[Qemu-devel] Re: [PATCH V6 20/32] pci: factor out the conversion logic from io port address into pci device.

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

On Fri, Oct 30, 2009 at 09:21:14PM +0900, Isaku Yamahata wrote:
> factor out the logic which converts io port address into pci device
> and offset in PCI configuration space.
> 
> Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
> ---
>  hw/pci.c |   32 ++++++++++++++++++--------------
>  1 files changed, 18 insertions(+), 14 deletions(-)
> 
> diff --git a/hw/pci.c b/hw/pci.c
> index 3e5780a..d0a96c6 100644
> --- a/hw/pci.c
> +++ b/hw/pci.c
> @@ -663,24 +663,33 @@ 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;

& 0xff is not necessary here, is it?

> +    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 & (PCI_CONFIG_SPACE_SIZE - 1);
> +}
> +

This one is more clear opencoded, IMO.
It also seems that the fact that it is 0xff == PCI_CONFIG_SPACE_SIZE - 1 here is
just a coinsidence: it depends on pci host. Right?
Maybe 0xff is more appropriate here.

>  void pci_data_write(void *opaque, uint32_t addr, uint32_t val, int len)
>  {
>      PCIBus *s = opaque;
>      PCIDevice *pci_dev;
> -    int config_addr, bus_num;
> +    int config_addr;
>  
>  #if 0
>      PCI_DPRINTF("pci_data_write: addr=%08x val=%08x len=%d\n",
>                  addr, val, len);
>  #endif
> -    bus_num = (addr >> 16) & 0xff;
> -    s = pci_find_bus(s, bus_num);
> -    if (!s)
> -        return;
> -    pci_dev = s->devices[(addr >> 8) & 0xff];
> +    pci_dev = pci_addr_to_dev(s, addr);
>      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_dev->config_write(pci_dev, config_addr, val, len);
> @@ -690,16 +699,11 @@ uint32_t pci_data_read(void *opaque, uint32_t addr, int len)
>  {
>      PCIBus *s = opaque;
>      PCIDevice *pci_dev;
> -    int config_addr, bus_num;
> +    int config_addr;
>      uint32_t val;
>  
> -    bus_num = (addr >> 16) & 0xff;
> -    s = pci_find_bus(s, bus_num);
> -    if (!s)
> -        goto fail;
> -    pci_dev = s->devices[(addr >> 8) & 0xff];
> +    pci_dev = pci_addr_to_dev(s, addr);
>      if (!pci_dev) {
> -    fail:
>          switch(len) {
>          case 1:
>              val = 0xff;
> @@ -714,7 +718,7 @@ uint32_t pci_data_read(void *opaque, uint32_t addr, int len)
>          }
>          goto the_end;
>      }
> -    config_addr = addr & 0xff;
> +    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);
> -- 
> 1.6.0.2
> 
>