Hi,
On 3/5/21 4:42 PM, Andy Shevchenko wrote:
> On Thu, Mar 4, 2021 at 3:47 PM Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
>> On 3/4/21 11:11 AM, Andy Shevchenko wrote:
>>> On Thu, Mar 4, 2021 at 8:36 AM Henning Schild
>>> <henning.schild@xxxxxxxxxxx> wrote:
>
> ...
>
>>>> +u32 simatic_ipc_get_membase0(unsigned int p2sb)
>>>> +{
>>>> + u32 bar0 = 0;
>>>
>>>> +#ifdef CONFIG_PCI
>>>
>>> It's ugly besides the fact that you have a dependency.
>>>
>>>> + struct pci_bus *bus;
>>>
>>> Missed blank line.
>>>
>>>> + /*
>>>> + * The GPIO memory is bar0 of the hidden P2SB device. Unhide the device
>>>> + * to have a quick look at it, before we hide it again.
>>>> + * Also grab the pci rescan lock so that device does not get discovered
>>>> + * and remapped while it is visible.
>>>> + * This code is inspired by drivers/mfd/lpc_ich.c
>>>> + */
>>>> + bus = pci_find_bus(0, 0);
>>>> + pci_lock_rescan_remove();
>>>> + pci_bus_write_config_byte(bus, p2sb, 0xE1, 0x0);
>>>> + pci_bus_read_config_dword(bus, p2sb, PCI_BASE_ADDRESS_0, &bar0);
>>>> +
>>>> + bar0 &= ~0xf;
>>>> + pci_bus_write_config_byte(bus, p2sb, 0xE1, 0x1);
>>>> + pci_unlock_rescan_remove();
>>>> +#endif /* CONFIG_PCI */
>>>> + return bar0;
>>>> +}
>>>> +EXPORT_SYMBOL(simatic_ipc_get_membase0);
>>>
>>> Oy vey! I know what this is and let's do it differently. I have some
>>> (relatively old) patch series I can send you privately for testing.
>>
>> This bit stood out the most to me too, it would be good if we can this fixed
>> in some cleaner work. So I'm curious how things will look with Andy's work
>> integrated.
>>
>> Also I don't think this should be exported. Instead this (or its replacement)
>> should be used to get the address for an IOMEM resource to add the platform
>> devices when they are instantiated. Then the platform-dev drivers can just
>> use the regular functions to get their resources instead of relying on this
>> module.
>
> I have published a WIP branch [1]. I have no means to test (I don't
> know what hardware at hand I can use right now), but I made it compile
> after 4 years of gathering dust...
So I took a quick look at the following 2 commits:
"platform/x86: p2sb: New Primary to Sideband bridge support library"
"mfd: lpc_ich: Switch to generic p2sb_bar()"
And this looks good to me, although compared to the code from this
patch-set you are missing the pci_lock_rescan_remove(); and
pci_unlock_rescan_remove(); calls.
> Feel free to give any kind of comments or share your ideas on how it
> can be improved (the above idea on IOMEM resource is interesting, but
> devices are PCI, not sure how this can be done).
The code added by this patch introduces a register_platform_devices()
function which creates a bunch of platform-devices; and then the
device-drivers for those call simatic_ipc_get_membase0() to get their
base-address.
My suggestion was to instead put the simatic_ipc_get_membase0() call
inside the code instantiating the platform devices and to add the
base-address for that pdev as IOMEM resource to the instantiated
platform-devices.
I hope this helps to clarify what I was trying to say.
Regards,
Hans
