Re: [PATCH 08/10] nvdimm: Add driver for OpenCAPI Storage Class Memory

From: Dan Williams <dan.j.williams@intel.com>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Alastair D'Silva <alastair@au1.ibm.com>,
	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
	linux-nvdimm <linux-nvdimm@lists.01.org>
Subject: Re: [PATCH 08/10] nvdimm: Add driver for OpenCAPI Storage Class Memory
Date: Mon, 11 Nov 2019 21:41:53 -0800	[thread overview]
Message-ID: <CAPcyv4hWdszToHwHesP9UtMxBmFdYxU0mtd7BGifFQHbvXbokQ@mail.gmail.com> (raw)
In-Reply-To: <CAPcyv4iaWN9R5u_2OBjqGt7nirxXKVZ=mCZnDkzyc5np8UCe=A@mail.gmail.com>

On Mon, Nov 11, 2019 at 9:37 PM Dan Williams <dan.j.williams@intel.com> wrote:
>
> On Mon, Nov 11, 2019 at 3:34 AM Aneesh Kumar K.V
> <aneesh.kumar@linux.ibm.com> wrote:
> >
> > "Alastair D'Silva" <alastair@au1.ibm.com> writes:
> >
> > > From: Alastair D'Silva <alastair@d-silva.org>
> > >
> > > This driver exposes LPC memory on OpenCAPI SCM cards
> > > as an NVDIMM, allowing the existing nvram infrastructure
> > > to be used.
> > >
> > > Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> > > ---
> > >  drivers/nvdimm/Kconfig             |   17 +
> > >  drivers/nvdimm/Makefile            |    3 +
> > >  drivers/nvdimm/ocxl-scm.c          | 2210 ++++++++++++++++++++++++++++
> > >  drivers/nvdimm/ocxl-scm_internal.c |  232 +++
> > >  drivers/nvdimm/ocxl-scm_internal.h |  331 +++++
> > >  drivers/nvdimm/ocxl-scm_sysfs.c    |  219 +++
> > >  include/uapi/linux/ocxl-scm.h      |  128 ++
> > >  mm/memory_hotplug.c                |    2 +-
> > >  8 files changed, 3141 insertions(+), 1 deletion(-)
> > >  create mode 100644 drivers/nvdimm/ocxl-scm.c
> > >  create mode 100644 drivers/nvdimm/ocxl-scm_internal.c
> > >  create mode 100644 drivers/nvdimm/ocxl-scm_internal.h
> > >  create mode 100644 drivers/nvdimm/ocxl-scm_sysfs.c
> > >  create mode 100644 include/uapi/linux/ocxl-scm.h
> > >
> > > diff --git a/drivers/nvdimm/Kconfig b/drivers/nvdimm/Kconfig
> > > index 36af7af6b7cf..e4f7b6b08efd 100644
> > > --- a/drivers/nvdimm/Kconfig
> > > +++ b/drivers/nvdimm/Kconfig
> > > @@ -130,4 +130,21 @@ config NVDIMM_TEST_BUILD
> > >         core devm_memremap_pages() implementation and other
> > >         infrastructure.
> > >
> > > +config OCXL_SCM
> > > +     tristate "OpenCAPI Storage Class Memory"
> > > +     depends on LIBNVDIMM
> > > +     select ZONE_DEVICE
> > > +     select OCXL
> > > +     help
> > > +       Exposes devices that implement the OpenCAPI Storage Class Memory
> > > +       specification as persistent memory regions.
> > > +
> > > +       Select N if unsure.
> > > +
> > > +config OCXL_SCM_DEBUG
> > > +     bool "OpenCAPI Storage Class Memory debugging"
> > > +     depends on OCXL_SCM
> > > +     help
> > > +       Enables low level IOCTLs for OpenCAPI SCM firmware development
> > > +
> > >  endif
> > > diff --git a/drivers/nvdimm/Makefile b/drivers/nvdimm/Makefile
> > > index 29203f3d3069..43d826397bfc 100644
> > > --- a/drivers/nvdimm/Makefile
> > > +++ b/drivers/nvdimm/Makefile
> > > @@ -6,6 +6,9 @@ obj-$(CONFIG_ND_BLK) += nd_blk.o
> > >  obj-$(CONFIG_X86_PMEM_LEGACY) += nd_e820.o
> > >  obj-$(CONFIG_OF_PMEM) += of_pmem.o
> > >  obj-$(CONFIG_VIRTIO_PMEM) += virtio_pmem.o nd_virtio.o
> > > +obj-$(CONFIG_OCXL_SCM) += ocxlscm.o
> > > +
> > > +ocxlscm-y := ocxl-scm.o ocxl-scm_internal.o ocxl-scm_sysfs.o
> > >
> > >  nd_pmem-y := pmem.o
> > >
> > > diff --git a/drivers/nvdimm/ocxl-scm.c b/drivers/nvdimm/ocxl-scm.c
> > > new file mode 100644
> > > index 000000000000..f4e6cc022de8
> > > --- /dev/null
> > > +++ b/drivers/nvdimm/ocxl-scm.c
> >
> > how about drivers/nvdimm/ocxl/scm.c ? Or may be place the driver as an
> > ocxl driver.
