1 /*
2 * (C) Copyright 2007
3 * Sascha Hauer, Pengutronix
4 *
5 * See file CREDITS for list of people who contributed to this
6 * project.
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2 of
11 * the License, or (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
21 * MA 02111-1307 USA
22 */
24 #include <common.h>
25 #include <asm/arch/imx-regs.h>
26 #include <asm/arch/clock.h>
27 #include <div64.h>
28 #include <watchdog.h>
29 #include <asm/io.h>
31 #define TIMER_BASE 0x53f90000 /* General purpose timer 1 */
33 /* General purpose timers registers */
34 #define GPTCR __REG(TIMER_BASE) /* Control register */
35 #define GPTPR __REG(TIMER_BASE + 0x4) /* Prescaler register */
36 #define GPTSR __REG(TIMER_BASE + 0x8) /* Status register */
37 #define GPTCNT __REG(TIMER_BASE + 0x24) /* Counter register */
39 /* General purpose timers bitfields */
40 #define GPTCR_SWR (1 << 15) /* Software reset */
41 #define GPTCR_FRR (1 << 9) /* Freerun / restart */
42 #define GPTCR_CLKSOURCE_32 (4 << 6) /* Clock source */
43 #define GPTCR_TEN 1 /* Timer enable */
45 DECLARE_GLOBAL_DATA_PTR;
47 /*
48 * "time" is measured in 1 / CONFIG_SYS_HZ seconds,
49 * "tick" is internal timer period
50 */
52 #ifdef CONFIG_MX31_TIMER_HIGH_PRECISION
53 /* ~0.4% error - measured with stop-watch on 100s boot-delay */
54 static inline unsigned long long tick_to_time(unsigned long long tick)
55 {
56 tick *= CONFIG_SYS_HZ;
57 do_div(tick, MXC_CLK32);
58 return tick;
59 }
61 static inline unsigned long long time_to_tick(unsigned long long time)
62 {
63 time *= MXC_CLK32;
64 do_div(time, CONFIG_SYS_HZ);
65 return time;
66 }
68 static inline unsigned long long us_to_tick(unsigned long long us)
69 {
70 us = us * MXC_CLK32 + 999999;
71 do_div(us, 1000000);
72 return us;
73 }
74 #else
75 /* ~2% error */
76 #define TICK_PER_TIME ((MXC_CLK32 + CONFIG_SYS_HZ / 2) / CONFIG_SYS_HZ)
77 #define US_PER_TICK (1000000 / MXC_CLK32)
79 static inline unsigned long long tick_to_time(unsigned long long tick)
80 {
81 do_div(tick, TICK_PER_TIME);
82 return tick;
83 }
85 static inline unsigned long long time_to_tick(unsigned long long time)
86 {
87 return time * TICK_PER_TIME;
88 }
90 static inline unsigned long long us_to_tick(unsigned long long us)
91 {
92 us += US_PER_TICK - 1;
93 do_div(us, US_PER_TICK);
94 return us;
95 }
96 #endif
98 /* The 32768Hz 32-bit timer overruns in 131072 seconds */
99 int timer_init(void)
100 {
101 int i;
103 /* setup GP Timer 1 */
104 GPTCR = GPTCR_SWR;
105 for (i = 0; i < 100; i++)
106 GPTCR = 0; /* We have no udelay by now */
107 GPTPR = 0; /* 32Khz */
108 /* Freerun Mode, PERCLK1 input */
109 GPTCR |= GPTCR_CLKSOURCE_32 | GPTCR_TEN;
111 return 0;
112 }
114 unsigned long long get_ticks(void)
115 {
116 ulong now = GPTCNT; /* current tick value */
118 if (now >= gd->arch.lastinc) /* normal mode (non roll) */
119 /* move stamp forward with absolut diff ticks */
120 gd->arch.tbl += (now - gd->arch.lastinc);
121 else /* we have rollover of incrementer */
122 gd->arch.tbl += (0xFFFFFFFF - gd->arch.lastinc) + now;
123 gd->arch.lastinc = now;
124 return gd->arch.tbl;
125 }
127 ulong get_timer_masked(void)
128 {
129 /*
130 * get_ticks() returns a long long (64 bit), it wraps in
131 * 2^64 / MXC_CLK32 = 2^64 / 2^15 = 2^49 ~ 5 * 10^14 (s) ~
132 * 5 * 10^9 days... and get_ticks() * CONFIG_SYS_HZ wraps in
133 * 5 * 10^6 days - long enough.
134 */
135 return tick_to_time(get_ticks());
136 }
138 ulong get_timer(ulong base)
139 {
140 return get_timer_masked() - base;
141 }
143 /* delay x useconds AND preserve advance timestamp value */
144 void __udelay(unsigned long usec)
145 {
146 unsigned long long tmp;
147 ulong tmo;
149 tmo = us_to_tick(usec);
150 tmp = get_ticks() + tmo; /* get current timestamp */
152 while (get_ticks() < tmp) /* loop till event */
153 /*NOP*/;
154 }
156 /*
157 * This function is derived from PowerPC code (timebase clock frequency).
158 * On ARM it returns the number of timer ticks per second.
159 */
160 ulong get_tbclk(void)
161 {
162 return MXC_CLK32;
163 }