2 * (C) Copyright 2007-2008
3 * Stelian Pop <stelian@popies.net>
4 * Lead Tech Design <www.leadtechdesign.com>
6 * See file CREDITS for list of people who contributed to this
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License as
11 * published by the Free Software Foundation; either version 2 of
12 * the License, or (at your option) any later version.
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
27 #include <asm/arch/hardware.h>
28 #include <asm/arch/at91_pit.h>
29 #include <asm/arch/at91_pmc.h>
30 #include <asm/arch/clk.h>
33 #if !defined(CONFIG_AT91FAMILY)
34 # error You need to define CONFIG_AT91FAMILY in your board config!
37 DECLARE_GLOBAL_DATA_PTR;
40 * We're using the AT91CAP9/SAM9 PITC in 32 bit mode, by
41 * setting the 20 bit counter period to its maximum (0xfffff).
42 * (See the relevant data sheets to understand that this really works)
44 * We do also mimic the typical powerpc way of incrementing
45 * two 32 bit registers called tbl and tbu.
47 * Those registers increment at 1/16 the main clock rate.
50 #define TIMER_LOAD_VAL 0xfffff
52 static inline unsigned long long tick_to_time(unsigned long long tick)
54 tick *= CONFIG_SYS_HZ;
55 do_div(tick, gd->arch.timer_rate_hz);
60 static inline unsigned long long usec_to_tick(unsigned long long usec)
62 usec *= gd->arch.timer_rate_hz;
63 do_div(usec, 1000000);
69 * Use the PITC in full 32 bit incrementing mode
73 at91_pmc_t *pmc = (at91_pmc_t *) ATMEL_BASE_PMC;
74 at91_pit_t *pit = (at91_pit_t *) ATMEL_BASE_PIT;
76 /* Enable PITC Clock */
77 writel(1 << ATMEL_ID_SYS, &pmc->pcer);
80 writel(TIMER_LOAD_VAL | AT91_PIT_MR_EN , &pit->mr);
82 gd->arch.timer_rate_hz = gd->arch.mck_rate_hz / 16;
83 gd->tbu = gd->tbl = 0;
89 * Get the current 64 bit timer tick count
91 unsigned long long get_ticks(void)
93 at91_pit_t *pit = (at91_pit_t *) ATMEL_BASE_PIT;
95 ulong now = readl(&pit->piir);
97 /* increment tbu if tbl has rolled over */
101 return (((unsigned long long)gd->tbu) << 32) | gd->tbl;
104 void __udelay(unsigned long usec)
106 unsigned long long start;
109 start = get_ticks(); /* get current timestamp */
110 tmo = usec_to_tick(usec); /* convert usecs to ticks */
111 while ((get_ticks() - start) < tmo)
112 ; /* loop till time has passed */
116 * get_timer(base) can be used to check for timeouts or
117 * to measure elasped time relative to an event:
119 * ulong start_time = get_timer(0) sets start_time to the current
121 * get_timer(start_time) returns the time elapsed since then.
123 * The time is used in CONFIG_SYS_HZ units!
125 ulong get_timer(ulong base)
127 return tick_to_time(get_ticks()) - base;
131 * Return the number of timer ticks per second.
133 ulong get_tbclk(void)
135 return gd->arch.timer_rate_hz;