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gerrit.osmocom.org / simtrace2 / acae412b2a67b3eaf10e222c7304a553b6741377 / . / firmware / src_sam3s / tc.c
blob: 9cad54670d0690a8f3898bc98f0d8b986a9e484e [file] [log] [blame]
Christina Quast8be71e42014-12-02 13:06:01 +0100[diff] [blame]1/* ----------------------------------------------------------------------------
2 * ATMEL Microcontroller Software Support
3 * ----------------------------------------------------------------------------
4 * Copyright (c) 2009, Atmel Corporation
5 *
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions are met:
10 *
11 * - Redistributions of source code must retain the above copyright notice,
12 * this list of conditions and the disclaimer below.
13 *
14 * Atmel's name may not be used to endorse or promote products derived from
15 * this software without specific prior written permission.
16 *
17 * DISCLAIMER: THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
19 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
20 * DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
23 * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
24 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
25 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
26 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 * ----------------------------------------------------------------------------
28 */
29
30/**
31 * \file
32 *
33 * Implementation of Timer Counter (TC).
34 *
35 */
36
37/*------------------------------------------------------------------------------
38 * Headers
39 *------------------------------------------------------------------------------*/
40
41#include "chip.h"
42
43#include <assert.h>
44
45/*------------------------------------------------------------------------------
46 * Global functions
47 *------------------------------------------------------------------------------*/
48
49/**
50 * \brief Configures a Timer Counter Channel
51 *
52 * Configures a Timer Counter to operate in the given mode. Timer is stopped
53 * after configuration and must be restarted with TC_Start(). All the
54 * interrupts of the timer are also disabled.
55 *
56 * \param pTc Pointer to a Tc instance.
57 * \param channel Channel number.
58 * \param mode Operating mode (TC_CMR value).
59 */
60extern void TC_Configure( Tc *pTc, uint32_t dwChannel, uint32_t dwMode )
61{
62 TcChannel* pTcCh ;
63
64 assert( dwChannel < (sizeof( pTc->TC_CHANNEL )/sizeof( pTc->TC_CHANNEL[0] )) ) ;
65 pTcCh = pTc->TC_CHANNEL+dwChannel ;
66
67 /* Disable TC clock */
68 pTcCh->TC_CCR = TC_CCR_CLKDIS ;
69
70 /* Disable interrupts */
71 pTcCh->TC_IDR = 0xFFFFFFFF ;
72
73 /* Clear status register */
74 pTcCh->TC_SR ;
75
76 /* Set mode */
77 pTcCh->TC_CMR = dwMode ;
78}
79
80/**
81 * \brief Reset and Start the TC Channel
82 *
83 * Enables the timer clock and performs a software reset to start the counting.
84 *
85 * \param pTc Pointer to a Tc instance.
86 * \param dwChannel Channel number.
87 */
88extern void TC_Start( Tc *pTc, uint32_t dwChannel )
89{
90 TcChannel* pTcCh ;
91
92 assert( dwChannel < (sizeof( pTc->TC_CHANNEL )/sizeof( pTc->TC_CHANNEL[0] )) ) ;
93
94 pTcCh = pTc->TC_CHANNEL+dwChannel ;
95 pTcCh->TC_CCR = TC_CCR_CLKEN | TC_CCR_SWTRG ;
96}
97
98/**
99 * \brief Stop TC Channel
100 *
101 * Disables the timer clock, stopping the counting.
102 *
103 * \param pTc Pointer to a Tc instance.
104 * \param dwChannel Channel number.
105 */
106extern void TC_Stop(Tc *pTc, uint32_t dwChannel )
107{
108 TcChannel* pTcCh ;
109
110 assert( dwChannel < (sizeof( pTc->TC_CHANNEL )/sizeof( pTc->TC_CHANNEL[0] )) ) ;
111
112 pTcCh = pTc->TC_CHANNEL+dwChannel ;
113 pTcCh->TC_CCR = TC_CCR_CLKDIS ;
114}
115
116/**
117 * \brief Find best MCK divisor
118 *
119 * Finds the best MCK divisor given the timer frequency and MCK. The result
120 * is guaranteed to satisfy the following equation:
121 * \code
122 * (MCK / (DIV * 65536)) <= freq <= (MCK / DIV)
123 * \endcode
124 * with DIV being the highest possible value.
125 *
126 * \param dwFreq Desired timer frequency.
127 * \param dwMCk Master clock frequency.
128 * \param dwDiv Divisor value.
129 * \param dwTcClks TCCLKS field value for divisor.
130 * \param dwBoardMCK Board clock frequency.
131 *
132 * \return 1 if a proper divisor has been found, otherwise 0.
133 */
134extern uint32_t TC_FindMckDivisor( uint32_t dwFreq, uint32_t dwMCk, uint32_t *dwDiv, uint32_t *dwTcClks, uint32_t dwBoardMCK )
135{
136 const uint32_t adwDivisors[5] = { 2, 8, 32, 128, dwBoardMCK / 32768 } ;
137
138 uint32_t dwIndex = 0 ;
139
140 /* Satisfy lower bound */
141 while ( dwFreq < ((dwMCk / adwDivisors[dwIndex]) / 65536) )
142 {
143 dwIndex++ ;
144
145 /* If no divisor can be found, return 0 */
146 if ( dwIndex == (sizeof( adwDivisors )/sizeof( adwDivisors[0] )) )
147 {
148 return 0 ;
149 }
150 }
151
152 /* Try to maximize DIV while satisfying upper bound */
153 while ( dwIndex < 4 )
154 {
155
156 if ( dwFreq > (dwMCk / adwDivisors[dwIndex + 1]) )
157 {
158 break ;
159 }
160 dwIndex++ ;
161 }
162
163 /* Store results */
164 if ( dwDiv )
165 {
166 *dwDiv = adwDivisors[dwIndex] ;
167 }
168 if ( dwTcClks )
169 {
170 *dwTcClks = dwIndex ;
171 }
172
173 return 1 ;
174}
175