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https://git.linaro.org/people/daniel.lezcano/linux into timers/core
Pull clocksource/events updates from Daniel Lezcano:
- Refactor resource allocation on the Exynos_mct driver without
functional changes (Marek Szyprowski)
- Add imx8ulp compatible string for NPX TPM driver (Jacky Bai)
- Fix comma introduced by error by replacing it by the initial
semicolon on the Exynos_mct (Will Deacon)
- Add OSTM driver support on Renesas. The reset line must be
deasserted before accessing the registers. This change depends on an
external change resulting in a shared immutable branch
'reset/of-get-optional-exclusive' from
git://git.pengutronix.de/pza/linux (Biju Das)
- Make the OSTM Kconfig option visible to user in order to let him
disable it when ARM architected timers is enabled (Biju Das)
- Tag two variables on iMX sysctr _ro_afterinit (Peng Fan)
- Set the cpumask to cpu_possible_mask in order to have full benefit
of the DYNIRQ flag on iMX sysctr (Peng Fan)
- Tag __maybe_unused a variable in the Pistachio timer driver in order
to fix a warning reported by the kernel test robot (Drew Fustini)
- Add MStar MSC313e timer support and the ssd20xd-based variant, as
well as the DT bindings (Romain Perier)
- Remove the incompatible compatible string for the rk3066 (Johan
Jonker)
- Fix dts_check warnings on the cadence ttc driver by adding the power
domain bindings (Michal Simek)
Link: https://lore.kernel.org/lkml/e093c706-c98d-29ee-0102-78b6d41c6164@linaro.org
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On SSD20X family SoCs the timers are connected to a 432MHz clock instead
of 12MHz that all the previous chips used. There is no way to reduce or
divide these clocks in the clktree yet as we do not know exactly where
the 432MHz clock comes from but it is enabled at boot.
The SSD20X timers have an input clock divider within the timer itself
to configure the frequency. timer0 is preconfigured at power up to run
at 12MHz so it is backwards compatible and doesn't need special handling
right now. timer1 and timer2 run at 432Mhz at power up so are not
backward compatible.
This commit adds support for the input clock divider register and sets
timer1 and timer2 to run at 48Mhz for clockevents.
Signed-off-by: Romain Perier <romain.perier@gmail.com>
Link: https://lore.kernel.org/r/20211217195727.8955-3-romain.perier@gmail.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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The MSC313e-compatible SoCs have 3 timer hardware blocks. All of these
are free running 32-bit increasing counters and can generate interrupts.
Based onto a maximum value register, each timer can either count from 0
to max, one time then stop (which generates interrupts) or can count
from 0 to max and then roll. This commit adds basic support for these
timers, the first timer block being used as clocksource/sched_clock
and delay, while the others will be used as clockevents.
Signed-off-by: Romain Perier <romain.perier@gmail.com>
Co-developed-by: Daniel Palmer <daniel@0x0f.com>
Signed-off-by: Daniel Palmer <daniel@0x0f.com>
Link: https://lore.kernel.org/r/20211217195727.8955-2-romain.perier@gmail.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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Variable 'overflow' set but not used, but this is the intended behavior.
The hardware only updates the counter register after the overflow
register read. However, the value of overflow is not actually needed.
Link: https://lore.kernel.org/lkml/202111200402.afQsussU-lkp@intel.com/
Reported-by: kernel test robot <lkp@intel.com>
Suggested-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Drew Fustini <dfustini@baylibre.com>
Link: https://lore.kernel.org/r/20211123192524.1038304-1-dfustini@baylibre.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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The syctr interrupt could set the affinity to any cores in the
SoC. However, the default affinity is set to cpu 0.
This timer will be used as broadcast timer on all the i.MX
SoCs. Because DYNIRQ flag is set, the core time framework will runtime
set the interrupt affinity to the cores that needs to wake up and the
cpumask will runtime set to the core that will be wake up. So even the
sysctr initialization use cpumask 0, there is no issue, the current
patch is just use cpu_possible_mask to show the fact that the timer
supports routed to all the cpu cores and nothing else.
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/20211201125030.2307746-2-peng.fan@oss.nxp.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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erratum_set_next_event_generic()
With some specific kernel configuration and Clang, the kernel fails
to like with something like:
ld.lld: error: undefined symbol: __compiletime_assert_200
>>> referenced by arch_timer.h:156 (./arch/arm64/include/asm/arch_timer.h:156)
>>> clocksource/arm_arch_timer.o:(erratum_set_next_event_generic) in archive drivers/built-in.a
ld.lld: error: undefined symbol: __compiletime_assert_197
>>> referenced by arch_timer.h:133 (./arch/arm64/include/asm/arch_timer.h:133)
>>> clocksource/arm_arch_timer.o:(erratum_set_next_event_generic) in archive drivers/built-in.a
make: *** [Makefile:1161: vmlinux] Error 1
These are due to the BUILD_BUG() macros contained in the low-level
accessors (arch_timer_reg_{write,read}_cp15) being emitted, as the
access type wasn't known at compile time.
