Dealing with DSP Tasks from the kernel space

Dealing with DSP Tasks from the kernel space

[Eduardo Bezerra]

Hi all,


  I'm tring to load a DSP task from the kernel space. I know that this
stuff is done by a user space utility, dspctl ou dsp_dld. However, I
want to know how to deal (load, communicate, unload, etc) with DSP tasks
from the Kernel Space. There is no much documentation about the code
found in arch/arm/plat-omap/dsp/*. Documentation about DSP Gateway
project comments more user space and "dsp space" related issues.

  Nevertheless, I know that DSP code only exports its symbols if
it is built as a module. When this is done, I can access some importants
objects, such as:

extern unsigned long dspmem_base, dspmem_size,
                     daram_base, daram_size,
                     saram_base, saram_size;
extern struct clk *api_ck_handle;
extern int exmap_valid(void *vadr, size_t len);

  and tranlate dsp adress space into virtual address space with:

#define dspword_to_virt(dw)     ((void *)(dspmem_base + ((dw) << 1)))

  with this, I can write in the dsp memory space by simple:

  if (omap_dsp_request_mem() < 0)
        return -EBUSY;
  clk_use(api_ck_handle);

  memcpy(vadr, buf, written);

  omap_dsp_release_mem();
  clk_unuse(api_ck_handle);

  and, validate any tlb entry with: exmap_valid(vadr, len), if I need
to write in the any shared space.

  I would like to know if the above information is correct and what is
wrong with the steps bellow to load a DSP task:

/*
 * I need to export some symbols from the dsp code to call them here.
 */
        int ret = 0;
        long rstvct;

        mpui_byteswap_off();

        /* Do the loading here writing the section using the procedure
           described above */
        rstvct = load_dsptask(dspbinary, BINARY_SIZE);

        if (rstvct > 0x00ffffff) {
                printk("Can't determine reset vector "
                                "address: %lx\n", rstvct);
                goto out;
        }

        dsp_cpustat_request(CPUSTAT_RESET);

        ret = dsp_set_rstvect(rstvct);
        if (ret < 0)
                goto out;

        dsp_cpustat_request(DSP_RUN);
        ret = dspcfg();

   because it hangs up when it "runs" the dsp cpu (dsp_cpustat_request).
It falls into a TLB miss.
   If someone knows where I can find documentation to do this stuff (or
even deal with the DSP into kernel space) I'd appreciate.

BR,


Eduardo Bezerra Valentin

Re: Dealing with DSP Tasks from the kernel space

[toshihiro.kobayashi]

HI,

From: Eduardo Bezerra <edubezval@gmail.com>
Subject: Dealing with DSP Tasks from the kernel space
Date: Wed, 11 Jan 2006 11:22:51 -0400

>   I'm tring to load a DSP task from the kernel space. I know that this
> stuff is done by a user space utility, dspctl ou dsp_dld. However, I
> want to know how to deal (load, communicate, unload, etc) with DSP tasks
> from the Kernel Space. There is no much documentation about the code
> found in arch/arm/plat-omap/dsp/*. Documentation about DSP Gateway
> project comments more user space and "dsp space" related issues.
>
>   Nevertheless, I know that DSP code only exports its symbols if
> it is built as a module. When this is done, I can access some importants
> objects, such as:
> 
> extern unsigned long dspmem_base, dspmem_size,
>                      daram_base, daram_size,
>                      saram_base, saram_size;
> extern struct clk *api_ck_handle;
> extern int exmap_valid(void *vadr, size_t len);
> 
>   and tranlate dsp adress space into virtual address space with:
> 
> #define dspword_to_virt(dw)     ((void *)(dspmem_base + ((dw) << 1)))
> 
>   with this, I can write in the dsp memory space by simple:
> 
>   if (omap_dsp_request_mem() < 0)
>         return -EBUSY;
>   clk_use(api_ck_handle);
> 
>   memcpy(vadr, buf, written);
> 
>   omap_dsp_release_mem();
>   clk_unuse(api_ck_handle);
> 
>   and, validate any tlb entry with: exmap_valid(vadr, len), if I need
> to write in the any shared space.
> 
>   I would like to know if the above information is correct and what is
> wrong with the steps bellow to load a DSP task:

Yes, they seems to be correct as the same is done in intmem_write() or
exmem_write().

> /*
>  * I need to export some symbols from the dsp code to call them here.
>  */
>         int ret = 0;
>         long rstvct;
> 
>         mpui_byteswap_off();
> 
>         /* Do the loading here writing the section using the procedure
>            described above */
>         rstvct = load_dsptask(dspbinary, BINARY_SIZE);
> 
>         if (rstvct > 0x00ffffff) {
>                 printk("Can't determine reset vector "
>                                 "address: %lx\n", rstvct);
>                 goto out;
>         }
> 
>         dsp_cpustat_request(CPUSTAT_RESET);
> 
>         ret = dsp_set_rstvect(rstvct);
>         if (ret < 0)
>                 goto out;
> 
>         dsp_cpustat_request(DSP_RUN);
>         ret = dspcfg();
> 
>    because it hangs up when it "runs" the dsp cpu (dsp_cpustat_request).
> It falls into a TLB miss.

What DSP binary do you use? Is it known to work fine, at least runs without
MMU fault?

I'd propose you how to check if your loader is working correctly or not:
Once you load the DSP binary with my dspctl, and dump the DSP memory.
(for example using dd for /dev/dspctl/mem)
Then do the same with your kernel binary loader, and you can compare the
two results.

Also the simple_load_code() in dsp_common.c would be the good reference
for you, that loads a tiny code into the DSP spce within the kernel.
It contains byte swapping operation.

>    If someone knows where I can find documentation to do this stuff (or
> even deal with the DSP into kernel space) I'd appreciate.

Unfortunately ther's no such a documentation.
I'd appreciate if you could contribute on it, when you could complete it. :)

BR,
Toshihiro Kobayashi