/*
 * This file is part of the libopencm3 project.
 *
 * Copyright (C) 2009 Uwe Hermann <uwe@hermann-uwe.de>
 * Copyright (C) 2013 Stephen Dwyer <scdwyer@ualberta.ca>
 *
 * This library is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <libopencm3/stm32/rcc.h>
#include <libopencm3/stm32/gpio.h>
#include <libopencm3/stm32/usart.h>
#include <libopencm3/stm32/dma.h>
#include <libopencm3/cm3/nvic.h>
#include <libopencm3/stm32/spi.h>
#include <stdio.h>
#include <errno.h>

int _write(int file, char *ptr, int len);

static void clock_setup(void)
{
	rcc_clock_setup_in_hse_12mhz_out_72mhz();

	/* Enable GPIOA, GPIOB, GPIOC clock. */
	rcc_peripheral_enable_clock(&RCC_APB2ENR,
				    RCC_APB2ENR_IOPAEN | RCC_APB2ENR_IOPBEN |
				    RCC_APB2ENR_IOPCEN);

	/* Enable clocks for GPIO port A (for GPIO_USART2_TX) and USART2. */
	rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_IOPAEN |
				    RCC_APB2ENR_AFIOEN);
	rcc_peripheral_enable_clock(&RCC_APB1ENR, RCC_APB1ENR_USART2EN);

	/* Enable SPI1 Periph and gpio clocks */
	rcc_peripheral_enable_clock(&RCC_APB2ENR,
				    RCC_APB2ENR_SPI1EN);

}

static void spi_setup(void) {

  /* Configure GPIOs: SS=PA4, SCK=PA5, MISO=PA6 and MOSI=PA7 */
  gpio_set_mode(GPIOA, GPIO_MODE_OUTPUT_50_MHZ,
            GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO4 |
            								GPIO5 |
                                            GPIO7 );

  gpio_set_mode(GPIOA, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT,
          GPIO6);

  /* Reset SPI, SPI_CR1 register cleared, SPI is disabled */
  spi_reset(SPI1);

  /* Set up SPI in Master mode with:
   * Clock baud rate: 1/64 of peripheral clock frequency
   * Clock polarity: Idle High
   * Clock phase: Data valid on 2nd clock pulse
   * Data frame format: 8-bit
   * Frame format: MSB First
   */
  spi_init_master(SPI1, SPI_CR1_BAUDRATE_FPCLK_DIV_64, SPI_CR1_CPOL_CLK_TO_1_WHEN_IDLE,
                  SPI_CR1_CPHA_CLK_TRANSITION_2, SPI_CR1_DFF_8BIT, SPI_CR1_MSBFIRST);

  /*
   * Set NSS management to software.
   *
   * Note:
   * Setting nss high is very important, even if we are controlling the GPIO
   * ourselves this bit needs to be at least set to 1, otherwise the spi
   * peripheral will not send any data out.
   */
  spi_enable_software_slave_management(SPI1);
  spi_set_nss_high(SPI1);

  /* Enable SPI1 periph. */
  spi_enable(SPI1);
}

static void usart_setup(void)
{
	/* Setup GPIO pin GPIO_USART2_TX and GPIO_USART2_RX. */
	gpio_set_mode(GPIOA, GPIO_MODE_OUTPUT_50_MHZ,
		      GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO_USART2_TX);
	gpio_set_mode(GPIOA, GPIO_MODE_INPUT,
		      GPIO_CNF_INPUT_FLOAT, GPIO_USART2_RX);

	/* Setup UART parameters. */
	usart_set_baudrate(USART2, 9600);
	usart_set_databits(USART2, 8);
	usart_set_stopbits(USART2, USART_STOPBITS_1);
	usart_set_mode(USART2, USART_MODE_TX_RX);
	usart_set_parity(USART2, USART_PARITY_NONE);
	usart_set_flow_control(USART2, USART_FLOWCONTROL_NONE);

	/* Finally enable the USART. */
	usart_enable(USART2);
}

int _write(int file, char *ptr, int len)
{
	int i;

	if (file == 1) {
		for (i = 0; i < len; i++)
			usart_send_blocking(USART2, ptr[i]);
		return i;
	}

	errno = EIO;
	return -1;
}

static void gpio_setup(void)
{
	/* Set GPIO8 (in GPIO port A) to 'output push-pull'. */
	gpio_set_mode(GPIOA, GPIO_MODE_OUTPUT_2_MHZ,
		      GPIO_CNF_OUTPUT_PUSHPULL, GPIO8);
}

int main(void)
{
	int counter = 0;
	u16 rx_value = 0x42;

	clock_setup();
	gpio_setup();
	usart_setup();
	spi_setup();


	/* Blink the LED (PA8) on the board with every transmitted byte. */
	while (1) {
		/* LED on/off */
		gpio_toggle(GPIOA, GPIO8);

		/* printf the value that SPI should send */
		printf("Counter: %i  SPI Sent Byte: %i", counter, (uint8_t) counter);
		/* blocking send of the byte out SPI1 */
		spi_send(SPI1, (uint8_t) counter);
		/* Read the byte that just came in (use a loopback between MISO and MOSI
		 * to get the same byte back)
		 */
		rx_value = spi_read(SPI1);
		/* printf the byte just received */
		printf("    SPI Received Byte: %i\r\n", rx_value);

		counter++;
		
	}

	return 0;
}