Merge tag 'gpio-updates-for-v6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux

Pull gpio updates from Bartosz Golaszewski:
 "The biggest feature is the locking overhaul. Up until now the
  synchronization in the GPIO subsystem was broken. There was a single
  spinlock "protecting" multiple data structures but doing it wrong (as
  evidenced by several places where it would be released when a sleeping
  function was called and then reacquired without checking the protected
  state).

  We tried to use an RW semaphore before but the main issue with GPIO is
  that we have drivers implementing the interfaces in both sleeping and
  non-sleeping ways as well as user-facing interfaces that can be called
  both from process as well as atomic contexts. Both ends converge in
  the same code paths that can use neither spinlocks nor mutexes. The
  only reasonable way out is to use SRCU and go mostly lockless. To that
  end: we add several SRCU structs in relevant places and use them to
  assure consistency between API calls together with atomic reads and
  writes of GPIO descriptor flags where it makes sense.

  This code has spent several weeks in next and has received several
  fixes in the first week or two after which it stabilized nicely. The
  GPIO subsystem is now resilient to providers being suddenly unbound.
  We managed to also remove the existing character device RW semaphore
  and the obsolete global spinlock.

  Other than the locking rework we have one new driver (for Chromebook
  EC), much appreciated documentation improvements from Kent and the
  regular driver improvements, DT-bindings updates and GPIOLIB core
  tweaks.

  Serialization rework:
   - use SRCU to serialize access to the global GPIO device list, to
     GPIO device structs themselves and to GPIO descriptors
   - make the GPIO subsystem resilient to the GPIO providers being
     unbound while the API calls are in progress
   - don't dereference the SRCU-protected chip pointer if the
     information we need can be obtained from the GPIO device structure
   - move some of the information contained in struct gpio_chip to
     struct gpio_device to further reduce the need to dereference the
     former
   - pass the GPIO device struct instead of the GPIO chip to sysfs
     callback to, again, reduce the need for accessing the latter
   - get GPIO descriptors from the GPIO device, not from the chip for
     the same reason
   - allow for mostly lockless operation of the GPIO driver API: assure
     consistency with SRCU and atomic operations
   - remove the global GPIO spinlock
   - remove the character device RW semaphore

  Core GPIOLIB:
   - constify pointers in GPIO API where applicable
   - unify the GPIO counting APIs for ACPI and OF
   - provide a macro for iterating over all GPIOs, not only the ones
     that are requested
   - remove leftover typedefs
   - pass the consumer device to GPIO core in
     devm_fwnode_gpiod_get_index() for improved logging
   - constify the GPIO bus type
   - don't warn about removing GPIO chips with descriptors still held by
     users as we can now handle this situation gracefully
   - remove unused logging helpers
   - unexport functions that are only used internally in the GPIO
     subsystem
   - set the device type (assign the relevant struct device_type) for
     GPIO devices

  New drivers:
   - add the ChromeOS EC GPIO driver

  Driver improvements:
   - allow building gpio-vf610 with COMPILE_TEST as well as disabling it
     in menuconfig (before it was always built for i.MX cofigs)
   - count the number of EICs using the device properties instead of
     hard-coding it in gpio-eic-sprd
   - improve the device naming, extend the debugfs output and add
     lockdep asserts to gpio-sim

  DT bindings:
   - document the 'label' property for gpio-pca9570
   - convert aspeed,ast2400-gpio bindings to DT schema
   - disallow unevaluated properties for gpio-mvebu
   - document a new model in renesas,rcar-gpio

  Documentation:
   - improve the character device kerneldocs in user-space headers
   - add proper documentation for the character device uAPI (both v1 and v2)
   - move the sysfs and gpio-mockup docs into the "obsolete" section
   - improve naming consistency for GPIO terms
   - clarify the line values description for sysfs
   - minor docs improvements
   - improve the driver API contract for setting GPIO direction
   - mark unsafe APIs as deprecated in kerneldocs and suggest
     replacements

