Re: [PATCH 06/21] nd: ndctl class device, and nd bus attributes

2015-04-18 Thread Dan Williams 
On Sat, Apr 18, 2015 at 1:07 AM, Greg KH  wrote:
> On Fri, Apr 17, 2015 at 09:35:46PM -0400, Dan Williams wrote:
>> This is the position (device topology) independent method to find all
>> the NFIT-defined buses in the system.  The expectation is that there
>> will only ever be one "nd" bus discovered via /sys/class/nd/ndctl0.
>> However, we allow for the possibility of multiple buses and they will
>> listed in discovery order as ndctl0...ndctlN.  This character device
>> hosts the ioctl for passing control messages (as defined by the NFIT
>> spec).  The "format" and "revision" attributes of this device identify
>> the format of the messages.  In the event an NFIT is registered with an
>> unknown/unsupported control message format then the "format" attribute
>> will not be visible.
>>
>> Cc: Greg KH 
>> Cc: Neil Brown 
>> Signed-off-by: Dan Williams 
>> ---
>>  drivers/block/nd/Makefile |1
>>  drivers/block/nd/bus.c|   84 
>> +
>>  drivers/block/nd/core.c   |   71 ++-
>>  drivers/block/nd/nd-private.h |5 ++
>>  4 files changed, 160 insertions(+), 1 deletion(-)
>>  create mode 100644 drivers/block/nd/bus.c
>>
>> diff --git a/drivers/block/nd/Makefile b/drivers/block/nd/Makefile
>> index c6bec0c185c5..7772fb599809 100644
>> --- a/drivers/block/nd/Makefile
>> +++ b/drivers/block/nd/Makefile
>> @@ -20,3 +20,4 @@ obj-$(CONFIG_NFIT_ACPI) += nd_acpi.o
>>  nd_acpi-y := acpi.o
>>
>>  nd-y := core.o
>> +nd-y += bus.o
>> diff --git a/drivers/block/nd/bus.c b/drivers/block/nd/bus.c
>> new file mode 100644
>> index ..c27db50511f2
>> --- /dev/null
>> +++ b/drivers/block/nd/bus.c
>> @@ -0,0 +1,84 @@
>> +/*
>> + * Copyright(c) 2013-2015 Intel Corporation. All rights reserved.
>> + *
>> + * 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.
>> + *
>> + * This program is distributed in the hope that it will be useful, but
>> + * WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>> + * General Public License for more details.
>> + */
>> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>> +#include 
>> +#include 
>> +#include 
>> +#include 
>> +#include 
>> +#include "nd-private.h"
>> +#include "nfit.h"
>> +
>> +static int nd_major;
>> +static struct class *nd_class;
>> +
>> +int nd_bus_create_ndctl(struct nd_bus *nd_bus)
>> +{
>> + dev_t devt = MKDEV(nd_major, nd_bus->id);
>> + struct device *dev;
>> +
>> + dev = device_create(nd_class, _bus->dev, devt, nd_bus, "ndctl%d",
>> + nd_bus->id);
>> +
>> + if (IS_ERR(dev)) {
>> + dev_dbg(_bus->dev, "failed to register ndctl%d: %ld\n",
>> + nd_bus->id, PTR_ERR(dev));
>> + return PTR_ERR(dev);
>> + }
>> + return 0;
>> +}
>> +
>> +void nd_bus_destroy_ndctl(struct nd_bus *nd_bus)
>> +{
>> + device_destroy(nd_class, MKDEV(nd_major, nd_bus->id));
>> +}
>> +
>> +static long nd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>> +{
>> + return -ENXIO;
>> +}
>
> There is no ioctl call here, so why even have this character device?

Our management library finds nd buses by /sys/class/nd.  The
nd_ioctl() gets filled out in "[PATCH 08/21] nd: ndctl.h, the nd ioctl
abi".
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Re: [PATCH 06/21] nd: ndctl class device, and nd bus attributes

