arch/powerpc/platforms/pseries/papr_scm.c - linux/torvalds/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0

 #define pr_fmt(fmt)	"papr-scm: " fmt

 #include <linux/of.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/ioport.h>
 #include <linux/slab.h>
 #include <linux/ndctl.h>
 #include <linux/sched.h>
 #include <linux/libnvdimm.h>
 #include <linux/platform_device.h>
 #include <linux/delay.h>

 #include <asm/plpar_wrappers.h>

 #define BIND_ANY_ADDR (~0ul)

 #define PAPR_SCM_DIMM_CMD_MASK \
 	((1ul << ND_CMD_GET_CONFIG_SIZE) | \
 	 (1ul << ND_CMD_GET_CONFIG_DATA) | \
 	 (1ul << ND_CMD_SET_CONFIG_DATA))

 struct papr_scm_priv {
 	struct platform_device *pdev;
 	struct device_node *dn;
 	uint32_t drc_index;
 	uint64_t blocks;
 	uint64_t block_size;
 	int metadata_size;
 	bool is_volatile;

 	uint64_t bound_addr;

 	struct nvdimm_bus_descriptor bus_desc;
 	struct nvdimm_bus *bus;
 	struct nvdimm *nvdimm;
 	struct resource res;
 	struct nd_region *region;
 	struct nd_interleave_set nd_set;
 };

 static int drc_pmem_bind(struct papr_scm_priv *p)
 {
 	unsigned long ret[PLPAR_HCALL_BUFSIZE];
 	uint64_t saved = 0;
 	uint64_t token;
 	int64_t rc;

 	/*
 	 * When the hypervisor cannot map all the requested memory in a single
 	 * hcall it returns H_BUSY and we call again with the token until
 	 * we get H_SUCCESS. Aborting the retry loop before getting H_SUCCESS
 	 * leave the system in an undefined state, so we wait.
 	 */
 	token = 0;

 	do {
 		rc = plpar_hcall(H_SCM_BIND_MEM, ret, p->drc_index, 0,
 				p->blocks, BIND_ANY_ADDR, token);
 		token = ret[0];
 		if (!saved)
 			saved = ret[1];
 		cond_resched();
 	} while (rc == H_BUSY);

 	if (rc)
 		return rc;

 	p->bound_addr = saved;
 	dev_dbg(&p->pdev->dev, "bound drc 0x%x to %pR\n", p->drc_index, &p->res);
 	return rc;
 }

 static void drc_pmem_unbind(struct papr_scm_priv *p)
 {
 	unsigned long ret[PLPAR_HCALL_BUFSIZE];
 	uint64_t token = 0;
 	int64_t rc;

 	dev_dbg(&p->pdev->dev, "unbind drc 0x%x\n", p->drc_index);

 	/* NB: unbind has the same retry requirements as drc_pmem_bind() */
 	do {

 		/* Unbind of all SCM resources associated with drcIndex */
 		rc = plpar_hcall(H_SCM_UNBIND_ALL, ret, H_UNBIND_SCOPE_DRC,
 				 p->drc_index, token);
 		token = ret[0];

 		/* Check if we are stalled for some time */
 		if (H_IS_LONG_BUSY(rc)) {
 			msleep(get_longbusy_msecs(rc));
 			rc = H_BUSY;
 		} else if (rc == H_BUSY) {
 			cond_resched();
 		}

 	} while (rc == H_BUSY);

 	if (rc)
 		dev_err(&p->pdev->dev, "unbind error: %lld\n", rc);
 	else
 		dev_dbg(&p->pdev->dev, "unbind drc 0x%x complete\n",
 			p->drc_index);

 	return;
 }

 static int drc_pmem_query_n_bind(struct papr_scm_priv *p)
 {
 	unsigned long start_addr;
 	unsigned long end_addr;
 	unsigned long ret[PLPAR_HCALL_BUFSIZE];
 	int64_t rc;


 	rc = plpar_hcall(H_SCM_QUERY_BLOCK_MEM_BINDING, ret,
 			 p->drc_index, 0);
 	if (rc)
 		goto err_out;
 	start_addr = ret[0];

