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2014-08-31Merge tag 'xtensa-20140830' of git://github.com/czankel/xtensa-linuxLinus Torvalds
Pull Xtensa updates from Chris Zankel: "Xtensa improvements for 3.17: - support highmem on cores with aliasing data cache. Enable highmem on kc705 by default - simplify addition of new core variants (no need to modify Kconfig / Makefiles) - improve robustness of unaligned access handler and its interaction with window overflow/underflow exception handlers - deprecate atomic and spill registers syscalls - clean up Kconfig: remove orphan MATH_EMULATION, sort 'select' statements - wire up renameat2 syscall. Various fixes: - fix address checks in dma_{alloc,free}_coherent (runtime BUG) - fix access to THREAD_RA/THREAD_SP/THREAD_DS (debug build breakage) - fix TLBTEMP_BASE_2 region handling in fast_second_level_miss (runtime unrecoverable exception) - fix a6 and a7 handling in fast_syscall_xtensa (runtime userspace register clobbering) - fix kernel/user jump out of fast_unaligned (potential runtime unrecoverabl exception) - replace termios IOCTL code definitions with constants (userspace build breakage)" * tag 'xtensa-20140830' of git://github.com/czankel/xtensa-linux: (25 commits) xtensa: deprecate fast_xtensa and fast_spill_registers syscalls xtensa: don't allow overflow/underflow on unaligned stack xtensa: fix a6 and a7 handling in fast_syscall_xtensa xtensa: allow single-stepping through unaligned load/store xtensa: move invalid unaligned instruction handler closer to its users xtensa: make fast_unaligned store restartable xtensa: add double exception fixup handler for fast_unaligned xtensa: fix kernel/user jump out of fast_unaligned xtensa: configure kc705 for highmem xtensa: support highmem in aliasing cache flushing code xtensa: support aliasing cache in kmap xtensa: support aliasing cache in k[un]map_atomic xtensa: implement clear_user_highpage and copy_user_highpage xtensa: fix TLBTEMP_BASE_2 region handling in fast_second_level_miss xtensa: allow fixmap and kmap span more than one page table xtensa: make fixmap region addressing grow with index xtensa: fix access to THREAD_RA/THREAD_SP/THREAD_DS xtensa: add renameat2 syscall xtensa: fix address checks in dma_{alloc,free}_coherent xtensa: replace IOCTL code definitions with constants ...
2014-08-29flush_icache_range: export symbol to fix build errorsPranith Kumar
Fix building errors occuring due to a missing export of flush_icache_range() in kisskb.ellerman.id.au/kisskb/buildresult/11677809/ ERROR: "flush_icache_range" [drivers/misc/lkdtm.ko] undefined! Signed-off-by: Pranith Kumar <bobby.prani@gmail.com> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> Acked-by: Vineet Gupta <vgupta@synopsys.com> [arc] Acked-by: Richard Kuo <rkuo@codeaurora.org> [hexagon] Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Chris Zankel <chris@zankel.net> Acked-by: Max Filippov <jcmvbkbc@gmail.com> [xtensa] Cc: Noam Camus <noamc@ezchip.com> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Acked-by: Zhigang Lu <zlu@tilera.com> [tile] Cc: Kirill Tkhai <tkhai@yandex.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-08-18Merge tag 'xtensa-for-next-20140815' into for_nextChris Zankel
Xtensa improvements for 3.17: - support highmem on cores with aliasing data cache. Enable highmem on kc705 by default; - simplify addition of new core variants (no need to modify Kconfig / Makefiles); - improve robustness of unaligned access handler and its interaction with window overflow/underflow exception handlers; - deprecate atomic and spill registers syscalls; - clean up Kconfig: remove orphan MATH_EMULATION, sort 'select' statements; - wire up renameat2 syscall. Various fixes: - fix address checks in dma_{alloc,free}_coherent (runtime BUG); - fix access to THREAD_RA/THREAD_SP/THREAD_DS (debug build breakage); - fix TLBTEMP_BASE_2 region handling in fast_second_level_miss (runtime unrecoverable exception); - fix a6 and a7 handling in fast_syscall_xtensa (runtime userspace register clobbering); - fix kernel/user jump out of fast_unaligned (potential runtime unrecoverable exception); - replace termios IOCTL code definitions with constants (userspace build breakage). Signed-off-by: Chris Zankel <chris@zankel.net>
2014-08-14xtensa: deprecate fast_xtensa and fast_spill_registers syscallsMax Filippov
These syscalls are not used by userspace tools for some time now, and they have issues when called with invalid arguments. It's not worth changing signal delivery mechanism as we don't expect any new users for these syscalls. Let's keep them for backwards compatibility under #ifdef, disabled by default. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-08-14xtensa: don't allow overflow/underflow on unaligned stackMax Filippov
