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9762f12d3e
linux/arch/arm
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Dave Martin 9762f12d3e ARM: mcpm: Add baremetal voting mutexes 
This patch adds a simple low-level voting mutex implementation
to be used to arbitrate during first man selection when no load/store
exclusive instructions are usable.

For want of a better name, these are called "vlocks".  (I was
tempted to call them ballot locks, but "block" is way too confusing
an abbreviation...)

There is no function to wait for the lock to be released, and no
vlock_lock() function since we don't need these at the moment.
These could straightforwardly be added if vlocks get used for other
purposes.

For architectural correctness even Strongly-Ordered memory accesses
require barriers in order to guarantee that multiple CPUs have a
coherent view of the ordering of memory accesses.  Whether or not
this matters depends on hardware implementation details of the
memory system.  Since the purpose of this code is to provide a clean,
generic locking mechanism with no platform-specific dependencies the
barriers should be present to avoid unpleasant surprises on future
platforms.

Note:

  * When taking the lock, we don't care about implicit background
    memory operations and other signalling which may be pending,
    because those are not part of the critical section anyway.

    A DMB is sufficient to ensure correctly observed ordering if
    the explicit memory accesses in vlock_trylock.

  * No barrier is required after checking the election result,
    because the result is determined by the store to
    VLOCK_OWNER_OFFSET and is already globally observed due to the
    barriers in voting_end.  This means that global agreement on
    the winner is guaranteed, even before the winner is known
    locally.

