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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-24 08:46:03 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-24 08:46:03 -0700 |
| commit | cf9610f9116d55c5a66ef9f1faecacabd93a9322 (patch) | |
| tree | 757a3d280760c654767631cab5ad8af2d86d1848 /Documentation/driver-api/ptp.rst | |
| download | linux-stable-cf9610f9116d55c5a66ef9f1faecacabd93a9322.tar.gz linux-stable-cf9610f9116d55c5a66ef9f1faecacabd93a9322.zip | |
Merge tag 'pinctrl-v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrlgrafted
Pull pin control updates from Linus Walleij:
"Core changes:
- Use the non-blocking mux_state_try_select() in the generic MUX pin
control back-end
- Free pin maps on pinctrl_generic_to_map() failure in the core
helpers
New hardware pin control:
- Qualcomm Maili TLMM SoC, PMG1110 PMIC, and Eliza LPASS LPI TLMM SoC
(this is for the low power audio, LPASS = Low Power Audio SubSystem
portions)
- Upboard support on top of the Intel pin controller
- Apple T6030 and T6031 support (just compatible strings)
- Samsung Exynos 8855 SoC
- Mediatek MT6858 SoC
- Rockchip RK3308B and RV1106 SoCs
- Airoha EN7523 and AN7563 SoCs
Improvements:
- Qualcomm TLMM GPIOs are unconditionally marked as wakeup capable
- Qualcomm improvements on top of the Qualcomm PDC (power domain
controller) irqchip improvements from tglx:s tree
- Qualcomm IPQ806x and IPQ9650 non-urgent pin grop fixups
- The NPCM8xx driver has been put into shape fixing many pin and
group definitions
- Some non-urgent Tegra 264 pin assignments are fixed up
- Some non-urgent fixups to Airoha AN7581 and AN7583 registers and
pin assignments, missing features etc"
* tag 'pinctrl-v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl: (130 commits)
dt-bindings: pinctrl: Convert TI DA850 pupd to DT schema
pinctrl: meson: sync some modify from A4
pinctrl: meson: a4: Add input enable pin configuration
pinctrl: realtek: rtd1625: remove unused group name spdif_sel
pinctrl: realtek: rtd1625: fix base_bit for VE4 GPIO 13
dt-bindings: pinctrl: microchip,pic32mzda-pinctrl: Convert to DT schema
Revert "Merge branch 'ib-rsk7204' into devel"
pinctrl: rockchip: Add RV1106 pinctrl support
dt-bindings: pinctrl: rockchip: Add RV1106 compatible
pinctrl: rockchip: Decode drive strength in the get function
pinctrl: fix PINCTRL_GENERIC_MUX not always being selectable
pinctrl: airoha: add support of an7563 SoC
dt-bindings: pinctrl: airoha: add support of an7563 pin controller
pinctrl: airoha: try to find chip scu node by phandle first
pinctrl: airoha: add support of en7523 SoC
dt-bindings: pinctrl: airoha: add support of en7523 pin controller
pinctrl: airoha: an7583: add support for olt pinmux
pinctrl: airoha: an7583: add support for pon_alt pinmux
pinctrl: airoha: an7583: add support for npu_uart pinmux
dt-bindings: pinctrl: airoha: an7583: add missed features
...