 	/* Make sure the full region is bound. */
 	rc = plpar_hcall(H_SCM_QUERY_BLOCK_MEM_BINDING, ret,
 			 p->drc_index, p->blocks - 1);
 	if (rc)
 		goto err_out;
 	end_addr = ret[0];

 	if ((end_addr - start_addr) != ((p->blocks - 1) * p->block_size))
 		goto err_out;

 	p->bound_addr = start_addr;
 	dev_dbg(&p->pdev->dev, "bound drc 0x%x to %pR\n", p->drc_index, &p->res);
 	return rc;

 err_out:
 	dev_info(&p->pdev->dev,
 		 "Failed to query, trying an unbind followed by bind");
 	drc_pmem_unbind(p);
 	return drc_pmem_bind(p);
 }


 static int papr_scm_meta_get(struct papr_scm_priv *p,
 			     struct nd_cmd_get_config_data_hdr *hdr)
 {
 	unsigned long data[PLPAR_HCALL_BUFSIZE];
 	unsigned long offset, data_offset;
 	int len, read;
 	int64_t ret;

 	if ((hdr->in_offset + hdr->in_length) > p->metadata_size)
 		return -EINVAL;

 	for (len = hdr->in_length; len; len -= read) {

 		data_offset = hdr->in_length - len;
 		offset = hdr->in_offset + data_offset;

 		if (len >= 8)
 			read = 8;
 		else if (len >= 4)
 			read = 4;
 		else if (len >= 2)
 			read = 2;
 		else
 			read = 1;

 		ret = plpar_hcall(H_SCM_READ_METADATA, data, p->drc_index,
 				  offset, read);

 		if (ret == H_PARAMETER) /* bad DRC index */
 			return -ENODEV;
 		if (ret)
 			return -EINVAL; /* other invalid parameter */

 		switch (read) {
 		case 8:
 			*(uint64_t *)(hdr->out_buf + data_offset) = be64_to_cpu(data[0]);
 			break;
 		case 4:
 			*(uint32_t *)(hdr->out_buf + data_offset) = be32_to_cpu(data[0] & 0xffffffff);
 			break;

 		case 2:
 			*(uint16_t *)(hdr->out_buf + data_offset) = be16_to_cpu(data[0] & 0xffff);
 			break;

 		case 1:
 			*(uint8_t *)(hdr->out_buf + data_offset) = (data[0] & 0xff);
 			break;
 		}
 	}
 	return 0;
 }

 static int papr_scm_meta_set(struct papr_scm_priv *p,
 			     struct nd_cmd_set_config_hdr *hdr)
 {
 	unsigned long offset, data_offset;
 	int len, wrote;
 	unsigned long data;
 	__be64 data_be;
 	int64_t ret;

 	if ((hdr->in_offset + hdr->in_length) > p->metadata_size)
 		return -EINVAL;

 	for (len = hdr->in_length; len; len -= wrote) {

 		data_offset = hdr->in_length - len;
 		offset = hdr->in_offset + data_offset;

 		if (len >= 8) {
 			data = *(uint64_t *)(hdr->in_buf + data_offset);
 			data_be = cpu_to_be64(data);
 			wrote = 8;
 		} else if (len >= 4) {
 			data = *(uint32_t *)(hdr->in_buf + data_offset);
 			data &= 0xffffffff;
 			data_be = cpu_to_be32(data);
 			wrote = 4;
 		} else if (len >= 2) {
 			data = *(uint16_t *)(hdr->in_buf + data_offset);
 			data &= 0xffff;
 			data_be = cpu_to_be16(data);
 			wrote = 2;
 		} else {
 			data_be = *(uint8_t *)(hdr->in_buf + data_offset);
 			data_be &= 0xff;
 			wrote = 1;
 		}

 		ret = plpar_hcall_norets(H_SCM_WRITE_METADATA, p->drc_index,
 					 offset, data_be, wrote);
 		if (ret == H_PARAMETER) /* bad DRC index */
 			return -ENODEV;
 		if (ret)
 			return -EINVAL; /* other invalid parameter */
 	}

 	return 0;
 }

 int papr_scm_ndctl(struct nvdimm_bus_descriptor *nd_desc, struct nvdimm *nvdimm,
 		unsigned int cmd, void *buf, unsigned int buf_len, int *cmd_rc)
 {
 	struct nd_cmd_get_config_size *get_size_hdr;
 	struct papr_scm_priv *p;

