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Diffstat (limited to 'bsps/arm/atsam/contrib/libraries/libchip/source/tc.c')
| -rw-r--r-- | bsps/arm/atsam/contrib/libraries/libchip/source/tc.c | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/bsps/arm/atsam/contrib/libraries/libchip/source/tc.c b/bsps/arm/atsam/contrib/libraries/libchip/source/tc.c new file mode 100644 index 0000000000..4ef9bd9f50 --- /dev/null +++ b/bsps/arm/atsam/contrib/libraries/libchip/source/tc.c @@ -0,0 +1,213 @@ +/* ---------------------------------------------------------------------------- */ +/* Atmel Microcontroller Software Support */ +/* SAM Software Package License */ +/* ---------------------------------------------------------------------------- */ +/* Copyright (c) 2015, Atmel Corporation */ +/* */ +/* All rights reserved. */ +/* */ +/* Redistribution and use in source and binary forms, with or without */ +/* modification, are permitted provided that the following condition is met: */ +/* */ +/* - Redistributions of source code must retain the above copyright notice, */ +/* this list of conditions and the disclaimer below. */ +/* */ +/* Atmel's name may not be used to endorse or promote products derived from */ +/* this software without specific prior written permission. */ +/* */ +/* DISCLAIMER: 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 */ +/* 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. */ +/* ---------------------------------------------------------------------------- */ + +/** \addtogroup tc_module + * The TC driver provides the Interface to configure the Timer Counter (TC). + * + * \section Usage + * <ul> + * <li> Optionally, use TC_FindMckDivisor() to let the program find the best + * TCCLKS field value automatically.</li> + * <li> Configure a Timer Counter in the desired mode using TC_Configure().</li> + * <li> Start or stop the timer clock using TC_Start() and TC_Stop().</li> + * + * </ul> + * For more accurate information, please look at the TC section of the Datasheet. + * + * Related files :\n + * \ref tc.c\n + * \ref tc.h.\n +*/ + +/** +* \file +* +* \section Purpose +* +* Interface for configuring and using Timer Counter (TC) peripherals. +* +* \section Usage +* -# Optionally, use TC_FindMckDivisor() to let the program find the best +* TCCLKS field value automatically. +* -# Configure a Timer Counter in the desired mode using TC_Configure(). +* -# Start or stop the timer clock using TC_Start() and TC_Stop(). +*/ + +/** + * \file + * + * Implementation of Timer Counter (TC). + * + */ + +/*------------------------------------------------------------------------------ + * Headers + *-----------------------------------------------------------------------------*/ + +#ifndef __rtems__ +#include "board.h" +#else /* __rtems__ */ +#include <chip.h> +#endif /* __rtems__ */ + +#include <assert.h> + +/*------------------------------------------------------------------------------ + * Global functions + *----------------------------------------------------------------------------*/ + +/** + * \brief Configures a Timer Counter Channel + * + * Configures a Timer Counter to operate in the given mode. Timer is stopped + * after configuration and must be restarted with TC_Start(). All the + * interrupts of the timer are also disabled. + * + * \param pTc Pointer to a Tc instance. + * \param channel Channel number. + * \param mode Operating mode (TC_CMR value). + */ +extern void TC_Configure(Tc *pTc, uint32_t dwChannel, uint32_t dwMode) +{ + TcChannel *pTcCh; + + assert(dwChannel < (sizeof(pTc->TC_CHANNEL) / sizeof( + pTc->TC_CHANNEL[0]))); + pTcCh = pTc->TC_CHANNEL + dwChannel; + + /* Disable TC clock */ + pTcCh->TC_CCR = TC_CCR_CLKDIS; + + /* Disable interrupts */ + pTcCh->TC_IDR = 0xFFFFFFFF; + + /* Clear status register */ + pTcCh->TC_SR; + + /* Set mode */ + pTcCh->TC_CMR = dwMode; +} + +/** + * \brief Reset and Start the TC Channel + * + * Enables the timer clock and performs a software reset to start the counting. + * + * \param pTc Pointer to a Tc instance. + * \param dwChannel Channel number. + */ +extern void TC_Start(Tc *pTc, uint32_t dwChannel) +{ + TcChannel *pTcCh; + + assert(dwChannel < (sizeof(pTc->TC_CHANNEL) / sizeof( + pTc->TC_CHANNEL[0]))); + + pTcCh = pTc->TC_CHANNEL + dwChannel; + pTcCh->TC_CCR = TC_CCR_CLKEN | TC_CCR_SWTRG; +} + +/** + * \brief Stop TC Channel + * + * Disables the timer clock, stopping the counting. + * + * \param pTc Pointer to a Tc instance. + * \param dwChannel Channel number. + */ +extern void TC_Stop(Tc *pTc, uint32_t dwChannel) +{ + TcChannel *pTcCh; + + assert(dwChannel < (sizeof(pTc->TC_CHANNEL) / sizeof( + pTc->TC_CHANNEL[0]))); + + pTcCh = pTc->TC_CHANNEL + dwChannel; + pTcCh->TC_CCR = TC_CCR_CLKDIS; +} + +/** + * \brief Find best MCK divisor + * + * Finds the best MCK divisor given the timer frequency and MCK. The result + * is guaranteed to satisfy the following equation: + * \code + * (MCK / (DIV * 65536)) <= freq <= (MCK / DIV) + * \endcode + * with DIV being the highest possible value. + * + * \param dwFreq Desired timer frequency. + * \param dwMCk Master clock frequency. + * \param dwDiv Divisor value. + * \param dwTcClks TCCLKS field value for divisor. + * \param dwBoardMCK Board clock frequency. + * + * \return 1 if a proper divisor has been found, otherwise 0. + */ +extern uint32_t TC_FindMckDivisor(uint32_t dwFreq, uint32_t dwMCk, + uint32_t *dwDiv, uint32_t *dwTcClks, uint32_t dwBoardMCK) +{ + /* + TCCLKS: + 0 - PCK6: default source - Slow Clock; update according to actual case + 4 - SLCK: (slow clock) is either "Embedded 32kHz RC Oscillator" or + "32768Hz Crystal Oscillator" + */ + const uint32_t adwDivisors[5] = { BOARD_MCK / 32768, 8, 32, 128, BOARD_MCK / 32768 }; + + uint32_t dwIndex = 0; + dwBoardMCK = dwBoardMCK; + + /* Satisfy lower bound */ + while (dwFreq < ((dwMCk / adwDivisors[dwIndex]) / 65536)) { + dwIndex++; + + /* If no divisor can be found, return 0 */ + if (dwIndex == (sizeof(adwDivisors) / sizeof(adwDivisors[0]))) + return 0; + } + + /* Try to maximize DIV while satisfying upper bound */ + while (dwIndex < 4) { + if (dwFreq > (dwMCk / adwDivisors[dwIndex + 1])) + break; + + dwIndex++; + } + + /* Store results */ + if (dwDiv) + *dwDiv = adwDivisors[dwIndex]; + + if (dwTcClks) + *dwTcClks = dwIndex; + + return 1; +} + |