  Other:
   - remove an obsolete test from selftests"

* tag 'gpio-updates-for-v6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux: (79 commits)
  gpio: sysfs: repair export returning -EPERM on 1st attempt
  selftest: gpio: remove obsolete gpio-mockup test
  gpiolib: Deduplicate cleanup for-loop in gpiochip_add_data_with_key()
  dt-bindings: gpio: aspeed,ast2400-gpio: Convert to DT schema
  gpio: acpi: Make acpi_gpio_count() take firmware node as a parameter
  gpio: of: Make of_gpio_get_count() take firmware node as a parameter
  gpiolib: Pass consumer device through to core in devm_fwnode_gpiod_get_index()
  gpio: sim: use for_each_hwgpio()
  gpio: provide for_each_hwgpio()
  gpio: don't warn about removing GPIO chips with active users anymore
  gpio: sim: delimit the fwnode name with a ":" when generating labels
  gpio: sim: add lockdep asserts
  gpio: Add ChromeOS EC GPIO driver
  gpio: constify of_phandle_args in of_find_gpio_device_by_xlate()
  gpio: fix memory leak in gpiod_request_commit()
  gpio: constify opaque pointer "data" in gpio_device_find()
  gpio: cdev: fix a NULL-pointer dereference with DEBUG enabled
  gpio: uapi: clarify default_values being logical
  gpio: sysfs: fix inverted pointer logic
  gpio: don't let lockdep complain about inherently dangerous RCU usage
  ...

1 files changed, 33 insertions, 30 deletions

diff --git a/include/uapi/linux/gpio.h b/include/uapi/linux/gpio.h
index cb9966d49a16..f7cb8ae87df7 100644
--- a/include/uapi/linux/gpio.h
+++ b/include/uapi/linux/gpio.h
@@ -67,7 +67,7 @@ struct gpiochip_info {
  * @GPIO_V2_LINE_FLAG_BIAS_DISABLED: line has bias disabled
  * @GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME: line events contain REALTIME timestamps
  * @GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE: line events contain timestamps from
- * hardware timestamp engine
+ * the hardware timestamping engine (HTE) subsystem
  */
 enum gpio_v2_line_flag {
 	GPIO_V2_LINE_FLAG_USED			= _BITULL(0),
@@ -88,10 +88,10 @@ enum gpio_v2_line_flag {
 /**
  * struct gpio_v2_line_values - Values of GPIO lines
  * @bits: a bitmap containing the value of the lines, set to 1 for active
- * and 0 for inactive.
+ * and 0 for inactive
  * @mask: a bitmap identifying the lines to get or set, with each bit
  * number corresponding to the index into &struct
- * gpio_v2_line_request.offsets.
+ * gpio_v2_line_request.offsets
  */
 struct gpio_v2_line_values {
 	__aligned_u64 bits;
@@ -123,7 +123,7 @@ enum gpio_v2_line_attr_id {
  * @values: if id is %GPIO_V2_LINE_ATTR_ID_OUTPUT_VALUES, a bitmap
  * containing the values to which the lines will be set, with each bit
  * number corresponding to the index into &struct
- * gpio_v2_line_request.offsets.
+ * gpio_v2_line_request.offsets
  * @debounce_period_us: if id is %GPIO_V2_LINE_ATTR_ID_DEBOUNCE, the
  * desired debounce period, in microseconds
  */
@@ -143,7 +143,7 @@ struct gpio_v2_line_attribute {
  * @attr: the configurable attribute
  * @mask: a bitmap identifying the lines to which the attribute applies,
  * with each bit number corresponding to the index into &struct
- * gpio_v2_line_request.offsets.
+ * gpio_v2_line_request.offsets
  */
 struct gpio_v2_line_config_attribute {
 	struct gpio_v2_line_attribute attr;
@@ -178,7 +178,7 @@ struct gpio_v2_line_config {
  * associated GPIO chip
  * @consumer: a desired consumer label for the selected GPIO lines such as
  * "my-bitbanged-relay"
- * @config: requested configuration for the lines.
+ * @config: requested configuration for the lines
  * @num_lines: number of lines requested in this request, i.e. the number
  * of valid fields in the %GPIO_V2_LINES_MAX sized arrays, set to 1 to
  * request a single line
@@ -189,9 +189,8 @@ struct gpio_v2_line_config {
  * buffer. If this field is zero then the buffer size defaults to a minimum
  * of @num_lines * 16.
  * @padding: reserved for future use and must be zero filled
- * @fd: if successful this field will contain a valid anonymous file handle
- * after a %GPIO_GET_LINE_IOCTL operation, zero or negative value means
- * error
+ * @fd: after a successful %GPIO_V2_GET_LINE_IOCTL operation, contains
+ * a valid anonymous file descriptor representing the request
  */
 struct gpio_v2_line_request {
 	__u32 offsets[GPIO_V2_LINES_MAX];
@@ -217,7 +216,7 @@ struct gpio_v2_line_request {
  * @num_attrs: the number of attributes in @attrs
  * @flags: flags for this GPIO line, with values from &enum
  * gpio_v2_line_flag, such as %GPIO_V2_LINE_FLAG_ACTIVE_LOW,
- * %GPIO_V2_LINE_FLAG_OUTPUT etc, added together.
+ * %GPIO_V2_LINE_FLAG_OUTPUT etc, added together
  * @attrs: the configuration attributes associated with the line
  * @padding: reserved for future use
  */
@@ -274,7 +273,7 @@ enum gpio_v2_line_event_id {
 
