501 lines
11 KiB
C
501 lines
11 KiB
C
/*
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* Copyright (c) 2017 Google LLC.
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#define LOG_LEVEL CONFIG_SPI_LOG_LEVEL
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#include <logging/log.h>
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LOG_MODULE_REGISTER(spi_sam0);
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#include "spi_context.h"
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#include <errno.h>
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#include <device.h>
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#include <spi.h>
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#include <soc.h>
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/* Device constant configuration parameters */
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struct spi_sam0_config {
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SercomSpi *regs;
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u32_t pads;
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u32_t pm_apbcmask;
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u16_t gclk_clkctrl_id;
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};
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/* Device run time data */
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struct spi_sam0_data {
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struct spi_context ctx;
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};
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static void wait_synchronization(SercomSpi *regs)
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{
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#if defined(SERCOM_SPI_SYNCBUSY_MASK)
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/* SYNCBUSY is a register */
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while ((regs->SYNCBUSY.reg & SERCOM_SPI_SYNCBUSY_MASK) != 0) {
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}
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#elif defined(SERCOM_SPI_STATUS_SYNCBUSY)
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/* SYNCBUSY is a bit */
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while ((regs->STATUS.reg & SERCOM_SPI_STATUS_SYNCBUSY) != 0) {
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}
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#else
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#error Unsupported device
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#endif
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}
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static int spi_sam0_configure(struct device *dev,
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const struct spi_config *config)
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{
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const struct spi_sam0_config *cfg = dev->config->config_info;
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SercomSpi *regs = cfg->regs;
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SERCOM_SPI_CTRLA_Type ctrla = {.reg = 0};
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SERCOM_SPI_CTRLB_Type ctrlb = {.reg = 0};
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int div;
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if (SPI_OP_MODE_GET(config->operation) != SPI_OP_MODE_MASTER) {
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/* Slave mode is not implemented. */
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return -ENOTSUP;
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}
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ctrla.bit.MODE = SERCOM_SPI_CTRLA_MODE_SPI_MASTER_Val;
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if ((config->operation & SPI_TRANSFER_LSB) != 0) {
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ctrla.bit.DORD = 1;
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}
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if ((config->operation & SPI_MODE_CPOL) != 0) {
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ctrla.bit.CPOL = 1;
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}
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if ((config->operation & SPI_MODE_CPHA) != 0) {
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ctrla.bit.CPHA = 1;
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}
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ctrla.reg |= cfg->pads;
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if ((config->operation & SPI_MODE_LOOP) != 0) {
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/* Put MISO and MOSI on the same pad */
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ctrla.bit.DOPO = 0;
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ctrla.bit.DIPO = 0;
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}
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ctrla.bit.ENABLE = 1;
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ctrlb.bit.RXEN = 1;
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if (SPI_WORD_SIZE_GET(config->operation) != 8) {
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return -ENOTSUP;
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}
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/* 8 bits per transfer */
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ctrlb.bit.CHSIZE = 0;
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/* Use the requested or next higest possible frequency */
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div = (SOC_ATMEL_SAM0_GCLK0_FREQ_HZ / config->frequency) / 2 - 1;
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div = max(0, min(UINT8_MAX, div));
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/* Update the configuration only if it has changed */
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if (regs->CTRLA.reg != ctrla.reg || regs->CTRLB.reg != ctrlb.reg ||
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regs->BAUD.reg != div) {
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regs->CTRLA.bit.ENABLE = 0;
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wait_synchronization(regs);
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regs->CTRLB = ctrlb;
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wait_synchronization(regs);
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regs->BAUD.reg = div;
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wait_synchronization(regs);
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regs->CTRLA = ctrla;
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wait_synchronization(regs);
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}
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return 0;
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}
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static bool spi_sam0_transfer_ongoing(struct spi_sam0_data *data)
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{
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return spi_context_tx_on(&data->ctx) || spi_context_rx_on(&data->ctx);
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}
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static void spi_sam0_shift_master(SercomSpi *regs, struct spi_sam0_data *data)
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{
