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, 269 insertions, 0 deletions

diff --git a/drivers/misc/cxl/vphb.c b/drivers/misc/cxl/vphb.c
new file mode 100644
index 000000000000..f733309b65d5
--- /dev/null
+++ b/drivers/misc/cxl/vphb.c
@@ -0,0 +1,269 @@
+/*
+ * Copyright 2014 IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/pci.h>
+#include <misc/cxl.h>
+#include "cxl.h"
+
+static int cxl_dma_set_mask(struct pci_dev *pdev, u64 dma_mask)
+{
+	if (dma_mask < DMA_BIT_MASK(64)) {
+		pr_info("%s only 64bit DMA supported on CXL", __func__);
+		return -EIO;
+	}
+
+	*(pdev->dev.dma_mask) = dma_mask;
+	return 0;
+}
+
+static int cxl_pci_probe_mode(struct pci_bus *bus)
+{
+	return PCI_PROBE_NORMAL;
+}
+
+static int cxl_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)
+{
+	return -ENODEV;
+}
+
+static void cxl_teardown_msi_irqs(struct pci_dev *pdev)
+{
+	/*
+	 * MSI should never be set but need still need to provide this call
+	 * back.
+	 */
+}
+
+static bool cxl_pci_enable_device_hook(struct pci_dev *dev)
+{
+	struct pci_controller *phb;
+	struct cxl_afu *afu;
+	struct cxl_context *ctx;
+
+	phb = pci_bus_to_host(dev->bus);
+	afu = (struct cxl_afu *)phb->private_data;
+	set_dma_ops(&dev->dev, &dma_direct_ops);
+	set_dma_offset(&dev->dev, PAGE_OFFSET);
+
+	/*
+	 * Allocate a context to do cxl things too.  If we eventually do real
+	 * DMA ops, we'll need a default context to attach them to
+	 */
+	ctx = cxl_dev_context_init(dev);
+	if (!ctx)
+		return false;
+	dev->dev.archdata.cxl_ctx = ctx;
+
+	return (cxl_afu_check_and_enable(afu) == 0);
+}
+
+static void cxl_pci_disable_device(struct pci_dev *dev)
+{
+	struct cxl_context *ctx = cxl_get_context(dev);
+
+	if (ctx) {
+		if (ctx->status == STARTED) {
+			dev_err(&dev->dev, "Default context started\n");
+			return;
+		}
+		cxl_release_context(ctx);
+	}
+}
+
+static resource_size_t cxl_pci_window_alignment(struct pci_bus *bus,
+						unsigned long type)
+{
+	return 1;
+}
+
+static void cxl_pci_reset_secondary_bus(struct pci_dev *dev)
+{
+	/* Should we do an AFU reset here ? */
+}
+
+static int cxl_pcie_cfg_record(u8 bus, u8 devfn)
+{
+	return (bus << 8) + devfn;
+}
+
+static unsigned long cxl_pcie_cfg_addr(struct pci_controller* phb,
+				       u8 bus, u8 devfn, int offset)
+{
+	int record = cxl_pcie_cfg_record(bus, devfn);
+
+	return (unsigned long)phb->cfg_addr + ((unsigned long)phb->cfg_data * record) + offset;
+}
+
+
+static int cxl_pcie_config_info(struct pci_bus *bus, unsigned int devfn,
+				int offset, int len,
+				volatile void __iomem **ioaddr,
+				u32 *mask, int *shift)
+{
+	struct pci_controller *phb;
+	struct cxl_afu *afu;
+	unsigned long addr;
+
+	phb = pci_bus_to_host(bus);
+	afu = (struct cxl_afu *)phb->private_data;
+	if (phb == NULL)
+		return PCIBIOS_DEVICE_NOT_FOUND;
+	if (cxl_pcie_cfg_record(bus->number, devfn) > afu->crs_num)
+		return PCIBIOS_DEVICE_NOT_FOUND;
+	if (offset >= (unsigned long)phb->cfg_data)
+		return PCIBIOS_BAD_REGISTER_NUMBER;
+	addr = cxl_pcie_cfg_addr(phb, bus->number, devfn, offset);
+
+	*ioaddr = (void *)(addr & ~0x3ULL);
+	*shift = ((addr & 0x3) * 8);
+	switch (len) {
+	case 1:
+		*mask = 0xff;
+		break;
+	case 2:
+		*mask = 0xffff;
+		break;
+	default:
+		*mask = 0xffffffff;
+		break;
+	}
+	return 0;
+}
+
+static int cxl_pcie_read_config(struct pci_bus *bus, unsigned int devfn,
+				int offset, int len, u32 *val)
+{
+	volatile void __iomem *ioaddr;
+	int shift, rc;
+	u32 mask;
+
+	rc = cxl_pcie_config_info(bus, devfn, offset, len, &ioaddr,
+				  &mask, &shift);
+	if (rc)
+		return rc;
+
+	/* Can only read 32 bits */
+	*val = (in_le32(ioaddr) >> shift) & mask;
+	return PCIBIOS_SUCCESSFUL;
+}
+
+static int cxl_pcie_write_config(struct pci_bus *bus, unsigned int devfn,
+				 int offset, int len, u32 val)
+{
+	volatile void __iomem *ioaddr;
+	u32 v, mask;
+	int shift, rc;
+
+	rc = cxl_pcie_config_info(bus, devfn, offset, len, &ioaddr,
+				  &mask, &shift);
+	if (rc)
+		return rc;
+
+	/* Can only write 32 bits so do read-modify-write */
+	mask <<= shift;
+	val <<= shift;
+
+	v = (in_le32(ioaddr) & ~mask) || (val & mask);
+
+	out_le32(ioaddr, v);
+	return PCIBIOS_SUCCESSFUL;
+}
+
+static struct pci_ops cxl_pcie_pci_ops =
+{
+	.read = cxl_pcie_read_config,
+	.write = cxl_pcie_write_config,
+};
+
+
+static struct pci_controller_ops cxl_pci_controller_ops =
+{
+	.probe_mode = cxl_pci_probe_mode,
+	.enable_device_hook = cxl_pci_enable_device_hook,
+	.disable_device = cxl_pci_disable_device,
+	.release_device = cxl_pci_disable_device,
+	.window_alignment = cxl_pci_window_alignment,
+	.reset_secondary_bus = cxl_pci_reset_secondary_bus,
+	.setup_msi_irqs = cxl_setup_msi_irqs,
+	.teardown_msi_irqs = cxl_teardown_msi_irqs,
+	.dma_set_mask = cxl_dma_set_mask,
+};
+
+int cxl_pci_vphb_add(struct cxl_afu *afu)
+{
+	struct pci_dev *phys_dev;
+	struct pci_controller *phb, *phys_phb;
+
+	phys_dev = to_pci_dev(afu->adapter->dev.parent);
+	phys_phb = pci_bus_to_host(phys_dev->bus);
+
+	/* Alloc and setup PHB data structure */
+	phb = pcibios_alloc_controller(phys_phb->dn);
+
+	if (!phb)
+		return -ENODEV;
+
+	/* Setup parent in sysfs */
+	phb->parent = &phys_dev->dev;
+
+	/* Setup the PHB using arch provided callback */
+	phb->ops = &cxl_pcie_pci_ops;
+	phb->cfg_addr = afu->afu_desc_mmio + afu->crs_offset;
+	phb->cfg_data = (void *)(u64)afu->crs_len;
+	phb->private_data = afu;
+	phb->controller_ops = cxl_pci_controller_ops;
+
+	/* Scan the bus */
+	pcibios_scan_phb(phb);
+	if (phb->bus == NULL)
+		return -ENXIO;
+
+	/* Claim resources. This might need some rework as well depending
+	 * whether we are doing probe-only or not, like assigning unassigned
+	 * resources etc...
+	 */
+	pcibios_claim_one_bus(phb->bus);
+
+	/* Add probed PCI devices to the device model */
+	pci_bus_add_devices(phb->bus);
+
+	afu->phb = phb;
+
+	return 0;
+}
+
+
+void cxl_pci_vphb_remove(struct cxl_afu *afu)
+{
+	struct pci_controller *phb;
+
+	/* If there is no configuration record we won't have one of these */
+	if (!afu || !afu->phb)
+		return;
+
+	phb = afu->phb;
+
+	pci_remove_root_bus(phb->bus);
+}
+
+struct cxl_afu *cxl_pci_to_afu(struct pci_dev *dev)
+{
+	struct pci_controller *phb;
+
+	phb = pci_bus_to_host(dev->bus);
+
+	return (struct cxl_afu *)phb->private_data;
+}
+EXPORT_SYMBOL_GPL(cxl_pci_to_afu);
+
+unsigned int cxl_pci_to_cfg_record(struct pci_dev *dev)
+{
+	return cxl_pcie_cfg_record(dev->bus->number, dev->devfn);
+}
+EXPORT_SYMBOL_GPL(cxl_pci_to_cfg_record);