> >
> >
> > > @@ -0,0 +1,2210 @@
> > > +// SPDX-License-Identifier: GPL-2.0+
> > > +// Copyright 2019 IBM Corp.
> > > +
> > > +/*
> > > + * A driver for Storage Class Memory, connected via OpenCAPI
> > > + */
> > > +
> > > +#include <linux/module.h>
> > > +#include <misc/ocxl.h>
> > > +#include <linux/delay.h>
> > > +#include <linux/ndctl.h>
> > > +#include <linux/eventfd.h>
> > > +#include <linux/fs.h>
> > > +#include <linux/mm_types.h>
> > > +#include <linux/memory_hotplug.h>
> > > +#include "ocxl-scm_internal.h"
> > > +
> > > +
> > > +static const struct pci_device_id scm_pci_tbl[] = {
> > > +     { PCI_DEVICE(PCI_VENDOR_ID_IBM, 0x0625), },
> > > +     { }
> > > +};
> > > +
> > > +MODULE_DEVICE_TABLE(pci, scm_pci_tbl);
> > > +
> > > +#define SCM_NUM_MINORS 256 // Total to reserve
> > > +#define SCM_USABLE_TIMEOUT 120 // seconds
> > > +
> > > +static dev_t scm_dev;
> > > +static struct class *scm_class;
> > > +static struct mutex minors_idr_lock;
> > > +static struct idr minors_idr;
> > > +
> > > +static const struct attribute_group *scm_pmem_attribute_groups[] = {
> > > +     &nvdimm_bus_attribute_group,
> > > +     NULL,
> > > +};
> > > +
> > > +static const struct attribute_group *scm_pmem_region_attribute_groups[] = {
> > > +     &nd_region_attribute_group,
> > > +     &nd_device_attribute_group,
> > > +     &nd_mapping_attribute_group,
> > > +     &nd_numa_attribute_group,
> > > +     NULL,
> > > +};
> > > +
> >
> >
> > There is another patch series that is moving this from device driver to
> > nvdimm core.
> >
> > https://lore.kernel.org/linux-mm/157309899529.1582359.15358067933360719580.stgit@dwillia2-desk3.amr.corp.intel.com
> >
> >
> > > +/**
> > > + * scm_ndctl_config_write() - Handle a ND_CMD_SET_CONFIG_DATA command from ndctl
> > > + * @scm_data: the SCM metadata
> > > + * @command: the incoming data to write
> > > + * Return: 0 on success, negative on failure
> > > + */
> > > +static int scm_ndctl_config_write(struct scm_data *scm_data,
> > > +                               struct nd_cmd_set_config_hdr *command)
> > > +{
> > > +     if (command->in_offset + command->in_length > SCM_LABEL_AREA_SIZE)
> > > +             return -EINVAL;
> > > +
> > > +     memcpy_flushcache(scm_data->metadata_addr + command->in_offset, command->in_buf,
> > > +                       command->in_length);
> > > +
> > > +     return 0;
> > > +}
> > > +
> > > +/**
> > > + * scm_ndctl_config_read() - Handle a ND_CMD_GET_CONFIG_DATA command from ndctl
> > > + * @scm_data: the SCM metadata
> > > + * @command: the read request
> > > + * Return: 0 on success, negative on failure
> > > + */
> > > +static int scm_ndctl_config_read(struct scm_data *scm_data,
> > > +                              struct nd_cmd_get_config_data_hdr *command)
> > > +{
> > > +     if (command->in_offset + command->in_length > SCM_LABEL_AREA_SIZE)
> > > +             return -EINVAL;
> > > +
> > > +     memcpy(command->out_buf, scm_data->metadata_addr + command->in_offset,
> > > +            command->in_length);
> > > +
> >
> > memcpy_mcsafe()?