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u8_t tx;
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u8_t rx;
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if (spi_context_tx_buf_on(&data->ctx)) {
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tx = *(u8_t *)(data->ctx.tx_buf);
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} else {
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tx = 0;
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}
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while (!regs->INTFLAG.bit.DRE) {
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}
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regs->DATA.reg = tx;
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spi_context_update_tx(&data->ctx, 1, 1);
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while (!regs->INTFLAG.bit.RXC) {
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}
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rx = regs->DATA.reg;
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if (spi_context_rx_buf_on(&data->ctx)) {
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*data->ctx.rx_buf = rx;
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}
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spi_context_update_rx(&data->ctx, 1, 1);
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}
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/* Finish any ongoing writes and drop any remaining read data */
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static void spi_sam0_finish(SercomSpi *regs)
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{
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while (!regs->INTFLAG.bit.TXC) {
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}
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while (regs->INTFLAG.bit.RXC) {
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(void)regs->DATA.reg;
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}
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}
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/* Fast path that transmits a buf */
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static void spi_sam0_fast_tx(SercomSpi *regs, const struct spi_buf *tx_buf)
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{
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const u8_t *p = tx_buf->buf;
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const u8_t *pend = (u8_t *)tx_buf->buf + tx_buf->len;
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u8_t ch;
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while (p != pend) {
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ch = *p++;
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while (!regs->INTFLAG.bit.DRE) {
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}
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regs->DATA.reg = ch;
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}
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spi_sam0_finish(regs);
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}
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/* Fast path that reads into a buf */
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static void spi_sam0_fast_rx(SercomSpi *regs, const struct spi_buf *rx_buf)
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{
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u8_t *rx = rx_buf->buf;
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int len = rx_buf->len;
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if (len <= 0) {
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return;
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}
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/* See the comment in spi_sam0_fast_txrx re: interleaving. */
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/* Write the first byte */
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regs->DATA.reg = 0;
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len--;
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while (len) {
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/* Load byte N+1 into the transmit register */
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regs->DATA.reg = 0;
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len--;
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/* Read byte N+0 from the receive register */
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while (!regs->INTFLAG.bit.RXC) {
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}
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*rx++ = regs->DATA.reg;
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}
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/* Read the final incoming byte */
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while (!regs->INTFLAG.bit.RXC) {
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}
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*rx = regs->DATA.reg;
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spi_sam0_finish(regs);
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}
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/* Fast path that writes and reads bufs of the same length */
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static void spi_sam0_fast_txrx(SercomSpi *regs,
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const struct spi_buf *tx_buf,
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const struct spi_buf *rx_buf)
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{
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const u8_t *tx = tx_buf->buf;
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const u8_t *txend = (u8_t *)tx_buf->buf + tx_buf->len;
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u8_t *rx = rx_buf->buf;
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size_t len = rx_buf->len;
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if (len <= 0) {
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return;
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}
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/*
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* The code below interleaves the transmit writes with the
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* receive reads to keep the bus fully utilised. The code is
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* equivalent to:
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*
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* Transmit byte 0
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* Loop:
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* - Transmit byte n+1
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* - Receive byte n
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* Receive the final byte
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*/
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/* Write the first byte */
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regs->DATA.reg = *tx++;
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while (tx != txend) {
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/* Load byte N+1 into the transmit register. TX is
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* single buffered and we have at most one byte in
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* flight so skip the DRE check.
