[time] Add support for the ACPI power management timer

Allow the ACPI power management timer to be used if enabled via
TIMER_ACPI in config/timer.h.  This provides an alternative timer on
systems where the standard 8254 PIT is unavailable or unreliable.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/arch/x86/include/bits/errfile.h b/src/arch/x86/include/bits/errfile.h
index 9d1fed7f623b59658f4f2382b3ef3dfa27a5cfbb..b0ae1abc2c31f669f99b2c9ced8db6b73c03b26d 100644 (file)
--- a/src/arch/x86/include/bits/errfile.h
+++ b/src/arch/x86/include/bits/errfile.h
@@ -27,6 +27,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #define ERRFILE_acpipwr                ( ERRFILE_ARCH | ERRFILE_CORE | 0x00100000 )
 #define ERRFILE_cpuid          ( ERRFILE_ARCH | ERRFILE_CORE | 0x00110000 )
 #define ERRFILE_rdtsc_timer    ( ERRFILE_ARCH | ERRFILE_CORE | 0x00120000 )
+#define ERRFILE_acpi_timer     ( ERRFILE_ARCH | ERRFILE_CORE | 0x00130000 )
 
 #define ERRFILE_bootsector     ( ERRFILE_ARCH | ERRFILE_IMAGE | 0x00000000 )
 #define ERRFILE_bzimage               ( ERRFILE_ARCH | ERRFILE_IMAGE | 0x00010000 )

diff --git a/src/arch/x86/interface/pcbios/acpi_timer.c b/src/arch/x86/interface/pcbios/acpi_timer.c
new file mode 100644 (file)
index 0000000..82e85a0
--- /dev/null
+++ b/src/arch/x86/interface/pcbios/acpi_timer.c
@@ -0,0 +1,136 @@
+/*
+ * 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,
+};

diff --git a/src/config/config_timer.c b/src/config/config_timer.c
index a462970c25d3040934b1a06d659d8356f8cdf330..d53c39939e18424bb7c4feb8ccd31c66328e3f8b 100644 (file)
--- a/src/config/config_timer.c
+++ b/src/config/config_timer.c
@@ -46,3 +46,6 @@ REQUIRE_OBJECT ( efi_timer );
 #ifdef TIMER_LINUX
 REQUIRE_OBJECT ( linux_timer );
 #endif
+#ifdef TIMER_ACPI
+REQUIRE_OBJECT ( acpi_timer );
+#endif

diff --git a/src/include/ipxe/acpi.h b/src/include/ipxe/acpi.h
index 68131e73ac2df63d98a345c973b22bb15fd1e20e..78f40253031dbb2b1f6428b18d07484f2cc5a32e 100644 (file)
--- a/src/include/ipxe/acpi.h
+++ b/src/include/ipxe/acpi.h
@@ -119,6 +119,10 @@ struct acpi_fadt {
        uint32_t pm1a_cnt_blk;
        /** PM1b Control Register Block */
        uint32_t pm1b_cnt_blk;
+       /** PM2 Control Register Block */
+       uint32_t pm2_cnt_blk;
+       /** PM Timer Control Register Block */
+       uint32_t pm_tmr_blk;
 } __attribute__ (( packed ));
 
 /** ACPI PM1 Control Register (within PM1a_CNT_BLK or PM1A_CNT_BLK) */
@@ -126,6 +130,9 @@ struct acpi_fadt {
 #define ACPI_PM1_CNT_SLP_TYP(x) ( (x) << 10 )  /**< Sleep type */
 #define ACPI_PM1_CNT_SLP_EN ( 1 << 13 )                /**< Sleep enable */
 
+/** ACPI PM Timer Register (within PM_TMR_BLK) */
+#define ACPI_PM_TMR 0
+
 /** Differentiated System Description Table (DSDT) signature */
 #define DSDT_SIGNATURE ACPI_SIGNATURE ( 'D', 'S', 'D', 'T' )