powerpc/powernv: Add support for Nvlink NPUs

NVLink is a high speed interconnect that is used in conjunction with a
PCI-E connection to create an interface between CPU and GPU that
provides very high data bandwidth. A PCI-E connection to a GPU is used
as the control path to initiate and report status of large data
transfers sent via the NVLink.

On IBM Power systems the NVLink processing unit (NPU) is similar to
the existing PHB3. This patch adds support for a new NPU PHB type. DMA
operations on the NPU are not supported as this patch sets the TCE
translation tables to be the same as the related GPU PCIe device for
each NVLink. Therefore all DMA operations are setup and controlled via
the PCIe device.

EEH is not presently supported for the NPU devices, although it may be
added in future.

Signed-off-by: Alistair Popple <alistair@popple.id.au>
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 348 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/powernv/npu-dma.c b/arch/powerpc/platforms/powernv/npu-dma.c
new file mode 100644
index 000000000000..e85aa900f5c0
--- /dev/null
+++ b/arch/powerpc/platforms/powernv/npu-dma.c
@@ -0,0 +1,348 @@
+/*
+ * This file implements the DMA operations for NVLink devices. The NPU
+ * devices all point to the same iommu table as the parent PCI device.
+ *
+ * Copyright Alistair Popple, IBM Corporation 2015.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ */
+
+#include <linux/export.h>
+#include <linux/pci.h>
+#include <linux/memblock.h>
+
+#include <asm/iommu.h>
+#include <asm/pnv-pci.h>
+#include <asm/msi_bitmap.h>
+#include <asm/opal.h>
+
+#include "powernv.h"
+#include "pci.h"
+
+/*
+ * Other types of TCE cache invalidation are not functional in the
+ * hardware.
+ */
+#define TCE_KILL_INVAL_ALL PPC_BIT(0)
+
+static struct pci_dev *get_pci_dev(struct device_node *dn)
+{
+	return PCI_DN(dn)->pcidev;
+}
+
+/* Given a NPU device get the associated PCI device. */
+struct pci_dev *pnv_pci_get_gpu_dev(struct pci_dev *npdev)
+{
+	struct device_node *dn;
+	struct pci_dev *gpdev;
+
+	/* Get assoicated PCI device */
+	dn = of_parse_phandle(npdev->dev.of_node, "ibm,gpu", 0);
+	if (!dn)
+		return NULL;
+
+	gpdev = get_pci_dev(dn);
+	of_node_put(dn);
+
+	return gpdev;
+}
+EXPORT_SYMBOL(pnv_pci_get_gpu_dev);
+
+/* Given the real PCI device get a linked NPU device. */
+struct pci_dev *pnv_pci_get_npu_dev(struct pci_dev *gpdev, int index)
+{
+	struct device_node *dn;
+	struct pci_dev *npdev;
+
+	/* Get assoicated PCI device */
+	dn = of_parse_phandle(gpdev->dev.of_node, "ibm,npu", index);
+	if (!dn)
+		return NULL;
+
+	npdev = get_pci_dev(dn);
+	of_node_put(dn);
+
+	return npdev;
+}
+EXPORT_SYMBOL(pnv_pci_get_npu_dev);
+
+#define NPU_DMA_OP_UNSUPPORTED()					\
+	dev_err_once(dev, "%s operation unsupported for NVLink devices\n", \
+		__func__)
+
+static void *dma_npu_alloc(struct device *dev, size_t size,
+			   dma_addr_t *dma_handle, gfp_t flag,
+			   struct dma_attrs *attrs)
+{
+	NPU_DMA_OP_UNSUPPORTED();
+	return NULL;
+}
+
+static void dma_npu_free(struct device *dev, size_t size,
+			 void *vaddr, dma_addr_t dma_handle,
+			 struct dma_attrs *attrs)
+{
+	NPU_DMA_OP_UNSUPPORTED();
+}
+
+static dma_addr_t dma_npu_map_page(struct device *dev, struct page *page,
+				   unsigned long offset, size_t size,
+				   enum dma_data_direction direction,
+				   struct dma_attrs *attrs)
+{
+	NPU_DMA_OP_UNSUPPORTED();
+	return 0;
+}
+
+static int dma_npu_map_sg(struct device *dev, struct scatterlist *sglist,
+			  int nelems, enum dma_data_direction direction,
+			  struct dma_attrs *attrs)
+{
+	NPU_DMA_OP_UNSUPPORTED();
+	return 0;
+}
+
+static int dma_npu_dma_supported(struct device *dev, u64 mask)
+{
+	NPU_DMA_OP_UNSUPPORTED();
+	return 0;
+}
+
+static u64 dma_npu_get_required_mask(struct device *dev)
+{
+	NPU_DMA_OP_UNSUPPORTED();
+	return 0;
+}
+
+struct dma_map_ops dma_npu_ops = {
+	.map_page		= dma_npu_map_page,
+	.map_sg			= dma_npu_map_sg,
+	.alloc			= dma_npu_alloc,
+	.free			= dma_npu_free,
+	.dma_supported		= dma_npu_dma_supported,
+	.get_required_mask	= dma_npu_get_required_mask,
+};
+
+/*
+ * Returns the PE assoicated with the PCI device of the given
+ * NPU. Returns the linked pci device if pci_dev != NULL.
