1 /* 2 * Copyright (c) 2016, ARM Limited and Contributors. All rights reserved. 3 * 4 * SPDX-License-Identifier: BSD-3-Clause 5 */ 6 7 #include <m0_param.h> 8 #include "rk3399_mcu.h" 9 10 /* use 24MHz SysTick */ 11 #define US_TO_CYCLE(US) (US * 24) 12 13 #define SYST_CST 0xe000e010 14 /* enable counter */ 15 #define ENABLE (1 << 0) 16 /* count down to 0 does not cause SysTick exception to pend */ 17 #define TICKINT (1 << 1) 18 /* core clock used for SysTick */ 19 #define CLKSOURCE (1 << 2) 20 21 #define COUNTFLAG (1 << 16) 22 #define SYST_RVR 0xe000e014 23 #define MAX_VALUE 0xffffff 24 #define MAX_USECS (MAX_VALUE / US_TO_CYCLE(1)) 25 #define SYST_CVR 0xe000e018 26 #define SYST_CALIB 0xe000e01c 27 28 unsigned int remaining_usecs; 29 30 static inline void stopwatch_set_usecs(void) 31 { 32 unsigned int cycle; 33 unsigned int usecs = MIN(MAX_USECS, remaining_usecs); 34 35 remaining_usecs -= usecs; 36 cycle = US_TO_CYCLE(usecs); 37 mmio_write_32(SYST_RVR, cycle); 38 mmio_write_32(SYST_CVR, 0); 39 40 mmio_write_32(SYST_CST, ENABLE | TICKINT | CLKSOURCE); 41 } 42 43 void stopwatch_init_usecs_expire(unsigned int usecs) 44 { 45 /* 46 * Enter an inifite loop if the stopwatch is in use. This will allow the 47 * state to be analyzed with a debugger. 48 */ 49 if (mmio_read_32(SYST_CST) & ENABLE) 50 while (1) 51 ; 52 53 remaining_usecs = usecs; 54 stopwatch_set_usecs(); 55 } 56 57 int stopwatch_expired(void) 58 { 59 int val = mmio_read_32(SYST_CST); 60 if ((val & COUNTFLAG) || !(val & ENABLE)) { 61 if (!remaining_usecs) 62 return 1; 63 64 stopwatch_set_usecs(); 65 } 66 67 return 0; 68 } 69 70 void stopwatch_reset(void) 71 { 72 mmio_clrbits_32(SYST_CST, ENABLE); 73 remaining_usecs = 0; 74 } 75