 /**
  * struct gpio_v2_line_event - The actual event being pushed to userspace
- * @timestamp_ns: best estimate of time of event occurrence, in nanoseconds.
+ * @timestamp_ns: best estimate of time of event occurrence, in nanoseconds
  * @id: event identifier with value from &enum gpio_v2_line_event_id
  * @offset: the offset of the line that triggered the event
  * @seqno: the sequence number for this event in the sequence of events for
@@ -289,6 +288,10 @@ enum gpio_v2_line_event_id {
  *
  * If the %GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME flag is set then the
  * @timestamp_ns is read from %CLOCK_REALTIME.
+ *
+ * If the %GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE flag is set then the
+ * @timestamp_ns is provided by the hardware timestamping engine (HTE)
+ * subsystem.
  */
 struct gpio_v2_line_event {
 	__aligned_u64 timestamp_ns;
@@ -330,7 +333,7 @@ struct gpio_v2_line_event {
  * also be empty if the consumer doesn't set this up
  *
  * Note: This struct is part of ABI v1 and is deprecated.
- * Use &struct gpio_v2_line_info instead.
+ * Use ABI v2 and &struct gpio_v2_line_info instead.
  */
 struct gpioline_info {
 	__u32 line_offset;
@@ -365,7 +368,7 @@ enum {
  * at the end of the structure on 64-bit architectures.
  *
  * Note: This struct is part of ABI v1 and is deprecated.
- * Use &struct gpio_v2_line_info_changed instead.
+ * Use ABI v2 and &struct gpio_v2_line_info_changed instead.
  */
 struct gpioline_info_changed {
 	struct gpioline_info info;
@@ -396,18 +399,17 @@ struct gpioline_info_changed {
  * a batch of input or output lines, but they must all have the same
  * characteristics, i.e. all inputs or all outputs, all active low etc
  * @default_values: if the %GPIOHANDLE_REQUEST_OUTPUT is set for a requested
- * line, this specifies the default output value, should be 0 (low) or
- * 1 (high), anything else than 0 or 1 will be interpreted as 1 (high)
+ * line, this specifies the default output value, should be 0 (inactive) or
+ * 1 (active).  Anything other than 0 or 1 will be interpreted as active.
  * @consumer_label: a desired consumer label for the selected GPIO line(s)
  * such as "my-bitbanged-relay"
  * @lines: number of lines requested in this request, i.e. the number of
  * valid fields in the above arrays, set to 1 to request a single line
- * @fd: if successful this field will contain a valid anonymous file handle
- * after a %GPIO_GET_LINEHANDLE_IOCTL operation, zero or negative value
- * means error
+ * @fd: after a successful %GPIO_GET_LINEHANDLE_IOCTL operation, contains
+ * a valid anonymous file descriptor representing the request
  *
  * Note: This struct is part of ABI v1 and is deprecated.
- * Use &struct gpio_v2_line_request instead.
+ * Use ABI v2 and &struct gpio_v2_line_request instead.
