[PATCH v4 10/25] nvdimm: Add driver for OpenCAPI Persistent Memory

["Alastair D'Silva" <alastair@d-silva.org>]

This driver exposes LPC memory on OpenCAPI pmem cards
as an NVDIMM, allowing the existing nvram infrastructure
to be used.

Namespace metadata is stored on the media itself, so
scm_reserve_metadata() maps 1 section's worth of PMEM storage
at the start to hold this. The rest of the PMEM range is registered
with libnvdimm as an nvdimm. ndctl_config_read/write/size() provide
callbacks to libnvdimm to access the metadata.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 drivers/nvdimm/Kconfig         |   2 +
 drivers/nvdimm/Makefile        |   1 +
 drivers/nvdimm/ocxl/Kconfig    |  15 ++
 drivers/nvdimm/ocxl/Makefile   |   7 +
 drivers/nvdimm/ocxl/main.c     | 476 +++++++++++++++++++++++++++++++++
 drivers/nvdimm/ocxl/ocxlpmem.h |  23 ++
 6 files changed, 524 insertions(+)
 create mode 100644 drivers/nvdimm/ocxl/Kconfig
 create mode 100644 drivers/nvdimm/ocxl/Makefile
 create mode 100644 drivers/nvdimm/ocxl/main.c
 create mode 100644 drivers/nvdimm/ocxl/ocxlpmem.h

diff --git a/drivers/nvdimm/Kconfig b/drivers/nvdimm/Kconfig
index b7d1eb38b27d..368328637182 100644
--- a/drivers/nvdimm/Kconfig
+++ b/drivers/nvdimm/Kconfig
@@ -131,4 +131,6 @@ config NVDIMM_TEST_BUILD
 	  core devm_memremap_pages() implementation and other
 	  infrastructure.
 
+source "drivers/nvdimm/ocxl/Kconfig"
+
 endif
diff --git a/drivers/nvdimm/Makefile b/drivers/nvdimm/Makefile
index 29203f3d3069..bc02be11c794 100644
--- a/drivers/nvdimm/Makefile
+++ b/drivers/nvdimm/Makefile
@@ -33,3 +33,4 @@ libnvdimm-$(CONFIG_NVDIMM_KEYS) += security.o
 TOOLS := ../../tools
 TEST_SRC := $(TOOLS)/testing/nvdimm/test
 obj-$(CONFIG_NVDIMM_TEST_BUILD) += $(TEST_SRC)/iomap.o
+obj-$(CONFIG_LIBNVDIMM) += ocxl/
diff --git a/drivers/nvdimm/ocxl/Kconfig b/drivers/nvdimm/ocxl/Kconfig
new file mode 100644
index 000000000000..c5d927520920
--- /dev/null
+++ b/drivers/nvdimm/ocxl/Kconfig
@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: GPL-2.0-only
+if LIBNVDIMM
+
+config OCXL_PMEM
+	tristate "OpenCAPI Persistent Memory"
+	depends on LIBNVDIMM && PPC_POWERNV && PCI && EEH && ZONE_DEVICE && OCXL
+	help
+	  Exposes devices that implement the OpenCAPI Storage Class Memory
+	  specification as persistent memory regions. You may also want
+	  DEV_DAX, DEV_DAX_PMEM & FS_DAX if you plan on using DAX devices
+	  stacked on top of this driver.
+
+	  Select N if unsure.
+
+endif
diff --git a/drivers/nvdimm/ocxl/Makefile b/drivers/nvdimm/ocxl/Makefile
new file mode 100644
index 000000000000..e0e8ade1987a
--- /dev/null
+++ b/drivers/nvdimm/ocxl/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+
+ccflags-$(CONFIG_PPC_WERROR)	+= -Werror
+
+obj-$(CONFIG_OCXL_PMEM) += ocxlpmem.o
+
+ocxlpmem-y := main.o
\ No newline at end of file
diff --git a/drivers/nvdimm/ocxl/main.c b/drivers/nvdimm/ocxl/main.c
new file mode 100644
index 000000000000..c0066fedf9cc
--- /dev/null
+++ b/drivers/nvdimm/ocxl/main.c
@@ -0,0 +1,476 @@
+// SPDX-License-Identifier: GPL-2.0+
+// Copyright 2020 IBM Corp.
+
+/*
+ * A driver for OpenCAPI devices that implement the Storage Class
+ * Memory specification.
