[Xenomai-help] rtdm_iomap_to_user question

[Xenomai-help] rtdm_iomap_to_user question

[Zhang, Haobo]

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Hi,

I am currently working on a project which is running on a PowerPC
platform. In my rtdm driver, I use "rtdm_iomap_to_user" to map a few I/O
memory locations to be accessed from my application. All the function
calls seem to work (no error code returned). But my application fails to
use these pointers to manipulate any I/O. Is there any restrictions I
have to be aware in order to use those mapped I/O mem? I am new to
xenomai. I would really appreciate any help to this. 

Best Regards,
Haobo Zhang



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Re: [Xenomai-help] rtdm_iomap_to_user question

[Jan Kiszka]

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Zhang, Haobo wrote:
> Hi,
> 
> I am currently working on a project which is running on a PowerPC
> platform. In my rtdm driver, I use "rtdm_iomap_to_user" to map a few I/O
> memory locations to be accessed from my application. All the function
> calls seem to work (no error code returned). But my application fails to
> use these pointers to manipulate any I/O. Is there any restrictions I
> have to be aware in order to use those mapped I/O mem? I am new to
> xenomai. I would really appreciate any help to this. 

Maybe you can post code or relevant code snippets so that we can have a
look. As I personally haven't work with this particular service yet, I
put Stelian in CC who contributed it and might already have some
suggestion. But, again, code talks much more.

Jan


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Re: [Xenomai-help] rtdm_iomap_to_user question

[Zhang, Haobo]

Hi Jan,

Thank you so much for your reply!

In my driver, I wrote:

int map_io( struct gpiodrv_context *dev_context, rtdm_user_info_t
*user_info, struct MAPPED_IO *io )
{
	int ret;

	if ((dev_context == 0) || (user_info == 0) || (io == 0))
		return -EFAULT;

	if (dev_context->mapped_user_info != 0)
	{
		if ((ret = gpio_unmap_io( dev_context )) != 0)
			return ret;
	}

	dev_context->mapped_user_info = user_info;

	ret = rtdm_iomap_to_user( user_info, MPC52xx_PA(
MPC52xx_GPIO_WKUP_OFFSET + 0x0C ),
		1, PROT_READ | PROT_WRITE, (void
**)&(io->gpio_heart_beat), NULL, NULL );
	
	if (ret != 0)
		goto __ERROR;
	else
		dev_context->mapped_heart_beat = (void
*)io->gpio_heart_beat;

	return 0;

__ERROR:

	gpio_unmap_io( dev_context );
	return ret;
} 

In the application, I wrote:

int main(int argc, char *argv[]) 
{
	int dev_gpio;
	struct MAPPED_IO gpio;

	signal(SIGTERM, clean_exit);	
	signal(SIGINT, clean_exit);	
	
	mlockall( MCL_CURRENT | MCL_FUTURE );

	rt_task_shadow( &mainapp, "mainapp", 1, 0 );

	dev_gpio = rt_dev_open( "gpio", 0 );
	if (dev_gpio < 0)
	{
		return -1;
	}
	
	gpio.gpio_heart_beat = NULL;

	if (rt_dev_ioctl( dev_gpio, 1, &gpio ) != 0)
	{
		return -1;
	}

	gpio.gpio_heart_beat[0] = 0x01;

	...
}

I also tried another way by opening "/dev/mem" and then using "mmap" to
map the I/O memory addresses in the application. It worked! 
I am very curious about why "rtdm_iomap_to_user" did not work for me. 

Thanks,
Haobo

-----Original Message-----
From: jan.kiszka@domain.hid [mailto:jan.kiszka@domain.hid
Sent: May 10, 2007 5:40 PM
To: Zhang, Haobo
Cc: xenomai@xenomai.org; stelian@domain.hid
Subject: Re: [Xenomai-help] rtdm_iomap_to_user question

Zhang, Haobo wrote:
> Hi,
> 
> I am currently working on a project which is running on a PowerPC 
> platform. In my rtdm driver, I use "rtdm_iomap_to_user" to map a few 
> I/O memory locations to be accessed from my application. All the 
> function calls seem to work (no error code returned). But my 
> application fails to use these pointers to manipulate any I/O. Is 
> there any restrictions I have to be aware in order to use those mapped

> I/O mem? I am new to xenomai. I would really appreciate any help to
this.

Maybe you can post code or relevant code snippets so that we can have a
look. As I personally haven't work with this particular service yet, I
put Stelian in CC who contributed it and might already have some
suggestion. But, again, code talks much more.

Jan

Re: [Xenomai-help] rtdm_iomap_to_user question

[Jan Kiszka]

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Zhang, Haobo wrote:
> Hi Jan,
> 
> Thank you so much for your reply!
> 
> In my driver, I wrote:
> 
> int map_io( struct gpiodrv_context *dev_context, rtdm_user_info_t
> *user_info, struct MAPPED_IO *io )
> {
> 	int ret;
> 
> 	if ((dev_context == 0) || (user_info == 0) || (io == 0))
> 		return -EFAULT;
> 
> 	if (dev_context->mapped_user_info != 0)
> 	{
> 		if ((ret = gpio_unmap_io( dev_context )) != 0)
> 			return ret;
> 	}
> 
> 	dev_context->mapped_user_info = user_info;
> 
> 	ret = rtdm_iomap_to_user( user_info, MPC52xx_PA(
> MPC52xx_GPIO_WKUP_OFFSET + 0x0C ),
> 		1, PROT_READ | PROT_WRITE, (void
> **)&(io->gpio_heart_beat), NULL, NULL );

Hmm, hmm. Looking at our code and the kernel again I would say we should
catch non-page-aligned requests like this and document this pitfall better.