> >
> > > +     return 0;
> > > +}
> > > +
> > > +/**
> > > + * scm_ndctl_config_size() - Handle a ND_CMD_GET_CONFIG_SIZE command from ndctl
> > > + * @scm_data: the SCM metadata
> > > + * @command: the read request
> > > + * Return: 0 on success, negative on failure
> > > + */
> > > +static int scm_ndctl_config_size(struct nd_cmd_get_config_size *command)
> > > +{
> > > +     command->status = 0;
> > > +     command->config_size = SCM_LABEL_AREA_SIZE;
> > > +     command->max_xfer = PAGE_SIZE;
> > > +
> > > +     return 0;
> > > +}
> > > +
> > > +static int read_smart_attrib(struct scm_data *scm_data, u16 offset,
> > > +                          struct scm_smart_attribs *attribs)
> > > +{
> > > +     u64 val;
> > > +     int rc;
> > > +     struct scm_smart_attrib *attrib;
> > > +     u8 attrib_id;
> > > +
> > > +     rc = ocxl_global_mmio_read64(scm_data->ocxl_afu, offset, OCXL_LITTLE_ENDIAN,
> > > +                                  &val);
> > > +     if (rc)
> > > +             return rc;
> > > +
> > > +     attrib_id = (val >> 56) & 0xff;
> > > +     switch (attrib_id) {
> > > +     case SCM_SMART_ATTR_POWER_ON_HOURS:
> > > +             attrib = &attribs->power_on_hours;
> > > +             break;
> > > +
> > > +     case SCM_SMART_ATTR_TEMPERATURE:
> > > +             attrib = &attribs->temperature;
> > > +             break;
> > > +
> > > +     case SCM_SMART_ATTR_LIFE_REMAINING:
> > > +             attrib = &attribs->life_remaining;
> > > +             break;
> > > +
> > > +     default:
> > > +             dev_err(&scm_data->dev, "Unknown smart attrib '%d'", attrib_id);
> > > +             return -EFAULT;
> > > +     }
> > > +
> > > +     attrib->id = attrib_id;
> > > +     attrib->attribute_flags = (val >> 40) & 0xffff;
> > > +     attrib->current_val = (val >> 32) & 0xff;
> > > +     attrib->threshold_val = (val >> 24) & 0xff;
> > > +     attrib->worst_val = (val >> 16) & 0xff;
> > > +
> > > +     rc = ocxl_global_mmio_read64(scm_data->ocxl_afu, offset + 0x08,
> > > +                                  OCXL_LITTLE_ENDIAN, &val);
> > > +     if (rc)
> > > +             return rc;
> > > +
> > > +     attrib->raw_val = val;
> > > +
> > > +     return 0;
> > > +}
> > > +
> > > +static int scm_smart_offset_0x00(struct scm_data *scm_data, u32 *length)
> > > +'
> >
> > What is special about _0x00?
> >
> > {
> > > +     int rc;
> > > +     u64 val;
> > > +
> > > +     u16 data_identifier;
> > > +     u32 data_length;
> > > +
> > > +     rc = ocxl_global_mmio_read64(scm_data->ocxl_afu,
> > > +                                  scm_data->admin_command.data_offset,
> > > +                                  OCXL_LITTLE_ENDIAN, &val);
> > > +     if (rc)
> > > +             return rc;
> > > +
> > > +     data_identifier = val >> 48;
> > > +     data_length = val & 0xFFFFFFFF;
> > > +
> > > +     if (data_identifier != 0x534D) {
> > > +             dev_err(&scm_data->dev,
> > > +                     "Bad data identifier for smart data, expected 'SM', got '%-.*s'\n",
> > > +                     2, (char *)&data_identifier);
> > > +             return -EFAULT;
> > > +     }
> > > +
> > > +     *length = data_length;
> > > +     return 0;
> > > +}
> > > +
> > > +static int scm_smart_update(struct scm_data *scm_data)
> > > +{
> > > +     u32 length, i;
> > > +     int rc;
> > > +
> > > +     mutex_lock(&scm_data->admin_command.lock);
> > > +
> > > +     rc = scm_admin_command_request(scm_data, ADMIN_COMMAND_SMART);
> > > +     if (rc)
> > > +             goto out;
> > > +
> > > +     rc = scm_admin_command_execute(scm_data);
> > > +     if (rc)
> > > +             goto out;
> > > +
> > > +     rc = scm_admin_command_complete_timeout(scm_data, ADMIN_COMMAND_SMART);
> > > +     if (rc < 0) {
> > > +             dev_err(&scm_data->dev, "SMART timeout\n");