Double exceptions that happen during register window overflow/underflow are handled in the topmost stack frame, as if it was the only exception that occured. However unaligned access exception handler is special because it needs to analyze instruction that caused the exception, but the userspace instruction that triggered window exception is completely irrelevant. Unaligned data access is rather normal in the generic userspace code, but stack pointer manipulation must always be done by architecture-aware code and thus unaligned stack means a serious problem anyway. Use the default unaligned access handler that raises SIGBUS in case of unaligned access in window overflow/underflow handler. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-08-14xtensa: fix a6 and a7 handling in fast_syscall_xtensaMax Filippov
Remove restoring a6 on some return paths and instead modify and restore it in a single place, using symbolic name. Correctly restore a7 from PT_AREG7 in case of illegal a6 value. Cc: stable@vger.kernel.org Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-08-14xtensa: allow single-stepping through unaligned load/storeMax Filippov
Update icount when icountlevel is non-zero but not greater than EXCM level when load/store instruction is successfully emulated. This allows single-stepping over such instruction in userspace debugger. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-08-14xtensa: move invalid unaligned instruction handler closer to its usersMax Filippov
With this change a threaded jump from .Linvalid_instruction_load to .Linvalid_instruction can be removed and more code may be added to common load/store exit path. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-08-14xtensa: make fast_unaligned store restartableMax Filippov
fast_unaligned may encounter DTLB miss or SEGFAULT during the store emulation. Don't update epc1 and lcount until after the store emulation is complete, so that the faulting store instruction could be replayed. Remove duplicate code handling zero overhead loops and calculate new epc1 and lcount in one place. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-08-14xtensa: add double exception fixup handler for fast_unalignedMax Filippov
fast_unaligned_fixup restores user registers and runs normal exception handler in the current stack frame. Unaligned load/store is retried after that. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-08-14xtensa: fix kernel/user jump out of fast_unalignedMax Filippov
Use correct register (a0, just read from the PS) to check user mode bit. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-08-14xtensa: fix TLBTEMP_BASE_2 region handling in fast_second_level_missMax Filippov
Current definition of TLBTEMP_BASE_2 is always 32K above the TLBTEMP_BASE_1, whereas fast_second_level_miss handler for the TLBTEMP region analyzes virtual address bit (PAGE_SHIFT + DCACHE_ALIAS_ORDER) to determine TLBTEMP region where the fault happened. The size of the TLBTEMP region is also checked incorrectly: not 64K, but twice data cache way size (whicht may as well be less than the instruction cache way size). Fix TLBTEMP_BASE_2 to be TLBTEMP_BASE_1 + data cache way size. Provide TLBTEMP_SIZE that is a greater of doubled data cache way size or the instruction cache way size, and use it to determine if the second level TLB miss occured in the TLBTEMP region. Practical occurence of page faults in the TLBTEMP area is extremely rare, this code can be tested by deletion of all w[di]tlb instructions in the tlbtemp_mapping region. Cc: stable@vger.kernel.org Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-08-14xtensa: fix access to THREAD_RA/THREAD_SP/THREAD_DSMax Filippov
With SMP and a lot of debug options enabled task_struct::thread gets out of reach of s32i/l32i instructions with base pointing at task_struct, breaking build with the following messages: arch/xtensa/kernel/entry.S: Assembler messages: arch/xtensa/kernel/entry.S:1002: Error: operand 3 of 'l32i.n' has invalid value '1048' arch/xtensa/kernel/entry.S:1831: Error: operand 3 of 's32i.n' has invalid value '1040' arch/xtensa/kernel/entry.S:1832: Error: operand 3 of 's32i.n' has invalid value '1044' Change base to point to task_struct::thread in such cases. Don't use a10 in _switch_to to save/restore prev pointer as a2 is not clobbered. Cc: stable@vger.kernel.org Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-08-14xtensa: fix address checks in dma_{alloc,free}_coherentAlan Douglas
Virtual address is translated to the XCHAL_KSEG_CACHED region in the dma_free_coherent, but is checked to be in the 0...XCHAL_KSEG_SIZE range. Change check for end of the range from 'addr >= X' to 'addr > X - 1' to handle the case of X == 0. Replace 'if (C) BUG();' construct with 'BUG_ON(C);'. Cc: stable@vger.kernel.org Signed-off-by: Alan Douglas <adouglas@cadence.com> Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-08-06xtensa: Use get_signal() signal_setup_done()Richard Weinberger
Use the more generic functions get_signal() signal_setup_done() for signal delivery. Signed-off-by: Richard Weinberger <richard@nod.at>
2014-07-15Merge tag 'xtensa-for-next-20140715' of ↵Chris Zankel
git://github.com/jcmvbkbc/linux-xtensa into for_next Xtensa fixes for 3.16: - resolve FIXMEs in double exception handler for window overflow. This fix makes native building of linux on xtensa host possible; - fix sysmem region removal issue introduced in 3.15.
