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authorLinus Torvalds <torvalds@linux-foundation.org>2021-06-30 11:15:39 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-06-30 11:15:39 -0700
commit776ba3ad659e4955079f57f8d859e7994ea35076 (patch)
tree18b27ed3684dfbe1c1ee2d4b54706657c551b346 /Documentation/driver-api
parentebb81c14543fb43cb2e1f2bfb5d32f5e390cf895 (diff)
parent0e695c3f7f66c66e0a1da90cc5378198a656d494 (diff)
Merge tag 'platform-drivers-x86-v5.14-1' of git://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86
Pull x86 platform driver updates from Hans de Goede: "Highlights: - New think-lmi driver adding support for changing Lenovo Thinkpad BIOS settings from within Linux using the standard firmware- attributes class sysfs API - MS Surface aggregator-cdev now also supports forwarding events to user-space (for debugging / new driver development purposes only) - New intel_skl_int3472 driver this provides the necessary glue to translate ACPI table information to GPIOs, regulators, etc. for camera sensors on Intel devices with IPU3 attached MIPI cameras - A whole bunch of other fixes + device-specific quirk additions - New devm_work_autocancel() devm-helpers.h function" * tag 'platform-drivers-x86-v5.14-1' of git://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86: (83 commits) platform/x86: dell-wmi-sysman: Change user experience when Admin/System Password is modified platform/x86: intel_skl_int3472: Uninitialized variable in skl_int3472_handle_gpio_resources() platform/x86: think-lmi: Move kfree(setting->possible_values) to tlmi_attr_setting_release() platform/x86: think-lmi: Split current_value to reflect only the value platform/x86: think-lmi: Fix issues with duplicate attributes platform/x86: think-lmi: Return EINVAL when kbdlang gets set to a 0 length string platform/x86: intel_cht_int33fe: Move to its own subfolder platform/x86: intel_skl_int3472: Move to intel/ subfolder platform/x86: intel_skl_int3472: Provide skl_int3472_unregister_clock() platform/x86: intel_skl_int3472: Provide skl_int3472_unregister_regulator() platform/x86: intel_skl_int3472: Use ACPI GPIO resource directly platform/x86: intel_skl_int3472: Fix dependencies (drop CLKDEV_LOOKUP) platform/x86: intel_skl_int3472: Free ACPI device resources after use platform/x86: Remove "default n" entries platform/x86: ISST: Use numa node id for cpu pci dev mapping platform/x86: ISST: Optimize CPU to PCI device mapping tools/power/x86/intel-speed-select: v1.10 release tools/power/x86/intel-speed-select: Fix uncore memory frequency display extcon: extcon-max8997: Simplify driver using devm extcon: extcon-max8997: Fix IRQ freeing at error path ...
Diffstat (limited to 'Documentation/driver-api')
-rw-r--r--Documentation/driver-api/surface_aggregator/clients/cdev.rst127
1 files changed, 122 insertions, 5 deletions
diff --git a/Documentation/driver-api/surface_aggregator/clients/cdev.rst b/Documentation/driver-api/surface_aggregator/clients/cdev.rst
index 248c1372d879..0134a841a079 100644
--- a/Documentation/driver-api/surface_aggregator/clients/cdev.rst
+++ b/Documentation/driver-api/surface_aggregator/clients/cdev.rst
@@ -1,9 +1,8 @@
.. SPDX-License-Identifier: GPL-2.0+
-.. |u8| replace:: :c:type:`u8 <u8>`
-.. |u16| replace:: :c:type:`u16 <u16>`
.. |ssam_cdev_request| replace:: :c:type:`struct ssam_cdev_request <ssam_cdev_request>`
.. |ssam_cdev_request_flags| replace:: :c:type:`enum ssam_cdev_request_flags <ssam_cdev_request_flags>`
+.. |ssam_cdev_event| replace:: :c:type:`struct ssam_cdev_event <ssam_cdev_event>`
==============================
User-Space EC Interface (cdev)
@@ -23,6 +22,40 @@ These IOCTLs and their respective input/output parameter structs are defined in
A small python library and scripts for accessing this interface can be found
at https://github.com/linux-surface/surface-aggregator-module/tree/master/scripts/ssam.
+.. contents::
+
+
+Receiving Events
+================
+
+Events can be received by reading from the device-file. The are represented by
+the |ssam_cdev_event| datatype.
+
+Before events are available to be read, however, the desired notifiers must be
+registered via the ``SSAM_CDEV_NOTIF_REGISTER`` IOCTL. Notifiers are, in
+essence, callbacks, called when the EC sends an event. They are, in this
+interface, associated with a specific target category and device-file-instance.
