diff options
Diffstat (limited to 'drivers/acpi/hardware/hwtimer.c')
| -rw-r--r-- | drivers/acpi/hardware/hwtimer.c | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/drivers/acpi/hardware/hwtimer.c b/drivers/acpi/hardware/hwtimer.c new file mode 100644 index 000000000000..1906167d7294 --- /dev/null +++ b/drivers/acpi/hardware/hwtimer.c @@ -0,0 +1,203 @@ + +/****************************************************************************** + * + * Name: hwtimer.c - ACPI Power Management Timer Interface + * + *****************************************************************************/ + +/* + * Copyright (C) 2000 - 2005, R. Byron Moore + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions, and the following disclaimer, + * without modification. + * 2. Redistributions in binary form must reproduce at minimum a disclaimer + * substantially similar to the "NO WARRANTY" disclaimer below + * ("Disclaimer") and any redistribution must be conditioned upon + * including a substantially similar Disclaimer requirement for further + * binary redistribution. + * 3. Neither the names of the above-listed copyright holders nor the names + * of any contributors may be used to endorse or promote products derived + * from this software without specific prior written permission. + * + * Alternatively, this software may be distributed under the terms of the + * GNU General Public License ("GPL") version 2 as published by the Free + * Software Foundation. + * + * NO WARRANTY + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, + * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING + * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGES. + */ + +#include <linux/module.h> + +#include <acpi/acpi.h> + +#define _COMPONENT ACPI_HARDWARE + ACPI_MODULE_NAME ("hwtimer") + + +/****************************************************************************** + * + * FUNCTION: acpi_get_timer_resolution + * + * PARAMETERS: Resolution - Where the resolution is returned + * + * RETURN: Status and timer resolution + * + * DESCRIPTION: Obtains resolution of the ACPI PM Timer (24 or 32 bits). + * + ******************************************************************************/ + +acpi_status +acpi_get_timer_resolution ( + u32 *resolution) +{ + ACPI_FUNCTION_TRACE ("acpi_get_timer_resolution"); + + + if (!resolution) { + return_ACPI_STATUS (AE_BAD_PARAMETER); + } + + if (0 == acpi_gbl_FADT->tmr_val_ext) { + *resolution = 24; + } + else { + *resolution = 32; + } + + return_ACPI_STATUS (AE_OK); +} + + +/****************************************************************************** + * + * FUNCTION: acpi_get_timer + * + * PARAMETERS: Ticks - Where the timer value is returned + * + * RETURN: Status and current ticks + * + * DESCRIPTION: Obtains current value of ACPI PM Timer (in ticks). + * + ******************************************************************************/ + +acpi_status +acpi_get_timer ( + u32 *ticks) +{ + acpi_status status; + + + ACPI_FUNCTION_TRACE ("acpi_get_timer"); + + + if (!ticks) { + return_ACPI_STATUS (AE_BAD_PARAMETER); + } + + status = acpi_hw_low_level_read (32, ticks, &acpi_gbl_FADT->xpm_tmr_blk); + + return_ACPI_STATUS (status); +} +EXPORT_SYMBOL(acpi_get_timer); + + +/****************************************************************************** + * + * FUNCTION: acpi_get_timer_duration + * + * PARAMETERS: start_ticks - Starting timestamp + * end_ticks - End timestamp + * time_elapsed - Where the elapsed time is returned + * + * RETURN: Status and time_elapsed + * + * DESCRIPTION: Computes the time elapsed (in microseconds) between two + * PM Timer time stamps, taking into account the possibility of + * rollovers, the timer resolution, and timer frequency. + * + * The PM Timer's clock ticks at roughly 3.6 times per + * _microsecond_, and its clock continues through Cx state + * transitions (unlike many CPU timestamp counters) -- making it + * a versatile and accurate timer. + * + * Note that this function accommodates only a single timer + * rollover. Thus for 24-bit timers, this function should only + * be used for calculating durations less than ~4.6 seconds + * (~20 minutes for 32-bit timers) -- calculations below: + * + * 2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec + * 2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes + * + ******************************************************************************/ + +acpi_status +acpi_get_timer_duration ( + u32 start_ticks, + u32 end_ticks, + u32 *time_elapsed) +{ + acpi_status status; + u32 delta_ticks; + acpi_integer quotient; + + + ACPI_FUNCTION_TRACE ("acpi_get_timer_duration"); + + + if (!time_elapsed) { + return_ACPI_STATUS (AE_BAD_PARAMETER); + } + + /* + * Compute Tick Delta: + * Handle (max one) timer rollovers on 24-bit versus 32-bit timers. + */ + if (start_ticks < end_ticks) { + delta_ticks = end_ticks - start_ticks; + } + else if (start_ticks > end_ticks) { + if (0 == acpi_gbl_FADT->tmr_val_ext) { + /* 24-bit Timer */ + + delta_ticks = (((0x00FFFFFF - start_ticks) + end_ticks) & 0x00FFFFFF); + } + else { + /* 32-bit Timer */ + + delta_ticks = (0xFFFFFFFF - start_ticks) + end_ticks; + } + } + else /* start_ticks == end_ticks */ { + *time_elapsed = 0; + return_ACPI_STATUS (AE_OK); + } + + /* + * Compute Duration (Requires a 64-bit multiply and divide): + * + * time_elapsed = (delta_ticks * 1000000) / PM_TIMER_FREQUENCY; + */ + status = acpi_ut_short_divide (((u64) delta_ticks) * 1000000, + PM_TIMER_FREQUENCY, "ient, NULL); + + *time_elapsed = (u32) quotient; + return_ACPI_STATUS (status); +} +EXPORT_SYMBOL(acpi_get_timer_duration); + |
