320 lines
11 KiB
C
320 lines
11 KiB
C
/****************************************************************************
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* arch/arm/src/sam34/sam_freerun.c
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*
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* Copyright (C) 2015 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* References:
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*
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* Atmel NoOS sample code.
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*
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* The Atmel sample code has a BSD compatible license that requires this
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* copyright notice:
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*
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* Copyright (c) 2011, Atmel Corporation
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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
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the names NuttX nor Atmel nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* 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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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sys/types.h>
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#include <stdint.h>
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#include <stdbool.h>
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#include <assert.h>
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#include <errno.h>
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#include <nuttx/irq.h>
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#include <nuttx/clock.h>
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#include "sam4cm_freerun.h"
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#ifdef CONFIG_SAM34_FREERUN
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: sam_freerun_handler
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*
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* Description:
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* Timer interrupt callback. When the freerun timer counter overflows,
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* this interrupt will occur. We will just increment an overflow count.
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*
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* Input Parameters:
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* tch - The handle that represents the timer state
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* arg - An opaque argument provided when the interrupt was registered
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* sr - The value of the timer interrupt status register at the time
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* that the interrupt occurred.
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*
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* Returned Value:
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* None
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*
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****************************************************************************/
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static void sam_freerun_handler(TC_HANDLE tch, void *arg, uint32_t sr)
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{
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struct sam_freerun_s *freerun = (struct sam_freerun_s *)arg;
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DEBUGASSERT(freerun && freerun->overflow < UINT32_MAX);
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freerun->overflow++;
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: sam_freerun_initialize
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*
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* Description:
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* Initialize the freerun timer wrapper
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*
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* Input Parameters:
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* freerun Caller allocated instance of the freerun state structure
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* chan Timer counter channel to be used. See the TC_CHAN*
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* definitions in arch/arm/src/sam34/sam_tc.h.
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* resolution The required resolution of the timer in units of
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* microseconds. NOTE that the range is restricted to the
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* range of uint16_t (excluding zero).
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*
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* Returned Value:
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* Zero (OK) is returned on success; a negated errno value is returned
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* on failure.
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*
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****************************************************************************/
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int sam_freerun_initialize(struct sam_freerun_s *freerun, int chan,
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uint16_t resolution)
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{
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uint32_t frequency;
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uint32_t divisor;
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uint32_t cmr;
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int ret;
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tmrinfo("chan=%d resolution=%d usec\n", chan, resolution);
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DEBUGASSERT(freerun && resolution > 0);
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/* Get the TC frequency the corresponds to the requested resolution */
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frequency = USEC_PER_SEC / (uint32_t)resolution;
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/* The pre-calculate values to use when we start the timer */
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ret = sam_tc_divisor(frequency, &divisor, &cmr);
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if (ret < 0)
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{
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tmrerr("ERROR: sam_tc_divisor failed: %d\n", ret);
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return ret;
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}
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tmrinfo("frequency=%lu, divisor=%u, cmr=%08lx\n",
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(unsigned long)frequency, (unsigned long)divisor,
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(unsigned long)cmr);
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/* Allocate the timer/counter and select its mode of operation
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*
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* CMR_TCCLKS - Returned by sam_tc_divisor
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* TC_CMR_CLKI=0 - Not inverted
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* TC_CMR_BURST_NONE - Not gated by an external signal
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* TC_CMR_CPCSTOP=0 - Don't stop the clock on an RC compare event
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* TC_CMR_CPCDIS=0 - Don't disable the clock on an RC compare event
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* TC_CMR_EEVTEDG_NONE - No external events (and, hence, no edges
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* TC_CMR_EEVT_TIOB - ???? REVISIT
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* TC_CMR_ENET=0 - External event trigger disabled
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* TC_CMR_WAVSEL_UP - TC_CV is incremented from 0 to 0xffffffff
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* TC_CMR_WAVE - Waveform mode
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* TC_CMR_ACPA_NONE - RA compare has no effect on TIOA
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* TC_CMR_ACPC_NONE - RC compare has no effect on TIOA
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* TC_CMR_AEEVT_NONE - No external event effect on TIOA
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* TC_CMR_ASWTRG_NONE - No software trigger effect on TIOA
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* TC_CMR_BCPB_NONE - RB compare has no effect on TIOB
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* TC_CMR_BCPC_NONE - RC compare has no effect on TIOB
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* TC_CMR_BEEVT_NONE - No external event effect on TIOB
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* TC_CMR_BSWTRG_NONE - No software trigger effect on TIOB
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*/
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cmr |= (TC_CMR_BURST_NOTGATED | TC_CMR_EEVTEDG_NONE | TC_CMR_EEVT_TIOB |
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TC_CMR_WAVSEL_UP | TC_CMR_WAVE | TC_CMR_ACPA_NONE |
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TC_CMR_ACPC_NONE | TC_CMR_AEEVT_NONE | TC_CMR_ASWTRG_NONE |
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TC_CMR_BCPB_NONE | TC_CMR_BCPC_NONE | TC_CMR_BEEVT_NONE |
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TC_CMR_BSWTRG_NONE);
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freerun->tch = sam_tc_allocate(chan, cmr);
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if (!freerun->tch)
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{
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tmrerr("ERROR: Failed to allocate timer channel %d\n", chan);
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return -EBUSY;
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}
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/* Initialize the remaining fields in the state structure and return
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* success.
