MPC5200b kernel module memory mapping

MPC5200b kernel module memory mapping

[Steven Kaiser]

In a kernel module, I am trying to iomemory map or ioport map a range of
addresses so later I can talk directly to custom external hardware.  I have
tried to follow the advice of Rubini chapter 8.  I think I am setting it up
correctly, but at the precise moment I try to write anything within my
range, the kernel crashes badly.  My board is a Lite5200b, using a 2.4.25
kernel.

#define MALab_DEVICE_NAME	"MALab"
#define MALab_MM_START		0x60000000U
#define MALab_MM_END		0x6000ffffU
#define MALab_MM_SIZE		0x00010000U

#define MPC5xxx_MM_CS2_START	(MPC5xxx_MBAR + 0x0014)
#define MPC5xxx_MM_CS2_STOP	(MPC5xxx_MBAR + 0x0018)
#define MPC5xxx_MM_IPBI		(MPC5xxx_MBAR + 0x0054)

void *ioaddr = NULL;

// start 'em up
int init_module(void) {

	register_chrdev(...

	// reserve a page of memory for our hardware /proc/iomem
	if ( check_region(MALab_MM_START,MALab_MM_SIZE) ) {
		printk (KERN_ALERT "LED init_module: memory already in
use\n");
		return -EBUSY;
	}
	request_region(MALab_MM_START,MALab_MM_SIZE,MALab_DEVICE_NAME);

	// enable LocalBus Chip Select CS2 to hit on our address range
	*(volatile u32 *)MPC5xxx_MM_IPBI &= ~0x00040000;
	*(volatile u16 *)(MPC5xxx_MM_CS2_START + 2) = MALab_MM_START >> 16;
	*(volatile u16 *)(MPC5xxx_MM_CS2_STOP + 2) = MALab_MM_END >> 16;
	*(volatile u32 *)MPC5xxx_MM_IPBI |= 0x00040000;

	// map our physical address into kernal virtual address space
	// do I need this call?
	ioaddr = ioremap(MALab_MM_START,MALab_MM_SIZE);

return 0;
}

Later (in a ioctrl routine), I will try and write something to the first
location in my address range.  I tried these three ways:

	*(volatile u16 *)MALab_MM_START = 0x5555;
	outw(0x5555,MALab_MM_START);
	outw(0x5555,ioaddr);

Any and all of the these calls crash the kernel so horrendously I have to
reboot.  Sometimes I have to delete and mknod a new /dev entry.

I have tried the io memory map technique instead of the above io port map
technique, using request_mem_region(), with the same crashing results upon
any writew() call or direct variants.  I tried things without the ioremap()
call--  I get a segmentation fault in these cases.

The request_region() or request_mem_region() seems to work ok.  I can cat
/proc/iomem or /proc/ioports and see my range in there.  I am pretty sure I
am setting up the LocalBus chip select registers ok.

Yet obviously I am doing something profoundly stupid.  Is my error obvious?
Can someone enlighten me in my darkness?

Steven Kaiser
Chemistry Electronics Facility
University of California, Irvine
2347 Natural Sciences 2
Irvine, CA  92697-2025
(949)824-7520

Re: MPC5200b kernel module memory mapping

[sudheer]

Hi Stevenson Kaiser,

Steven Kaiser wrote:
> #define MPC5xxx_MM_IPBI		(MPC5xxx_MBAR + 0x0054)
>
> void *ioaddr = NULL;
>
>
> 	// map our physical address into kernal virtual address space
> 	// do I need this call?
> 	ioaddr = ioremap(MALab_MM_START,MALab_MM_SIZE);
>
>   
Try typecasting.        ioaddr = (u16 *)ioremap (start, size );

