1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * Cirrus Logic EP93xx timer support. 4 * 5 * Copyright (C) 2009, 2010 Matthias Kaehlcke <matthias@kaehlcke.net> 6 * 7 * Copyright (C) 2004, 2005 8 * Cory T. Tusar, Videon Central, Inc., <ctusar@videon-central.com> 9 * 10 * Based on the original intr.c Cirrus Logic EP93xx Rev D. interrupt support, 11 * author unknown. 12 */ 13 14 #include <common.h> 15 #include <linux/types.h> 16 #include <asm/arch/ep93xx.h> 17 #include <asm/io.h> 18 #include <div64.h> 19 20 #define TIMER_CLKSEL (1 << 3) 21 #define TIMER_ENABLE (1 << 7) 22 23 #define TIMER_FREQ 508469 /* ticks / second */ 24 #define TIMER_MAX_VAL 0xFFFFFFFF 25 26 static struct ep93xx_timer 27 { 28 unsigned long long ticks; 29 unsigned long last_read; 30 } timer; 31 32 static inline unsigned long long usecs_to_ticks(unsigned long usecs) 33 { 34 unsigned long long ticks = (unsigned long long)usecs * TIMER_FREQ; 35 do_div(ticks, 1000 * 1000); 36 37 return ticks; 38 } 39 40 static inline void read_timer(void) 41 { 42 struct timer_regs *timer_regs = (struct timer_regs *)TIMER_BASE; 43 const unsigned long now = TIMER_MAX_VAL - readl(&timer_regs->timer3.value); 44 45 if (now >= timer.last_read) 46 timer.ticks += now - timer.last_read; 47 else 48 /* an overflow occurred */ 49 timer.ticks += TIMER_MAX_VAL - timer.last_read + now; 50 51 timer.last_read = now; 52 } 53 54 /* 55 * Get the number of ticks (in CONFIG_SYS_HZ resolution) 56 */ 57 unsigned long long get_ticks(void) 58 { 59 unsigned long long sys_ticks; 60 61 read_timer(); 62 63 sys_ticks = timer.ticks * CONFIG_SYS_HZ; 64 do_div(sys_ticks, TIMER_FREQ); 65 66 return sys_ticks; 67 } 68 69 unsigned long get_timer_masked(void) 70 { 71 return get_ticks(); 72 } 73 74 unsigned long get_timer(unsigned long base) 75 { 76 return get_timer_masked() - base; 77 } 78 79 void __udelay(unsigned long usec) 80 { 81 unsigned long long target; 82 83 read_timer(); 84 85 target = timer.ticks + usecs_to_ticks(usec); 86 87 while (timer.ticks < target) 88 read_timer(); 89 } 90 91 int timer_init(void) 92 { 93 struct timer_regs *timer_regs = (struct timer_regs *)TIMER_BASE; 94 95 /* use timer 3 with 508KHz and free running, not enabled now */ 96 writel(TIMER_CLKSEL, &timer_regs->timer3.control); 97 98 /* set initial timer value */ 99 writel(TIMER_MAX_VAL, &timer_regs->timer3.load); 100 101 /* Enable the timer */ 102 writel(TIMER_ENABLE | TIMER_CLKSEL, 103 &timer_regs->timer3.control); 104 105 /* Reset the timer */ 106 read_timer(); 107 timer.ticks = 0; 108 109 return 0; 110 } 111 112 /* 113 * This function is derived from PowerPC code (timebase clock frequency). 114 * On ARM it returns the number of timer ticks per second. 115 */ 116 unsigned long get_tbclk(void) 117 { 118 return CONFIG_SYS_HZ; 119 } 120