Maintain a per-CPU global "struct pt_regs *" variable which can be used instead
of passing regs around manually through all ~1800 interrupt handlers in the
Linux kernel.
The regs pointer is used in few places, but it potentially costs both stack
space and code to pass it around. On the FRV arch, removing the regs parameter
from all the genirq function results in a 20% speed up of the IRQ exit path
(ie: from leaving timer_interrupt() to leaving do_IRQ()).
Where appropriate, an arch may override the generic storage facility and do
something different with the variable. On FRV, for instance, the address is
maintained in GR28 at all times inside the kernel as part of general exception
handling.
Having looked over the code, it appears that the parameter may be handed down
through up to twenty or so layers of functions. Consider a USB character
device attached to a USB hub, attached to a USB controller that posts its
interrupts through a cascaded auxiliary interrupt controller. A character
device driver may want to pass regs to the sysrq handler through the input
layer which adds another few layers of parameter passing.
I've build this code with allyesconfig for x86_64 and i386. I've runtested the
main part of the code on FRV and i386, though I can't test most of the drivers.
I've also done partial conversion for powerpc and MIPS - these at least compile
with minimal configurations.
This will affect all archs. Mostly the changes should be relatively easy.
Take do_IRQ(), store the regs pointer at the beginning, saving the old one:
struct pt_regs *old_regs = set_irq_regs(regs);
And put the old one back at the end:
set_irq_regs(old_regs);
Don't pass regs through to generic_handle_irq() or __do_IRQ().
In timer_interrupt(), this sort of change will be necessary:
- update_process_times(user_mode(regs));
- profile_tick(CPU_PROFILING, regs);
+ update_process_times(user_mode(get_irq_regs()));
+ profile_tick(CPU_PROFILING);
I'd like to move update_process_times()'s use of get_irq_regs() into itself,
except that i386, alone of the archs, uses something other than user_mode().
Some notes on the interrupt handling in the drivers:
(*) input_dev() is now gone entirely. The regs pointer is no longer stored in
the input_dev struct.
(*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does
something different depending on whether it's been supplied with a regs
pointer or not.
(*) Various IRQ handler function pointers have been moved to type
irq_handler_t.
Signed-Off-By: David Howells <dhowells@redhat.com>
(cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
This is more preparation for adding support for the new Atmel AT91SAM9
processors.
Changes include:
- Replace AT91_BASE_* with AT91RM9200_BASE_*
- Replace AT91_ID_* with AT91RM9200_ID_*
- ROM, SRAM and UHP address definitions moved to at91rm9200.h.
- The raw AT91_P[ABCD]_* definitions are now depreciated in favour of
the GPIO API.
Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Making structs const prevents accidental bugs and with the proper debug
options they're protected against corruption.
Signed-off-by: Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
UDC updates for AT91 series processors:
- Get ready for at91sam926x processors (ARMv5tej not ARMv4t)
- Suspend/resume support now behaves properly
- In "standby" mode, UDC can be a source of system wakeup events
(host resume, device connect/disconnect, etc)
- Fix IRQ storming issues, seemingly related to clock disabling
changes that went in a while back
And minor cleanups, especially whitespace.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
AT91: the two USB drivers (OHCI, UDC) got out of sync with various
usbcore and driver model PM updates; fix.
Also minor fixes to ohci: whitespace/style, MODULE_ALIAS so coldplug works
using /sys/.../modalias, and turn off _both_ clocks during suspend.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This adds support for the USB peripheral controller on AT91
(rm9200, eventually also sam9261 or uClinux) platforms.
More SOC support for Linux-USB ... an uncomplicated pure PIO driver.
It'd be worth using this as a model, if you're starting a driver
for some other peripheral controller.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
