Documentation/dev-tools/gpio-sloppy-logic-analyzer.rst

1 .. SPDX-License-Identifier: GPL-2.0
12 This document briefly describes how to run the GPIO based in-kernel sloppy
19 connected to these GPIO lines with wires (i.e. digital probes), acting as a
22 Another feature is to snoop on on-chip peripherals if the I/O cells of these
26 control subsystem such pin controllers are called "non-strict": a certain pin
31 non-deterministic code paths and non-maskable interrupts. It is called 'sloppy'
39 runtime environment does not utilize cpusets otherwise, then isolation of a CPU
47     i2c-analyzer {
48             compatible = "gpio-sloppy-logic-analyzer";
49             probe-gpios = <&gpio6 21 GPIO_OPEN_DRAIN>, <&gpio6 4 GPIO_OPEN_DRAIN>;
50             probe-names = "SCL", "SDA";
54 maximum of 8 probes are supported. 32 are likely possible but are not
62 ``tools/gpio/gpio-sloppy-logic-analyzer``. Besides checking parameters more
67 snippet which analyzes an I2C bus at 400kHz on a Renesas Salvator-XS board, the
71 sample at least at 800kHz. However, falling edges of both signals in an I2C
73 ``-s 1500000`` for 1.5MHz. Also, we don't want to sample right away but wait
75 edge on SDA while SCL stays high, i.e. ``-t 1H+2F``. Last is the duration, let
76 us assume 15ms here which results in the parameter ``-d 15000``. So,
79     gpio-sloppy-logic-analyzer -s 1500000 -t 1H+2F -d 15000
81 Note that the process will return you back to the prompt but a sub-process is
86     i2cdetect -y -r <your bus number>
88 Result is a .sr file to be consumed with PulseView or sigrok-cli from the free
91 instance name plus a since-epoch timestamp.