The tick_nohz_stop_sched_tick() function, which tries to delay
the next timer tick as long as possible, can be called from two
places:
- From the idle loop to start the dytick idle mode
- From interrupt exit if we have interrupted the dyntick
idle mode, so that we reprogram the next tick event in
case the irq changed some internal state that requires this
action.
There are only few minor differences between both that
are handled by that function, driven by the ts->inidle
cpu variable and the inidle parameter. The whole guarantees
that we only update the dyntick mode on irq exit if we actually
interrupted the dyntick idle mode, and that we enter in RCU extended
quiescent state from idle loop entry only.
Split this function into:
- tick_nohz_idle_enter(), which sets ts->inidle to 1, enters
dynticks idle mode unconditionally if it can, and enters into RCU
extended quiescent state.
- tick_nohz_irq_exit() which only updates the dynticks idle mode
when ts->inidle is set (ie: if tick_nohz_idle_enter() has been called).
To maintain symmetry, tick_nohz_restart_sched_tick() has been renamed
into tick_nohz_idle_exit().
This simplifies the code and micro-optimize the irq exit path (no need
for local_irq_save there). This also prepares for the split between
dynticks and rcu extended quiescent state logics. We'll need this split to
further fix illegal uses of RCU in extended quiescent states in the idle
loop.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: David Miller <davem@davemloft.net>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
For the initial architecture submission, not all of the DMA ops were
implemented. This patch adds the *map_page and *map_sg variants of the
DMA mapping ops.
This patch is currently of interest mainly to some drivers that haven't
been submitted upstream yet.
Signed-off-by: Jonas Bonn <jonas@southpole.se>
As it was decided not to export struct pt_regs to userspace, struct
sigcontext shouldn't be using it either. The pt_regs struct for OpenRISC
is kernel internal and the layout of the registers may change in the
future. The struct user_regs_struct is what is guaranteed to remain
stable, so struct sigcontext may use that instead.
This patch removes the usage of struct pt_regs in struct sigcontext and
makes according changes in signal.c to get the register layout right.
The usp field is removed from the sigcontext structure as this information
is already contained in the user_regs_struct.
Signed-off-by: Jonas Bonn <jonas@southpole.se>
Reviewed-by: Emilio Cota <cota@braap.org>
Adds README file, TODO list, and a couple of other pieces that didn't seem
to fit into any other patch.
Signed-off-by: Jonas Bonn <jonas@southpole.se>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
The OpenRISC Linux kernel conforms to the "generic" syscall interface which
contains only the reduced set of syscalls deemed necessary for new
architectures. Unfortunately, the uClibc port for OpenRISC does not fully
support this reduced set; as such, an additional patch available out-of-tree
needs to be applied to the kernel in order to use the current uClibc. This
is just a temporary measure until the libc port can be straightened out; it
is likely that OpenRISC will make the transition to glibc shortly where the
generic syscall interface is better supported.
Signed-off-by: Jonas Bonn <jonas@southpole.se>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
This patch adds support for the OpenRISC PIC.
Signed-off-by: Jonas Bonn <jonas@southpole.se>
Cc: tglx@linutronix.de
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Implements support for the OpenRISC timer which is a 28 bit cycle counter
that can be read out of a special purpose register. This counter is
used as a both a clock event and clocksource device.
Signed-off-by: Jonas Bonn <jonas@southpole.se>
Cc: tglx@linutronix.de
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
This patch implements minimal PTrace support. The pt_regs structure is
not exported to userspace for OpenRISC; rather, the GETREGSET mechanism
is intended to be used and the registers, as such, exported in the core
dump format which is ABI stable. This is in line with what is intended
for new architectures as of 2.6.34 and has the advantage of permitting
the layout of the registers on the kernel stack (as per pt_regs) to be
freely modified.
Signed-off-by: Jonas Bonn <jonas@southpole.se>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
The OpenRISC architecture uses the device tree infrastructure for the
platform description. This is currently limited to having a device tree
built into the kernel, but work is underway within the OpenRISC project
to define how this device tree blob should be passed into the kernel from
an external resource.
Patch contains a single example DTS file to go with the defconfig for
or1ksim.
Signed-off-by: Jonas Bonn <jonas@southpole.se>
Cc: devicetree-discuss@lists.ozlabs.org
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Architecture code and early setup routines for booting Linux.
Signed-off-by: Jonas Bonn <jonas@southpole.se>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
