Lines Matching +full:gpio +full:- +full:lines

1 .. SPDX-License-Identifier: GPL-2.0
4 Linux Kernel GPIO based sloppy logic analyzer
12 This document briefly describes how to run the GPIO based in-kernel sloppy
15 The sloppy logic analyzer will utilize a few GPIO lines in input mode on a
16 system to rapidly sample these digital lines, which will, if the Nyquist
18 appeared on these lines. One way to use it is to analyze external traffic
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
23 peripherals can be used in GPIO input mode at the same time as they are being
26 control subsystem such pin controllers are called "non-strict": a certain pin
27 can be used with a certain peripheral and as a GPIO input line at the same
31 non-deterministic code paths and non-maskable interrupts. It is called 'sloppy'
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";
53 Note that you must provide a name for every GPIO specified. Currently a
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
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.