2014-06-09xtensa: add fixup for double exception raised in window overflowMax Filippov
There are two FIXMEs in the double exception handler 'for the extremely unlikely case'. This case gets hit by gcc during kernel build once in a few hours, resulting in an unrecoverable exception condition. Provide missing fixup routine to handle this case. Double exception literals now need 8 more bytes, add them to the linker script. Also replace bbsi instructions with bbsi.l as we're branching depending on 8th and 7th LSB-based bits of exception address. This may be tested by adding the explicit DTLB invalidation to window overflow handlers, like the following: --- a/arch/xtensa/kernel/vectors.S +++ b/arch/xtensa/kernel/vectors.S @@ -592,6 +592,14 @@ ENDPROC(_WindowUnderflow4) ENTRY_ALIGN64(_WindowOverflow8) s32e a0, a9, -16 + bbsi.l a9, 31, 1f + rsr a0, ccount + bbsi.l a0, 4, 1f + pdtlb a0, a9 + idtlb a0 + movi a0, 9 + idtlb a0 +1: l32e a0, a1, -12 s32e a2, a9, -8 s32e a1, a9, -12 Cc: stable@vger.kernel.org Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-05-13Merge branch 'dt-bus-name' into for-nextRob Herring
2014-05-05Merge tag 'xtensa-next-20140503' of git://github.com/czankel/xtensa-linuxLinus Torvalds
Pull Xtensa fixes from Chris Zankel: - Fixes allmodconfig, allnoconfig builds - Adds highmem support - Enables build-time exception table sorting. * tag 'xtensa-next-20140503' of git://github.com/czankel/xtensa-linux: xtensa: ISS: don't depend on CONFIG_TTY xtensa: xt2000: drop redundant sysmem initialization xtensa: add support for KC705 xtensa: xtfpga: introduce SoC I/O bus xtensa: add HIGHMEM support xtensa: optimize local_flush_tlb_kernel_range xtensa: dump sysmem from the bootmem_init xtensa: handle memmap kernel option xtensa: keep sysmem banks ordered in mem_reserve xtensa: keep sysmem banks ordered in add_sysmem_bank xtensa: split bootparam and kernel meminfo xtensa: enable sorting extable at build time xtensa: export __{invalidate,flush}_dcache_range xtensa: Export __invalidate_icache_range
2014-04-30of/fdt: update of_get_flat_dt_prop in prep for libfdtRob Herring
Make of_get_flat_dt_prop arguments compatible with libfdt fdt_getprop call in preparation to convert FDT code to use libfdt. Make the return value const and the property length ptr type an int. Signed-off-by: Rob Herring <robh@kernel.org> Tested-by: Michal Simek <michal.simek@xilinx.com> Tested-by: Grant Likely <grant.likely@linaro.org> Tested-by: Stephen Chivers <schivers@csc.com>
2014-04-30of/fdt: consolidate built-in dtb section variablesRob Herring
Unify the various architectures __dtb_start and __dtb_end definitions moving them into of_fdt.h. Signed-off-by: Rob Herring <robh@kernel.org> Acked-by: Vineet Gupta <vgupta@synopsys.com> Acked-by: James Hogan <james.hogan@imgtec.com> Tested-by: Michal Simek <michal.simek@xilinx.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Jonas Bonn <jonas@southpole.se> Cc: Chris Zankel <chris@zankel.net> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: linux-metag@vger.kernel.org Cc: linux-mips@linux-mips.org Cc: linux@lists.openrisc.net Cc: linux-xtensa@linux-xtensa.org Tested-by: Grant Likely <grant.likely@linaro.org> Tested-by: Stephen Chivers <schivers@csc.com>
2014-04-06xtensa: optimize local_flush_tlb_kernel_rangeMax Filippov
Don't flush whole TLB if only a small kernel range is requested. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-04-02xtensa: handle memmap kernel optionMax Filippov
This option is useful for reserving memory regions for secondary cores in AMP configurations. Implement the following memmap variants: - memmap=nn[KMG]@ss[KMG]: force usage of a specific region of memory; - memmap=nn[KMG]$ss[KMG]: mark specified memory as reserved; - memmap=nn[KMG]: set end of memory. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-04-02xtensa: keep sysmem banks ordered in mem_reserveMax Filippov
Rewrite mem_reserve so that it keeps bank order. Also make its return code more traditional. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-04-02xtensa: split bootparam and kernel meminfoMax Filippov
Bootparam meminfo is a bootloader ABI, kernel meminfo is for the kernel bookkeeping, keep them separate. Kernel doesn't care of memory region types, so drop the type field and don't pass it to add_sysmem_bank. Move kernel sysmem structures and prototypes to asm/sysmem.h and sysmem variable and add_sysmem_bank to mm/init.c Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-04-02xtensa: export __{invalidate,flush}_dcache_rangeMax Filippov
