#include "bsp/spi_flash.h"

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

#define SPI_CTRL  (BSP_SPI_BASE + 0x00u)
#define SPI_TX    (BSP_SPI_BASE + 0x04u)
#define SPI_RX    (BSP_SPI_BASE + 0x08u)
#define SPI_READY (BSP_SPI_BASE + 0x0cu)

#define SPI_CTRL_BUSY 0x1u
#define SPI_CTRL_CSN  0x2u

static void delay_cycles(uint32_t cycles)
{
  for (volatile uint32_t i = 0; i < cycles; ++i) {
    asm volatile ("" ::: "memory");
  }
}

static void spi_wait_ready(void)
{
  while ((bsp_read32(SPI_READY) & 1u) == 0u) {
  }
  while ((bsp_read32(SPI_CTRL) & SPI_CTRL_BUSY) != 0u) {
  }
}

static void spi_select(int selected)
{
  spi_wait_ready();
  bsp_write32(SPI_CTRL, selected ? 0u : SPI_CTRL_CSN);
}

static uint8_t spi_xfer8(uint8_t value)
{
  spi_wait_ready();
  bsp_write32(SPI_TX, ((uint32_t)value) << 24);
  spi_wait_ready();
  return (uint8_t)(bsp_read32(SPI_RX) & 0xffu);
}

static void flash_cmd(uint8_t cmd)
{
  spi_select(1);
  (void)spi_xfer8(cmd);
  spi_select(0);
}

void bsp_spi_flash_init(void)
{
  bsp_write32(SPI_CTRL, SPI_CTRL_CSN);
}

void bsp_spi_flash_reset(void)
{
  spi_select(0);
  flash_cmd(0x66u);
  delay_cycles(1000);
  flash_cmd(0x99u);
  delay_cycles(200000);
}

uint32_t bsp_spi_flash_read_id(void)
{
  uint32_t id = 0;
  spi_select(1);
  (void)spi_xfer8(0x9fu);
  id |= ((uint32_t)spi_xfer8(0u)) << 16;
  id |= ((uint32_t)spi_xfer8(0u)) << 8;
  id |= (uint32_t)spi_xfer8(0u);
  spi_select(0);
  return id;
}

void bsp_spi_flash_read(uint32_t flash_addr, void *dst, uint32_t len)
{
  uint8_t *out = (uint8_t *)dst;

  spi_select(1);
  (void)spi_xfer8(0x13u);
  (void)spi_xfer8((uint8_t)(flash_addr >> 24));
  (void)spi_xfer8((uint8_t)(flash_addr >> 16));
  (void)spi_xfer8((uint8_t)(flash_addr >> 8));
  (void)spi_xfer8((uint8_t)flash_addr);
  for (uint32_t i = 0; i < len; ++i) {
    out[i] = spi_xfer8(0u);
  }
  spi_select(0);
}