+ */
+static struct pnv_ioda_pe *get_gpu_pci_dev_and_pe(struct pnv_ioda_pe *npe,
+						  struct pci_dev **gpdev)
+{
+	struct pnv_phb *phb;
+	struct pci_controller *hose;
+	struct pci_dev *pdev;
+	struct pnv_ioda_pe *pe;
+	struct pci_dn *pdn;
+
+	if (npe->flags & PNV_IODA_PE_PEER) {
+		pe = npe->peers[0];
+		pdev = pe->pdev;
+	} else {
+		pdev = pnv_pci_get_gpu_dev(npe->pdev);
+		if (!pdev)
+			return NULL;
+
+		pdn = pci_get_pdn(pdev);
+		if (WARN_ON(!pdn || pdn->pe_number == IODA_INVALID_PE))
+			return NULL;
+
+		hose = pci_bus_to_host(pdev->bus);
+		phb = hose->private_data;
+		pe = &phb->ioda.pe_array[pdn->pe_number];
+	}
+
+	if (gpdev)
+		*gpdev = pdev;
+
+	return pe;
+}
+
+void pnv_npu_tce_invalidate_entire(struct pnv_ioda_pe *npe)
+{
+	struct pnv_phb *phb = npe->phb;
+
+	if (WARN_ON(phb->type != PNV_PHB_NPU ||
+		    !phb->ioda.tce_inval_reg ||
+		    !(npe->flags & PNV_IODA_PE_DEV)))
+		return;
+
+	mb(); /* Ensure previous TCE table stores are visible */
+	__raw_writeq(cpu_to_be64(TCE_KILL_INVAL_ALL),
+		phb->ioda.tce_inval_reg);
+}
+
+void pnv_npu_tce_invalidate(struct pnv_ioda_pe *npe,
+				struct iommu_table *tbl,
+				unsigned long index,
+				unsigned long npages,
+				bool rm)
+{
+	struct pnv_phb *phb = npe->phb;
+
+	/* We can only invalidate the whole cache on NPU */
+	unsigned long val = TCE_KILL_INVAL_ALL;
+
+	if (WARN_ON(phb->type != PNV_PHB_NPU ||
+		    !phb->ioda.tce_inval_reg ||
+		    !(npe->flags & PNV_IODA_PE_DEV)))
+		return;
+
+	mb(); /* Ensure previous TCE table stores are visible */
+	if (rm)
+		__raw_rm_writeq(cpu_to_be64(val),
+		  (__be64 __iomem *) phb->ioda.tce_inval_reg_phys);
+	else
+		__raw_writeq(cpu_to_be64(val),
+			phb->ioda.tce_inval_reg);
+}
+
+void pnv_npu_init_dma_pe(struct pnv_ioda_pe *npe)
+{
+	struct pnv_ioda_pe *gpe;
+	struct pci_dev *gpdev;
+	int i, avail = -1;
+
+	if (!npe->pdev || !(npe->flags & PNV_IODA_PE_DEV))
+		return;
+
+	gpe = get_gpu_pci_dev_and_pe(npe, &gpdev);
+	if (!gpe)
+		return;
+
+	for (i = 0; i < PNV_IODA_MAX_PEER_PES; i++) {
+		/* Nothing to do if the PE is already connected. */
+		if (gpe->peers[i] == npe)
+			return;
+
+		if (!gpe->peers[i])
+			avail = i;
+	}
+
+	if (WARN_ON(avail < 0))
+		return;
+
+	gpe->peers[avail] = npe;
+	gpe->flags |= PNV_IODA_PE_PEER;
+
+	/*
+	 * We assume that the NPU devices only have a single peer PE
+	 * (the GPU PCIe device PE).