Diffstat (limited to 'Documentation/driver-api/ptp.rst')
| -rw-r--r-- | Documentation/driver-api/ptp.rst | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/Documentation/driver-api/ptp.rst b/Documentation/driver-api/ptp.rst new file mode 100644 index 000000000..5e033c3b1 --- /dev/null +++ b/Documentation/driver-api/ptp.rst @@ -0,0 +1,137 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=========================================== +PTP hardware clock infrastructure for Linux +=========================================== + + This patch set introduces support for IEEE 1588 PTP clocks in + Linux. Together with the SO_TIMESTAMPING socket options, this + presents a standardized method for developing PTP user space + programs, synchronizing Linux with external clocks, and using the + ancillary features of PTP hardware clocks. + + A new class driver exports a kernel interface for specific clock + drivers and a user space interface. The infrastructure supports a + complete set of PTP hardware clock functionality. + + + Basic clock operations + - Set time + - Get time + - Shift the clock by a given offset atomically + - Adjust clock frequency + + + Ancillary clock features + - Time stamp external events + - Period output signals configurable from user space + - Low Pass Filter (LPF) access from user space + - Synchronization of the Linux system time via the PPS subsystem + +PTP hardware clock kernel API +============================= + + A PTP clock driver registers itself with the class driver. The + class driver handles all of the dealings with user space. The + author of a clock driver need only implement the details of + programming the clock hardware. The clock driver notifies the class + driver of asynchronous events (alarms and external time stamps) via + a simple message passing interface. + + The class driver supports multiple PTP clock drivers. In normal use + cases, only one PTP clock is needed. However, for testing and + development, it can be useful to have more than one clock in a + single system, in order to allow performance comparisons. + +PTP hardware clock user space API +================================= + + The class driver also creates a character device for each + registered clock. User space can use an open file descriptor from + the character device as a POSIX clock id and may call + clock_gettime, clock_settime, and clock_adjtime. These calls + implement the basic clock operations. + + User space programs may control the clock using standardized + ioctls. A program may query, enable, configure, and disable the + ancillary clock features. User space can receive time stamped + events via blocking read() and poll(). + +Writing clock drivers +===================== + + Clock drivers include include/linux/ptp_clock_kernel.h and register + themselves by presenting a 'struct ptp_clock_info' to the + registration method. Clock drivers must implement all of the + functions in the interface. If a clock does not offer a particular + ancillary feature, then the driver should just return -EOPNOTSUPP + from those functions. + + Drivers must ensure that all of the methods in interface are + reentrant. Since most hardware implementations treat the time value + as a 64 bit integer accessed as two 32 bit registers, drivers + should use spin_lock_irqsave/spin_unlock_irqrestore to protect + against concurrent access. This locking cannot be accomplished in + class driver, since the lock may also be needed by the clock + driver's interrupt service routine. + +PTP hardware clock requirements for '.adjphase' +----------------------------------------------- + + The 'struct ptp_clock_info' interface has a '.adjphase' function. + This function has a set of requirements from the PHC in order to be + implemented. + + * The PHC implements a servo algorithm internally that is used to + correct the offset passed in the '.adjphase' call. + * When other PTP adjustment functions are called, the PHC servo + algorithm is disabled. + + **NOTE:** '.adjphase' is not a simple time adjustment functionality + that 'jumps' the PHC clock time based on the provided offset. It + should correct the offset provided using an internal algorithm. + +Supported hardware +================== + + * Freescale eTSEC gianfar + + - 2 Time stamp external triggers, programmable polarity (opt. interrupt) + - 2 Alarm registers (optional interrupt) + - 3 Periodic signals (optional interrupt) + + * National DP83640 + + - 6 GPIOs programmable as inputs or outputs + - 6 GPIOs with dedicated functions (LED/JTAG/clock) can also be + used as general inputs or outputs + - GPIO inputs can time stamp external triggers + - GPIO outputs can produce periodic signals + - 1 interrupt pin + + * Intel IXP465 + + - Auxiliary Slave/Master Mode Snapshot (optional interrupt) + - Target Time (optional interrupt) + + * Renesas (IDT) ClockMatrix™ + + - Up to 4 independent PHC channels + - Integrated low pass filter (LPF), access via .adjPhase (compliant to ITU-T G.8273.2) + - Programmable output periodic signals + - Programmable inputs can time stamp external triggers + - Driver and/or hardware configuration through firmware (idtcm.bin) + - LPF settings (bandwidth, phase limiting, automatic holdover, physical layer assist (per ITU-T G.8273.2)) + - Programmable output PTP clocks, any frequency up to 1GHz (to other PHY/MAC time stampers, refclk to ASSPs/SoCs/FPGAs) + - Lock to GNSS input, automatic switching between GNSS and user-space PHC control (optional) + + * NVIDIA Mellanox + + - GPIO + - Certain variants of ConnectX-6 Dx and later products support one + GPIO which can time stamp external triggers and one GPIO to produce + periodic signals. + - Certain variants of ConnectX-5 and older products support one GPIO, + configured to either time stamp external triggers or produce + periodic signals. + - PHC instances + - All ConnectX devices have a free-running counter + - ConnectX-6 Dx and later devices have a UTC format counter |
