Bryan Huntsman | 3f2bc4d | 2011-08-16 17:27:22 -0700 | [diff] [blame] | 1 | /* |
Stephen Boyd | 4d84b3b | 2012-07-26 12:00:03 -0700 | [diff] [blame] | 2 | * Delay loops based on the OpenRISC implementation. |
Bryan Huntsman | 3f2bc4d | 2011-08-16 17:27:22 -0700 | [diff] [blame] | 3 | * |
Stephen Boyd | 4d84b3b | 2012-07-26 12:00:03 -0700 | [diff] [blame] | 4 | * Copyright (C) 2012 ARM Limited |
Bryan Huntsman | 3f2bc4d | 2011-08-16 17:27:22 -0700 | [diff] [blame] | 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify |
| 7 | * it under the terms of the GNU General Public License version 2 as |
| 8 | * published by the Free Software Foundation. |
Stephen Boyd | 4d84b3b | 2012-07-26 12:00:03 -0700 | [diff] [blame] | 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | * GNU General Public License for more details. |
| 14 | * |
| 15 | * You should have received a copy of the GNU General Public License |
| 16 | * along with this program; if not, write to the Free Software |
| 17 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 18 | * |
| 19 | * Author: Will Deacon <will.deacon@arm.com> |
Bryan Huntsman | 3f2bc4d | 2011-08-16 17:27:22 -0700 | [diff] [blame] | 20 | */ |
Stephen Boyd | 4d84b3b | 2012-07-26 12:00:03 -0700 | [diff] [blame] | 21 | |
Bryan Huntsman | 3f2bc4d | 2011-08-16 17:27:22 -0700 | [diff] [blame] | 22 | #include <linux/delay.h> |
Stephen Boyd | 4d84b3b | 2012-07-26 12:00:03 -0700 | [diff] [blame] | 23 | #include <linux/init.h> |
| 24 | #include <linux/kernel.h> |
| 25 | #include <linux/module.h> |
Bryan Huntsman | 3f2bc4d | 2011-08-16 17:27:22 -0700 | [diff] [blame] | 26 | #include <linux/timex.h> |
| 27 | |
| 28 | /* |
Stephen Boyd | 4d84b3b | 2012-07-26 12:00:03 -0700 | [diff] [blame] | 29 | * Default to the loop-based delay implementation. |
Bryan Huntsman | 3f2bc4d | 2011-08-16 17:27:22 -0700 | [diff] [blame] | 30 | */ |
Stephen Boyd | 4d84b3b | 2012-07-26 12:00:03 -0700 | [diff] [blame] | 31 | struct arm_delay_ops arm_delay_ops = { |
| 32 | .delay = __loop_delay, |
| 33 | .const_udelay = __loop_const_udelay, |
| 34 | .udelay = __loop_udelay, |
| 35 | }; |
| 36 | |
| 37 | static const struct delay_timer *delay_timer; |
| 38 | static bool delay_calibrated; |
| 39 | |
| 40 | int read_current_timer(unsigned long *timer_val) |
Bryan Huntsman | 3f2bc4d | 2011-08-16 17:27:22 -0700 | [diff] [blame] | 41 | { |
Stephen Boyd | 4d84b3b | 2012-07-26 12:00:03 -0700 | [diff] [blame] | 42 | if (!delay_timer) |
| 43 | return -ENXIO; |
| 44 | |
| 45 | *timer_val = delay_timer->read_current_timer(); |
| 46 | return 0; |
| 47 | } |
| 48 | EXPORT_SYMBOL_GPL(read_current_timer); |
| 49 | |
| 50 | static void __timer_delay(unsigned long cycles) |
| 51 | { |
| 52 | cycles_t start = get_cycles(); |
| 53 | |
| 54 | while ((get_cycles() - start) < cycles) |
| 55 | cpu_relax(); |
Bryan Huntsman | 3f2bc4d | 2011-08-16 17:27:22 -0700 | [diff] [blame] | 56 | } |
| 57 | |
Stephen Boyd | 4d84b3b | 2012-07-26 12:00:03 -0700 | [diff] [blame] | 58 | static void __timer_const_udelay(unsigned long xloops) |
Bryan Huntsman | 3f2bc4d | 2011-08-16 17:27:22 -0700 | [diff] [blame] | 59 | { |
Stephen Boyd | 4d84b3b | 2012-07-26 12:00:03 -0700 | [diff] [blame] | 60 | unsigned long long loops = xloops; |
| 61 | loops *= loops_per_jiffy; |
| 62 | __timer_delay(loops >> UDELAY_SHIFT); |
Bryan Huntsman | 3f2bc4d | 2011-08-16 17:27:22 -0700 | [diff] [blame] | 63 | } |
| 64 | |
Stephen Boyd | 4d84b3b | 2012-07-26 12:00:03 -0700 | [diff] [blame] | 65 | static void __timer_udelay(unsigned long usecs) |
Bryan Huntsman | 3f2bc4d | 2011-08-16 17:27:22 -0700 | [diff] [blame] | 66 | { |
Stephen Boyd | 4d84b3b | 2012-07-26 12:00:03 -0700 | [diff] [blame] | 67 | __timer_const_udelay(usecs * UDELAY_MULT); |
Bryan Huntsman | 3f2bc4d | 2011-08-16 17:27:22 -0700 | [diff] [blame] | 68 | } |
Bryan Huntsman | 3f2bc4d | 2011-08-16 17:27:22 -0700 | [diff] [blame] | 69 | |
Stephen Boyd | 4d84b3b | 2012-07-26 12:00:03 -0700 | [diff] [blame] | 70 | void __init register_current_timer_delay(const struct delay_timer *timer) |
Bryan Huntsman | 3f2bc4d | 2011-08-16 17:27:22 -0700 | [diff] [blame] | 71 | { |
Stephen Boyd | 4d84b3b | 2012-07-26 12:00:03 -0700 | [diff] [blame] | 72 | if (!delay_calibrated) { |
| 73 | pr_info("Switching to timer-based delay loop\n"); |
| 74 | delay_timer = timer; |
| 75 | lpj_fine = timer->freq / HZ; |
| 76 | loops_per_jiffy = lpj_fine; |
| 77 | arm_delay_ops.delay = __timer_delay; |
| 78 | arm_delay_ops.const_udelay = __timer_const_udelay; |
| 79 | arm_delay_ops.udelay = __timer_udelay; |
| 80 | delay_calibrated = true; |
| 81 | } else { |
| 82 | pr_info("Ignoring duplicate/late registration of read_current_timer delay\n"); |
| 83 | } |
Bryan Huntsman | 3f2bc4d | 2011-08-16 17:27:22 -0700 | [diff] [blame] | 84 | } |
Bryan Huntsman | 3f2bc4d | 2011-08-16 17:27:22 -0700 | [diff] [blame] | 85 | |
Stephen Boyd | 4d84b3b | 2012-07-26 12:00:03 -0700 | [diff] [blame] | 86 | unsigned long __cpuinit calibrate_delay_is_known(void) |
Bryan Huntsman | 3f2bc4d | 2011-08-16 17:27:22 -0700 | [diff] [blame] | 87 | { |
Stephen Boyd | 4d84b3b | 2012-07-26 12:00:03 -0700 | [diff] [blame] | 88 | delay_calibrated = true; |
| 89 | return lpj_fine; |
Bryan Huntsman | 3f2bc4d | 2011-08-16 17:27:22 -0700 | [diff] [blame] | 90 | } |