[PATCH v5 0/1] gpio: add simple logic analyzer using polling

[Wolfram Sang]

The bravery continues with the next update of the in-kernel logic
analyzer based on GPIO polling with local irqs disabled. It has been
tested locally and remotely. It provided satisfactory results. Besides
the driver, there is also a script which isolates a CPU to achieve the
best possible result. I am aware of the latency limitations. However,
the intention is for debugging only, not mass production. Especially for
remote debugging and to get a first impression, this has already been
useful. Documentation is within the patch, to get a better idea what
this is all about.

A branch is here:
git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git renesas/gpio-logic-analyzer-v5

And an eLinux-wiki page with a picture of a result is here:
https://elinux.org/Kernel_GPIO_Logic_analyzer

Changes since last version:
* increased version number to 5 to match internal and external numbering
* added "SLOPPY" to the Kconfig symbol as well
* addressed Geert's comments (typos and more 'unsigned int' usage).
  Thanks!
* addressed Andy's comments (updated comment, use dev_err_probe, use
  '... || fail' pattern in script consequently). Thanks!

I've used the analyzer in a few more scenarios and on another SoC
(Renesas R-Car M3-W) and was happy with the outcome. Looking forward to
other tests and comments. From my side this is good to go.

Happy hacking,

   Wolfram


Wolfram Sang (1):
  gpio: add sloppy logic analyzer using polling

 .../dev-tools/gpio-sloppy-logic-analyzer.rst  |  71 ++++
 Documentation/dev-tools/index.rst             |   1 +
 drivers/gpio/Kconfig                          |  17 +
 drivers/gpio/Makefile                         |   1 +
 drivers/gpio/gpio-sloppy-logic-analyzer.c     | 340 ++++++++++++++++++
 tools/gpio/gpio-sloppy-logic-analyzer         | 222 ++++++++++++
 6 files changed, 652 insertions(+)
 create mode 100644 Documentation/dev-tools/gpio-sloppy-logic-analyzer.rst
 create mode 100644 drivers/gpio/gpio-sloppy-logic-analyzer.c
 create mode 100755 tools/gpio/gpio-sloppy-logic-analyzer

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2.30.2