1 /* $NetBSD: acpi_timer.c,v 1.13 2009/03/15 15:42:55 cegger Exp $ */ 2 3 #include <sys/cdefs.h> 4 __KERNEL_RCSID(0, "$NetBSD: acpi_timer.c,v 1.13 2009/03/15 15:42:55 cegger 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 static u_int 61 acpitimer_read_fast(struct timecounter *tc) 62 { 63 uint32_t t; 64 65 AcpiGetTimer(&t); 66 return (t); 67 } 68 69 /* 70 * Some chipsets (PIIX4 variants) do not latch correctly; there 71 * is a chance that a transition is hit. 72 */ 73 static u_int 74 acpitimer_read_safe(struct timecounter *tc) 75 { 76 uint32_t t1, t2, t3; 77 78 AcpiGetTimer(&t2); 79 AcpiGetTimer(&t3); 80 do { 81 t1 = t2; 82 t2 = t3; 83 AcpiGetTimer(&t3); 84 } while ((t1 > t2) || (t2 > t3)); 85 return (t2); 86 } 87 88 static uint32_t 89 acpitimer_delta(uint32_t end, uint32_t start) 90 { 91 uint32_t delta; 92 u_int mask = acpi_timecounter.tc_counter_mask; 93 94 if (end >= start) 95 delta = end - start; 96 else 97 delta = ((mask - start) + end + 1) & mask; 98 99 return (delta); 100 } 101 102 #define N 2000 103 static int 104 acpitimer_test(void) 105 { 106 uint32_t last, this, delta; 107 int minl, maxl, n; 108 109 minl = 10000000; 110 maxl = 0; 111 112 acpi_md_OsDisableInterrupt(); 113 AcpiGetTimer(&last); 114 for (n = 0; n < N; n++) { 115 AcpiGetTimer(&this); 116 delta = acpitimer_delta(this, last); 117 if (delta > maxl) 118 maxl = delta; 119 else if (delta < minl) 120 minl = delta; 121 last = this; 122 } 123 acpi_md_OsEnableInterrupt(); 124 125 if (maxl - minl > 2 ) 126 n = 0; 127 else if (minl < 0 || maxl == 0) 128 n = 0; 129 else 130 n = 1; 131 132 return (n); 133 } 134