+ */
+
+#include <linux/module.h>
+#include <misc/ocxl.h>
+#include <linux/ndctl.h>
+#include <linux/mm_types.h>
+#include <linux/memory_hotplug.h>
+#include "ocxlpmem.h"
+
+static const struct pci_device_id pci_tbl[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_IBM, 0x0625), },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(pci, pci_tbl);
+
+#define NUM_MINORS 256 // Total to reserve
+
+static dev_t ocxlpmem_dev;
+static struct class *ocxlpmem_class;
+static struct mutex minors_idr_lock;
+static struct idr minors_idr;
+
+/**
+ * ndctl_config_write() - Handle a ND_CMD_SET_CONFIG_DATA command from ndctl
+ * @ocxlpmem: the device metadata
+ * @command: the incoming data to write
+ * Return: 0 on success, negative on failure
+ */
+static int ndctl_config_write(struct ocxlpmem *ocxlpmem,
+			      struct nd_cmd_set_config_hdr *command)
+{
+	if (command->in_offset + command->in_length > LABEL_AREA_SIZE)
+		return -EINVAL;
+
+	memcpy_flushcache(ocxlpmem->metadata_addr + command->in_offset,
+			  command->in_buf, command->in_length);
+
+	return 0;
+}
+
+/**
+ * ndctl_config_read() - Handle a ND_CMD_GET_CONFIG_DATA command from ndctl
+ * @ocxlpmem: the device metadata
+ * @command: the read request
+ * Return: 0 on success, negative on failure
+ */
+static int ndctl_config_read(struct ocxlpmem *ocxlpmem,
+			     struct nd_cmd_get_config_data_hdr *command)
+{
+	if (command->in_offset + command->in_length > LABEL_AREA_SIZE)
+		return -EINVAL;
+
+	memcpy_mcsafe(command->out_buf,
+		      ocxlpmem->metadata_addr + command->in_offset,
+		      command->in_length);
+
+	return 0;
+}
+
+/**
+ * ndctl_config_size() - Handle a ND_CMD_GET_CONFIG_SIZE command from ndctl
+ * @command: the read request
+ * Return: 0 on success, negative on failure
+ */
+static int ndctl_config_size(struct nd_cmd_get_config_size *command)
+{
+	command->status = 0;
+	command->config_size = LABEL_AREA_SIZE;
+	command->max_xfer = PAGE_SIZE;
+
+	return 0;
+}
+
+static int ndctl(struct nvdimm_bus_descriptor *nd_desc,
+		 struct nvdimm *nvdimm,
+		 unsigned int cmd, void *buf, unsigned int buf_len, int *cmd_rc)
+{
+	struct ocxlpmem *ocxlpmem = container_of(nd_desc,
+						 struct ocxlpmem, bus_desc);
+
+	switch (cmd) {
+	case ND_CMD_GET_CONFIG_SIZE:
+		*cmd_rc = ndctl_config_size(buf);
+		return 0;
+
+	case ND_CMD_GET_CONFIG_DATA:
+		*cmd_rc = ndctl_config_read(ocxlpmem, buf);
+		return 0;
+
+	case ND_CMD_SET_CONFIG_DATA:
+		*cmd_rc = ndctl_config_write(ocxlpmem, buf);
+		return 0;
+
+	default:
+		return -ENOTTY;
+	}
+}
+
+/**
+ * reserve_metadata() - Reserve space for nvdimm metadata
+ * @ocxlpmem: the device metadata
+ * @lpc_mem: The resource representing the LPC memory of the OpenCAPI device
+ */
+static int reserve_metadata(struct ocxlpmem *ocxlpmem,
+			    struct resource *lpc_mem)
+{
+	ocxlpmem->metadata_addr = devm_memremap(&ocxlpmem->dev, lpc_mem->start,
