linux.git/drivers/clocksource, branch v6.0.14

Revert "clocksource/drivers/riscv: Events are stopped during CPU suspend"

2022-12-08T10:30:22+00:00

[ Upstream commit d9f15a9de44affe733e34f93bc184945ba277e6d ]

This reverts commit 232ccac1bd9b5bfe73895f527c08623e7fa0752d.

On the subject of suspend, the RISC-V SBI spec states:

  This does not cover whether any given events actually reach the hart or
  not, just what the hart will do if it receives an event. On PolarFire
  SoC, and potentially other SiFive based implementations, events from the
  RISC-V timer do reach a hart during suspend. This is not the case for the
  implementation on the Allwinner D1 - there timer events are not received
  during suspend.

To fix this, the CLOCK_EVT_FEAT_C3STOP (mis)feature was enabled for the
timer driver - but this has broken both RCU stall detection and timers
generally on PolarFire SoC and potentially other SiFive based
implementations.

If an AXI read to the PCIe controller on PolarFire SoC times out, the
system will stall, however, with CLOCK_EVT_FEAT_C3STOP active, the system
just locks up without RCU stalling:

	io scheduler mq-deadline registered
	io scheduler kyber registered
	microchip-pcie 2000000000.pcie: host bridge /soc/pcie@2000000000 ranges:
	microchip-pcie 2000000000.pcie:      MEM 0x2008000000..0x2087ffffff -> 0x0008000000
	microchip-pcie 2000000000.pcie: sec error in pcie2axi buffer
	microchip-pcie 2000000000.pcie: ded error in pcie2axi buffer
	microchip-pcie 2000000000.pcie: axi read request error
	microchip-pcie 2000000000.pcie: axi read timeout
	microchip-pcie 2000000000.pcie: sec error in pcie2axi buffer
	microchip-pcie 2000000000.pcie: ded error in pcie2axi buffer
	microchip-pcie 2000000000.pcie: sec error in pcie2axi buffer
	microchip-pcie 2000000000.pcie: ded error in pcie2axi buffer
	microchip-pcie 2000000000.pcie: sec error in pcie2axi buffer
	microchip-pcie 2000000000.pcie: ded error in pcie2axi buffer
	Freeing initrd memory: 7332K

Similarly issues were reported with clock_nanosleep() - with a test app
that sleeps each cpu for 6, 5, 4, 3 ms respectively, HZ=250 & the blamed
commit in place, the sleep times are rounded up to the next jiffy:

== CPU: 1 ==      == CPU: 2 ==      == CPU: 3 ==      == CPU: 4 ==
Mean: 7.974992    Mean: 7.976534    Mean: 7.962591    Mean: 3.952179
Std Dev: 0.154374 Std Dev: 0.156082 Std Dev: 0.171018 Std Dev: 0.076193
Hi: 9.472000      Hi: 10.495000     Hi: 8.864000      Hi: 4.736000
Lo: 6.087000      Lo: 6.380000      Lo: 4.872000      Lo: 3.403000
Samples: 521      Samples: 521      Samples: 521      Samples: 521

Fortunately, the D1 has a second timer, which is "currently used in
preference to the RISC-V/SBI timer driver" so a revert here does not
hurt operation of D1 in its current form.

Ultimately, a DeviceTree property (or node) will be added to encode the
behaviour of the timers, but until then revert the addition of
CLOCK_EVT_FEAT_C3STOP.

Fixes: 232ccac1bd9b ("clocksource/drivers/riscv: Events are stopped during CPU suspend")
Signed-off-by: Conor Dooley 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Palmer Dabbelt 
Acked-by: Palmer Dabbelt 
Acked-by: Samuel Holland 
Link: https://lore.kernel.org/linux-riscv/YzYTNQRxLr7Q9JR0@spud/
Link: https://github.com/riscv-non-isa/riscv-sbi-doc/issues/98/
Link: https://lore.kernel.org/linux-riscv/bf6d3b1f-f703-4a25-833e-972a44a04114@sholland.org/
Link: https://lore.kernel.org/r/20221122121620.3522431-1-conor.dooley@microchip.com
Signed-off-by: Sasha Levin

clocksource/drivers/arm_arch_timer: Fix XGene-1 TVAL register math error

2022-12-08T10:30:15+00:00

[ Upstream commit 839a973988a94c15002cbd81536e4af6ced2bd30 ]

The TVAL register is 32 bit signed. Thus only the lower 31 bits are
available to specify when an interrupt is to occur at some time in the
near future. Attempting to specify a larger interval with TVAL results
in a negative time delta which means the timer fires immediately upon
being programmed, rather than firing at that expected future time.

The solution is for Linux to declare that TVAL is a 31 bit register rather
than give its true size of 32 bits. This prevents Linux from programming
TVAL with a too-large value. Note that, prior to 5.16, this little trick
was the standard way to handle TVAL in Linux, so there is nothing new
happening here on that front.

The softlockup detector hides the issue, because it keeps generating
short timer deadlines that are within the scope of the broken timer.

