| 1 | /* |
| 2 | * arch/ubicom32/kernel/time.c |
| 3 | * Initialize the timer list and start the appropriate timers. |
| 4 | * |
| 5 | * (C) Copyright 2009, Ubicom, Inc. |
| 6 | * Copyright (C) 1991, 1992, 1995 Linus Torvalds |
| 7 | * |
| 8 | * This file is part of the Ubicom32 Linux Kernel Port. |
| 9 | * |
| 10 | * The Ubicom32 Linux Kernel Port is free software: you can redistribute |
| 11 | * it and/or modify it under the terms of the GNU General Public License |
| 12 | * as published by the Free Software Foundation, either version 2 of the |
| 13 | * License, or (at your option) any later version. |
| 14 | * |
| 15 | * The Ubicom32 Linux Kernel Port is distributed in the hope that it |
| 16 | * will be useful, but WITHOUT ANY WARRANTY; without even the implied |
| 17 | * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See |
| 18 | * the GNU General Public License for more details. |
| 19 | * |
| 20 | * You should have received a copy of the GNU General Public License |
| 21 | * along with the Ubicom32 Linux Kernel Port. If not, |
| 22 | * see <http://www.gnu.org/licenses/>. |
| 23 | * |
| 24 | * Ubicom32 implementation derived from (with many thanks): |
| 25 | * arch/m68knommu |
| 26 | * arch/blackfin |
| 27 | * arch/parisc |
| 28 | */ |
| 29 | |
| 30 | #include <linux/profile.h> |
| 31 | #include <linux/smp.h> |
| 32 | #include <asm/ip5000.h> |
| 33 | #include <asm/machdep.h> |
| 34 | |
| 35 | /* |
| 36 | * A bitmap of the timers on the processor indicates |
| 37 | * that the timer is free or in-use. |
| 38 | */ |
| 39 | static unsigned int timers; |
| 40 | |
| 41 | /* |
| 42 | * timer_set() |
| 43 | * Init the specified compare register to go off <n> cycles from now. |
| 44 | */ |
| 45 | void timer_set(int timervector, unsigned int cycles) |
| 46 | { |
| 47 | int idx = UBICOM32_VECTOR_TO_TIMER_INDEX(timervector); |
| 48 | UBICOM32_IO_TIMER->syscom[idx] = |
| 49 | UBICOM32_IO_TIMER->sysval + cycles; |
| 50 | ldsr_enable_vector(timervector); |
| 51 | } |
| 52 | |
| 53 | /* |
| 54 | * timer_reset() |
| 55 | * Set/reset the timer to go off again. |
| 56 | * |
| 57 | * Because sysval is a continuous timer, this function is able |
| 58 | * to ensure that we do not have clock sku by using the previous |
| 59 | * value in syscom to set the next value for syscom. |
| 60 | * |
| 61 | * Returns the number of ticks that transpired since the last event. |
| 62 | */ |
| 63 | int timer_reset(int timervector, unsigned int cycles) |
| 64 | { |
| 65 | /* |
| 66 | * Reset the timer in the LDSR thread to go off appropriately. |
| 67 | * |
| 68 | * Use the previous value of the timer to calculate the new stop |
| 69 | * time. This allows us to account for it taking an |
| 70 | * indeterminate amount of time to get here. |
| 71 | */ |
| 72 | const int timer_index = UBICOM32_VECTOR_TO_TIMER_INDEX(timervector); |
| 73 | unsigned int prev = UBICOM32_IO_TIMER->syscom[timer_index]; |
| 74 | unsigned int next = prev + cycles; |
| 75 | int scratchpad3; |
| 76 | int diff; |
| 77 | int ticks = 1; |
| 78 | |
| 79 | /* |
| 80 | * If the difference is negative, we have missed at least one |
| 81 | * timer tick. |
| 82 | * |
| 83 | * TODO: Decide if we want to "ignore" time (as done below) or |
| 84 | * if we want to process time (unevenly) by calling timer_tick() |
| 85 | * lost_ticks times. |
| 86 | */ |
| 87 | while (1) { |
| 88 | /* |
| 89 | * Set our future time first. |
| 90 | */ |
| 91 | UBICOM32_IO_TIMER->syscom[timer_index] = next; |
| 92 | |
| 93 | /* |
| 94 | * Then check if we are really set time in the futrue. |
| 95 | */ |
