1 /* 2 * (C) Copyright 2007-2008 3 * Stelian Pop <stelian@popies.net> 4 * Lead Tech Design <www.leadtechdesign.com> 5 * 6 * SPDX-License-Identifier: GPL-2.0+ 7 */ 8 9 #include <common.h> 10 #include <asm/io.h> 11 #include <asm/arch/hardware.h> 12 #include <asm/arch/at91_pit.h> 13 #include <asm/arch/at91_pmc.h> 14 #include <asm/arch/clk.h> 15 #include <div64.h> 16 17 #if !defined(CONFIG_AT91FAMILY) 18 # error You need to define CONFIG_AT91FAMILY in your board config! 19 #endif 20 21 DECLARE_GLOBAL_DATA_PTR; 22 23 /* 24 * We're using the AT91CAP9/SAM9 PITC in 32 bit mode, by 25 * setting the 20 bit counter period to its maximum (0xfffff). 26 * (See the relevant data sheets to understand that this really works) 27 * 28 * We do also mimic the typical powerpc way of incrementing 29 * two 32 bit registers called tbl and tbu. 30 * 31 * Those registers increment at 1/16 the main clock rate. 32 */ 33 34 #define TIMER_LOAD_VAL 0xfffff 35 36 static inline unsigned long long tick_to_time(unsigned long long tick) 37 { 38 tick *= CONFIG_SYS_HZ; 39 do_div(tick, gd->arch.timer_rate_hz); 40 41 return tick; 42 } 43 44 static inline unsigned long long usec_to_tick(unsigned long long usec) 45 { 46 usec *= gd->arch.timer_rate_hz; 47 do_div(usec, 1000000); 48 49 return usec; 50 } 51 52 /* 53 * Use the PITC in full 32 bit incrementing mode 54 */ 55 int timer_init(void) 56 { 57 at91_pmc_t *pmc = (at91_pmc_t *) ATMEL_BASE_PMC; 58 at91_pit_t *pit = (at91_pit_t *) ATMEL_BASE_PIT; 59 60 /* Enable PITC Clock */ 61 writel(1 << ATMEL_ID_SYS, &pmc->pcer); 62 63 /* Enable PITC */ 64 writel(TIMER_LOAD_VAL | AT91_PIT_MR_EN , &pit->mr); 65 66 gd->arch.timer_rate_hz = gd->arch.mck_rate_hz / 16; 67 gd->arch.tbu = gd->arch.tbl = 0; 68 69 return 0; 70 } 71 72 /* 73 * Get the current 64 bit timer tick count 74 */ 75 unsigned long long get_ticks(void) 76 { 77 at91_pit_t *pit = (at91_pit_t *) ATMEL_BASE_PIT; 78 79 ulong now = readl(&pit->piir); 80 81 /* increment tbu if tbl has rolled over */ 82 if (now < gd->arch.tbl) 83 gd->arch.tbu++; 84 gd->arch.tbl = now; 85 return (((unsigned long long)gd->arch.tbu) << 32) | gd->arch.tbl; 86 } 87 88 void __udelay(unsigned long usec) 89 { 90 unsigned long long start; 91 ulong tmo; 92 93 start = get_ticks(); /* get current timestamp */ 94 tmo = usec_to_tick(usec); /* convert usecs to ticks */ 95 while ((get_ticks() - start) < tmo) 96 ; /* loop till time has passed */ 97 } 98 99 /* 100 * get_timer(base) can be used to check for timeouts or 101 * to measure elasped time relative to an event: 102 * 103 * ulong start_time = get_timer(0) sets start_time to the current 104 * time value. 105 * get_timer(start_time) returns the time elapsed since then. 106 * 107 * The time is used in CONFIG_SYS_HZ units! 108 */ 109 ulong get_timer(ulong base) 110 { 111 return tick_to_time(get_ticks()) - base; 112 } 113 114 /* 115 * Return the number of timer ticks per second. 116 */ 117 ulong get_tbclk(void) 118 { 119 return gd->arch.timer_rate_hz; 120 } 121