#include "kern/dma/dma_manager.h"

#include "arch/stm32l4xxx/peripherals/dma.h"
#include "arch/stm32l4xxx/peripherals/rcc.h"
#include "arch/stm32l4xxx/peripherals/spi.h"
#include "arch/stm32l4xxx/peripherals/usart.h"

/* Bitmask of DMA2 channels in use. */
uint8_t dma_inuse[2];

void (*dma_channel_callbacks[14])(void*);
void* callback_args[14];

#define ON_DMA(dma, chan)                                    \
  void on_dma##dma##_channel##chan()                         \
  {                                                          \
    if (dma_channel_callbacks[(dma - 1) * 7 + (chan - 1)]) { \
      dma_channel_callbacks[(dma - 1) * 7 + (chan - 1)](     \
          callback_args[(dma - 1) * 7 + (chan - 1)]);        \
    }                                                        \
  }

ON_DMA(1, 1);
ON_DMA(1, 2);
ON_DMA(1, 3);
ON_DMA(1, 4);
ON_DMA(1, 5);
ON_DMA(1, 6);
ON_DMA(1, 7);
ON_DMA(2, 1);
ON_DMA(2, 2);
ON_DMA(2, 3);
ON_DMA(2, 4);
ON_DMA(2, 5);
ON_DMA(2, 6);
ON_DMA(2, 7);

static inline dma_t* get_dma(int dma)
{
  if (dma) {
    return &DMA2;
  } else {
    return &DMA1;
  }
}

static dma_t* get_raw_dma(dma_channel_t chan)
{
  return get_dma(chan.dma);
}

static dma_channel_config_t* get_raw_channel_config(dma_channel_t chan)
{
  dma_t* dma = get_raw_dma(chan);
  return &dma->channel_config[chan.chan];
}

static uint32_t get_periph_location(dma_peripheral_t operipheral)
{
#define CASE(p, n) \
  case p:          \
    return ptr2reg(n);
  switch (operipheral) {
    CASE(DMA1_PERIPH_USART1_RX, &USART1.rd_r)
    CASE(DMA1_PERIPH_USART1_TX, &USART1.td_r)
    CASE(DMA1_PERIPH_USART2_RX, &USART2.rd_r)
    CASE(DMA1_PERIPH_USART2_TX, &USART2.td_r)
    CASE(DMA2_PERIPH_SPI1_RX, &SPI1.d_r)
    CASE(DMA2_PERIPH_SPI1_TX, &SPI1.d_r)
    CASE(DMA1_PERIPH_SPI1_RX, &SPI1.d_r)
    CASE(DMA1_PERIPH_SPI1_TX, &SPI1.d_r)
    CASE(DMA2_PERIPH_SPI3_RX, &SPI3.d_r)
    CASE(DMA2_PERIPH_SPI3_TX, &SPI3.d_r)

    default:
      return 0;
  };
#undef CASE
}

static dma_channel_t allocate_dma_channel(
    dma_peripheral_t operipheral, int* modesel)
{
  dma_peripheral_t peripheral = operipheral & 0xff;
  int dmasel = peripheral >= DMA2_DMA1_SWITCH__;
  if (dmasel) {
    peripheral -= DMA2_DMA1_SWITCH__;
  }
  int chan = peripheral % DMA_N_CHANNELS;

  *modesel = peripheral / 7;
  return (dma_channel_t){.dma = dmasel, .chan = chan};
}