Fix this by making erratum_set_next_event_generic() __force_inline,
resulting in the 'access' parameter to be resolved at compile time,
similarly to what is already done for set_next_event().
Fixes: 4775bc63f880 ("Add build-time guards for unhandled register accesses")
Reported-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20211117113532.3895208-1-maz@kernel.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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The driver refuses to probe with -EINVAL since the commit 5d9814df0aec
("clocksource/drivers/dw_apb_timer_of: Add error handling if no clock
available").
Before the driver used to probe successfully if either "clock-freq" or
"clock-frequency" properties has been specified in the device tree.
That commit changed
if (A && B)
panic("No clock nor clock-frequency property");
into
if (!A && !B)
return 0;
That's a bug: the reverse of `A && B` is '!A || !B', not '!A && !B'
Signed-off-by: Vadim V. Vlasov <vadim.vlasov@elpitech.ru>
Signed-off-by: Alexey Sheplyakov <asheplyakov@basealt.ru>
Fixes: 5d9814df0aec56a6 ("clocksource/drivers/dw_apb_timer_of: Add error handling if no clock available").
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vadim V. Vlasov <vadim.vlasov@elpitech.ru>
Acked-by: Dinh Nguyen <dinguyen@kernel.org>
Link: https://lore.kernel.org/r/20211109153401.157491-1-asheplyakov@basealt.ru
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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The variables 'sys_ctr_base' and 'cmpcr' are not be updated after
init, so mark them as __ro_after_init.
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20211201125030.2307746-1-peng.fan@oss.nxp.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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As RZ/G2L uses the ARM Architected Timer as system timer, enabling
the OSTM is not mandatory.
Make RENESAS_OSTM symbol visible, so that user can enable it
when needed.
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20211112184413.4391-5-biju.das.jz@bp.renesas.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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RZ/G2L SoC has Generic Timer Module(a.k.a OSTM) which needs to
deassert the reset line before accessing any registers.
This patch adds an entry point for RZ/G2L so that we can deassert
the reset line in probe callback.
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20211112184413.4391-4-biju.das.jz@bp.renesas.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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git://git.pengutronix.de/pza/linux into timers/drivers/next
"Add optional variant of of_reset_control_get_exclusive(). If the
requested reset is not specified in the device tree, this function
returns NULL instead of an error."
This dependency is needed for the Generic Timer Module (a.k.a OSTM)
support for RZ/G2L.
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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Commit ae460fd9164b ("clocksource/drivers/exynos_mct: Prioritise Arm
arch timer on arm64") changed the rating of the MCT clockevents device
to be lower than the Arm architected timer and, in the process, replaced
a semicolon with a comma thanks to a silly copy-paste error.
Put the semicolon back so that the code looks more idiomatic and resolve
the SUSPECT_COMMA_SEMICOLON warning from checkpatch at the same time.
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Will Deacon <will@kernel.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20211103164804.30182-1-will@kernel.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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Move interrupts allocation from exynos4_timer_resources() into separate
function together with the interrupt number parsing code from
mct_init_dt(), so the code for managing interrupts is kept together.
While touching exynos4_timer_resources() function, move of_iomap() to it.
No functional changes.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Tested-by: Chanwoo Choi <cw00.choi@samsung.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Link: https://lore.kernel.org/r/20211101193531.15078-2-semen.protsenko@linaro.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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Pull KVM updates from Paolo Bonzini:
"ARM:
- More progress on the protected VM front, now with the full fixed
feature set as well as the limitation of some hypercalls after
initialisation.
- Cleanup of the RAZ/WI sysreg handling, which was pointlessly
complicated
- Fixes for the vgic placement in the IPA space, together with a
bunch of selftests
- More memcg accounting of the memory allocated on behalf of a guest
- Timer and vgic selftests
- Workarounds for the Apple M1 broken vgic implementation
- KConfig cleanups
- New kvmarm.mode=none option, for those who really dislike us
RISC-V:
- New KVM port.
