powerpc/powernv: Enable PCI peer-to-peer
authorFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Fri, 4 Aug 2017 09:55:14 +0000 (11:55 +0200)
committerMichael Ellerman <mpe@ellerman.id.au>
Tue, 8 Aug 2017 01:27:30 +0000 (11:27 +1000)
commit2552910084a5e12e280caf082ab01468e187a064
tree904561d1775f72de33bb2af0a9e1380dca6ed195
parent6ff4d3e9665274b69cff47f64cc20183465a1de2
powerpc/powernv: Enable PCI peer-to-peer

P9 has support for PCI peer-to-peer, enabling a device to write in the
MMIO space of another device directly, without interrupting the CPU.

This patch adds support for it on powernv, by adding a new API to be
called by drivers. The pnv_pci_set_p2p(...) call configures an
'initiator', i.e the device which will issue the MMIO operation, and a
'target', i.e. the device on the receiving side.

P9 really only supports MMIO stores for the time being but that's
expected to change in the future, so the API allows to define both
load and store operations.

  /* PCI p2p descriptor */
  #define OPAL_PCI_P2P_ENABLE           0x1
  #define OPAL_PCI_P2P_LOAD             0x2
  #define OPAL_PCI_P2P_STORE            0x4

  int pnv_pci_set_p2p(struct pci_dev *initiator, struct pci_dev *target,
                      u64 desc)

It uses a new OPAL call, as the configuration magic is done on the
PHBs by skiboot.

Signed-off-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Reviewed-by: Russell Currey <ruscur@russell.cc>
[mpe: Drop unrelated OPAL calls, s/uint64_t/u64/, minor formatting]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
arch/powerpc/include/asm/opal-api.h
arch/powerpc/include/asm/opal.h
arch/powerpc/include/asm/pnv-pci.h
arch/powerpc/platforms/powernv/opal-wrappers.S
arch/powerpc/platforms/powernv/pci-ioda.c
arch/powerpc/platforms/powernv/pci.c
arch/powerpc/platforms/powernv/pci.h