/*
 * Atomically reserves the DMA channel so other calls
 * cannot erroneously reserve the same DMA channel.
 *
 * Returns 0 if this function was unable to reserve
 * the channel.
 */
static int try_reserve_dma_channel(dma_channel_t chan)
{
  int in_use = __sync_fetch_and_or(&dma_inuse[chan.dma], 1 << chan.chan);

  return !(in_use & (1 << chan.chan));
}

void release_dma_channel(dma_channel_t chan)
{
  dma_channel_config_t* config = get_raw_channel_config(chan);
  regset(config->cc_r, dma_cc_en, 0);       /* Disable the register. */
  dma_inuse[chan.dma] &= ~(1 << chan.chan); /* Release the DMA. */

  if (!dma_inuse[chan.dma]) {
    /* Power-down the DMA if not in use. */
    if (chan.dma) {
      regset(RCC.ahb1en_r, rcc_dma2en, 0);
    } else {
      regset(RCC.ahb1en_r, rcc_dma1en, 0);
    }
  }
}

void configure_dma_channel(
    dma_channel_t chan,
    dma_peripheral_t operipheral,
    dma_opts_t* opts,
    dma_dir_t dir,
    int selmode,
    bool mem2mem,
    int* error_out)
{
  if (chan.dma) {
    regset(RCC.ahb1en_r, rcc_dma2en, 1);
  } else {
    regset(RCC.ahb1en_r, rcc_dma1en, 1);
  }

  dma_t* dma = get_raw_dma(chan);
  regset(dma->csel_r, 0xF << (4 * chan.chan), selmode);
  dma_channel_config_t* config = &dma->channel_config[chan.chan];

  uint32_t reg = 0;

  regset(reg, dma_cc_dir, dir);
  regset(reg, dma_cc_tcie, opts->transfer_complete_interrupt_enable);
  regset(reg, dma_cc_htie, opts->half_transfer_interrupt_enable);
  regset(reg, dma_cc_teie, opts->transfer_error_interrupt_enable);
  regset(reg, dma_cc_circ, opts->circular_mode);
  regset(reg, dma_cc_pinc, opts->peripheral_increment);
  regset(reg, dma_cc_minc, opts->memory_increment);
  regset(reg, dma_cc_psize, opts->peripheral_block_size);
  regset(reg, dma_cc_msize, opts->memory_block_size);
  regset(reg, dma_cc_pl, opts->priority);
  regset(reg, dma_cc_mem2mem, mem2mem);

  config->cc_r = reg;
  config->cpa_r = get_periph_location(operipheral);

  *error_out = 0;
}

dma_mem2mem_channel_t select_dma_channel_mem2mem(
    int channel, dma_opts_t* opts, int* error_out)
{
#define WRAP(c) ((dma_mem2mem_channel_t){.c_ = c})
  // TODO this should probably be in a critical section.
  dma_channel_t chan;
  if (channel == -1) {
    chan.dma = 1;
    if ((dma_inuse[chan.dma] & 0x7F) == 0x7F) {
      chan.dma = 0;
    }

    if ((dma_inuse[chan.dma] & 0x7F) == 0x7F) {
      *error_out = DMA_ERROR_CHANNEL_IN_USE;
      return WRAP(DMA_CHAN_ERROR);
    }

    uint8_t t = ~(dma_inuse[chan.dma] << 1);
    chan.chan = 6 - (__builtin_clz(t) - 24);
  } else {
    if (channel < 7) {
      chan.dma = 0;
      chan.chan = channel;
    } else {
      chan.dma = 0;
      chan.chan = channel - 7;
    }
  }

  if (!try_reserve_dma_channel(chan)) {
    *error_out = DMA_ERROR_CHANNEL_IN_USE;
    return WRAP(DMA_CHAN_ERROR);
  }

  int ec = 0;
  configure_dma_channel(
      chan,
      -1 /* No peripheral */,
      opts,
      READ_FROM_PERIPHERAL,
      /* selmode = */ 0x8,
      /* mem2mem = */ true,
      &ec);

  if (ec) {
    *error_out = ec;
    return WRAP(DMA_CHAN_ERROR);
  }

  *error_out = 0;
  return WRAP(chan);
#undef WRAP
}

dma_mem2p_channel_t select_dma_channel_mem2p(
    dma_peripheral_t peripheral, dma_opts_t* opts_in, int* error_out)
{
#define WRAP(c) ((dma_mem2p_channel_t){.c_ = c})
  *error_out = 0;