x86:
- New API to control TSC offset from userspace
- TSC scaling for nested hypervisors on SVM
- Switch masterclock protection from raw_spin_lock to seqcount
- Clean up function prototypes in the page fault code and avoid
repeated memslot lookups
- Convey the exit reason to userspace on emulation failure
- Configure time between NX page recovery iterations
- Expose Predictive Store Forwarding Disable CPUID leaf
- Allocate page tracking data structures lazily (if the i915 KVM-GT
functionality is not compiled in)
- Cleanups, fixes and optimizations for the shadow MMU code
s390:
- SIGP Fixes
- initial preparations for lazy destroy of secure VMs
- storage key improvements/fixes
- Log the guest CPNC
Starting from this release, KVM-PPC patches will come from Michael
Ellerman's PPC tree"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (227 commits)
RISC-V: KVM: fix boolreturn.cocci warnings
RISC-V: KVM: remove unneeded semicolon
RISC-V: KVM: Fix GPA passed to __kvm_riscv_hfence_gvma_xyz() functions
RISC-V: KVM: Factor-out FP virtualization into separate sources
KVM: s390: add debug statement for diag 318 CPNC data
KVM: s390: pv: properly handle page flags for protected guests
KVM: s390: Fix handle_sske page fault handling
KVM: x86: SGX must obey the KVM_INTERNAL_ERROR_EMULATION protocol
KVM: x86: On emulation failure, convey the exit reason, etc. to userspace
KVM: x86: Get exit_reason as part of kvm_x86_ops.get_exit_info
KVM: x86: Clarify the kvm_run.emulation_failure structure layout
KVM: s390: Add a routine for setting userspace CPU state
KVM: s390: Simplify SIGP Set Arch handling
KVM: s390: pv: avoid stalls when making pages secure
KVM: s390: pv: avoid stalls for kvm_s390_pv_init_vm
KVM: s390: pv: avoid double free of sida page
KVM: s390: pv: add macros for UVC CC values
s390/mm: optimize reset_guest_reference_bit()
s390/mm: optimize set_guest_storage_key()
s390/mm: no need for pte_alloc_map_lock() if we know the pmd is present
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer updates from Thomas Gleixner:
"Time, timers and timekeeping updates:
- No core updates
- No new clocksource/event driver
- A large rework of the ARM architected timer driver to prepare for
the support of the upcoming ARMv8.6 support
- Fix Kconfig options for Exynos MCT, Samsung PWM and TI DM timers
- Address a namespace collison in the ARC sp804 timer driver"
* tag 'timers-core-2021-10-31' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
clocksource/drivers/timer-ti-dm: Select TIMER_OF
clocksource/drivers/exynosy: Depend on sub-architecture for Exynos MCT and Samsung PWM
clocksource/drivers/arch_arm_timer: Move workaround synchronisation around
clocksource/drivers/arm_arch_timer: Fix masking for high freq counters
clocksource/drivers/arm_arch_timer: Drop unnecessary ISB on CVAL programming
clocksource/drivers/arm_arch_timer: Remove any trace of the TVAL programming interface
clocksource/drivers/arm_arch_timer: Work around broken CVAL implementations
clocksource/drivers/arm_arch_timer: Advertise 56bit timer to the core code
clocksource/drivers/arm_arch_timer: Move MMIO timer programming over to CVAL
clocksource/drivers/arm_arch_timer: Fix MMIO base address vs callback ordering issue
clocksource/drivers/arm_arch_timer: Move drop _tval from erratum function names
clocksource/drivers/arm_arch_timer: Move system register timer programming over to CVAL
clocksource/drivers/arm_arch_timer: Extend write side of timer register accessors to u64
clocksource/drivers/arm_arch_timer: Drop CNT*_TVAL read accessors
clocksource/arm_arch_timer: Add build-time guards for unhandled register accesses
clocksource/drivers/arc_timer: Eliminate redefined macro error
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When building OMAP_DM_TIMER without TIMER_OF, there are orphan sections
due to the use of TIMER_OF_DELCARE() without CONFIG_TIMER_OF. Select
CONFIG_TIMER_OF when enaling OMAP_DM_TIMER:
arm-linux-gnueabi-ld: warning: orphan section `__timer_of_table' from `drivers/clocksource/timer-ti-dm-systimer.o' being placed in section `__timer_of_table'
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/202108282255.tkdt4ani-lkp@intel.com/
Cc: Tony Lindgren <tony@atomide.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Keerthy <j-keerthy@ti.com>
Cc: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Cc: Ladislav Michl <ladis@linux-mips.org>
Cc: Grygorii Strashko <grygorii.strashko@ti.com>
Cc: linux-omap@vger.kernel.org
Fixes: 52762fbd1c47 ("clocksource/drivers/timer-ti-dm: Add clockevent and clocksource support")
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20210828175747.3777891-1-keescook@chromium.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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Samsung PWM
The Exynos MCT and Samsung PWM Timer clocksource drivers are not usable
on anything else than Samsung Exynos, S3C or S5P SoC platforms. These
are integral parts of a SoC. Even though the drivers are not user
selectable, still document the hardware architecture explicitly with
depends on ARCH_EXYNOS and others. This also serves a purpose of
documenting use-case, if someone ever wonders whether to select the
driver for his platform. No functional change, because drivers are
already selected by the platform described in depends. We follow similar
approach also for other SoC-specific drivers.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20211021063500.39314-1-krzysztof.kozlowski@canonical.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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The branch is a stable branch shared with ARM maintainers for the
first 13th patches of the series:
It is based on v5.14-rc3.
As stated by the changelog:
" [... ] enabling ARMv8.6 support for timer subsystem, and was prompted by a
discussion with Oliver around the fact that an ARMv8.6 implementation
must have a 1GHz counter, which leads to a number of things to break
in the timer code:
- the counter rollover can come pretty quickly as we only advertise a
56bit counter,
- the maximum timer delta can be remarkably small, as we use the
countdown interface which is limited to 32bit...