Signed-off-by: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
2013-04-24 10:37:01 -04:00
..
boot This is the first batch of MFD fixes for 3.9. 2013-03-15 17:34:01 -07:00
common ARM: mcpm: Add baremetal voting mutexes 2013-04-24 10:37:01 -04:00
configs Fix few regressions, omap3 pm init with device tree, and some 2013-03-05 23:22:00 +01:00
crypto
include ARM: mcpm: introduce helpers for platform coherency exit/setup 2013-04-24 10:37:00 -04:00
kernel ARM: mcpm: introduce helpers for platform coherency exit/setup 2013-04-24 10:37:00 -04:00
kvm ARM: KVM: fix compilation after removal of user_alloc from struct kvm_memory_slot 2013-02-25 11:48:41 +02:00
lib ARM: 7670/1: fix the memset fix 2013-03-12 12:18:47 +00:00
mach-at91 ARM: w1-gpio: fix erroneous gpio requests 2013-03-12 16:20:45 -07:00
mach-bcm Merge remote-tracking branches 'arm-soc/irqchip/gic-vic-move' and 'arm-soc/timer/cleanup' into soc 2013-01-24 17:57:20 +09:00
mach-bcm2835 arm-soc: soc-specific updates 2013-02-21 15:27:22 -08:00
mach-clps711x The series cleans up ARCH_HAS_DECOMP_WDOG and arch_decomp_wdog which 2013-02-05 10:26:20 -08:00
mach-cns3xxx The series cleans up ARCH_HAS_DECOMP_WDOG and arch_decomp_wdog which 2013-02-05 10:26:20 -08:00
mach-davinci Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
mach-dove arm-soc: mvebu platform changes 2013-02-28 20:09:24 -08:00
mach-ebsa110 The series cleans up ARCH_HAS_DECOMP_WDOG and arch_decomp_wdog which 2013-02-05 10:26:20 -08:00
mach-ep93xx The series cleans up ARCH_HAS_DECOMP_WDOG and arch_decomp_wdog which 2013-02-05 10:26:20 -08:00
mach-exynos Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
mach-footbridge The series cleans up ARCH_HAS_DECOMP_WDOG and arch_decomp_wdog which 2013-02-05 10:26:20 -08:00
mach-gemini The series cleans up ARCH_HAS_DECOMP_WDOG and arch_decomp_wdog which 2013-02-05 10:26:20 -08:00
mach-h720x The series cleans up ARCH_HAS_DECOMP_WDOG and arch_decomp_wdog which 2013-02-05 10:26:20 -08:00
mach-highbank Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
mach-imx ARM: imx: pll1_sys should be an initial on clk 2013-03-11 10:44:40 +08:00
mach-integrator Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
mach-iop13xx Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
mach-iop32x The series cleans up ARCH_HAS_DECOMP_WDOG and arch_decomp_wdog which 2013-02-05 10:26:20 -08:00
mach-iop33x The series cleans up ARCH_HAS_DECOMP_WDOG and arch_decomp_wdog which 2013-02-05 10:26:20 -08:00
mach-ixp4xx ARM: w1-gpio: fix erroneous gpio requests 2013-03-12 16:20:45 -07:00
mach-kirkwood ARM: kirkwood: fix to retain gbe MAC addresses for DT kernels 2013-03-08 21:34:16 +00:00
mach-ks8695 Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
mach-l7200/include/mach
mach-lpc32xx The series cleans up ARCH_HAS_DECOMP_WDOG and arch_decomp_wdog which 2013-02-05 10:26:20 -08:00
mach-mmp Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
mach-msm Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
mach-mv78xx0 Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
mach-mvebu arm-soc: mvebu platform changes 2013-02-28 20:09:24 -08:00
mach-mxs ARM: mxs: cfa10049: Fix fb initialisation function 2013-03-07 10:54:23 +08:00
mach-netx ARM: 7642/1: netx: bump IRQ offset to 64 2013-03-03 22:54:11 +00:00
mach-nomadik Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
mach-omap1 ARM: OMAP1: Fix build related to kgdb.h no longer including serial_8250.h 2013-03-04 11:12:16 -08:00
mach-omap2 ARM: OMAP: RX-51: add missing USB phy binding 2013-03-05 08:24:56 -08:00
mach-orion5x Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
mach-picoxcell Merge remote-tracking branches 'arm-soc/irqchip/gic-vic-move' and 'arm-soc/timer/cleanup' into soc 2013-01-24 17:57:20 +09:00
mach-prima2 Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
mach-pxa ARM: w1-gpio: fix erroneous gpio requests 2013-03-12 16:20:45 -07:00
mach-realview arm-soc: cleanups 2013-02-21 14:58:40 -08:00
mach-rpc The series cleans up ARCH_HAS_DECOMP_WDOG and arch_decomp_wdog which 2013-02-05 10:26:20 -08:00
mach-s3c24xx Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
mach-s3c64xx Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
mach-s5p64x0 arm-soc: cleanups 2013-02-21 14:58:40 -08:00
mach-s5pc100 Merge remote-tracking branches 'arm-soc/irqchip/gic-vic-move' and 'arm-soc/timer/cleanup' into soc 2013-01-24 17:57:20 +09:00
mach-s5pv210 Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media 2013-02-24 17:35:10 -08:00
mach-sa1100 Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
mach-shark The series cleans up ARCH_HAS_DECOMP_WDOG and arch_decomp_wdog which 2013-02-05 10:26:20 -08:00
mach-shmobile IOMMU Updates for Linux v3.9 2013-02-26 11:09:17 -08:00
mach-socfpga Merge branch 'socfpga/hw' into next/soc 2013-02-11 19:37:51 -08:00
mach-spear3xx ARM: spear3xx: Use correct pl080 header file 2013-03-12 10:56:32 +01:00
mach-spear6xx Merge branch 'next' of git://git.infradead.org/users/vkoul/slave-dma 2013-02-26 09:24:48 -08:00
mach-spear13xx Revert "ARM: SPEAr13xx: Pass DW DMAC platform data from DT" 2013-02-20 15:48:02 +05:30
mach-sunxi Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
mach-tegra Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
mach-u300 Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
mach-ux500 Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
mach-versatile Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
mach-vexpress Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
mach-virt ARM: mach-virt: fixup machine descriptor after removal of sys_timer 2013-02-11 10:39:30 -08:00
mach-vt8500 arm-soc: soc-specific updates 2013-02-21 15:27:22 -08:00
mach-w90x900 arm-soc: cleanups 2013-02-21 14:58:40 -08:00
mach-zynq arm: zynq: Add missing irqchip.h to common.c 2013-01-29 10:55:28 -08:00
mm Merge branch 'fixes-for-3.9' of git://git.linaro.org/people/mszyprowski/linux-dma-mapping 2013-03-15 17:35:03 -07:00
net ARM: net: bpf_jit: fix emit_swap16() for non ARMv6+. 2013-02-14 13:26:44 -05:00
nwfpe
oprofile
plat-iop
plat-omap arm-soc: late OMAP changes 2013-02-28 20:00:40 -08:00
plat-orion arm: plat-orion: fix address decoding when > 4GB is used 2013-03-08 22:07:19 +00:00
plat-pxa
plat-samsung Merge branch 'timer/cleanup' into late/mvebu2 2013-02-28 18:54:15 +01:00
plat-spear ARM: SPEAr13xx: Fix typo "ARCH_HAVE_CPUFREQ" 2013-03-05 23:30:24 +01:00
plat-versatile Merge branch 'for-arm-soc/arch-timers' of git://git.kernel.org/pub/scm/linux/kernel/git/will/linux into kvm-arm/timer 2013-02-11 19:03:52 +00:00
tools
vfp ARM: Fix broken commit 0cc41e4a21 corrupting kernel messages 2013-03-01 21:09:59 +00:00
xen xen: implement updated XENMEM_add_to_physmap_range ABI 2013-02-19 22:01:55 -05:00
Kconfig ARM: multi-cluster PM: secondary kernel entry code 2013-04-24 10:36:59 -04:00
Kconfig-nommu
Kconfig.debug ARM: imx: fix typo "DEBUG_IMX50_IMX53_UART" 2013-03-11 21:28:18 +08:00
Makefile arm-soc: virtualization changes 2013-02-21 15:40:16 -08:00