Can't seem to hook up omap3 uarts

[Peter Chubb]

I've tried:

qemu-system-arm-M beagle \
        -chardev socket,ipv4,host=localhost,port=4444,server,id=sock3 \
        -chardev socket,ipv4,host=localhost,port=4445,server,nowait,id=sock2 \
         -device omap_uart,chardev=sock3,id=uart3 \
         -device omap_uart,chardev=sock2,id=uart2 \
         -nographic \
         -mtdblock images/wombat-image-arm-omap3-nand

but uart3 ends up connected to stdio, and uart2 to nothing at all.

info qtree shows more than one uart3:

(qemu) info qtree
bus: main-system-bus
  type System
  dev: omap_uart, id "uart2"
    dev-prop: chardev = sock2
    irq 3
    mmio ffffffff/00000400
  dev: omap_uart, id "uart3"
    dev-prop: chardev = sock3
    irq 3
    mmio ffffffff/00000400

 ...
  dev: omap_uart, id "uart3"
    dev-prop: chardev = serial0
    irq 3
    mmio 49020000/00001000
  dev: omap_uart, id "uart2"
    dev-prop: chardev = uart2
    irq 3
    mmio 4806c000/00001000
  dev: omap_uart, id "uart1"
    dev-prop: chardev = uart1
    irq 3
    mmio 4806a000/00001000
  dev: omap2-intc, id ""
    gpio-in 96
    irq 2
    mmio 48200000/00001000

[Peter Maydell (pmaydell)]

You can't use '-device' to try to change the properties for an existing device on the board. '-device' always creates a new device, so it only really makes sense for pluggable buses like USB/PCI. You might try playing with the '-global' option which lets you set properties on existing devices.

[Peter Chubb (peter-chubb-1)]

>>>>> "Peter" == Peter Maydell <email address hidden> writes:

Peter> You can't use '-device' to try to change the properties for an
Peter> existing device on the board. '-device' always creates a new
Peter> device, so it only really makes sense for pluggable buses like
Peter> USB/PCI. You might try playing with the '-global' option which
Peter> lets you set properties on existing devices.

Hmmm. According to docs/qdev-device-use.txt the old, relatively
simple,

   -serial tcp:127.0.0.1:4444,server

(which works for uart3, but not for any of the other uarts) should be
replaced with the more clumsy-to-type:

  -chardev socket,host=127.0.0.1,port=4444,server,id=sock3
  -device omap_uart,id=uart3,chardev=sock3

If this is wrong, then it should be updated.

I can't see how to use -global to achieve this. It adds global
properties, not per-instance properties.

So for instance
  qemu-system -arm -M beagle -nographic \
      -chardev socket,host=127.0.0.1,port=4444,server,id=sock3 \
      -global uart3.chardev=sock3 \
      -mtdblock images/wombat-image-arm-omap3-nand

still leaves uart3 hooked up to stdio.

You could patch beagle.c which would at least enable multiple -serial
options.

diff --git a/hw/beagle.c b/hw/beagle.c
index 01d665a..b0d2cd6 100644
--- a/hw/beagle.c
+++ b/hw/beagle.c
@@ -71,7 +71,7 @@ static void beagle_common_init(ram_addr_t ram_size,
 #error MAX_SERIAL_PORTS must be at least 1!
 #endif
     s->cpu = omap3_mpu_init(sysmem, cpu_model, ram_size,
- NULL, NULL, serial_hds[0], NULL);
+ serial_hds[2], serial_hds[1], serial_hds[0], NULL);

     s->nand = nand_init(dmtd ? dmtd->bdrv : NULL, NAND_MFR_MICRON, 0xba);
     nand_setpins(s->nand, 0, 0, 0, 1, 0); /* no write-protect */

[Peter Maydell (pmaydell)]

On 18 May 2012 00:58, Peter Chubb <email address hidden> wrote:
>>>>>> "Peter" == Peter Maydell <email address hidden> writes:
>
> Peter> You can't use '-device' to try to change the properties for an
> Peter> existing device on the board. '-device' always creates a new
> Peter> device, so it only really makes sense for pluggable buses like
> Peter> USB/PCI. You might try playing with the '-global' option which
> Peter> lets you set properties on existing devices.
>
> Hmmm.  According to docs/qdev-device-use.txt the old, relatively
> simple,
>
>   -serial tcp:127.0.0.1:4444,server
>
> (which works for uart3, but not for any of the other uarts) should be
> replaced with the more clumsy-to-type:
>
>  -chardev socket,host=127.0.0.1,port=4444,server,id=sock3
>  -device omap_uart,id=uart3,chardev=sock3
>
> If this is wrong, then it should be updated.

The qdev documentation tends to assume pluggable devices,
like isa-serial. Trying to fiddle with the builtin devices
is not so well tested and documented, I'm afraid.

> I can't see how to use -global to achieve this.  It adds global
> properties, not per-instance properties.

In that case I'm out of ideas; I suggest you find an equivalent
case that uses one of the standard models in qemu upstream as
an example, and ask on qemu-devel...

> You could patch beagle.c which would at least enable multiple -serial
> options.
>
> diff --git a/hw/beagle.c b/hw/beagle.c
> index 01d665a..b0d2cd6 100644
> --- a/hw/beagle.c
> +++ b/hw/beagle.c
> @@ -71,7 +71,7 @@ static void beagle_common_init(ram_addr_t ram_size,
>  #error MAX_SERIAL_PORTS must be at least 1!
>  #endif
>     s->cpu = omap3_mpu_init(sysmem, cpu_model, ram_size,
> -                            NULL, NULL, serial_hds[0], NULL);
> +                            serial_hds[2], serial_hds[1], serial_hds[0], NULL);
>
>     s->nand = nand_init(dmtd ? dmtd->bdrv : NULL, NAND_MFR_MICRON, 0xba);
>     nand_setpins(s->nand, 0, 0, 0, 1, 0); /* no write-protect */

Does a beagle actually physically have more than one serial port?