linux/arch/s390/lib/delay.c

132 lines
2.8 KiB
C
Raw Normal View History

/*
* Precise Delay Loops for S390
*
* Copyright IBM Corp. 1999, 2008
* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
* Heiko Carstens <heiko.carstens@de.ibm.com>,
*/
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/timex.h>
#include <linux/module.h>
#include <linux/irqflags.h>
#include <linux/interrupt.h>
#include <asm/div64.h>
#include <asm/timer.h>
void __delay(unsigned long loops)
{
/*
* To end the bloody studid and useless discussion about the
* BogoMips number I took the liberty to define the __delay
* function in a way that that resulting BogoMips number will
* yield the megahertz number of the cpu. The important function
* is udelay and that is done using the tod clock. -- martin.
*/
asm volatile("0: brct %0,0b" : : "d" ((loops/2) + 1));
}
static void __udelay_disabled(unsigned long long usecs)
{
unsigned long cr0, cr6, new;
u64 clock_saved, end;
end = get_clock() + (usecs << 12);
clock_saved = local_tick_disable();
__ctl_store(cr0, 0, 0);
__ctl_store(cr6, 6, 6);
new = (cr0 & 0xffff00e0) | 0x00000800;
__ctl_load(new , 0, 0);
new = 0;
__ctl_load(new, 6, 6);
[S390] udelay: disable lockdep to avoid false positives Our udelay implementation enables interrupts to receive a special timer interrupt regardless of the context it is called from. This might lead to false positive lockdep reports. Since lockdep isn't aware of the fact that only a single interrupt source is enabled it warns about possible deadlocks that in reality won't happen, like the one below. To fix this disable lockdep before enabling interrupts. [ 254.040888] ================================= [ 254.040904] [ INFO: inconsistent lock state ] [ 254.040910] 2.6.30 #9 [ 254.040914] --------------------------------- [ 254.040920] inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage. [ 254.040927] swapper/0 [HC0[0]:SC1[1]:HE1:SE0] takes: [ 254.040934] (sch->lock){?.-...}, at: [<00000000002e4778>] ccw_device_timeout+0x48/0x2f0 [ 254.040961] {IN-HARDIRQ-W} state was registered at: [ 254.040969] [<0000000000096f74>] __lock_acquire+0x9d4/0x188c [ 254.040985] [<0000000000097f68>] lock_acquire+0x13c/0x16c [ 254.040998] [<00000000004527e0>] _spin_lock+0x74/0xb8 [ 254.041016] [<0000000000457eb2>] do_IRQ+0xde/0x208 [ 254.041031] [<000000000002d190>] io_return+0x0/0x8 [ 254.041049] [<0000000000029faa>] vtime_stop_cpu+0xbe/0x114 [ 254.041066] irq event stamp: 259629 [ 254.041076] hardirqs last enabled at (259628): [<000000000045238e>] _spin_unlock_irq+0x5e/0x9c [ 254.041095] hardirqs last disabled at (259629): [<000000000045292e>] _spin_lock_irq+0x4a/0xc4 [ 254.041126] softirqs last enabled at (259614): [<000000000006500e>] __do_softirq+0x296/0x2b0 [ 254.041137] softirqs last disabled at (259619): [<0000000000024cf6>] do_softirq+0x102/0x108 [ 254.041147] [ 254.041148] other info that might help us debug this: [ 254.041153] 2 locks held by swapper/0: [ 254.041157] #0: (&priv->timer){+.-...}, at: [<000000000006bf9a>] run_timer_softirq+0x19a/0x340 [ 254.041170] #1: (sch->lock){?.-...