+						LABEL_AREA_SIZE, MEMREMAP_WB);
+	if (IS_ERR(ocxlpmem->metadata_addr))
+		return PTR_ERR(ocxlpmem->metadata_addr);
+
+	return 0;
+}
+
+/**
+ * register_lpc_mem() - Discover persistent memory on a device and register it with the NVDIMM subsystem
+ * @ocxlpmem: the device metadata
+ * Return: 0 on success
+ */
+static int register_lpc_mem(struct ocxlpmem *ocxlpmem)
+{
+	struct nd_region_desc region_desc;
+	struct nd_mapping_desc nd_mapping_desc;
+	struct resource *lpc_mem;
+	const struct ocxl_afu_config *config;
+	const struct ocxl_fn_config *fn_config;
+	int rc;
+	unsigned long nvdimm_cmd_mask = 0;
+	unsigned long nvdimm_flags = 0;
+	int target_node;
+	char serial[16 + 1];
+
+	// Set up the reserved metadata area
+	rc = ocxl_afu_map_lpc_mem(ocxlpmem->ocxl_afu);
+	if (rc < 0)
+		return rc;
+
+	lpc_mem = ocxl_afu_lpc_mem(ocxlpmem->ocxl_afu);
+	if (!lpc_mem || !lpc_mem->start)
+		return -EINVAL;
+
+	config = ocxl_afu_config(ocxlpmem->ocxl_afu);
+	fn_config = ocxl_function_config(ocxlpmem->ocxl_fn);
+
+	rc = reserve_metadata(ocxlpmem, lpc_mem);
+	if (rc)
+		return rc;
+
+	ocxlpmem->bus_desc.provider_name = "ocxlpmem";
+	ocxlpmem->bus_desc.ndctl = ndctl;
+	ocxlpmem->bus_desc.module = THIS_MODULE;
+
+	ocxlpmem->nvdimm_bus = nvdimm_bus_register(&ocxlpmem->dev,
+						   &ocxlpmem->bus_desc);
+	if (!ocxlpmem->nvdimm_bus)
+		return -EINVAL;
+
+	ocxlpmem->pmem_res.start = (u64)lpc_mem->start + LABEL_AREA_SIZE;
+	ocxlpmem->pmem_res.end = (u64)lpc_mem->start + config->lpc_mem_size - 1;
+	ocxlpmem->pmem_res.name = "OpenCAPI persistent memory";
+
+	set_bit(ND_CMD_GET_CONFIG_SIZE, &nvdimm_cmd_mask);
+	set_bit(ND_CMD_GET_CONFIG_DATA, &nvdimm_cmd_mask);
+	set_bit(ND_CMD_SET_CONFIG_DATA, &nvdimm_cmd_mask);
+
+	set_bit(NDD_ALIASING, &nvdimm_flags);
+
+	snprintf(serial, sizeof(serial), "%llx", fn_config->serial);
+	nd_mapping_desc.nvdimm = nvdimm_create(ocxlpmem->nvdimm_bus, ocxlpmem,
+					       NULL, nvdimm_flags,
+					       nvdimm_cmd_mask, 0, NULL);
+	if (!nd_mapping_desc.nvdimm)
+		return -ENOMEM;
+
+	if (nvdimm_bus_check_dimm_count(ocxlpmem->nvdimm_bus, 1))
+		return -EINVAL;
+
+	nd_mapping_desc.start = ocxlpmem->pmem_res.start;
+	nd_mapping_desc.size = resource_size(&ocxlpmem->pmem_res);
+	nd_mapping_desc.position = 0;
+
+	ocxlpmem->nd_set.cookie1 = fn_config->serial;
+	ocxlpmem->nd_set.cookie2 = fn_config->serial;
+
+	target_node = of_node_to_nid(ocxlpmem->pdev->dev.of_node);
+
+	memset(&region_desc, 0, sizeof(region_desc));
+	region_desc.res = &ocxlpmem->pmem_res;
+	region_desc.numa_node = NUMA_NO_NODE;
+	region_desc.target_node = target_node;
+	region_desc.num_mappings = 1;
+	region_desc.mapping = &nd_mapping_desc;
+	region_desc.nd_set = &ocxlpmem->nd_set;
+
+	set_bit(ND_REGION_PAGEMAP, &region_desc.flags);
+	/*
+	 * NB: libnvdimm copies the data from ndr_desc into it's own
+	 * structures so passing a stack pointer is fine.
