gps/soc/software/bsp/drivers/pmod_spi.c

#include "bsp/pmod_spi.h"

#include "bsp/mmio.h"
#include "bsp/soc.h"

#define PMOD_SPI_CTRL  (BSP_PMOD_SPI_BASE + 0x00u)
#define PMOD_SPI_TX    (BSP_PMOD_SPI_BASE + 0x04u)
#define PMOD_SPI_RX    (BSP_PMOD_SPI_BASE + 0x08u)
#define PMOD_SPI_READY (BSP_PMOD_SPI_BASE + 0x0cu)

#define PMOD_SPI_CTRL_BUSY 0x1u
#define PMOD_SPI_CTRL_CSN  0x2u
#define PMOD_SPI_CTRL_QUAD 0x4u

static uint32_t pmod_spi_ctrl_shadow = PMOD_SPI_CTRL_CSN;
static uint32_t pmod_spi_cs_setup_us;
static uint32_t pmod_spi_inter_byte_us;
static uint32_t pmod_spi_cs_hold_us;
static uint32_t pmod_spi_cs_inactive_us;

static void pmod_spi_delay_us(uint32_t us)
{
  if (us == 0u) {
    return;
  }

  const uint64_t ticks =
      ((uint64_t)BSP_CLINT_TIMEBASE_HZ * us + 999999u) / 1000000u;
  const uint64_t start = bsp_read64(BSP_CLINT_MTIME);
  while ((bsp_read64(BSP_CLINT_MTIME) - start) < ticks) {
  }
}

static void pmod_spi_wait_ready(void)
{
  while ((bsp_read32(PMOD_SPI_READY) & 1u) == 0u) {
  }
  while ((bsp_read32(PMOD_SPI_CTRL) & PMOD_SPI_CTRL_BUSY) != 0u) {
  }
}

static void pmod_spi_write_ctrl(uint32_t ctrl)
{
  pmod_spi_wait_ready();
  pmod_spi_ctrl_shadow = ctrl & (PMOD_SPI_CTRL_CSN | PMOD_SPI_CTRL_QUAD);
  bsp_write32(PMOD_SPI_CTRL, pmod_spi_ctrl_shadow);
}

void bsp_pmod_spi_init(void)
{
  pmod_spi_write_ctrl(PMOD_SPI_CTRL_CSN);
}

void bsp_pmod_spi_set_mode(bsp_pmod_spi_mode_t mode)
{
  uint32_t ctrl = pmod_spi_ctrl_shadow & ~PMOD_SPI_CTRL_QUAD;
  if (mode == BSP_PMOD_SPI_MODE_QUAD) {
    ctrl |= PMOD_SPI_CTRL_QUAD;
  }
  pmod_spi_write_ctrl(ctrl);
}

bsp_pmod_spi_mode_t bsp_pmod_spi_mode(void)
{
  return (pmod_spi_ctrl_shadow & PMOD_SPI_CTRL_QUAD) != 0u
      ? BSP_PMOD_SPI_MODE_QUAD
      : BSP_PMOD_SPI_MODE_SINGLE;
}

void bsp_pmod_spi_set_quad(int enabled)
{
  bsp_pmod_spi_set_mode(enabled ? BSP_PMOD_SPI_MODE_QUAD : BSP_PMOD_SPI_MODE_SINGLE);
}

void bsp_pmod_spi_set_timing(uint32_t cs_setup_us,
                             uint32_t inter_byte_us,
                             uint32_t cs_hold_us,
                             uint32_t cs_inactive_us)
{
  pmod_spi_cs_setup_us = cs_setup_us;
  pmod_spi_inter_byte_us = inter_byte_us;
  pmod_spi_cs_hold_us = cs_hold_us;
  pmod_spi_cs_inactive_us = cs_inactive_us;
}

void bsp_pmod_spi_select(void)
{
  pmod_spi_write_ctrl(pmod_spi_ctrl_shadow & ~PMOD_SPI_CTRL_CSN);
}

