C++ refactoring, plus low-power support, plus software-based SPI CS

I'm backlogged.

SpiDriver.cpp

@@ -0,0 +1,118 @@
+/*
+ * Copyright (C) 2019  Max Regan
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "SpiDriver.h"
+#include "macros.h"
+
+namespace BSP {
+
+using RC = Common::ReturnCode;
+using Common::Schedule::TaskScheduler;
+using Common::Schedule::NextTime;
+using Common::Time;
+
+SpiDriver::SpiDriver(TaskScheduler &scheduler)
+    : m_scheduler(scheduler)
+    , m_spi(SPI1)
+{}
+
+void SpiDriver::init()
+{
+    SET(RCC->IOPENR, RCC_IOPENR_IOPAEN);
+    RCC->APB2ENR |= RCC_APB2ENR_SPI1EN;
+
+    /* Assign SPI_MOSI to PA12 (AFRH5), since PA7 is taken by LPTIM_OUT */
+    GPIOA->AFR[1] &= ~GPIO_AFRH_AFRH4;
+
+    SET_TO(GPIOA->MODER, GPIO_MODER_MODE12, 2u << GPIO_MODER_MODE12_Pos);
+
+    GPIOA->OTYPER &= ~GPIO_OTYPER_OT_12;
+    GPIOA->PUPDR &= ~GPIO_PUPDR_PUPD12;
+
+    // SPI1 NSS (PA4)
+    //GPIOA->AFR[0] &= ~GPIO_AFRL_AFRL4;
+
+    SET_TO(GPIOA->MODER, GPIO_MODER_MODE4, 1u << GPIO_MODER_MODE4_Pos);
+
+    GPIOA->OTYPER &= ~GPIO_OTYPER_OT_4;
+    GPIOA->PUPDR &= ~GPIO_PUPDR_PUPD4;
+    // enable pullup, since the pin doesn't seem to stay up
+    GPIOA->PUPDR |= 2u << GPIO_PUPDR_PUPD4_Pos;
+
+    // SPI1 SCK (PA5)
+    GPIOA->AFR[0] &= ~GPIO_AFRL_AFRL5;
+
+    SET_TO(GPIOA->MODER, GPIO_MODER_MODE5, 2u << GPIO_MODER_MODE5_Pos);
+
+    GPIOA->OTYPER &= ~GPIO_OTYPER_OT_5;
+    GPIOA->PUPDR &= ~GPIO_PUPDR_PUPD5;
+
+    // SPI1 MISO (PA6)
+    GPIOA->AFR[0] &= ~GPIO_AFRL_AFRL6;
+
+    SET_TO(GPIOA->MODER, GPIO_MODER_MODE6, 2u << GPIO_MODER_MODE6_Pos);
+
+    GPIOA->OTYPER &= ~GPIO_OTYPER_OT_6;
+    GPIOA->PUPDR &= ~GPIO_PUPDR_PUPD6;
+
+    // Enable Master mode and half the baud rate, so it's set to ~1MHz
+    m_spi->CR1 |= SPI_CR1_MSTR | SPI_CR1_LSBFIRST | SPI_CR1_SSM;
+    m_spi->CR1 |= 1u << SPI_CR1_BR_Pos;
+    m_spi->CR2 |= SPI_CR2_SSOE;
+}
+
+NextTime SpiDriver::execute()
+{
+    return NextTime::never();
+}
+
+RC SpiDriver::tx_blocking(const uint8_t *data, size_t len)
+{
+    if (len <= 0) {
+      return RC::FAIL;
+    }
+
+    m_spi->CR1 |= SPI_CR1_SPE;
+
+    //FLIP(GPIOB->ODR, GPIO_ODR_OD3);
+    CLR(m_spi->CR1, SPI_CR1_SSI);
+    SET(GPIOA->ODR, GPIO_ODR_OD4);
+
+    for (size_t i = 0; i < len; i++) {
+        while (!(m_spi->SR & SPI_SR_TXE)) {}
+        m_spi->DR = data[i];
+    }
+
+    //FLIP(GPIOB->ODR, GPIO_ODR_OD3);
+
+    while (!(m_spi->SR & SPI_SR_TXE)) {}
+
+    // Ensure that NSS is held for long enough to meet the display's thSCS
+    for (int i = 0; i < 4; i++);
+
+    m_spi->CR1 &= ~SPI_CR1_SPE;
+    SET(m_spi->CR1, SPI_CR1_SSI);
+    CLR(GPIOA->ODR, GPIO_ODR_OD4);
+
+    return RC::OK;
+}
+
+}