  */
 struct gpiohandle_request {
 	__u32 lineoffsets[GPIOHANDLES_MAX];
@@ -424,12 +426,12 @@ struct gpiohandle_request {
  * %GPIOHANDLE_REQUEST_OUTPUT, %GPIOHANDLE_REQUEST_ACTIVE_LOW etc, added
  * together
  * @default_values: if the %GPIOHANDLE_REQUEST_OUTPUT is set in flags,
- * this specifies the default output value, should be 0 (low) or
- * 1 (high), anything else than 0 or 1 will be interpreted as 1 (high)
+ * this specifies the default output value, should be 0 (inactive) or
+ * 1 (active).  Anything other than 0 or 1 will be interpreted as active.
  * @padding: reserved for future use and should be zero filled
  *
  * Note: This struct is part of ABI v1 and is deprecated.
- * Use &struct gpio_v2_line_config instead.
+ * Use ABI v2 and &struct gpio_v2_line_config instead.
  */
 struct gpiohandle_config {
 	__u32 flags;
@@ -441,10 +443,11 @@ struct gpiohandle_config {
  * struct gpiohandle_data - Information of values on a GPIO handle
  * @values: when getting the state of lines this contains the current
  * state of a line, when setting the state of lines these should contain
- * the desired target state
+ * the desired target state.  States are 0 (inactive) or 1 (active).
+ * When setting, anything other than 0 or 1 will be interpreted as active.
  *
  * Note: This struct is part of ABI v1 and is deprecated.
- * Use &struct gpio_v2_line_values instead.
+ * Use ABI v2 and &struct gpio_v2_line_values instead.
  */
 struct gpiohandle_data {
 	__u8 values[GPIOHANDLES_MAX];
@@ -465,12 +468,11 @@ struct gpiohandle_data {
  * %GPIOEVENT_REQUEST_RISING_EDGE or %GPIOEVENT_REQUEST_FALLING_EDGE
  * @consumer_label: a desired consumer label for the selected GPIO line(s)
  * such as "my-listener"
- * @fd: if successful this field will contain a valid anonymous file handle
- * after a %GPIO_GET_LINEEVENT_IOCTL operation, zero or negative value
- * means error
+ * @fd: after a successful %GPIO_GET_LINEEVENT_IOCTL operation, contains a
+ * valid anonymous file descriptor representing the request
  *
  * Note: This struct is part of ABI v1 and is deprecated.
- * Use &struct gpio_v2_line_request instead.
+ * Use ABI v2 and &struct gpio_v2_line_request instead.
  */
 struct gpioevent_request {
 	__u32 lineoffset;
@@ -489,10 +491,11 @@ struct gpioevent_request {
 /**
  * struct gpioevent_data - The actual event being pushed to userspace
  * @timestamp: best estimate of time of event occurrence, in nanoseconds
- * @id: event identifier
+ * @id: event identifier, one of %GPIOEVENT_EVENT_RISING_EDGE or
+ *  %GPIOEVENT_EVENT_FALLING_EDGE
  *
  * Note: This struct is part of ABI v1 and is deprecated.
- * Use &struct gpio_v2_line_event instead.
+ * Use ABI v2 and &struct gpio_v2_line_event instead.
  */
 struct gpioevent_data {
 	__u64 timestamp;