1 /*
2  * Copyright (c) 2015, ARM Limited and Contributors. All rights reserved.
3  *
4  * SPDX-License-Identifier: BSD-3-Clause
5  */
6 
7 #include <assert.h>
8 #include <delay_timer.h>
9 #include <platform_def.h>
10 
11 /***********************************************************
12  * The delay timer implementation
13  ***********************************************************/
14 static const timer_ops_t *ops;
15 
16 /***********************************************************
17  * Delay for the given number of microseconds. The driver must
18  * be initialized before calling this function.
19  ***********************************************************/
udelay(uint32_t usec)20 void udelay(uint32_t usec)
21 {
22 	assert(ops != NULL &&
23 		(ops->clk_mult != 0) &&
24 		(ops->clk_div != 0) &&
25 		(ops->get_timer_value != NULL));
26 
27 	uint32_t start, delta, total_delta;
28 
29 	assert(usec < UINT32_MAX / ops->clk_div);
30 
31 	start = ops->get_timer_value();
32 
33 	total_delta = (usec * ops->clk_div) / ops->clk_mult;
34 
35 	do {
36 		/*
37 		 * If the timer value wraps around, the subtraction will
38 		 * overflow and it will still give the correct result.
39 		 */
40 		delta = start - ops->get_timer_value(); /* Decreasing counter */
41 
42 	} while (delta < total_delta);
43 }
44 
45 /***********************************************************
46  * Delay for the given number of milliseconds. The driver must
47  * be initialized before calling this function.
48  ***********************************************************/
mdelay(uint32_t msec)49 void mdelay(uint32_t msec)
50 {
51 	udelay(msec*1000);
52 }
53 
54 /***********************************************************
55  * Initialize the timer. The fields in the provided timer
56  * ops pointer must be valid.
57  ***********************************************************/
timer_init(const timer_ops_t * ops_ptr)58 void timer_init(const timer_ops_t *ops_ptr)
59 {
60 	assert(ops_ptr != NULL  &&
61 		(ops_ptr->clk_mult != 0) &&
62 		(ops_ptr->clk_div != 0) &&
63 		(ops_ptr->get_timer_value != NULL));
64 
65 	ops = ops_ptr;
66 }
67