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- /*
- * 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,
- };
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