/**
* \file
*
* \brief SAM Serial Peripheral Interface Driver
*
* Copyright (C) 2012-2015 Atmel Corporation. All rights reserved.
*
* \asf_license_start
*
* \page License
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* 3. The name of Atmel may not be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* 4. This software may only be redistributed and used in connection with an
* Atmel microcontroller product.
*
* THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
* EXPRESSLY AND SPECIFICALLY DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* \asf_license_stop
*
*/
/*
* Support and FAQ: visit <a href="http://www.atmel.com/design-support/">Atmel Support</a>
*/
#include "sercom.h"
#define SHIFT 32
#define BAUD_INT_MAX 8192
#define BAUD_FP_MAX 8
#if !defined(__DOXYGEN__)
/**
* \internal Configuration structure to save current gclk status.
*/
struct _sercom_conf {
/* Status of gclk generator initialization. */
bool generator_is_set;
/* Sercom gclk generator used. */
enum gclk_generator generator_source;
};
static struct _sercom_conf _sercom_config;
/**
* \internal Calculate 64 bit division, ref can be found in
* http://en.wikipedia.org/wiki/Division_algorithm#Long_division
*/
static uint64_t long_division(uint64_t n, uint64_t d)
{
int32_t i;
uint64_t q = 0, r = 0, bit_shift;
for (i = 63; i >= 0; i--) {
bit_shift = (uint64_t)1 << i;
r = r << 1;
if (n & bit_shift) {
r |= 0x01;
}
if (r >= d) {
r = r - d;
q |= bit_shift;
}
}
return q;
}
/**
* \internal Calculate synchronous baudrate value (SPI/UART)
*/
enum status_code _sercom_get_sync_baud_val(
const uint32_t baudrate,
const uint32_t external_clock,
uint16_t *const baudvalue)
{
/* Baud value variable */
uint16_t baud_calculated = 0;
uint32_t clock_value = external_clock;
/* Check if baudrate is outside of valid range. */
if (baudrate > (external_clock / 2)) {
/* Return with error code */
return STATUS_ERR_BAUDRATE_UNAVAILABLE;
}
/* Calculate BAUD value from clock frequency and baudrate */
clock_value = external_clock / 2;
while (clock_value >= baudrate) {
clock_value = clock_value - baudrate;
baud_calculated++;
}
baud_calculated = baud_calculated - 1;
/* Check if BAUD value is more than 255, which is maximum
* for synchronous mode */
if (baud_calculated > 0xFF) {
/* Return with an error code */
return STATUS_ERR_BAUDRATE_UNAVAILABLE;
} else {
*baudvalue = baud_calculated;
return STATUS_OK;
}
}
/**
* \internal Calculate asynchronous baudrate value (UART)
*/
enum status_code _sercom_get_async_baud_val(
const uint32_t baudrate,
const uint32_t peripheral_clock,
uint16_t *const baudval,
enum sercom_asynchronous_operation_mode mode,
enum sercom_asynchronous_sample_num sample_num)
{
/* Temporary variables */
uint64_t ratio = 0;
uint64_t scale = 0;
uint64_t baud_calculated = 0;
uint8_t baud_fp;
uint32_t baud_int = 0;
uint64_t temp1, temp2;
/* Check if the baudrate is outside of valid range */
if ((baudrate * sample_num) > peripheral_clock) {
/* Return with error code */
return STATUS_ERR_BAUDRATE_UNAVAILABLE;
}
if(mode == SERCOM_ASYNC_OPERATION_MODE_ARITHMETIC) {
/* Calculate the BAUD value */
temp1 = ((sample_num * (uint64_t)baudrate) << SHIFT);
ratio = long_division(temp1, peripheral_clock);
scale = ((uint64_t)1 << SHIFT) - ratio;
baud_calculated = (65536 * scale) >> SHIFT;
} else if(mode == SERCOM_ASYNC_OPERATION_MODE_FRACTIONAL) {
for(baud_fp = 0; baud_fp < BAUD_FP_MAX; baud_fp++) {
temp1 = BAUD_FP_MAX * (uint64_t)peripheral_clock;
temp2 = ((uint64_t)baudrate * sample_num);
baud_int = long_division(temp1, temp2);
baud_int -= baud_fp;
baud_int = baud_int / BAUD_FP_MAX;
if(baud_int < BAUD_INT_MAX) {
break;
}
}
if(baud_fp == BAUD_FP_MAX) {
return STATUS_ERR_BAUDRATE_UNAVAILABLE;
}
baud_calculated = baud_int | (baud_fp << 13);
}
*baudval = baud_calculated;
return STATUS_OK;
}
#endif
/**
* \brief Set GCLK channel to generator.