 	/* Only dimm-specific calls are supported atm */
 	if (!nvdimm)
 		return -EINVAL;

 	p = nvdimm_provider_data(nvdimm);

 	switch (cmd) {
 	case ND_CMD_GET_CONFIG_SIZE:
 		get_size_hdr = buf;

 		get_size_hdr->status = 0;
 		get_size_hdr->max_xfer = 8;
 		get_size_hdr->config_size = p->metadata_size;
 		*cmd_rc = 0;
 		break;

 	case ND_CMD_GET_CONFIG_DATA:
 		*cmd_rc = papr_scm_meta_get(p, buf);
 		break;

 	case ND_CMD_SET_CONFIG_DATA:
 		*cmd_rc = papr_scm_meta_set(p, buf);
 		break;

 	default:
 		return -EINVAL;
 	}

 	dev_dbg(&p->pdev->dev, "returned with cmd_rc = %d\n", *cmd_rc);

 	return 0;
 }

 static inline int papr_scm_node(int node)
 {
 	int min_dist = INT_MAX, dist;
 	int nid, min_node;

 	if ((node == NUMA_NO_NODE) || node_online(node))
 		return node;

 	min_node = first_online_node;
 	for_each_online_node(nid) {
 		dist = node_distance(node, nid);
 		if (dist < min_dist) {
 			min_dist = dist;
 			min_node = nid;
 		}
 	}
 	return min_node;
 }

 static int papr_scm_nvdimm_init(struct papr_scm_priv *p)
 {
 	struct device *dev = &p->pdev->dev;
 	struct nd_mapping_desc mapping;
 	struct nd_region_desc ndr_desc;
 	unsigned long dimm_flags;
 	int target_nid, online_nid;

 	p->bus_desc.ndctl = papr_scm_ndctl;
 	p->bus_desc.module = THIS_MODULE;
 	p->bus_desc.of_node = p->pdev->dev.of_node;
 	p->bus_desc.provider_name = kstrdup(p->pdev->name, GFP_KERNEL);

 	if (!p->bus_desc.provider_name)
 		return -ENOMEM;

 	p->bus = nvdimm_bus_register(NULL, &p->bus_desc);
 	if (!p->bus) {
 		dev_err(dev, "Error creating nvdimm bus %pOF\n", p->dn);
 		return -ENXIO;
 	}

 	dimm_flags = 0;
 	set_bit(NDD_ALIASING, &dimm_flags);

 	p->nvdimm = nvdimm_create(p->bus, p, NULL, dimm_flags,
 				  PAPR_SCM_DIMM_CMD_MASK, 0, NULL);
 	if (!p->nvdimm) {
 		dev_err(dev, "Error creating DIMM object for %pOF\n", p->dn);
 		goto err;
 	}

 	if (nvdimm_bus_check_dimm_count(p->bus, 1))
 		goto err;

 	/* now add the region */

 	memset(&mapping, 0, sizeof(mapping));
 	mapping.nvdimm = p->nvdimm;
 	mapping.start = 0;
 	mapping.size = p->blocks * p->block_size; // XXX: potential overflow?

 	memset(&ndr_desc, 0, sizeof(ndr_desc));
 	target_nid = dev_to_node(&p->pdev->dev);
 	online_nid = papr_scm_node(target_nid);
 	ndr_desc.numa_node = online_nid;
 	ndr_desc.target_node = target_nid;
 	ndr_desc.res = &p->res;
 	ndr_desc.of_node = p->dn;
 	ndr_desc.provider_data = p;
 	ndr_desc.mapping = &mapping;
 	ndr_desc.num_mappings = 1;
 	ndr_desc.nd_set = &p->nd_set;
 	set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags);

