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 * AI Coding Assistant - LLMs and AI-powered development tools 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 AI Coding Assistant ------------------- CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and follow the AI coding assistants documentation before contributing to the Linux kernel: * Documentation/process/coding-assistants.rst This documentation contains essential requirements about licensing, attribution, and the Developer Certificate of Origin that all AI tools must comply with. 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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Add device IDs of Nova Lake into i2c-usbio support list
Signed-off-by: Arun T <arun.t@intel.com>
Reviewed-by: Vadillo Miguel <miguel.vadillo@intel.com>
Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260410080408.562311-1-arun.t@intel.com
In GPI mode, the I2C GENI driver programs an extra TX DMA transfer
descriptor (TRE) on the TX channel when handling a single read message.
This results in an unintended write phase being issued on the I2C bus,
even though a read transaction does not require any TX data.
For a single-byte read, the correct hardware sequence consists of the
CONFIG and GO commands followed by a single RX DMA TRE. Programming an
additional TX DMA TRE is redundant, causes unnecessary DMA buffer
mapping on the TX channel, and may lead to incorrect bus behavior.
Update the transfer logic to avoid programming a TX DMA TRE for single
read messages in GPI mode.
Co-developed-by: Maramaina Naresh <naresh.maramaina@oss.qualcomm.com>
Signed-off-by: Maramaina Naresh <naresh.maramaina@oss.qualcomm.com>
Signed-off-by: Aniket Randive <aniket.randive@oss.qualcomm.com>
Reviewed-by: Mukesh Kumar Savaliya <mukesh.savaliya@oss.qualcomm.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260410101949.2315058-1-aniket.randive@oss.qualcomm.com
Convert kzalloc_obj + kcalloc to kzalloc_flex to save an allocation.
Add __counted_by to get extra runtime analysis.
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260327030310.8502-1-rosenp@gmail.com
This patch introduces I2C PIO functionality for the Spacemit K1 SoC,
enabling the use of I2C in atomic context.
When i2c xfer_atomic is invoked, use_pio is set accordingly.
Since an atomic context is required, all interrupts are disabled when
operating in PIO mode. Even with interrupts disabled, the bits in the
ISR (Interrupt Status Register) will still be set, so error handling can
be performed by polling the relevant status bits in the ISR.
Signed-off-by: Troy Mitchell <troy.mitchell@linux.spacemit.com>
Tested-by: Aurelien Jarno <aurelien@aurel32.net>
Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260207-b4-k3-i2c-pio-v7-2-626942d94d91@linux.spacemit.com
The upcoming PIO support requires a wait_pio_xfer() helper, which is
invoked from xfer_msg().
Since wait_pio_xfer() depends on err_check(), move the definition of
xfer_msg() after err_check() to avoid a forward declaration of
err_check().
Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Reviewed-by: Alex Elder <elder@riscstar.com>
Signed-off-by: Troy Mitchell <troy.mitchell@linux.spacemit.com>
Tested-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260207-b4-k3-i2c-pio-v7-1-626942d94d91@linux.spacemit.com
Currently Linux does not implement ACPI ClockInput() resource to describe
clocks, unlike DT. However the xiic driver is happy if something
magically enables the clock before the driver probes, and does not
turn it off again. The clock should always be considered optional for
ACPI.
Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260223-i2c-xiic-v12-7-b6c9ce4e4f3c@nexthop.ai
Switch from i2c_add_adapter() to i2c_add_numbered_adapter() to enable
platforms to specify fixed I2C bus numbers via the platform device ID.
This allows systems to maintain consistent bus numbering across reboots.
On platforms where the device ID is PLATFORM_DEVID_NONE (the default),
the adapter falls back to dynamic allocation, preserving backward
compatibility.
Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260223-i2c-xiic-v12-6-b6c9ce4e4f3c@nexthop.ai
Use standard resource format specifier %pR in debug log.
Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260223-i2c-xiic-v12-5-b6c9ce4e4f3c@nexthop.ai
Re-use dev pointer instead of referencing &pdev->dev everywhere.
Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260223-i2c-xiic-v12-4-b6c9ce4e4f3c@nexthop.ai
Use generic device property accessors making them work for ACPI
platforms.
Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260223-i2c-xiic-v12-3-b6c9ce4e4f3c@nexthop.ai
The devm_request_threaded_irq() already prints an error message. Remove
the duplicate.
Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260223-i2c-xiic-v12-2-b6c9ce4e4f3c@nexthop.ai
Simplify the error code paths by switching to devres managed helper
functions.
Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260223-i2c-xiic-v12-1-b6c9ce4e4f3c@nexthop.ai
Add support for the internal I2C controllers of RTL9607C series based
SoCs. Add register definitions, chip-specific functions and macros too.
Make use of the clk introduced from the previous patch to get the clk_div
value and use it during the rtl9607c channel configuration.
Introduce a new EXT_SCK_5MS field to the reg fields struct which is going
to be initialized by rtl9607c init function at the end of the probe.
This patch depends on all the previous patches in this patch series.
Signed-off-by: Rustam Adilov <adilov@disroot.org>
Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260401180648.337834-9-adilov@disroot.org
Due to the very nature of differences between RTL9607C i2c controller
and RTL9300 / RTL9310 that are incompatible with each other in some areas
of this driver, for example in clock configuration, channel configuration
and initialization at the end of the probe, introduce new function
properties to the driver data struct to handle those differences.
With these new properties, create configuration functions for RTL9300 and
RTL9310 and assign them to their respective driver data structs.
Signed-off-by: Rustam Adilov <adilov@disroot.org>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260401180648.337834-8-adilov@disroot.org
In RTL9607C i2c controller, there is 10 bit CLK_DIV field for
setting the clock of i2c interface which depends on the rate
of i2c clk (which seems be fixed to 62.5MHz according to Realtek SDK).
Introduce the clk struct and the respective F_CLK_DIV and clk_div
which are going to be used in the upcoming patch for rtl9607c i2c
controller support addition.
devm_clk_get_optional_enabled() function was used for cleaner code
as it automatically returns NULL if the clk is not present, which is
going to be the case for RTL9300 and RTL9310 i2c controllers.
Signed-off-by: Rustam Adilov <adilov@disroot.org>
Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260401180648.337834-7-adilov@disroot.org
Add the "realtek,rtl9607-i2c" compatible for i2c controller on the
RTL9607C SoC series.
Add a clocks property to the properties to describe the i2c reference
clock and make it available for all the compatibles. This i2c reference
clock is assumed to be coming from switchcore region via Lexra bus as
the other SoC peripherals.
According to the info available about the existing devices, they also
have the i2c master controller clocks.
RTL9607C requires the "realtek,scl" and "clocks" to be specified
and so handle it under separate if check for "realtek,rtl9607-i2c".
Signed-off-by: Rustam Adilov <adilov@disroot.org>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260401180648.337834-6-adilov@disroot.org