1 /* $NetBSD: acpi_timer.c,v 1.11 2008/05/11 22:16:45 ad Exp $ */ 2 3 #include <sys/cdefs.h> 4 __KERNEL_RCSID(0, "$NetBSD: acpi_timer.c,v 1.11 2008/05/11 22:16:45 ad Exp $"); 5 6 #include <sys/types.h> 7 #include <sys/systm.h> 8 #include <sys/time.h> 9 #include <sys/timetc.h> 10 #include <dev/acpi/acpica.h> 11 #include <dev/acpi/acpi_timer.h> 12 13 static int acpitimer_test(void); 14 static uint32_t acpitimer_delta(uint32_t, uint32_t); 15 static u_int acpitimer_read_safe(struct timecounter *); 16 static u_int acpitimer_read_fast(struct timecounter *); 17 18 static struct timecounter acpi_timecounter = { 19 acpitimer_read_safe, 20 0, 21 0x00ffffff, 22 PM_TIMER_FREQUENCY, 23 "ACPI-Safe", 24 900, 25 NULL, 26 NULL, 27 }; 28 29 int 30 acpitimer_init() 31 { 32 uint32_t bits; 33 int i, j; 34 ACPI_STATUS res; 35 36 res = AcpiGetTimerResolution(&bits); 37 if (res != AE_OK) 38 return (-1); 39 40 if (bits == 32) 41 acpi_timecounter.tc_counter_mask = 0xffffffff; 42 43 j = 0; 44 for (i = 0; i < 10; i++) 45 j += acpitimer_test(); 46 47 if (j >= 10) { 48 acpi_timecounter.tc_name = "ACPI-Fast"; 49 acpi_timecounter.tc_get_timecount = acpitimer_read_fast; 50 acpi_timecounter.tc_quality = 1000; 51 } 52 53 tc_init(&acpi_timecounter); 54 aprint_verbose("%s %d-bit timer\n", acpi_timecounter.tc_name, bits); 55 56 return (0); 57 } 58 59 static u_int 60 acpitimer_read_fast(struct timecounter *tc) 61 { 62 uint32_t t; 63 64 AcpiGetTimer(&t); 65 return (t); 66 } 67 68 /* 69 * Some chipsets (PIIX4 variants) do not latch correctly; there 70 * is a chance that a transition is hit. 71 */ 72 static u_int 73 acpitimer_read_safe(struct timecounter *tc) 74 { 75 uint32_t t1, t2, t3; 76 77 AcpiGetTimer(&t2); 78 AcpiGetTimer(&t3); 79 do { 80 t1 = t2; 81 t2 = t3; 82 AcpiGetTimer(&t3); 83 } while ((t1 > t2) || (t2 > t3)); 84 return (t2); 85 } 86 87 static uint32_t 88 acpitimer_delta(uint32_t end, uint32_t start) 89 { 90 uint32_t delta; 91 u_int mask = acpi_timecounter.tc_counter_mask; 92 93 if (end >= start) 94 delta = end - start; 95 else 96 delta = ((mask - start) + end + 1) & mask; 97 98 return (delta); 99 } 100 101 #define N 2000 102 static int 103 acpitimer_test() 104 { 105 uint32_t last, this, delta; 106 int minl, maxl, n; 107 108 minl = 10000000; 109 maxl = 0; 110 111 x86_disable_intr(); 112 AcpiGetTimer(&last); 113 for (n = 0; n < N; n++) { 114 AcpiGetTimer(&this); 115 delta = acpitimer_delta(this, last); 116 if (delta > maxl) 117 maxl = delta; 118 else if (delta < minl) 119 minl = delta; 120 last = this; 121 } 122 x86_enable_intr(); 123 124 if (maxl - minl > 2 ) 125 n = 0; 126 else if (minl < 0 || maxl == 0) 127 n = 0; 128 else 129 n = 1; 130 131 return (n); 132 } 133