linux/drivers/clocksource/Kconfig

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# SPDX-License-Identifier: GPL-2.0-only
menu "Clock Source drivers"
clocksource: Improve GENERIC_CLOCKEVENTS dependency We regularly run into build errors when a clocksource driver selects CONFIG_TIMER_OF while CONFIG_GENERIC_CLOCKEVENTS is disabled: In file included from drivers/clocksource/timer-of.c:25:0: drivers/clocksource/timer-of.h:35:28: error: field 'clkevt' has incomplete type At the moment, three drivers can show this behavior: ARMV7M_SYSTICK, CLKSRC_ST_LPC and CLKSRC_NPS. We could add further dependencies as we did many times, but I have looked a little bit more at what architectures are left that don't use GENERIC_CLOCKEVENTS, and this shows that there is a better solution. On arch/frv and arch/ia64, we never select CONFIG_GENERIC_CLOCKEVENTS and we also don't use ARCH_USES_GETTIMEOFFSET, which would block the clocksource Kconfig menu. On m68k, some platforms use CONFIG_GENERIC_CLOCKEVENTS, some use ARCH_USES_GETTIMEOFFSET, and some use neither of them. The good news is that there is no configuration that does not set CONFIG_GENERIC_CLOCKEVENTS but that wants to enable any of the Kconfig symbols in the menu, so we can simply replace the dependency with the stricter one. While in theory one could have a clocksource driver without the clockevent infrastructure, this seems unlikely to be relevant in the future any more. We can probably drop some of the other dependencies as well now, e.g. there should generally be no reason to depend on CONFIG_ARM unless the driver uses architecture specific assembly. Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
2017-09-05 15:04:56 +00:00
depends on GENERIC_CLOCKEVENTS
config TIMER_OF
bool
select TIMER_PROBE
config TIMER_ACPI
bool
select TIMER_PROBE
config TIMER_PROBE
bool
config CLKSRC_I8253
bool
config CLKEVT_I8253
bool
config I8253_LOCK
bool
config OMAP_DM_TIMER
bool
config CLKBLD_I8253
def_bool y if CLKSRC_I8253 || CLKEVT_I8253 || I8253_LOCK
config CLKSRC_MMIO
bool
config BCM2835_TIMER
bool "BCM2835 timer driver" if COMPILE_TEST
select CLKSRC_MMIO
help
Enables the support for the BCM2835 timer driver.
config BCM_KONA_TIMER
bool "BCM mobile timer driver" if COMPILE_TEST
select CLKSRC_MMIO
help
Enables the support for the BCM Kona mobile timer driver.
config DAVINCI_TIMER
bool "Texas Instruments DaVinci timer driver" if COMPILE_TEST
help
Enables the support for the TI DaVinci timer driver.
config DIGICOLOR_TIMER
bool "Digicolor timer driver" if COMPILE_TEST
select CLKSRC_MMIO
depends on HAS_IOMEM
help
Enables the support for the digicolor timer driver.
config DW_APB_TIMER
bool "DW APB timer driver" if COMPILE_TEST
help
Enables the support for the dw_apb timer.
config DW_APB_TIMER_OF
bool
select DW_APB_TIMER
select TIMER_OF
config FTTMR010_TIMER
bool "Faraday Technology timer driver" if COMPILE_TEST
depends on HAS_IOMEM
select CLKSRC_MMIO
select TIMER_OF
select MFD_SYSCON
help
Enables support for the Faraday Technology timer block
FTTMR010.
config IXP4XX_TIMER
bool "Intel XScale IXP4xx timer driver" if COMPILE_TEST
depends on HAS_IOMEM
select CLKSRC_MMIO
help
Enables support for the Intel XScale IXP4xx SoC timer.
config ROCKCHIP_TIMER
bool "Rockchip timer driver" if COMPILE_TEST
depends on ARM || ARM64
select TIMER_OF
select CLKSRC_MMIO
help
Enables the support for the Rockchip timer driver.
config ARMADA_370_XP_TIMER
bool "Armada 370 and XP timer driver" if COMPILE_TEST
depends on ARM
select TIMER_OF
select CLKSRC_MMIO
help
Enables the support for the Armada 370 and XP timer driver.
config MESON6_TIMER
bool "Meson6 timer driver" if COMPILE_TEST
select CLKSRC_MMIO
help
Enables the support for the Meson6 timer driver.
config ORION_TIMER
bool "Orion timer driver" if COMPILE_TEST
depends on ARM
select TIMER_OF
select CLKSRC_MMIO
help
Enables the support for the Orion timer driver
config OWL_TIMER
bool "Owl timer driver" if COMPILE_TEST
select CLKSRC_MMIO
help
Enables the support for the Actions Semi Owl timer driver.
config RDA_TIMER
bool "RDA timer driver" if COMPILE_TEST
depends on GENERIC_CLOCKEVENTS
select CLKSRC_MMIO
select TIMER_OF
help
Enables the support for the RDA Micro timer driver.
config SUN4I_TIMER
bool "Sun4i timer driver" if COMPILE_TEST
depends on HAS_IOMEM
select CLKSRC_MMIO
select TIMER_OF
help
Enables support for the Sun4i timer.
config SUN5I_HSTIMER
bool "Sun5i timer driver" if COMPILE_TEST
select CLKSRC_MMIO
depends on COMMON_CLK
help
Enables support the Sun5i timer.
config TEGRA_TIMER
bool "Tegra timer driver" if COMPILE_TEST
select CLKSRC_MMIO
select TIMER_OF
depends on ARCH_TEGRA || COMPILE_TEST
help
Enables support for the Tegra driver.
config VT8500_TIMER
bool "VT8500 timer driver" if COMPILE_TEST
depends on HAS_IOMEM
help
Enables support for the VT8500 driver.
config NPCM7XX_TIMER
bool "NPCM7xx timer driver" if COMPILE_TEST
depends on HAS_IOMEM
select TIMER_OF
select CLKSRC_MMIO
help
Enable 24-bit TIMER0 and TIMER1 counters in the NPCM7xx architecture,
where TIMER0 serves as clockevent and TIMER1 serves as clocksource.