The mapping code always assumes page-alignment and rounds your physical
address down. So what likely happened here is that you got a mapping,
but with unexpected offset (gpio_heart_beat should point to MPC52xx_PA).

> 	
> 	if (ret != 0)
> 		goto __ERROR;
> 	else
> 		dev_context->mapped_heart_beat = (void
> *)io->gpio_heart_beat;
> 
> 	return 0;
> 
> __ERROR:
> 
> 	gpio_unmap_io( dev_context );
> 	return ret;
> } 
> 
> In the application, I wrote:
> 
> int main(int argc, char *argv[]) 
> {
> 	int dev_gpio;
> 	struct MAPPED_IO gpio;
> 
> 	signal(SIGTERM, clean_exit);	
> 	signal(SIGINT, clean_exit);	
> 	
> 	mlockall( MCL_CURRENT | MCL_FUTURE );
> 
> 	rt_task_shadow( &mainapp, "mainapp", 1, 0 );
> 
> 	dev_gpio = rt_dev_open( "gpio", 0 );
> 	if (dev_gpio < 0)
> 	{
> 		return -1;
> 	}
> 	
> 	gpio.gpio_heart_beat = NULL;
> 
> 	if (rt_dev_ioctl( dev_gpio, 1, &gpio ) != 0)
> 	{
> 		return -1;
> 	}
> 
> 	gpio.gpio_heart_beat[0] = 0x01;
> 
> 	...
> }
> 
> I also tried another way by opening "/dev/mem" and then using "mmap" to
> map the I/O memory addresses in the application. It worked! 
> I am very curious about why "rtdm_iomap_to_user" did not work for me. 

When you do precisely the same odd-numbered mapping via mmap on
/dev/mem, you do get the right address at gpio_heart_beat (check if the
start address ends with 0x0b0c)?

We either have to improve rtdm_iomap/mmap_to_user in this regard or
catch unaligned requests. Probably it's easier to catch it so that the
driver writer also realises that this is always about mapping full pages...

Jan


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Re: [Xenomai-help] rtdm_iomap_to_user question

[Zhang, Haobo]

Thanks, Jan. It is fixed after I modified my code as you suggested.

Best Regards,
Haobo Zhang 

-----Original Message-----
From: jan.kiszka@domain.hid [mailto:jan.kiszka@domain.hid
Sent: May 11, 2007 12:22 PM
To: Zhang, Haobo
Cc: xenomai@xenomai.org; stelian@domain.hid
Subject: Re: [Xenomai-help] rtdm_iomap_to_user question

Zhang, Haobo wrote:
> Hi Jan,
> 
> Thank you so much for your reply!
> 
> In my driver, I wrote:
> 
> int map_io( struct gpiodrv_context *dev_context, rtdm_user_info_t 
> *user_info, struct MAPPED_IO *io ) {
> 	int ret;
> 
> 	if ((dev_context == 0) || (user_info == 0) || (io == 0))
> 		return -EFAULT;
> 
> 	if (dev_context->mapped_user_info != 0)
> 	{
> 		if ((ret = gpio_unmap_io( dev_context )) != 0)
> 			return ret;
> 	}
> 
> 	dev_context->mapped_user_info = user_info;
> 
> 	ret = rtdm_iomap_to_user( user_info, MPC52xx_PA( 
> MPC52xx_GPIO_WKUP_OFFSET + 0x0C ),
> 		1, PROT_READ | PROT_WRITE, (void
> **)&(io->gpio_heart_beat), NULL, NULL );

Hmm, hmm. Looking at our code and the kernel again I would say we should
catch non-page-aligned requests like this and document this pitfall
better.

The mapping code always assumes page-alignment and rounds your physical
address down. So what likely happened here is that you got a mapping,
but with unexpected offset (gpio_heart_beat should point to MPC52xx_PA).

> 	
> 	if (ret != 0)
> 		goto __ERROR;
> 	else
> 		dev_context->mapped_heart_beat = (void
*)io->gpio_heart_beat;
> 
> 	return 0;
> 
> __ERROR:
> 
> 	gpio_unmap_io( dev_context );
> 	return ret;
> }
> 
> In the application, I wrote:
> 
> int main(int argc, char *argv[])
> {
> 	int dev_gpio;
> 	struct MAPPED_IO gpio;
> 
> 	signal(SIGTERM, clean_exit);	
> 	signal(SIGINT, clean_exit);	
> 	
> 	mlockall( MCL_CURRENT | MCL_FUTURE );
> 
> 	rt_task_shadow( &mainapp, "mainapp", 1, 0 );
> 
> 	dev_gpio = rt_dev_open( "gpio", 0 );
> 	if (dev_gpio < 0)
> 	{
> 		return -1;
> 	}
> 	
> 	gpio.gpio_heart_beat = NULL;
> 
> 	if (rt_dev_ioctl( dev_gpio, 1, &gpio ) != 0)
> 	{
> 		return -1;
> 	}
> 
> 	gpio.gpio_heart_beat[0] = 0x01;
> 
> 	...
> }
> 
> I also tried another way by opening "/dev/mem" and then using "mmap" 
> to map the I/O memory addresses in the application. It worked!
> I am very curious about why "rtdm_iomap_to_user" did not work for me. 

