| /linux/Documentation/devicetree/bindings/rtc/ |
| H A D | trivial-rtc.yaml | 1 # SPDX-License-Identifier: GPL-2.0
3 ---
4 $id: http://devicetree.org/schemas/rtc/trivial-rtc.yaml#
5 $schema: http://devicetree.org/meta-schemas/core.yaml#
10 - Alexandre Belloni <alexandre.belloni@bootlin.com>
18 - $ref: rtc.yaml#
23 # AB-RTCMC-32.768kHz-B5ZE-S3: Real Time Clock/Calendar Module with I2C Interface
24 - abracon,abb5zes3
25 # AB-RTCMC-32.768kHz-EOZ9: Real Time Clock/Calendar Module with I2C Interface
26 - abracon,abeoz9
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| H A D | microchip,pic32mzda-rtc.yaml | 1 # SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
3 ---
4 $id: http://devicetree.org/schemas/rtc/microchip,pic32mzda-rtc.yaml#
5 $schema: http://devicetree.org/meta-schemas/core.yaml#
7 title: Microchip PIC32 Real Time Clock and Calendar
10 - Alexandre Belloni <alexandre.belloni@bootlin.com>
13 The Microchip PIC32 Real Time Clock and Calendar (RTCC) keeps time in hours,
18 - $ref: rtc.yaml#
22 const: microchip,pic32mzda-rtc
34 - compatible
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| /linux/Documentation/scheduler/ |
| H A D | sched-rt-group.rst | 2 Real-Time group scheduling
12 2.1 System-wide settings
28 resolution, or the time it takes to handle the budget refresh itself.
33 are real-time processes).
40 ---------------
42 Real-time scheduling is all about determinism, a group has to be able to rely on
43 the amount of bandwidth (eg. CPU time) being constant. In order to schedule
44 multiple groups of real-time tasks, each group must be assigned a fixed portion
45 of the CPU time available. Without a minimum guarantee a real-time group can
50 ----------------
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| /linux/Documentation/core-api/real-time/ |
| H A D | kernel-configuration.rst | 1 .. SPDX-License-Identifier: GPL-2.0
4 Real-Time Kernel configuration
15 real-time kernel's worst-case latency. It is intended for system integrators.
23 -----------------------
38 A real-time kernel is not about being "as fast as possible", however
39 real-time requirements may demand that the CPU is clocked at a particular
48 Real-Time workloads expect a fixed CPU frequency during execution. Using the
56 Non-performance CPU frequency governors
63 non-``PERFORMANCE`` CPU frequency governors whenever possible. This avoids
76 The ``ONDEMAND`` governor should not be enabled on a real-time system. Its
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| H A D | hardware.rst | 1 .. SPDX-License-Identifier: GPL-2.0
18 -----------------------
32 project (https://www.open-mpi.org/projects/hwloc/) can visualize the hierarchy.
52 c2c tool can help identify cache-to-cache issues, where multiple CPU
56 --------------
58 Real-time systems often need to access hardware directly to perform their work.
76 requirements of certain real-time use cases.
82 is not limited to PCIe; internal buses within a System-on-Chip (SoC) can also be
86 --------------
89 thread on the host. If such a thread runs with real-time priority, the system
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| /linux/include/linux/mfd/syscon/ |
| H A D | atmel-st.h | 1 /* SPDX-License-Identifier: GPL-2.0+ */
6 * System Timer (ST) - System peripherals registers.
26 #define AT91_ST_RTMR 0x0c /* Real-time Mode Register */
27 #define AT91_ST_RTPRES 0xffff /* Real-time Prescalar Value */
32 #define AT91_ST_RTTINC BIT(2) /* Real-time Timer Increment */
39 #define AT91_ST_RTAR 0x20 /* Real-time Alarm Register */
42 #define AT91_ST_CRTR 0x24 /* Current Real-time Register */
43 #define AT91_ST_CRTV 0xfffff /* Current Real-Time Value */
|
| /linux/drivers/rtc/ |
| H A D | Kconfig | 1 # SPDX-License-Identifier: GPL-2.0-only
14 bool "Real Time Clock"
26 bool "Set system time from RTC on startup and resume"
29 If you say yes here, the system time (wall clock) will be set using
31 unnecessary fsck runs at boot time, and to network better.