config CADENCE_TTC_TIMER
bool "Cadence TTC timer driver" if COMPILE_TEST
depends on COMMON_CLK
help
Enables support for the Cadence TTC driver.
config ASM9260_TIMER
bool "ASM9260 timer driver" if COMPILE_TEST
select CLKSRC_MMIO
select TIMER_OF
help
Enables support for the ASM9260 timer.
config CLKSRC_NOMADIK_MTU
bool "Nomakdik clocksource driver" if COMPILE_TEST
depends on ARM
select CLKSRC_MMIO
help
Support for Multi Timer Unit. MTU provides access
to multiple interrupt generating programmable
32-bit free running decrementing counters.
config CLKSRC_DBX500_PRCMU
bool "Clocksource PRCMU Timer" if COMPILE_TEST
depends on HAS_IOMEM
help
Use the always on PRCMU Timer as clocksource.
config CLPS711X_TIMER
bool "Cirrus Logic timer driver" if COMPILE_TEST
select CLKSRC_MMIO
help
Enables support for the Cirrus Logic PS711 timer.
config ATLAS7_TIMER
bool "Atlas7 timer driver" if COMPILE_TEST
select CLKSRC_MMIO
help
Enables support for the Atlas7 timer.
config MXS_TIMER
bool "MXS timer driver" if COMPILE_TEST
select CLKSRC_MMIO
select STMP_DEVICE
help
Enables support for the MXS timer.
config PRIMA2_TIMER
bool "Prima2 timer driver" if COMPILE_TEST
select CLKSRC_MMIO
help
Enables support for the Prima2 timer.
config U300_TIMER
bool "U300 timer driver" if COMPILE_TEST
depends on ARM
select CLKSRC_MMIO
help
Enables support for the U300 timer.
config NSPIRE_TIMER
bool "NSpire timer driver" if COMPILE_TEST
select CLKSRC_MMIO
help
Enables support for the Nspire timer.
config KEYSTONE_TIMER
bool "Keystone timer driver" if COMPILE_TEST
depends on ARM || ARM64
select CLKSRC_MMIO
help
Enables support for the Keystone timer.
config INTEGRATOR_AP_TIMER
bool "Integrator-AP timer driver" if COMPILE_TEST
select CLKSRC_MMIO
help
Enables support for the Integrator-AP timer.
config CLKSRC_EFM32
bool "Clocksource for Energy Micro's EFM32 SoCs" if !ARCH_EFM32
depends on OF && ARM && (ARCH_EFM32 || COMPILE_TEST)
select CLKSRC_MMIO
default ARCH_EFM32
help
Support to use the timers of EFM32 SoCs as clock source and clock
event device.
config CLKSRC_LPC32XX
bool "Clocksource for LPC32XX" if COMPILE_TEST
clocksource: Improve GENERIC_CLOCKEVENTS dependency We regularly run into build errors when a clocksource driver selects CONFIG_TIMER_OF while CONFIG_GENERIC_CLOCKEVENTS is disabled: In file included from drivers/clocksource/timer-of.c:25:0: drivers/clocksource/timer-of.h:35:28: error: field 'clkevt' has incomplete type At the moment, three drivers can show this behavior: ARMV7M_SYSTICK, CLKSRC_ST_LPC and CLKSRC_NPS. We could add further dependencies as we did many times, but I have looked a little bit more at what architectures are left that don't use GENERIC_CLOCKEVENTS, and this shows that there is a better solution. On arch/frv and arch/ia64, we never select CONFIG_GENERIC_CLOCKEVENTS and we also don't use ARCH_USES_GETTIMEOFFSET, which would block the clocksource Kconfig menu. On m68k, some platforms use CONFIG_GENERIC_CLOCKEVENTS, some use ARCH_USES_GETTIMEOFFSET, and some use neither of them. The good news is that there is no configuration that does not set CONFIG_GENERIC_CLOCKEVENTS but that wants to enable any of the Kconfig symbols in the menu, so we can simply replace the dependency with the stricter one. While in theory one could have a clocksource driver without the clockevent infrastructure, this seems unlikely to be relevant in the future any more. We can probably drop some of the other dependencies as well now, e.g. there should generally be no reason to depend on CONFIG_ARM unless the driver uses architecture specific assembly. Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
2017-09-05 15:04:56 +00:00
depends on HAS_IOMEM
depends on ARM
select CLKSRC_MMIO
select TIMER_OF
help
Support for the LPC32XX clocksource.
config CLKSRC_PISTACHIO
bool "Clocksource for Pistachio SoC" if COMPILE_TEST
clocksource: Improve GENERIC_CLOCKEVENTS dependency We regularly run into build errors when a clocksource driver selects CONFIG_TIMER_OF while CONFIG_GENERIC_CLOCKEVENTS is disabled: In file included from drivers/clocksource/timer-of.c:25:0: drivers/clocksource/timer-of.h:35:28: error: field 'clkevt' has incomplete type At the moment, three drivers can show this behavior: ARMV7M_SYSTICK, CLKSRC_ST_LPC and CLKSRC_NPS. We could add further dependencies as we did many times, but I have looked a little bit more at what architectures are left that don't use GENERIC_CLOCKEVENTS, and this shows that there is a better solution. On arch/frv and arch/ia64, we never select CONFIG_GENERIC_CLOCKEVENTS and we also don't use ARCH_USES_GETTIMEOFFSET, which would block the clocksource Kconfig menu. On m68k, some platforms use CONFIG_GENERIC_CLOCKEVENTS, some use ARCH_USES_GETTIMEOFFSET, and some use neither of them. The good news is that there is no configuration that does not set CONFIG_GENERIC_CLOCKEVENTS but that wants to enable any of the Kconfig symbols in the menu, so we can simply replace the dependency with the stricter one. While in theory one could have a clocksource driver without the clockevent infrastructure, this seems unlikely to be relevant in the future any more. We can probably drop some of the other dependencies as well now, e.g. there should generally be no reason to depend on CONFIG_ARM unless the driver uses architecture specific assembly. Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
2017-09-05 15:04:56 +00:00
depends on HAS_IOMEM
select TIMER_OF
help
Enables the clocksource for the Pistachio SoC.
config CLKSRC_TI_32K
bool "Texas Instruments 32.768 Hz Clocksource" if COMPILE_TEST
depends on GENERIC_SCHED_CLOCK
select TIMER_OF if OF
help
This option enables support for Texas Instruments 32.768 Hz clocksource
available on many OMAP-like platforms.
config CLKSRC_NPS
bool "NPS400 clocksource driver" if COMPILE_TEST
depends on !PHYS_ADDR_T_64BIT
select CLKSRC_MMIO
select TIMER_OF if OF
help
NPS400 clocksource support.