| 96 | diff = (int)next - (int)UBICOM32_IO_TIMER->sysval; |
| 97 | if (diff >= 0) { |
| 98 | break; |
| 99 | } |
| 100 | |
| 101 | /* |
| 102 | * Oops, we are too slow. Playing catch up. |
| 103 | * |
| 104 | * If the debugger is connected the there is a good |
| 105 | * chance that we lost time because we were in a |
| 106 | * break-point, so in this case we do not print out |
| 107 | * diagnostics. |
| 108 | */ |
| 109 | asm volatile ("move.4 %0, scratchpad3" |
| 110 | : "=r" (scratchpad3)); |
| 111 | if ((scratchpad3 & 0x1) == 0) { |
| 112 | /* |
| 113 | * No debugger attached, print to the console |
| 114 | */ |
| 115 | printk(KERN_EMERG "diff: %d, timer has lost %u " |
| 116 | "ticks [rounded up]\n", |
| 117 | -diff, |
| 118 | (unsigned int)((-diff + cycles - 1) / cycles)); |
| 119 | } |
| 120 | |
| 121 | do { |
| 122 | next += cycles; |
| 123 | diff = (int)next - (int)UBICOM32_IO_TIMER->sysval; |
| 124 | ticks++; |
| 125 | } while (diff < 0); |
| 126 | } |
| 127 | return ticks; |
| 128 | } |
| 129 | |
| 130 | /* |
| 131 | * sched_clock() |
| 132 | * Returns current time in nano-second units. |
| 133 | * |
| 134 | * Notes: |
| 135 | * 1) This is an override for the weak alias in |
| 136 | * kernel/sched_clock.c. |
| 137 | * 2) Do not use xtime_lock as this function is |
| 138 | * sometimes called with xtime_lock held. |
| 139 | * 3) We use a retry algorithm to ensure that |
| 140 | * we get a consistent value. |
| 141 | * 4) sched_clock must be overwritten if IRQ tracing |
| 142 | * is enabled because the default implementation uses |
| 143 | * the xtime_lock sequence while holding xtime_lock. |
| 144 | */ |
| 145 | unsigned long long sched_clock(void) |
| 146 | { |
| 147 | unsigned long long my_jiffies; |
| 148 | unsigned long jiffies_top; |
| 149 | unsigned long jiffies_bottom; |
| 150 | |
| 151 | do { |
| 152 | jiffies_top = jiffies_64 >> 32; |
| 153 | jiffies_bottom = jiffies_64 & 0xffffffff; |
| 154 | } while (unlikely(jiffies_top != (unsigned long)(jiffies_64 >> 32))); |
| 155 | |
| 156 | my_jiffies = ((unsigned long long)jiffies_top << 32) | (jiffies_bottom); |
| 157 | return (my_jiffies - INITIAL_JIFFIES) * (NSEC_PER_SEC / HZ); |
| 158 | } |
| 159 | |
| 160 | /* |
| 161 | * timer_free() |
| 162 | * Free a hardware timer. |
| 163 | */ |
| 164 | void timer_free(int interrupt) |
| 165 | { |
| 166 | unsigned int bit = interrupt - TIMER_INT(0); |
| 167 | |
| 168 | /* |
| 169 | * The timer had not been allocated. |
| 170 | */ |
| 171 | BUG_ON(timers & (1 << bit)); |
| 172 | timers |= (1 << bit); |
| 173 | } |
| 174 | |
| 175 | /* |
| 176 | * timer_alloc() |
| 177 | * Allocate a hardware timer. |
| 178 | */ |
| 179 | int timer_alloc(void) |
| 180 | { |
| 181 | unsigned int bit = find_first_bit((unsigned long *)&timers, 32); |
| 182 | if (!bit) { |
| 183 | printk(KERN_WARNING "no more free timers\n"); |
| 184 | return -1; |
| 185 | } |
| 186 | |
| 187 | timers &= ~(1 << bit); |
| 188 | return bit + TIMER_INT(0); |
| 189 | } |
| 190 | |
| 191 | /* |
| 192 | * time_init() |
| 193 | * Time init function. |
| 194 | */ |
| 195 | void time_init(void) |
| 196 | { |
| 197 | /* |
| 198 | * Find the processor node and determine what timers are |
| 199 | * available for us. |
| 200 | */ |
| 201 | timers = processor_timers(); |
| 202 | if (timers == 0) { |
| 203 | printk(KERN_WARNING "no timers are available for Linux\n"); |
| 204 | return; |
| 205 | } |
| 206 | |
| 207 | #ifdef CONFIG_GENERIC_CLOCKEVENTS |
| 208 | timer_device_init(); |
| 209 | #else |
| 210 | timer_tick_init(); |
| 211 | #endif |
| 212 | } |
| 213 | |
