291 lines
8.4 KiB
C
291 lines
8.4 KiB
C
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/**
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* \file
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*
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* \brief SAM Serial Peripheral Interface Driver
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*
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* Copyright (C) 2012-2016 Atmel Corporation. All rights reserved.
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*
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* \asf_license_start
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*
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* \page License
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* 3. The name of Atmel may not be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* 4. This software may only be redistributed and used in connection with an
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* Atmel microcontroller product.
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*
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* THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
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* EXPRESSLY AND SPECIFICALLY DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR
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* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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* \asf_license_stop
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*
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*/
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/*
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* Support and FAQ: visit <a href="http://www.atmel.com/design-support/">Atmel Support</a>
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*/
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#include "sercom.h"
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#define SHIFT 32
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#define BAUD_INT_MAX 8192
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#define BAUD_FP_MAX 8
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#if !defined(__DOXYGEN__)
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/**
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* \internal Configuration structure to save current gclk status.
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*/
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struct _sercom_conf {
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/* Status of gclk generator initialization */
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bool generator_is_set;
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/* Sercom gclk generator used */
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enum gclk_generator generator_source;
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};
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static struct _sercom_conf _sercom_config;
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/**
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* \internal Calculate 64 bit division, ref can be found in
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* http://en.wikipedia.org/wiki/Division_algorithm#Long_division
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*/
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static uint64_t long_division(uint64_t n, uint64_t d)
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{
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int32_t i;
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uint64_t q = 0, r = 0, bit_shift;
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for (i = 63; i >= 0; i--) {
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bit_shift = (uint64_t)1 << i;
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r = r << 1;
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if (n & bit_shift) {
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r |= 0x01;
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}
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if (r >= d) {
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r = r - d;
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q |= bit_shift;
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}
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}
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return q;
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}
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/**
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* \internal Calculate synchronous baudrate value (SPI/UART)
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*/
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enum status_code _sercom_get_sync_baud_val(
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const uint32_t baudrate,
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const uint32_t external_clock,
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uint16_t *const baudvalue)
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{
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/* Baud value variable */
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uint16_t baud_calculated = 0;
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uint32_t clock_value = external_clock;
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/* Check if baudrate is outside of valid range */
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if (baudrate > (external_clock / 2)) {
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/* Return with error code */
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return STATUS_ERR_BAUDRATE_UNAVAILABLE;
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}
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/* Calculate BAUD value from clock frequency and baudrate */
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clock_value = external_clock / 2;
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while (clock_value >= baudrate) {
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clock_value = clock_value - baudrate;
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baud_calculated++;
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}
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baud_calculated = baud_calculated - 1;
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/* Check if BAUD value is more than 255, which is maximum
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* for synchronous mode */
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if (baud_calculated > 0xFF) {
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/* Return with an error code */
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return STATUS_ERR_BAUDRATE_UNAVAILABLE;
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} else {
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*baudvalue = baud_calculated;
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return STATUS_OK;
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}
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}
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/**
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* \internal Calculate asynchronous baudrate value (UART)
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*/
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enum status_code _sercom_get_async_baud_val(
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const uint32_t baudrate,
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const uint32_t peripheral_clock,
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uint16_t *const baudval,
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enum sercom_asynchronous_operation_mode mode,
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enum sercom_asynchronous_sample_num sample_num)
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{
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/* Temporary variables */
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uint64_t ratio = 0;
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uint64_t scale = 0;
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uint64_t baud_calculated = 0;
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uint8_t baud_fp;
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uint32_t baud_int = 0;
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uint64_t temp1;
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/* Check if the baudrate is outside of valid range */
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if ((baudrate * sample_num) > peripheral_clock) {
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/* Return with error code */
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return STATUS_ERR_BAUDRATE_UNAVAILABLE;
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}
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if(mode == SERCOM_ASYNC_OPERATION_MODE_ARITHMETIC) {
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/* Calculate the BAUD value */
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temp1 = ((sample_num * (uint64_t)baudrate) << SHIFT);
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ratio = long_division(temp1, peripheral_clock);
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scale = ((uint64_t)1 << SHIFT) - ratio;
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baud_calculated = (65536 * scale) >> SHIFT;
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} else if(mode == SERCOM_ASYNC_OPERATION_MODE_FRACTIONAL) {
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temp1 = ((uint64_t)baudrate * sample_num);
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baud_int = long_division( peripheral_clock, temp1);
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if(baud_int > BAUD_INT_MAX) {
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return STATUS_ERR_BAUDRATE_UNAVAILABLE;
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}
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temp1 = long_division( 8 * (uint64_t)peripheral_clock, temp1);
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baud_fp = temp1 - 8 * baud_int;
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baud_calculated = baud_int | (baud_fp << 13);
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}
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*baudval = baud_calculated;
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return STATUS_OK;
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}
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#endif
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/**
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* \brief Set GCLK channel to generator.
