Device Tree setup for 8272-based board

[Daniel Ng]

Hi Scott,

On Wed, Jan 21, 2009 at 3:41 AM, Scott Wood <scottwood at freescale.com> wrote:
> On Tue, Jan 20, 2009 at 06:23:08PM +1100, Daniel Ng wrote:
>> PID hash table entries: 128 (order: 7, 512 bytes)
>> time_init: decrementer frequency = 16.500000 MHz
>> time_init: processor frequency   = 330.000000 MHz
>> clocksource: timebase mult[f26c9b2] shift[22] registered
>> clockevent: decrementer mult[439] shift[16] cpu[0]
>> Console: colour dummy ü
>>
>> -at this point the board just reboots.
>
> Looks like something goes wrong when the real serial driver kicks in.

I've managed to enable more debug and see the following boot sequence:

cpm_uart_init_port()
OF: ** translation for device /soc at f0000000/cpm at 119c0/serial at 11a00 **
OF: bus is default (na=1, ns=1) on /soc at f0000000/cpm at 119c0
OF: translating address: 00011a00
OF: parent bus is default (na=1, ns=1) on /soc at f0000000
OF: no ranges, 1:1 translation
OF: parent translation for: 00000000
OF: with offset: 11a00
OF: one level translation: 00011a00
OF: parent bus is default (na=1, ns=1) on /
OF: walking ranges...
OF: default map, cp=0, s=53000, da=11a00
OF: parent translation for: f0000000
OF: with offset: 11a00
OF: one level translation: f0011a00
OF: reached root node
OF: ** translation for device /soc at f0000000/cpm at 119c0/serial at 11a00 **
OF: bus is default (na=1, ns=1) on /soc at f0000000/cpm at 119c0
OF: translating address: 00008000
OF: parent bus is default (na=1, ns=1) on /soc at f0000000
OF: no ranges, 1:1 translation
OF: parent translation for: 00000000
OF: with offset: 8000
OF: one level translation: 00008000
OF: parent bus is default (na=1, ns=1) on /
OF: walking ranges...
OF: default map, cp=0, s=53000, da=8000
OF: parent translation for: f0000000
OF: with offset: 8000
OF: one level translation: f0008000
OF: reached root node
of_irq_map_one: dev=/soc at f0000000/cpm at 119c0/serial at 11a00, index=0
 intsize=2 intlen=2
of_irq_map_raw:
par=/soc at f0000000/interrupt-controller at 10c00,intspec=[0x00000028 0x
00000008...],ointsize=2
of_irq_map_raw: ipar=/soc at f0000000/interrupt-controller at 10c00, size=2
 -> addrsize=1
 -> got it !
irq: irq_create_mapping(0xc02d1320, 0x28)
irq: -> using host @c02d1320
irq: -> obtained virq 40
cpm2_pic_host_map(40, 0x28)
of_get_gpio exited with status -2
of_get_gpio exited with status -2
of_get_gpio exited with status -2
of_get_gpio exited with status -2
of_get_gpio exited with status -2
of_get_gpio exited with status -2
cpm_uart_request_port()
CPM uart[þ

I think the of_get_gpio() error messages are a result of the following
code in cpm_uart_init_port()-

  for (i = 0; i < NUM_GPIOS; i++)
    pinfo->gpios[i] = of_get_gpio(np, i);

-why is this code here? Is it for processing modem control lines? I
know our board doesn't make use of the modem control lines for
ttyCPM0. Therefore, have I misconfigured something in the Device Tree?

Here's the relevant part of the Device Tree-

    cpm at 119c0 {
      #address-cells = <1>;
      #size-cells = <1>;
      #interrupt-cells = <2>;
      compatible = "fsl,mpc8272-cpm", "fsl,cpm2";
      reg = <0x119c0 0x30>;
      ranges;

      muram at 0 {
        #address-cells = <1>;
        #size-cells = <1>;
        ranges = <0x0 0x0 0x10000>;

        data at 0 {
          compatible = "fsl,cpm-muram-data";
          reg = <0x0 0x2000 0x9800 0x800>;
        };
      };

      brg at 119f0 {
        compatible = "fsl,mpc8272-brg",
                     "fsl,cpm2-brg",
                     "fsl,cpm-brg";
        reg = <0x119f0 0x10 0x115f0 0x10>;
      };

      serial at 11a00 {
        device_type = "serial";
        compatible = "fsl,mpc8272-scc-uart",
                     "fsl,cpm2-scc-uart";
        reg = <0x11a00 0x20 0x8000 0x100>;
        interrupts = <40 8>;
        interrupt-parent = <&PIC>;
        fsl,cpm-brg = <1>;
        fsl,cpm-command = <0x800000>;
      };

  };

    PIC: interrupt-controller at 10c00 {
      #interrupt-cells = <2>;
      interrupt-controller;
      reg = <0x10c00 0x80>;
      compatible = "fsl,mpc8272-pic", "fsl,cpm2-pic";
    };


Would you please explain what the following lines mean, so I can use
some more appropriate values for my particular board?-

1) In the serial at 11a00 node-

a) reg = <0x11a00 0x20 0x8000 0x100>;
b) interrupts = <40 8>;
c) fsl,cpm-brg = <1>;
d) fsl,cpm-command = <0x800000>;


2) In the brg at 119f0 node-
reg = <0x119f0 0x10 0x115f0 0x10>;


3) In the PIC: interrupt-controller at 10c00 node-
reg = <0x10c00 0x80>;


I have read the relevant documentation under Documentation/powerpc and
Documentation/powerpc/dts-bindings, but these do not seem to go into
enough detail eg.
Documentation/powerpc/dts-bindings/fsl/cpm_qe/cpm/brg.txt says the
following about the reg property-

- reg : There may be an arbitrary number of reg resources; BRG
  numbers are assigned to these in order.

-> does this mean that each number represents a BRG register? So there
can be a maximum of 1+8=9 reg values, since there are 8 BRG registers?

As for Documentation/powerpc/dts-bindings/fsl/cpm_qe/serial.txt, there
is no explanation at all for what the 'reg', 'interrupts', 'brg' and
'command' values mean... Am I missing something obvious?

Similarly for Documentation/powerpc/dts-bindings/fsl/cpm_qe/pic.txt,
there is no explanation of the 'reg' value. Also, it mentions a
'second interrupt cell' but I only see one in the example it gives.
Here is what it says-

* Interrupt Controllers

Currently defined compatibles:
- fsl,cpm1-pic
  - only one interrupt cell
- fsl,pq1-pic
- fsl,cpm2-pic
  - second interrupt cell is level/sense:
    - 2 is falling edge
    - 8 is active low

Example:
  interrupt-controller at 10c00 {
    #interrupt-cells = <2>;
    interrupt-controller;
    reg = <10c00 80>;
    compatible = "mpc8272-pic", "fsl,cpm2-pic";
  };


Does the level/sense refer to ALL interrupts?

Cheers,
Daniel