}, at: [<00000000002e4778>] ccw_device_timeout+0x48/0x2f0 [ 254.041182] [ 254.041310] Call Trace: [ 254.041313] ([<00000000000174fc>] show_trace+0x16c/0x170) [ 254.041321] [<0000000000017578>] show_stack+0x78/0x104 [ 254.041327] [<000000000044d0ca>] dump_stack+0xc6/0xd4 [ 254.041342] [<00000000000949b4>] print_usage_bug+0x1c8/0x1fc [ 254.041353] [<0000000000094e8a>] mark_lock+0x4a2/0x670 [ 254.041364] [<00000000000950e2>] mark_held_locks+0x8a/0xb4 [ 254.041375] [<0000000000095398>] trace_hardirqs_on_caller+0x74/0x1ac [ 254.041388] [<00000000000954fa>] trace_hardirqs_on+0x2a/0x38 [ 254.041402] [<000000000025f1ec>] __udelay_disabled+0xac/0xfc [ 254.041419] [<000000000025f432>] __udelay+0x12a/0x148 [ 254.041433] [<00000000002d64d8>] cio_commit_config+0x170/0x290 [ 254.041451] [<00000000002d6978>] cio_disable_subchannel+0x120/0x1cc [ 254.041468] [<00000000002e32a4>] ccw_device_recog_done+0x54/0x2f4 [ 254.041485] [<00000000002e3638>] ccw_device_sense_id_done+0x50/0x90 [ 254.041508] [<00000000002e615a>] snsid_callback+0xfa/0x3a8 [ 254.041515] [<00000000002dd96c>] ccwreq_stop+0x80/0x90 [ 254.041523] [<00000000002dda8e>] ccw_request_timeout+0xc2/0xd0 [ 254.041530] [<00000000002e2f70>] ccw_device_request_event+0x58/0x90 [ 254.041537] [<00000000002e47ae>] ccw_device_timeout+0x7e/0x2f0 [ 254.041555] [<000000000006c02a>] run_timer_softirq+0x22a/0x340 [ 254.041566] [<0000000000064eb0>] __do_softirq+0x138/0x2b0 [ 254.041578] [<0000000000024cf6>] do_softirq+0x102/0x108 [ 254.041590] [<00000000000647ce>] irq_exit+0xee/0x114 [ 254.041603] [<0000000000457d88>] do_extint+0x130/0x17c [ 254.041617] [<000000000002d41e>] ext_no_vtime+0x1e/0x22 [ 254.041631] [<0000000000029faa>] vtime_stop_cpu+0xbe/0x114 [ 254.041646] ([<0000000000029f58>] vtime_stop_cpu+0x6c/0x114) [ 254.041662] [<000000000001d842>] cpu_idle+0x122/0x1c0 [ 254.041679] [<00000000004482c6>] start_secondary+0xce/0xe0 [ 254.041696] [<0000000000000000>] 0x0 [ 254.041715] [<0000000000000000>] 0x0 [ 254.041745] INFO: lockdep is turned off. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2009-07-07 22:37:05 +08:00
lockdep_off();
do {
set_clock_comparator(end);
vtime_stop_cpu();
local_irq_disable();
} while (get_clock() < end);
[S390] udelay: disable lockdep to avoid false positives Our udelay implementation enables interrupts to receive a special timer interrupt regardless of the context it is called from. This might lead to false positive lockdep reports. Since lockdep isn't aware of the fact that only a single interrupt source is enabled it warns about possible deadlocks that in reality won't happen, like the one below. To fix this disable lockdep before enabling interrupts. [ 254.040888] ================================= [ 254.040904] [ INFO: inconsistent lock state ] [ 254.040910] 2.6.30 #9 [ 254.040914] --------------------------------- [ 254.040920] inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage. [ 254.040927] swapper/0 [HC0[0]:SC1[1]:HE1:SE0] takes: [ 254.040934] (sch->lock){?.-...}, at: [<00000000002e4778>] ccw_device_timeout+0x48/0x2f0 [ 254.040961] {IN-HARDIRQ-W} state was registered at: [ 254.040969] [<0000000000096f74>] __lock_acquire+0x9d4/0x188c [ 254.040985] [<0000000000097f68>] lock_acquire+0x13c/0x16c [ 254.040998] [<00000000004527e0>] _spin_lock+0x74/0xb8 [ 254.041016] [<0000000000457eb2>] do_IRQ+0xde/0x208 [ 254.041031] [<000000000002d190>] io_return+0x0/0x8 [ 254.041049] [<0000000000029faa>] vtime_stop_cpu+0xbe/0x114 [ 254.041066] irq event stamp: 259629 [ 254.041076] hardirqs last enabled at (259628): [<000000000045238e>] _spin_unlock_irq+0x5e/0x9c [ 254.041095] hardirqs last disabled at (259629): [<000000000045292e>] _spin_lock_irq+0x4a/0xc4 [ 254.041126] softirqs last enabled at (259614): [<000000000006500e>] __do_softirq+0x296/0x2b0 [ 254.041137] softirqs last disabled at (259619): [<0000000000024cf6>] do_softirq+0x102/0x108 [ 254.041147] [ 254.041148] other info that might help us debug this: [ 254.041153] 2 locks held by swapper/0: [ 254.041157] #0: (&priv->timer){+.-...}, at: [<000000000006bf9a>] run_timer_softirq+0x19a/0x340 [ 254.041170] #1: (sch->lock){?.