Disabling it, it starts using NO_HZ with much longer timer deadlines, which
turns into an interrupt flood:

11: 1124855130 949168462 758009394 76417474 104782230 30210281
310890 1734323687 GICv2 29 Level arch_timer

And "much longer" isn't that long: it takes less than 43s to underflow
TVAL at 50MHz (the frequency of the counter on XGene-1).

Some comments on the v1 version of this patch by Marc Zyngier:

XGene implements CVAL (a 64bit comparator) in terms of TVAL (a countdown
register) instead of the other way around. TVAL being a 32bit register,
the width of the counter should equally be 32. However, TVAL is a
*signed* value, and keeps counting down in the negative range once the
timer fires.

It means that any TVAL value with bit 31 set will fire immediately,
as it cannot be distinguished from an already expired timer. Reducing
the timer range back to a paltry 31 bits papers over the issue.

Another problem cannot be fixed though, which is that the timer interrupt
*must* be handled within the negative countdown period, or the interrupt
will be lost (TVAL will rollover to a positive value, indicative of a
new timer deadline).

Fixes: 012f18850452 ("clocksource/drivers/arm_arch_timer: Work around broken CVAL implementations")
Signed-off-by: Joe Korty
Signed-off-by: Marc Zyngier
Signed-off-by: Thomas Gleixner
Reviewed-by: Marc Zyngier
Link: https://lore.kernel.org/r/20221024165422.GA51107@zipoli.concurrent-rt.com
Link: https://lore.kernel.org/r/20221121145343.896018-1-maz@kernel.org

[maz: revamped the commit message]

Signed-off-by: Sasha Levin

clocksource/drivers/timer-gxp: Add missing error handling in gxp_timer_probe

2022-10-21T10:39:00+00:00

[ Upstream commit 0e2c8e6d769bcdc4f6634a02c545356282275e68 ]

Add platform_device_put() to make sure to free the platform
device in the event platform_device_add() fails.

Fixes: 5184f4bf151b ("clocksource/drivers/timer-gxp: Add HPE GXP Timer")
Signed-off-by: Lin Yujun 
Link: https://lore.kernel.org/r/20220914033018.97484-1-linyujun809@huawei.com
Signed-off-by: Daniel Lezcano 
Signed-off-by: Sasha Levin

clocksource/drivers/arm_arch_timer: Fix handling of ARM erratum 858921

2022-10-21T10:38:59+00:00

[ Upstream commit 6c3b62d93e195f78c1437c8fa7581e9b2f00886e ]

The commit a38b71b0833e ("clocksource/drivers/arm_arch_timer:
Move system register timer programming over to CVAL") moves the
programming of the timers from the countdown timer (TVAL) over
to the comparator (CVAL). This makes it necessary to read the
counter when programming next event. However, the workaround of
Cortex-A73 erratum 858921 does not set the corresponding
set_next_event_phys and set_next_event_virt.

Add the appropriate hooks to apply the erratum mitigation when
programming the next timer event.

Fixes: a38b71b0833e ("clocksource/drivers/arm_arch_timer: Move system register timer programming over to CVAL")
Signed-off-by: Kunkun Jiang 
Acked-by: Marc Zyngier 
Reviewed-by: Oliver Upton 
Link: https://lore.kernel.org/r/20220914061424.1260-1-jiangkunkun@huawei.com
Signed-off-by: Daniel Lezcano 
Signed-off-by: Sasha Levin

clocksource/drivers/arm_arch_timer: Fix CNTPCT_LO and CNTVCT_LO value

2022-10-21T10:37:42+00:00

commit af246cc6d0ed11318223606128bb0b09866c4c08 upstream.

CNTPCT_LO and CNTVCT_LO are defined by mistake in commit '8b82c4f883a7',
so fix them according to the Arm ARM DDI 0487I.a, Table I2-4
"CNTBaseN memory map" as follows:

Offset    Register      Type Description
0x000     CNTPCT[31:0]  RO   Physical Count register.
0x004     CNTPCT[63:32] RO
0x008     CNTVCT[31:0]  RO   Virtual Count register.
0x00C     CNTVCT[63:32] RO

Fixes: 8b82c4f883a7 ("clocksource/drivers/arm_arch_timer: Move MMIO timer programming over to CVAL")
Cc: stable@vger.kernel.org
Cc: Daniel Lezcano 
Cc: Thomas Gleixner 
Cc: Marc Zyngier 
Cc: Mark Rutland 
Acked-by: Marc Zyngier 
Signed-off-by: Yang Guo 
Signed-off-by: Shaokun Zhang 
Link: https://lore.kernel.org/r/20220927033221.49589-1-zhangshaokun@hisilicon.com
Signed-off-by: Daniel Lezcano 
Signed-off-by: Greg Kroah-Hartman

RISC-V: Add Sstc extension support

2022-08-11T21:41:52+00:00

This series implements Sstc extension support which was ratified
recently.  Before the Sstc extension, an SBI call is necessary to
generate timer interrupts as only M-mode have access to the timecompare
registers. Thus, there is significant latency to generate timer
interrupts at kernel.  For virtualized enviornments, its even worse as
the KVM handles the SBI call and uses a software timer to emulate the
timecomapre register.