2015-04-18 Thread Greg KH 
On Fri, Apr 17, 2015 at 09:35:46PM -0400, Dan Williams wrote:
> This is the position (device topology) independent method to find all
> the NFIT-defined buses in the system.  The expectation is that there
> will only ever be one "nd" bus discovered via /sys/class/nd/ndctl0.
> However, we allow for the possibility of multiple buses and they will
> listed in discovery order as ndctl0...ndctlN.  This character device
> hosts the ioctl for passing control messages (as defined by the NFIT
> spec).  The "format" and "revision" attributes of this device identify
> the format of the messages.  In the event an NFIT is registered with an
> unknown/unsupported control message format then the "format" attribute
> will not be visible.
> 
> Cc: Greg KH 
> Cc: Neil Brown 
> Signed-off-by: Dan Williams 
> ---
>  drivers/block/nd/Makefile |1 
>  drivers/block/nd/bus.c|   84 
> +
>  drivers/block/nd/core.c   |   71 ++-
>  drivers/block/nd/nd-private.h |5 ++
>  4 files changed, 160 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/block/nd/bus.c
> 
> diff --git a/drivers/block/nd/Makefile b/drivers/block/nd/Makefile
> index c6bec0c185c5..7772fb599809 100644
> --- a/drivers/block/nd/Makefile
> +++ b/drivers/block/nd/Makefile
> @@ -20,3 +20,4 @@ obj-$(CONFIG_NFIT_ACPI) += nd_acpi.o
>  nd_acpi-y := acpi.o
>  
>  nd-y := core.o
> +nd-y += bus.o
> diff --git a/drivers/block/nd/bus.c b/drivers/block/nd/bus.c
> new file mode 100644
> index ..c27db50511f2
> --- /dev/null
> +++ b/drivers/block/nd/bus.c
> @@ -0,0 +1,84 @@
> +/*
> + * Copyright(c) 2013-2015 Intel Corporation. All rights reserved.
> + *
> + * 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.
> + *
> + * This program is distributed in the hope that it will be useful, but
> + * WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * General Public License for more details.
> + */
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include "nd-private.h"
> +#include "nfit.h"
> +
> +static int nd_major;
> +static struct class *nd_class;
> +
> +int nd_bus_create_ndctl(struct nd_bus *nd_bus)
> +{
> + dev_t devt = MKDEV(nd_major, nd_bus->id);
> + struct device *dev;
> +
> + dev = device_create(nd_class, _bus->dev, devt, nd_bus, "ndctl%d",
> + nd_bus->id);
> +
> + if (IS_ERR(dev)) {
> + dev_dbg(_bus->dev, "failed to register ndctl%d: %ld\n",
> + nd_bus->id, PTR_ERR(dev));
> + return PTR_ERR(dev);
> + }
> + return 0;
> +}
> +
> +void nd_bus_destroy_ndctl(struct nd_bus *nd_bus)
> +{
> + device_destroy(nd_class, MKDEV(nd_major, nd_bus->id));
> +}
> +
> +static long nd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> +{
> + return -ENXIO;
> +}

There is no ioctl call here, so why even have this character device?

thanks,

greg k-h
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Re: [PATCH 06/21] nd: ndctl class device, and nd bus attributes

2015-04-18 Thread Dan Williams 
On Sat, Apr 18, 2015 at 1:07 AM, Greg KH gre...@linuxfoundation.org wrote:
 On Fri, Apr 17, 2015 at 09:35:46PM -0400, Dan Williams wrote:
 This is the position (device topology) independent method to find all
 the NFIT-defined buses in the system.  The expectation is that there
 will only ever be one nd bus discovered via /sys/class/nd/ndctl0.
 However, we allow for the possibility of multiple buses and they will
 listed in discovery order as ndctl0...ndctlN.  This character device
 hosts the ioctl for passing control messages (as defined by the NFIT
 spec).  The format and revision attributes of this device identify
 the format of the messages.  In the event an NFIT is registered with an
 unknown/unsupported control message format then the format attribute
 will not be visible.

 Cc: Greg KH gre...@linuxfoundation.org
 Cc: Neil Brown ne...@suse.de
 Signed-off-by: Dan Williams dan.j.willi...@intel.com
 ---
  drivers/block/nd/Makefile |1
  drivers/block/nd/bus.c|   84 
 +
  drivers/block/nd/core.c   |   71 ++-
  drivers/block/nd/nd-private.h |5 ++
  4 files changed, 160 insertions(+), 1 deletion(-)
  create mode 100644 drivers/block/nd/bus.c

