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>

1 files changed, 5 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/powernv/pci.h b/arch/powerpc/platforms/powernv/pci.h
index f16bc403ec03..a95273c524f6 100644
--- a/arch/powerpc/platforms/powernv/pci.h
+++ b/arch/powerpc/platforms/powernv/pci.h
@@ -78,6 +78,9 @@ struct pnv_ioda_pe {
 	struct pnv_ioda_pe	*master;
 	struct list_head	slaves;
 
+	/* PCI peer-to-peer*/
+	int			p2p_initiator_count;
+
 	/* Link in list of PE#s */
 	struct list_head	list;
 };
@@ -189,6 +192,7 @@ struct pnv_phb {
 #ifdef CONFIG_CXL_BASE
 	struct cxl_afu *cxl_afu;
 #endif
+	int p2p_target_count;
 };
 
 extern struct pci_ops pnv_pci_ops;
@@ -229,6 +233,7 @@ extern void pnv_teardown_msi_irqs(struct pci_dev *pdev);
 extern struct pnv_ioda_pe *pnv_ioda_get_pe(struct pci_dev *dev);
 extern void pnv_set_msi_irq_chip(struct pnv_phb *phb, unsigned int virq);
 extern bool pnv_pci_enable_device_hook(struct pci_dev *dev);
+extern void pnv_pci_ioda2_set_bypass(struct pnv_ioda_pe *pe, bool enable);
 
 extern void pe_level_printk(const struct pnv_ioda_pe *pe, const char *level,
 			    const char *fmt, ...);