When you do precisely the same odd-numbered mapping via mmap on
/dev/mem, you do get the right address at gpio_heart_beat (check if the
start address ends with 0x0b0c)?

We either have to improve rtdm_iomap/mmap_to_user in this regard or
catch unaligned requests. Probably it's easier to catch it so that the
driver writer also realises that this is always about mapping full
pages...

Jan

Re: [Xenomai-help] rtdm_iomap_to_user question

[Jan Kiszka]

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Zhang, Haobo wrote:
> Thanks, Jan. It is fixed after I modified my code as you suggested.

Good to hear. Now just please answer my question below related to
/dev/mem so that I can think about a generic solution for the
documentation or the code or rtdm_*map_to_user.

Jan

> 
> Best Regards,
> Haobo Zhang 
> 
> -----Original Message-----
> From: jan.kiszka@domain.hid [mailto:jan.kiszka@domain.hid
> Sent: May 11, 2007 12:22 PM
> To: Zhang, Haobo
> Cc: xenomai@xenomai.org; stelian@domain.hid
> Subject: Re: [Xenomai-help] rtdm_iomap_to_user question
> 
> Zhang, Haobo wrote:
>> Hi Jan,
>>
>> Thank you so much for your reply!
>>
>> In my driver, I wrote:
>>
>> int map_io( struct gpiodrv_context *dev_context, rtdm_user_info_t 
>> *user_info, struct MAPPED_IO *io ) {
>> 	int ret;
>>
>> 	if ((dev_context == 0) || (user_info == 0) || (io == 0))
>> 		return -EFAULT;
>>
>> 	if (dev_context->mapped_user_info != 0)
>> 	{
>> 		if ((ret = gpio_unmap_io( dev_context )) != 0)
>> 			return ret;
>> 	}
>>
>> 	dev_context->mapped_user_info = user_info;
>>
>> 	ret = rtdm_iomap_to_user( user_info, MPC52xx_PA( 
>> MPC52xx_GPIO_WKUP_OFFSET + 0x0C ),
>> 		1, PROT_READ | PROT_WRITE, (void
>> **)&(io->gpio_heart_beat), NULL, NULL );
> 
> Hmm, hmm. Looking at our code and the kernel again I would say we should
> catch non-page-aligned requests like this and document this pitfall
> better.
> 
> The mapping code always assumes page-alignment and rounds your physical
> address down. So what likely happened here is that you got a mapping,
> but with unexpected offset (gpio_heart_beat should point to MPC52xx_PA).
> 
>> 	
>> 	if (ret != 0)
>> 		goto __ERROR;
>> 	else
>> 		dev_context->mapped_heart_beat = (void
> *)io->gpio_heart_beat;
>> 	return 0;
>>
>> __ERROR:
>>
>> 	gpio_unmap_io( dev_context );
>> 	return ret;
>> }
>>
>> In the application, I wrote:
>>
>> int main(int argc, char *argv[])
>> {
>> 	int dev_gpio;
>> 	struct MAPPED_IO gpio;
>>
>> 	signal(SIGTERM, clean_exit);	
>> 	signal(SIGINT, clean_exit);	
>> 	
>> 	mlockall( MCL_CURRENT | MCL_FUTURE );
>>
>> 	rt_task_shadow( &mainapp, "mainapp", 1, 0 );
>>
>> 	dev_gpio = rt_dev_open( "gpio", 0 );
>> 	if (dev_gpio < 0)
>> 	{
>> 		return -1;
>> 	}
>> 	
>> 	gpio.gpio_heart_beat = NULL;
>>
>> 	if (rt_dev_ioctl( dev_gpio, 1, &gpio ) != 0)
>> 	{
>> 		return -1;
>> 	}
>>
>> 	gpio.gpio_heart_beat[0] = 0x01;
>>
>> 	...
>> }
>>
>> I also tried another way by opening "/dev/mem" and then using "mmap" 
>> to map the I/O memory addresses in the application. It worked!
>> I am very curious about why "rtdm_iomap_to_user" did not work for me. 
> 
> When you do precisely the same odd-numbered mapping via mmap on
> /dev/mem, you do get the right address at gpio_heart_beat (check if the
> start address ends with 0x0b0c)?
> 
> We either have to improve rtdm_iomap/mmap_to_user in this regard or
> catch unaligned requests. Probably it's easier to catch it so that the
> driver writer also realises that this is always about mapping full
> pages...
> 
> Jan
> 



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