gadget-tester/spi.c

/* 
 * (c) danielinux 2019
 *
 *      GPLv.2
 *
 * See LICENSE for details
 */
#include <stdint.h>
#include "spi_drv.h"
#include "system.h"

void spi_cs_off(void)
{
    GPIOA_BSRR |= (1 << SPI_FLASH_PIN);
    DMB();
    while(!(GPIOA_ODR & (1 << SPI_FLASH_PIN)))
        ;
}

void spi_cs_on(void)
{
    volatile int i;
    GPIOA_BSRR |= (1 << (SPI_FLASH_PIN + 16));
    DMB();
    while(GPIOA_ODR & (1 << SPI_FLASH_PIN))
        ;
}


static void spi_flash_pin_setup(void)
{
    uint32_t reg;
    AHB1_CLOCK_ER |= GPIOA_AHB1_CLOCK_ER;
    reg = GPIOA_MODE & ~ (0x03 << (SPI_FLASH_PIN * 2));
    GPIOA_MODE = reg | (1 << (SPI_FLASH_PIN * 2));

    reg = GPIOA_PUPD & (0x03 <<  (SPI_FLASH_PIN * 2));
    GPIOA_PUPD = reg | (0x01 << (SPI_FLASH_PIN * 2));

    reg = GPIOA_OSPD & ~(0x03 << (SPI_FLASH_PIN * 2));
    GPIOA_OSPD |= (0x03 << (SPI_FLASH_PIN * 2));

}

static void spi1_pins_setup(void)
{
    uint32_t reg;
    AHB1_CLOCK_ER |= GPIOA_AHB1_CLOCK_ER;
    /* Set mode = AF */
    reg = GPIOA_MODE & ~ (0x03 << (SPI1_CLOCK_PIN * 2));
    GPIOA_MODE = reg | (2 << (SPI1_CLOCK_PIN * 2));
    reg = GPIOA_MODE & ~ (0x03 << (SPI1_MOSI_PIN * 2));
    GPIOA_MODE = reg | (2 << (SPI1_MOSI_PIN * 2));
    reg = GPIOA_MODE & ~ (0x03 << (SPI1_MISO_PIN * 2));
    GPIOA_MODE = reg | (2 << (SPI1_MISO_PIN * 2));

    /* Alternate function: use low pins (5,6,7) */
    reg = GPIOA_AFL & ~(0xf << ((SPI1_CLOCK_PIN) * 4));
    GPIOA_AFL = reg | (SPI1_PIN_AF << ((SPI1_CLOCK_PIN) * 4));
    reg = GPIOA_AFL & ~(0xf << ((SPI1_MOSI_PIN) * 4));
    GPIOA_AFL = reg | (SPI1_PIN_AF << ((SPI1_MOSI_PIN) * 4));
    reg = GPIOA_AFL & ~(0xf << ((SPI1_MISO_PIN) * 4));
    GPIOA_AFL = reg | (SPI1_PIN_AF << ((SPI1_MISO_PIN) * 4));

}

static void spi1_reset(void)
{
    APB2_CLOCK_RST |= SPI1_APB2_CLOCK_ER_VAL;
    APB2_CLOCK_RST &= ~SPI1_APB2_CLOCK_ER_VAL;
}

uint8_t spi_read(void)
{
    volatile uint32_t reg;
    do {
        reg = SPI1_SR;
    } while(!(reg & SPI_SR_RX_NOTEMPTY));
    return (uint8_t)SPI1_DR;
}

void spi_write(const char byte)
{
    int i;
    volatile uint32_t reg;
    do {
        reg = SPI1_SR;
    } while ((reg & SPI_SR_TX_EMPTY) == 0);
    SPI1_DR = byte;
    do {
        reg = SPI1_SR;
    } while ((reg & SPI_SR_TX_EMPTY) == 0);
}


void spi_init(int polarity, int phase)
{
    spi1_pins_setup();
    spi_flash_pin_setup();
    APB2_CLOCK_ER |= SPI1_APB2_CLOCK_ER_VAL;
    spi1_reset();
	SPI1_CR1 = SPI_CR1_MASTER | (5 << 3) | (polarity << 1) | (phase << 0);
	SPI1_CR2 |= SPI_CR2_SSOE;
    SPI1_CR1 |= SPI_CR1_SPI_EN;
}