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Can't change pin mux in Linux

Eric Williams
Prodigy 180 points

I have a DM8148 running 2.6.37 Linux kernel.

I am trying to change pinmuxing from userspace program ran with root access.

I am able to read the pinmuxing but I can not write.  Nothing errors out, it just doesn't change the value when I read it back.

 My code is below, please help.

target = 0x48140B10; //Touch_int
target2 = 0x48140AF0; //Touch_rst
value = 0x00050080;
/* Map one page */
map_base = mmap(0, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, target & ~MAP_MASK);
if(map_base == (void *) -1) {
printf("Memory map failed.\n");
} else {
printf("Memory mapped at address %p.\n", map_base);
}
fflush(stdout);


virt_addr = map_base + target - (target & ~MAP_MASK);
virt_addr2 = map_base + target2 - (target2 & ~MAP_MASK);
/* acess remapped region here */
int read_result, read_result2, new_result, new_result2;
read_result = *((volatile unsigned long *) virt_addr);
read_result2 = *((volatile unsigned long *) virt_addr);

*((volatile unsigned long *) virt_addr) = value;
*((volatile unsigned long *) virt_addr2) = value;

msync(map_base, MAP_SIZE, MS_SYNC);
new_result = *((volatile unsigned long *) virt_addr);
new_result2 = *((volatile unsigned long *) virt_addr);

printf(" Was %08x , %08x\n", read_result, read_result2 );
printf(" Set to %08x , %08x\n", value, value);
printf("Now %08x, %08x\n", new_result, new_result2);

  • 0
    TI__Guru 59700 points

    I believe  this behaviour is expected. PINMUX register write are protected by MMR_LOCK which can be unlocked only when processor is in supervisor mode. I think you would have to write a kernel driver if you want to change pinmux settings or do the change in uboot.

     

  • 0 in reply to Badri Narayanan
    Prodigy 180 points

    Ok thanks for response...I'll try to do it in driver and let you know what happens.

  • 0 in reply to Eric Williams
    Prodigy 180 points

    Yes, I was able to change pinmuxing from driver.

    Thanks.

  • 0 in reply to Badri Narayanan
    Prodigy 180 points

    Badri can you provide assistance with my post here:

    http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/t/226070.aspx

  • 0 in reply to Badri Narayanan
    TI__Genius 13460 points

    Hi Badri,

    My customer find that they can't modify PINMUX reg under linux user mode, while it works under kernel mode.

    Is the ARM supervisor correspond to the linux kernel mode ? It looks like the MMR_lock reg actually an ARM register ?

    Is it possible to set kind of register to pull ARM into supervisor mode to simplify the SW development other than kernel driver?

    BR

    Eason

  • 0 in reply to Eason Wang
    TI__Guru 59700 points

    DVR RDK 4.0 includes a /dvr_rdk/bin/ti816x/kermod/prot_reg_rdwr.ko kernel module which can be used to read and modify protected mode registers. You can insmod this driver and use it

  • 0 in reply to Badri Narayanan
    Guru 20755 points

    Hi Badri,

    I am trying to change sata pll registers value using devmem2 and later mem_rdwr

    These utilities don't output failure message on writing, but when reading the same register I see that the value did not change. Is it from the same reason above ?

    Is there a way to use prot_reg_rdwr.ko from console ?

    root@dm814x:/opt/dvr_rdk/ti814x/bin# ./mem_rdwr.out --wr 48140720 12345678

    ORG 0x48140720: 40007077
    NEW 0x48140720: 40007077

    root@dm814x:~# devmem2 0x48140720 w 0xc0007077
    /dev/mem opened.
    Memory mapped at address 0x4005c000.
    Read at address 0x48140720 (0x4005c720): 0x40007077
    Write at address 0x48140720 (0x4005c720): 0xC0007077, readback 0xC0007077
    root@dm814x:~# devmem2 0x48140720
    /dev/mem opened.
    Memory mapped at address 0x40252000.
    Read at address 0x48140720 (0x40252720): 0x40007077

    Thanks,

    Ran

  • 0 in reply to ranchu
    TI__Guru 59700 points

    The proto_reg_rdwr.ko is meant ot be used from console. Usage is documented in the readme.txt present in

    /dvr_rdk/mcfw/src_linux/utils/prot_reg_rdwr/README.txt

    Reproduced below

    * Make sure DebugFS is mounted. If not follow steps below to mount it.

  mount -t debugfs null /sys/kernel/debug

* Do "insmod prot_reg_rdwr.ko" to insert the .ko. This is NOT done by default in DVRRDK

* Now you should see the prot_reg_debug entry in the following location

  /sys/kernel/debug/prot_reg/mem

* To write to system space

  echo "w <start_address> <data> <count>" > /sys/kernel/debug/prot_reg/mem

  start_address : From where to start writing (in hex format i.e. 0xAA55AA55)
  data		: 32-bit data to be written (in hex format i.e. 0xAA55AA55)
  count		: Number of location to repeat the data (in decimal format)

  example
  -------
  1. echo "w 0x48140b34 0x2 1" > /sys/kernel/debug/prot_reg/mem

	This would write 0x2 to one location starting from 0x48140b34

  2. echo "w 0x48140b34 0x2 10" > /sys/kernel/debug/prot_reg/mem

	This would write 0x2 to ten locations starting from 0x48140b34.
	So locations 0x48140b34 through 0x48140b58 would have 0x2

* To read from system space

  echo "r <start_address> <count>" > /sys/kernel/debug/prot_reg/mem

  Start printing the contents starting from <start_address> and end after
  <count> times.

 example
 -------
 1. echo "r 0x48140b34 1" > /sys/kernel/debug/prot_reg/mem

	Print the contents of location 0x48140b34

 2. echo "r 0x48140b34 10" > /sys/kernel/debug/prot_reg/mem

	Print contents of 10 location starting from 0x48140b34.
	So locations 0x48140b34 through 0x48140b58 will be printed.