Regards
Sudheer

> return 0;
> }
>
> Later (in a ioctrl routine), I will try and write something to the first
> location in my address range.  I tried these three ways:
>
> 	*(volatile u16 *)MALab_MM_START = 0x5555;
> 	outw(0x5555,MALab_MM_START);
> 	outw(0x5555,ioaddr);
>
> Any and all of the these calls crash the kernel so horrendously I have to
> reboot.  Sometimes I have to delete and mknod a new /dev entry.
>
> I have tried the io memory map technique instead of the above io port map
> technique, using request_mem_region(), with the same crashing results upon
> any writew() call or direct variants.  I tried things without the ioremap()
> call--  I get a segmentation fault in these cases.
>
> The request_region() or request_mem_region() seems to work ok.  I can cat
> /proc/iomem or /proc/ioports and see my range in there.  I am pretty sure I
> am setting up the LocalBus chip select registers ok.
>
> Yet obviously I am doing something profoundly stupid.  Is my error obvious?
> Can someone enlighten me in my darkness?
>
> Steven Kaiser
> Chemistry Electronics Facility
> University of California, Irvine
> 2347 Natural Sciences 2
> Irvine, CA  92697-2025
> (949)824-7520
>
>
> _______________________________________________
> Linuxppc-embedded mailing list
> Linuxppc-embedded@ozlabs.org
> https://ozlabs.org/mailman/listinfo/linuxppc-embedded
>
>   

Re: MPC5200b kernel module memory mapping

[Markus Klotzbücher]

Hi Steven,

"Steven Kaiser" <skaiser.uci@gmail.com> writes:

> In a kernel module, I am trying to iomemory map or ioport map a range of
> addresses so later I can talk directly to custom external hardware.  I have
> tried to follow the advice of Rubini chapter 8.  I think I am setting it up
> correctly, but at the precise moment I try to write anything within my
> range, the kernel crashes badly.  My board is a Lite5200b, using a 2.4.25
> kernel.
...
> 	// enable LocalBus Chip Select CS2 to hit on our address range
> 	*(volatile u32 *)MPC5xxx_MM_IPBI &= ~0x00040000;
> 	*(volatile u16 *)(MPC5xxx_MM_CS2_START + 2) = MALab_MM_START >> 16;
> 	*(volatile u16 *)(MPC5xxx_MM_CS2_STOP + 2) = MALab_MM_END >> 16;
> 	*(volatile u32 *)MPC5xxx_MM_IPBI |= 0x00040000;
>
> 	// map our physical address into kernal virtual address space
> 	// do I need this call?
> 	ioaddr = ioremap(MALab_MM_START,MALab_MM_SIZE);

Yes, you do need this call if you want to access physical addresses.

> return 0;
> }
>
> Later (in a ioctrl routine), I will try and write something to the first
> location in my address range.  I tried these three ways:
>
> 	*(volatile u16 *)MALab_MM_START = 0x5555;
> 	outw(0x5555,MALab_MM_START);
> 	outw(0x5555,ioaddr);
>
> Any and all of the these calls crash the kernel so horrendously I have to
> reboot.  Sometimes I have to delete and mknod a new /dev entry.
>
> I have tried the io memory map technique instead of the above io port map
> technique, using request_mem_region(), with the same crashing results upon
> any writew() call or direct variants.  I tried things without the ioremap()
> call--  I get a segmentation fault in these cases.
>
> The request_region() or request_mem_region() seems to work ok.  I can cat
> /proc/iomem or /proc/ioports and see my range in there.  I am pretty

This doesn't really tell you anything, it's mere housekeeping.

> sure I am setting up the LocalBus chip select registers ok.

I would guess this is not the case. What kind of device is this?

Regards

	Markus

RE: MPC5200b kernel module memory mapping

[Steven Kaiser]

Markus:

> > sure I am setting up the LocalBus chip select registers ok.
> 
> I would guess this is not the case. What kind of device is this?

It is a Freescale MPC5200b:
http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=MPC5200B

You are correct.  I was so concerned about the linux driver stuff (
request_region(), ioremap(), etc ), that I was locked into endless studies
on that and see now I clearly overlooked some simple chip setting up.  Doh!
Thanks for reorienting my focus--

int init_module(void) { ...