It has a 64-bit counter with update rate up to 1000MHz.
This counter is accessed via couple of 32-bit memory-mapped registers.
config CLKSRC_STM32
clocksource: Increase dependencies of timer-stm32 to limit build wreckage This driver leaks out into arch/parisc builds that don't have CONFIG_GENERIC_CLOCKEVENTS, leading to the following (truncated) wreckage: CC drivers/clocksource/timer-stm32.o drivers/clocksource/timer-stm32.c:38:28: error: field 'evtdev' has incomplete type drivers/clocksource/timer-stm32.c:44:19: warning: 'enum clock_event_mode' declared inside parameter list drivers/clocksource/timer-stm32.c:44:19: warning: its scope is only this definition or declaration, which is probably not what you want drivers/clocksource/timer-stm32.c:43:62: error: parameter 1 ('mode') has incomplete type drivers/clocksource/timer-stm32.c:43:13: error: function declaration isn't a prototype drivers/clocksource/timer-stm32.c: In function 'stm32_clock_event_set_mode': drivers/clocksource/timer-stm32.c:47:3: error: type defaults to 'int' in declaration of '__mptr' drivers/clocksource/timer-stm32.c:47:3: warning: initialization from incompatible pointer type drivers/clocksource/timer-stm32.c:51:7: error: 'CLOCK_EVT_MODE_PERIODIC' undeclared (first use in this function) drivers/clocksource/timer-stm32.c:51:7: note: each undeclared identifier is reported only once for each function it appears in drivers/clocksource/timer-stm32.c:56:7: error: 'CLOCK_EVT_MODE_ONESHOT' undeclared (first use in this function) Tighten up the dependencies to limit where it gets built by copying the style of the Kconfig line for CLKSRC_EFM32 a few lines above. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Linus Walleij <linus.walleij@linaro.org> Cc: Chanwoo Choi <cw00.choi@samsung.com> Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Link: http://lkml.kernel.org/r/1434841352-24300-1-git-send-email-paul.gortmaker@windriver.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-06-20 23:02:32 +00:00
bool "Clocksource for STM32 SoCs" if !ARCH_STM32
depends on OF && ARM && (ARCH_STM32 || COMPILE_TEST)
select CLKSRC_MMIO
select TIMER_OF
config CLKSRC_MPS2
bool "Clocksource for MPS2 SoCs" if COMPILE_TEST
depends on GENERIC_SCHED_CLOCK
select CLKSRC_MMIO
select TIMER_OF
config ARC_TIMERS
bool "Support for 32-bit TIMERn counters in ARC Cores" if COMPILE_TEST
clocksource/drivers/arc_timer: Utilize generic sched_clock It turned out we used to use default implementation of sched_clock() from kernel/sched/clock.c which was as precise as 1/HZ, i.e. by default we had 10 msec granularity of time measurement. Now given ARC built-in timers are clocked with the same frequency as CPU cores we may get much higher precision of time tracking. Thus we switch to generic sched_clock which really reads ARC hardware counters. This is especially helpful for measuring short events. That's what we used to have: ------------------------------>8------------------------ $ perf stat /bin/sh -c /root/lmbench-master/bin/arc/hello > /dev/null Performance counter stats for '/bin/sh -c /root/lmbench-master/bin/arc/hello': 10.000000 task-clock (msec) # 2.832 CPUs utilized 1 context-switches # 0.100 K/sec 1 cpu-migrations # 0.100 K/sec 63 page-faults # 0.006 M/sec 3049480 cycles # 0.305 GHz 1091259 instructions # 0.36 insn per cycle 256828 branches # 25.683 M/sec 27026 branch-misses # 10.52% of all branches 0.003530687 seconds time elapsed 0.000000000 seconds user 0.010000000 seconds sys ------------------------------>8------------------------ And now we'll see: ------------------------------>8------------------------ $ perf stat /bin/sh -c /root/lmbench-master/bin/arc/hello > /dev/null Performance counter stats for '/bin/sh -c /root/lmbench-master/bin/arc/hello': 3.004322 task-clock (msec) # 0.865 CPUs utilized 1 context-switches # 0.333 K/sec 1 cpu-migrations # 0.333 K/sec 63 page-faults # 0.021 M/sec 2986734 cycles # 0.994 GHz 1087466 instructions # 0.36 insn per cycle 255209 branches # 84.947 M/sec 26002 branch-misses # 10.19% of all branches 0.003474829 seconds time elapsed 0.003519000 seconds user 0.000000000 seconds sys ------------------------------>8------------------------ Note how much more meaningful is the second output - time spent for execution pretty much matches number of cycles spent (we're runnign @ 1GHz here). Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Acked-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
2018-11-19 11:29:17 +00:00
depends on GENERIC_SCHED_CLOCK
select TIMER_OF
help
These are legacy 32-bit TIMER0 and TIMER1 counters found on all ARC cores
(ARC700 as well as ARC HS38).
TIMER0 serves as clockevent while TIMER1 provides clocksource.
config ARC_TIMERS_64BIT
bool "Support for 64-bit counters in ARC HS38 cores" if COMPILE_TEST
depends on ARC_TIMERS
select TIMER_OF
help
This enables 2 different 64-bit timers: RTC (for UP) and GFRC (for SMP).