Sstc extension solves both these problems by defining a
stimecmp/vstimecmp at supervisor (host/guest) level. It allows kernel to
program a timer and recieve interrupt without supervisor execution
enviornment (M-mode/HS mode) intervention.

* palmer/riscv-sstc:
  RISC-V: Prefer sstc extension if available
  RISC-V: Enable sstc extension parsing from DT
  RISC-V: Add SSTC extension CSR details

RISC-V: Prefer sstc extension if available

2022-08-11T21:36:55+00:00

RISC-V ISA has sstc extension which allows updating the next clock event
via a CSR (stimecmp) instead of an SBI call. This should happen dynamically
if sstc extension is available. Otherwise, it will fallback to SBI call
to maintain backward compatibility.

Reviewed-by: Anup Patel 
Signed-off-by: Atish Patra 
Reviewed-by: Guo Ren 
Link: https://lore.kernel.org/r/20220722165047.519994-4-atishp@rivosinc.com
Signed-off-by: Palmer Dabbelt

Merge tag 'riscv-for-linus-5.20-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

2022-08-06T22:04:48+00:00

Pull RISC-V updates from Palmer Dabbelt:

 - Enabling the FPU is now a static_key

 - Improvements to the Svpbmt support

 - CPU topology bindings for a handful of systems

 - Support for systems with 64-bit hart IDs

 - Many settings have been enabled in the defconfig, including both
   support for the StarFive systems and many of the Docker requirements

There are also a handful of cleanups and improvements, as usual.

* tag 'riscv-for-linus-5.20-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (28 commits)
  riscv: enable Docker requirements in defconfig
  riscv: convert the t-head pbmt errata to use the __nops macro
  riscv: introduce nops and __nops macros for NOP sequences
  RISC-V: Add fast call path of crash_kexec()
  riscv: mmap with PROT_WRITE but no PROT_READ is invalid
  riscv/efi_stub: Add 64bit boot-hartid support on RV64
  riscv: cpu: Add 64bit hartid support on RV64
  riscv: smp: Add 64bit hartid support on RV64
  riscv: spinwait: Fix hartid variable type
  riscv: cpu_ops_sbi: Add 64bit hartid support on RV64
  riscv: dts: sifive: "fix" pmic watchdog node name
  riscv: dts: canaan: Add k210 topology information
  riscv: dts: sifive: Add fu740 topology information
  riscv: dts: sifive: Add fu540 topology information
  riscv: dts: starfive: Add JH7100 CPU topology
  RISC-V: Add CONFIG_{NON,}PORTABLE
  riscv: config: enable SOC_STARFIVE in defconfig
  riscv: dts: microchip: Add mpfs' topology information
  riscv: Kconfig.socs: Add comments
  riscv: Kconfig.erratas: Add comments
  ...

Merge tag 'timers-v5.20-rc1' of https://git.linaro.org/people/daniel.lezcano/linux into timers/core

2022-07-28T10:33:34+00:00

Pull clockevent/source updates from Daniel Lezcano:

  - Add the missing DT bindings for the MTU nomadik timer (Linus
    Walleij)

  - Fix grammar typo in the ARM global timer Kconfig option (Randy
    Dunlap)

  - Add the tegra186 timer and use it on the tegra234 board (Thierry
    Reding)

  - Add the 'CPUXGPT' CPU timer for Mediatek MT6795 and implement a
    workaround to overcome an ATF bug where the timer is not correctly
    initialized (AngeloGioacchino Del Regno)

  - Rework the suspend/resume approach to enable the feature on the
    timer even it is not an active clock and fix a compilation warning
    (Claudiu Beznea)

  - Add the Add R-Car Gen4 timer support along with the DT bindings
    (Wolfram Sang)

  - Add compatible for ti,am654-timer to support AM6 SoC (Tony Lindgren)

  - Fix Kconfig option to put it back to 'bool' instead of 'tristate'
    for the tegra186 (Daniel Lezcano)

  - Sort 'family,type' DT bindings for the Renesas timers (Geert
    Uytterhoeven)

  - Add compatible 'allwinner,sun20i-d1-timer' for Allwinner D1 (Samuel
    Holland)

  - Remove unnecessary (void*) conversions for sun4i (XU pengfei)

  - Remove unnecessary (void*) conversions for sun5i (Li zeming)

Link: https://lore.kernel.org/all/7472984e-f502-5f27-82bf-070127dd85a5@linaro.org

clocksource/drivers/sun5i: Remove unnecessary (void*) conversions

2022-07-27T15:01:52+00:00

Remove unnecessary void* type castings.

Signed-off-by: Li zeming 
Link: https://lore.kernel.org/r/20220727083751.5540-1-zeming@nfschina.com
Signed-off-by: Daniel Lezcano