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path: root/arch/avr32/kernel/process.c
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2008-08-05avr32: Use <mach/foo.h> instead of <asm/arch/foo.h>Haavard Skinnemoen
Update all avr32-specific files to use the new platform-specific header locations. Drivers shared with ARM are left alone for now. Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
2008-07-18nohz: prevent tick stop outside of the idle loopThomas Gleixner
Jack Ren and Eric Miao tracked down the following long standing problem in the NOHZ code: scheduler switch to idle task enable interrupts Window starts here ----> interrupt happens (does not set NEED_RESCHED) irq_exit() stops the tick ----> interrupt happens (does set NEED_RESCHED) return from schedule() cpu_idle(): preempt_disable(); Window ends here The interrupts can happen at any point inside the race window. The first interrupt stops the tick, the second one causes the scheduler to rerun and switch away from idle again and we end up with the tick disabled. The fact that it needs two interrupts where the first one does not set NEED_RESCHED and the second one does made the bug obscure and extremly hard to reproduce and analyse. Kudos to Jack and Eric. Solution: Limit the NOHZ functionality to the idle loop to make sure that we can not run into such a situation ever again. cpu_idle() { preempt_disable(); while(1) { tick_nohz_stop_sched_tick(1); <- tell NOHZ code that we are in the idle loop while (!need_resched()) halt(); tick_nohz_restart_sched_tick(); <- disables NOHZ mode preempt_enable_no_resched(); schedule(); preempt_disable(); } } In hindsight we should have done this forever, but ... /me grabs a large brown paperbag. Debugged-by: Jack Ren <jack.ren@marvell.com>, Debugged-by: eric miao <eric.y.miao@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-04-19avr32: Add hardware power-down function callPeter Ma
This patch adds in the indirect call to pm_power_off(), as is done in other architectures (e.g. ARM). Tested on NGW100, with custom board with GPIO control over main DC power. Signed-off-by: Peter Ma <pma@mediamatech.com> Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
2008-04-19avr32: Move sleep code into mach-at32apHaavard Skinnemoen
Create a new file, pm-at32ap700x.S, in mach-at32ap and move the CPU idle sleep code there. Make it possible to disable the sleep code. Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
2008-02-27avr32: Fix OCD refcounting bugHaavard Skinnemoen
Iff the parent has TIF_DEBUG set, _and_ clone_flags includes CLONE_PTRACE we should set the TIF_DEBUG flag for the child and increment the ocd refcount. Otherwise, the TIF_DEBUG flag must be unset. Currently, the child inherits TIF_DEBUG from the parent before copy_thread is called, so TIF_DEBUG may be already be set before we determine whether the child is supposed to inherit debugging capabilities from the parent or not. This means that ocd_enable() won't increment the refcount, because TIF_DEBUG is already set, and that TIF_DEBUG will be set for processes that aren't being debugged. This leads to a refcounting asymmetry, which may show up as ------------[ cut here ]------------ Badness at arch/avr32/kernel/ocd.c:73 PC is at ocd_disable+0x34/0x60 LR is at put_lock_stats+0xa/0x20 as reported by David Brownell. Happens when strace'ing a process that forks a new child process, e.g. "strace mount -tjffs2 mtd1 /mnt", and subsequently killing the child process (e.g. "umount /mnt".) Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
2008-02-15avr32: Call tick_nohz_{stop,restart}_sched_tick() in idle loopHaavard Skinnemoen
This fixes a hang on boot with nohz enabled. nohz is not actually supported in mainline yet, but patches that add support for it are currently under review. When nohz is compiled out, the functions are no-ops, so this patch results in no functional change, but it arguably makes the code more correct. Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
2008-01-25[AVR32] Enable debugging only when neededHaavard Skinnemoen
Keep track of processes being debugged (including the kernel itself) and turn the OCD system on and off as appropriate. Since enabling debugging turns off some optimizations in the CPU core, this fixes the issue that enabling KProbes support or simply running a program under gdbserver will reduce system performance significantly until the next reboot. The CPU performance will still be reduced for all processes while a process is being debugged, but this is a lot better than reducing the performance forever. Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
2007-12-07[AVR32] Clean up OCD register usageHaavard Skinnemoen