RTC is implemented inside the core, while GFRC sits outside the core in
ARConnect IP block. Driver automatically picks one of them for clocksource
as appropriate.
config ARM_ARCH_TIMER
bool
select TIMER_OF if OF
select TIMER_ACPI if ACPI
config ARM_ARCH_TIMER_EVTSTREAM
bool "Enable ARM architected timer event stream generation by default"
default y if ARM_ARCH_TIMER
depends on ARM_ARCH_TIMER
help
This option enables support by default for event stream generation
based on the ARM architected timer. It is used for waking up CPUs
executing the wfe instruction at a frequency represented as a
power-of-2 divisor of the clock rate. The behaviour can also be
overridden on the command line using the
clocksource.arm_arch_timer.evtstream parameter.
The main use of the event stream is wfe-based timeouts of userspace
locking implementations. It might also be useful for imposing timeout
on wfe to safeguard against any programming errors in case an expected
event is not generated.
This must be disabled for hardware validation purposes to detect any
hardware anomalies of missing events.
config ARM_ARCH_TIMER_OOL_WORKAROUND
bool
config FSL_ERRATUM_A008585
bool "Workaround for Freescale/NXP Erratum A-008585"
default y
depends on ARM_ARCH_TIMER && ARM64
select ARM_ARCH_TIMER_OOL_WORKAROUND
help
This option enables a workaround for Freescale/NXP Erratum
A-008585 ("ARM generic timer may contain an erroneous
value"). The workaround will only be active if the
fsl,erratum-a008585 property is found in the timer node.
config HISILICON_ERRATUM_161010101
bool "Workaround for Hisilicon Erratum 161010101"
default y
select ARM_ARCH_TIMER_OOL_WORKAROUND
depends on ARM_ARCH_TIMER && ARM64
help
This option enables a workaround for Hisilicon Erratum
161010101. The workaround will be active if the hisilicon,erratum-161010101
property is found in the timer node.
config ARM64_ERRATUM_858921
bool "Workaround for Cortex-A73 erratum 858921"
default y
select ARM_ARCH_TIMER_OOL_WORKAROUND
depends on ARM_ARCH_TIMER && ARM64
help
This option enables a workaround applicable to Cortex-A73
(all versions), whose counter may return incorrect values.
The workaround will be dynamically enabled when an affected
core is detected.
clocksource/drivers/arch_timer: Workaround for Allwinner A64 timer instability The Allwinner A64 SoC is known[1] to have an unstable architectural timer, which manifests itself most obviously in the time jumping forward a multiple of 95 years[2][3]. This coincides with 2^56 cycles at a timer frequency of 24 MHz, implying that the time went slightly backward (and this was interpreted by the kernel as it jumping forward and wrapping around past the epoch). Investigation revealed instability in the low bits of CNTVCT at the point a high bit rolls over. This leads to power-of-two cycle forward and backward jumps. (Testing shows that forward jumps are about twice as likely as backward jumps.) Since the counter value returns to normal after an indeterminate read, each "jump" really consists of both a forward and backward jump from the software perspective. Unless the kernel is trapping CNTVCT reads, a userspace program is able to read the register in a loop faster than it changes. A test program running on all 4 CPU cores that reported jumps larger than 100 ms was run for 13.6 hours and reported the following: Count | Event -------+--------------------------- 9940 | jumped backward 699ms 268 | jumped backward 1398ms 1 | jumped backward 2097ms 16020 | jumped forward 175ms 6443 | jumped forward 699ms 2976 | jumped forward 1398ms 9 | jumped forward 356516ms 9 | jumped forward 357215ms 4 | jumped forward 714430ms 1 | jumped forward 3578440ms This works out to a jump larger than 100 ms about every 5.5 seconds on each CPU core. The largest jump (almost an hour!) was the following sequence of reads: 0x0000007fffffffff → 0x00000093feffffff → 0x0000008000000000 Note that the middle bits don't necessarily all read as all zeroes or all ones during the anomalous behavior; however the low 10 bits checked by the function in this patch have never been observed with any other value. Also note that smaller jumps are much more common, with backward jumps of 2048 (2^11) cycles observed over 400 times per second on each core. (Of course, this is partially explained by lower bits rolling over more frequently.) Any one of these could have caused the 95 year time skip. Similar anomalies were observed while reading CNTPCT (after patching the kernel to allow reads from userspace). However, the CNTPCT jumps are much less frequent, and only small jumps were observed. The same program as before (except now reading CNTPCT) observed after 72 hours: Count | Event -------+--------------------------- 17 | jumped backward 699ms 52 | jumped forward 175ms 2831 | jumped forward 699ms 5 | jumped forward 1398ms Further investigation showed that the instability in CNTPCT/CNTVCT also affected the respective timer's TVAL register. The following values were observed immediately after writing CNVT_TVAL to 0x10000000: CNTVCT | CNTV_TVAL | CNTV_CVAL | CNTV_TVAL Error --------------------+------------+--------------------+----------------- 0x000000d4a2d8bfff | 0x10003fff | 0x000000d4b2d8bfff | +0x00004000 0x000000d4a2d94000 | 0x0fffffff | 0x000000d4b2d97fff | -0x00004000 0x000000d4a2d97fff | 0x10003fff | 0x000000d4b2d97fff | +0x00004000 0x000000d4a2d9c000 | 0x0fffffff | 0x000000d4b2d9ffff | -0x00004000 The pattern of errors in CNTV_TVAL seemed to depend on exactly which value was written to it. For