> > > +             goto out;
> > > +     }
> > > +
> > > +     rc = scm_admin_response(scm_data);
> > > +     if (rc < 0)
> > > +             goto out;
> > > +     if (rc != STATUS_SUCCESS) {
> > > +             scm_warn_status(scm_data, "Unexpected status from SMART", rc);
> > > +             goto out;
> > > +     }
> > > +
> > > +     rc = scm_smart_offset_0x00(scm_data, &length);
> > > +     if (rc)
> > > +             goto out;
> > > +
> > > +     length /= 0x10; // Length now contains the number of attributes
> > > +
> > > +     for (i = 0; i < length; i++)
> > > +             read_smart_attrib(scm_data,
> > > +                               scm_data->admin_command.data_offset + 0x08 + i * 0x10,
> > > +                               &scm_data->smart);
> > > +
> > > +     rc = scm_admin_response_handled(scm_data);
> > > +     if (rc)
> > > +             goto out;
> > > +
> > > +     rc = 0;
> > > +     goto out;
> > > +
> > > +out:
> > > +     mutex_unlock(&scm_data->admin_command.lock);
> > > +     return rc;
> > > +}
> > > +
> > > +static int scm_ndctl_smart(struct scm_data *scm_data, void *buf,
> > > +                        unsigned int buf_len)
> > > +{
> > > +     int rc;
> > > +
> > > +     if (buf_len != sizeof(scm_data->smart))
> > > +             return -EINVAL;
> > > +
> > > +     rc = scm_smart_update(scm_data);
> > > +     if (rc)
> > > +             return rc;
> > > +
> > > +     memcpy(buf, &scm_data->smart, buf_len);
> > > +
> > > +     return 0;
> > > +}
> > > +
> > > +
> > > +static int scm_ndctl(struct nvdimm_bus_descriptor *nd_desc,
> > > +                  struct nvdimm *nvdimm,
> > > +                  unsigned int cmd, void *buf, unsigned int buf_len, int *cmd_rc)
> > > +{
> > > +     struct scm_data *scm_data = container_of(nd_desc, struct scm_data, bus_desc);
> > > +
> > > +     switch (cmd) {
> > > +     case ND_CMD_SMART:
> > > +             *cmd_rc = scm_ndctl_smart(scm_data, buf, buf_len);
> > > +             return 0;
> > > +
> > > +     case ND_CMD_GET_CONFIG_SIZE:
> > > +             *cmd_rc = scm_ndctl_config_size(buf);
> > > +             return 0;
> > > +
> > > +     case ND_CMD_GET_CONFIG_DATA:
> > > +             *cmd_rc = scm_ndctl_config_read(scm_data, buf);
> > > +             return 0;
> > > +
> > > +     case ND_CMD_SET_CONFIG_DATA:
> > > +             *cmd_rc = scm_ndctl_config_write(scm_data, buf);
> > > +             return 0;
> > > +
> > > +     default:
> > > +             return -ENOTTY;
> > > +     }
> > > +}
> > > +
> > > +static ssize_t serial_show(struct device *dev,
> > > +                        struct device_attribute *attr, char *buf)
> > > +{
> > > +     struct nvdimm *nvdimm = to_nvdimm(dev);
> > > +     struct scm_data *scm_data = nvdimm_provider_data(nvdimm);
> > > +     const struct ocxl_fn_config *config = ocxl_function_config(scm_data->ocxl_fn);
> > > +
> > > +     return sprintf(buf, "0x%llx\n", config->serial);
> > > +}
> > > +static DEVICE_ATTR_RO(serial);
> > > +
> > > +static struct attribute *scm_dimm_attributes[] = {
> > > +     &dev_attr_serial.attr,
> > > +     NULL,
> > > +};
> > > +
> > > +static umode_t scm_dimm_attr_visible(struct kobject *kobj,
> > > +                                  struct attribute *a, int n)
> > > +{
> > > +     return a->mode;
> > > +}
> > > +
> > > +static const struct attribute_group scm_dimm_attribute_group = {
> > > +     .name = "scm",
> > > +     .attrs = scm_dimm_attributes,
> > > +     .is_visible = scm_dimm_attr_visible,
> > > +};
> > > +
> >
> > That is a generic name for dimm attribute
> >
> > > +static const struct attribute_group *scm_dimm_attribute_groups[] = {
> > > +     &nvdimm_attribute_group,
> > > +     &nd_device_attribute_group,
> > > +     &scm_dimm_attribute_group,
> > > +     NULL,
