Naohiko Shimizu eaa9bb1d39 riscv: clocksource: Fix stimecmp update hazard on RV32 ... On RV32, updating the 64-bit stimecmp (or vstimecmp) CSR requires two separate 32-bit writes. A race condition exists if the timer triggers during these two writes. The RISC-V Privileged Specification (e.g., Section 3.2.1 for mtimecmp) recommends a specific 3-step sequence to avoid spurious interrupts when updating 64-bit comparison registers on 32-bit systems: 1. Set the low-order bits (stimecmp) to all ones (ULONG_MAX). 2. Set the high-order bits (stimecmph) to the desired value. 3. Set the low-order bits (stimecmp) to the desired value. Current implementation writes the LSB first without ensuring a future value, which may lead to a transient state where the 64-bit comparison is incorrectly evaluated as "expired" by the hardware. This results in spurious timer interrupts. This patch adopts the spec-recommended 3-step sequence to ensure the intermediate 64-bit state is never smaller than the current time. Fixes: 9f7a8ff639 ("RISC-V: Prefer sstc extension if available") Signed-off-by: Naohiko Shimizu <naohiko.shimizu@gmail.com> Reviewed-by: Anup Patel <anup@brainfault.org> Link: https://patch.msgid.link/20260104135938.524-2-naohiko.shimizu@gmail.com Signed-off-by: Paul Walmsley <pjw@kernel.org>		2026-01-14 17:42:46 -07:00
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Kconfig	clocksource/drivers: Add Realtek system timer driver	2025-11-26 11:25:15 +01:00
Makefile	clocksource/drivers: Add Realtek system timer driver	2025-11-26 11:25:15 +01:00
acpi_pm.c	clocksource: acpi_pm: Add external callback for suspend/resume	2024-09-06 14:49:20 +02:00
arc_timer.c	…
arm_arch_timer.c	clocksource/drivers/arm_arch_timer_mmio: Switch over to standalone driver	2025-09-23 12:31:50 +02:00
arm_arch_timer_mmio.c	clocksource/drivers/arm_arch_timer_mmio: Prevent driver unbind	2025-11-26 11:24:47 +01:00
arm_global_timer.c	clocksource/drivers/arm_global_timer: Add auto-detection for initial prescaler values	2025-09-23 12:41:58 +02:00
armv7m_systick.c	…
asm9260_timer.c	clocksource/drivers/asm9260: Add missing clk_disable_unprepare in asm9260_timer_init	2024-09-06 14:49:21 +02:00
bcm2835_timer.c	…
bcm_kona_timer.c	…
clksrc-dbx500-prcmu.c	…
clksrc_st_lpc.c	…
clps711x-timer.c	clocksource/drivers/clps711x: Fix resource leaks in error paths	2025-09-23 12:42:27 +02:00
dummy_timer.c	…
dw_apb_timer.c	clocksource/drivers/dw_apb: Remove unused dw_apb_clockevent functions	2024-11-13 13:49:33 +01:00
dw_apb_timer_of.c	…
em_sti.c	…
exynos_mct.c	clocksource/drivers/exynos_mct: Fixed a spelling error	2025-03-07 17:55:59 +01:00
hyperv_timer.c	clocksource: hyper-v: Skip unnecessary checks for the root partition	2025-09-08 22:10:46 +00:00
i8253.c	clocksource/i8253: Use raw_spinlock_irqsave() in clockevent_i8253_disable()	2025-05-05 15:34:49 +02:00
ingenic-ost.c	clocksource/drivers/ingenic: Use devm_clk_get_enabled() helpers	2024-09-06 14:49:20 +02:00
ingenic-sysost.c	clocksource/drivers/ingenic-sysost: Convert from round_rate() to determine_rate()	2025-09-23 12:41:50 +02:00
ingenic-timer.c	…
jcore-pit.c	irqchip/jcore-aic, clocksource/drivers/jcore: Fix jcore-pit interrupt request	2025-02-17 23:27:49 +01:00
mips-gic-timer.c	clocksource: mips-gic-timer: Enable counter when CPUs start	2025-02-21 10:19:14 +01:00
mmio.c	…
mps2-timer.c	…
mxs_timer.c	…
nomadik-mtu.c	…
numachip.c	…
renesas-ostm.c	clocksource/drivers/renesas-ostm: Unconditionally enable reprobe support	2025-05-16 13:33:11 +02:00
samsung_pwm_timer.c	of: remove internal arguments from of_property_for_each_u32()	2024-07-25 06:53:47 -05:00
