kernel/drivers/clocksource/Kconfig, branch linux-5.1.y

clocksource/drivers/npcm: select TIMER_OF

2019-04-11T20:13:43Z

When this is disabled, we get a link failure: drivers/clocksource/timer-npcm7xx.o: In function `npcm7xx_timer_init': timer-npcm7xx.c:(.init.text+0xf): undefined reference to `timer_of_init' Fixes: 1c00289ecd12 ("clocksource/drivers/npcm: Add NPCM7xx timer driver") Signed-off-by: Arnd Bergmann Signed-off-by: Daniel Lezcano

Merge tag 'armsoc-newsoc' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc

2019-03-06T18:15:42Z

Pull ARM new SoC family support from Arnd Bergmann: "Two new SoC families are added this time. Sugaya Taichi submitted support for the Milbeaut SoC family from Socionext and explains: "SC2000 is a SoC of the Milbeaut series. equipped with a DSP optimized for computer vision. It also features advanced functionalities such as 360-degree, real-time spherical stitching with multi cameras, image stabilization for without mechanical gimbals, and rolling shutter correction. More detail is below: https://www.socionext.com/en/products/assp/milbeaut/SC2000.html" Interestingly, this one has a history dating back to older chips made by Socionext and previously Matsushita/Panasonic based on their own mn10300 CPU architecture that was removed from the kernel last year. Manivannan Sadhasivam adds support for another SoC family, this is the Bitmain BM1880 chip used in the Sophon Edge TPU developer board. The chip is intended for Deep Learning applications, and comes with dual-core Arm Cortex-A53 to run Linux as well as a RISC-V microcontroller core to control the tensor unit. For the moment, the TPU is not accessible in mainline Linux, so we treat it as a generic Arm SoC. More information is available at https://www.sophon.ai/" * tag 'armsoc-newsoc' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: ARM: multi_v7_defconfig: add ARCH_MILBEAUT and ARCH_MILBEAUT_M10V ARM: configs: Add Milbeaut M10V defconfig ARM: dts: milbeaut: Add device tree set for the Milbeaut M10V board clocksource/drivers/timer-milbeaut: Introduce timer for Milbeaut SoCs dt-bindings: timer: Add Milbeaut M10V timer description ARM: milbeaut: Add basic support for Milbeaut m10v SoC dt-bindings: Add documentation for Milbeaut SoCs dt-bindings: arm: Add SMP enable-method for Milbeaut dt-bindings: sram: milbeaut: Add binding for Milbeaut smp-sram MAINTAINERS: Add entry for Bitmain SoC platform arm64: dts: bitmain: Add Sophon Egde board support arm64: dts: bitmain: Add BM1880 SoC support arm64: Add ARCH_BITMAIN platform dt-bindings: arm: Document Bitmain BM1880 SoC

clocksource/drivers/timer-milbeaut: Introduce timer for Milbeaut SoCs

2019-03-01T14:18:27Z

Add timer driver for Milbeaut SoCs series. The timer has two 32-bit width down counters, one of which is configured as a clockevent device and the other is configured as a clock source. Signed-off-by: Sugaya Taichi Acked-by: Daniel Lezcano Signed-off-by: Arnd Bergmann

clocksource/drivers/tegra: Add Tegra210 timer support

2019-02-23T11:13:45Z

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 Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Joseph Lo Acked-by: Thierry Reding Acked-by: Jon Hunter Acked-by: Daniel Lezcano Signed-off-by: Daniel Lezcano

clocksource/drivers/arch_timer: Workaround for Allwinner A64 timer instability

2019-02-23T11:13:45Z

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: Marc Zyngier ======================================================================== 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#L272 Acked-by: Maxime Ripard Tested-by: Andre Przywara Signed-off-by: Samuel Holland Cc: stable@vger.kernel.org Signed-off-by: Daniel Lezcano

clocksource/drivers/rda: Add clock driver for RDA8810PL SoC

2018-12-18T21:22:23Z

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: Andreas Färber Signed-off-by: Manivannan Sadhasivam Signed-off-by: Daniel Lezcano

clocksource/drivers/riscv_timer: Provide the sched_clock

2018-12-18T21:22:23Z

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: Anup Patel Reviewed-by: Palmer Dabbelt Signed-off-by: Daniel Lezcano

clocksource/drivers/arc_timer: Utilize generic sched_clock

2018-12-18T21:22:23Z

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: Alexey Brodkin Cc: Daniel Lezcano Cc: Vineet Gupta Cc: Thomas Gleixner Cc: stable@vger.kernel.org Acked-by: Vineet Gupta Signed-off-by: Daniel Lezcano

clocksource/drivers/imx-gpt: Add support for ARM64

2018-12-18T21:22:23Z

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: Anson Huang Signed-off-by: Daniel Lezcano

clocksource/drivers/ux500: Drop Ux500 custom SCHED_CLOCK

2018-12-18T21:22:23Z

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 Signed-off-by: Linus Walleij Signed-off-by: Daniel Lezcano