linux/arch/sparc/kernel/sun4m_irq.c
Greg Kroah-Hartman b24413180f License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-02 11:10:55 +01:00

480 lines
14 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* sun4m irq support
*
* djhr: Hacked out of irq.c into a CPU dependent version.
*
* Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
* Copyright (C) 1995 Miguel de Icaza (miguel@nuclecu.unam.mx)
* Copyright (C) 1995 Pete A. Zaitcev (zaitcev@yahoo.com)
* Copyright (C) 1996 Dave Redman (djhr@tadpole.co.uk)
*/
#include <linux/slab.h>
#include <linux/sched/debug.h>
#include <asm/timer.h>
#include <asm/traps.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/cacheflush.h>
#include "irq.h"
#include "kernel.h"
/* Sample sun4m IRQ layout:
*
* 0x22 - Power
* 0x24 - ESP SCSI
* 0x26 - Lance ethernet
* 0x2b - Floppy
* 0x2c - Zilog uart
* 0x32 - SBUS level 0
* 0x33 - Parallel port, SBUS level 1
* 0x35 - SBUS level 2
* 0x37 - SBUS level 3
* 0x39 - Audio, Graphics card, SBUS level 4
* 0x3b - SBUS level 5
* 0x3d - SBUS level 6
*
* Each interrupt source has a mask bit in the interrupt registers.
* When the mask bit is set, this blocks interrupt deliver. So you
* clear the bit to enable the interrupt.
*
* Interrupts numbered less than 0x10 are software triggered interrupts
* and unused by Linux.
*
* Interrupt level assignment on sun4m:
*
* level source
* ------------------------------------------------------------
* 1 softint-1
* 2 softint-2, VME/SBUS level 1
* 3 softint-3, VME/SBUS level 2
* 4 softint-4, onboard SCSI
* 5 softint-5, VME/SBUS level 3
* 6 softint-6, onboard ETHERNET
* 7 softint-7, VME/SBUS level 4
* 8 softint-8, onboard VIDEO
* 9 softint-9, VME/SBUS level 5, Module Interrupt
* 10 softint-10, system counter/timer
* 11 softint-11, VME/SBUS level 6, Floppy
* 12 softint-12, Keyboard/Mouse, Serial
* 13 softint-13, VME/SBUS level 7, ISDN Audio
* 14 softint-14, per-processor counter/timer
* 15 softint-15, Asynchronous Errors (broadcast)
*
* Each interrupt source is masked distinctly in the sun4m interrupt
* registers. The PIL level alone is therefore ambiguous, since multiple
* interrupt sources map to a single PIL.
*
* This ambiguity is resolved in the 'intr' property for device nodes
* in the OF device tree. Each 'intr' property entry is composed of
* two 32-bit words. The first word is the IRQ priority value, which
* is what we're intersted in. The second word is the IRQ vector, which
* is unused.
*
* The low 4 bits of the IRQ priority indicate the PIL, and the upper
* 4 bits indicate onboard vs. SBUS leveled vs. VME leveled. 0x20
* means onboard, 0x30 means SBUS leveled, and 0x40 means VME leveled.
*
* For example, an 'intr' IRQ priority value of 0x24 is onboard SCSI
* whereas a value of 0x33 is SBUS level 2. Here are some sample
* 'intr' property IRQ priority values from ss4, ss5, ss10, ss20, and
* Tadpole S3 GX systems.
*
* esp: 0x24 onboard ESP SCSI
* le: 0x26 onboard Lance ETHERNET
* p9100: 0x32 SBUS level 1 P9100 video
* bpp: 0x33 SBUS level 2 BPP parallel port device
* DBRI: 0x39 SBUS level 5 DBRI ISDN audio
* SUNW,leo: 0x39 SBUS level 5 LEO video
* pcmcia: 0x3b SBUS level 6 PCMCIA controller
* uctrl: 0x3b SBUS level 6 UCTRL device
* modem: 0x3d SBUS level 7 MODEM
* zs: 0x2c onboard keyboard/mouse/serial
* floppy: 0x2b onboard Floppy
* power: 0x22 onboard power device (XXX unknown mask bit XXX)
*/
/* Code in entry.S needs to get at these register mappings. */
struct sun4m_irq_percpu __iomem *sun4m_irq_percpu[SUN4M_NCPUS];
struct sun4m_irq_global __iomem *sun4m_irq_global;
struct sun4m_handler_data {
bool percpu;
long mask;
};
/* Dave Redman (djhr@tadpole.co.uk)
* The sun4m interrupt registers.
