Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. Quick Start ----------- * Report a bug: See Documentation/admin-guide/reporting-issues.rst * Get the latest kernel: https://kernel.org * Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst * Join the community: https://lore.kernel.org/ Essential Documentation ----------------------- All users should be familiar with: * Building requirements: Documentation/process/changes.rst * Code of Conduct: Documentation/process/code-of-conduct.rst * License: See COPYING Documentation can be built with make htmldocs or viewed online at: https://www.kernel.org/doc/html/latest/ Who Are You? ============ Find your role below: * New Kernel Developer - Getting started with kernel development * Academic Researcher - Studying kernel internals and architecture * Security Expert - Hardening and vulnerability analysis * Backport/Maintenance Engineer - Maintaining stable kernels * System Administrator - Configuring and troubleshooting * Maintainer - Leading subsystems and reviewing patches * Hardware Vendor - Writing drivers for new hardware * Distribution Maintainer - Packaging kernels for distros For Specific Users ================== New Kernel Developer -------------------- Welcome! Start your kernel development journey here: * Getting Started: Documentation/process/development-process.rst * Your First Patch: Documentation/process/submitting-patches.rst * Coding Style: Documentation/process/coding-style.rst * Build System: Documentation/kbuild/index.rst * Development Tools: Documentation/dev-tools/index.rst * Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst * Core APIs: Documentation/core-api/index.rst Academic Researcher ------------------- Explore the kernel's architecture and internals: * Researcher Guidelines: Documentation/process/researcher-guidelines.rst * Memory Management: Documentation/mm/index.rst * Scheduler: Documentation/scheduler/index.rst * Networking Stack: Documentation/networking/index.rst * Filesystems: Documentation/filesystems/index.rst * RCU (Read-Copy Update): Documentation/RCU/index.rst * Locking Primitives: Documentation/locking/index.rst * Power Management: Documentation/power/index.rst Security Expert --------------- Security documentation and hardening guides: * Security Documentation: Documentation/security/index.rst * LSM Development: Documentation/security/lsm-development.rst * Self Protection: Documentation/security/self-protection.rst * Reporting Vulnerabilities: Documentation/process/security-bugs.rst * CVE Procedures: Documentation/process/cve.rst * Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst * Security Features: Documentation/userspace-api/seccomp_filter.rst Backport/Maintenance Engineer ----------------------------- Maintain and stabilize kernel versions: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * Backporting Guide: Documentation/process/backporting.rst * Applying Patches: Documentation/process/applying-patches.rst * Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git for Maintainers: Documentation/maintainer/configure-git.rst System Administrator -------------------- Configure, tune, and troubleshoot Linux systems: * Admin Guide: Documentation/admin-guide/index.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst * Tracing/Debugging: Documentation/trace/index.rst * Performance Security: Documentation/admin-guide/perf-security.rst * Hardware Monitoring: Documentation/hwmon/index.rst Maintainer ---------- Lead kernel subsystems and manage contributions: * Maintainer Handbook: Documentation/maintainer/index.rst * Pull Requests: Documentation/maintainer/pull-requests.rst * Managing Patches: Documentation/maintainer/modifying-patches.rst * Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst * Development Process: Documentation/process/maintainer-handbooks.rst * Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git Configuration: Documentation/maintainer/configure-git.rst Hardware Vendor --------------- Write drivers and support new hardware: * Driver API Guide: Documentation/driver-api/index.rst * Driver Model: Documentation/driver-api/driver-model/driver.rst * Device Drivers: Documentation/driver-api/infrastructure.rst * Bus Types: Documentation/driver-api/driver-model/bus.rst * Device Tree Bindings: Documentation/devicetree/bindings/ * Power Management: Documentation/driver-api/pm/index.rst * DMA API: Documentation/core-api/dma-api.rst Distribution Maintainer ----------------------- Package and distribute the kernel: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * ABI Documentation: Documentation/ABI/README * Kernel Configuration: Documentation/kbuild/kconfig.rst * Module Signing: Documentation/admin-guide/module-signing.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst Communication and Support ========================= * Mailing Lists: https://lore.kernel.org/ * IRC: #kernelnewbies on irc.oftc.net * Bugzilla: https://bugzilla.kernel.org/ * MAINTAINERS file: Lists subsystem maintainers and mailing lists * Email Clients: Documentation/process/email-clients.rst
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Simplify the TEE implementor ID match by returning the boolean
expression directly instead of going through an if/else.
