[U-Boot] [PATCH 05/10] x86: mpspec: Allow platform to determine how PIRQ is connected to I/O APIC

[Bin Meng]

Hi Simon,

On Sat, Jul 18, 2015 at 10:37 PM, Simon Glass <sjg at chromium.org> wrote:
> Hi Bin,
>
> On 15 July 2015 at 02:23, Bin Meng <bmeng.cn at gmail.com> wrote:
>> Currently during writing MP table I/O interrupt assignment entry, we
>> assume the PIRQ is directly mapped to I/O APIC INTPIN#16-23, which
>> however is not always the case on some platforms.
>>
>> Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
>> ---
>>
>>  arch/x86/include/asm/mpspec.h | 17 +++++++++++++++++
>>  arch/x86/lib/mpspec.c         | 23 ++++++++++++++++-------
>>  2 files changed, 33 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/mpspec.h b/arch/x86/include/asm/mpspec.h
>> index efa9231..ad8eba9 100644
>> --- a/arch/x86/include/asm/mpspec.h
>> +++ b/arch/x86/include/asm/mpspec.h
>> @@ -432,6 +432,23 @@ void mp_write_compat_address_space(struct mp_config_table *mc, int busid,
>>  u32 mptable_finalize(struct mp_config_table *mc);
>>
>>  /**
>> + * mp_determine_pci_dstirq() - Determine PCI device's int pin on the I/O APIC
>> + *
>> + * This determines a PCI device's interrupt pin number on the I/O APIC.
>> + *
>> + * This can be implemented by platform codes to handle specifal cases, which
>> + * do not conform to the normal chipset/board design where PIRQ[A-H] are mapped
>> + * directly to I/O APIC INTPIN#16-23.
>> + *
>> + * @bus:       bus number of the pci device
>> + * @dev:       device number of the pci device
>> + * @func:      function number of the pci device
>> + * @pirq:      PIRQ number the PCI device's interrupt pin is routed to
>> + * @return:    interrupt pin number on the I/O APIC
>> + */
>> +int mp_determine_pci_dstirq(int bus, int dev, int func, int pirq);
>> +
>> +/**
>>   * write_mp_table() - Write MP table
>>   *
>>   * This writes MP table at a given address.
>> diff --git a/arch/x86/lib/mpspec.c b/arch/x86/lib/mpspec.c
>> index f16fbcb..f90567c 100644
>> --- a/arch/x86/lib/mpspec.c
>> +++ b/arch/x86/lib/mpspec.c
>> @@ -269,6 +269,12 @@ static bool check_dup_entry(struct mpc_config_intsrc *intsrc_base,
>>         return (i == entry_num) ? false : true;
>>  }
>>
>> +__weak int mp_determine_pci_dstirq(int bus, int dev, int func, int pirq)
>
> I'd like to avoid using weak functions. Can we use device tree or
> driver model instead?
>

As you can see in this patch
http://patchwork.ozlabs.org/patch/495524/, that the return value of
this function (dstirq) relies on the runtime value, so we cannot
describe it in the device tree. As for driver model, I am not sure if
if it suits. I will need think about it. If we do driver model, we
might be able to consolidate PIRQ and MP table codes. Can we leave
this to a possible future work?

> In principle we should be able to build all of the code in and boot an
> image on multiple boards. These sorts of things make it harder to
> understand and follow the code IMO.
>

Yep, ideally although I don't know how practical for now :-)

[snip]

Regards,
Bin