+They forward any event of this category to the buffer of the corresponding
+instance, from which it can then be read.
+
+Notifiers themselves do not enable events on the EC. Thus, it may additionally
+be necessary to enable events via the ``SSAM_CDEV_EVENT_ENABLE`` IOCTL. While
+notifiers work per-client (i.e. per-device-file-instance), events are enabled
+globally, for the EC and all of its clients (regardless of userspace or
+non-userspace). The ``SSAM_CDEV_EVENT_ENABLE`` and ``SSAM_CDEV_EVENT_DISABLE``
+IOCTLs take care of reference counting the events, such that an event is
+enabled as long as there is a client that has requested it.
+
+Note that enabled events are not automatically disabled once the client
+instance is closed. Therefore any client process (or group of processes) should
+balance their event enable calls with the corresponding event disable calls. It
+is, however, perfectly valid to enable and disable events on different client
+instances. For example, it is valid to set up notifiers and read events on
+client instance ``A``, enable those events on instance ``B`` (note that these
+will also be received by A since events are enabled/disabled globally), and
+after no more events are desired, disable the previously enabled events via
+instance ``C``.
+
Controller IOCTLs
=================
@@ -45,9 +78,33 @@ The following IOCTLs are provided:
- ``REQUEST``
- Perform synchronous SAM request.
+ * - ``0xA5``
+ - ``2``
+ - ``W``
+ - ``NOTIF_REGISTER``
+ - Register event notifier.
-``REQUEST``
------------
+ * - ``0xA5``
+ - ``3``
+ - ``W``
+ - ``NOTIF_UNREGISTER``
+ - Unregister event notifier.
+
+ * - ``0xA5``
+ - ``4``
+ - ``W``
+ - ``EVENT_ENABLE``
+ - Enable event source.
+
+ * - ``0xA5``
+ - ``5``
+ - ``W``
+ - ``EVENT_DISABLE``
+ - Disable event source.
+
+
+``SSAM_CDEV_REQUEST``
+---------------------
Defined as ``_IOWR(0xA5, 1, struct ssam_cdev_request)``.
@@ -82,6 +139,66 @@ submitted, and completed (i.e. handed back to user-space) successfully from
inside the IOCTL, but the request ``status`` member may still be negative in
case the actual execution of the request failed after it has been submitted.
-A full definition of the argument struct is provided below:
+A full definition of the argument struct is provided below.
+
+``SSAM_CDEV_NOTIF_REGISTER``
+----------------------------
+
+Defined as ``_IOW(0xA5, 2, struct ssam_cdev_notifier_desc)``.
+
+Register a notifier for the event target category specified in the given
+notifier description with the specified priority. Notifiers registration is
+required to receive events, but does not enable events themselves. After a
+notifier for a specific target category has been registered, all events of that
+category will be forwarded to the userspace client and can then be read from
+the device file instance. Note that events may have to be enabled, e.g. via the
+``SSAM_CDEV_EVENT_ENABLE`` IOCTL, before the EC will send them.
+
+Only one notifier can be registered per target category and client instance. If
+a notifier has already been registered, this IOCTL will fail with ``-EEXIST``.
+
+Notifiers will automatically be removed when the device file instance is
+closed.
+
+``SSAM_CDEV_NOTIF_UNREGISTER``
+------------------------------
+
+Defined as ``_IOW(0xA5, 3, struct ssam_cdev_notifier_desc)``.
+
+Unregisters the notifier associated with the specified target category. The
+priority field will be ignored by this IOCTL. If no notifier has been
+registered for this client instance and the given category, this IOCTL will
+fail with ``-ENOENT``.
+
+``SSAM_CDEV_EVENT_ENABLE``
+--------------------------
+
+Defined as ``_IOW(0xA5, 4, struct ssam_cdev_event_desc)``.
+
+Enable the event associated with the given event descriptor.
+
+Note that this call will not register a notifier itself, it will only enable
+events on the controller. If you want to receive events by reading from the
+device file, you will need to register the corresponding notifier(s) on that
+instance.
+
+Events are not automatically disabled when the device file is closed. This must
+be done manually, via a call to the ``SSAM_CDEV_EVENT_DISABLE`` IOCTL.
+
+``SSAM_CDEV_EVENT_DISABLE``
+---------------------------
+
+Defined as ``_IOW(0xA5, 5, struct ssam_cdev_event_desc)``.
+
+Disable the event associated with the given event descriptor.
+
+Note that this will not unregister any notifiers. Events may still be received
+and forwarded to user-space after this call. The only safe way of stopping
+events from being received is unregistering all previously registered
+notifiers.
+
+
+Structures and Enums
+====================
.. kernel-doc:: include/uapi/linux/surface_aggregator/cdev.h