Signed-off-by: Rouven Czerwinski <rouven.czerwinski@linaro.org>
Link: https://patch.msgid.link/20260126-optee-simplify-context-match-v1-3-d4104e526cb6@linaro.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Commit 795cda8338ea ("rtc: interface: Fix long-standing race when setting
alarm") should not discard any errors from the preceding validations.
Prior to that commit, if the alarm feature was disabled, or the
set_alarm failed, a meaningful error code would be returned to the
caller for further action.
After, more often than not, the __rtc_read_time will cause a success
return code instead, misleading the caller.
An example of this is when timer_enqueue is called for a rtc-abx080x
device. Since that driver does not clear the alarm feature bit, but
instead relies on the set_alarm operation to return invalid, the discard
of the return code causes very different behaviour; i.e.
hwclock: select() to /dev/rtc0 to wait for clock tick timed out
Fixes: 795cda8338ea ("rtc: interface: Fix long-standing race when setting alarm")
Signed-off-by: Anthony Pighin (Nokia) <anthony.pighin@nokia.com>
Reviewed-by: Esben Haabendal <esben@geanix.com>
Tested-by: Nick Bowler <nbowler@draconx.ca>
Link: https://patch.msgid.link/BN0PR08MB6951415A751F236375A2945683D1A@BN0PR08MB6951.namprd08.prod.outlook.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
This RTC has one "free" register which can be used to store arbitrary
data. Expose it as a nvmem resource in Linux.
Signed-off-by: Lorenz Brun <lorenz@monogon.tech>
Link: https://patch.msgid.link/20251223125728.346073-1-lorenz@monogon.tech
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
The Loongson-2K0300's rtc hardware design is similar to that of the
Loongson-1B, but it does not support the alarm feature.
Introduce `LOONGSON_RTC_ALARM_WORKAROUND`, which indicates a chip that
does not support the alarm feature, and rewrite the related logic in
`loongson_rtc_alarm_setting()`.
Reviewed-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Link: https://patch.msgid.link/abff68dda2fe6a6601a9e58b31e278d941297fce.1768616276.git.zhoubinbin@loongson.cn
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Add "loongson,ls2k0300-rtc" dedicated compatible to represent the RTC
interface of the Loongson-2K0300 chip.
Its hardware design is similar to that of the Loongson-1B, but it does
not support the alarm feature.
Reviewed-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://patch.msgid.link/0c6a4fd221b5bf05f06cae9bb543a5bf7ea59f57.1768616276.git.zhoubinbin@loongson.cn
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
The `interrupts` property indicates an RTC alarm interrupt, which is
required for RTCs that support the alarm feature, which is not supported
by the Loongson-1C RTC. We exclude it for a more accurate description.
Changing the `allowed` property is ABI-breaking behavior, but
throughout the existing Loongson DTS{i}, the description of the RTC
nodes conforms to the modified bingding rules.
Thus, the existing Loongson DTS{i} will not be affected.
Fixes: 487ef32caebe ("dt-bindings: rtc: Split loongson,ls2x-rtc into SoC-based compatibles")
Reviewed-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://patch.msgid.link/b6295c907410f6708115cba4df0959ee6629f8a5.1768616276.git.zhoubinbin@loongson.cn
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
The Renesas RZ/V2N (r9a09g056) RTC is identical to the RZ/V2H
(r9a09g057) variant. Add the compatible string for RZ/V2N and
extend the existing RZ/V2H reset configuration to cover both
variants.
Signed-off-by: Ovidiu Panait <ovidiu.panait.rb@renesas.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/20260125192706.27099-4-ovidiu.panait.rb@renesas.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Convert RTC devicetree bindings for the Motorola CPCAP MFD from TXT to
YAML format. This patch does not change any functionality; the bindings
remain the same.
Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
Link: https://patch.msgid.link/20260125134302.45958-7-clamor95@gmail.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Maximum and minimum offsets in ppb that can be handled are dependent on
the rtc clock frequency and what can fit in the 16-bit register field.