 	if (p->is_volatile)
 		p->region = nvdimm_volatile_region_create(p->bus, &ndr_desc);
 	else
 		p->region = nvdimm_pmem_region_create(p->bus, &ndr_desc);
 	if (!p->region) {
 		dev_err(dev, "Error registering region %pR from %pOF\n",
 				ndr_desc.res, p->dn);
 		goto err;
 	}
 	if (target_nid != online_nid)
 		dev_info(dev, "Region registered with target node %d and online node %d",
 			 target_nid, online_nid);

 	return 0;

 err:	nvdimm_bus_unregister(p->bus);
 	kfree(p->bus_desc.provider_name);
 	return -ENXIO;
 }

 static int papr_scm_probe(struct platform_device *pdev)
 {
 	struct device_node *dn = pdev->dev.of_node;
 	u32 drc_index, metadata_size;
 	u64 blocks, block_size;
 	struct papr_scm_priv *p;
 	const char *uuid_str;
 	u64 uuid[2];
 	int rc;

 	/* check we have all the required DT properties */
 	if (of_property_read_u32(dn, "ibm,my-drc-index", &drc_index)) {
 		dev_err(&pdev->dev, "%pOF: missing drc-index!\n", dn);
 		return -ENODEV;
 	}

 	if (of_property_read_u64(dn, "ibm,block-size", &block_size)) {
 		dev_err(&pdev->dev, "%pOF: missing block-size!\n", dn);
 		return -ENODEV;
 	}

 	if (of_property_read_u64(dn, "ibm,number-of-blocks", &blocks)) {
 		dev_err(&pdev->dev, "%pOF: missing number-of-blocks!\n", dn);
 		return -ENODEV;
 	}

 	if (of_property_read_string(dn, "ibm,unit-guid", &uuid_str)) {
 		dev_err(&pdev->dev, "%pOF: missing unit-guid!\n", dn);
 		return -ENODEV;
 	}


 	p = kzalloc(sizeof(*p), GFP_KERNEL);
 	if (!p)
 		return -ENOMEM;

 	/* optional DT properties */
 	of_property_read_u32(dn, "ibm,metadata-size", &metadata_size);

 	p->dn = dn;
 	p->drc_index = drc_index;
 	p->block_size = block_size;
 	p->blocks = blocks;
 	p->is_volatile = !of_property_read_bool(dn, "ibm,cache-flush-required");

 	/* We just need to ensure that set cookies are unique across */
 	uuid_parse(uuid_str, (uuid_t *) uuid);
 	/*
 	 * cookie1 and cookie2 are not really little endian
 	 * we store a little endian representation of the
 	 * uuid str so that we can compare this with the label
 	 * area cookie irrespective of the endian config with which
 	 * the kernel is built.
 	 */
 	p->nd_set.cookie1 = cpu_to_le64(uuid[0]);
 	p->nd_set.cookie2 = cpu_to_le64(uuid[1]);

 	/* might be zero */
 	p->metadata_size = metadata_size;
 	p->pdev = pdev;

 	/* request the hypervisor to bind this region to somewhere in memory */
 	rc = drc_pmem_bind(p);

 	/* If phyp says drc memory still bound then force unbound and retry */
 	if (rc == H_OVERLAP)
 		rc = drc_pmem_query_n_bind(p);

 	if (rc != H_SUCCESS) {
 		dev_err(&p->pdev->dev, "bind err: %d\n", rc);
 		rc = -ENXIO;
 		goto err;
 	}

 	/* setup the resource for the newly bound range */
 	p->res.start = p->bound_addr;
 	p->res.end   = p->bound_addr + p->blocks * p->block_size - 1;
 	p->res.name  = pdev->name;
 	p->res.flags = IORESOURCE_MEM;

 	rc = papr_scm_nvdimm_init(p);
 	if (rc)
 		goto err2;

 	platform_set_drvdata(pdev, p);

 	return 0;

 err2:	drc_pmem_unbind(p);
 err:	kfree(p);
 	return rc;
 }

 static int papr_scm_remove(struct platform_device *pdev)
 {
 	struct papr_scm_priv *p = platform_get_drvdata(pdev);

 	nvdimm_bus_unregister(p->bus);
 	drc_pmem_unbind(p);
 	kfree(p);

 	return 0;
 }

 static const struct of_device_id papr_scm_match[] = {
 	{ .compatible = "ibm,pmemory" },
 	{ },
 };

 static struct platform_driver papr_scm_driver = {
 	.probe = papr_scm_probe,
 	.remove = papr_scm_remove,
 	.driver = {
 		.name = "papr_scm",
 		.of_match_table = papr_scm_match,
 	},
 };

 module_platform_driver(papr_scm_driver);
 MODULE_DEVICE_TABLE(of, papr_scm_match);
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("IBM Corporation");
	// SPDX-License-Identifier: GPL-2.0