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*/
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freerun->chan = chan;
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freerun->running = false;
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freerun->overflow = 0;
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/* Set up to receive the callback when the counter overflow occurs */
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(void)sam_tc_attach(freerun->tch, sam_freerun_handler, freerun,
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TC_INT_COVFS);
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/* Start the counter */
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sam_tc_start(freerun->tch);
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return OK;
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}
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/****************************************************************************
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* Name: sam_freerun_counter
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*
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* Description:
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* Read the counter register of the free-running timer.
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*
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* Input Parameters:
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* freerun Caller allocated instance of the freerun state structure. This
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* structure must have been previously initialized via a call to
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* sam_freerun_initialize();
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* ts The location in which to return the time from the free-running
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* timer.
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*
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* Returned Value:
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* Zero (OK) is returned on success; a negated errno value is returned
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* on failure.
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*
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****************************************************************************/
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int sam_freerun_counter(struct sam_freerun_s *freerun, struct timespec *ts)
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{
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uint64_t usec;
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uint32_t counter;
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uint32_t verify;
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uint32_t sr;
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uint32_t overflow;
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uint32_t sec;
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irqstate_t flags;
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DEBUGASSERT(freerun && freerun->tch && ts);
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/* Temporarily disable the overflow counter. NOTE that we have to be careful
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* here because sam_tc_getpending() will reset the pending interrupt status.
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* If we do not handle the overflow here then, it will be lost.
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*/
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flags = enter_critical_section();
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overflow = freerun->overflow;
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counter = sam_tc_getcounter(freerun->tch);
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sr = sam_tc_getpending(freerun->tch);
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verify = sam_tc_getcounter(freerun->tch);
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/* If an interrupt was pending before we re-enabled interrupts,
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* then the overflow needs to be incremented.
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*/
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if ((sr & TC_INT_COVFS) != 0)
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{
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/* Increment the overflow count and use the value of the
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* guaranteed to be AFTER the overflow occurred.
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*/
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overflow++;
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counter = verify;
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/* Update freerun overflow counter. */
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freerun->overflow = overflow;
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}
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leave_critical_section(flags);
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tmrinfo("counter=%lu (%lu) overflow=%lu, sr=%08lx\n",
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(unsigned long)counter, (unsigned long)verify,
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(unsigned long)overflow, (unsigned long)sr);
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/* Convert the whole thing to units of microseconds.
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*
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* frequency = ticks / second
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* seconds = ticks * frequency
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* usecs = (ticks * USEC_PER_SEC) / frequency;
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*/
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usec = ((((uint64_t)overflow << 16) + (uint64_t)counter) * USEC_PER_SEC) /
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sam_tc_divfreq(freerun->tch);
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/* And return the value of the timer */
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sec = (uint32_t)(usec / USEC_PER_SEC);
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ts->tv_sec = sec;
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ts->tv_nsec = (usec - (sec * USEC_PER_SEC)) * NSEC_PER_USEC;
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tmrinfo("usec=%llu ts=(%lu, %lu)\n",
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usec, (unsigned long)ts->tv_sec, (unsigned long)ts->tv_nsec);
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return OK;
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}
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/****************************************************************************
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* Name: sam_freerun_uninitialize
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*
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* Description:
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* Stop the free-running timer and release all resources that it uses.
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*
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* Input Parameters:
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* freerun Caller allocated instance of the freerun state structure. This
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* structure must have been previously initialized via a call to
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* sam_freerun_initialize();
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*
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* Returned Value:
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* Zero (OK) is returned on success; a negated errno value is returned
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* on failure.
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*
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****************************************************************************/
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int sam_freerun_uninitialize(struct sam_freerun_s *freerun)
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{
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DEBUGASSERT(freerun && freerun->tch);
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/* Now we can disable the timer interrupt and disable the timer. */
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sam_tc_attach(freerun->tch, NULL, NULL, 0);
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sam_tc_stop(freerun->tch);
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/* Free the timer */
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sam_tc_free(freerun->tch);
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freerun->tch = NULL;
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return OK;
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}
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#endif /* CONFIG_SAM34_FREERUN */
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