cxl: Add AFU virtual PHB and kernel API

This patch does two things.

Firstly it presents the Accelerator Function Unit (AFUs) behind the POWER
Service Layer (PSL) as PCI devices on a virtual PCI Host Bridge (vPHB).  This
in in addition to the PSL being a PCI device itself.

As part of the Coherent Accelerator Interface Architecture (CAIA) AFUs can
provide an AFU configuration.  This AFU configuration recored is architected to
be the same as a PCI config space.

This patch sets discovers the AFU configuration records, provides AFU config
space read/write functions to these configuration records.  It then enumerates
the PCI bus.  It also hooks in PCI ops where appropriate.  It also destroys the
vPHB when the physical card is removed.

Secondly, it add an in kernel API for AFU to use CXL.  AFUs must present a
driver that firstly binds as a PCI device.  This PCI device can then be using
to do CXL specific operations (that can't sit in the PCI ops) using this API.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Acked-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 13 insertions, 4 deletions

diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
index 88de2ce79dca..416905ed174c 100644
--- a/drivers/misc/cxl/pci.c
+++ b/drivers/misc/cxl/pci.c
@@ -801,6 +801,9 @@ static int cxl_init_afu(struct cxl *adapter, int slice, struct pci_dev *dev)
 
 	adapter->afu[afu->slice] = afu;
 
+	if ((rc = cxl_pci_vphb_add(afu)))
+		dev_info(&afu->dev, "Can't register vPHB\n");
+
 	return 0;
 
 err_put2:
@@ -853,8 +856,10 @@ int cxl_reset(struct cxl *adapter)
 
 	dev_info(&dev->dev, "CXL reset\n");
 
-	for (i = 0; i < adapter->slices; i++)
+	for (i = 0; i < adapter->slices; i++) {
+		cxl_pci_vphb_remove(adapter->afu[i]);
 		cxl_remove_afu(adapter->afu[i]);
+	}
 
 	/* pcie_warm_reset requests a fundamental pci reset which includes a
 	 * PERST assert/deassert.  PERST triggers a loading of the image
@@ -1163,14 +1168,18 @@ static int cxl_probe(struct pci_dev *dev, const struct pci_device_id *id)
 static void cxl_remove(struct pci_dev *dev)
 {
 	struct cxl *adapter = pci_get_drvdata(dev);
-	int afu;
+	struct cxl_afu *afu;
+	int i;
 
 	/*
 	 * Lock to prevent someone grabbing a ref through the adapter list as
 	 * we are removing it
 	 */
-	for (afu = 0; afu < adapter->slices; afu++)
-		cxl_remove_afu(adapter->afu[afu]);
+	for (i = 0; i < adapter->slices; i++) {
+		afu = adapter->afu[i];
+		cxl_pci_vphb_remove(afu);
+		cxl_remove_afu(afu);
+	}
 	cxl_remove_adapter(adapter);
 }