example, after writing 0x10101010: CNTVCT | CNTV_TVAL | CNTV_CVAL | CNTV_TVAL Error --------------------+------------+--------------------+----------------- 0x000001ac3effffff | 0x1110100f | 0x000001ac4f10100f | +0x1000000 0x000001ac40000000 | 0x1010100f | 0x000001ac5110100f | -0x1000000 0x000001ac58ffffff | 0x1110100f | 0x000001ac6910100f | +0x1000000 0x000001ac66000000 | 0x1010100f | 0x000001ac7710100f | -0x1000000 0x000001ac6affffff | 0x1110100f | 0x000001ac7b10100f | +0x1000000 0x000001ac6e000000 | 0x1010100f | 0x000001ac7f10100f | -0x1000000 I was also twice able to reproduce the issue covered by Allwinner's workaround[4], that writing to TVAL sometimes fails, and both CVAL and TVAL are left with entirely bogus values. One was the following values: CNTVCT | CNTV_TVAL | CNTV_CVAL --------------------+------------+-------------------------------------- 0x000000d4a2d6014c | 0x8fbd5721 | 0x000000d132935fff (615s in the past) Reviewed-by: Marc Zyngier <marc.zyngier@arm.com> ======================================================================== Because the CPU can read the CNTPCT/CNTVCT registers faster than they change, performing two reads of the register and comparing the high bits (like other workarounds) is not a workable solution. And because the timer can jump both forward and backward, no pair of reads can distinguish a good value from a bad one. The only way to guarantee a good value from consecutive reads would be to read _three_ times, and take the middle value only if the three values are 1) each unique and 2) increasing. This takes at minimum 3 counter cycles (125 ns), or more if an anomaly is detected. However, since there is a distinct pattern to the bad values, we can optimize the common case (1022/1024 of the time) to a single read by simply ignoring values that match the error pattern. This still takes no more than 3 cycles in the worst case, and requires much less code. As an additional safety check, we still limit the loop iteration to the number of max-frequency (1.2 GHz) CPU cycles in three 24 MHz counter periods. For the TVAL registers, the simple solution is to not use them. Instead, read or write the CVAL and calculate the TVAL value in software. Although the manufacturer is aware of at least part of the erratum[4], there is no official name for it. For now, use the kernel-internal name "UNKNOWN1". [1]: https://github.com/armbian/build/commit/a08cd6fe7ae9 [2]: https://forum.armbian.com/topic/3458-a64-datetime-clock-issue/ [3]: https://irclog.whitequark.org/linux-sunxi/2018-01-26 [4]: https://github.com/Allwinner-Homlet/H6-BSP4.9-linux/blob/master/drivers/clocksource/arm_arch_timer.c#L272 Acked-by: Maxime Ripard <maxime.ripard@bootlin.com> Tested-by: Andre Przywara <andre.przywara@arm.com> Signed-off-by: Samuel Holland <samuel@sholland.org> Cc: stable@vger.kernel.org Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
2019-01-13 02:17:18 +00:00
config SUN50I_ERRATUM_UNKNOWN1
bool "Workaround for Allwinner A64 erratum UNKNOWN1"
default y
depends on ARM_ARCH_TIMER && ARM64 && ARCH_SUNXI
select ARM_ARCH_TIMER_OOL_WORKAROUND
help
This option enables a workaround for instability in the timer on
the Allwinner A64 SoC. The workaround will only be active if the
allwinner,erratum-unknown1 property is found in the timer node.
config ARM_GLOBAL_TIMER
bool "Support for the ARM global timer" if COMPILE_TEST
select TIMER_OF if OF
depends on ARM
help
This option enables support for the ARM global timer unit.
config ARM_TIMER_SP804
bool "Support for Dual Timer SP804 module" if COMPILE_TEST
depends on GENERIC_SCHED_CLOCK && CLKDEV_LOOKUP
select CLKSRC_MMIO
select TIMER_OF if OF
config CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK
bool
depends on ARM_GLOBAL_TIMER
default y
help
Use ARM global timer clock source as sched_clock.
config ARMV7M_SYSTICK
bool "Support for the ARMv7M system time" if COMPILE_TEST
select TIMER_OF if OF
select CLKSRC_MMIO
help
This option enables support for the ARMv7M system timer unit.
config ATMEL_PIT
bool "Atmel PIT support" if COMPILE_TEST
depends on HAS_IOMEM
select TIMER_OF if OF
help
Support for the Periodic Interval Timer found on Atmel SoCs.
config ATMEL_ST
bool "Atmel ST timer support" if COMPILE_TEST
depends on HAS_IOMEM
select TIMER_OF
select MFD_SYSCON
help
Support for the Atmel ST timer.
config ATMEL_TCB_CLKSRC
bool "Atmel TC Block timer driver" if COMPILE_TEST
depends on ARM && HAS_IOMEM
select TIMER_OF if OF
help
Support for Timer Counter Blocks on Atmel SoCs.
config CLKSRC_EXYNOS_MCT
bool "Exynos multi core timer driver" if COMPILE_TEST
depends on ARM || ARM64
help
Support for Multi Core Timer controller on Exynos SoCs.
config CLKSRC_SAMSUNG_PWM
bool "PWM timer driver for Samsung S3C, S5P" if COMPILE_TEST
depends on HAS_IOMEM
help
This is a new clocksource driver for the PWM timer found in
Samsung S3C, S5P and Exynos SoCs, replacing an earlier driver
for all devicetree enabled platforms. This driver will be
needed only on systems that do not have the Exynos MCT available.
config FSL_FTM_TIMER
bool "Freescale FlexTimer Module driver" if COMPILE_TEST
depends on HAS_IOMEM
select CLKSRC_MMIO
help
Support for Freescale FlexTimer Module (FTM) timer.
config VF_PIT_TIMER
bool
select CLKSRC_MMIO
help
Support for Periodic Interrupt Timer on Freescale Vybrid Family SoCs.
config OXNAS_RPS_TIMER
bool "Oxford Semiconductor OXNAS RPS Timers driver" if COMPILE_TEST
select TIMER_OF
select CLKSRC_MMIO
help
This enables support for the Oxford Semiconductor OXNAS RPS timers.