  int modesel;
  dma_channel_t ret = allocate_dma_channel(peripheral, &modesel);

  if (!try_reserve_dma_channel(ret)) {
    *error_out = DMA_ERROR_CHANNEL_IN_USE;
    return WRAP(DMA_CHAN_ERROR);
  }

  configure_dma_channel(
      ret,
      peripheral,
      opts_in,
      READ_FROM_MEMORY,
      modesel,
      /* mem2mem = */ false,
      error_out);

  if (*error_out) {
    return WRAP(DMA_CHAN_ERROR);
  }

  *error_out = 0;
  return WRAP(ret);
#undef WRAP
}

dma_p2mem_channel_t select_dma_channel_p2mem(
    dma_peripheral_t peripheral, dma_opts_t* opts_in, int* error_out)
{
#define WRAP(c) ((dma_p2mem_channel_t){.c_ = c})
  *error_out = 0;

  int modesel;
  dma_channel_t ret = allocate_dma_channel(peripheral, &modesel);

  if (!try_reserve_dma_channel(ret)) {
    *error_out = DMA_ERROR_CHANNEL_IN_USE;
    return WRAP(DMA_CHAN_ERROR);
  }

  configure_dma_channel(
      ret,
      peripheral,
      opts_in,
      READ_FROM_PERIPHERAL,
      modesel,
      /* mem2mem = */ false,
      error_out);

  if (*error_out) {
    return WRAP(DMA_CHAN_ERROR);
  }

  *error_out = 0;
  return WRAP(ret);
#undef WRAP
}

void dma_mem2p_initiate_transfer(
    dma_mem2p_channel_t chan, const void* from_loc, uint16_t nblocks)
{
  dma_channel_config_t* config = get_raw_channel_config(chan.c_);
  config->cma_r = ptr2reg(from_loc);
  config->cndt_r = nblocks;

  regset(config->cc_r, dma_cc_en, 1);
}

void dma_mem2mem_initiate_transfer(
    dma_mem2mem_channel_t chan,
    void* to_loc,
    const void* from_loc,
    uint16_t nblocks)
{
  dma_channel_config_t* config = get_raw_channel_config(chan.c_);
  config->cma_r = ptr2reg(to_loc);
  config->cpa_r = ptr2reg(from_loc);
  config->cndt_r = nblocks;

  regset(config->cc_r, dma_cc_en, 1);
}

void dma_p2mem_initiate_transfer(
    dma_p2mem_channel_t chan, void* to_loc, uint16_t nblocks)
{
  dma_channel_config_t* config = get_raw_channel_config(chan.c_);

  config->cma_r = ptr2reg(to_loc);
  config->cndt_r = nblocks;

  regset(config->cc_r, dma_cc_en, 1);
}

void dma_chan_set_callback(
    dma_channel_t chan, void (*callback)(void*), void* arg)
{
  dma_channel_callbacks[chan.dma * 7 + chan.chan] = callback;
  callback_args[chan.dma * 7 + chan.chan] = arg;
  enable_interrupt(dma_channel_get_interrupt(chan));
}

void dma_channel_interrupt_enable(dma_channel_t chan, bool enabled)
{
  dma_channel_config_t* config = get_raw_channel_config(chan);
  regset(config->cc_r, dma_cc_tcie, !!enabled);
  if (enabled) {
    enable_interrupt(dma_channel_get_interrupt(chan));
  } else {
    disable_interrupt(dma_channel_get_interrupt(chan));
  }
}

interrupt_t dma_channel_get_interrupt(dma_channel_t chan)
{
  if (chan.dma == 0) {
    return IRQ_DMA1_CHANNEL1_IRQ + chan.chan;
  } else {
    switch (chan.chan) {
      case 5:
        return IRQ_DMA1_CHANNEL6_IRQ;
      case 6:
        return IRQ_DMA1_CHANNEL7_IRQ;
      default:
        return IRQ_DMA2_CHANNEL1_IRQ + chan.chan;
    }
  }
}