+	 */
+	ocxlpmem->nd_region = nvdimm_pmem_region_create(ocxlpmem->nvdimm_bus,
+							&region_desc);
+	if (!ocxlpmem->nd_region)
+		return -EINVAL;
+
+	dev_info(&ocxlpmem->dev,
+		 "Onlining %lluMB of persistent memory\n",
+		 nd_mapping_desc.size / SZ_1M);
+
+	return 0;
+}
+
+/**
+ * allocate_minor() - Allocate a minor number to use for an OpenCAPI pmem device
+ * @ocxlpmem: the device metadata
+ * Return: the allocated minor number
+ */
+static int allocate_minor(struct ocxlpmem *ocxlpmem)
+{
+	int minor;
+
+	mutex_lock(&minors_idr_lock);
+	minor = idr_alloc(&minors_idr, ocxlpmem, 0, NUM_MINORS, GFP_KERNEL);
+	mutex_unlock(&minors_idr_lock);
+	return minor;
+}
+
+static void free_minor(struct ocxlpmem *ocxlpmem)
+{
+	mutex_lock(&minors_idr_lock);
+	idr_remove(&minors_idr, MINOR(ocxlpmem->dev.devt));
+	mutex_unlock(&minors_idr_lock);
+}
+
+/**
+ * free_ocxlpmem() - Free all members of an ocxlpmem struct
+ * @ocxlpmem: the device struct to clear
+ */
+static void free_ocxlpmem(struct ocxlpmem *ocxlpmem)
+{
+	int rc;
+
+	free_minor(ocxlpmem);
+
+	if (ocxlpmem->ocxl_context) {
+		rc = ocxl_context_detach(ocxlpmem->ocxl_context);
+		if (rc == -EBUSY)
+			dev_warn(&ocxlpmem->dev, "Timeout detaching ocxl context\n");
+		else
+			ocxl_context_free(ocxlpmem->ocxl_context);
+	}
+
+	if (ocxlpmem->ocxl_afu)
+		ocxl_afu_put(ocxlpmem->ocxl_afu);
+
+	if (ocxlpmem->ocxl_fn)
+		ocxl_function_close(ocxlpmem->ocxl_fn);
+
+	pci_dev_put(ocxlpmem->pdev);
+
+	kfree(ocxlpmem);
+}
+
+/**
+ * free_ocxlpmem_dev() - Free an OpenCAPI persistent memory device
+ * @dev: The device struct
+ */
+static void free_ocxlpmem_dev(struct device *dev)
+{
+	struct ocxlpmem *ocxlpmem = container_of(dev, struct ocxlpmem, dev);
+
+	free_ocxlpmem(ocxlpmem);
+}
+
+/**
+ * ocxlpmem_register() - Register an OpenCAPI pmem device with the kernel
+ * @ocxlpmem: the device metadata
+ * Return: 0 on success, negative on failure
+ */
+static int ocxlpmem_register(struct ocxlpmem *ocxlpmem)
+{
+	int rc;
+	int minor = allocate_minor(ocxlpmem);
+
+	if (minor < 0)
+		return minor;
+
+	ocxlpmem->dev.release = free_ocxlpmem_dev;
+	rc = dev_set_name(&ocxlpmem->dev, "ocxlpmem%d", minor);
+	if (rc < 0)
+		return rc;
+
+	ocxlpmem->dev.devt = MKDEV(MAJOR(ocxlpmem_dev), minor);
+	ocxlpmem->dev.class = ocxlpmem_class;
+	ocxlpmem->dev.parent = &ocxlpmem->pdev->dev;
+
+	return device_register(&ocxlpmem->dev);
+}
+
+/**
+ * ocxlpmem_remove() - Free an OpenCAPI persistent memory device
+ * @pdev: the PCI device information struct
+ */
+static void remove(struct pci_dev *pdev)
+{
+	if (PCI_FUNC(pdev->devfn) == 0) {
+		struct ocxl_fn *func0 = pci_get_drvdata(pdev);
+
+		if (func0)
+			ocxl_function_close(func0);
+	} else {
+		struct ocxlpmem *ocxlpmem = pci_get_drvdata(pdev);
+
+		if (!ocxlpmem)
+			return;
+
+		if (ocxlpmem->nvdimm_bus)
+			nvdimm_bus_unregister(ocxlpmem->nvdimm_bus);
+
+		device_unregister(&ocxlpmem->dev);
+	}
+}
+
+/**
+ * probe_function0() - Set up function 0 for an OpenCAPI persistent memory device
+ * This is important as it enables templates higher than 0 across all other
+ * functions, which in turn enables higher bandwidth accesses
+ * @pdev: the PCI device information struct
+ * Return: 0 on success, negative on failure
+ */
+static int probe_function0(struct pci_dev *pdev)
+{
+	struct ocxl_fn *fn;
+
+	fn = ocxl_function_open(pdev);
+	if (IS_ERR(fn)) {
+		dev_err(&pdev->dev, "failed to open OCXL function\n");
+		return PTR_ERR(fn);
+	}
+
+	pci_set_drvdata(pdev, fn);
+
+	return 0;
+}
+
+/**
+ * probe() - Init an OpenCAPI persistent memory device
+ * @pdev: the PCI device information struct
+ * @ent: The entry from ocxlpmem_pci_tbl
