[PATCH v13 0/7] gpio-sim: configfs-based GPIO simulator

Bartosz Golaszewski
2021-12-07T09:34:23Z

Hopefully this will be the last iteration of this series. Just some
minor changes requested by Andy in this one.

Tested both with configfs as well as device-tree.

v1 -> v2:
- add selftests for gpio-sim
- add helper programs for selftests
- update the configfs rename callback to work with the new API introduced in
v5.11
- fix a missing quote in the documentation
- use !! whenever using bits operation that are required to return 0 or 1
- use provided bitmap API instead of reimplementing copy or fill operations
- fix a deadlock in gpio_sim_direction_output()
- add new read-only configfs attributes for mapping of configfs items to GPIO
device names
- and address other minor issues pointed out in reviews of v1

v2 -> v3:
- use devm_bitmap_alloc() instead of the zalloc variant if we're initializing
the bitmap with 1s
- drop the patch exporting device_is_bound()
- don't return -ENODEV from dev_nam and chip_name configfs attributes, return
a string indicating that the device is not available yet ('n/a')
- fix indentation where it makes sense
- don't protect IDA functions which use their own locking and where it's not
needed
- use kmemdup() instead of kzalloc() + memcpy()
- collected review tags
- minor coding style fixes

v3 -> v4:
- return 'none' instead of 'n/a' from dev_name and chip_name before the device
is registered
- use sysfs_emit() instead of s*printf()
- drop GPIO_SIM_MAX_PROP as it's only used in an array's definition where it's
fine to hardcode the value

v4 -> v5:
- drop lib patches that are already upstream
- use BIT() instead of (1UL << bit) for flags
- fix refcounting for the configfs_dirent in rename()
- drop d_move() from the rename() callback
- free memory allocated for the live and pending groups in configfs_d_iput()
and not in detach_groups()
- make sure that if a group of some name is in the live directory, a new group
with the same name cannot be created in the pending directory

v5 -> v6:
- go back to using (1UL << bit) instead of BIT()
- if the live group dentry doesn't exist for whatever reason at the time when
mkdir() in the pending group is called (would be a BUG()), return -ENOENT
instead of -EEXIST which should only be returned if given subsystem already
exists in either live or pending group

v6 -> v7:
- as detailed by Andy in commit 6fda593f3082 ("gpio: mockup: Convert to use
software nodes") removing device properties after the platform device is
removed but before the GPIO device gets dropped can lead to a use-after-free
bug - use software nodes to manually control the freeing of the properties

v7 -> v8:
- fixed some minor coding style issues as pointed out by Andy

v8 -> v9:
- dropped the patches implementing committable-items and reworked the
driver to not use them
- reworked the gpio-line-names property and configuring specific lines
in general
- many smaller tweaks here and there

v9 -> v10:
- make writing to 'live' wait for the probe to finish and report an
error to user-space if it failed
- add the ability to hog lines from the kernel-space
- rework locking (drop separate locks for line context objects)
- rework the sysfs interface (create a separate group for each line with
a constant number of attributes instead of going the other way around)

v10 -> v11:
- rework the configfs structure to represent a deeper hierarchy that
gpiolib supports, namely: multiple banks per platform device

v11 -> v12:
- simplify patch 2/7 by removing any mentions of OF from gpiolib.c
- improve the documentation by adding rest markups
- add a device-tree sample to the docs
- drop some trailing whitespaces from the driver
- make gpio_sim_make_bank_swnode() static
- fix coding style in patch 6/7
- add patch 3/7 that makes the OF part of gpiolib prefer to use gpio_chip's fwnode (if set) over of_node

v12 -> v13:
- mentioned ACPI not being converted yet in patch 3/7
- avoided one allocation in gpio_sim_strdup_trimmed() by using memmove()
- use kstrtobool() where applicable
- allow all bases in gpio_sim_bank_config_num_lines_store()
- remove unnecessary commas
- use sysfs_match_string() where applicable
- drop unneeded curr_var local variable

Bartosz Golaszewski (7):
gpiolib: provide gpiod_remove_hogs()
gpiolib: allow to specify the firmware node in struct gpio_chip
gpiolib: of: make fwnode take precedence in struct gpio_chip
gpio: sim: new testing module
selftests: gpio: provide a helper for reading chip info
selftests: gpio: add a helper for reading GPIO line names
selftests: gpio: add test cases for gpio-sim

Documentation/admin-guide/gpio/gpio-sim.rst | 134 ++
drivers/gpio/Kconfig | 8 +
drivers/gpio/Makefile | 1 +
drivers/gpio/gpio-sim.c | 1589 +++++++++++++++++
drivers/gpio/gpiolib-of.c | 3 +
drivers/gpio/gpiolib.c | 18 +-
include/linux/gpio/driver.h | 2 +
include/linux/gpio/machine.h | 2 +
tools/testing/selftests/gpio/.gitignore | 2 +
tools/testing/selftests/gpio/Makefile | 4 +-
tools/testing/selftests/gpio/config | 1 +
tools/testing/selftests/gpio/gpio-chip-info.c | 57 +
tools/testing/selftests/gpio/gpio-line-name.c | 55 +
tools/testing/selftests/gpio/gpio-sim.sh | 396 ++++
14 files changed, 2269 insertions(+), 3 deletions(-)
create mode 100644 Documentation/admin-guide/gpio/gpio-sim.rst
create mode 100644 drivers/gpio/gpio-sim.c
create mode 100644 tools/testing/selftests/gpio/gpio-chip-info.c
create mode 100644 tools/testing/selftests/gpio/gpio-line-name.c
create mode 100755 tools/testing/selftests/gpio/gpio-sim.sh

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2.25.1