Thankfully, there is a way out: we can compute the minimal width of
the counter based on the guarantees that the architecture gives us,
and we can use the 64bit comparator interface instead of the countdown
to program the timer.
Finally, we start making use of the ARMv8.6 ECV features by switching
accesses to the counters to a self-synchronising register, removing
the need for an ISB. Hopefully, implementations will *not* just stick
an invisible ISB there...
A side effect of the switch to CVAL is that XGene-1 breaks. I have
added a workaround to keep it alive.
I have added Oliver's original patch[0] to the series and tweaked a
couple of things. Blame me if I broke anything.
The whole things has been tested on Juno (sysreg + MMIO timers),
XGene-1 (broken sysreg timers), FVP (FEAT_ECV, CNT*CTSS_EL0).
"
Link: https://lore.kernel.org/r/20211017124225.3018098-1-maz@kernel.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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Unfortunately, the architecture provides no means to determine the bit
width of the system counter. However, we do know the following from the
specification:
- the system counter is at least 56 bits wide
- Roll-over time of not less than 40 years
To date, the arch timer driver has depended on the first property,
assuming any system counter to be 56 bits wide and masking off the rest.
However, combining a narrow clocksource mask with a high frequency
counter could result in prematurely wrapping the system counter by a
significant margin. For example, a 56 bit wide, 1GHz system counter
would wrap in a mere 2.28 years!
This is a problem for two reasons: v8.6+ implementations are required to
provide a 64 bit, 1GHz system counter. Furthermore, before v8.6,
implementers may select a counter frequency of their choosing.
Fix the issue by deriving a valid clock mask based on the second
property from above. Set the floor at 56 bits, since we know no system
counter is narrower than that.
[maz: fixed width computation not to lose the last bit, added
max delta generation for the timer]
Suggested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Oliver Upton <oupton@google.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210807191428.3488948-1-oupton@google.com
Link: https://lore.kernel.org/r/20211017124225.3018098-13-maz@kernel.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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interface
TVAL usage is now long gone, get rid of the leftovers.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211017124225.3018098-11-maz@kernel.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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The Applied Micro XGene-1 SoC has a busted implementation of the
CVAL register: it looks like it is based on TVAL instead of the
other way around. The net effect of this implementation blunder
is that the maximum deadline you can program in the timer is
32bit wide.
Use a MIDR check to notice the broken CPU, and reduce the width
of the timer to 32bit.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211017124225.3018098-10-maz@kernel.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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Proudly tell the code code that we have a timer able to handle
56 bits deltas.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211017124225.3018098-9-maz@kernel.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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Similarily to the sysreg-based timer, move the MMIO over to using
the CVAL registers instead of TVAL. Note that there is no warranty
that the 64bit MMIO access will be atomic, but the timer is always
disabled at the point where we program CVAL.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211017124225.3018098-8-maz@kernel.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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ordering issue
The MMIO timer base address gets published after we have registered
the callbacks and the interrupt handler, which is... a bit dangerous.
Fix this by moving the base address publication to the point where
we register the timer, and expose a pointer to the timer structure
itself rather than a naked value.
Reviewed-by: Oliver Upton <oupton@google.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211017124225.3018098-7-maz@kernel.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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The '_tval' name in the erratum handling function names doesn't
make much sense anymore (and they were using CVAL the first place).
Drop the _tval tag.
Reviewed-by: Oliver Upton <oupton@google.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211017124225.3018098-6-maz@kernel.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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over to CVAL
In order to cope better with high frequency counters, move the
programming of the timers from the countdown timer (TVAL) over
to the comparator (CVAL).
The programming model is slightly different, as we now need to
read the current counter value to have an absolute deadline
instead of a relative one.
There is a small overhead to this change, which we will address
in the following patches.
Reviewed-by: Oliver Upton <oupton@google.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211017124225.3018098-5-maz@kernel.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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accessors to u64
The various accessors for the timer sysreg and MMIO registers are
currently hardwired to 32bit. However, we are about to introduce
the use of the CVAL registers, which require a 64bit access.
Upgrade the write side of the accessors to take a 64bit value
(the read side is left untouched as we don't plan to ever read
back any of these registers).
No functional change expected.
Reviewed-by: Oliver Upton <oupton@google.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211017124225.3018098-4-maz@kernel.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
|
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The arch timer driver never reads the various TVAL registers, only
writes to them. It is thus pointless to provide accessors
for them and to implement errata workarounds.
Drop these read-side accessors, and add a couple of BUG() statements
for the time being. These statements will be removed further down
the line.
Reviewed-by: Oliver Upton <oupton@google.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211017124225.3018098-3-maz@kernel.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
|
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accesses
As we are about to change the registers that are used by the driver,
start by adding build-time checks to ensure that we always handle
all registers and access modes.
Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211017124225.3018098-2-maz@kernel.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
|
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In drivers/clocksource/, 3 drivers use "TIMER_CTRL_IE" with 3 different
values. Two of them (mps2-timer.c and timer-sp804.c/timer-sp.h) are
localized and left unmodifed.
