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// Serial Peripheral Interface (SPI) support
//
// Copyright (C) 2016-2018 Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU GPLv3 license.
#include "autoconf.h" // CONFIG_MACH_atmega644p
#include "command.h" // shutdown
#include "gpio.h" // spi_setup
#include "internal.h" // GPIO
#include "pgm.h" // READP
#include "sched.h" // sched_shutdown
DECL_ENUMERATION("spi_bus", "spi", 0);
#if CONFIG_MACH_atmega168 || CONFIG_MACH_atmega328 || CONFIG_MACH_atmega328p
static const uint8_t MISO = GPIO('B', 4), MOSI = GPIO('B', 3);
static const uint8_t SCK = GPIO('B', 5), SS = GPIO('B', 2);
DECL_CONSTANT_STR("BUS_PINS_spi", "PB4,PB3,PB5");
#elif CONFIG_MACH_atmega644p || CONFIG_MACH_atmega1284p
static const uint8_t MISO = GPIO('B', 6), MOSI = GPIO('B', 5);
static const uint8_t SCK = GPIO('B', 7), SS = GPIO('B', 4);
DECL_CONSTANT_STR("BUS_PINS_spi", "PB6,PB5,PB7");
#elif CONFIG_MACH_at90usb1286 || CONFIG_MACH_at90usb646 \
|| CONFIG_MACH_atmega32u4 || CONFIG_MACH_atmega1280 \
|| CONFIG_MACH_atmega2560
static const uint8_t MISO = GPIO('B', 3), MOSI = GPIO('B', 2);
static const uint8_t SCK = GPIO('B', 1), SS = GPIO('B', 0);
DECL_CONSTANT_STR("BUS_PINS_spi", "PB3,PB2,PB1");
#endif
static void
spi_init(void)
{
if (!(GPIO2REGS(SS)->mode & GPIO2BIT(SS)))
// The SS pin must be an output pin (but is otherwise unused)
gpio_out_setup(SS, 0);
gpio_out_setup(SCK, 0);
gpio_out_setup(MOSI, 0);
gpio_in_setup(MISO, 0);
SPCR = (1<<MSTR) | (1<<SPE);
SPSR = 0;
}
struct spi_config
spi_setup(uint32_t bus, uint8_t mode, uint32_t rate)
{
if (bus)
shutdown("Invalid spi_setup parameters");
// Make sure the SPI interface is enabled
spi_init();
// Setup rate
struct spi_config config = {0, 0};
if (rate >= (CONFIG_CLOCK_FREQ / 2)) {
config.spsr = (1<<SPI2X);
} else if (rate >= (CONFIG_CLOCK_FREQ / 4)) {
config.spcr = 0;
} else if (rate >= (CONFIG_CLOCK_FREQ / 8)) {
config.spcr = 1;
config.spsr = (1<<SPI2X);
} else if (rate >= (CONFIG_CLOCK_FREQ / 16)) {
config.spcr = 1;
} else if (rate >= (CONFIG_CLOCK_FREQ / 32)) {
config.spcr = 2;
config.spsr = (1<<SPI2X);
} else if (rate >= (CONFIG_CLOCK_FREQ / 64)) {
config.spcr = 2;
} else {
config.spcr = 3;
}
// Setup mode
config.spcr |= (1<<SPE) | (1<<MSTR) | (mode << CPHA);
return config;
}
void
spi_prepare(struct spi_config config)
{
SPCR = config.spcr;
SPSR = config.spsr;
}
void
spi_transfer(struct spi_config config, uint8_t receive_data
, uint8_t len, uint8_t *data)
{
if (receive_data) {
while (len--) {
SPDR = *data;
while (!(SPSR & (1<<SPIF)))
;
*data++ = SPDR;
}
} else {
while (len--) {
SPDR = *data++;
while (!(SPSR & (1<<SPIF)))
;
}
}
}
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