Re: [Qemu-devel] Ping [PATCH 0/2] Add TPCI200 and IP-Octal 232 IndustryPack emulation

[Alberto Garcia]

On Sun, Oct 07, 2012 at 12:13:53PM +0200, Avi Kivity wrote:

> Luckily the low-order bits are used for offsets, and the high-order
> bits are used for selecting the sub-device.
> 
> So you could easily have
> 
>  struct IPackDevice {
>      DeviceState qdev;
>      int32_t slot;
>      /* IRQ objects for the IndustryPack INT0# and INT1# */
>      qemu_irq *irq;
>      MemoryRegion io_space;
>      MemoryRegion id_space;
>      MemoryRegion int_space;
>      MemoryRegion mem8_space;  /* for las3 */
>      MemoryRegion mem16_space; /* for las2 */
>  };
> 
> The PCI device would then just map each space (with
> memory_region_add_subregion()) into las1/las2/las3 such that the
> high bits select the device/space.  The low bits would automatically
> become the offset into the space.

Hey, I finally found some time to look into this, the problem that I
see is that the PCI carrier doesn't just map each space into its local
address spaces, in addition to that:

  1) it changes the data and addresses according to the endianness
     configuration in the local configuration registers (PCI BAR0).
     See adjust_addr()/adjust_value() and page 20 of the user manual.

     http://www.tews.com/Products/ArticleGroup/TPCI/TPCI200.html

  2) read accesses to the local address space 1 are also used to
     acknowledge interrupts (manual page 33 and tpci200_read_las1()).



On a related note, I was wondering whether it would be simpler to get
rid of tpci200_cfg_ops and replace the current implementation of the
local configuration registers with something like this:

memory_region_init_ram_ptr(&s->mmio, "tpci200_mmio", 128, s->local_cfg);
memory_region_init_alias(&s->io, "tpci200_io", &s->mmio, 0, 128);
pci_register_bar(&s->dev, 0, PCI_BASE_ADDRESS_SPACE_MEMORY, &s->mmio);
pci_register_bar(&s->dev, 1, PCI_BASE_ADDRESS_SPACE_IO,     &s->io);

(s->local_cfg would contain the config registers data)

But it doesn't seem to work.

Berto