| 1 | /* |
| 2 | * arch/ubicom32/include/asm/system.h |
| 3 | * Low level switching definitions. |
| 4 | * |
| 5 | * (C) Copyright 2009, Ubicom, Inc. |
| 6 | * |
| 7 | * This file is part of the Ubicom32 Linux Kernel Port. |
| 8 | * |
| 9 | * The Ubicom32 Linux Kernel Port is free software: you can redistribute |
| 10 | * it and/or modify it under the terms of the GNU General Public License |
| 11 | * as published by the Free Software Foundation, either version 2 of the |
| 12 | * License, or (at your option) any later version. |
| 13 | * |
| 14 | * The Ubicom32 Linux Kernel Port is distributed in the hope that it |
| 15 | * will be useful, but WITHOUT ANY WARRANTY; without even the implied |
| 16 | * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See |
| 17 | * the GNU General Public License for more details. |
| 18 | * |
| 19 | * You should have received a copy of the GNU General Public License |
| 20 | * along with the Ubicom32 Linux Kernel Port. If not, |
| 21 | * see <http://www.gnu.org/licenses/>. |
| 22 | * |
| 23 | * Ubicom32 implementation derived from (with many thanks): |
| 24 | * arch/m68knommu |
| 25 | * arch/blackfin |
| 26 | * arch/parisc |
| 27 | */ |
| 28 | #ifndef _ASM_UBICOM32_SYSTEM_H |
| 29 | #define _ASM_UBICOM32_SYSTEM_H |
| 30 | |
| 31 | #include <linux/irqflags.h> |
| 32 | #include <linux/linkage.h> |
| 33 | #include <asm/segment.h> |
| 34 | #include <asm/entry.h> |
| 35 | #include <asm/ldsr.h> |
| 36 | #include <asm/irq.h> |
| 37 | #include <asm/percpu.h> |
| 38 | #include <asm/ubicom32-common.h> |
| 39 | #include <asm/processor.h> |
| 40 | |
| 41 | /* |
| 42 | * switch_to(n) should switch tasks to task ptr, first checking that |
| 43 | * ptr isn't the current task, in which case it does nothing. |
| 44 | */ |
| 45 | asmlinkage void resume(void); |
| 46 | extern void *__switch_to(struct task_struct *prev, |
| 47 | struct thread_struct *prev_switch, |
| 48 | struct thread_struct *next_switch); |
| 49 | |
| 50 | /* |
| 51 | * We will need a per linux thread sw_ksp for the switch_to macro to |
| 52 | * track the kernel stack pointer for the current thread on that linux thread. |
| 53 | */ |
| 54 | #define switch_to(prev,next,last) \ |
| 55 | ({ \ |
| 56 | void *_last; \ |
| 57 | _last = (void *) \ |
| 58 | __switch_to(prev, &prev->thread, &next->thread); \ |
| 59 | (last) = _last; \ |
| 60 | }) |
| 61 | |
| 62 | /* |
| 63 | * Force strict CPU ordering. |
| 64 | * Not really required on ubicom32... |
| 65 | */ |
| 66 | #define nop() asm volatile ("nop"::) |
| 67 | #define mb() asm volatile ("" : : :"memory") |
| 68 | #define rmb() asm volatile ("" : : :"memory") |
| 69 | #define wmb() asm volatile ("" : : :"memory") |
| 70 | #define set_mb(var, value) ({ (var) = (value); wmb(); }) |
| 71 | |
| 72 | #ifdef CONFIG_SMP |
| 73 | #define smp_mb() mb() |
| 74 | #define smp_rmb() rmb() |
| 75 | #define smp_wmb() wmb() |
| 76 | #define smp_read_barrier_depends() read_barrier_depends() |
| 77 | #else |
| 78 | #define smp_mb() mb() |
| 79 | #define smp_rmb() rmb() |
| 80 | #define smp_wmb() wmb() |
| 81 | #define smp_read_barrier_depends() do { } while(0) |
| 82 | #endif |
| 83 | |
| 84 | #define read_barrier_depends() ((void)0) |
| 85 | |
| 86 | /* |
| 87 | * The following defines change how the scheduler calls the switch_to() |
| 88 | * macro. |
| 89 | * |
| 90 | * 1) The first causes the runqueue to be unlocked on entry to |
| 91 | * switch_to(). Since our ctx code does not play with the runqueue |
| 92 | * we do not need it unlocked. |
| 93 | * |
| 94 | * 2) The later turns interrupts on during a ctxsw to reduce the latency of |
| 95 | * interrupts during ctx. At this point in the port, we believe that this |
| 96 | * latency is not a problem since we have very little code to perform a ctxsw. |
| 97 | */ |
| 98 | // #define __ARCH_WANT_UNLOCKED_CTXSW |
| 99 | // #define __ARCH_WANT_INTERRUPTS_ON_CTXSW |
| 100 | |
| 101 | #endif /* _ASM_UBICOM32_SYSTEM_H */ |
| 102 | |