config SYS_SUPPORTS_SH_CMT
bool
config MTK_TIMER
bool "Mediatek timer driver" if COMPILE_TEST
clocksource: Improve GENERIC_CLOCKEVENTS dependency We regularly run into build errors when a clocksource driver selects CONFIG_TIMER_OF while CONFIG_GENERIC_CLOCKEVENTS is disabled: In file included from drivers/clocksource/timer-of.c:25:0: drivers/clocksource/timer-of.h:35:28: error: field 'clkevt' has incomplete type At the moment, three drivers can show this behavior: ARMV7M_SYSTICK, CLKSRC_ST_LPC and CLKSRC_NPS. We could add further dependencies as we did many times, but I have looked a little bit more at what architectures are left that don't use GENERIC_CLOCKEVENTS, and this shows that there is a better solution. On arch/frv and arch/ia64, we never select CONFIG_GENERIC_CLOCKEVENTS and we also don't use ARCH_USES_GETTIMEOFFSET, which would block the clocksource Kconfig menu. On m68k, some platforms use CONFIG_GENERIC_CLOCKEVENTS, some use ARCH_USES_GETTIMEOFFSET, and some use neither of them. The good news is that there is no configuration that does not set CONFIG_GENERIC_CLOCKEVENTS but that wants to enable any of the Kconfig symbols in the menu, so we can simply replace the dependency with the stricter one. While in theory one could have a clocksource driver without the clockevent infrastructure, this seems unlikely to be relevant in the future any more. We can probably drop some of the other dependencies as well now, e.g. there should generally be no reason to depend on CONFIG_ARM unless the driver uses architecture specific assembly. Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
2017-09-05 15:04:56 +00:00
depends on HAS_IOMEM
select TIMER_OF
select CLKSRC_MMIO
help
Support for Mediatek timer driver.
config SPRD_TIMER
bool "Spreadtrum timer driver" if EXPERT
depends on HAS_IOMEM
depends on (ARCH_SPRD || COMPILE_TEST)
default ARCH_SPRD
select TIMER_OF
help
Enables support for the Spreadtrum timer driver.
config SYS_SUPPORTS_SH_MTU2
bool
config SYS_SUPPORTS_SH_TMU
bool
config SYS_SUPPORTS_EM_STI
bool
clocksource: Add J-Core timer/clocksource driver At the hardware level, the J-Core PIT is integrated with the interrupt controller, but it is represented as its own device and has an independent programming interface. It provides a 12-bit countdown timer, which is not presently used, and a periodic timer. The interval length for the latter is programmable via a 32-bit throttle register whose units are determined by a bus-period register. The periodic timer is used to implement both periodic and oneshot clock event modes; in oneshot mode the interrupt handler simply disables the timer as soon as it fires. Despite its device tree node representing an interrupt for the PIT, the actual irq generated is programmable, not hard-wired. The driver is responsible for programming the PIT to generate the hardware irq number that the DT assigns to it. On SMP configurations, J-Core provides cpu-local instances of the PIT; no broadcast timer is needed. This driver supports the creation of the necessary per-cpu clock_event_device instances. A nanosecond-resolution clocksource is provided using the J-Core "RTC" registers, which give a 64-bit seconds count and 32-bit nanoseconds that wrap every second. The driver converts these to a full-range 32-bit nanoseconds count. Signed-off-by: Rich Felker <dalias@libc.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: devicetree@vger.kernel.org Cc: linux-sh@vger.kernel.org Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Rob Herring <robh+dt@kernel.org> Link: http://lkml.kernel.org/r/b591ff12cc5ebf63d1edc98da26046f95a233814.1476393790.git.dalias@libc.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-10-13 21:51:06 +00:00
config CLKSRC_JCORE_PIT
bool "J-Core PIT timer driver" if COMPILE_TEST
depends on OF
depends on HAS_IOMEM
select CLKSRC_MMIO
help
This enables build of clocksource and clockevent driver for
the integrated PIT in the J-Core synthesizable, open source SoC.
config SH_TIMER_CMT
bool "Renesas CMT timer driver" if COMPILE_TEST
depends on HAS_IOMEM
default SYS_SUPPORTS_SH_CMT
help
This enables build of a clocksource and clockevent driver for
the Compare Match Timer (CMT) hardware available in 16/32/48-bit
variants on a wide range of Mobile and Automotive SoCs from Renesas.
config SH_TIMER_MTU2
bool "Renesas MTU2 timer driver" if COMPILE_TEST
depends on HAS_IOMEM
default SYS_SUPPORTS_SH_MTU2
help
This enables build of a clockevent driver for the Multi-Function
Timer Pulse Unit 2 (MTU2) hardware available on SoCs from Renesas.
This hardware comes with 16-bit timer registers.
config RENESAS_OSTM
bool "Renesas OSTM timer driver" if COMPILE_TEST
select CLKSRC_MMIO
select TIMER_OF
help
Enables the support for the Renesas OSTM.
config SH_TIMER_TMU
bool "Renesas TMU timer driver" if COMPILE_TEST
depends on HAS_IOMEM
default SYS_SUPPORTS_SH_TMU
help
This enables build of a clocksource and clockevent driver for
the 32-bit Timer Unit (TMU) hardware available on a wide range
SoCs from Renesas.
config EM_TIMER_STI
bool "Renesas STI timer driver" if COMPILE_TEST
clocksource: Improve GENERIC_CLOCKEVENTS dependency We regularly run into build errors when a clocksource driver selects CONFIG_TIMER_OF while CONFIG_GENERIC_CLOCKEVENTS is disabled: In file included from drivers/clocksource/timer-of.c:25:0: drivers/clocksource/timer-of.h:35:28: error: field 'clkevt' has incomplete type At the moment, three drivers can show this behavior: ARMV7M_SYSTICK, CLKSRC_ST_LPC and CLKSRC_NPS. We could add further dependencies as we did many times, but I have looked a little bit more at what architectures are left that don't use GENERIC_CLOCKEVENTS, and this shows that there is a better solution. On arch/frv and arch/ia64, we never select CONFIG_GENERIC_CLOCKEVENTS and we also don't use ARCH_USES_GETTIMEOFFSET, which would block the clocksource Kconfig menu. On m68k, some platforms use CONFIG_GENERIC_CLOCKEVENTS, some use ARCH_USES_GETTIMEOFFSET, and some use neither of them. The good news is that there is no configuration that does not set CONFIG_GENERIC_CLOCKEVENTS but that wants to enable any of the Kconfig symbols in the menu, so we can simply replace the dependency with the stricter one. While in theory one could have a clocksource driver without the clockevent infrastructure, this seems unlikely to be relevant in the future any more. We can probably drop some of the other dependencies as well now, e.g. there should generally be no reason to depend on CONFIG_ARM unless the driver uses architecture specific assembly. Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
2017-09-05 15:04:56 +00:00
depends on HAS_IOMEM
default SYS_SUPPORTS_EM_STI
help
This enables build of a clocksource and clockevent driver for
the 48-bit System Timer (STI) hardware available on a SoCs
such as EMEV2 from former NEC Electronics.
