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171b45a4a7
linux-next/drivers/clocksource
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Andrea Merello 171b45a4a7 clocksource/drivers/arm_global_timer: Implement rate compensation whenever 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
2021-06-16 17:33:04 +02:00
..
acpi_pm.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 243 2019-06-19 17:09:07 +02:00
arc_timer.c clocksource/drivers/arc_timer: Remove duplicate error message 2020-05-22 23:58:56 +02:00
arm_arch_timer.c clocksource/drivers/arm_arch_timer: Remove arch_timer_rate1 2021-06-03 22:15:12 +02:00
arm_global_timer.c clocksource/drivers/arm_global_timer: Implement rate compensation whenever source clock changes 2021-06-16 17:33:04 +02:00
armv7m_systick.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 194 2019-05-30 11:29:22 -07:00
asm9260_timer.c clocksource/drivers/asm9260: Add a check for of_clk_get 2019-11-04 10:40:10 +01:00
bcm2835_timer.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
bcm_kona_timer.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
clksrc_st_lpc.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
clksrc-dbx500-prcmu.c timekeeping, clocksource: Fix various typos in comments 2021-03-22 23:06:48 +01:00
clps711x-timer.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
dummy_timer.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
dw_apb_timer_of.c clocksource/drivers/dw_apb_timer_of: Add handling for potential memory leak 2021-04-08 13:24:53 +02:00
dw_apb_timer.c clocksource: dw_apb_timer: Make CPU-affiliation being optional 2020-05-23 00:02:41 +02:00
em_sti.c clocksource/drivers/em_sti: Fix variable declaration in em_sti_probe 2020-01-16 19:06:57 +01:00
exynos_mct.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
h8300_timer8.c clocksource/drivers/h8300_timer8: Fix wrong return value in h8300_8timer_init() 2020-08-24 13:01:38 +02:00
h8300_timer16.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
h8300_tpu.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
hyperv_timer.c clocksource/drivers/hyper-v: Re-enable VDSO_CLOCKMODE_HVCLOCK on X86 2021-05-14 14:55:13 +02:00
i8253.c clockevents/drivers/i8253: Add support for PIT shutdown quirk 2018-11-04 11:04:46 +01:00
ingenic-ost.c clocksource/drivers/ingenic_ost: Fix return value check in ingenic_ost_probe() 2021-04-08 13:24:15 +02:00
ingenic-sysost.c clocksource/drivers/ingenic: Rename unreasonable array names 2021-06-15 14:14:14 +02:00
ingenic-timer.c clocksource/drivers/ingenic: Add support for the JZ4760 2021-04-08 13:23:22 +02:00
jcore-pit.c clocksource/drivers: Rename CLOCKSOURCE_OF_DECLARE to TIMER_OF_DECLARE 2017-06-14 11:58:45 +02:00
Kconfig clocksource/drivers/arm_global_timer: Implement rate compensation whenever source clock changes 2021-06-16 17:33:04 +02:00
Makefile clocksource/drivers/prima: Remove sirf prima driver 2021-02-03 09:13:46 +01:00
mips-gic-timer.c clocksource: mips-gic-timer: Mark GIC timer as unstable if ref clock changes 2020-05-23 00:03:16 +02:00
mmio.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
mps2-timer.c clocksource/drivers/mps2-timer: Use semicolons rather than commas to separate statements 2020-10-01 10:07:26 +02:00
mxs_timer.c clocksource/drivers/mxs_timer: Add missing semicolon when DEBUG is defined 2021-01-18 22:28:59 +01:00
nomadik-mtu.c clocksource/drivers/nomadik-mtu: Handle 32kHz clock 2020-07-23 16:57:43 +02:00
numachip.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 282 2019-06-05 17:36:37 +02:00
renesas-ostm.c clocksource/drivers/renesas-ostm: Use unique device name instead of ostm 2019-11-04 10:38:46 +01:00
samsung_pwm_timer.c clocksource/drivers/samsung_pwm: Constify source IO memory 2021-06-04 10:12:13 +02:00
scx200_hrt.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
sh_cmt.c clocksource/drivers/sh_cmt: Don't use CMTOUT_IE with R-Car Gen2/3 2021-04-08 13:24:16 +02:00
sh_mtu2.c PM: domains: Rename pm_genpd_syscore_poweroff|poweron() 2020-11-10 20:42:01 +01:00
sh_tmu.c PM: domains: Rename pm_genpd_syscore_poweroff|poweron() 2020-11-10 20:42:01 +01:00
timer-armada-370-xp.c clocksource/drivers/armada-370-xp: Use semicolons rather than commas to separate statements 2020-10-02 16:27:28 +02:00
timer-atcpit100.c clocksource/drivers: Set clockevent device cpumask to cpu_possible_mask 2018-07-26 11:26:30 +02:00
timer-atmel-pit.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
timer-atmel-st.c clocksource/drivers/atmel-st: Remove useless 'status' 2020-04-15 10:57:15 +02:00
timer-atmel-tcb.c timekeeping, clocksource: Fix various typos in comments 2021-03-22 23:06:48 +01:00