Generate a new set of OCD register definitions in asm/ocd.h and rename __mfdr() and __mtdr() to ocd_read() and ocd_write() respectively. The bitfield definitions are a lot more complete now, and they are entirely based on bit numbers, not masks. This is because OCD registers are frequently accessed from assembly code, where bit numbers are a lot more useful (can be fed directly to sbr, bfins, etc.) Bitfields that consist of more than one bit have two definitions: _START, which indicates the number of the first bit, and _SIZE, which indicates the number of bits. These directly correspond to the parameters taken by the bfextu, bfexts and bfins instructions. Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
2007-12-07[AVR32] Fix invalid status register bit definitions in asm/ptrace.hHaavard Skinnemoen
The 'H' bit is bit 29, while the 'R' bit doesn't exist. Luckily, we don't actually use any of the bits in question. Also update show_regs() to show the Debug Mask and Debug state bits. Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
2007-05-09wrap access to thread_infoRoman Zippel
Recently a few direct accesses to the thread_info in the task structure snuck back, so this wraps them with the appropriate wrapper. Signed-off-by: Roman Zippel <zippel@linux-m68k.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-04-27[AVR32] Clean up exception handling codeHaavard Skinnemoen
* Use generic BUG() handling * Remove some useless debug statements * Use a common function _exception() to send signals or oops when an exception can't be handled. This makes sure init doesn't enter an infinite exception loop as well. Borrowed from powerpc. * Add some basic exception tracing support to the page fault code. * Rework dump_stack(), show_regs() and friends and move everything into process.c * Print information about configuration options and chip type when oopsing Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
2007-04-27[AVR32] Put cpu in sleep 0 when idle.Hans-Christian Egtvedt
This patch puts the CPU in sleep 0 when doing nothing, idle. This will turn of the CPU clock and thus save power. The CPU is waken again when an interrupt occurs. Signed-off-by: Hans-Christian Egtvedt <hcegtvedt@atmel.com> Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
2006-12-08[AVR32] Put the chip in "stop" mode when halting the systemHaavard Skinnemoen
Make machine_halt() execute a sleep instruction to put the chip in "stop" mode when the system is halted. This switches off all clocks except the 32 kHz oscillator, which is needed for the RTC to keep ticking. Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
2006-09-26[PATCH] avr32 architectureHaavard Skinnemoen
This adds support for the Atmel AVR32 architecture as well as the AT32AP7000 CPU and the AT32STK1000 development board. AVR32 is a new high-performance 32-bit RISC microprocessor core, designed for cost-sensitive embedded applications, with particular emphasis on low power consumption and high code density. The AVR32 architecture is not binary compatible with earlier 8-bit AVR architectures. The AVR32 architecture, including the instruction set, is described by the AVR32 Architecture Manual, available from http://www.atmel.com/dyn/resources/prod_documents/doc32000.pdf The Atmel AT32AP7000 is the first CPU implementing the AVR32 architecture. It features a 7-stage pipeline, 16KB instruction and data caches and a full Memory Management Unit. It also comes with a large set of integrated peripherals, many of which are shared with the AT91 ARM-based controllers from Atmel. Full data sheet is available from http://www.atmel.com/dyn/resources/prod_documents/doc32003.pdf while the CPU core implementation including caches and MMU is documented by the AVR32 AP Technical Reference, available from http://www.atmel.com/dyn/resources/prod_documents/doc32001.pdf Information about the AT32STK1000 development board can be found at http://www.atmel.com/dyn/products/tools_card.asp?tool_id=3918 including a BSP CD image with an earlier version of this patch, development tools (binaries and source/patches) and a root filesystem image suitable for booting from SD card. Alternatively, there's a preliminary "getting started" guide available at http://avr32linux.org/twiki/bin/view/Main/GettingStarted which provides links to the sources and patches you will need in order to set up a cross-compiling environment for avr32-linux. This patch, as well as the other patches included with the BSP and the toolchain patches, is actively supported by Atmel Corporation. [dmccr@us.ibm.com: Fix more pxx_page macro locations] [bunk@stusta.de: fix `make defconfig'] Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com> Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Dave McCracken <dmccr@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>