void bsp_pmod_spi_deselect(void)
{
  pmod_spi_write_ctrl(pmod_spi_ctrl_shadow | PMOD_SPI_CTRL_CSN);
}

int bsp_pmod_spi_ready(void)
{
  return ((bsp_read32(PMOD_SPI_READY) & 1u) != 0u) &&
         ((bsp_read32(PMOD_SPI_CTRL) & PMOD_SPI_CTRL_BUSY) == 0u);
}

uint32_t bsp_pmod_spi_ctrl(void)
{
  return bsp_read32(PMOD_SPI_CTRL);
}

uint32_t bsp_pmod_spi_rx(void)
{
  return bsp_read32(PMOD_SPI_RX);
}

uint8_t bsp_pmod_spi_xfer8(uint8_t value)
{
  pmod_spi_wait_ready();
  bsp_pmod_spi_set_mode(BSP_PMOD_SPI_MODE_SINGLE);
  bsp_write32(PMOD_SPI_TX, ((uint32_t)value) << 24);
  pmod_spi_wait_ready();
  return (uint8_t)(bsp_read32(PMOD_SPI_RX) & 0xffu);
}

uint32_t bsp_pmod_spi_xfer32(uint32_t value)
{
  pmod_spi_wait_ready();
  bsp_pmod_spi_set_mode(BSP_PMOD_SPI_MODE_QUAD);
  bsp_write32(PMOD_SPI_TX, value);
  pmod_spi_wait_ready();
  return bsp_read32(PMOD_SPI_RX);
}

void bsp_pmod_spi_transfer(const uint8_t *tx, uint8_t *rx, size_t len)
{
  for (size_t i = 0; i < len; ++i) {
    uint8_t out = tx ? tx[i] : 0xffu;
    uint8_t in = bsp_pmod_spi_xfer8(out);
    if (rx) {
      rx[i] = in;
    }
  }
}

void bsp_pmod_spi_transaction(const uint8_t *tx, uint8_t *rx, size_t len)
{
  if (len == 0u) {
    return;
  }

  bsp_pmod_spi_select();
  pmod_spi_delay_us(pmod_spi_cs_setup_us);

  for (size_t i = 0; i < len; ++i) {
    const uint8_t out = tx ? tx[i] : 0xffu;
    const uint8_t in = bsp_pmod_spi_xfer8(out);
    if (rx) {
      rx[i] = in;
    }
    if ((i + 1u) < len) {
      pmod_spi_delay_us(pmod_spi_inter_byte_us);
    }
  }

  pmod_spi_delay_us(pmod_spi_cs_hold_us);
  bsp_pmod_spi_deselect();
  pmod_spi_delay_us(pmod_spi_cs_inactive_us);
}

void bsp_pmod_spi_write_reg8(uint8_t command, uint8_t value)
{
  const uint8_t tx[2] = {command, value};
  bsp_pmod_spi_transaction(tx, NULL, sizeof(tx));
}

void bsp_pmod_spi_read_regs(uint8_t command,
                            uint8_t dummy,
                            uint8_t *data,
                            size_t len)
{
  if ((data == NULL) || (len == 0u)) {
    return;
  }

  bsp_pmod_spi_select();
  pmod_spi_delay_us(pmod_spi_cs_setup_us);

  (void)bsp_pmod_spi_xfer8(command);
  pmod_spi_delay_us(pmod_spi_inter_byte_us);

  for (size_t i = 0; i < len; ++i) {
    data[i] = bsp_pmod_spi_xfer8(dummy);
    if ((i + 1u) < len) {
      pmod_spi_delay_us(pmod_spi_inter_byte_us);
    }
  }

  pmod_spi_delay_us(pmod_spi_cs_hold_us);
  bsp_pmod_spi_deselect();
  pmod_spi_delay_us(pmod_spi_cs_inactive_us);
}

uint8_t bsp_pmod_spi_read_reg8(uint8_t command, uint8_t dummy)
{
  uint8_t value = 0xffu;
  bsp_pmod_spi_read_regs(command, dummy, &value, 1u);
  return value;
}