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-04-02xtensa: Export __invalidate_icache_rangeGeert Uytterhoeven
When modular code calls flush_icache_range(): ERROR: "__invalidate_icache_range" [drivers/misc/lkdtm.ko] undefined! make[1]: *** [__modpost] Error 1 Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-03-12Merge branch 'irq/for-gpio' into irq/coreThomas Gleixner
Merge the request/release callbacks which are in a separate branch for consumption by the gpio folks. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-03-04xtensa: Use irq_set_affinity instead of homebrewn codeThomas Gleixner
There is no point in having an incomplete copy of irq_set_affinity() for the hotplug irq migration code. Use the core function instead and while at it switch to for_each_active_irq() Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Chris Zankel <chris@zankel.net> Cc: xtensa <linux-xtensa@linux-xtensa.org> Link: http://lkml.kernel.org/r/20140223212736.664624945@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-24Merge tag 'xtensa-for-next-20140221-1' into for_nextChris Zankel
Xtensa fixes for 3.14: - allow booting xtfpga on boards with new uBoot and >128MBytes memory; - drop nonexistent GPIO32 support from fsf variant; - don't select USE_GENERIC_SMP_HELPERS; - enable common clock framework support, set up ethoc clock on xtfpga; - wire up sched_setattr and sched_getattr syscalls. Signed-off-by: Chris Zankel <chris@zankel.net>
2014-02-21xtensa: support common clock frameworkMax Filippov
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-01-29xtensa: fix fast_syscall_spill_registersChris Zankel
The original implementation could clobber registers under certain conditions. The Xtensa processor architecture uses windowed registers and the original implementation was using a4 as a temporary register, which under certain conditions could be register a0 of the oldest window frame, and didn't always restore the content correctly. By moving the _spill_registers routine inside the fast system call, it frees up one more register (the return address is not required anymore) for the spill routine. Signed-off-by: Chris Zankel <chris@zankel.net>
2014-01-28xtensa: fix fast_syscall_spill_registersChris Zankel
The original implementation could clobber registers under certain conditions. The Xtensa processor architecture uses windowed registers and the original implementation was using a4 as a temporary register, which under certain conditions could be register a0 of the oldest window frame, and didn't always restore the content correctly. By moving the _spill_registers routine inside the fast system call, it frees up one more register (the return address is not required anymore) for the spill routine. Signed-off-by: Chris Zankel <chris@zankel.net>
2014-01-25xtensa: save current register frame in fast_syscall_spill_registers_fixupMax Filippov
We need it saved because it contains a3 where we track which register windows we still need to spill, and fixup handler may call C exception handlers. Also fix comments. Cc: stable@vger.kernel.org Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-01-25xtensa: introduce spill_registers_kernel macroMax Filippov
Most in-kernel users want registers spilled on the kernel stack and don't require PS.EXCM to be set. That means that they don't need fixup routine and could reuse regular window overflow mechanism for that, which makes spill routine very simple. Cc: stable@vger.kernel.org Suggested-by: Chris Zankel <chris@zankel.net> Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-01-19xtensa: export ccount_freqMax Filippov
Now that ccount_freq is used in udelay and ndelay it needs to be exported in order to be available to modules. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-01-15xtensa: remap io area defined in device treeBaruch Siach
