1 /* *****************************************************************************
2 * Copyright (C) 2016 Maxim Integrated Products, Inc., All Rights Reserved.
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
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8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice shall be included
12 * in all copies or substantial portions of the Software.
13 *
14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
15 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
16 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
17 * IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
18 * OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
19 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
20 * OTHER DEALINGS IN THE SOFTWARE.
21 *
22 * Except as contained in this notice, the name of Maxim Integrated
23 * Products, Inc. shall not be used except as stated in the Maxim Integrated
24 * Products, Inc. Branding Policy.
25 *
26 * The mere transfer of this software does not imply any licenses
27 * of trade secrets, proprietary technology, copyrights, patents,
28 * trademarks, maskwork rights, or any other form of intellectual
29 * property whatsoever. Maxim Integrated Products, Inc. retains all
30 * ownership rights.
31 *
32 * $Id: mxc_delay.c 36202 2018-07-16 21:06:02Z michael.bayern $
33 *
34 *************************************************************************** */
35
36 /* **** Includes **** */
37 #include <stdint.h>
38 #include "mxc_config.h"
39 #include "mxc_delay.h"
40
41 /* **** File Scope Variables **** */
42 static uint32_t ctrl_save;
43 static volatile uint64_t compare_value = 0;
44 static volatile uint64_t curr_value;
45 static volatile uint32_t reload;
46
47 static void mxc_delay_init(unsigned long us);
48 extern void SysTick_Handler(void);
49
50 /* ************************************************************************** */
SysTick_Handler(void)51 __weak void SysTick_Handler(void)
52 {
53 mxc_delay_handler();
54 }
55
56 /* ************************************************************************** */
mxc_delay_handler(void)57 void mxc_delay_handler(void)
58 {
59 // Check and clear overflow flag
60 if (SysTick->CTRL & SysTick_CTRL_COUNTFLAG_Msk) {
61 // Is a delay in progress?
62 if(compare_value != 0) {
63 curr_value += reload;
64 if(curr_value >= compare_value) {
65 mxc_delay_stop();
66 }
67 }
68 }
69 }
70
71 /* ************************************************************************** */
mxc_delay_init(unsigned long us)72 static void mxc_delay_init(unsigned long us)
73 {
74 uint32_t starttick, ticks;
75
76 // Record the current tick value and clear the overflow flag
77 starttick = SysTick->VAL;
78
79 // Save the state of control register (and clear the overflow flag)
80 ctrl_save = SysTick->CTRL & ~SysTick_CTRL_COUNTFLAG_Msk;
81
82 // If the SysTick is not running, configure and start it
83 if (!(SysTick->CTRL & SysTick_CTRL_ENABLE_Msk)) {
84 SysTick->LOAD = SysTick_LOAD_RELOAD_Msk;
85 SysTick->VAL = SysTick_VAL_CURRENT_Msk;
86 SysTick->CTRL = SysTick_CTRL_CLKSOURCE_Msk;
87 starttick = SysTick_VAL_CURRENT_Msk;
88 reload = SysTick_LOAD_RELOAD_Msk + 1;
89 } else {
90 reload = SysTick->LOAD + 1; // get the current reload value
91 }
92
93 // Calculate the total number of ticks to delay
94 ticks = (uint32_t)(((uint64_t)us * (uint64_t)SystemCoreClock) / 1000000);
95
96 compare_value = ticks + (reload - starttick);
97 curr_value = 0;
98
99 if (!(SysTick->CTRL & SysTick_CTRL_ENABLE_Msk)) {
100 SysTick->CTRL |= SysTick_CTRL_ENABLE_Msk;
101 }
102 }
103
104 /* ************************************************************************** */
mxc_delay_start(unsigned long us)105 int mxc_delay_start(unsigned long us)
106 {
107 // Check if timeout currently ongoing
108 if (compare_value != 0) {
109 return E_BUSY;
110 }
111
112 // Check if there is nothing to do
113 if (us == 0) {
114 return E_NO_ERROR;
115 }
116
117 // Calculate the necessary delay and start the timer
118 mxc_delay_init(us);
119
120 // Enable SysTick interrupt if necessary
121 if (compare_value != 0) {
122 SysTick->CTRL |= SysTick_CTRL_TICKINT_Msk;
123 }
124
125 return E_NO_ERROR;
126 }
127
128 /* ************************************************************************** */
mxc_delay_check(void)129 int mxc_delay_check(void)
130 {
131 // Check if timeout currently ongoing
132 if (compare_value == 0) {
133 return E_NO_ERROR;
134 }
135
136 if((curr_value + (reload - SysTick->VAL)) >= compare_value) {
137 mxc_delay_stop();
138 return E_NO_ERROR;
139 }
140
141 return E_BUSY;
142 }
143
144 /* ************************************************************************** */
mxc_delay_stop(void)145 void mxc_delay_stop(void)
146 {
147 SysTick->CTRL = ctrl_save;
148 compare_value = 0;
149 }
150
151 /* ************************************************************************** */
mxc_delay(unsigned long us)152 int mxc_delay(unsigned long us)
153 {
154 // Check if timeout currently ongoing
155 if (compare_value != 0) {
156 return E_BUSY;
157 }
158
159 // Check if there is nothing to do
160 if (us == 0) {
161 return E_NO_ERROR;
162 }
163
164 // Calculate the necessary delay and start the timer
165 mxc_delay_init(us);
166
167 // Wait until the total number of ticks exceeds the compare value.
168 while ((curr_value + (reload - SysTick->VAL)) < compare_value) {
169 // If SysTick interrupts are enabled, COUNTFLAG will never be set here and
170 // curr_value will be incremented in the ISR. If SysTick interrupts are
171 // disabled, curr_value is incremented here.
172 if (SysTick->CTRL & SysTick_CTRL_COUNTFLAG_Msk) {
173 curr_value += reload;
174 }
175 }
176
177 mxc_delay_stop();
178 return E_NO_ERROR;
179 }
180