+ * Return: 0 on success, negative on failure
+ */
+static int probe(struct pci_dev *pdev, const struct pci_device_id *ent)
+{
+	struct ocxlpmem *ocxlpmem;
+	int rc;
+
+	if (PCI_FUNC(pdev->devfn) == 0)
+		return probe_function0(pdev);
+	else if (PCI_FUNC(pdev->devfn) != 1)
+		return 0;
+
+	ocxlpmem = kzalloc(sizeof(*ocxlpmem), GFP_KERNEL);
+	if (!ocxlpmem) {
+		rc = -ENOMEM;
+		goto err;
+	}
+
+	ocxlpmem->pdev = pci_dev_get(pdev);
+
+	pci_set_drvdata(pdev, ocxlpmem);
+
+	ocxlpmem->ocxl_fn = ocxl_function_open(pdev);
+	if (IS_ERR(ocxlpmem->ocxl_fn)) {
+		rc = PTR_ERR(ocxlpmem->ocxl_fn);
+		dev_err(&pdev->dev, "failed to open OCXL function\n");
+		goto err_unregistered;
+	}
+
+	ocxlpmem->ocxl_afu = ocxl_function_fetch_afu(ocxlpmem->ocxl_fn, 0);
+	if (!ocxlpmem->ocxl_afu) {
+		rc = -ENXIO;
+		dev_err(&pdev->dev, "Could not get OCXL AFU from function\n");
+		goto err_unregistered;
+	}
+
+	ocxl_afu_get(ocxlpmem->ocxl_afu);
+
+	// Resources allocated below here are cleaned up in the release handler
+
+	rc = ocxlpmem_register(ocxlpmem);
+	if (rc) {
+		dev_err(&pdev->dev,
+			"Could not register OpenCAPI persistent memory device with the kernel\n");
+		goto err;
+	}
+
+	rc = ocxl_context_alloc(&ocxlpmem->ocxl_context, ocxlpmem->ocxl_afu,
+				NULL);
+	if (rc) {
+		dev_err(&pdev->dev, "Could not allocate OCXL context\n");
+		goto err;
+	}
+
+	rc = ocxl_context_attach(ocxlpmem->ocxl_context, 0, NULL);
+	if (rc) {
+		dev_err(&pdev->dev, "Could not attach ocxl context\n");
+		goto err;
+	}
+
+	rc = register_lpc_mem(ocxlpmem);
+	if (rc) {
+		dev_err(&pdev->dev,
+			"Could not register OpenCAPI persistent memory with libnvdimm\n");
+		goto err;
+	}
+
+	return 0;
+
+err_unregistered:
+	if (!IS_ERR(ocxlpmem->ocxl_fn))
+		ocxl_function_close(ocxlpmem->ocxl_fn);
+	pci_dev_put(ocxlpmem->pdev);
+	kfree(ocxlpmem);
+	pci_set_drvdata(pdev, NULL);
+
+err:
+	/*
+	 * Further cleanup is done in the release handler via free_ocxlpmem()
+	 * This allows us to keep the character device live to handle IOCTLs to
+	 * investigate issues if the card has an error
+	 */
+
+	dev_err(&pdev->dev,
+		"Error detected, will not register OpenCAPI persistent memory\n");
+	return 0;
+}
+
+static struct pci_driver pci_driver = {
+	.name = "ocxlpmem",
+	.id_table = pci_tbl,
+	.probe = probe,
+	.remove = remove,
+	.shutdown = remove,
+};
+
+static int __init ocxlpmem_init(void)
+{
+	int rc;
+
+	mutex_init(&minors_idr_lock);
+	idr_init(&minors_idr);
+
+	rc = pci_register_driver(&pci_driver);
+	if (rc)
+		return rc;
+
+	return 0;
+}
+
+static void ocxlpmem_exit(void)
+{
+	pci_unregister_driver(&pci_driver);
+}
+
+module_init(ocxlpmem_init);
+module_exit(ocxlpmem_exit);
+
+MODULE_DESCRIPTION("OpenCAPI Persistent Memory");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Alastair D'Silva <alastair@d-silva.org>");
diff --git a/drivers/nvdimm/ocxl/ocxlpmem.h b/drivers/nvdimm/ocxl/ocxlpmem.h
new file mode 100644
index 000000000000..03fe7a264281
--- /dev/null
+++ b/drivers/nvdimm/ocxl/ocxlpmem.h
@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0+
+// Copyright 2020 IBM Corp.
+
+#include <linux/pci.h>
+#include <misc/ocxl.h>
+#include <linux/libnvdimm.h>
+#include <linux/mm.h>
+
+#define LABEL_AREA_SIZE	BIT_ULL(PA_SECTION_SHIFT)
+
+struct ocxlpmem {
+	struct device dev;
+	struct pci_dev *pdev;
+	struct ocxl_fn *ocxl_fn;
+	struct nd_interleave_set nd_set;
+	struct nvdimm_bus_descriptor bus_desc;
+	struct nvdimm_bus *nvdimm_bus;
+	struct ocxl_afu *ocxl_afu;
+	struct ocxl_context *ocxl_context;
+	void *metadata_addr;
+	struct resource pmem_res;
+	struct nd_region *nd_region;
+};
-- 
2.24.1
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