1 files changed, 176 insertions, 0 deletions
diff --git a/drivers/avr/spi_master.c b/drivers/avr/spi_master.c
new file mode 100644
index 000000000..32cc55c83
--- /dev/null
+++ b/drivers/avr/spi_master.c
@@ -0,0 +1,176 @@
+/*  Copyright 2020
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program 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 General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <avr/io.h>
+
+#include "spi_master.h"
+#include "quantum.h"
+#include "timer.h"
+
+#if defined(__AVR_ATmega16U2__) || defined(__AVR_ATmega32U2__) || defined(__AVR_ATmega16U4__) || defined(__AVR_ATmega32U4__) || defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB647__) || defined(__AVR_AT90USB1286__) || defined(__AVR_AT90USB1287__)
+#    define SPI_SCK_PIN B1
+#    define SPI_MOSI_PIN B2
+#    define SPI_MISO_PIN B3
+#elif defined(__AVR_ATmega32A__)
+#    define SPI_SCK_PIN B7
+#    define SPI_MOSI_PIN B5
+#    define SPI_MISO_PIN B6
+#elif defined(__AVR_ATmega328P__)
+#    define SPI_SCK_PIN B5
+#    define SPI_MOSI_PIN B3
+#    define SPI_MISO_PIN B4
+#endif
+
+#ifndef SPI_TIMEOUT
+#    define SPI_TIMEOUT 100
+#endif
+
+static pin_t   currentSlavePin    = NO_PIN;
+static uint8_t currentSlaveConfig = 0;
+static bool    currentSlave2X     = false;
+
+void spi_init(void) {
+    writePinHigh(SPI_SS_PIN);
+    setPinOutput(SPI_SCK_PIN);
+    setPinOutput(SPI_MOSI_PIN);
+    setPinInput(SPI_MISO_PIN);
+
+    SPCR = (_BV(SPE) | _BV(MSTR));
+}
+
+bool spi_start(pin_t slavePin, bool lsbFirst, uint8_t mode, uint16_t divisor) {
+    if (currentSlavePin != NO_PIN || slavePin == NO_PIN) {
+        return false;
+    }
+
+    currentSlaveConfig = 0;
+
+    if (lsbFirst) {
+        currentSlaveConfig |= _BV(DORD);
+    }
+
+    switch (mode) {
+        case 1:
+            currentSlaveConfig |= _BV(CPHA);
+            break;
+        case 2:
+            currentSlaveConfig |= _BV(CPOL);
+            break;
+        case 3:
+            currentSlaveConfig |= (_BV(CPOL) | _BV(CPHA));
+            break;
+    }
+
+    uint16_t roundedDivisor = 1;
+    while (roundedDivisor < divisor) {
+        roundedDivisor <<= 1;
+    }
+
+    switch (roundedDivisor) {
+        case 16:
+            currentSlaveConfig |= _BV(SPR0);
+            break;
+        case 64:
+            currentSlaveConfig |= _BV(SPR1);
+            break;
+        case 128:
+            currentSlaveConfig |= (_BV(SPR1) | _BV(SPR0));
+            break;
+        case 2:
+            currentSlave2X = true;
+            break;
+        case 8:
+            currentSlave2X = true;
+            currentSlaveConfig |= _BV(SPR0);
+            break;
+        case 32:
+            currentSlave2X = true;
+            currentSlaveConfig |= _BV(SPR1);
+            break;
+    }
+
+    SPCR |= currentSlaveConfig;
+    if (currentSlave2X) {
+        SPSR |= _BV(SPI2X);
+    }
+    currentSlavePin = slavePin;
+    setPinOutput(currentSlavePin);
+    writePinLow(currentSlavePin);
+
+    return true;
+}
+
+spi_status_t spi_write(uint8_t data) {
+    SPDR = data;
+
+    uint16_t timeout_timer = timer_read();
+    while (!(SPSR & _BV(SPIF))) {
+        if ((timer_read() - timeout_timer) >= SPI_TIMEOUT) {
+            return SPI_STATUS_TIMEOUT;
+        }
+    }
+
+    return SPDR;
+}
+
+spi_status_t spi_read() {
+    SPDR = 0x00;  // Dummy
+
+    uint16_t timeout_timer = timer_read();
+    while (!(SPSR & _BV(SPIF))) {
+        if ((timer_read() - timeout_timer) >= SPI_TIMEOUT) {
+            return SPI_STATUS_TIMEOUT;
+        }
+    }
+
+    return SPDR;
+}
+
+spi_status_t spi_transmit(const uint8_t *data, uint16_t length) {
+    spi_status_t status = SPI_STATUS_ERROR;
+
+    for (uint16_t i = 0; i < length; i++) {
+        status = spi_write(data[i]);
+    }
+
+    return status;
+}
+
+spi_status_t spi_receive(uint8_t *data, uint16_t length) {
+    spi_status_t status = SPI_STATUS_ERROR;
+
+    for (uint16_t i = 0; i < length; i++) {
+        status = spi_read();
+
+        if (status > 0) {
+            data[i] = status;
+        }
+    }
+
+    return (status < 0) ? status : SPI_STATUS_SUCCESS;
+}
+
+void spi_stop(void) {
+    if (currentSlavePin != NO_PIN) {
+        setPinOutput(currentSlavePin);
+        writePinHigh(currentSlavePin);
+        currentSlavePin = NO_PIN;
+        SPSR &= ~(_BV(SPI2X));
+        SPCR &= ~(currentSlaveConfig);
+        currentSlaveConfig = 0;
+        currentSlave2X     = false;
+    }
+}