1 /* 2 * (C) Copyright 2007 3 * Sascha Hauer, Pengutronix 4 * 5 * (C) Copyright 2008-2009 Freescale Semiconductor, Inc. 6 * 7 * See file CREDITS for list of people who contributed to this 8 * project. 9 * 10 * This program is free software; you can redistribute it and/or 11 * modify it under the terms of the GNU General Public License as 12 * published by the Free Software Foundation; either version 2 of 13 * the License, or (at your option) any later version. 14 * 15 * This program is distributed in the hope that it will be useful, 16 * but WITHOUT ANY WARRANTY; without even the implied warranty of 17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 18 * GNU General Public License for more details. 19 * 20 * You should have received a copy of the GNU General Public License 21 * along with this program; if not, write to the Free Software 22 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, 23 * MA 02111-1307 USA 24 */ 25 26 #include <common.h> 27 #include <asm/io.h> 28 #include <div64.h> 29 #include <asm/arch/imx-regs.h> 30 #include <asm/arch/crm_regs.h> 31 #include <asm/arch/clock.h> 32 33 DECLARE_GLOBAL_DATA_PTR; 34 35 #define timestamp (gd->arch.tbl) 36 #define lastinc (gd->arch.lastinc) 37 38 /* General purpose timers bitfields */ 39 #define GPTCR_SWR (1<<15) /* Software reset */ 40 #define GPTCR_FRR (1<<9) /* Freerun / restart */ 41 #define GPTCR_CLKSOURCE_32 (4<<6) /* Clock source */ 42 #define GPTCR_TEN (1) /* Timer enable */ 43 44 /* 45 * "time" is measured in 1 / CONFIG_SYS_HZ seconds, 46 * "tick" is internal timer period 47 */ 48 /* ~0.4% error - measured with stop-watch on 100s boot-delay */ 49 static inline unsigned long long tick_to_time(unsigned long long tick) 50 { 51 tick *= CONFIG_SYS_HZ; 52 do_div(tick, MXC_CLK32); 53 54 return tick; 55 } 56 57 static inline unsigned long long us_to_tick(unsigned long long us) 58 { 59 us = us * MXC_CLK32 + 999999; 60 do_div(us, 1000000); 61 62 return us; 63 } 64 65 /* 66 * nothing really to do with interrupts, just starts up a counter. 67 * The 32KHz 32-bit timer overruns in 134217 seconds 68 */ 69 int timer_init(void) 70 { 71 int i; 72 struct gpt_regs *gpt = (struct gpt_regs *)GPT1_BASE_ADDR; 73 struct ccm_regs *ccm = (struct ccm_regs *)CCM_BASE_ADDR; 74 75 /* setup GP Timer 1 */ 76 writel(GPTCR_SWR, &gpt->ctrl); 77 78 writel(readl(&ccm->cgr1) | 3 << MXC_CCM_CGR1_GPT_OFFSET, &ccm->cgr1); 79 80 for (i = 0; i < 100; i++) 81 writel(0, &gpt->ctrl); /* We have no udelay by now */ 82 writel(0, &gpt->pre); /* prescaler = 1 */ 83 /* Freerun Mode, 32KHz input */ 84 writel(readl(&gpt->ctrl) | GPTCR_CLKSOURCE_32 | GPTCR_FRR, 85 &gpt->ctrl); 86 writel(readl(&gpt->ctrl) | GPTCR_TEN, &gpt->ctrl); 87 88 return 0; 89 } 90 91 unsigned long long get_ticks(void) 92 { 93 struct gpt_regs *gpt = (struct gpt_regs *)GPT1_BASE_ADDR; 94 ulong now = readl(&gpt->counter); /* current tick value */ 95 96 if (now >= lastinc) { 97 /* 98 * normal mode (non roll) 99 * move stamp forward with absolut diff ticks 100 */ 101 timestamp += (now - lastinc); 102 } else { 103 /* we have rollover of incrementer */ 104 timestamp += (0xFFFFFFFF - lastinc) + now; 105 } 106 lastinc = now; 107 return timestamp; 108 } 109 110 ulong get_timer_masked(void) 111 { 112 /* 113 * get_ticks() returns a long long (64 bit), it wraps in 114 * 2^64 / MXC_CLK32 = 2^64 / 2^15 = 2^49 ~ 5 * 10^14 (s) ~ 115 * 5 * 10^9 days... and get_ticks() * CONFIG_SYS_HZ wraps in 116 * 5 * 10^6 days - long enough. 117 */ 118 return tick_to_time(get_ticks()); 119 } 120 121 ulong get_timer(ulong base) 122 { 123 return get_timer_masked() - base; 124 } 125 126 /* delay x useconds AND preserve advance timstamp value */ 127 void __udelay(unsigned long usec) 128 { 129 unsigned long long tmp; 130 ulong tmo; 131 132 tmo = us_to_tick(usec); 133 tmp = get_ticks() + tmo; /* get current timestamp */ 134 135 while (get_ticks() < tmp) /* loop till event */ 136 /*NOP*/; 137 } 138 139 /* 140 * This function is derived from PowerPC code (timebase clock frequency). 141 * On ARM it returns the number of timer ticks per second. 142 */ 143 ulong get_tbclk(void) 144 { 145 return MXC_CLK32; 146 } 147