[ECOS] Performing a soft reset on the Cirrus Logic EP7312

[Dan Conti]

You should be able to do the following:

{
  void (*f)() = 0;
  f();
}

since you have already disabled the cache and turned off interrupts, you
should be fine. you might want to make sure that you call
HAL_UCACHE_INVALIDATE() _after_ calling HAL_UCACHE_DISABLE().

in the event that the above call to f() doesn't work, you could try
using:

  void (*f)() = hal_vsr_table[0];

which (should) give you the appropriate reset vector.

> -----Original Message-----
> From: Chris Sekula [mailto:chriss@turnpikeglobal.com]
> Sent: Tuesday, January 29, 2002 12:17 PM
> To: ecos-discuss@sources.redhat.com
> Subject: [ECOS] Performing a soft reset on the Cirrus Logic EP7312
> 
> 
> I'm programming an application for the Cirrus Logic EP7312 with eCos
> 1.3.1.  I'd like to provide the ability to reprogram the
> kernel/application residing in Flash by uploading a new 
> application via
> the serial port or a wireless module. Once the reprogramming is
> complete, I want the application to reset itself and begin 
> executing on
> its own without the need for a power on reset.
>  
> I wrote the code to accept a new kernel/application from the 
> serial port
> or wireless module, but it appears that I am having problems executing
> the reset command. 
>  
> My code accepts each byte of the new application from either 
> the serial
> port or wireless module and then copies each byte to a 
> defined location
> in RAM. I then copy the code for erasing sectors of the Flash and
> writing to the Flash into RAM as well. I then disable the cache, lock
> the scheduler and disable interrupts. I then execute the function for
> erasing and programming which had been copied into RAM. After
> programming the final command that I execute out of RAM is my reset
> command which is an assembly command that loads the program 
> counter with
> the address of the reset vector:
>  
> asm volatile ("ldr pc, =0xe0000000");
>  
> where 0xe0000000 is, I presume, the reset vector for the 
> EP7312 on eCos
> 1.3.1.
>  
> Initially, I found that this procedure worked quite well. The
> application would accept the new code from the serial port, reprogram
> itself, perform the reset and start up again. However, recently I have
> been noticing that the application has been hanging after 
> reprogramming.
> I've checked the Flash with a debugger to verify that the
> kernel/application had been reprogrammed correctly. It appears that my
> reset command may be incorrect.
>  
> I performed an additional test to exercise the reset command. The
> following code should toggle an LED on and off 5 times and then issue
> the reset command. To check if the reset command executes, I issue a
> command following the reset to turn on a Flasher. If the reset command
> does not execute, I should see the Flasher begin blinking 
> following the
> 5 toggles of the LED.
>  
> #define STACKSIZE 5000
> static char stack[STACKSIZE];
> static cyg_handle_t hmainThread;
> static cyg_thread mainThread_obj;
> static void MainProc(CYG_ADDRESS data);
> 
> extern "C" void cyg_user_start(void)
> {
>  cyg_thread_create(4, MainProc, (cyg_addrword_t)0, "mainproc",
>        (void*)&stack, STACKSIZE, &hmainThread, 
>        &mainThread_obj);
>  cyg_thread_resume(hmainThread);
> }
> 
> static void MainProc(CYG_ADDRESS data)
> {
>  HAL_IO_REGISTER PortDOut = 0x80000003;
>  HAL_IO_REGISTER Flasher = 0x800022c0;
>  for (int x=0; x<5; x++)
>  {
>   HAL_WRITE_UINT8(PortDOut, 0x06); // LED ON
>   cyg_thread_delay(50);
>   HAL_WRITE_UINT8(PortDOut, 0x04); //  LED OFF
>   cyg_thread_delay(50);
>  }
> 
>  asm volatile ("ldr pc, =0xe0000000");
> 
> // flash every 1 sec, 50% duty cycle (eg. .5 secs on, .5 secs off)
>  HAL_WRITE_UINT8(Flasher, 0x60); 
>  
> }
>  
> The first LED toggled 5 times and then remained off. The 
> Flasher did not
> begin blinking. This indicates to me that the reset command executes,
> but the kernel hangs somewhere after restarting.
>  
> Can anyone offer any suggestions as to how to perform a 
> 'software reset'
> correctly or how to possibly correct what I am already doing? 
>  
> Any comments would be greatly appreciated.
>  
> Regards,
>  
> CHRIS.
>  
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