> > > +};
> > > +
> > > +/**
> > > + * scm_reserve_metadata() - Reserve space for nvdimm metadata
> > > + * @scm_data: The SCM device data
> > > + * @lpc_mem: The resource representing the LPC memory of the SCM device
> > > + */
> > > +static int scm_reserve_metadata(struct scm_data *scm_data,
> > > +                             struct resource *lpc_mem)
> > > +{
> > > +     scm_data->metadata_addr = devm_memremap(&scm_data->dev, lpc_mem->start,
> > > +                                             SCM_LABEL_AREA_SIZE, MEMREMAP_WB);
> > > +     if (IS_ERR(scm_data->metadata_addr))
> > > +             return PTR_ERR(scm_data->metadata_addr);
> > > +
> > > +     return 0;
> > > +}
> > > +
> > > +/**
> > > + * scm_overwrite() - Overwrite all data on the card
> > > + * @scm_data: The SCM device data
> > > + * Return: 0 on success
> > > + */
> > > +int scm_overwrite(struct scm_data *scm_data)
> > > +{
> > > +     int rc;
> > > +
> > > +     mutex_lock(&scm_data->ns_command.lock);
> > > +
> > > +     rc = scm_ns_command_request(scm_data, NS_COMMAND_SECURE_ERASE);
> > > +     if (rc)
> > > +             goto out;
> > > +
> > > +     rc = scm_ns_command_execute(scm_data);
> > > +     if (rc)
> > > +             goto out;
> > > +
> > > +     scm_data->overwrite_state = SCM_OVERWRITE_BUSY;
> > > +
> > > +     return 0;
> > > +
> > > +out:
> > > +     mutex_unlock(&scm_data->ns_command.lock);
> > > +     return rc;
> > > +}
> > > +
> > > +/**
> > > + * scm_secop_overwrite() - Overwrite all data on the card
> > > + * @nvdimm: The nvdimm representation of the SCM device to start the overwrite on
> > > + * @key_data: Unused (no security key implementation)
> > > + * Return: 0 on success
> > > + */
> > > +static int scm_secop_overwrite(struct nvdimm *nvdimm,
> > > +                            const struct nvdimm_key_data *key_data)
> > > +{
> > > +     struct scm_data *scm_data = nvdimm_provider_data(nvdimm);
> > > +
> > > +     return scm_overwrite(scm_data);
> > > +}
> > > +
> > > +/**
> > > + * scm_secop_query_overwrite() - Get the current overwrite state
> > > + * @nvdimm: The nvdimm representation of the SCM device to start the overwrite on
> > > + * Return: 0 if successful or idle, -EBUSY if busy, -EFAULT if failed
> > > + */
> > > +static int scm_secop_query_overwrite(struct nvdimm *nvdimm)
> > > +{
> > > +     struct scm_data *scm_data = nvdimm_provider_data(nvdimm);
> > > +
> > > +     if (scm_data->overwrite_state == SCM_OVERWRITE_BUSY)
> > > +             return -EBUSY;
> > > +
> > > +     if (scm_data->overwrite_state == SCM_OVERWRITE_FAILED)
> > > +             return -EFAULT;
> > > +
> > > +     return 0;
> > > +}
> > > +
> > > +/**
> > > + * scm_secop_get_flags() - return the security flags for the SCM device
> > > + */
> > > +static unsigned long scm_secop_get_flags(struct nvdimm *nvdimm,
> > > +             enum nvdimm_passphrase_type ptype)
> > > +{
> > > +     struct scm_data *scm_data = nvdimm_provider_data(nvdimm);
> > > +
> > > +     if (scm_data->overwrite_state == SCM_OVERWRITE_BUSY)
> > > +             return BIT(NVDIMM_SECURITY_OVERWRITE);
> > > +
> > > +     return BIT(NVDIMM_SECURITY_DISABLED);
> > > +}
> > > +
> > > +static const struct nvdimm_security_ops sec_ops  = {
> > > +     .get_flags = scm_secop_get_flags,
> > > +     .overwrite = scm_secop_overwrite,
> > > +     .query_overwrite = scm_secop_query_overwrite,
> > > +};
> > > +
> > > +/**
> > > + * scm_register_lpc_mem() - Discover persistent memory on a device and register it with the NVDIMM subsystem
> > > + * @scm_data: The SCM device data
> > > + * Return: 0 on success
> > > + */
> > > +static int scm_register_lpc_mem(struct scm_data *scm_data)
> > > +{
> > > +     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(scm_data->ocxl_afu);
> > > +     if (rc < 0)