	#define pr_fmt(fmt) "papr-scm: " fmt

	#include <linux/of.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/ioport.h>
	#include <linux/slab.h>
	#include <linux/ndctl.h>
	#include <linux/sched.h>
	#include <linux/libnvdimm.h>
	#include <linux/platform_device.h>
	#include <linux/delay.h>

	#include <asm/plpar_wrappers.h>

	#define BIND_ANY_ADDR (~0ul)

	#define PAPR_SCM_DIMM_CMD_MASK \
	((1ul << ND_CMD_GET_CONFIG_SIZE) \| \
	(1ul << ND_CMD_GET_CONFIG_DATA) \| \
	(1ul << ND_CMD_SET_CONFIG_DATA))

	struct papr_scm_priv {
	struct platform_device *pdev;
	struct device_node *dn;
	uint32_t drc_index;
	uint64_t blocks;
	uint64_t block_size;
	int metadata_size;
	bool is_volatile;

	uint64_t bound_addr;

	struct nvdimm_bus_descriptor bus_desc;
	struct nvdimm_bus *bus;
	struct nvdimm *nvdimm;
	struct resource res;
	struct nd_region *region;
	struct nd_interleave_set nd_set;
	};

	static int drc_pmem_bind(struct papr_scm_priv *p)
	{
	unsigned long ret[PLPAR_HCALL_BUFSIZE];
	uint64_t saved = 0;
	uint64_t token;
	int64_t rc;

	/*
	* When the hypervisor cannot map all the requested memory in a single
	* hcall it returns H_BUSY and we call again with the token until
	* we get H_SUCCESS. Aborting the retry loop before getting H_SUCCESS
	* leave the system in an undefined state, so we wait.
	*/
	token = 0;

	do {
	rc = plpar_hcall(H_SCM_BIND_MEM, ret, p->drc_index, 0,
	p->blocks, BIND_ANY_ADDR, token);
	token = ret[0];
	if (!saved)
	saved = ret[1];
	cond_resched();
	} while (rc == H_BUSY);

	if (rc)
	return rc;

	p->bound_addr = saved;
	dev_dbg(&p->pdev->dev, "bound drc 0x%x to %pR\n", p->drc_index, &p->res);
	return rc;
	}

	static void drc_pmem_unbind(struct papr_scm_priv *p)
	{
	unsigned long ret[PLPAR_HCALL_BUFSIZE];
	uint64_t token = 0;
	int64_t rc;

	dev_dbg(&p->pdev->dev, "unbind drc 0x%x\n", p->drc_index);

	/* NB: unbind has the same retry requirements as drc_pmem_bind() */
	do {

	/* Unbind of all SCM resources associated with drcIndex */
	rc = plpar_hcall(H_SCM_UNBIND_ALL, ret, H_UNBIND_SCOPE_DRC,
	p->drc_index, token);
	token = ret[0];

	/* Check if we are stalled for some time */
	if (H_IS_LONG_BUSY(rc)) {
	msleep(get_longbusy_msecs(rc));
	rc = H_BUSY;
	} else if (rc == H_BUSY) {
	cond_resched();
	}

	} while (rc == H_BUSY);

	if (rc)
	dev_err(&p->pdev->dev, "unbind error: %lld\n", rc);
	else
	dev_dbg(&p->pdev->dev, "unbind drc 0x%x complete\n",
	p->drc_index);

	return;
	}

	static int drc_pmem_query_n_bind(struct papr_scm_priv *p)
	{
	unsigned long start_addr;
	unsigned long end_addr;
	unsigned long ret[PLPAR_HCALL_BUFSIZE];
	int64_t rc;


	rc = plpar_hcall(H_SCM_QUERY_BLOCK_MEM_BINDING, ret,
	p->drc_index, 0);
	if (rc)
	goto err_out;
	start_addr = ret[0];

