RasPi GPIO driver

[Alan Cudmore]

Yes, I believe you can mix POSIX and Classic RTEMS threads:
http://www.rtems.com/ml/rtems-users/2013/august/msg00097.html

Alan


On 10/20/2013 6:46 PM, sarraciro wrote:
> sorry ... I forgot..
> Another question is: Can I mix POSIX threads with normal threads??
>
> --
> RC
> Il giorno lun, 21/10/2013 alle 00.19 +0200, sarraciro ha scritto:
>> Hi Alan,
>> yes I've tested it too and work properly...
>> for compile using your rki-project makefile (as starting point) I had to
>> add the POSIX support in the makefile...(RTEMS_HAS_POSIX_API = yes after
>> paths for RTEMS tools and RTEMS BSP).
>> But ... it use posix support ... There is another way?? like ChibiOS ???
>>
>> I've read an article about minimum constrains to compile C code in bare
>> metal OS ...
>> I think the solution is something like this:
>>
>> /* mmio.h - access to MMIO registers */
>>   
>> #ifndef MMIO_H
>> #define MMIO_H
>>   
>> #include <stdint.h>
>>   
>> // write to MMIO register
>> static inline void mmio_write(uint32_t reg, uint32_t data) {
>>      uint32_t *ptr = (uint32_t*)reg;
>>      asm volatile("str %[data], [%[reg]]"
>> 	     : : [reg]"r"(ptr), [data]"r"(data));
>> }
>>   
>> // read from MMIO register
>> static inline uint32_t mmio_read(uint32_t reg) {
>>      uint32_t *ptr = (uint32_t*)reg;
>>      uint32_t data;
>>      asm volatile("ldr %[data], [%[reg]]"
>> 		 : [data]"=r"(data) : [reg]"r"(ptr));
>>      return data;
>> }
>>   
>> #endif // #ifndef MMIO_H
>>
>> anyone can confirm or disagree with this?
>> The ": :" or ":" are not C operators true?? sounds like C++?
>>
>> --
>> RC (popovich)
>>
>>
>> Il giorno dom, 20/10/2013 alle 18.05 -0400, Alan Cudmore ha scritto:
>>> There is an RTEMS Rpi GPIO driver here:
>>> https://github.com/pficheux/raspberry_pi/tree/master/RTEMS/gpio_driver
>>> I have tested this, and it works.
>>>
>>> Simon, I will definitely check out your driver when you submit it.
>>>
>>> Alan
>>>
>>> On 10/20/2013 5:57 PM, sarraciro wrote:
>>>> Thank you Simon for your prompt reply... sure that I'm interested!
>>>> I'll wait for the patch! but also I'm trying to learn (understand!?!)
>>>> how to write  a simple driver for RTEMS... for other future use of a
>>>> custom drivers.
>>>> regards
>>>>
>>>> --
>>>> RC
>>>>    
>>>> Il giorno dom, 20/10/2013 alle 21.32 +0000, williamssimonp at gmail.com ha
>>>> scritto:
>>>>> I am testing one as we speak, if you’re interested.  Should be ready
>>>>> to submit the patch about mid-week.
>>>>>    
>>>>> Regards
>>>>>    
>>>>> Simon
>>>>>    
>>>>> Sent from Windows Mail
>>>>>    
>>>>> From: sarraciro
>>>>> Sent: ‎Sunday‎, ‎20‎ ‎October‎ ‎2013 ‎22‎:‎28
>>>>> To: rtems-users at rtems.org
>>>>>    
>>>>> Hi all,
>>>>> I'm trying to write a simple driver to use raspberry pi gpio.
>>>>> I've found some examples for the POSIX approach (& I tried it with
>>>>> success) but I'm more interesting to pure C solution.
>>>>> I read the RTEMS's documentation but it's too general (for my
>>>>> know-how) ... and  I've read the BCM2835 datasheet for register
>>>>> addresses ...  I understood the relevance to use the pointers for
>>>>> access
>>>>> to the memory...but I'm stucking until now I don't understand how to
>>>>> move on...
>>>>> Any suggestions or lectures for understand how to complete the task?
>>>>> thank you
>>>>> rc
>>>>>
>>>>> _______________________________________________
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>>>>> rtems-users at rtems.org
>>>>> http://www.rtems.org/mailman/listinfo/rtems-users
>>>>>
>>>>
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