[Qemu-devel] Re: [PATCH V5 19/29] pci: split out ioport address parsing from pci configuration access logic.

["Michael S. Tsirkin" <mst@redhat.com>]

On Fri, Oct 09, 2009 at 03:28:52PM +0900, Isaku Yamahata wrote:
> Split out pci_data_{write, read} into two part, one is the code which
> convert ioport address into pci device and the other is the code
> which access PCI configuration space.
> 
> Later PCI express code will use the access code.
> PCI express addressing scheme is different so that the address
> must be parsed differently.
> 
> PCI:
>  0- 7 bit: offset in the configuration space (256bytes)
>  7-15 bit: devfn
> 16-24 bit: bus
> 
> PCI express:
>  0-11 bit: offset in the configuration space (4KBytes)
> 12-19 bit: devfn
> 20-28 bit: bus
> 
> Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>

So I think I said this already: the only useful thing that
pci_data_read/write does is address conversion which is different for
express.  PCI Express should do its own thing and then call
pci_dev->config_read / pci_dev->config_write directly.

I think this will even make it possible to put express code in a
separate file from pci.c.

> ---
>  hw/pci.c |   80 ++++++++++++++++++++++++++++++-------------------------------
>  1 files changed, 39 insertions(+), 41 deletions(-)
> 
> diff --git a/hw/pci.c b/hw/pci.c
> index 0021c96..d472b58 100644
> --- a/hw/pci.c
> +++ b/hw/pci.c
> @@ -654,46 +654,24 @@ void pci_default_write_config(PCIDevice *d, uint32_t addr, uint32_t val, int l)
>          pci_update_mappings(d);
>  }
>  
> -static inline PCIDevice *pci_addr_to_dev(PCIBus *bus, uint32_t addr)
> -{
> -    uint8_t bus_num = (addr >> 16) & 0xff;
> -    uint8_t devfn = (addr >> 8) & 0xff;
> -    return pci_find_device(bus, bus_num, PCI_SLOT(devfn), PCI_FUNC(devfn));
> -}
> -
> -static inline int pci_addr_to_config(uint32_t addr)
> -{
> -    return addr & 0xff;
> -}
> -
> -void pci_data_write(void *opaque, uint32_t addr, uint32_t val, int len)
> +static void pci_dev_write_config(PCIDevice *pci_dev,
> +                                 uint32_t config_addr, uint32_t val, int len)
>  {
> -    PCIBus *s = opaque;
> -    PCIDevice *pci_dev;
> -    int config_addr;
> -
> -#if 0
> -    PCI_DPRINTF("pci_data_write: addr=%08x val=%08x len=%d\n",
> -                addr, val, len);
> -#endif
> -    pci_dev = pci_addr_to_dev(s, addr);
> +    assert(len == 1 || len == 2 || len == 4);
>      if (!pci_dev)
>          return;
> -    config_addr = addr & 0xff;
> -    config_addr = pci_addr_to_config(addr);
> -    PCI_DPRINTF("pci_config_write: %s: addr=%02x val=%08x len=%d\n",
> -                pci_dev->name, config_addr, val, len);
> +
> +    PCI_DPRINTF("%s: %s: addr=%02"PRIx32" val=%08"PRI32x" len=%d\n",
> +                __func__, pci_dev->name, config_addr, val, len);
>      pci_dev->config_write(pci_dev, config_addr, val, len);
>  }
>  
> -uint32_t pci_data_read(void *opaque, uint32_t addr, int len)
> +static uint32_t pci_dev_read_config(PCIDevice *pci_dev,
> +                                    uint32_t config_addr, int len)
>  {
> -    PCIBus *s = opaque;
> -    PCIDevice *pci_dev;
> -    int config_addr;
>      uint32_t val;
>  
> -    pci_dev = pci_addr_to_dev(s, addr);
> +    assert(len == 1 || len == 2 || len == 4);
>      if (!pci_dev) {
>          switch(len) {
>          case 1:
> @@ -707,20 +685,40 @@ uint32_t pci_data_read(void *opaque, uint32_t addr, int len)
>              val = 0xffffffff;
>              break;
>          }
> -        goto the_end;
> +    } else {
> +        val = pci_dev->config_read(pci_dev, config_addr, len);
> +        PCI_DPRINTF("%s: %s: addr=%02"PRIx32" val=%08"PRIx32" len=%d\n",
> +                    __func__, pci_dev->name, config_addr, val, len);
>      }
> -    config_addr = pci_addr_to_config(addr);
> -    val = pci_dev->config_read(pci_dev, config_addr, len);
> -    PCI_DPRINTF("pci_config_read: %s: addr=%02x val=%08x len=%d\n",
> -                pci_dev->name, config_addr, val, len);
> - the_end:
> -#if 0
> -    PCI_DPRINTF("pci_data_read: addr=%08x val=%08x len=%d\n",
> -                addr, val, len);
> -#endif
>      return val;
>  }
>  
> +static inline PCIDevice *pci_addr_to_dev(PCIBus *bus, uint32_t addr)
> +{
> +    uint8_t bus_num = (addr >> 16) & 0xff;
> +    uint8_t devfn = (addr >> 8) & 0xff;
> +    return pci_find_device(bus, bus_num, PCI_SLOT(devfn), PCI_FUNC(devfn));
> +}
> +
> +static inline int pci_addr_to_config(uint32_t addr)
> +{
> +    return addr & 0xff;
> +}
> +
> +void pci_data_write(void *opaque, uint32_t addr, uint32_t val, int len)
> +{
> +    PCIBus *s = opaque;
> +    pci_dev_write_config(pci_addr_to_dev(s, addr), pci_addr_to_config(addr),
> +                         val, len);
> +}
> +
> +uint32_t pci_data_read(void *opaque, uint32_t addr, int len)
> +{
> +    PCIBus *s = opaque;
> +    return pci_dev_read_config(pci_addr_to_dev(s, addr),
> +                               pci_addr_to_config(addr), len);
> +}
> +
>  /***********************************************************/
>  /* generic PCI irq support */
>  
> -- 
> 1.6.0.2