spi_master for AVR (#8299)

* Change _delay_ms/us() to wait_ms/us()

* Switch to platform-agnostic GPIO macros

* Add AVR spi_master and migrate Adafruit BLE code

* Set verbose back to false

* Add clock divisor, bit order and SPI mode configuration for init

* Add start and stop functions

* Move configuration of mode, endianness and speed to `spi_start()`

* Some breaks here would be good

* Default Adafruit BLE clock divisor to 4 (2MHz on the Feather 32U4)

* Remove mode and divisor enums

* Add some docs

* No hr at EOF

* Add links in sidebar

1 files changed, 57 insertions, 0 deletions

diff --git a/drivers/avr/spi_master.h b/drivers/avr/spi_master.h
new file mode 100644
index 000000000..0bab2dc24
--- /dev/null
+++ b/drivers/avr/spi_master.h
@@ -0,0 +1,57 @@
+/*  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/>.
+ */
+
+#pragma once
+
+#include "quantum.h"
+
+typedef int16_t spi_status_t;
+
+// Hardware SS pin is defined in the header so that user code can refer to it
+#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_SS_PIN B0
+#elif defined(__AVR_ATmega32A__)
+#    define SPI_SS_PIN B4
+#elif defined(__AVR_ATmega328P__)
+#    define SPI_SS_PIN B2
+#endif
+
+#define SPI_STATUS_SUCCESS (0)
+#define SPI_STATUS_ERROR (-1)
+#define SPI_STATUS_TIMEOUT (-2)
+
+#define SPI_TIMEOUT_IMMEDIATE (0)
+#define SPI_TIMEOUT_INFINITE (0xFFFF)
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+void spi_init(void);
+
+void spi_start(pin_t slavePin, bool lsbFirst, uint8_t mode, uint8_t divisor);
+
+spi_status_t spi_write(uint8_t data, uint16_t timeout);
+
+spi_status_t spi_read(uint16_t timeout);
+
+spi_status_t spi_transmit(const uint8_t *data, uint16_t length, uint16_t timeout);
+
+spi_status_t spi_receive(uint8_t *data, uint16_t length, uint16_t timeout);
+
+void spi_stop(void);
+#ifdef __cplusplus
+}
+#endif