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*/
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regs->DATA.reg = *tx++;
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/* Read byte N+0 from the receive register */
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while (!regs->INTFLAG.bit.RXC) {
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}
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*rx++ = regs->DATA.reg;
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}
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/* Read the final incoming byte */
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while (!regs->INTFLAG.bit.RXC) {
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}
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*rx = regs->DATA.reg;
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spi_sam0_finish(regs);
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}
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/* Fast path where every overlapping tx and rx buffer is the same length */
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static void spi_sam0_fast_transceive(struct device *dev,
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const struct spi_config *config,
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const struct spi_buf_set *tx_bufs,
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const struct spi_buf_set *rx_bufs)
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{
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const struct spi_sam0_config *cfg = dev->config->config_info;
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size_t tx_count = 0;
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size_t rx_count = 0;
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SercomSpi *regs = cfg->regs;
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const struct spi_buf *tx;
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const struct spi_buf *rx;
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if (tx_bufs) {
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tx = tx_bufs->buffers;
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tx_count = tx_bufs->count;
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}
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if (rx_bufs) {
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rx = rx_bufs->buffers;
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rx_count = rx_bufs->count;
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} else {
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rx = NULL;
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}
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while (tx_count != 0 && rx_count != 0) {
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if (tx->buf == NULL) {
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spi_sam0_fast_rx(regs, rx);
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} else if (rx->buf == NULL) {
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spi_sam0_fast_tx(regs, tx);
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} else {
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spi_sam0_fast_txrx(regs, tx, rx);
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}
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tx++;
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tx_count--;
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rx++;
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rx_count--;
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}
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for (; tx_count != 0; tx_count--) {
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spi_sam0_fast_tx(regs, tx++);
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}
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for (; rx_count != 0; rx_count--) {
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spi_sam0_fast_rx(regs, rx++);
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}
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}
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/* Returns true if the request is suitable for the fast
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* path. Specifically, the bufs are a sequence of:
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*
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* - Zero or more RX and TX buf pairs where each is the same length.
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* - Zero or more trailing RX only bufs
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* - Zero or more trailing TX only bufs
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*/
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static bool spi_sam0_is_regular(const struct spi_buf_set *tx_bufs,
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const struct spi_buf_set *rx_bufs)
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{
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const struct spi_buf *tx = NULL;
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const struct spi_buf *rx = NULL;
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size_t tx_count = 0;
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size_t rx_count = 0;
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if (tx_bufs) {
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tx = tx_bufs->buffers;
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tx_count = tx_bufs->count;
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}
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if (rx_bufs) {
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rx = rx_bufs->buffers;
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rx_count = rx_bufs->count;
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}
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if (!tx || !rx) {
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return false;
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}
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while (tx_count != 0 && rx_count != 0) {
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if (tx->len != rx->len) {
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return false;
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}
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tx++;
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tx_count--;
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rx++;
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rx_count--;
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}
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return true;
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}
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static int spi_sam0_transceive(struct device *dev,
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const struct spi_config *config,
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const struct spi_buf_set *tx_bufs,
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const struct spi_buf_set *rx_bufs)
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{
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const struct spi_sam0_config *cfg = dev->config->config_info;
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struct spi_sam0_data *data = dev->driver_data;
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SercomSpi *regs = cfg->regs;
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int err;
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spi_context_lock(&data->ctx, false, NULL);
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err = spi_sam0_configure(dev, config);
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if (err != 0) {
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goto done;
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}
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data->ctx.config = config;
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spi_context_cs_configure(&data->ctx);
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spi_context_cs_control(&data->ctx, true);
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/* This driver special cases the common send only, receive
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* only, and transmit then receive operations. This special
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* casing is 4x faster than the spi_context() routines
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* and allows the transmit and receive to be interleaved.
