acpi/acpica/hwtimer.c

4  * Name: hwtimer.c - ACPI Power Management Timer Interface
9  * Copyright (C) 2000 - 2012, Intel Corp.
23  * 3. Neither the names of the above-listed copyright holders nor the names
56  * PARAMETERS:  Resolution          - Where the resolution is returned
86  * PARAMETERS:  Ticks               - Where the timer value is returned  in ACPI_EXPORT_SYMBOL()
115  * PARAMETERS:  start_ticks         - Starting timestamp  in ACPI_EXPORT_SYMBOL()
116  *              end_ticks           - End timestamp  in ACPI_EXPORT_SYMBOL()
117  *              time_elapsed        - Where the elapsed time is returned  in ACPI_EXPORT_SYMBOL()
125  *              The PM Timer's clock ticks at roughly 3.6 times per  in ACPI_EXPORT_SYMBOL()
126  *              _microsecond_, and its clock continues through Cx state  in ACPI_EXPORT_SYMBOL()
127  *              transitions (unlike many CPU timestamp counters) -- making it  in ACPI_EXPORT_SYMBOL()
131  *              rollover.  Thus for 24-bit timers, this function should only  in ACPI_EXPORT_SYMBOL()
133  *              (~20 minutes for 32-bit timers) -- calculations below:  in ACPI_EXPORT_SYMBOL()
154 	 * Handle (max one) timer rollovers on 24-bit versus 32-bit timers.  in ACPI_EXPORT_SYMBOL()
157 		delta_ticks = end_ticks - start_ticks;  in ACPI_EXPORT_SYMBOL()
161 			/* 24-bit Timer */  in ACPI_EXPORT_SYMBOL()
164 			    (((0x00FFFFFF - start_ticks) +  in ACPI_EXPORT_SYMBOL()
167 			/* 32-bit Timer */  in ACPI_EXPORT_SYMBOL()
169 			delta_ticks = (0xFFFFFFFF - start_ticks) + end_ticks;  in ACPI_EXPORT_SYMBOL()
178 	 * Compute Duration (Requires a 64-bit multiply and divide):  in ACPI_EXPORT_SYMBOL()