On Wed, Apr 27, 2016 at 6:00 PM, Michael Welling [off-list ref] wrote:

On Tue, Apr 26, 2016 at 10:54:26AM +0200, Linus Walleij wrote:

quoted

The gpio-hammer is used from userspace as an example of how
to retrieve a GPIO handle for one or several GPIO lines and
hammer the outputs from low to high and back again. It will
pulse the selected lines once per second for a specified
number of times or indefinitely if no loop count is
supplied.

Example output:
$ gpio-hammer -n gpiochip0 -o5 -o6 -o7
Hammer lines [5, 6, 7] on gpiochip0, initial states: [1, 1, 1]
[-] [5: 0, 6: 0, 7: 0]

Signed-off-by: Linus Walleij <redacted>

Tested-by: Michael Welling <redacted>

Thanks! :)

Below is the output from my target.

You can now get rid of all the "unnamed" in the first column
by supplying the line/rail names in gpio-line-names = "A", "B" ...;
in the GPIO controller node in the device tree for the platform,
if it uses device tree too boot.

You will notice that a kernel warning is
spewed out if I use the mcp23s08.
The processor GPIOs work fine as verified by blinking LEDs.

root@som3517-som200:~# ./lsgpio
GPIO chip: gpiochip4, "mcp23s08", 8 GPIO lines
        line  0: unnamed unused
        line  1: unnamed unused
        line  2: unnamed unused
        line  3: unnamed unused
        line  4: unnamed unused
        line  5: unnamed unused
        line  6: unnamed unused
        line  7: unnamed unused

root@som3517-som200:~# ./gpio-hammer -n gpiochip4 -o0
[  187.511606] ------------[ cut here ]------------
[  187.516949] WARNING: CPU: 0 PID: 830 at /home/michael/projects/linux/linux-git/drivers/gpio/gpiolib.c:1907 gpiod_get_value+0x60/0xa4

Ah that's right, I have to use gpiod_get_value_cansleep(). Will
fix that.

Yours,
Linus Walleij