> > > +             return rc;
> > > +
> > > +     lpc_mem = ocxl_afu_lpc_mem(scm_data->ocxl_afu);
> > > +     if (lpc_mem == NULL)
> > > +             return -EINVAL;
> > > +
> > > +     config = ocxl_afu_config(scm_data->ocxl_afu);
> > > +     fn_config = ocxl_function_config(scm_data->ocxl_fn);
> > > +
> > > +     rc = scm_reserve_metadata(scm_data, lpc_mem);
> > > +     if (rc)
> > > +             return rc;
> > > +
> > > +     scm_data->bus_desc.attr_groups = scm_pmem_attribute_groups;
> > > +     scm_data->bus_desc.provider_name = "scm";
> > > +     scm_data->bus_desc.ndctl = scm_ndctl;
> > > +     scm_data->bus_desc.module = THIS_MODULE;
> > > +
> > > +     scm_data->nvdimm_bus = nvdimm_bus_register(&scm_data->dev,
> > > +                            &scm_data->bus_desc);
> > > +     if (!scm_data->nvdimm_bus)
> > > +             return -EINVAL;
> > > +
> > > +     scm_data->scm_res.start = (u64)lpc_mem->start + SCM_LABEL_AREA_SIZE;
> > > +     scm_data->scm_res.end = (u64)lpc_mem->start + config->lpc_mem_size - 1;
> > > +     scm_data->scm_res.name = "SCM 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(ND_CMD_SMART, &nvdimm_cmd_mask);
> > > +
> > > +     set_bit(NDD_ALIASING, &nvdimm_flags);
> > > +
> > > +     snprintf(serial, sizeof(serial), "%llx", fn_config->serial);
> > > +     nd_mapping_desc.nvdimm = __nvdimm_create(scm_data->nvdimm_bus, scm_data,
> > > +                              scm_dimm_attribute_groups,
> > > +                              nvdimm_flags, nvdimm_cmd_mask,
> > > +                              0, NULL, serial, &sec_ops);
> >
> >
> > nvdimm_create()?
> >
> > > +     if (!nd_mapping_desc.nvdimm)
> > > +             return -ENOMEM;
> > > +
> > > +     if (nvdimm_bus_check_dimm_count(scm_data->nvdimm_bus, 1))
> > > +             return -EINVAL;
> > > +
> > > +     nd_mapping_desc.start = scm_data->scm_res.start;
> > > +     nd_mapping_desc.size = resource_size(&scm_data->scm_res);
> > > +     nd_mapping_desc.position = 0;
> > > +
> > > +     scm_data->nd_set.cookie1 = fn_config->serial + 1; // allow for empty serial
> > > +     scm_data->nd_set.cookie2 = fn_config->serial + 1;
> > > +
> > > +     target_node = of_node_to_nid(scm_data->pdev->dev.of_node);
> > > +
> > > +     memset(&region_desc, 0, sizeof(region_desc));
> > > +     region_desc.res = &scm_data->scm_res;
> > > +     region_desc.attr_groups = scm_pmem_region_attribute_groups;
> > > +     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 = &scm_data->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.
> > > +      */
> > > +     scm_data->nd_region = nvdimm_pmem_region_create(scm_data->nvdimm_bus,
> > > +                           &region_desc);
> > > +     if (!scm_data->nd_region)
> > > +             return -EINVAL;
> > > +
> > > +     dev_info(&scm_data->dev,
> > > +              "Onlining %lluMB of persistent memory\n",
> > > +              nd_mapping_desc.size / SZ_1M);
> > > +
> > > +     return 0;
> > > +}
> > > +
> >
> > Would it be possible to split the driver such that we add features like
> > security ops in later patch? Can this patch be a baisc dirver that just get
> > the nvdimm initialized. Any attribute specific to ocxl can be exported
> > in follow up patches?
>
> Yes, please. This diffstat:
>
> 8 files changed, 3141 insertions(+), 1 deletion(-)
>
> ...is too big for a single patch, and one sentence of changelog for
> that diffstat is too small.
>
> You might look at the early history of driver/nvdimm/
> drivers/acpi/nfit* to get some ideas on how to break this up into
> smaller pieces that just do one theme per patch.

Also, given the timeframe / proximity to the v5.5 merge window opening
we're looking at the v5.6 merge window as the target.
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