Reviewed-by: Harini T <harini.t@amd.com>
Tested-by: Harini T <harini.t@amd.com>
Signed-off-by: Tomas Melin <tomas.melin@vaisala.com>
Acked-by: Michal Simek <michal.simek@amd.com>
Link: https://patch.msgid.link/20260122-zynqmp-rtc-updates-v4-5-d4edb966b499@vaisala.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
set_offset was using remainder of do_div as tick_mult which resulted in
wrong offset. Calibration value also assumed builtin calibration default.
Update fract_offset to correctly calculate the value for
negative offset and replace the for loop with division.
Tested-by: Harini T <harini.t@amd.com>
Signed-off-by: Tomas Melin <tomas.melin@vaisala.com>
Reviewed-by: Harini T <harini.t@amd.com>
Acked-by: Michal Simek <michal.simek@amd.com>
Link: https://patch.msgid.link/20260122-zynqmp-rtc-updates-v4-4-d4edb966b499@vaisala.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
read_offset() was using static frequency for determining
the tick offset. It was also using remainder from do_div()
operation as tick_mult value which caused the offset to be
incorrect.
At the same time, rework function to improve readability.
It is worth noting, that due to rounding errors, the offset
readback will differ slightly for positive and negative
calibration values.
Reviewed-by: Harini T <harini.t@amd.com>
Tested-by: Harini T <harini.t@amd.com>
Signed-off-by: Tomas Melin <tomas.melin@vaisala.com>
Acked-by: Michal Simek <michal.simek@amd.com>
Link: https://patch.msgid.link/20260122-zynqmp-rtc-updates-v4-3-d4edb966b499@vaisala.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Enable check to not overflow the calibration
max value.
Reviewed-by: Harini T <harini.t@amd.com>
Tested-by: Harini T <harini.t@amd.com>
Signed-off-by: Tomas Melin <tomas.melin@vaisala.com>
Acked-by: Michal Simek <michal.simek@amd.com>
Link: https://patch.msgid.link/20260122-zynqmp-rtc-updates-v4-2-d4edb966b499@vaisala.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Fix calibration value in case a clock reference is provided.
The actual calibration value written into register is
frequency - 1.
Reviewed-by: Harini T <harini.t@amd.com>
Tested-by: Harini T <harini.t@amd.com>
Signed-off-by: Tomas Melin <tomas.melin@vaisala.com>
Acked-by: Michal Simek <michal.simek@amd.com>
Link: https://patch.msgid.link/20260122-zynqmp-rtc-updates-v4-1-d4edb966b499@vaisala.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Passing IRQF_ONESHOT ensures that the interrupt source is masked until
the secondary (threaded) handler is done. If only a primary handler is
used then the flag makes no sense because the interrupt can not fire
(again) while its handler is running.
The flag also disallows force-threading of the primary handler and the
irq-core will warn about this.
Remove IRQF_ONESHOT from irqflags.
Fixes: c89ac9182ee29 ("rtc: support for the Amlogic on-chip RTC")
Reviewed-by: Xianwei Zhao <xianwei.zhao@amlogic.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20260128095540.863589-13-bigeasy@linutronix.de
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
When switching to regmap, the i2c_client pointer was removed from struct
pcf8563 so this function switched to using the RTC device instead. But
the RTC device is a child of the original I2C device and does not have
an associated of_node.
Reference the correct device's of_node to ensure that the output clock
can be found when referenced by other devices and so that the override
clock name is read correctly.
Cc: stable@vger.kernel.org
Fixes: 00f1bb9b8486b ("rtc: pcf8563: Switch to regmap")
Signed-off-by: John Keeping <jkeeping@inmusicbrands.com>
Link: https://patch.msgid.link/20260108184749.3413348-1-jkeeping@inmusicbrands.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
IS_REACHABLE() is meant to be used with full symbol names from a kernel
.config file, not the shortened symbols used in Kconfig files, so
change HWMON to CONFIG_HWMON in 3 places.
Fixes: dedaf03b99d6 ("rtc: max31335: add driver support")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Nuno Sá <nuno.sa@analog.com>
Link: https://patch.msgid.link/20260108045432.2705691-1-rdunlap@infradead.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>