	/* Make sure the full region is bound. */
	rc = plpar_hcall(H_SCM_QUERY_BLOCK_MEM_BINDING, ret,
	p->drc_index, p->blocks - 1);
	if (rc)
	goto err_out;
	end_addr = ret[0];

	if ((end_addr - start_addr) != ((p->blocks - 1) * p->block_size))
	goto err_out;

	p->bound_addr = start_addr;
	dev_dbg(&p->pdev->dev, "bound drc 0x%x to %pR\n", p->drc_index, &p->res);
	return rc;

	err_out:
	dev_info(&p->pdev->dev,
	"Failed to query, trying an unbind followed by bind");
	drc_pmem_unbind(p);
	return drc_pmem_bind(p);
	}


	static int papr_scm_meta_get(struct papr_scm_priv *p,
	struct nd_cmd_get_config_data_hdr *hdr)
	{
	unsigned long data[PLPAR_HCALL_BUFSIZE];
	unsigned long offset, data_offset;
	int len, read;
	int64_t ret;

	if ((hdr->in_offset + hdr->in_length) > p->metadata_size)
	return -EINVAL;

	for (len = hdr->in_length; len; len -= read) {

	data_offset = hdr->in_length - len;
	offset = hdr->in_offset + data_offset;

	if (len >= 8)
	read = 8;
	else if (len >= 4)
	read = 4;
	else if (len >= 2)
	read = 2;
	else
	read = 1;

	ret = plpar_hcall(H_SCM_READ_METADATA, data, p->drc_index,
	offset, read);

	if (ret == H_PARAMETER) /* bad DRC index */
	return -ENODEV;
	if (ret)
	return -EINVAL; /* other invalid parameter */

	switch (read) {
	case 8:
	(uint64_t )(hdr->out_buf + data_offset) = be64_to_cpu(data[0]);
	break;
	case 4:
	(uint32_t )(hdr->out_buf + data_offset) = be32_to_cpu(data[0] & 0xffffffff);
	break;

	case 2:
	(uint16_t )(hdr->out_buf + data_offset) = be16_to_cpu(data[0] & 0xffff);
	break;

	case 1:
	(uint8_t )(hdr->out_buf + data_offset) = (data[0] & 0xff);
	break;
	}
	}
	return 0;
	}

	static int papr_scm_meta_set(struct papr_scm_priv *p,
	struct nd_cmd_set_config_hdr *hdr)
	{
	unsigned long offset, data_offset;
	int len, wrote;
	unsigned long data;
	__be64 data_be;
	int64_t ret;

	if ((hdr->in_offset + hdr->in_length) > p->metadata_size)
	return -EINVAL;

	for (len = hdr->in_length; len; len -= wrote) {

	data_offset = hdr->in_length - len;
	offset = hdr->in_offset + data_offset;

	if (len >= 8) {
	data = (uint64_t )(hdr->in_buf + data_offset);
	data_be = cpu_to_be64(data);
	wrote = 8;
	} else if (len >= 4) {
	data = (uint32_t )(hdr->in_buf + data_offset);
	data &= 0xffffffff;
	data_be = cpu_to_be32(data);
	wrote = 4;
	} else if (len >= 2) {
	data = (uint16_t )(hdr->in_buf + data_offset);
	data &= 0xffff;
	data_be = cpu_to_be16(data);
	wrote = 2;
	} else {
	data_be = (uint8_t )(hdr->in_buf + data_offset);
	data_be &= 0xff;
	wrote = 1;
	}

	ret = plpar_hcall_norets(H_SCM_WRITE_METADATA, p->drc_index,
	offset, data_be, wrote);
	if (ret == H_PARAMETER) /* bad DRC index */
	return -ENODEV;
	if (ret)
	return -EINVAL; /* other invalid parameter */
	}

	return 0;
	}

	int papr_scm_ndctl(struct nvdimm_bus_descriptor nd_desc, struct nvdimm nvdimm,
	unsigned int cmd, void buf, unsigned int buf_len, int cmd_rc)
	{
	struct nd_cmd_get_config_size *get_size_hdr;
	struct papr_scm_priv *p;