-...}, at: [<00000000002e4778>] ccw_device_timeout+0x48/0x2f0 [ 254.041182] [ 254.041310] Call Trace: [ 254.041313] ([<00000000000174fc>] show_trace+0x16c/0x170) [ 254.041321] [<0000000000017578>] show_stack+0x78/0x104 [ 254.041327] [<000000000044d0ca>] dump_stack+0xc6/0xd4 [ 254.041342] [<00000000000949b4>] print_usage_bug+0x1c8/0x1fc [ 254.041353] [<0000000000094e8a>] mark_lock+0x4a2/0x670 [ 254.041364] [<00000000000950e2>] mark_held_locks+0x8a/0xb4 [ 254.041375] [<0000000000095398>] trace_hardirqs_on_caller+0x74/0x1ac [ 254.041388] [<00000000000954fa>] trace_hardirqs_on+0x2a/0x38 [ 254.041402] [<000000000025f1ec>] __udelay_disabled+0xac/0xfc [ 254.041419] [<000000000025f432>] __udelay+0x12a/0x148 [ 254.041433] [<00000000002d64d8>] cio_commit_config+0x170/0x290 [ 254.041451] [<00000000002d6978>] cio_disable_subchannel+0x120/0x1cc [ 254.041468] [<00000000002e32a4>] ccw_device_recog_done+0x54/0x2f4 [ 254.041485] [<00000000002e3638>] ccw_device_sense_id_done+0x50/0x90 [ 254.041508] [<00000000002e615a>] snsid_callback+0xfa/0x3a8 [ 254.041515] [<00000000002dd96c>] ccwreq_stop+0x80/0x90 [ 254.041523] [<00000000002dda8e>] ccw_request_timeout+0xc2/0xd0 [ 254.041530] [<00000000002e2f70>] ccw_device_request_event+0x58/0x90 [ 254.041537] [<00000000002e47ae>] ccw_device_timeout+0x7e/0x2f0 [ 254.041555] [<000000000006c02a>] run_timer_softirq+0x22a/0x340 [ 254.041566] [<0000000000064eb0>] __do_softirq+0x138/0x2b0 [ 254.041578] [<0000000000024cf6>] do_softirq+0x102/0x108 [ 254.041590] [<00000000000647ce>] irq_exit+0xee/0x114 [ 254.041603] [<0000000000457d88>] do_extint+0x130/0x17c [ 254.041617] [<000000000002d41e>] ext_no_vtime+0x1e/0x22 [ 254.041631] [<0000000000029faa>] vtime_stop_cpu+0xbe/0x114 [ 254.041646] ([<0000000000029f58>] vtime_stop_cpu+0x6c/0x114) [ 254.041662] [<000000000001d842>] cpu_idle+0x122/0x1c0 [ 254.041679] [<00000000004482c6>] start_secondary+0xce/0xe0 [ 254.041696] [<0000000000000000>] 0x0 [ 254.041715] [<0000000000000000>] 0x0 [ 254.041745] INFO: lockdep is turned off. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2009-07-07 22:37:05 +08:00
lockdep_on();
__ctl_load(cr0, 0, 0);
__ctl_load(cr6, 6, 6);
local_tick_enable(clock_saved);
}
static void __udelay_enabled(unsigned long long usecs)
{
u64 clock_saved, end;
end = get_clock() + (usecs << 12);
do {
clock_saved = 0;
if (end < S390_lowcore.clock_comparator) {
clock_saved = local_tick_disable();
set_clock_comparator(end);
}
vtime_stop_cpu();
local_irq_disable();
if (clock_saved)
local_tick_enable(clock_saved);
} while (get_clock() < end);
}
/*
* Waits for 'usecs' microseconds using the TOD clock comparator.
*/
void __udelay(unsigned long long usecs)
{
unsigned long flags;
preempt_disable();
local_irq_save(flags);
if (in_irq()) {
__udelay_disabled(usecs);
goto out;
}
if (in_softirq()) {
if (raw_irqs_disabled_flags(flags))
__udelay_disabled(usecs);
else
__udelay_enabled(usecs);
goto out;
}
if (raw_irqs_disabled_flags(flags)) {
local_bh_disable();
__udelay_disabled(usecs);
_local_bh_enable();
goto out;
}
__udelay_enabled(usecs);
out:
local_irq_restore(flags);
preempt_enable();
}
EXPORT_SYMBOL(__udelay);
/*
* Simple udelay variant. To be used on startup and reboot
* when the interrupt handler isn't working.
*/
void udelay_simple(unsigned long long usecs)
{
u64 end;
end = get_clock() + (usecs << 12);
while (get_clock() < end)
cpu_relax();
}
void __ndelay(unsigned long long nsecs)
{
u64 end;
nsecs <<= 9;
do_div(nsecs, 125);
end = get_clock() + nsecs;
if (nsecs & ~0xfffUL)
__udelay(nsecs >> 12);
while (get_clock() < end)
barrier();
}
EXPORT_SYMBOL(__ndelay);