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  1. 21 8月, 2020 1 次提交
  3. 23 7月, 2020 2 次提交
  5. 18 6月, 2020 1 次提交
  7. 23 5月, 2020 2 次提交
  9. 27 4月, 2020 2 次提交
  11. 27 2月, 2020 1 次提交
  13. 17 1月, 2020 3 次提交
  15. 04 11月, 2019 1 次提交
  17. 27 8月, 2019 1 次提交
  19. 09 8月, 2019 1 次提交
    • P
      clocksource: Add a new timer-ingenic driver · 34e93683
      由 Paul Cercueil 提交于 
      This driver handles the TCU (Timer Counter Unit) present on the Ingenic
JZ47xx SoCs, and provides the kernel with a system timer, a clocksource
and a sched_clock.
Signed-off-by: NPaul Cercueil <paul@crapouillou.net>
Tested-by: NMathieu Malaterre <malat@debian.org>
Tested-by: NArtur Rojek <contact@artur-rojek.eu>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NPaul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-mips@vger.kernel.org
Cc: linux-clk@vger.kernel.org
Cc: od@zcrc.me
      34e93683
  21. 26 6月, 2019 3 次提交
  23. 21 5月, 2019 1 次提交
  25. 03 5月, 2019 3 次提交
  27. 23 4月, 2019 1 次提交
  29. 12 4月, 2019 1 次提交
  31. 01 3月, 2019 1 次提交
  33. 23 2月, 2019 2 次提交
    • J
      clocksource/drivers/tegra: Add Tegra210 timer support · b4822dc7
      由 Joseph Lo 提交于 
      Add support for the Tegra210 timer that runs at oscillator clock
(TMR10-TMR13). We need these timers to work as clock event device and to
replace the ARMv8 architected timer due to it can't survive across the
power cycle of the CPU core or CPUPORESET signal. So it can't be a wake-up
source when CPU suspends in power down state.

Also convert the original driver to use timer-of API.

Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NJoseph Lo <josephl@nvidia.com>
Acked-by: NThierry Reding <treding@nvidia.com>
Acked-by: NJon Hunter <jonathanh@nvidia.com>
Acked-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
      b4822dc7
    • S
      clocksource/drivers/arch_timer: Workaround for Allwinner A64 timer instability · c950ca8c
      由 Samuel Holland 提交于 
      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: NMarc 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#L272Acked-by: NMaxime Ripard <maxime.ripard@bootlin.com>
Tested-by: NAndre Przywara <andre.przywara@arm.com>
Signed-off-by: NSamuel Holland <samuel@sholland.org>
Cc: stable@vger.kernel.org
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
      c950ca8c
  35. 19 12月, 2018 5 次提交
    • M
      clocksource/drivers/rda: Add clock driver for RDA8810PL SoC · 7f83a132
      由 Manivannan Sadhasivam 提交于 
      Add clock driver for RDA Micro RDA8810PL SoC supporting OSTIMER
and HWTIMER.

RDA8810PL has two independent timers: OSTIMER (56 bit) and HWTIMER
(64 bit). Each timer provides optional interrupt support. In this
driver, OSTIMER is used for clockevents and HWTIMER is used for
clocksource.
Signed-off-by: NAndreas Färber <afaerber@suse.de>
Signed-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
      7f83a132
    • A
      clocksource/drivers/riscv_timer: Provide the sched_clock · 92e0d143
      由 Anup Patel 提交于 
      Currently, we don't have a sched_clock registered for RISC-V systems.
This means Linux time keeping will use jiffies (running at HZ) as the
default sched_clock.

To avoid this, we explicity provide sched_clock using RISC-V rdtime
instruction (similar to riscv_timer clocksource).
Signed-off-by: NAnup Patel <anup@brainfault.org>
Reviewed-by: NPalmer Dabbelt <palmer@sifive.com>
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
      92e0d143
    • A
      clocksource/drivers/arc_timer: Utilize generic sched_clock · bf287607
      由 Alexey Brodkin 提交于 
      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: NAlexey 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: NVineet Gupta <vgupta@synopsys.com>
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
      bf287607
    • A
      clocksource/drivers/imx-gpt: Add support for ARM64 · df181e38
      由 Anson Huang 提交于 
      This patch allows building and compile-testing the i.MX GPT driver
also for ARM64. The delay_timer is only supported on ARMv7.
Signed-off-by: NAnson Huang <Anson.Huang@nxp.com>
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
      df181e38
    • L
      clocksource/drivers/ux500: Drop Ux500 custom SCHED_CLOCK · 85b6fcad
      由 Linus Walleij 提交于 
      The two drivers used for Ux500 sched_clock use two Kconfig
symbols to select which of the two gets used as sched_clock.

This isn't right: the workaround is trying to make sure that
the NONSTOP timer is used for sched_clock in order to keep
that clock ticking consistently over a suspend/resume
cycle. (Otherwise sched_clock simply stops during suspend
and continues after resume).

This will notably affect any timetstamped debug prints,
so that they show the absolute number of seconds since the
system was booted and does not loose wall-clock time during
suspend and resume as if time stood still.

The real way to fix this problem is to make sched_clock
take advantage of any NONSTOP clock source on the system
and adjust accordingly, not to try to work around this by
using a different sched_clock depending on what system
we are compiling for. This can solve the problem for
everyone instead of providing a local solution.

Cc: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
      85b6fcad
  37. 03 11月, 2018 2 次提交
  39. 13 8月, 2018 1 次提交
  41. 19 5月, 2018 1 次提交
  43. 31 3月, 2018 1 次提交
  45. 09 3月, 2018 1 次提交
  47. 23 2月, 2018 2 次提交