1 /* $NetBSD: acpi_timer.c,v 1.9 2007/09/26 19:48:45 ad Exp $ */ 2 3 #include <sys/cdefs.h> 4 __KERNEL_RCSID(0, "$NetBSD: acpi_timer.c,v 1.9 2007/09/26 19:48:45 ad Exp $"); 5 6 #include <sys/types.h> 7 #include <dev/acpi/acpi_timer.h> 8 9 #ifdef __HAVE_TIMECOUNTER 10 11 #include <sys/systm.h> 12 #include <sys/time.h> 13 #include <sys/timetc.h> 14 #include <dev/acpi/acpica.h> 15 16 static int acpitimer_test(void); 17 static uint32_t acpitimer_delta(uint32_t, uint32_t); 18 static u_int acpitimer_read_safe(struct timecounter *); 19 static u_int acpitimer_read_fast(struct timecounter *); 20 21 static struct timecounter acpi_timecounter = { 22 acpitimer_read_safe, 23 0, 24 0x00ffffff, 25 PM_TIMER_FREQUENCY, 26 "ACPI-Safe", 27 900, 28 NULL, 29 NULL, 30 }; 31 32 int 33 acpitimer_init() 34 { 35 uint32_t bits; 36 int i, j; 37 ACPI_STATUS res; 38 39 res = AcpiGetTimerResolution(&bits); 40 if (res != AE_OK) 41 return (-1); 42 43 if (bits == 32) 44 acpi_timecounter.tc_counter_mask = 0xffffffff; 45 46 j = 0; 47 for (i = 0; i < 10; i++) 48 j += acpitimer_test(); 49 50 if (j >= 10) { 51 acpi_timecounter.tc_name = "ACPI-Fast"; 52 acpi_timecounter.tc_get_timecount = acpitimer_read_fast; 53 acpi_timecounter.tc_quality = 1000; 54 } 55 56 tc_init(&acpi_timecounter); 57 aprint_normal("%s %d-bit timer\n", acpi_timecounter.tc_name, bits); 58 59 return (0); 60 } 61 62 static u_int 63 acpitimer_read_fast(struct timecounter *tc) 64 { 65 uint32_t t; 66 67 AcpiGetTimer(&t); 68 return (t); 69 } 70 71 /* 72 * Some chipsets (PIIX4 variants) do not latch correctly; there 73 * is a chance that a transition is hit. 74 */ 75 static u_int 76 acpitimer_read_safe(struct timecounter *tc) 77 { 78 uint32_t t1, t2, t3; 79 80 AcpiGetTimer(&t2); 81 AcpiGetTimer(&t3); 82 do { 83 t1 = t2; 84 t2 = t3; 85 AcpiGetTimer(&t3); 86 } while ((t1 > t2) || (t2 > t3)); 87 return (t2); 88 } 89 90 static uint32_t 91 acpitimer_delta(uint32_t end, uint32_t start) 92 { 93 uint32_t delta; 94 u_int mask = acpi_timecounter.tc_counter_mask; 95 96 if (end >= start) 97 delta = end - start; 98 else 99 delta = ((mask - start) + end + 1) & mask; 100 101 return (delta); 102 } 103 104 #define N 2000 105 static int 106 acpitimer_test() 107 { 108 uint32_t last, this, delta; 109 int minl, maxl, n; 110 111 minl = 10000000; 112 maxl = 0; 113 114 x86_disable_intr(); 115 AcpiGetTimer(&last); 116 for (n = 0; n < N; n++) { 117 AcpiGetTimer(&this); 118 delta = acpitimer_delta(this, last); 119 if (delta > maxl) 120 maxl = delta; 121 else if (delta < minl) 122 minl = delta; 123 last = this; 124 } 125 x86_enable_intr(); 126 127 if (maxl - minl > 2 ) 128 n = 0; 129 else if (minl < 0 || maxl == 0) 130 n = 0; 131 else 132 n = 1; 133 134 return (n); 135 } 136 137 #else 138 139 int 140 acpitimer_init() 141 { 142 143 return (0); 144 } 145 146 #endif 147