One of them uses a shared header file (<soc/arc/timers.h>), which is
what is causing the "redefined" warnings, so change the macro name in
that driver only. Also change the TIMER_CTRL_NH macro name.
Both macro names are prefixed with "ARC_" to reduce the likelihood
of future name collisions.
In file included from ../drivers/clocksource/timer-sp804.c:24:
../drivers/clocksource/timer-sp.h:25: error: "TIMER_CTRL_IE" redefined [-Werror]
25 | #define TIMER_CTRL_IE (1 << 5) /* VR */
../include/soc/arc/timers.h:20: note: this is the location of the previous definition
20 | #define TIMER_CTRL_IE (1 << 0) /* Interrupt when Count reaches limit */
Fixes: b26c2e3823ba ("ARC: breakout timer include code into separate header")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: linux-snps-arc@lists.infradead.org
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Shahab Vahedi <Shahab.Vahedi@synopsys.com>
Acked-by: Vineet Gupta <vgupta@kernel.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210924020825.20317-1-rdunlap@infradead.org
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The RISC-V hypervisor specification doesn't have any virtual timer
feature.
Due to this, the guest VCPU timer will be programmed via SBI calls.
The host will use a separate hrtimer event for each guest VCPU to
provide timer functionality. We inject a virtual timer interrupt to
the guest VCPU whenever the guest VCPU hrtimer event expires.
This patch adds guest VCPU timer implementation along with ONE_REG
interface to access VCPU timer state from user space.
Signed-off-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux
Pull MIPS updates from Thomas Bogendoerfer:
- converted Pistachio platform to use MIPS generic kernel
- fixes and cleanups
* tag 'mips_5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux: (29 commits)
MIPS: Malta: fix alignment of the devicetree buffer
MIPS: ingenic: Unconditionally enable clock of CPU #0
MIPS: mscc: ocelot: mark the phy-mode for internal PHY ports
MIPS: mscc: ocelot: disable all switch ports by default
MAINTAINERS: adjust PISTACHIO SOC SUPPORT after its retirement
MIPS: Return true/false (not 1/0) from bool functions
MIPS: generic: Return true/false (not 1/0) from bool functions
MIPS: Make a alias for pistachio_defconfig
MIPS: Retire MACH_PISTACHIO
MIPS: config: generic: Add config for Marduk board
pinctrl: pistachio: Make it as an option
phy: pistachio-usb: Depend on MIPS || COMPILE_TEST
clocksource/drivers/pistachio: Make it selectable for MIPS
clk: pistachio: Make it selectable for generic MIPS kernel
MIPS: DTS: Pistachio add missing cpc and cdmm
MIPS: generic: Allow generating FIT image for Marduk board
MIPS: locking/atomic: Fix atomic{_64,}_sub_if_positive
MIPS: loongson2ef: don't build serial.o unconditionally
MIPS: Replace deprecated CPU-hotplug functions.
MIPS: Alchemy: Fix spelling contraction "cant" -> "can't"
...
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git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux
Pull hyperv updates from Wei Liu:
- make Hyper-V code arch-agnostic (Michael Kelley)
- fix sched_clock behaviour on Hyper-V (Ani Sinha)
- fix a fault when Linux runs as the root partition on MSHV (Praveen
Kumar)
- fix VSS driver (Vitaly Kuznetsov)
- cleanup (Sonia Sharma)
* tag 'hyperv-next-signed-20210831' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux:
hv_utils: Set the maximum packet size for VSS driver to the length of the receive buffer
Drivers: hv: Enable Hyper-V code to be built on ARM64
arm64: efi: Export screen_info
arm64: hyperv: Initialize hypervisor on boot
arm64: hyperv: Add panic handler
arm64: hyperv: Add Hyper-V hypercall and register access utilities
x86/hyperv: fix root partition faults when writing to VP assist page MSR
hv: hyperv.h: Remove unused inline functions
drivers: hv: Decouple Hyper-V clock/timer code from VMbus drivers
x86/hyperv: add comment describing TSC_INVARIANT_CONTROL MSR setting bit 0
Drivers: hv: Move Hyper-V misc functionality to arch-neutral code
Drivers: hv: Add arch independent default functions for some Hyper-V handlers
Drivers: hv: Make portions of Hyper-V init code be arch neutral
x86/hyperv: fix for unwanted manipulation of sched_clock when TSC marked unstable
asm-generic/hyperv: Add missing #include of nmi.h
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git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc
Pull ARM SoC driver updates from Arnd Bergmann:
"These are updates for drivers that are tied to a particular SoC,
including the correspondig device tree bindings:
- A couple of reset controller changes for unisoc, uniphier, renesas
and zte platforms
- memory controller driver fixes for omap and tegra
- Rockchip io domain driver updates
- Lots of updates for qualcomm platforms, mostly touching their
firmware and power management drivers
- Tegra FUSE and firmware driver updateѕ
- Support for virtio transports in the SCMI firmware framework
- cleanup of ixp4xx drivers, towards enabling multiplatform support
and bringing it up to date with modern platforms
