2010-06-17 15:06:30 simple-gpio
Howard Gordon (UNITED STATES)
Message: 90387
I have visited the various discussions on enabling simple-gpio, but have the same problem discussed elsewhere of not finding a /dev/gpio, even though https://blackfin.uclinux.org/gf/project/uclinux-dist/forum/?action=ForumBrowse&forum_id=39&thread_id=29113&_forum_action=ForumMessageBrowse , even though CONFIG_SIMPLE_GPIO is enabled, and the interface appears in /proc/gpio . What am I missing ? Is there another API I can use to access BF537 GPIO's ?
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2010-06-17 15:11:13 Re: simple-gpio
Peter Naulls (UNITED STATES)
Message: 90388
You can access GPIOs from userspace via /sys. See the end of Documntation/gpio.txt in the kernel source.
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2010-06-17 15:16:58 Re: simple-gpio
Robin Getz (UNITED STATES)
Message: 90389
Howard:
/dev/gpio isn't there anymore -
https://docs.blackfin.uclinux.org/doku.php?id=linux-kernel:drivers:gpio-sysfs
-Robin
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2010-06-17 16:00:37 Re: simple-gpio
Mike Frysinger (UNITED STATES)
Message: 90390
the documentation already says it's dead:
docs.blackfin.uclinux.org/doku.php?id=linux-kernel:drivers:simple-gpio
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2010-06-17 16:04:22 Re: simple-gpio
Howard Gordon (UNITED STATES)
Message: 90391
I should have clarified that I am working from the srv1 patch to 2008R1.5-RC3 which doesn't have gpio-sysfs. We will start moving to the current distribution within the next 1-2 weeks, but I'd like to get this working with the existing code base in the interim.
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2010-06-17 16:13:08 Re: simple-gpio
Robin Getz (UNITED STATES)
Message: 90392
Howard:
We don't support 2008. Current docs, and support is for the latest release only. Right now that is 2009, and soon (in a few months, when we make the 2010 release) it will be 2010 only.
-Robin
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2010-06-17 16:30:22 Re: simple-gpio
Howard Gordon (UNITED STATES)
Message: 90393
Understood - we will be migrating, but I hoped someone might remember how to fix this on 2008 as an interim solution.
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2010-06-17 22:06:52 Re: simple-gpio
Mike Frysinger (UNITED STATES)
Message: 90395
did you follow the documentation about adding the right resources to your board ?
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2010-06-18 11:32:18 Re: simple-gpio
Howard Gordon (UNITED STATES)
Message: 90427
Yes, but I received this warning when compiling -
arch/blackfin/mach-bf537/boards/minotaur.c:139: warning: ‘bfin_gpios_device’ defined but not used
so I'm still missing something.
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2010-06-19 13:06:12 Re: simple-gpio
Mike Frysinger (UNITED STATES)
Message: 90462
simply defining variables doesnt matter if you dont actually hook them up to the platform resources array
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2010-06-19 14:34:44 Re: simple-gpio
Howard Gordon (UNITED STATES)
Message: 90469
Got it. I had to add &bfin_gpios_device to the __initdata array. gpio devices now appear in /dev. However, the actual GPIO bits aren't changing value in response to commands, so maybe there is still a PORT_MUX configuation issue.
root:~> ls /dev
console gpio2 gpio32 gpio45 null ram5 timer7
full gpio20 gpio33 gpio46 ptmx ram6 tty
gpio0 gpio21 gpio34 gpio47 pts ram7 ttyBF0
gpio1 gpio22 gpio35 gpio5 ram0 ram8 ttyBF1
gpio10 gpio23 gpio36 gpio6 ram1 ram9 uinput
gpio11 gpio24 gpio37 gpio7 ram10 random urandom
gpio12 gpio25 gpio38 gpio8 ram11 root video0
gpio13 gpio26 gpio39 gpio9 ram12 timer0 watchdog
gpio14 gpio27 gpio4 i2c-0 ram13 timer1 zero
gpio15 gpio28 gpio40 kmem ram14 timer2
gpio16 gpio29 gpio41 kmsg ram15 timer3
gpio17 gpio3 gpio42 log ram2 timer4
gpio18 gpio30 gpio43 mem ram3 timer5
gpio19 gpio31 gpio44 mtdblock0 ram4 timer6
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2010-06-19 14:58:57 Re: simple-gpio
Howard Gordon (UNITED STATES)
Message: 90470
To clarify, I can change the values of the GPIO bits in the processor, but the bit values don't map to the actual processor pins. So
echo 'O1' > /dev/gpio47
cat /dev/gpio47
111111111111111111111111111111111111111111111111111 ...
echo 'O0' > dev/gpio47
cat /dev/gpio47
00000000000000000000000000000000000000000 ...
However, the voltage on GPIO-H15 never changes.
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2010-06-19 15:19:56 Re: simple-gpio
Mike Frysinger (UNITED STATES)
Message: 90471
please read the documentation with an eye towards the details:
docs.blackfin.uclinux.org/doku.php?id=linux-kernel:drivers:simple-gpio#testing
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2010-06-19 15:54:20 Re: simple-gpio
Howard Gordon (UNITED STATES)
Message: 90472
Right you are. I was following suggestions in the driver source code rather than the docs. Now my LEDs light and my motors change direction. Thanks again.
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