1 /* 2 * Copyright (c) 2015, ARM Limited and Contributors. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions are met: 6 * 7 * Redistributions of source code must retain the above copyright notice, this 8 * list of conditions and the following disclaimer. 9 * 10 * Redistributions in binary form must reproduce the above copyright notice, 11 * this list of conditions and the following disclaimer in the documentation 12 * and/or other materials provided with the distribution. 13 * 14 * Neither the name of ARM nor the names of its contributors may be used 15 * to endorse or promote products derived from this software without specific 16 * prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 19 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE 22 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28 * POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31 #include <assert.h> 32 #include <delay_timer.h> 33 #include <platform_def.h> 34 35 /*********************************************************** 36 * The delay timer implementation 37 ***********************************************************/ 38 static const timer_ops_t *ops; 39 40 /*********************************************************** 41 * Delay for the given number of microseconds. The driver must 42 * be initialized before calling this function. 43 ***********************************************************/ 44 void udelay(uint32_t usec) 45 { 46 assert(ops != 0 && 47 (ops->clk_mult != 0) && 48 (ops->clk_div != 0) && 49 (ops->get_timer_value != 0)); 50 51 uint32_t start, delta, total_delta; 52 53 assert(usec < UINT32_MAX / ops->clk_div); 54 55 start = ops->get_timer_value(); 56 57 total_delta = (usec * ops->clk_div) / ops->clk_mult; 58 59 do { 60 /* 61 * If the timer value wraps around, the subtraction will 62 * overflow and it will still give the correct result. 63 */ 64 delta = start - ops->get_timer_value(); /* Decreasing counter */ 65 66 } while (delta < total_delta); 67 } 68 69 /*********************************************************** 70 * Delay for the given number of milliseconds. The driver must 71 * be initialized before calling this function. 72 ***********************************************************/ 73 void mdelay(uint32_t msec) 74 { 75 udelay(msec*1000); 76 } 77 78 /*********************************************************** 79 * Initialize the timer. The fields in the provided timer 80 * ops pointer must be valid. 81 ***********************************************************/ 82 void timer_init(const timer_ops_t *ops_ptr) 83 { 84 assert(ops_ptr != 0 && 85 (ops_ptr->clk_mult != 0) && 86 (ops_ptr->clk_div != 0) && 87 (ops_ptr->get_timer_value != 0)); 88 89 ops = ops_ptr; 90 } 91