- Minor updates for keystone, mediatek, omap, renesas"
* tag 'drivers-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (96 commits)
reset: simple: remove ZTE details in Kconfig help
soc: rockchip: io-domain: Remove unneeded semicolon
soc: rockchip: io-domain: add rk3568 support
dt-bindings: power: add rk3568-pmu-io-domain support
bus: ixp4xx: return on error in ixp4xx_exp_probe()
soc: renesas: Prefer memcpy() over strcpy()
firmware: tegra: Stop using seq_get_buf()
soc/tegra: fuse: Enable fuse clock on suspend for Tegra124
soc/tegra: fuse: Add runtime PM support
soc/tegra: fuse: Clear fuse->clk on driver probe failure
soc/tegra: pmc: Prevent racing with cpuilde driver
soc/tegra: bpmp: Remove unused including <linux/version.h>
dt-bindings: soc: ti: pruss: Add dma-coherent property
soc: ti: Remove pm_runtime_irq_safe() usage for smartreflex
soc: ti: pruss: Enable support for ICSSG subsystems on K3 AM64x SoCs
dt-bindings: soc: ti: pruss: Update bindings for K3 AM64x SoCs
firmware: arm_scmi: Use WARN_ON() to check configured transports
firmware: arm_scmi: Fix boolconv.cocci warnings
soc: mediatek: mmsys: Fix missing UFOE component in mt8173 table routing
soc: mediatek: mmsys: add MT8365 support
...
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Just pass bool flags from the different initcalls and use the
flags to set the right pointers. This results in less pointers
passed around in init.
Cc: Cédric Le Goater <clg@kaod.org>
Cc: Joel Stanley <joel@jms.id.au>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210724224424.2085404-1-linus.walleij@linaro.org
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mtk_syst_clkevt_shutdown is called after irq disabled in suspend flow,
clear any pending systimer irq when shutdown to avoid suspend aborted
due to timer irq pending
Also as for systimer in mediatek socs, there must be firstly enable
timer before clear systimer irq
Fixes: e3af677607d9("clocksource/drivers/timer-mediatek: Add support for system timer")
Signed-off-by: Fengquan Chen <fengquan.chen@mediatek.com>
Tested-by: Hsin-Yi Wang <hsinyi@chromium.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/1617960162-1988-2-git-send-email-Fengquan.Chen@mediatek.com
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Use "FIELD_GET()" and "FIELD_PREP()" to simplify the code.
[dlezcano] : Changed title
Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
Reviewed-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/1627638188-116163-1-git-send-email-zhouyanjie@wanyeetech.com
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source channel
If CMT instance has at least two channels, one channel will be used
as a clock source and another one used as a clock event device.
In that case, IRQ is not requested for clock source channel so
sh_cmt_clock_event_program_verify() might work incorrectly.
Besides, when a channel is only used for clock source, don't need to
re-set the next match_value since it should be maximum timeout as
it still is.
On the other hand, due to no IRQ, total_cycles is not counted up
when reaches compare match time (timer counter resets to zero),
so sh_cmt_clocksource_read() returns unexpected value.
Therefore, use 64-bit clocksoure's mask for 32-bit or 16-bit variants
will also lead to wrong delta calculation. Hence, this mask should
correspond to timer counter width, and above function just returns
the raw value of timer counter register.
Fixes: bfa76bb12f23 ("clocksource: sh_cmt: Request IRQ for clock event device only")
Fixes: 37e7742c55ba ("clocksource/drivers/sh_cmt: Fix clocksource width for 32-bit machines")
Signed-off-by: Phong Hoang <phong.hoang.wz@renesas.com>
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210422123443.73334-1-niklas.soderlund+renesas@ragnatech.se
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The "mct_tick" is a per-cpu clockevents device. Set the
CLOCK_EVT_FEAT_PERCPU feature to prevent e.g. mct_tick0 being unsafely
designated as the global broadcast timer and instead treat the device as
a per-cpu wakeup timer.
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Will Deacon <will@kernel.org>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210608154341.10794-3-will@kernel.org
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All arm64 CPUs feature an architected timer, which offers a relatively
low-latency interface to a per-cpu clocksource and timer. For the most
part, using this interface is a no-brainer, with the exception of SoCs
where it cannot be used to wake up from deep idle state (i.e.
CLOCK_EVT_FEAT_C3STOP is set).
On the contrary, the Exynos MCT is extremely slow to access yet can be
used as a wakeup source. In preparation for using the Exynos MCT as a
potential wakeup timer for the Arm architected timer, reduce its ratings
so that the architected timer is preferred.
This effectively reverts the decision made in 6282edb72bed
("clocksource/drivers/exynos_mct: Increase priority over ARM arch timer")
for arm64, as the reasoning for the original change was to work around
a 32-bit SoC design.
