[PATCH 2/2] usb: xhci: Load Raspberry Pi 4 VL805's firmware

[Nicolas Saenz Julienne]

On Wed, 2020-04-29 at 14:05 +0200, Marek Vasut wrote:
> On 4/29/20 12:10 PM, Nicolas Saenz Julienne wrote:
> > On Tue, 2020-04-28 at 19:59 +0200, Marek Vasut wrote:
> > > On 4/28/20 7:44 PM, Nicolas Saenz Julienne wrote:
> > > > When needed, RPi4's co-processor (called VideoCore) has to be instructed
> > > > to load VL805's firmware (the chip providing xHCI support). VideCore's
> > > > firmware expects the board's PCIe bus to be already configured in order
> > > > for it to load the xHCI chip firmware. So we have to make sure this
> > > > happens in between the PCIe configuration and xHCI startup.
> > > > 
> > > > Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne at suse.de>
> > > > ---
> > > >  drivers/usb/host/xhci-pci.c | 6 ++++++
> > > >  1 file changed, 6 insertions(+)
> > > > 
> > > > diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
> > > > index c1f60da541..5c17ea6932 100644
> > > > --- a/drivers/usb/host/xhci-pci.c
> > > > +++ b/drivers/usb/host/xhci-pci.c
> > > > @@ -11,6 +11,8 @@
> > > >  #include <usb.h>
> > > >  #include <usb/xhci.h>
> > > >  
> > > > +#include <asm/arch/msg.h>
> > > > +
> > > >  static void xhci_pci_init(struct udevice *dev, struct xhci_hccr
> > > > **ret_hccr,
> > > >  			  struct xhci_hcor **ret_hcor)
> > > >  {
> > > > @@ -18,6 +20,10 @@ static void xhci_pci_init(struct udevice *dev, struct
> > > > xhci_hccr **ret_hccr,
> > > >  	struct xhci_hcor *hcor;
> > > >  	u32 cmd;
> > > >  
> > > > +#ifdef CONFIG_BCM2711
> > > > +	bcm2711_load_vl805_firmware();
> > > > +#endif
> > > > +
> > > >  	hccr = (struct xhci_hccr *)dm_pci_map_bar(dev,
> > > >  			PCI_BASE_ADDRESS_0, PCI_REGION_MEM);
> > > >  	hcor = (struct xhci_hcor *)((uintptr_t) hccr +
> > > 
> > > I think socfpga arria10 has some firmware loader implementation that is
> > > generic, so can't we use that ?
> > 
> > I don't think so. I've been told the firmware upgrade protocol is private
> > and
> > specific to the VL80X family of devices. The Raspberry Pi foundation decided
> > to
> > implement it in their closed source VideoCore firmware.
> 
> What I meant was that U-Boot has a way to load files from various
> storage roughly the same way Linux firmware loader API does.

As far as generic APIs are concerned I've had a look at
request_firmware_into_buf() which socfpga uses in its spl_board_init(). But
sadly it doesn't help here.

What bcm2711_load_vl805_firmware() does here is just informing the co-processor
that it's free to start the VL805 firmware load operation. I'm by no means
providing anything, think of it as a doorbell if you will. I'll try to find an
alternative to 'load' in the function name so the distinction with regular
firmware loading is more explicit.

Also bare in mind we have to time this operation in between PCIe configuration
and xHCI init. Which, IIUC, blocks us from using board_init() and the likes of
it (which would be way nicer IMO).

Regards,
Nicolas

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