*/
#define SUN4M_INT_ENABLE 0x80000000
#define SUN4M_INT_E14 0x00000080
#define SUN4M_INT_E10 0x00080000
#define SUN4M_INT_MASKALL 0x80000000 /* mask all interrupts */
#define SUN4M_INT_MODULE_ERR 0x40000000 /* module error */
#define SUN4M_INT_M2S_WRITE_ERR 0x20000000 /* write buffer error */
#define SUN4M_INT_ECC_ERR 0x10000000 /* ecc memory error */
#define SUN4M_INT_VME_ERR 0x08000000 /* vme async error */
#define SUN4M_INT_FLOPPY 0x00400000 /* floppy disk */
#define SUN4M_INT_MODULE 0x00200000 /* module interrupt */
#define SUN4M_INT_VIDEO 0x00100000 /* onboard video */
#define SUN4M_INT_REALTIME 0x00080000 /* system timer */
#define SUN4M_INT_SCSI 0x00040000 /* onboard scsi */
#define SUN4M_INT_AUDIO 0x00020000 /* audio/isdn */
#define SUN4M_INT_ETHERNET 0x00010000 /* onboard ethernet */
#define SUN4M_INT_SERIAL 0x00008000 /* serial ports */
#define SUN4M_INT_KBDMS 0x00004000 /* keyboard/mouse */
#define SUN4M_INT_SBUSBITS 0x00003F80 /* sbus int bits */
#define SUN4M_INT_VMEBITS 0x0000007F /* vme int bits */
#define SUN4M_INT_ERROR (SUN4M_INT_MODULE_ERR | \
SUN4M_INT_M2S_WRITE_ERR | \
SUN4M_INT_ECC_ERR | \
SUN4M_INT_VME_ERR)
#define SUN4M_INT_SBUS(x) (1 << (x+7))
#define SUN4M_INT_VME(x) (1 << (x))
/* Interrupt levels used by OBP */
#define OBP_INT_LEVEL_SOFT 0x10
#define OBP_INT_LEVEL_ONBOARD 0x20
#define OBP_INT_LEVEL_SBUS 0x30
#define OBP_INT_LEVEL_VME 0x40
#define SUN4M_TIMER_IRQ (OBP_INT_LEVEL_ONBOARD | 10)
#define SUN4M_PROFILE_IRQ (OBP_INT_LEVEL_ONBOARD | 14)
static unsigned long sun4m_imask[0x50] = {
/* 0x00 - SMP */
0, SUN4M_SOFT_INT(1),
SUN4M_SOFT_INT(2), SUN4M_SOFT_INT(3),
SUN4M_SOFT_INT(4), SUN4M_SOFT_INT(5),
SUN4M_SOFT_INT(6), SUN4M_SOFT_INT(7),
SUN4M_SOFT_INT(8), SUN4M_SOFT_INT(9),
SUN4M_SOFT_INT(10), SUN4M_SOFT_INT(11),
SUN4M_SOFT_INT(12), SUN4M_SOFT_INT(13),
SUN4M_SOFT_INT(14), SUN4M_SOFT_INT(15),
/* 0x10 - soft */
0, SUN4M_SOFT_INT(1),
SUN4M_SOFT_INT(2), SUN4M_SOFT_INT(3),
SUN4M_SOFT_INT(4), SUN4M_SOFT_INT(5),
SUN4M_SOFT_INT(6), SUN4M_SOFT_INT(7),
SUN4M_SOFT_INT(8), SUN4M_SOFT_INT(9),
SUN4M_SOFT_INT(10), SUN4M_SOFT_INT(11),
SUN4M_SOFT_INT(12), SUN4M_SOFT_INT(13),
SUN4M_SOFT_INT(14), SUN4M_SOFT_INT(15),
/* 0x20 - onboard */
0, 0, 0, 0,
SUN4M_INT_SCSI, 0, SUN4M_INT_ETHERNET, 0,
SUN4M_INT_VIDEO, SUN4M_INT_MODULE,
SUN4M_INT_REALTIME, SUN4M_INT_FLOPPY,
(SUN4M_INT_SERIAL | SUN4M_INT_KBDMS),
SUN4M_INT_AUDIO, SUN4M_INT_E14, SUN4M_INT_MODULE_ERR,
/* 0x30 - sbus */
0, 0, SUN4M_INT_SBUS(0), SUN4M_INT_SBUS(1),
0, SUN4M_INT_SBUS(2), 0, SUN4M_INT_SBUS(3),
0, SUN4M_INT_SBUS(4), 0, SUN4M_INT_SBUS(5),
0, SUN4M_INT_SBUS(6), 0, 0,
/* 0x40 - vme */
0, 0, SUN4M_INT_VME(0), SUN4M_INT_VME(1),
0, SUN4M_INT_VME(2), 0, SUN4M_INT_VME(3),
0, SUN4M_INT_VME(4), 0, SUN4M_INT_VME(5),
0, SUN4M_INT_VME(6), 0, 0
};
static void sun4m_mask_irq(struct irq_data *data)
{
struct sun4m_handler_data *handler_data;
int cpu = smp_processor_id();
handler_data = irq_data_get_irq_handler_data(data);
if (handler_data->mask) {
unsigned long flags;
local_irq_save(flags);
if (handler_data->percpu) {
sbus_writel(handler_data->mask, &sun4m_irq_percpu[cpu]->set);
} else {
sbus_writel(handler_data->mask, &sun4m_irq_global->mask_set);
}
local_irq_restore(flags);
}
}
static void sun4m_unmask_irq(struct irq_data *data)
{