	/* Only dimm-specific calls are supported atm */
	if (!nvdimm)
	return -EINVAL;

	p = nvdimm_provider_data(nvdimm);

	switch (cmd) {
	case ND_CMD_GET_CONFIG_SIZE:
	get_size_hdr = buf;

	get_size_hdr->status = 0;
	get_size_hdr->max_xfer = 8;
	get_size_hdr->config_size = p->metadata_size;
	*cmd_rc = 0;
	break;

	case ND_CMD_GET_CONFIG_DATA:
	*cmd_rc = papr_scm_meta_get(p, buf);
	break;

	case ND_CMD_SET_CONFIG_DATA:
	*cmd_rc = papr_scm_meta_set(p, buf);
	break;

	default:
	return -EINVAL;
	}

	dev_dbg(&p->pdev->dev, "returned with cmd_rc = %d\n", *cmd_rc);

	return 0;
	}

	static inline int papr_scm_node(int node)
	{
	int min_dist = INT_MAX, dist;
	int nid, min_node;

	if ((node == NUMA_NO_NODE) \|\| node_online(node))
	return node;

	min_node = first_online_node;
	for_each_online_node(nid) {
	dist = node_distance(node, nid);
	if (dist < min_dist) {
	min_dist = dist;
	min_node = nid;
	}
	}
	return min_node;
	}

	static int papr_scm_nvdimm_init(struct papr_scm_priv *p)
	{
	struct device *dev = &p->pdev->dev;
	struct nd_mapping_desc mapping;
	struct nd_region_desc ndr_desc;
	unsigned long dimm_flags;
	int target_nid, online_nid;

	p->bus_desc.ndctl = papr_scm_ndctl;
	p->bus_desc.module = THIS_MODULE;
	p->bus_desc.of_node = p->pdev->dev.of_node;
	p->bus_desc.provider_name = kstrdup(p->pdev->name, GFP_KERNEL);

	if (!p->bus_desc.provider_name)
	return -ENOMEM;

	p->bus = nvdimm_bus_register(NULL, &p->bus_desc);
	if (!p->bus) {
	dev_err(dev, "Error creating nvdimm bus %pOF\n", p->dn);
	return -ENXIO;
	}

	dimm_flags = 0;
	set_bit(NDD_ALIASING, &dimm_flags);

	p->nvdimm = nvdimm_create(p->bus, p, NULL, dimm_flags,
	PAPR_SCM_DIMM_CMD_MASK, 0, NULL);
	if (!p->nvdimm) {
	dev_err(dev, "Error creating DIMM object for %pOF\n", p->dn);
	goto err;
	}

	if (nvdimm_bus_check_dimm_count(p->bus, 1))
	goto err;

	/* now add the region */

	memset(&mapping, 0, sizeof(mapping));
	mapping.nvdimm = p->nvdimm;
	mapping.start = 0;
	mapping.size = p->blocks * p->block_size; // XXX: potential overflow?

	memset(&ndr_desc, 0, sizeof(ndr_desc));
	target_nid = dev_to_node(&p->pdev->dev);
	online_nid = papr_scm_node(target_nid);
	ndr_desc.numa_node = online_nid;
	ndr_desc.target_node = target_nid;
	ndr_desc.res = &p->res;
	ndr_desc.of_node = p->dn;
	ndr_desc.provider_data = p;
	ndr_desc.mapping = &mapping;
	ndr_desc.num_mappings = 1;
	ndr_desc.nd_set = &p->nd_set;
	set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags);

	if (p->is_volatile)
	p->region = nvdimm_volatile_region_create(p->bus, &ndr_desc);
	else
	p->region = nvdimm_pmem_region_create(p->bus, &ndr_desc);
	if (!p->region) {
	dev_err(dev, "Error registering region %pR from %pOF\n",
	ndr_desc.res, p->dn);
	goto err;
	}
	if (target_nid != online_nid)
	dev_info(dev, "Region registered with target node %d and online node %d",
	target_nid, online_nid);

	return 0;

	err: nvdimm_bus_unregister(p->bus);
	kfree(p->bus_desc.provider_name);
	return -ENXIO;
	}

	static int papr_scm_probe(struct platform_device *pdev)
	{
	struct device_node *dn = pdev->dev.of_node;
	u32 drc_index, metadata_size;
	u64 blocks, block_size;
	struct papr_scm_priv *p;
	const char *uuid_str;
	u64 uuid[2];
	int rc;