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Will Deacon <will@kernel.org>
Tested-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com> # exynos-5422
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210608154341.10794-2-will@kernel.org
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So it will be avilable for generic MIPS kernel.
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
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This rewrites the IXP4xx watchdog driver as follows:
- Spawn the watchdog driver as a platform device from the timer
driver. It's one device in the hardware, and the fact that
Linux splits the handling into two different devices is
a Linux pecularity, and thus it becomes a Linux pecularity
to spawn a separate watchdog driver.
- Spawn the watchdog driver from the timer driver at probe().
This is well after the timer driver as actually registered and
started and we know the register base is available.
- Instead of looping back callbacks to the timer drivers for all
watchdog calls, pass the register base to the watchdog driver
and manage the registers there. The two drivers aren't even
interested in the same register so the spinlock is totally
surplus, delete it.
- Replace pretty much all of the content in the watchdog driver
with a simple, modern watchdog driver utilizing the watchdog
core instead of registering its own misc device and ioctl()
handling.
- Drop module parameters as the same already exist in the
watchdog core.
What remains is a slim elegant (IMO) watchdog driver using the
watchdog core, spawning from device tree or boardfile alike.
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
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Hyper-V clock/timer code in hyperv_timer.c is mostly independent from
other VMbus drivers, but building for ARM64 without hyperv_timer.c
shows some remaining entanglements. A default implementation of
hv_read_reference_counter can just read a Hyper-V synthetic register
and be independent of hyperv_timer.c, so move this code out and into
hv_common.c. Then it can be used by the timesync driver even if
hyperv_timer.c isn't built on a particular architecture. If
hyperv_timer.c *is* built, it can override with a faster implementation.
Also provide stubs for stimer functions called by the VMbus driver when
hyperv_timer.c isn't built.
No functional changes.
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1626220906-22629-1-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux
Pull clk updates from Stephen Boyd:
"This round has a diffstat dominated by Qualcomm clk drivers. Honestly
though that's just a bunch of data so the diffstat reflects that.
Looking beyond that there's just a bunch of updates all around in
various clk drivers. Renesas and NXP (for i.MX) are two SoC vendors
that have a lot of patches in here.
Overall the driver changes look to be mostly enabling more clks and
non-critical fixes that we could hold until the next merge window.
I'm especially excited about the series from Arnd that graduates
clkdev to be the only implementation of clk_get() and clk_put().
That's a good step in the right direction to migreate eveerything over
to the common clk framework. Now we don't have to worry about clkdev
specific details, they're just part of the clk API now.
Core:
- clkdev is now the only option, i.e. clk_get()/clk_put() is
implemented in only one place in the kernel instead of in
drivers/clk/clkdev.c and in architectures that want their own
implementation
New Drivers:
- Texas Instruments' LMK04832 Ultra Low-Noise JESD204B Compliant
Clock Jitter Cleaner With Dual Loop PLLs
- Qualcomm MDM9607 GCC
- Qualcomm SC8180X display clks
- Qualcomm SM6125 GCC
- Qualcomm SM8250 CAMCC (camera)
- Renesas RZ/G2L SoC
- Hisilicon hi3559A SoC
Updates:
- Stop using clock-output-names in ST clk drivers (yay!)
- Support secure mode of STM32MP1 SoCs
- Improve clock support for Actions S500 SoC
- duty cycle setting support on qcom clks
- Add TI am33xx spread spectrum clock support
- Use determine_rate() for the Amlogic pll ops instead of
round_rate()
- Restrict Amlogic gp0/1 and audio plls range on g12a/sm1
- Improve Amlogic axg-audio controller error on deferral
- Add NNA clocks on Amlogic g12a
- Reduce memory footprint of Rockchip PLL rate tables
- A fix for the newly added Rockchip rk3568 clk driver
- Exported clock for the newly added Rockchip video decoder
- Remove audio ipg clock from i.MX8MP
- Remove deprecated legacy clock binding for i.MX SCU clock driver
- Use common clk-imx8qxp for both i.MX8QXP and i.MX8QM
- Add multiple clocks to clk-imx8qxp driver (enet, hdmi, lcdif,
audio, parallel interface)
- Add dedicated clock ops for i.MX paralel interface
- Different fixes for clocks controlled by ATF on i.MX SoCs
- Add A53/A72 frequency scaling support i.MX clk-scu driver
- Add special case for DCSS clock on suspend for i.MX clk-scu driver
- Add parent save/restore on suspend/resume to i.MX clk-scu driver
- Skip runtime PM enablement for CPU clocks in i.MX clk-scu driver
- Remove the sys1_pll/sys2_pll clock gates for i.MX8MQ and their
bindings
- Tegra clk driver no longer deasserts resets on clk_enable as it
gets in the way of certain power-up sequences
- Fix compile testing for Tegra clk driver
- One patch to fix a divider on the Allwinner v3s Audio PLL
- Add support for CPU core clock boost modes on Renesas R-Car Gen3
- Add ISPCS (Image Signal Processor) clocks on Renesas R-Car V3U
- Switch SH/R-Mobile and R-Car "DIV6" clocks to .determine_rate() and
improve support for multiple parents
- Switch Renesas RZ/N1 divider clocks to .determine_rate()
- Add ZA2 (Audio Clock Generator) clock on Renesas R-Car D3