struct sun4m_handler_data *handler_data;
int cpu = smp_processor_id();
handler_data = irq_data_get_irq_handler_data(data);
if (handler_data->mask) {
unsigned long flags;
local_irq_save(flags);
if (handler_data->percpu) {
sbus_writel(handler_data->mask, &sun4m_irq_percpu[cpu]->clear);
} else {
sbus_writel(handler_data->mask, &sun4m_irq_global->mask_clear);
}
local_irq_restore(flags);
}
}
static unsigned int sun4m_startup_irq(struct irq_data *data)
{
irq_link(data->irq);
sun4m_unmask_irq(data);
return 0;
}
static void sun4m_shutdown_irq(struct irq_data *data)
{
sun4m_mask_irq(data);
irq_unlink(data->irq);
}
static struct irq_chip sun4m_irq = {
.name = "sun4m",
.irq_startup = sun4m_startup_irq,
.irq_shutdown = sun4m_shutdown_irq,
.irq_mask = sun4m_mask_irq,
.irq_unmask = sun4m_unmask_irq,
};
static unsigned int sun4m_build_device_irq(struct platform_device *op,
unsigned int real_irq)
{
struct sun4m_handler_data *handler_data;
unsigned int irq;
unsigned int pil;
if (real_irq >= OBP_INT_LEVEL_VME) {
prom_printf("Bogus sun4m IRQ %u\n", real_irq);
prom_halt();
}
pil = (real_irq & 0xf);
irq = irq_alloc(real_irq, pil);
if (irq == 0)
goto out;
handler_data = irq_get_handler_data(irq);
if (unlikely(handler_data))
goto out;
handler_data = kzalloc(sizeof(struct sun4m_handler_data), GFP_ATOMIC);
if (unlikely(!handler_data)) {
prom_printf("IRQ: kzalloc(sun4m_handler_data) failed.\n");
prom_halt();
}
handler_data->mask = sun4m_imask[real_irq];
handler_data->percpu = real_irq < OBP_INT_LEVEL_ONBOARD;
irq_set_chip_and_handler_name(irq, &sun4m_irq,
handle_level_irq, "level");
irq_set_handler_data(irq, handler_data);
out:
return irq;
}
struct sun4m_timer_percpu {
u32 l14_limit;
u32 l14_count;
u32 l14_limit_noclear;
u32 user_timer_start_stop;
};
static struct sun4m_timer_percpu __iomem *timers_percpu[SUN4M_NCPUS];
struct sun4m_timer_global {
u32 l10_limit;
u32 l10_count;
u32 l10_limit_noclear;
u32 reserved;
u32 timer_config;
};
static struct sun4m_timer_global __iomem *timers_global;
static void sun4m_clear_clock_irq(void)
{
sbus_readl(&timers_global->l10_limit);
}
void sun4m_nmi(struct pt_regs *regs)
{
unsigned long afsr, afar, si;
printk(KERN_ERR "Aieee: sun4m NMI received!\n");
/* XXX HyperSparc hack XXX */
__asm__ __volatile__("mov 0x500, %%g1\n\t"
"lda [%%g1] 0x4, %0\n\t"
"mov 0x600, %%g1\n\t"
"lda [%%g1] 0x4, %1\n\t" :
"=r" (afsr), "=r" (afar));
printk(KERN_ERR "afsr=%08lx afar=%08lx\n", afsr, afar);
si = sbus_readl(&sun4m_irq_global->pending);
printk(KERN_ERR "si=%08lx\n", si);
if (si & SUN4M_INT_MODULE_ERR)
printk(KERN_ERR "Module async error\n");
if (si & SUN4M_INT_M2S_WRITE_ERR)
printk(KERN_ERR "MBus/SBus async error\n");
if (si & SUN4M_INT_ECC_ERR)
printk(KERN_ERR "ECC memory error\n");
if (si & SUN4M_INT_VME_ERR)
printk(KERN_ERR "VME async error\n");
printk(KERN_ERR "you lose buddy boy...\n");
show_regs(regs);
prom_halt();
}
void sun4m_unmask_profile_irq(void)
{
unsigned long flags;
local_irq_save(flags);
sbus_writel(sun4m_imask[SUN4M_PROFILE_IRQ], &sun4m_irq_global->mask_clear);
local_irq_restore(flags);
}
void sun4m_clear_profile_irq(int cpu)
{
sbus_readl(&timers_percpu[cpu]->l14_limit);
}
static void sun4m_load_profile_irq(int cpu, unsigned int limit)
{
unsigned int value = limit ? timer_value(limit) : 0;