scx200_hrt.c	clocksource/drivers/scx200: Add module owner	2025-09-23 10:21:24 +02:00
sh_cmt.c	clocksource/drivers/sh_cmt: Always leave device running after probe	2025-11-26 11:24:40 +01:00
sh_mtu2.c	…
sh_tmu.c	…
timer-armada-370-xp.c	syscore: Pass context data to callbacks	2025-11-14 10:01:52 +01:00
timer-atmel-pit.c	…
timer-atmel-st.c	…
timer-atmel-tcb.c	…
timer-cadence-ttc.c	clocksource/drivers/cadence-ttc: Add missing clk_disable_unprepare in ttc_setup_clockevent	2024-09-06 14:49:21 +02:00
timer-clint.c	riscv: Use IPIs for remote cache/TLB flushes by default	2024-04-29 10:49:26 -07:00
timer-cs5535.c	clocksource/drivers/cs5535: Add module owner	2025-09-23 10:52:23 +02:00
timer-davinci.c	…
timer-digicolor.c	…
timer-econet-en751221.c	clocksource/timer-econet-en751221: Convert comma to semicolon	2025-09-23 10:56:13 +02:00
timer-ep93xx.c	…
timer-fsl-ftm.c	…
timer-fttmr010.c	…
timer-goldfish.c	…
timer-gx6605s.c	…
timer-gxp.c	clocksource/drivers/gpx: Remove redundant casts	2024-11-13 13:49:33 +01:00
timer-imx-gpt.c	…
timer-imx-sysctr.c	…
timer-imx-tpm.c	clocksource/drivers/imx-tpm: Fix next event not taking effect sometime	2024-09-02 10:04:15 +02:00
timer-integrator-ap.c	…
timer-ixp4xx.c	…
timer-keystone.c	…
timer-loongson1-pwm.c	…
timer-lpc32xx.c	…
timer-mediatek-cpux.c	…
timer-mediatek.c	…
timer-meson6.c	…
timer-microchip-pit64b.c	…
timer-milbeaut.c	…
timer-mp-csky.c	…
timer-msc313e.c	…
timer-npcm7xx.c	…
timer-nxp-pit.c	clocksource/drivers/nxp-pit: Prevent driver unbind	2025-11-26 11:24:57 +01:00
timer-nxp-stm.c	clocksource/drivers/nxp-stm: Prevent driver unbind	2025-11-26 11:25:03 +01:00
timer-of.c	clocksource/drivers/timer-of: Remove percpu irq related code	2024-09-02 10:04:15 +02:00
timer-of.h	clocksource/drivers/timer-of: Remove percpu irq related code	2024-09-02 10:04:15 +02:00
timer-orion.c	arm: Handle KCOV __init vs inline mismatches	2025-07-21 21:43:39 -07:00
timer-owl.c	…
timer-pistachio.c	…
timer-probe.c	…
timer-pxa.c	…
timer-qcom.c	clocksource/drivers/qcom: Remove clockevents shutdown call on offlining	2024-10-31 10:41:43 +01:00
timer-ralink.c	clocksource/drivers/ralink: Fix resource leaks in init error path	2025-11-26 11:24:34 +01:00
timer-rda.c	clocksource/drivers/rda: Add sched_clock_register for RDA8810PL SoC	2025-11-26 11:25:11 +01:00
timer-realtek.c	clocksource/drivers: Add Realtek system timer driver	2025-11-26 11:25:15 +01:00
timer-riscv.c	riscv: clocksource: Fix stimecmp update hazard on RV32	2026-01-14 17:42:46 -07:00
timer-rockchip.c	…
timer-rtl-otto.c	clocksource/drivers/timer-rtl-otto: Simplify documentation	2025-09-23 12:41:26 +02:00
timer-sp.h	…
timer-sp804.c	clocksource/drivers/timer-sp804: Fix read_current_timer() issue when clock source is not registered	2025-11-26 11:24:32 +01:00
timer-sprd.c	clocksource/drivers/sprd: Enable register for timer counter from 32 bit to 64 bit	2025-11-26 11:24:26 +01:00
timer-stm32-lp.c	clocksource/drivers/stm32-lp: Drop unused module alias	2025-11-26 11:25:15 +01:00
timer-stm32.c	…
timer-sun4i.c	…
timer-sun5i.c	clocksource/drivers/sun5i: Add module owner	2025-09-23 10:51:44 +02:00
timer-tegra.c	clocksource/drivers/timer-tegra: Remove clockevents shutdown call on offlining	2024-10-31 10:41:43 +01:00
timer-tegra186.c	clocksource/drivers/timer-tegra186: Don't print superfluous errors	2025-09-23 12:41:39 +02:00
timer-ti-32k.c	…
timer-ti-dm-systimer.c	clocksource/drivers/arm_arch_timer: Use of_property_present() for non-boolean properties	2024-11-13 13:49:33 +01:00
timer-ti-dm.c	clocksource/drivers/timer-ti-dm : Capture functionality for OMAP DM timer	2025-09-23 12:32:40 +02:00
timer-versatile.c	…
timer-vt8500.c	…
timer-zevio.c	…