*
* This will set the appropriate GCLK channel to the requested GCLK generator.
* This will set the generator for all SERCOM instances, and the user will thus
* only be able to set the same generator that has previously been set, if any.
*
* After the generator has been set the first time, the generator can be changed
* using the \c force_change flag.
*
* \param[in] generator_source The generator to use for SERCOM.
* \param[in] force_change Force change the generator.
*
* \return Status code indicating the GCLK generator change operation.
* \retval STATUS_OK If the generator update request was
* successful.
* \retval STATUS_ERR_ALREADY_INITIALIZED If a generator was already configured
* and the new configuration was not
* forced.
*/
enum status_code sercom_set_gclk_generator(
const enum gclk_generator generator_source,
const bool force_change)
{
/* Check if valid option. */
if (!_sercom_config.generator_is_set || force_change) {
/* Create and fill a GCLK configuration structure for the new config. */
struct system_gclk_chan_config gclk_chan_conf;
system_gclk_chan_get_config_defaults(&gclk_chan_conf);
gclk_chan_conf.source_generator = generator_source;
system_gclk_chan_set_config(SERCOM_GCLK_ID, &gclk_chan_conf);
system_gclk_chan_enable(SERCOM_GCLK_ID);
/* Save config. */
_sercom_config.generator_source = generator_source;
_sercom_config.generator_is_set = true;
return STATUS_OK;
} else if (generator_source == _sercom_config.generator_source) {
/* Return status OK if same config. */
return STATUS_OK;
}
/* Return invalid config to already initialized GCLK. */
return STATUS_ERR_ALREADY_INITIALIZED;
}
/** \internal
* Creates a switch statement case entry to convert a SERCOM instance and pad
* index to the default SERCOM pad MUX setting.
*/
#define _SERCOM_PAD_DEFAULTS_CASE(n, pad) \
case (uintptr_t)SERCOM##n: \
switch (pad) { \
case 0: \
return SERCOM##n##_PAD0_DEFAULT; \
case 1: \
return SERCOM##n##_PAD1_DEFAULT; \
case 2: \
return SERCOM##n##_PAD2_DEFAULT; \
case 3: \
return SERCOM##n##_PAD3_DEFAULT; \
} \
break;
/**
* \internal Gets the default PAD pinout for a given SERCOM.
*
* Returns the pinmux settings for the given SERCOM and pad. This is used
* for default configuration of pins.
*
* \param[in] sercom_module Pointer to the SERCOM module
* \param[in] pad PAD to get default pinout for
*
* \returns The default pinmux for the given SERCOM instance and PAD
*
*/
uint32_t _sercom_get_default_pad(
Sercom *const sercom_module,
const uint8_t pad)
{
switch ((uintptr_t)sercom_module) {
/* Auto-generate a lookup table for the default SERCOM pad defaults */
MREPEAT(SERCOM_INST_NUM, _SERCOM_PAD_DEFAULTS_CASE, pad)
}
Assert(false);
return 0;
}
/**
* \internal
* Find index of given instance.
*
* \param[in] sercom_instance Instance pointer.
*
* \return Index of given instance.
*/
uint8_t _sercom_get_sercom_inst_index(
Sercom *const sercom_instance)
{
/* Save all available SERCOM instances for compare. */
Sercom *sercom_instances[SERCOM_INST_NUM] = SERCOM_INSTS;
/* Find index for sercom instance. */
for (uint32_t i = 0; i < SERCOM_INST_NUM; i++) {
if ((uintptr_t)sercom_instance == (uintptr_t)sercom_instances[i]) {
return i;
}
}
/* Invalid data given. */
Assert(false);
return 0;
}