34 string "RTC used to set the system time"
41 device should record time in UTC, since the kernel won't do
44 This clock should be battery-backed, so that it reads the correct
45 time when the system boots from a power-off state. Otherwise, your
49 be useful to reinitialize system time when resuming from system
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| H A D | rtc-at91sam9.c | 1 // SPDX-License-Identifier: GPL-2.0+
3 * "RTT as Real Time Clock" driver for AT91SAM9 SoC family
7 * Based on rtc-at91rm9200.c by Rick Bronson
23 #include <linux/time.h>
28 * to implement the Real Time Clock interfaces
30 * - A "Real-time Timer" (RTT) counts up in seconds from a base time.
33 * - One of the "General Purpose Backup Registers" (GPBRs) holds the
34 * base time, normally an offset from the beginning of the POSIX
35 * epoch (1970-Jan-1 00:00:00 UTC). Some systems also include the
42 * choose from, or a "real" RTC module. All systems have multiple GPBR
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| /linux/include/uapi/linux/ |
| H A D | acct.h | 1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
3 * BSD Process Accounting for Linux - Definitions
8 * BSD-style process accounting. The kernel accounting code and all
9 * user-level programs that try to do something useful with the
12 * Copyright (C) 1995 - 1997 Marco van Wieringen - ELM Consultancy B.V.
25 * comp_t is a 16-bit "floating" point number with a 3-bit base 8
26 * exponent and a 13-bit fraction.
27 * comp2_t is 24-bit with 5-bit base 2 exponent and 20 bit fraction
49 __u16 ac_uid16; /* LSB of Real User ID */
50 __u16 ac_gid16; /* LSB of Real Group ID */
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| /linux/kernel/trace/rv/monitors/pagefault/ |
| H A D | Kconfig | 1 # SPDX-License-Identifier: GPL-2.0-only
13 Monitor that real-time tasks do not raise page faults, causing
16 If you are developing a real-time system and not entirely sure whether
17 the applications are designed correctly for real-time, you want to say
|
| /linux/Documentation/sound/designs/ |
| H A D | seq-oss.rst | 15 What this does - it provides the emulation of the OSS sequencer, access
53 However, each MIDI device is exclusive - that is, if a MIDI device
57 * Real-time event processing:
59 The events can be processed in real time without using out of bound
60 ioctl. To switch to real-time mode, send ABSTIME 0 event. The followed
61 events will be processed in real-time without queued. To switch off the
62 real-time mode, send RELTIME 0 event.
67 ``/proc/asound/seq/oss`` at any time. In the later version,
74 Run configure script with both sequencer support (``--with-sequencer=yes``)
75 and OSS emulation (``--with-oss=yes``) options. A module ``snd-seq-oss.o``
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| /linux/Documentation/mm/ |
| H A D | active_mm.rst | 6 (running tasks with ->active_mm == mm && ->mm == NULL) on kernels
13 List: linux-kernel
16 Date: 1999-07-30 21:36:24
18 Cc'd to linux-kernel, because I don't write explanations all that often,
25 > discussed on the mailing lists---I just returned from vacation and
26 > wasn't able to follow linux-kernel for a while).
30 - we have "real address spaces" and "anonymous address spaces". The
32 user-level page tables at all, so when we do a context switch into an
37 doesn't need any user mappings - all kernel threads basically fall into
38 this category, but even "real" threads can temporarily say that for
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| /linux/tools/testing/selftests/damon/ |
| H A D | damon_nr_regions.py | 2 # SPDX-License-Identifier: GPL-2.0
5 import time
14 Exit with non-zero return code if the given {min,max}_nr_regions is not
42 time.sleep(0.1)
66 test_name = 'nr_regions test with %d/%d/%d real/min/max nr_regions' % (
70 collected_nr_regions[-1] > max_nr_regions):
79 # test min_nr_regions larger than real nr regions
82 # test max_nr_regions smaller than real nr regions
85 # test online-tuned max_nr_regions that smaller than real nr regions
107 # wait until the real regions are found
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| /linux/Documentation/timers/ |
| H A D | no_hz.rst | 2 NO_HZ: Reducing Scheduling-Clock Ticks
7 reduce the number of scheduling-clock interrupts, thereby improving energy
9 some types of computationally intensive high-performance computing (HPC)
10 applications and for real-time applications.
