1 files changed, 59 insertions, 0 deletions
diff --git a/src/stm32/spi.c b/src/stm32/spi.c
new file mode 100644
index 00000000..77072958
--- /dev/null
+++ b/src/stm32/spi.c
@@ -0,0 +1,59 @@
+// SPI functions on STM32
+//
+// Copyright (C) 2019  Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#include "command.h" // shutdown
+#include "gpio.h" // spi_setup
+#include "internal.h" // gpio_peripheral
+#include "sched.h" // sched_shutdown
+
+DECL_ENUMERATION("spi_bus", "spi2", 0);
+DECL_CONSTANT_STR("BUS_PINS_spi2", "PB14,PB15,PB13");
+
+struct spi_config
+spi_setup(uint32_t bus, uint8_t mode, uint32_t rate)
+{
+    if (bus)
+        shutdown("Invalid spi bus");
+
+    // Enable SPI
+    if (!is_enabled_pclock(SPI2_BASE)) {
+        enable_pclock(SPI2_BASE);
+        gpio_peripheral(GPIO('B', 14), GPIO_FUNCTION(5), 1);
+        gpio_peripheral(GPIO('B', 15), GPIO_FUNCTION(5), 0);
+        gpio_peripheral(GPIO('B', 13), GPIO_FUNCTION(5), 0);
+    }
+
+    // Calculate CR1 register
+    uint32_t pclk = get_pclock_frequency(SPI2_BASE);
+    uint32_t div = 0;
+    while ((pclk >> (div + 1)) > rate && div < 7)
+        div++;
+    uint32_t cr1 = ((mode << SPI_CR1_CPHA_Pos) | (div << SPI_CR1_BR_Pos)
+                    | SPI_CR1_SPE | SPI_CR1_MSTR | SPI_CR1_SSM | SPI_CR1_SSI);
+
+    return (struct spi_config){ .spi_cr1 = cr1 };
+}
+
+void
+spi_prepare(struct spi_config config)
+{
+    SPI2->CR1 = config.spi_cr1;
+}
+
+void
+spi_transfer(struct spi_config config, uint8_t receive_data,
+             uint8_t len, uint8_t *data)
+{
+    while (len--) {
+        SPI2->DR = *data;
+        while (!(SPI2->SR & SPI_SR_RXNE))
+            ;
+        uint8_t rdata = SPI2->DR;
+        if (receive_data)
+            *data = rdata;
+        data++;
+    }
+}