Use the simple-bus node to discover the io area, and remap the cached and bypass io ranges. The parent-bus-address value of the first triplet in the "ranges" property is used. This value is rounded down to the nearest 256MB boundary. The length of the io area is fixed at 256MB; the "ranges" property length value is ignored. Other limitations: (1) only the first simple-bus node is considered, and (2) only the first triplet of the "ranges" property is considered. See ePAPR 1.1 §6.5 for the simple-bus node description, and §2.3.8 for the "ranges" property description. Signed-off-by: Baruch Siach <baruch@tkos.co.il> Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-01-15xtensa: support default device tree busesBaruch Siach
This currently includes simple-bus. Signed-off-by: Baruch Siach <baruch@tkos.co.il> Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-01-15xtensa: initialize device tree clock sourcesBaruch Siach
Signed-off-by: Baruch Siach <baruch@tkos.co.il> Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-01-15xtensa: Enable irqs after cpu is set onlineKirill Tkhai
there is a small possibility that wake_up of softirq thread happens between local_irq_enable() and set_cpu_online(). In this case affinity of the thread changes to fallback affinity (i.e. CPU0). This may be a source of problems. The patch kills that possibility. Signed-off-by: Kirill Tkhai <tkhai@yandex.ru> Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-01-14xtensa: Switch to sched_clock_register()Stephen Boyd
The 32 bit sched_clock interface now supports 64 bits. Upgrade to the 64 bit function to allow us to remove the 32 bit registration interface. Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Acked-by: Max Filippov <jcmvbkbc@gmail.com> Signed-off-by: Chris Zankel <chris@zankel.net>
2014-01-14xtensa: implement CPU hotplugMax Filippov
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com> Signed-off-by: Chris Zankel <chris@zankel.net>
2014-01-14xtensa: add SMP supportMax Filippov
This is largely based on SMP code from the xtensa-2.6.29-smp tree by Piet Delaney, Marc Gauthier, Joe Taylor, Christian Zankel (and possibly other Tensilica folks). Signed-off-by: Max Filippov <jcmvbkbc@gmail.com> Signed-off-by: Chris Zankel <chris@zankel.net>
2014-01-14xtensa: add MX irqchipMax Filippov
MX is an interrupt distributor used in some SMP-capable xtensa configurations. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com> Signed-off-by: Chris Zankel <chris@zankel.net>
2014-01-14xtensa: clear timer IRQ unconditionally in its handlerMax Filippov
PIC irq_ack doesn't clear timer IRQ, because timer interrupt handler usually set up new timer by writing to ccompare register and thus clearing timer IRQ. However timer may not be set up in the IRQ handler, e.g. with tickless idle on SMP, or when CPU is going offline, leaving timer IRQ raised and making do_interrupt attempting to handle it forever. To fix this always write current value of ccompare SR chosen to be linux timer back to that SR on entry to timer interrupt handler. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com> Signed-off-by: Chris Zankel <chris@zankel.net>
2014-01-14xtensa: clean up do_interrupt/do_IRQMax Filippov
- set up irq registers and call irq_enter/irq_exit once for each kernel entry due to interrupt; - don't attempt to clear current IRQ in the do_interrupt, IRQ handler will take care of it; - find pending interrupt with highest priority before every ISR invocation. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com> Signed-off-by: Chris Zankel <chris@zankel.net>
2014-01-14xtensa: move built-in PIC to drivers/irqchipMax Filippov
Extract xtensa built-in interrupt controller implementation from xtensa/kernel/irq.c and move it to other irqchips, providing way to instantiate it from the device tree. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com> Signed-off-by: Chris Zankel <chris@zankel.net>
2014-01-14xtensa: move init_mmu declaration to mmu_context.hMax Filippov
Secondary CPUs need this declaration to initialize their MMUs. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com> Signed-off-by: Chris Zankel <chris@zankel.net>
2014-01-14xtensa: call check_s32c1i after trap_initMax Filippov
Otherwise exceptions may occur prior to exception handling mechanism initialization, resulting in silently dead system. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com> Signed-off-by: Chris Zankel <chris@zankel.net>
2014-01-14xtensa: update clockevent setup for SMPMax Filippov
Provide per-cpu ccount_timer objects and use them appropriately. Extract per-cpu clockevent setup function. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com> Signed-off-by: Chris Zankel <chris@zankel.net>