ARM: SoC: cleanups for 3.15 These cleanup patches are mainly move stuff around and should all be harmless. They are mainly split out so that other branches can be based on top to avoid conflicts. Notable changes are: * We finally remove all mach/timex.h, after CLOCK_TICK_RATE is no longer used. (Uwe Kleine-König) * The Qualcomm MSM platform is split out into legacy mach-msm and new-style mach-qcom, to allow easier maintainance of the new hardware support without regressions. (Kumar Gala) * A rework of some of the Kconfig logic to simplify multiplatform support (Rob Herring) * Samsung Exynos gets closer to supporting multiplatform (Sachin Kamat and others) * mach-bcm3528 gets merged into mach-bcm (Stephen Warren) * at91 gains some common clock framework support (Alexandre Belloni, Jean-Jacques Hiblot and other French people). -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIVAwUAUz/yOWCrR//JCVInAQLOPBAAwTMkMrD8S8ggz6vfiQHZNdRPAC7NUJ46 +eYKmBVi5d6EdnjNuRElWENsh0ZosSAUFHrXsIC2NdH9sAJ9HOqWNNLymuA59Jo9 HZ/Ze6xQXDPNV7TROPoXuIli/2OCOXyyQHJsfI7h9V3PCx31qo0B5OdCxU0mtXK6 r1giREhnJFwfQMF/FTdnzhalFJoSjWwv/nkpNmQDJKRLKj9GzwQqItqw68gV6RzU Gnt6YK+9xC1B0cfWTFhAm6kbr9i7mvHoMG5tE3no2uuJMn4K7TgeMqOyvPWhmUeB EZi656szT1m5VfRWOqG+7coZO2VM4GO4NI0Xfin3GHllugOYls1il/FAfCPMLiwh RvuOmQGCkLIpdkuHop5QaI/h1EzlHA59nzTjmGf1+wWPsm0CIg08XOD9izQbRnN9 EmRqn1/8POIi17xcWyeMp8LB0APsTI+IflZFaYprEY9VlLLA/Pd+7udULhs8Bq8y 1l6fB6aPZKnDKCBy/PEIR+y+EHFEbwfrx6zm/pxVDX6P5DlQMFWL78pdBoJUa2h8 3pm/bSzNU5OSz1nJMLJv2jBTtnM5BvFgQBUi2qJ9Lr+nUhJXKCJ80kE/nOlXoCIU J952p3OhkYTQQcjuUVQeTXvRUOGB7mKok0pDFZNE6c7faqxTCudMABQq/KbMFstU eE3cH5FyYj4= =GcBb -----END PGP SIGNATURE----- Merge tag 'cleanup-3.15' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc Pull ARM SoC cleanups from Arnd Bergmann: "These cleanup patches are mainly move stuff around and should all be harmless. They are mainly split out so that other branches can be based on top to avoid conflicts. Notable changes are: - We finally remove all mach/timex.h, after CLOCK_TICK_RATE is no longer used (Uwe Kleine-König) - The Qualcomm MSM platform is split out into legacy mach-msm and new-style mach-qcom, to allow easier maintainance of the new hardware support without regressions (Kumar Gala) - A rework of some of the Kconfig logic to simplify multiplatform support (Rob Herring) - Samsung Exynos gets closer to supporting multiplatform (Sachin Kamat and others) - mach-bcm3528 gets merged into mach-bcm (Stephen Warren) - at91 gains some common clock framework support (Alexandre Belloni, Jean-Jacques Hiblot and other French people)" * tag 'cleanup-3.15' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc: (89 commits) ARM: hisi: select HAVE_ARM_SCU only for SMP ARM: efm32: allow uncompress debug output ARM: prima2: build reset code standalone ARM: at91: add PWM clock ARM: at91: move sam9261 SoC to common clk ARM: at91: prepare common clk transition for sam9261 SoC ARM: at91: updated the at91_dt_defconfig with support for the ADS7846 ARM: at91: dt: sam9261: Device Tree support for the at91sam9261ek ARM: at91: dt: defconfig: Added the sam9261 to the list of DT-enabled SOCs ARM: at91: dt: Add at91sam9261 dt SoC support ARM: at91: switch sam9rl to common clock framework ARM: at91/dt: define main clk frequency of at91sam9rlek ARM: at91/dt: define at91sam9rl clocks ARM: at91: prepare common clk transition for sam9rl SoCs ARM: at91: prepare sam9 dt boards transition to common clk ARM: at91: dt: sam9rl: Device Tree for the at91sam9rlek ARM: at91/defconfig: Add the sam9rl to the list of DT-enabled SOCs ARM: at91: Add at91sam9rl DT SoC support ARM: at91: prepare at91sam9rl DT transition ARM: at91/defconfig: refresh at91sam9260_9g20_defconfig ...
