Commit b5beae5e authored by Oliver O'Halloran's avatar Oliver O'Halloran Committed by Michael Ellerman
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powerpc/pseries: Add driver for PAPR SCM regions

Adds a driver that implements support for enabling and accessing PAPR
SCM regions. Unfortunately due to how the PAPR interface works we can't
use the existing of_pmem driver (yet) because:

 a) The guest is required to use the H_SCM_BIND_MEM h-call to add
    add the SCM region to it's physical address space, and
 b) There is currently no mechanism for relating a bare of_pmem region
    to the backing DIMM (or not-a-DIMM for our case).

Both of these are easily handled by rolling the functionality into a
seperate driver so here we are...

Acked-by: default avatarDan Williams <>
Signed-off-by: default avatarOliver O'Halloran <>
Signed-off-by: default avatarMichael Ellerman <>
parent 4c5d87db
......@@ -138,3 +138,10 @@ config IBMEBUS
bool "Support for GX bus based adapters"
Bus device driver for GX bus based adapters.
config PAPR_SCM
tristate "Support for the PAPR Storage Class Memory interface"
Enable access to hypervisor provided storage class memory.
......@@ -24,6 +24,7 @@ obj-$(CONFIG_IO_EVENT_IRQ) += io_event_irq.o
obj-$(CONFIG_LPARCFG) += lparcfg.o
obj-$(CONFIG_IBMVIO) += vio.o
obj-$(CONFIG_IBMEBUS) += ibmebus.o
obj-$(CONFIG_PAPR_SCM) += papr_scm.o
obj-$(CONFIG_SUSPEND) += suspend.o
// 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 <asm/plpar_wrappers.h>
#define BIND_ANY_ADDR (~0ul)
((1ul << ND_CMD_GET_CONFIG_SIZE) | \
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;
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 rc, token;
* 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 = be64_to_cpu(ret[0]);
} while (rc == H_BUSY);
if (rc) {
dev_err(&p->pdev->dev, "bind err: %lld\n", rc);
return -ENXIO;
p->bound_addr = be64_to_cpu(ret[1]);
dev_dbg(&p->pdev->dev, "bound drc %x to %pR\n", p->drc_index, &p->res);
return 0;
static int drc_pmem_unbind(struct papr_scm_priv *p)
unsigned long ret[PLPAR_HCALL_BUFSIZE];
uint64_t rc, token;
token = 0;
/* NB: unbind has the same retry requirements mentioned above */
do {
rc = plpar_hcall(H_SCM_UNBIND_MEM, ret, p->drc_index,
p->bound_addr, p->blocks, token);
token = be64_to_cpu(ret);
} while (rc == H_BUSY);
if (rc)
dev_err(&p->pdev->dev, "unbind error: %lld\n", rc);
return !!rc;
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];
int64_t ret;
if (hdr->in_offset >= p->metadata_size || hdr->in_length != 1)
return -EINVAL;
ret = plpar_hcall(H_SCM_READ_METADATA, data, p->drc_index,
hdr->in_offset, 1);
if (ret == H_PARAMETER) /* bad DRC index */
return -ENODEV;
if (ret)
return -EINVAL; /* other invalid parameter */
hdr->out_buf[0] = data[0] & 0xff;
return 0;
static int papr_scm_meta_set(struct papr_scm_priv *p,
struct nd_cmd_set_config_hdr *hdr)
int64_t ret;
if (hdr->in_offset >= p->metadata_size || hdr->in_length != 1)
return -EINVAL;
ret = plpar_hcall_norets(H_SCM_WRITE_METADATA,
p->drc_index, hdr->in_offset, hdr->in_buf[0], 1);
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) {
get_size_hdr = buf;
get_size_hdr->status = 0;
get_size_hdr->max_xfer = 1;
get_size_hdr->config_size = p->metadata_size;
*cmd_rc = 0;
*cmd_rc = papr_scm_meta_get(p, buf);
*cmd_rc = papr_scm_meta_set(p, buf);
return -EINVAL;
dev_dbg(&p->pdev->dev, "returned with cmd_rc = %d\n", *cmd_rc);
return 0;
static const struct attribute_group *region_attr_groups[] = {
static const struct attribute_group *bus_attr_groups[] = {
static const struct attribute_group *papr_scm_dimm_groups[] = {
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;
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.attr_groups = bus_attr_groups;
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, papr_scm_dimm_groups,
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;
/* 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));
ndr_desc.attr_groups = region_attr_groups;
ndr_desc.numa_node = dev_to_node(&p->pdev->dev);
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);
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;
return 0;
err: nvdimm_bus_unregister(p->bus);
return -ENXIO;
static int papr_scm_probe(struct platform_device *pdev)
uint32_t drc_index, metadata_size, unit_cap[2];
struct device_node *dn = pdev->dev.of_node;
struct papr_scm_priv *p;
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_u32_array(dn, "ibm,unit-capacity", unit_cap, 2)) {
dev_err(&pdev->dev, "%pOF: missing unit-capacity!\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 = unit_cap[0];
p->blocks = unit_cap[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 (rc)
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;
p-> = 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);
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",
.owner = THIS_MODULE,
.of_match_table = papr_scm_match,
MODULE_DEVICE_TABLE(of, papr_scm_match);
MODULE_AUTHOR("IBM Corporation");
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