int read_now = MIN((CH341_PACKET_LENGTH - 1) - write_now, read_left);
    ptr = &wbuf[p*CH341_PACKET_LENGTH];
    *ptr++ = CH341_CMD_SPI_STREAM;
    unsigned int i;
    for (i = 0; i < write_now; ++i)
      *ptr++ = reverse_byte(*writearr++);
    if (read_now) {
      memset(ptr, 0xFF, read_now);
      read_left -= read_now;
    }
    write_left -= write_now;
  }

  int32_t ret = usb_transfer(inst, __func__, packets + writecnt + readcnt,
                             writecnt + readcnt, wbuf, rbuf, true);
  if (inst->options[PINEDIO_OPTION_AUTO_CS]) {
    pinedio_set_cs(inst, false);
  }
  if (ret < 0)
    return -1;

  unsigned int i;
  for (i = 0; i < readcnt; i++) {
    *readarr++ = reverse_byte(rbuf[writecnt + i]);
  }

  return 0;
}

int32_t pinedio_transceive(struct pinedio_inst* inst, uint8_t *write_buf, uint8_t* read_buf, uint32_t count) {
  const size_t packets = (count + CH341_PACKET_LENGTH - 2) / (CH341_PACKET_LENGTH - 1);

  uint8_t wbuf[packets*CH341_PACKET_LENGTH];


  uint8_t *ptr = wbuf;
  if (inst->options[PINEDIO_OPTION_AUTO_CS]) {
    pinedio_set_cs(inst, true);
  }
  unsigned int write_left = count;
  unsigned int read_left = count;
  unsigned int p;
  for (p = 0; p < packets; p++) {
    unsigned int write_now = MIN(CH341_PACKET_LENGTH - 1, write_left);
    unsigned int read_now = MIN((CH341_PACKET_LENGTH - 1) - write_now, read_left);
    ptr = &wbuf[p*CH341_PACKET_LENGTH];
    *ptr++ = CH341_CMD_SPI_STREAM;
    unsigned int i;
    for (i = 0; i < write_now; ++i)
      *ptr++ = reverse_byte(*write_buf++);
    if (read_now) {
      memset(ptr, 0xFF, read_now);
      read_left -= read_now;
    }
    write_left -= write_now;
  }

  int32_t ret = usb_transfer(inst, __func__, packets + count,
                             count, wbuf, read_buf, true);
  if (inst->options[PINEDIO_OPTION_AUTO_CS]) {
    pinedio_set_cs(inst, false);
  }
  if (ret < 0)
    return -1;

  unsigned int i;
  for (i = 0; i < count; i++) {
    *read_buf++ = reverse_byte(*read_buf);
  }

  return 0;
}

int32_t pinedio_init(struct pinedio_inst *inst, void *driver) {
  int32_t ret;
  inst->int_running_cnt = 0;
  inst->pin_poll_thread_exit = false;
  for (int i = 0; i < PINEDIO_INT_PIN_MAX; i++) {
    inst->interrupts[i].callback = NULL;
  }

  inst->options[PINEDIO_OPTION_AUTO_CS] = 1;

  ret = pthread_mutex_init(&inst->usb_access_mutex, NULL);
  if (ret != 0) {
    fprintf(stderr, "Failed to initialize mutex, res: %d.\n", ret);
    return -1;
  }

  ret = libusb_init(NULL);
  if (ret < 0) {
    fprintf(stderr, "Couldn't initialize libusb!\n");
    return -1;
  }

  libusb_set_option(NULL, LIBUSB_OPTION_LOG_LEVEL, LIBUSB_LOG_LEVEL_INFO);
  uint16_t vid = 0x1A86;
  uint16_t pid = 0x5512;
  inst->handle = libusb_open_device_with_vid_pid(NULL, vid, pid);
  if (inst->handle == NULL) {
    // TODO: Rework this so we can receive error and print it.
    fprintf(stderr, "Couldn't open LoRa Adapator device.\n");
    return -2;
  }

#ifdef __linux__
  // On Windows, driver needs to be replaced manually by Zadig
  ret = libusb_detach_kernel_driver(inst->handle, 0);
  if (ret != 0 && ret != LIBUSB_ERROR_NOT_FOUND) {
    fprintf(stderr, "Cannot detach the existing USB driver. Claiming the interface may fail: %s\n",
            libusb_error_name(ret));
  }
#endif

  ret = libusb_claim_interface(inst->handle, 0);
  if (ret != 0) {
    fprintf(stderr, "Failed to claim interface 0: %s\n", libusb_error_name(ret));
    goto deinit_on_error;
  }

  // Allocate and pre-fill transfer structures.
  inst->transfer_out = libusb_alloc_transfer(0);
  if (!inst->transfer_out) {
    fprintf(stderr, "Failed to alloc libusb OUT transfer.\n");
    goto deinit_on_error;
  }
  for (int i = 0; i < USB_IN_TRANSFERS; i++) {
    inst->transfer_ins[i] = libusb_alloc_transfer(0);
    if (inst->transfer_ins[i] == NULL) {
      fprintf(stderr, "Failed to alloc libusb IN transfer %d.\n", i);
      goto deinit_on_error;
    }
  }

  // We use these helpers but don't fill the actual buffer yet.
  libusb_fill_bulk_transfer(inst->transfer_out, inst->handle, CH341_WRITE_EP, NULL, 0, cb_out, NULL, CH341_USB_TIMEOUT);
  for (int i = 0; i < USB_IN_TRANSFERS; i++)
    libusb_fill_bulk_transfer(inst->transfer_ins[i], inst->handle, CH341_READ_EP, NULL, 0, cb_in, NULL,
                              CH341_USB_TIMEOUT);