	/* check we have all the required DT properties */
	if (of_property_read_u32(dn, "ibm,my-drc-index", &drc_index)) {
	dev_err(&pdev->dev, "%pOF: missing drc-index!\n", dn);
	return -ENODEV;
	}

	if (of_property_read_u64(dn, "ibm,block-size", &block_size)) {
	dev_err(&pdev->dev, "%pOF: missing block-size!\n", dn);
	return -ENODEV;
	}

	if (of_property_read_u64(dn, "ibm,number-of-blocks", &blocks)) {
	dev_err(&pdev->dev, "%pOF: missing number-of-blocks!\n", dn);
	return -ENODEV;
	}

	if (of_property_read_string(dn, "ibm,unit-guid", &uuid_str)) {
	dev_err(&pdev->dev, "%pOF: missing unit-guid!\n", dn);
	return -ENODEV;
	}


	p = kzalloc(sizeof(*p), GFP_KERNEL);
	if (!p)
	return -ENOMEM;

	/* optional DT properties */
	of_property_read_u32(dn, "ibm,metadata-size", &metadata_size);

	p->dn = dn;
	p->drc_index = drc_index;
	p->block_size = block_size;
	p->blocks = blocks;
	p->is_volatile = !of_property_read_bool(dn, "ibm,cache-flush-required");

	/* We just need to ensure that set cookies are unique across */
	uuid_parse(uuid_str, (uuid_t *) uuid);
	/*
	* cookie1 and cookie2 are not really little endian
	* we store a little endian representation of the
	* uuid str so that we can compare this with the label
	* area cookie irrespective of the endian config with which
	* the kernel is built.
	*/
	p->nd_set.cookie1 = cpu_to_le64(uuid[0]);
	p->nd_set.cookie2 = cpu_to_le64(uuid[1]);

	/* might be zero */
	p->metadata_size = metadata_size;
	p->pdev = pdev;

	/* request the hypervisor to bind this region to somewhere in memory */
	rc = drc_pmem_bind(p);

	/* If phyp says drc memory still bound then force unbound and retry */
	if (rc == H_OVERLAP)
	rc = drc_pmem_query_n_bind(p);

	if (rc != H_SUCCESS) {
	dev_err(&p->pdev->dev, "bind err: %d\n", rc);
	rc = -ENXIO;
	goto err;
	}

	/* setup the resource for the newly bound range */
	p->res.start = p->bound_addr;
	p->res.end = p->bound_addr + p->blocks * p->block_size - 1;
	p->res.name = pdev->name;
	p->res.flags = IORESOURCE_MEM;

	rc = papr_scm_nvdimm_init(p);
	if (rc)
	goto err2;

	platform_set_drvdata(pdev, p);

	return 0;

	err2: drc_pmem_unbind(p);
	err: kfree(p);
	return rc;
	}

	static int papr_scm_remove(struct platform_device *pdev)
	{
	struct papr_scm_priv *p = platform_get_drvdata(pdev);

	nvdimm_bus_unregister(p->bus);
	drc_pmem_unbind(p);
	kfree(p);

	return 0;
	}

	static const struct of_device_id papr_scm_match[] = {
	{ .compatible = "ibm,pmemory" },
	{ },
	};

	static struct platform_driver papr_scm_driver = {
	.probe = papr_scm_probe,
	.remove = papr_scm_remove,
	.driver = {
	.name = "papr_scm",
	.of_match_table = papr_scm_match,
	},
	};

	module_platform_driver(papr_scm_driver);
	MODULE_DEVICE_TABLE(of, papr_scm_match);
	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("IBM Corporation");