#define _GNU_SOURCE
#include <stdint.h>
#include <stdlib.h>

#include <libopencm3/stm32/gpio.h>
#include <libopencm3/stm32/spi.h>
#include <libopencm3/stm32/usart.h>

#include <spi.h>

static int stm32f1_spi_tx_rx(struct spi_dev *dev, void *rx_buf, size_t rx_len,
	const void *tx_buf, size_t tx_len);

static struct spi_ops stm32f1_spi_ops = {
	.tx_rx = stm32f1_spi_tx_rx,
};

static void stm32f1_spi_init(void)
{
	spi_reset(SPI1);
	spi_init_master(SPI1,
		SPI_CR1_BAUDRATE_FPCLK_DIV_2,
		SPI_CR1_CPOL_CLK_TO_0_WHEN_IDLE,
		SPI_CR1_CPHA_CLK_TRANSITION_1,
		SPI_CR1_DFF_8BIT,
		SPI_CR1_MSBFIRST);
	spi_enable_software_slave_management(SPI1);
	spi_set_nss_high(SPI1);
	spi_enable(SPI1);

	gpio_set(GPIOA, GPIO_SPI1_NSS);
}

struct spi_dev *spi_probe(void)
{
	struct spi_dev *dev;

	if (!(dev = malloc(sizeof *dev)))
		return NULL;

	dev->ops = &stm32f1_spi_ops;
	dev->dev_id = SPI1;

	stm32f1_spi_init();

	return dev;
}

void spi_release(struct spi_dev *dev)
{
	free(dev);
}

static int stm32f1_spi_tx_rx(struct spi_dev *dev, void *rx_buf, size_t rx_len,
	const void *tx_buf, size_t tx_len)
{
	char *rx = rx_buf;
	const char *tx = tx_buf;
	size_t i;

	gpio_clear(GPIOA, GPIO_SPI1_NSS);

	for (i = 0; i < tx_len; ++i) {
		spi_send(dev->dev_id, *tx++);
		(void)spi_read(dev->dev_id);
	}

	if (rx_buf) {
		for (i = 0; i < rx_len; ++i) {
			spi_send(dev->dev_id, 0);
			*rx++ = spi_read(dev->dev_id);
		}
	}

	gpio_set(GPIOA, GPIO_SPI1_NSS);

	return 0;
}