| /* |
| * Copyright (C) 2018 Michael Brown <mbrown@fensystems.co.uk>. |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License as |
| * published by the Free Software Foundation; either version 2 of the |
| * License, or any later version. |
| * |
| * This program is distributed in the hope that it will be useful, but |
| * WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| * 02110-1301, USA. |
| * |
| * You can also choose to distribute this program under the terms of |
| * the Unmodified Binary Distribution Licence (as given in the file |
| * COPYING.UBDL), provided that you have satisfied its requirements. |
| */ |
| |
| FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL ); |
| |
| #include <unistd.h> |
| #include <errno.h> |
| #include <assert.h> |
| #include <byteswap.h> |
| #include <ipxe/io.h> |
| #include <ipxe/acpi.h> |
| |
| /** @file |
| * |
| * ACPI power management timer |
| * |
| */ |
| |
| /** ACPI timer frequency (fixed 3.579545MHz) */ |
| #define ACPI_TIMER_HZ 3579545 |
| |
| /** ACPI timer mask |
| * |
| * Timers may be implemented as either 24-bit or 32-bit counters. We |
| * simplify the code by pessimistically assuming that the timer has |
| * only 24 bits. |
| */ |
| #define ACPI_TIMER_MASK 0x00ffffffUL |
| |
| /** Power management timer register address */ |
| static unsigned int pm_tmr; |
| |
| struct timer acpi_timer __timer ( TIMER_PREFERRED ); |
| |
| /** |
| * Get current system time in ticks |
| * |
| * @ret ticks Current time, in ticks |
| */ |
| static unsigned long acpi_currticks ( void ) { |
| static unsigned long offset; |
| static uint32_t prev; |
| uint32_t now; |
| |
| /* Read timer and account for wraparound */ |
| now = ( inl ( pm_tmr ) & ACPI_TIMER_MASK ); |
| if ( now < prev ) { |
| offset += ( ( ACPI_TIMER_MASK + 1 ) / |
| ( ACPI_TIMER_HZ / TICKS_PER_SEC ) ); |
| } |
| prev = now; |
| |
| /* Convert to timer ticks */ |
| return ( offset + ( now / ( ACPI_TIMER_HZ / TICKS_PER_SEC ) ) ); |
| } |
| |
| /** |
| * Delay for a fixed number of microseconds |
| * |
| * @v usecs Number of microseconds for which to delay |
| */ |
| static void acpi_udelay ( unsigned long usecs ) { |
| uint32_t start; |
| uint32_t elapsed; |
| uint32_t threshold; |
| |
| /* Delay until a suitable number of ticks have elapsed. We do |
| * not need to allow for multiple wraparound, since the |
| * wraparound period for a 24-bit timer at 3.579545MHz is |
| * around 4700000us. |
| */ |
| start = inl ( pm_tmr ); |
| threshold = ( ( usecs * ACPI_TIMER_HZ ) / 1000000 ); |
| do { |
| elapsed = ( ( inl ( pm_tmr ) - start ) & ACPI_TIMER_MASK ); |
| } while ( elapsed < threshold ); |
| } |
| |
| /** |
| * Probe ACPI power management timer |
| * |
| * @ret rc Return status code |
| */ |
| static int acpi_timer_probe ( void ) { |
| struct acpi_fadt fadtab; |
| userptr_t fadt; |
| unsigned int pm_tmr_blk; |
| |
| /* Locate FADT */ |
| fadt = acpi_find ( FADT_SIGNATURE, 0 ); |
| if ( ! fadt ) { |
| DBGC ( &acpi_timer, "ACPI could not find FADT\n" ); |
| return -ENOENT; |
| } |
| |
| /* Read FADT */ |
| copy_from_user ( &fadtab, fadt, 0, sizeof ( fadtab ) ); |
| pm_tmr_blk = le32_to_cpu ( fadtab.pm_tmr_blk ); |
| if ( ! pm_tmr_blk ) { |
| DBGC ( &acpi_timer, "ACPI has no timer\n" ); |
| return -ENOENT; |
| } |
| |
| /* Record power management timer register address */ |
| pm_tmr = ( pm_tmr_blk + ACPI_PM_TMR ); |
| |
| return 0; |
| } |
| |
| /** ACPI timer */ |
| struct timer acpi_timer __timer ( TIMER_PREFERRED ) = { |
| .name = "acpi", |
| .probe = acpi_timer_probe, |
| .currticks = acpi_currticks, |
| .udelay = acpi_udelay, |
| }; |