sbus_writel(value, &timers_percpu[cpu]->l14_limit);
}
static void __init sun4m_init_timers(void)
{
struct device_node *dp = of_find_node_by_name(NULL, "counter");
int i, err, len, num_cpu_timers;
unsigned int irq;
const u32 *addr;
if (!dp) {
printk(KERN_ERR "sun4m_init_timers: No 'counter' node.\n");
return;
}
addr = of_get_property(dp, "address", &len);
of_node_put(dp);
if (!addr) {
printk(KERN_ERR "sun4m_init_timers: No 'address' prop.\n");
return;
}
num_cpu_timers = (len / sizeof(u32)) - 1;
for (i = 0; i < num_cpu_timers; i++) {
timers_percpu[i] = (void __iomem *)
(unsigned long) addr[i];
}
timers_global = (void __iomem *)
(unsigned long) addr[num_cpu_timers];
/* Every per-cpu timer works in timer mode */
sbus_writel(0x00000000, &timers_global->timer_config);
#ifdef CONFIG_SMP
sparc_config.cs_period = SBUS_CLOCK_RATE * 2; /* 2 seconds */
sparc_config.features |= FEAT_L14_ONESHOT;
#else
sparc_config.cs_period = SBUS_CLOCK_RATE / HZ; /* 1/HZ sec */
sparc_config.features |= FEAT_L10_CLOCKEVENT;
#endif
sparc_config.features |= FEAT_L10_CLOCKSOURCE;
sbus_writel(timer_value(sparc_config.cs_period),
&timers_global->l10_limit);
master_l10_counter = &timers_global->l10_count;
irq = sun4m_build_device_irq(NULL, SUN4M_TIMER_IRQ);
err = request_irq(irq, timer_interrupt, IRQF_TIMER, "timer", NULL);
if (err) {
printk(KERN_ERR "sun4m_init_timers: Register IRQ error %d.\n",
err);
return;
}
for (i = 0; i < num_cpu_timers; i++)
sbus_writel(0, &timers_percpu[i]->l14_limit);
if (num_cpu_timers == 4)
sbus_writel(SUN4M_INT_E14, &sun4m_irq_global->mask_set);
#ifdef CONFIG_SMP
{
unsigned long flags;
struct tt_entry *trap_table = &sparc_ttable[SP_TRAP_IRQ1 + (14 - 1)];
/* For SMP we use the level 14 ticker, however the bootup code
* has copied the firmware's level 14 vector into the boot cpu's
* trap table, we must fix this now or we get squashed.
*/
local_irq_save(flags);
trap_table->inst_one = lvl14_save[0];
trap_table->inst_two = lvl14_save[1];
trap_table->inst_three = lvl14_save[2];
trap_table->inst_four = lvl14_save[3];
local_ops->cache_all();
local_irq_restore(flags);
}
#endif
}
void __init sun4m_init_IRQ(void)
{
struct device_node *dp = of_find_node_by_name(NULL, "interrupt");
int len, i, mid, num_cpu_iregs;
const u32 *addr;
if (!dp) {
printk(KERN_ERR "sun4m_init_IRQ: No 'interrupt' node.\n");
return;
}
addr = of_get_property(dp, "address", &len);
of_node_put(dp);
if (!addr) {
printk(KERN_ERR "sun4m_init_IRQ: No 'address' prop.\n");
return;
}
num_cpu_iregs = (len / sizeof(u32)) - 1;
for (i = 0; i < num_cpu_iregs; i++) {
sun4m_irq_percpu[i] = (void __iomem *)
(unsigned long) addr[i];
}
sun4m_irq_global = (void __iomem *)
(unsigned long) addr[num_cpu_iregs];
local_irq_disable();
sbus_writel(~SUN4M_INT_MASKALL, &sun4m_irq_global->mask_set);
for (i = 0; !cpu_find_by_instance(i, NULL, &mid); i++)
sbus_writel(~0x17fff, &sun4m_irq_percpu[mid]->clear);
if (num_cpu_iregs == 4)
sbus_writel(0, &sun4m_irq_global->interrupt_target);
sparc_config.init_timers = sun4m_init_timers;
sparc_config.build_device_irq = sun4m_build_device_irq;
sparc_config.clock_rate = SBUS_CLOCK_RATE;
sparc_config.clear_clock_irq = sun4m_clear_clock_irq;
sparc_config.load_profile_irq = sun4m_load_profile_irq;
/* Cannot enable interrupts until OBP ticker is disabled. */
}