1 /* $NetBSD: acpi_timer.c,v 1.14 2009/04/08 00:15:45 dyoung Exp $ */ 2 3 #include <sys/cdefs.h> 4 __KERNEL_RCSID(0, "$NetBSD: acpi_timer.c,v 1.14 2009/04/08 00:15:45 dyoung 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 #include <machine/acpi_machdep.h> 13 14 static int acpitimer_test(void); 15 static uint32_t acpitimer_delta(uint32_t, uint32_t); 16 static u_int acpitimer_read_safe(struct timecounter *); 17 static u_int acpitimer_read_fast(struct timecounter *); 18 19 static struct timecounter acpi_timecounter = { 20 acpitimer_read_safe, 21 0, 22 0x00ffffff, 23 PM_TIMER_FREQUENCY, 24 "ACPI-Safe", 25 900, 26 NULL, 27 NULL, 28 }; 29 30 int 31 acpitimer_init(void) 32 { 33 uint32_t bits; 34 int i, j; 35 ACPI_STATUS res; 36 37 res = AcpiGetTimerResolution(&bits); 38 if (res != AE_OK) 39 return (-1); 40 41 if (bits == 32) 42 acpi_timecounter.tc_counter_mask = 0xffffffff; 43 44 j = 0; 45 for (i = 0; i < 10; i++) 46 j += acpitimer_test(); 47 48 if (j >= 10) { 49 acpi_timecounter.tc_name = "ACPI-Fast"; 50 acpi_timecounter.tc_get_timecount = acpitimer_read_fast; 51 acpi_timecounter.tc_quality = 1000; 52 } 53 54 tc_init(&acpi_timecounter); 55 aprint_verbose("%s %d-bit timer\n", acpi_timecounter.tc_name, bits); 56 57 return (0); 58 } 59 60 int 61 acpitimer_detach(void) 62 { 63 return tc_detach(&acpi_timecounter); 64 } 65 66 static u_int 67 acpitimer_read_fast(struct timecounter *tc) 68 { 69 uint32_t t; 70 71 AcpiGetTimer(&t); 72 return (t); 73 } 74 75 /* 76 * Some chipsets (PIIX4 variants) do not latch correctly; there 77 * is a chance that a transition is hit. 78 */ 79 static u_int 80 acpitimer_read_safe(struct timecounter *tc) 81 { 82 uint32_t t1, t2, t3; 83 84 AcpiGetTimer(&t2); 85 AcpiGetTimer(&t3); 86 do { 87 t1 = t2; 88 t2 = t3; 89 AcpiGetTimer(&t3); 90 } while ((t1 > t2) || (t2 > t3)); 91 return (t2); 92 } 93 94 static uint32_t 95 acpitimer_delta(uint32_t end, uint32_t start) 96 { 97 uint32_t delta; 98 u_int mask = acpi_timecounter.tc_counter_mask; 99 100 if (end >= start) 101 delta = end - start; 102 else 103 delta = ((mask - start) + end + 1) & mask; 104 105 return (delta); 106 } 107 108 #define N 2000 109 static int 110 acpitimer_test(void) 111 { 112 uint32_t last, this, delta; 113 int minl, maxl, n; 114 115 minl = 10000000; 116 maxl = 0; 117 118 acpi_md_OsDisableInterrupt(); 119 AcpiGetTimer(&last); 120 for (n = 0; n < N; n++) { 121 AcpiGetTimer(&this); 122 delta = acpitimer_delta(this, last); 123 if (delta > maxl) 124 maxl = delta; 125 else if (delta < minl) 126 minl = delta; 127 last = this; 128 } 129 acpi_md_OsEnableInterrupt(); 130 131 if (maxl - minl > 2 ) 132 n = 0; 133 else if (minl < 0 || maxl == 0) 134 n = 0; 135 else 136 n = 1; 137 138 return (n); 139 } 140