timer-cadence-ttc.c clocksource/drivers/cadence_ttc: Fix memory leak in ttc_setup_clockevent() 2020-12-03 19:16:26 +01:00
timer-clint.c clocksource: clint: Export clint_time_val for modules 2020-09-29 23:55:27 -07:00
timer-cs5535.c clocksource/drivers/timer-cs5535: Request irq with non-NULL dev_id 2020-03-12 19:23:06 +01:00
timer-davinci.c clocksource/drivers/davinci: Move pr_fmt() before the includes 2021-01-18 16:31:39 +01:00
timer-digicolor.c clocksource/drivers: Rename CLOCKSOURCE_OF_DECLARE to TIMER_OF_DECLARE 2017-06-14 11:58:45 +02:00
timer-fsl-ftm.c timekeeping, clocksource: Fix various typos in comments 2021-03-22 23:06:48 +01:00
timer-fttmr010.c clocksource/drivers/fttmr010: Set interrupt and shutdown 2020-02-21 09:28:38 +01:00
timer-gx6605s.c clocksource/drivers/timer-gx6605s: Fixup counter reload 2020-08-24 13:01:39 +02:00
timer-imx-gpt.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
timer-imx-sysctr.c clocksource/drivers/imx-sysctr: Remove unused includes 2020-03-17 10:11:45 +01:00
timer-imx-tpm.c clocksource/drivers/imx-tpm: Add support for ARM64 2020-04-09 16:24:50 +02:00
timer-integrator-ap.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
timer-ixp4xx.c clocksource/drivers/ixp4xx: Implement delay timer 2019-06-25 19:49:18 +02:00
timer-keystone.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
timer-lpc32xx.c clocksource/drivers: Unify the names to timer-* format 2018-10-03 14:37:02 +02:00
timer-mediatek.c clocksource/drivers/mediatek: Ack and disable interrupts on suspend 2021-06-15 14:14:03 +02:00
timer-meson6.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
timer-microchip-pit64b.c timekeeping, clocksource: Fix various typos in comments 2021-03-22 23:06:48 +01:00
timer-milbeaut.c clocksource/drivers/timer-milbeaut: Cleanup common register accesses 2019-05-02 21:55:58 +02:00
timer-mp-csky.c clocksource/drivers/c-sky: fixup ftrace call-graph panic 2018-12-31 23:17:23 +08:00
timer-npcm7xx.c clocksource/drivers/npcm: Add support for WPCM450 2021-04-08 13:24:16 +02:00
timer-of.c timekeeping, clocksource: Fix various typos in comments 2021-03-22 23:06:48 +01:00
timer-of.h clocksource/drivers/timer-of: Store the device node pointer in 'struct timer_of' 2018-01-08 17:57:24 +01:00
timer-orion.c clocksource/drivers/orion: Add missing clk_disable_unprepare() on error path 2020-12-03 19:16:26 +01:00
timer-owl.c clocksource/drivers/owl: Improve owl_timer_init fail messages 2020-02-27 09:42:00 +01:00
timer-oxnas-rps.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 201 2019-05-30 11:29:52 -07:00
timer-pistachio.c clocksource/drivers/pistachio: Fix trivial typo 2021-04-08 13:24:15 +02:00
timer-probe.c treewide: Convert macro and uses of __section(foo) to __section("foo") 2020-10-25 14:51:49 -07:00
timer-pxa.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
timer-qcom.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 282 2019-06-05 17:36:37 +02:00
timer-rda.c clocksource/drivers/rda: Add clock driver for RDA8810PL SoC 2018-12-18 22:22:23 +01:00
timer-riscv.c RISC-V: Remove CLINT related code from timer and arch 2020-08-20 10:58:13 -07:00
timer-rockchip.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
timer-sp804.c clocksource/drivers/sp804: Use pr_fmt 2020-12-03 19:16:18 +01:00
timer-sp.h clocksource/drivers/sp804: Enable Hisilicon sp804 timer 64bit mode 2020-09-24 10:51:04 +02:00
timer-sprd.c clocksource/drivers/sprd: Register one always-on timer to compensate suspend time 2018-07-26 11:26:34 +02:00
timer-stm32-lp.c clocksource: Add Low Power STM32 timers driver 2020-06-18 11:19:58 +01:00
timer-stm32.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 194 2019-05-30 11:29:22 -07:00
timer-sun4i.c clocksource: sun4i: Add missing compatibles 2019-08-27 00:31:39 +02:00
timer-sun5i.c clocksource/drivers/sun5i: Fail gracefully when clock rate is unavailable 2019-02-23 12:13:45 +01:00
timer-tegra.c clocksource/drivers/tegra: Set up maximum-ticks limit properly 2019-06-25 19:49:18 +02:00
timer-ti-32k.c clocksource/drivers: Replace HTTP links with HTTPS ones 2020-07-23 16:57:43 +02:00
timer-ti-dm-systimer.c clocksource/drivers/timer-ti-dm: Handle dra7 timer wrap errata i940 2021-04-08 16:41:18 +02:00
timer-ti-dm.c clocksource/drivers/timer-ti-dm: Save and restore timer TIOCP_CFG 2021-06-15 14:14:14 +02:00
timer-versatile.c clocksource/drivers/timer-versatile: Clear OF_POPULATED flag 2020-05-23 00:03:25 +02:00
timer-vf-pit.c timekeeping, clocksource: Fix various typos in comments 2021-03-22 23:06:48 +01:00
timer-vt8500.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
timer-zevio.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00