[U-Boot] [PATCH 03/11] usb: ehci: generic PCI support

[Marek Vasut <marex@denx.de>]

Dear Vincent Palatin,

> On Thu, Dec 13, 2012 at 9:30 AM, Marek Vasut <marex@denx.de> wrote:
> > Dear Simon Glass,
> > 
> >> From: Vincent Palatin <vpalatin@chromium.org>
> >> 
> >> Instead of hardcoding the PCI IDs on the USB controller, use the PCI
> >> class to detect them.
> >> 
> >> Ensure the busmaster bit is properly set in the PCI configuration.
> >> 
> >> Signed-off-by: Simon Glass <sjg@chromium.org>
> >> ---
> >> 
> >>  drivers/usb/host/ehci-pci.c |   37
> >>  +++++++++++++++++++++++++++++++++++++ 1 files changed, 37
> >>  insertions(+), 0 deletions(-)
> >> 
> >> diff --git a/drivers/usb/host/ehci-pci.c b/drivers/usb/host/ehci-pci.c
> >> index 29af02d..0dc0e6e 100644
> >> --- a/drivers/usb/host/ehci-pci.c
> >> +++ b/drivers/usb/host/ehci-pci.c
> >> @@ -32,6 +32,34 @@ static struct pci_device_id ehci_pci_ids[] = {
> >> 
> >>       {0x12D8, 0x400F},       /* Pericom */
> >>       {0, 0}
> >>  
> >>  };
> >> 
> >> +#else
> >> +static pci_dev_t ehci_find_class(void)
> >> +{
> >> +     int bus;
> >> +     int devnum;
> >> +     pci_dev_t bdf;
> >> +     uint32_t class;
> >> +
> >> +     for (bus = 0; bus < pci_last_busno(); bus++) {
> >> +             for (devnum = 0; devnum < PCI_MAX_PCI_DEVICES-1; devnum++)
> >> { +                     pci_read_config_dword(PCI_BDF(bus, devnum, 0),
> >> +                                           PCI_CLASS_REVISION,
> >> &class); +                     if (class >> 16 == 0xffff)
> >> +                             continue;
> >> +
> >> +                     for (bdf = PCI_BDF(bus, devnum, 0);
> >> +                                     bdf <= PCI_BDF(bus, devnum,
> >> +                                             PCI_MAX_PCI_FUNCTIONS -
> >> 1); +                                     bdf += PCI_BDF(0, 0, 1)) { + 
> >>                            pci_read_config_dword(bdf,
> >> PCI_CLASS_REVISION, +                                                  
> >> &class);
> >> +                             if (class >> 8 == 0x0c0320)
> > 
> > Can we at least describe this magic please?
> 
> The PCI class word is something like that :
> class = [31:24] class code [23:16] subclass [15:8] Prog if [7:0] Revision
> ID For this use case :
> class code = 0x0C (Serial bus controller)
> subclass = 0x03 (USB controller)
> Program interface = 0x20 (EHCI)
> 
> This is available in include/pci_ids.h as "#define
> PCI_CLASS_SERIAL_USB_EHCI       0x0c0320"
> so just replacing the numeric constant by this define should be ok ?

Of course :)