[SeaBIOS] [RFC PATCH v2 4/6] hw/pci: introduce bridge-only vendor-specific capability to provide some hints to firmware

[Alexander Bezzubikov]

2017-07-23 18:57 GMT+03:00 Marcel Apfelbaum <marcel at redhat.com>:

> On 23/07/2017 1:15, Aleksandr Bezzubikov wrote:
>
>> On PCI init PCI bridges may need some
>> extra info about bus number to reserve, IO, memory and
>> prefetchable memory limits. QEMU can provide this
>> with special vendor-specific PCI capability.
>>
>> Sizes of limits match ones from
>> PCI Type 1 Configuration Space Header,
>> number of buses to reserve occupies only 1 byte
>> since it is the size of Subordinate Bus Number register.
>>
>>
> Hi Alexandr,
>
> Signed-off-by: Aleksandr Bezzubikov <zuban32s at gmail.com>
>> ---
>>   hw/pci/pci_bridge.c         | 27 +++++++++++++++++++++++++++
>>   include/hw/pci/pci_bridge.h | 18 ++++++++++++++++++
>>   2 files changed, 45 insertions(+)
>>
>> diff --git a/hw/pci/pci_bridge.c b/hw/pci/pci_bridge.c
>> index 720119b..8ec6c2c 100644
>> --- a/hw/pci/pci_bridge.c
>> +++ b/hw/pci/pci_bridge.c
>> @@ -408,6 +408,33 @@ void pci_bridge_map_irq(PCIBridge *br, const char*
>> bus_name,
>>       br->bus_name = bus_name;
>>   }
>>   +
>> +int pci_bridge_help_cap_init(PCIDevice *dev, int cap_offset,
>>
>
> Can you please rename to something like
> 'pci_bridge_qemu_cap_init' to be more specific?
>
> +                              uint8_t bus_reserve, uint32_t io_limit,
>> +                              uint16_t mem_limit, uint64_t pref_limit,
>>
>
>
> I am not sure regarding "limit" suffix, this
> is a reservation, not a limitation.


I'd like this fields names to match actual registers which
are going to get the values.


>
>
> +                              Error **errp)
>> +{
>> +    size_t cap_len = sizeof(PCIBridgeQemuCap);
>> +    PCIBridgeQemuCap cap;
>> +
>> +    cap.len = cap_len;
>> +    cap.bus_res = bus_reserve;
>> +    cap.io_lim = io_limit & 0xFF;
>> +    cap.io_lim_upper = io_limit >> 8 & 0xFFFF;
>> +    cap.mem_lim = mem_limit;
>> +    cap.pref_lim = pref_limit & 0xFFFF;
>> +    cap.pref_lim_upper = pref_limit >> 16 & 0xFFFFFFFF;
>> +
>> +    int offset = pci_add_capability(dev, PCI_CAP_ID_VNDR,
>> +                                    cap_offset, cap_len, errp);
>> +    if (offset < 0) {
>> +        return offset;
>> +    }
>> +
>> +    memcpy(dev->config + offset + 2, (char *)&cap + 2, cap_len - 2);
>> +    return 0;
>> +}
>> +
>>   static const TypeInfo pci_bridge_type_info = {
>>       .name = TYPE_PCI_BRIDGE,
>>       .parent = TYPE_PCI_DEVICE,
>> diff --git a/include/hw/pci/pci_bridge.h b/include/hw/pci/pci_bridge.h
>> index ff7cbaa..c9f642c 100644
>> --- a/include/hw/pci/pci_bridge.h
>> +++ b/include/hw/pci/pci_bridge.h
>> @@ -67,4 +67,22 @@ void pci_bridge_map_irq(PCIBridge *br, const char*
>> bus_name,
>>   #define  PCI_BRIDGE_CTL_DISCARD_STATUS        0x400   /* Discard timer
>> status */
>>   #define  PCI_BRIDGE_CTL_DISCARD_SERR  0x800   /* Discard timer SERR#
>> enable */
>>   +typedef struct PCIBridgeQemuCap {
>> +    uint8_t id;     /* Standard PCI capability header field */
>> +    uint8_t next;   /* Standard PCI capability header field */
>> +    uint8_t len;    /* Standard PCI vendor-specific capability header
>> field */
>> +    uint8_t bus_res;
>> +    uint32_t pref_lim_upper;
>> +    uint16_t pref_lim;
>> +    uint16_t mem_lim;
>>
>
> This 32bit IOMEM, right?
>
> +    uint16_t io_lim_upper;
>> +    uint8_t io_lim;
>>
>
> Why do we need io_lim and io_lim_upper?
>

The idea was to be able to directly move the capability fields values
to the registers when actually using it (in firmware) code.
Secondly, it saves a little space by avoding usage 32-bit types
when 24-bit ones are desired. And the same thing with prefetchable (48->64).
But if it's more convenient no to split this value, I can do that.



>
> Thanks,
> Marcel
>
>
> +    uint8_t padding;
>> +} PCIBridgeQemuCap;
>> +
>> +int pci_bridge_help_cap_init(PCIDevice *dev, int cap_offset,
>> +                              uint8_t bus_reserve, uint32_t io_limit,
>> +                              uint16_t mem_limit, uint64_t pref_limit,
>> +                              Error **errp);
>> +
>>   #endif /* QEMU_PCI_BRIDGE_H */
>>
>>
>


-- 
Alexander Bezzubikov
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.coreboot.org/pipermail/seabios/attachments/20170723/e8b10fa4/attachment.html>