- Convert ar7 to common clk framework
- Convert ralink to common clk framework"
* tag 'clk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux: (161 commits)
clk: zynqmp: Handle divider specific read only flag
clk: zynqmp: Use firmware specific mux clock flags
clk: zynqmp: Use firmware specific divider clock flags
clk: zynqmp: Use firmware specific common clock flags
clk: lmk04832: Use of match table
clk: lmk04832: Depend on SPI
clk: stm32mp1: new compatible for secure RCC support
dt-bindings: clock: stm32mp1 new compatible for secure rcc
dt-bindings: reset: add MCU HOLD BOOT ID for SCMI reset domains on stm32mp15
dt-bindings: reset: add IDs for SCMI reset domains on stm32mp15
dt-bindings: clock: add IDs for SCMI clocks on stm32mp15
reset: stm32mp1: remove stm32mp1 reset
clk: hisilicon: Add clock driver for hi3559A SoC
dt-bindings: Document the hi3559a clock bindings
clk: si5341: Add sysfs properties to allow checking/resetting device faults
clk: si5341: Add silabs,iovdd-33 property
clk: si5341: Add silabs,xaxb-ext-clk property
clk: si5341: Allow different output VDD_SEL values
clk: si5341: Update initialization magic
clk: si5341: Check for input clock presence and PLL lock on startup
...
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The device is not losing context on CPU_CLUSTER_PM_ERROR. As we are only
saving and restoring context with cpu_pm, there is no need to restore the
context in case of an error.
Note that the unnecessary restoring of context does not cause issues, it's
just not needed.
Cc: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210518075306.35532-1-tony@atomide.com
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Bad counter reads are experienced sometimes when bit 10 or greater rolls
over. Originally, testing showed that at least 10 lower bits would be
set to the same value during these bad reads. However, some users still
reported time skips.
Wider testing revealed that on some chips, occasionally only the lowest
9 bits would read as the anomalous value. During these reads (which
still happen only when bit 10), bit 9 would read as the correct value.
Reduce the mask by one bit to cover these cases as well.
Cc: stable@vger.kernel.org
Fixes: c950ca8c35ee ("clocksource/drivers/arch_timer: Workaround for Allwinner A64 timer instability")
Reported-by: Roman Stratiienko <r.stratiienko@gmail.com>
Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210515021439.55316-1-samuel@sholland.org
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arm_global_timer
Fix the following coccicheck warning:
drivers/clocksource/arm_global_timer.c:107:4-23:
duplicated argument to & or |
Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210615115440.8881-1-wanjiabing@vivo.com
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The sparse tool complains as follows:
drivers/clocksource/arm_global_timer.c:54:23: warning:
symbol 'gt_clk_rate_change_nb' was not declared. Should it be static?
This symbol is not used outside of arm_global_timer.c, so mark it static.
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zou Wei <zou_wei@huawei.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/1623490046-37972-1-git-send-email-zou_wei@huawei.com
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Now ARM global timer driver could work even if it's source clock rate
changes, so we don't need to disable that driver when cpu frequency scaling
is in use.
This cause Zynq arch to get support for timer delay and get_cycles().
Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
Cc: Patrice Chotard <patrice.chotard@st.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: Sören Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210406130045.15491-3-andrea.merello@gmail.com
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source clock changes
This patch adds rate change notification support for the parent clock;
should that clock change, then we try to adjust the our prescaler in order
to compensate (i.e. we adjust to still get the same timer frequency).
This is loosely based on what it's done in timer-cadence-ttc. timer-sun51,
mips-gic-timer and smp_twd.c also seem to look at their parent clock rate
and to perform some kind of adjustment whenever needed.
In this particular case we have only one single counter and prescaler for
all clocksource, clockevent and timer_delay, and we just update it for all
(i.e. we don't let it go and call clockevents_update_freq() to notify to
the kernel that our rate has changed).
Note that, there is apparently no other way to fixup things, because once
we call register_current_timer_delay(), specifying the timer rate, it seems
that that rate is not supposed to change ever.
In order for this mechanism to work, we have to make assumptions about how
much the initial clock is supposed to eventually decrease from the initial
one, and set our initial prescaler to a value that we can eventually
decrease enough to compensate. We provide an option in KConfig for this.
In case we end up in a situation in which we are not able to compensate the
parent clock change, we fail returning NOTIFY_BAD.
This fixes a real-world problem with Zynq arch not being able to use this
driver and CPU_FREQ at the same time (because ARM global timer is fed by
the CPU clock, which may keep changing when CPU_FREQ is enabled).
Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
Cc: Patrice Chotard <patrice.chotard@st.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: Sören Brinkmann <soren.brinkmann@xilinx.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210406130045.15491-2-andrea.merello@gmail.com
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