projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 1da177e4 LT |
1 | /* |
| 2 | * This file is subject to the terms and conditions of the GNU General Public | |
| 3 | * License. See the file "COPYING" in the main directory of this archive | |
| 4 | * for more details. | |
| 5 | * | |
| 6 | * Copyright (C) 1998, 1999, 2003 by Ralf Baechle | |
| 7 | */ | |
| 8 | #ifndef _ASM_TIMEX_H | |
| 9 | #define _ASM_TIMEX_H | |
| 10 | ||
| 8f9a2b32 AN |
11 | #ifdef __KERNEL__ |
| 12 | ||
| 9c9b415c | 13 | #include <asm/cpu-features.h> |
| 1da177e4 | 14 | #include <asm/mipsregs.h> |
| 9c9b415c | 15 | #include <asm/cpu-type.h> |
| 1da177e4 LT |
16 | |
| 17 | /* | |
| 72fc19ff RB |
18 | * This is the clock rate of the i8253 PIT. A MIPS system may not have |
| 19 | * a PIT by the symbol is used all over the kernel including some APIs. | |
| 20 | * So keeping it defined to the number for the PIT is the only sane thing | |
| 21 | * for now. | |
| 1da177e4 | 22 | */ |
| 72fc19ff | 23 | #define CLOCK_TICK_RATE 1193182 |
| 1da177e4 LT |
24 | |
| 25 | /* | |
| 26 | * Standard way to access the cycle counter. | |
| 27 | * Currently only used on SMP for scheduling. | |
| 28 | * | |
| 29 | * Only the low 32 bits are available as a continuously counting entity. | |
| 30 | * But this only means we'll force a reschedule every 8 seconds or so, | |
| 31 | * which isn't an evil thing. | |
| 32 | * | |
| 33 | * We know that all SMP capable CPUs have cycle counters. | |
| 34 | */ | |
| 35 | ||
| 36 | typedef unsigned int cycles_t; | |
| 37 | ||
| 9c9b415c RB |
38 | /* |
| 39 | * On R4000/R4400 before version 5.0 an erratum exists such that if the | |
| 40 | * cycle counter is read in the exact moment that it is matching the | |
| 41 | * compare register, no interrupt will be generated. | |
| 42 | * | |
| 43 | * There is a suggested workaround and also the erratum can't strike if | |
| 44 | * the compare interrupt isn't being used as the clock source device. | |
| 45 | * However for now the implementaton of this function doesn't get these | |
| 46 | * fine details right. | |
| 47 | */ | |
| 49a89efb | 48 | static inline cycles_t get_cycles(void) |
| 1da177e4 | 49 | { |
| 9c9b415c RB |
50 | switch (boot_cpu_type()) { |
| 51 | case CPU_R4400PC: | |
| 52 | case CPU_R4400SC: | |
| 53 | case CPU_R4400MC: | |
| 54 | if ((read_c0_prid() & 0xff) >= 0x0050) | |
| 55 | return read_c0_count(); | |
| 56 | break; | |
| 57 | ||
| 58 | case CPU_R4000PC: | |
| 59 | case CPU_R4000SC: | |
| 60 | case CPU_R4000MC: | |
| 61 | break; | |
| 62 | ||
| 63 | default: | |
| 64 | if (cpu_has_counter) | |
| 65 | return read_c0_count(); | |
| 66 | break; | |
| 67 | } | |
| 68 | ||
| 69 | return 0; /* no usable counter */ | |
| 1da177e4 LT |
70 | } |
| 71 | ||
| 8f9a2b32 AN |
72 | #endif /* __KERNEL__ */ |
| 73 | ||
| 1da177e4 | 74 | #endif /* _ASM_TIMEX_H */ |