+	 */
+	npe->peers[0] = gpe;
+	npe->flags |= PNV_IODA_PE_PEER;
+}
+
+/*
+ * For the NPU we want to point the TCE table at the same table as the
+ * real PCI device.
+ */
+static void pnv_npu_disable_bypass(struct pnv_ioda_pe *npe)
+{
+	struct pnv_phb *phb = npe->phb;
+	struct pci_dev *gpdev;
+	struct pnv_ioda_pe *gpe;
+	void *addr;
+	unsigned int size;
+	int64_t rc;
+
+	/*
+	 * Find the assoicated PCI devices and get the dma window
+	 * information from there.
+	 */
+	if (!npe->pdev || !(npe->flags & PNV_IODA_PE_DEV))
+		return;
+
+	gpe = get_gpu_pci_dev_and_pe(npe, &gpdev);
+	if (!gpe)
+		return;
+
+	addr = (void *)gpe->table_group.tables[0]->it_base;
+	size = gpe->table_group.tables[0]->it_size << 3;
+	rc = opal_pci_map_pe_dma_window(phb->opal_id, npe->pe_number,
+					npe->pe_number, 1, __pa(addr),
+					size, 0x1000);
+	if (rc != OPAL_SUCCESS)
+		pr_warn("%s: Error %lld setting DMA window on PHB#%d-PE#%d\n",
+			__func__, rc, phb->hose->global_number, npe->pe_number);
+
+	/*
+	 * We don't initialise npu_pe->tce32_table as we always use
+	 * dma_npu_ops which are nops.
+	 */
+	set_dma_ops(&npe->pdev->dev, &dma_npu_ops);
+}
+
+/*
+ * Enable/disable bypass mode on the NPU. The NPU only supports one
+ * window per link, so bypass needs to be explicity enabled or
+ * disabled. Unlike for a PHB3 bypass and non-bypass modes can't be
+ * active at the same time.
+ */
+int pnv_npu_dma_set_bypass(struct pnv_ioda_pe *npe, bool enable)
+{
+	struct pnv_phb *phb = npe->phb;
+	int64_t rc = 0;
+
+	if (phb->type != PNV_PHB_NPU || !npe->pdev)
+		return -EINVAL;
+
+	if (enable) {
+		/* Enable the bypass window */
+		phys_addr_t top = memblock_end_of_DRAM();
+
+		npe->tce_bypass_base = 0;
+		top = roundup_pow_of_two(top);
+		dev_info(&npe->pdev->dev, "Enabling bypass for PE %d\n",
+			 npe->pe_number);
+		rc = opal_pci_map_pe_dma_window_real(phb->opal_id,
+					npe->pe_number, npe->pe_number,
+					npe->tce_bypass_base, top);
+	} else {
+		/*
+		 * Disable the bypass window by replacing it with the
+		 * TCE32 window.
+		 */
+		pnv_npu_disable_bypass(npe);
+	}
+
+	return rc;
+}
+
+int pnv_npu_dma_set_mask(struct pci_dev *npdev, u64 dma_mask)
+{
+	struct pci_controller *hose = pci_bus_to_host(npdev->bus);
+	struct pnv_phb *phb = hose->private_data;
+	struct pci_dn *pdn = pci_get_pdn(npdev);
+	struct pnv_ioda_pe *npe, *gpe;
+	struct pci_dev *gpdev;
+	uint64_t top;
+	bool bypass = false;
+
+	if (WARN_ON(!pdn || pdn->pe_number == IODA_INVALID_PE))
+		return -ENXIO;
+
+	/* We only do bypass if it's enabled on the linked device */
+	npe = &phb->ioda.pe_array[pdn->pe_number];
+	gpe = get_gpu_pci_dev_and_pe(npe, &gpdev);
+	if (!gpe)
+		return -ENODEV;
+
+	if (gpe->tce_bypass_enabled) {
+		top = gpe->tce_bypass_base + memblock_end_of_DRAM() - 1;
+		bypass = (dma_mask >= top);
+	}
+
+	if (bypass)
+		dev_info(&npdev->dev, "Using 64-bit DMA iommu bypass\n");
+	else
+		dev_info(&npdev->dev, "Using 32-bit DMA via iommu\n");
+
+	pnv_npu_dma_set_bypass(npe, bypass);
+	*npdev->dev.dma_mask = dma_mask;
+
+	return 0;
+}