	// reserve a page of memory for our hardware /proc/iomem
	if ( check_region(MALab_MM_START,MALab_MM_SIZE) ) {
		printk (KERN_ALERT "LED init_module: memory already in
use\n");
		return -EBUSY;
	}
	request_region(MALab_MM_START,MALab_MM_SIZE,LED_DEVICE_NAME);

	// enable LocalBus chip select CS2 to hit on our address range
	*(volatile u32 *)MPC5xxx_MM_IPBI &= ~0x00040000;
	*(volatile u16 *)(MPC5xxx_MM_CS2_START + 2) = MALab_MM_START >> 16;
	*(volatile u16 *)(MPC5xxx_MM_CS2_STOP + 2) = MALab_MM_END >> 16;
	*(volatile u32 *)MPC5xxx_MM_IPBI |= 0x00040000;

	// LocalBus Chip Select 2,3 Configuration Register
	*(volatile u32 *)(MPC5xxx_MBAR + 0x0308) = 0x03031110;
	*(volatile u32 *)(MPC5xxx_MBAR + 0x030c) = 0x03031110;
	// LocalBus Chip Select Control Register
	*(volatile u32 *)(MPC5xxx_MBAR + 0x0318) |= 0x01000000;

	// map our physical address into kernal virtual address space
	ioaddr = ioremap(MALab_MM_START,MALab_MM_SIZE);
	printk(KERN_ALERT "ioaddr: 0x%08x\n", (u32)ioaddr);


and later, any of these calls work:

RE: MPC5200b kernel module memory mapping

[Steven Kaiser]

Markus:

> > sure I am setting up the LocalBus chip select registers ok.
> 
> I would guess this is not the case. What kind of device is this?

You are correct.  I was so concerned about the linux driver stuff (
request_region(), ioremap(), etc ), that I was locked into endless studies
on that and see now I clearly overlooked some simple chip setting up.  Doh!
Thanks for reorienting my focus--

My chip is a Freescale MPC5200b:
http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=MPC5200B

So here's what I've doing that seems to work, as verified by an
oscilloscope:

// 64k I/O Port Space: 0x60000000 - 0x60001000 -> 0x60000000 - 0x60001000 
#define MPC5xxx_MM_CS2_START	(MPC5xxx_MBAR + 0x0014)
#define MPC5xxx_MM_CS2_STOP	(MPC5xxx_MBAR + 0x0018)
#define MPC5xxx_MM_IPBI		(MPC5xxx_MBAR + 0x0054)

#define MALab_MM_START		0x60000000U
#define MALab_MM_END		0x6000ffffU
#define MALab_MM_SIZE		0x00010000U

void *ioaddr = NULL;

int init_module(void) { ...

	// reserve a page of memory for our hardware /proc/iomem
	if ( check_region(MALab_MM_START,MALab_MM_SIZE) ) {
		printk (KERN_ALERT "LED init_module: memory already in
use\n");
		return -EBUSY;
	}
	request_region(MALab_MM_START,MALab_MM_SIZE,LED_DEVICE_NAME);

	// enable LocalBus chip select CS2 to hit on our address range
	*(volatile u32 *)MPC5xxx_MM_IPBI &= ~0x00040000;
	*(volatile u16 *)(MPC5xxx_MM_CS2_START + 2) = MALab_MM_START >> 16;
	*(volatile u16 *)(MPC5xxx_MM_CS2_STOP + 2) = MALab_MM_END >> 16;
	*(volatile u32 *)MPC5xxx_MM_IPBI |= 0x00040000;

	// LocalBus Chip Select 2 Configuration Register
	*(volatile u32 *)(MPC5xxx_MBAR + 0x0308) = 0x03031110;
	// LocalBus Chip Select Control Register
	*(volatile u32 *)(MPC5xxx_MBAR + 0x0318) |= 0x01000000;

	// map our physical address into kernal virtual address space
	ioaddr = ioremap(MALab_MM_START,MALab_MM_SIZE);
	printk(KERN_ALERT "ioaddr: 0x%08x\n", (u32)ioaddr);


then later, any of these calls work (even in interrupt routines it appears):

u32	buf[10];

	*(volatile u16 *)ioaddr = 0x5555;
	outw(0x5555,ioaddr);
	outsw(ioaddr,buf,10);

I guess this is simple stuff for most everybody here.

Steve