2014-04-05 20:51:19 +00:00
config CLKSRC_QCOM
bool "Qualcomm MSM timer" if COMPILE_TEST
depends on ARM
select TIMER_OF
help
This enables the clocksource and the per CPU clockevent driver for the
Qualcomm SoCs.
config CLKSRC_VERSATILE
bool "ARM Versatile (Express) reference platforms clock source" if COMPILE_TEST
depends on GENERIC_SCHED_CLOCK && !ARCH_USES_GETTIMEOFFSET
select TIMER_OF
default y if MFD_VEXPRESS_SYSREG
help
This option enables clock source based on free running
counter available in the "System Registers" block of
ARM Versatile, RealView and Versatile Express reference
platforms.
config CLKSRC_MIPS_GIC
bool
depends on MIPS_GIC
select TIMER_OF
config CLKSRC_TANGO_XTAL
bool "Clocksource for Tango SoC" if COMPILE_TEST
depends on ARM
select TIMER_OF
select CLKSRC_MMIO
help
This enables the clocksource for Tango SoC.
config CLKSRC_PXA
bool "Clocksource for PXA or SA-11x0 platform" if COMPILE_TEST
depends on HAS_IOMEM
select CLKSRC_MMIO
help
This enables OST0 support available on PXA and SA-11x0
platforms.
config H8300_TMR8
bool "Clockevent timer for the H8300 platform" if COMPILE_TEST
depends on HAS_IOMEM
help
This enables the 8 bits timer for the H8300 platform.
config H8300_TMR16
bool "Clockevent timer for the H83069 platform" if COMPILE_TEST
depends on HAS_IOMEM
help
This enables the 16 bits timer for the H8300 platform with the
H83069 CPU.
config H8300_TPU
bool "Clocksource for the H8300 platform" if COMPILE_TEST
depends on HAS_IOMEM
help
This enables the clocksource for the H8300 platform with the
H8S2678 CPU.
config CLKSRC_IMX_GPT
bool "Clocksource using i.MX GPT" if COMPILE_TEST
depends on (ARM || ARM64) && CLKDEV_LOOKUP
select CLKSRC_MMIO
config CLKSRC_IMX_TPM
bool "Clocksource using i.MX TPM" if COMPILE_TEST
clocksource: Improve GENERIC_CLOCKEVENTS dependency We regularly run into build errors when a clocksource driver selects CONFIG_TIMER_OF while CONFIG_GENERIC_CLOCKEVENTS is disabled: In file included from drivers/clocksource/timer-of.c:25:0: drivers/clocksource/timer-of.h:35:28: error: field 'clkevt' has incomplete type At the moment, three drivers can show this behavior: ARMV7M_SYSTICK, CLKSRC_ST_LPC and CLKSRC_NPS. We could add further dependencies as we did many times, but I have looked a little bit more at what architectures are left that don't use GENERIC_CLOCKEVENTS, and this shows that there is a better solution. On arch/frv and arch/ia64, we never select CONFIG_GENERIC_CLOCKEVENTS and we also don't use ARCH_USES_GETTIMEOFFSET, which would block the clocksource Kconfig menu. On m68k, some platforms use CONFIG_GENERIC_CLOCKEVENTS, some use ARCH_USES_GETTIMEOFFSET, and some use neither of them. The good news is that there is no configuration that does not set CONFIG_GENERIC_CLOCKEVENTS but that wants to enable any of the Kconfig symbols in the menu, so we can simply replace the dependency with the stricter one. While in theory one could have a clocksource driver without the clockevent infrastructure, this seems unlikely to be relevant in the future any more. We can probably drop some of the other dependencies as well now, e.g. there should generally be no reason to depend on CONFIG_ARM unless the driver uses architecture specific assembly. Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
2017-09-05 15:04:56 +00:00
depends on ARM && CLKDEV_LOOKUP
select CLKSRC_MMIO
help
Enable this option to use IMX Timer/PWM Module (TPM) timer as
clocksource.
config TIMER_IMX_SYS_CTR
bool "i.MX system counter timer" if COMPILE_TEST
select TIMER_OF
help
Enable this option to use i.MX system counter timer as a
clockevent.
config CLKSRC_ST_LPC
bool "Low power clocksource found in the LPC" if COMPILE_TEST
select TIMER_OF if OF
depends on HAS_IOMEM
select CLKSRC_MMIO
help
Enable this option to use the Low Power controller timer
as clocksource.
config ATCPIT100_TIMER
bool "ATCPIT100 timer driver"
depends on NDS32 || COMPILE_TEST
depends on HAS_IOMEM
select TIMER_OF
default NDS32
help
This option enables support for the Andestech ATCPIT100 timers.
config RISCV_TIMER
bool "Timer for the RISC-V platform"
depends on GENERIC_SCHED_CLOCK && RISCV
default y
select TIMER_PROBE
select TIMER_OF
help
This enables the per-hart timer built into all RISC-V systems, which
is accessed via both the SBI and the rdcycle instruction. This is
required for all RISC-V systems.
config CSKY_MP_TIMER
bool "SMP Timer for the C-SKY platform" if COMPILE_TEST
depends on CSKY
select TIMER_OF
help
Say yes here to enable C-SKY SMP timer driver used for C-SKY SMP
system.
csky,mptimer is not only used in SMP system, it also could be used in
single core system. It's not a mmio reg and it uses mtcr/mfcr instruction.
config GX6605S_TIMER
bool "Gx6605s SOC system timer driver" if COMPILE_TEST
depends on CSKY
select CLKSRC_MMIO
select TIMER_OF
help
This option enables support for gx6605s SOC's timer.
config MILBEAUT_TIMER
bool "Milbeaut timer driver" if COMPILE_TEST
depends on OF
depends on ARM
select TIMER_OF
select CLKSRC_MMIO
help
Enables the support for Milbeaut timer driver.
config INGENIC_TIMER
bool "Clocksource/timer using the TCU in Ingenic JZ SoCs"
default MACH_INGENIC
depends on MIPS || COMPILE_TEST
depends on COMMON_CLK
select MFD_SYSCON
select TIMER_OF
select IRQ_DOMAIN
help
Support for the timer/counter unit of the Ingenic JZ SoCs.
config MICROCHIP_PIT64B
bool "Microchip PIT64B support"
depends on OF || COMPILE_TEST
select CLKSRC_MMIO
help
This option enables Microchip PIT64B timer for Atmel
based system. It supports the oneshot, the periodic
modes and high resolution. It is used as a clocksource
and a clockevent.
endmenu