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