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*
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* This will set the appropriate GCLK channel to the requested GCLK generator.
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* This will set the generator for all SERCOM instances, and the user will thus
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* only be able to set the same generator that has previously been set, if any.
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*
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* After the generator has been set the first time, the generator can be changed
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* using the \c force_change flag.
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*
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* \param[in] generator_source The generator to use for SERCOM.
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* \param[in] force_change Force change the generator.
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*
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* \return Status code indicating the GCLK generator change operation.
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* \retval STATUS_OK If the generator update request was
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* successful.
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* \retval STATUS_ERR_ALREADY_INITIALIZED If a generator was already configured
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* and the new configuration was not
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* forced.
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*/
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enum status_code sercom_set_gclk_generator(
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const enum gclk_generator generator_source,
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const bool force_change)
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{
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/* Check if valid option */
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if (!_sercom_config.generator_is_set || force_change) {
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/* Create and fill a GCLK configuration structure for the new config */
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struct system_gclk_chan_config gclk_chan_conf;
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system_gclk_chan_get_config_defaults(&gclk_chan_conf);
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gclk_chan_conf.source_generator = generator_source;
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system_gclk_chan_set_config(SERCOM_GCLK_ID, &gclk_chan_conf);
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system_gclk_chan_enable(SERCOM_GCLK_ID);
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/* Save config */
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_sercom_config.generator_source = generator_source;
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_sercom_config.generator_is_set = true;
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return STATUS_OK;
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} else if (generator_source == _sercom_config.generator_source) {
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/* Return status OK if same config */
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return STATUS_OK;
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}
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/* Return invalid config to already initialized GCLK */
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return STATUS_ERR_ALREADY_INITIALIZED;
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}
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/** \internal
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* Creates a switch statement case entry to convert a SERCOM instance and pad
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* index to the default SERCOM pad MUX setting.
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*/
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#define _SERCOM_PAD_DEFAULTS_CASE(n, pad) \
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case (uintptr_t)SERCOM##n: \
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switch (pad) { \
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case 0: \
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return SERCOM##n##_PAD0_DEFAULT; \
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case 1: \
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return SERCOM##n##_PAD1_DEFAULT; \
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case 2: \
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return SERCOM##n##_PAD2_DEFAULT; \
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case 3: \
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return SERCOM##n##_PAD3_DEFAULT; \
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} \
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break;
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/**
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* \internal Gets the default PAD pinout for a given SERCOM.
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*
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* Returns the pinmux settings for the given SERCOM and pad. This is used
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* for default configuration of pins.
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*
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* \param[in] sercom_module Pointer to the SERCOM module
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* \param[in] pad PAD to get default pinout for
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*
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* \returns The default pinmux for the given SERCOM instance and PAD
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*
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*/
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uint32_t _sercom_get_default_pad(
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Sercom *const sercom_module,
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const uint8_t pad)
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{
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switch ((uintptr_t)sercom_module) {
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/* Auto-generate a lookup table for the default SERCOM pad defaults */
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MREPEAT(SERCOM_INST_NUM, _SERCOM_PAD_DEFAULTS_CASE, pad)
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}
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Assert(false);
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return 0;
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}
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/**
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* \internal
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* Find index of given instance.
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*
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* \param[in] sercom_instance Instance pointer.
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*
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* \return Index of given instance.
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*/
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uint8_t _sercom_get_sercom_inst_index(
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Sercom *const sercom_instance)
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{
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/* Save all available SERCOM instances for compare */
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Sercom *sercom_instances[SERCOM_INST_NUM] = SERCOM_INSTS;
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/* Find index for sercom instance */
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for (uint32_t i = 0; i < SERCOM_INST_NUM; i++) {
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if ((uintptr_t)sercom_instance == (uintptr_t)sercom_instances[i]) {
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return i;
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}
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}
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/* Invalid data given */
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Assert(false);
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return 0;
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}
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