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*/
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if (spi_sam0_is_regular(tx_bufs, rx_bufs)) {
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spi_sam0_fast_transceive(dev, config, tx_bufs, rx_bufs);
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} else {
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spi_context_buffers_setup(&data->ctx, tx_bufs, rx_bufs, 1);
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do {
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spi_sam0_shift_master(regs, data);
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} while (spi_sam0_transfer_ongoing(data));
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}
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spi_context_cs_control(&data->ctx, false);
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done:
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spi_context_release(&data->ctx, err);
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return err;
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}
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#ifdef CONFIG_SPI_ASYNC
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static int spi_sam0_transceive_async(struct device *dev,
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const struct spi_config *config,
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const struct spi_buf_set *tx_bufs,
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const struct spi_buf_set *rx_bufs,
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struct k_poll_signal *async)
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{
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return -ENOTSUP;
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}
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#endif /* CONFIG_SPI_ASYNC */
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static int spi_sam0_release(struct device *dev,
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const struct spi_config *config)
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{
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struct spi_sam0_data *data = dev->driver_data;
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spi_context_unlock_unconditionally(&data->ctx);
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return 0;
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}
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static int spi_sam0_init(struct device *dev)
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{
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const struct spi_sam0_config *cfg = dev->config->config_info;
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struct spi_sam0_data *data = dev->driver_data;
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SercomSpi *regs = cfg->regs;
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/* Enable the GCLK */
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GCLK->CLKCTRL.reg = cfg->gclk_clkctrl_id | GCLK_CLKCTRL_GEN_GCLK0 |
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GCLK_CLKCTRL_CLKEN;
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/* Enable SERCOM clock in PM */
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PM->APBCMASK.reg |= cfg->pm_apbcmask;
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/* Disable all SPI interrupts */
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regs->INTENCLR.reg = SERCOM_SPI_INTENCLR_MASK;
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wait_synchronization(regs);
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spi_context_unlock_unconditionally(&data->ctx);
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/* The device will be configured and enabled when transceive
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* is called.
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*/
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return 0;
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}
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static const struct spi_driver_api spi_sam0_driver_api = {
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.transceive = spi_sam0_transceive,
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#ifdef CONFIG_SPI_ASYNC
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.transceive_async = spi_sam0_transceive_async,
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#endif
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.release = spi_sam0_release,
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};
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#define CONFIG_SPI_SAM0_SERCOM_PADS(n) \
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SERCOM_SPI_CTRLA_DIPO(DT_SPI_SAM0_SERCOM##n##_DIPO) | \
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SERCOM_SPI_CTRLA_DOPO(DT_SPI_SAM0_SERCOM##n##_DOPO)
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#define SPI_SAM0_DEFINE_CONFIG(n) \
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static const struct spi_sam0_config spi_sam0_config_##n = { \
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.regs = (SercomSpi *)DT_SPI_SAM0_SERCOM##n##_BASE_ADDRESS, \
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.pm_apbcmask = PM_APBCMASK_SERCOM##n, \
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.gclk_clkctrl_id = GCLK_CLKCTRL_ID_SERCOM##n##_CORE, \
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.pads = CONFIG_SPI_SAM0_SERCOM_PADS(n) \
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}
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#define SPI_SAM0_DEVICE_INIT(n) \
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SPI_SAM0_DEFINE_CONFIG(n); \
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static struct spi_sam0_data spi_sam0_dev_data_##n = { \
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SPI_CONTEXT_INIT_LOCK(spi_sam0_dev_data_##n, ctx), \
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SPI_CONTEXT_INIT_SYNC(spi_sam0_dev_data_##n, ctx), \
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}; \
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DEVICE_AND_API_INIT(spi_sam0_##n, \
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DT_SPI_SAM0_SERCOM##n##_LABEL, \
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&spi_sam0_init, &spi_sam0_dev_data_##n, \
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&spi_sam0_config_##n, POST_KERNEL, \
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CONFIG_SPI_INIT_PRIORITY, &spi_sam0_driver_api)
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#if DT_SPI_SAM0_SERCOM0_BASE_ADDRESS
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SPI_SAM0_DEVICE_INIT(0);
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#endif
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#if DT_SPI_SAM0_SERCOM1_BASE_ADDRESS
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SPI_SAM0_DEVICE_INIT(1);
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#endif
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#if DT_SPI_SAM0_SERCOM2_BASE_ADDRESS
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SPI_SAM0_DEVICE_INIT(2);
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#endif
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#if DT_SPI_SAM0_SERCOM3_BASE_ADDRESS
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SPI_SAM0_DEVICE_INIT(3);
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#endif
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#if DT_SPI_SAM0_SERCOM4_BASE_ADDRESS
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SPI_SAM0_DEVICE_INIT(4);
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#endif
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#if DT_SPI_SAM0_SERCOM5_BASE_ADDRESS
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SPI_SAM0_DEVICE_INIT(5);
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#endif
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