  /**
   * We don't need to initialize SPI at all, as by default it's configured properly.
   * Only thing required is pinmux, what is anyway configured by CS change function.
   */

  pinedio_set_cs(inst, false);

  return 0;

deinit_on_error:
  pinedio_deinit(inst);
  return ret;
}

void pinedio_deinit(struct pinedio_inst *inst) {
  pinedio_mutex_lock(&inst->usb_access_mutex);
  if (inst->int_running_cnt != 0) {
    inst->pin_poll_thread_exit = true;
    pinedio_mutex_unlock(&inst->usb_access_mutex);
    pthread_join(inst->pin_poll_thread, NULL);
  } else {
    pinedio_mutex_unlock(&inst->usb_access_mutex);
  }

  for (int i = 0; i < USB_IN_TRANSFERS; i++) {
    if (inst->transfer_ins[i] != NULL) {
      libusb_free_transfer(inst->transfer_ins[i]);
    }
  }
  if (inst->transfer_out != NULL) {
    libusb_free_transfer(inst->transfer_out);
  }
  
  if (inst->handle != NULL) {
    // We don't know if claim of interface was successful, but libusb handles this.
    libusb_release_interface(inst->handle, 0);
#ifdef __linux__
    libusb_attach_kernel_driver(inst->handle, 0);
#endif
    libusb_close(inst->handle);
  }
}

static int32_t pinedio_get_input(struct pinedio_inst *inst, uint32_t* input)
{
  uint8_t buf[] = {
    0xA0,
  };
  uint8_t output[6];

  int32_t ret = usb_transfer(inst, __func__, sizeof(buf), sizeof(output), buf, output, true);
  if (ret < 0) {
    fprintf(stderr, "Could not get input pins.\n");
  }
  *input = ((output[2] & 0x80) << 16) | ((output[1] & 0xef) << 8) | output[0];
  return ret;
}

int32_t pinedio_get_irq_state(struct pinedio_inst *inst) {
  uint32_t input;
  int32_t ret = pinedio_get_input(inst, &input);
  if (ret != 0) {
    return ret;
  }
  return (input & (1 << 10)) != 0 ? 1 : 0;
}

static void* pinedio_pin_poll_thread(void* arg) {
  struct pinedio_inst *inst = arg;
  int32_t ret = 0;
  bool should_exit = false;
  uint32_t pin_masks[PINEDIO_INT_PIN_MAX];
  pin_masks[PINEDIO_INT_PIN_IRQ] = 1 << 10;

  uint32_t input;
//  pin_masks[PINEDIO_INT_PIN_BUSY] = 10 << 1;
  while (!should_exit) {
    ret = pinedio_get_input(inst, &input);
    pinedio_mutex_lock(&inst->usb_access_mutex);
    if (ret != 0) continue;
    for (uint8_t int_pin = 0; int_pin < PINEDIO_INT_PIN_MAX; int_pin++) {
      struct pinedio_inst_int* inst_int = &inst->interrupts[int_pin];
      if (inst_int->callback == NULL) continue;
      uint8_t state = (input & pin_masks[int_pin]) != 0;
      if (inst_int->previous_state != 255 && inst_int->previous_state != state) {
        enum pinedio_int_mode mode =
                inst_int->previous_state == false && state == true ? PINEDIO_INT_MODE_RISING : PINEDIO_INT_MODE_FALLING;
        if (inst_int->mode & mode) {
          pinedio_mutex_unlock(&inst->usb_access_mutex);
          inst_int->callback();
          pinedio_mutex_lock(&inst->usb_access_mutex);
        }
      }
      inst_int->previous_state = state;
    }

    should_exit = inst->pin_poll_thread_exit;
    pinedio_mutex_unlock(&inst->usb_access_mutex);
    platform_sleep(1000 / 30);
  }
}

int32_t
pinedio_attach_interrupt(struct pinedio_inst *inst, enum pinedio_int_pin int_pin, enum pinedio_int_mode int_mode,
                         void (*callback)(void)) {
  int32_t res = 0;
  // TODO: Add check if int_pin is correct
  pinedio_mutex_lock(&inst->usb_access_mutex);
  if (inst->interrupts[int_pin].callback != NULL) {
    inst->int_running_cnt--;
  }
  inst->interrupts[int_pin].previous_state = 255;
  inst->interrupts[int_pin].mode = int_mode;
  inst->interrupts[int_pin].callback = callback;
  if (inst->int_running_cnt == 0) {
    inst->pin_poll_thread_exit = false;
    res = pthread_create(&inst->pin_poll_thread, NULL, pinedio_pin_poll_thread, inst);
    if (res != 0) {
      fprintf(stderr, "Failed to create thread, res: %d\n", res);
      goto unlock;
    }
  }

unlock:
  pinedio_mutex_unlock(&inst->usb_access_mutex);
  return res;
}

int32_t pinedio_deattach_interrupt(struct pinedio_inst *inst, enum pinedio_int_pin int_pin) {
  // TODO: Add check if int_pin is correct
  pinedio_mutex_lock(&inst->usb_access_mutex);
  int32_t res;
  if (inst->int_running_cnt == 0 || inst->interrupts[int_pin].callback == NULL) {
    res = -1;
    goto unlock;
  }
  inst->interrupts[int_pin].callback = NULL;
  inst->int_running_cnt--;
  if (inst->int_running_cnt == 0) {
    inst->pin_poll_thread_exit = true;
    pinedio_mutex_unlock(&inst->usb_access_mutex);
    pthread_join(inst->pin_poll_thread, NULL);
    return 0;
  }
unlock:
  pinedio_mutex_unlock(&inst->usb_access_mutex);
  return res;
}

int32_t pinedio_set_option(struct pinedio_inst *inst, enum pinedio_option option, uint32_t value) {
  inst->options[option] = value;
}