12 There are three main ways of managing scheduling-clock interrupts
13 (also known as "scheduling-clock ticks" or simply "ticks"):
15 1. Never omit scheduling-clock ticks (CONFIG_HZ_PERIODIC=y or
16 CONFIG_NO_HZ=n for older kernels). You normally will -not-
19 2. Omit scheduling-clock ticks on idle CPUs (CONFIG_NO_HZ_IDLE=y or
23 3. Omit scheduling-clock ticks on CPUs that are either idle or that
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| /linux/arch/m68k/bvme6000/ |
| H A D | rtc.c | 1 // SPDX-License-Identifier: GPL-2.0
3 * Real Time Clock interface for Linux on the BVME6000
48 case RTC_RD_TIME: /* Read the time/date from RTC */ in rtc_ioctl()
51 /* Ensure clock and real-time-mode-register are accessible */ in rtc_ioctl()
52 msr = rtc->msr & 0xc0; in rtc_ioctl()
53 rtc->msr = 0x40; in rtc_ioctl()
56 wtime.tm_sec = bcd2bin(rtc->bcd_sec); in rtc_ioctl()
57 wtime.tm_min = bcd2bin(rtc->bcd_min); in rtc_ioctl()
58 wtime.tm_hour = bcd2bin(rtc->bcd_hr); in rtc_ioctl()
59 wtime.tm_mday = bcd2bin(rtc->bcd_dom); in rtc_ioctl()
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| /linux/kernel/rcu/ |
| H A D | Kconfig | 1 # SPDX-License-Identifier: GPL-2.0-only
3 # RCU-related configuration options
11 # Dynticks-idle tracking
26 thousands of CPUs, but for which real-time response
37 designed for UP systems from which real-time response
42 bool "Make expert-level adjustments to RCU configuration"
46 expert-level adjustments to RCU configuration. By default,
47 no such adjustments can be made, which has the often-beneficial
48 side-effect of preventing "make oldconfig" from asking you all
52 Say Y if you need to make expert-level adjustments to RCU.
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| /linux/Documentation/driver-api/hte/ |
| H A D | tegra-hte.rst | 1 .. SPDX-License-Identifier: GPL-2.0+
7 -----------
15 --------
17 This GTE instance timestamps GPIO in real time. For that to happen GPIO
19 instance supports timestamping GPIOs in real time as it is tightly coupled with
31 specified during IOCTL calls. Refer to ``tools/gpio/gpio-event-mon.c``, which
35 -----------------------------------------
37 This GTE instance timestamps LIC IRQ lines in real time. The hte devicetree
40 one-to-one mapping with IRQ GTE provider, consumers can simply specify the IRQ
45 ``drivers/hte/hte-tegra194.c``. The test driver
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| /linux/Documentation/admin-guide/ |
| H A D | rtc.rst | 2 Real Time Clock (RTC) Drivers for Linux
5 When Linux developers talk about a "Real Time Clock", they usually mean
6 something that tracks wall clock time and is battery backed so that it
8 the local time zone or daylight savings time -- unless they dual boot
9 with MS-Windows -- but will instead be set to Coordinated Universal Time
10 (UTC, formerly "Greenwich Mean Time").
12 The newest non-PC hardware tends to just count seconds, like the time(2)
13 system call reports, but RTCs also very commonly represent time using
14 the Gregorian calendar and 24 hour time, as reported by gmtime(3).
16 Linux has two largely-compatible userspace RTC API families you may
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| /linux/Documentation/ABI/testing/ |
| H A D | sysfs-class-rtc-rtc0-device-rtc_calibration | 5 Description: Attribute for calibrating ST-Ericsson AB8500 Real Time Clock
7 calibrate the AB8500.s 32KHz Real Time Clock.
11 The range of the attribute is -127 to +127 in units of
12 30.5 micro-seconds (half-parts-per-million of the 32KHz clock)
13 Users: The /vendor/st-ericsson/base_utilities/core/rtc_calibration
|
| /linux/drivers/power/reset/ |
| H A D | at91-poweroff.c | 5 * Copyright (C) 2011 Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
28 #define AT91_SHDW_WKMODE0 GENMASK(2, 0) /* Wake-up 0 Mode Selection */
32 #define AT91_SHDW_RTTWKEN BIT(16) /* Real Time Timer Wake-up Enable */
33 #define AT91_SHDW_RTCWKEN BIT(17) /* Real Time Clock Wake-up Enable */
36 #define AT91_SHDW_WAKEUP0 BIT(0) /* Wake-up 0 Status */
37 #define AT91_SHDW_RTTWK BIT(16) /* Real-time Timer Wake-up */
38 #define AT91_SHDW_RTCWK BIT(17) /* Real-time Clock Wake-up [SAM9RL] */
65 /* Simple power-on, just bail out */ in at91_wakeup_status()
76 dev_info(&pdev->dev, "Wake-Up source: %s\n", reason); in at91_wakeup_status()
110 err = of_property_read_string(np, "atmel,wakeup-mode", &pm); in at91_poweroff_get_wakeup_mode()
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| /linux/Documentation/virt/kvm/x86/ |
| H A D | timekeeping.rst | 1 .. SPDX-License-Identifier: GPL-2.0
4 Timekeeping Virtualization for X86-Based Architectures
23 time introduces a new set of challenges because it introduces a multiplexed
24 division of time beyond the control of the guest CPU.
32 information relevant to KVM and hardware-based virtualization.
41 2.1. i8254 - PIT
42 ----------------
46 channels which can be programmed to deliver periodic or one-shot interrupts.
53 The PIT uses I/O ports 0x40 - 0x43. Access to the 16-bit counters is done
59 -------------- ----------------
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| /linux/kernel/ |
| H A D | Kconfig.preempt | 1 # SPDX-License-Identifier: GPL-2.0-only
30 time, but there are no guarantees and occasional longer delays
60 bool "Preemptible Kernel (Low-Latency Desktop)"
93 bool "Fully Preemptible Kernel (Real-Time)"
97 This option turns the kernel into a real-time kernel by replacing
99 preemptible priority-inheritance aware variants, enforcing
101 non-preemptible sections. This makes the kernel, except for very
107 require real-time guarantees.
114 the softirq is preemptible. This enforces the same per-CPU BLK
115 semantic non-PREEMPT_RT builds have. This should not be needed
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| /linux/Documentation/block/ |
| H A D | bfq-iosched.rst | 5 BFQ is a proportional-share I/O scheduler, with some extra
6 low-latency capabilities. In addition to cgroups support (blkio or io
9 - BFQ guarantees a high system and application responsiveness, and a
10 low latency for time-sensitive applications, such as audio or video
12 - BFQ distributes bandwidth, not just time, among processes or
13 groups (switching back to time distribution when needed to keep
19 goal, for a given device, is to achieve the maximum-possible
20 throughput at all times, then do switch off all low-latency heuristics
25 As every I/O scheduler, BFQ adds some overhead to per-I/O-request
27 single-lock-protected, per-request processing time of BFQ---i.e., the
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| /linux/Documentation/sound/codecs/ |
| H A D | tas675x.rst | 1 .. SPDX-License-Identifier: GPL-2.0
8 4-channel amplifier driver.
17 --------------------
30 PVDD Foldback, Clip Detect) and Real-Time Load Diagnostics unavailable.
33 Reduced latency. Real-Time Load Diagnostics unavailable.
48 ----------------------
53 :Range: -15.5 dB to 0 dB (0.5 dB steps)
57 ---------------------
59 :Description: Anti-pop ramp step duration for analog gain transitions.
66 ---------------------------
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| /linux/include/xen/interface/hvm/ |
| H A D | params.h | 1 /* SPDX-License-Identifier: MIT */
14 * How should CPU0 event-channel notifications be delivered?
16 * If val == 0 then CPU0 event-channel notifications are not delivered.
42 * val[15:8] is interrupt flag of the PPI used by event-channel:
45 * val[7:0] is a PPI number used by event-channel.
63 * Do not advance a vcpu's time beyond the correct delivery time for
66 * time stepwise for each one.
68 * As above, missed interrupts are delivered, but guest time always tracks
69 * wallclock (i.e., real) time while doing so.
72 * delivered at some non-zero rate, if we detect missed ticks then the
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