 diff --git a/drivers/block/nd/Makefile b/drivers/block/nd/Makefile
 index c6bec0c185c5..7772fb599809 100644
 --- a/drivers/block/nd/Makefile
 +++ b/drivers/block/nd/Makefile
 @@ -20,3 +20,4 @@ obj-$(CONFIG_NFIT_ACPI) += nd_acpi.o
  nd_acpi-y := acpi.o

  nd-y := core.o
 +nd-y += bus.o
 diff --git a/drivers/block/nd/bus.c b/drivers/block/nd/bus.c
 new file mode 100644
 index ..c27db50511f2
 --- /dev/null
 +++ b/drivers/block/nd/bus.c
 @@ -0,0 +1,84 @@
 +/*
 + * Copyright(c) 2013-2015 Intel Corporation. All rights reserved.
 + *
 + * 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.
 + *
 + * This program is distributed in the hope that it will be useful, but
 + * WITHOUT ANY WARRANTY; without even the implied warranty of
 + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 + * General Public License for more details.
 + */
 +#define pr_fmt(fmt) KBUILD_MODNAME :  fmt
 +#include linux/uaccess.h
 +#include linux/fcntl.h
 +#include linux/slab.h
 +#include linux/fs.h
 +#include linux/io.h
 +#include nd-private.h
 +#include nfit.h
 +
 +static int nd_major;
 +static struct class *nd_class;
 +
 +int nd_bus_create_ndctl(struct nd_bus *nd_bus)
 +{
 + dev_t devt = MKDEV(nd_major, nd_bus-id);
 + struct device *dev;
 +
 + dev = device_create(nd_class, nd_bus-dev, devt, nd_bus, ndctl%d,
 + nd_bus-id);
 +
 + if (IS_ERR(dev)) {
 + dev_dbg(nd_bus-dev, failed to register ndctl%d: %ld\n,
 + nd_bus-id, PTR_ERR(dev));
 + return PTR_ERR(dev);
 + }
 + return 0;
 +}
 +
 +void nd_bus_destroy_ndctl(struct nd_bus *nd_bus)
 +{
 + device_destroy(nd_class, MKDEV(nd_major, nd_bus-id));
 +}
 +
 +static long nd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 +{
 + return -ENXIO;
 +}

 There is no ioctl call here, so why even have this character device?

Our management library finds nd buses by /sys/class/nd.  The
nd_ioctl() gets filled out in [PATCH 08/21] nd: ndctl.h, the nd ioctl
abi.
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Re: [PATCH 06/21] nd: ndctl class device, and nd bus attributes

2015-04-18 Thread Greg KH 
On Fri, Apr 17, 2015 at 09:35:46PM -0400, Dan Williams wrote:
 This is the position (device topology) independent method to find all
 the NFIT-defined buses in the system.  The expectation is that there
 will only ever be one nd bus discovered via /sys/class/nd/ndctl0.
 However, we allow for the possibility of multiple buses and they will
 listed in discovery order as ndctl0...ndctlN.  This character device
 hosts the ioctl for passing control messages (as defined by the NFIT
 spec).  The format and revision attributes of this device identify
 the format of the messages.  In the event an NFIT is registered with an
 unknown/unsupported control message format then the format attribute
 will not be visible.
 
 Cc: Greg KH gre...@linuxfoundation.org
 Cc: Neil Brown ne...@suse.de
 Signed-off-by: Dan Williams dan.j.willi...@intel.com
 ---
  drivers/block/nd/Makefile |1 
  drivers/block/nd/bus.c|   84 
 +
  drivers/block/nd/core.c   |   71 ++-
  drivers/block/nd/nd-private.h |5 ++
  4 files changed, 160 insertions(+), 1 deletion(-)
  create mode 100644 drivers/block/nd/bus.c
 
 diff --git a/drivers/block/nd/Makefile b/drivers/block/nd/Makefile
 index c6bec0c185c5..7772fb599809 100644
 --- a/drivers/block/nd/Makefile
 +++ b/drivers/block/nd/Makefile
 @@ -20,3 +20,4 @@ obj-$(CONFIG_NFIT_ACPI) += nd_acpi.o
  nd_acpi-y := acpi.o
  
  nd-y := core.o
 +nd-y += bus.o
 diff --git a/drivers/block/nd/bus.c b/drivers/block/nd/bus.c
 new file mode 100644
 index ..c27db50511f2
 --- /dev/null
 +++ b/drivers/block/nd/bus.c
 @@ -0,0 +1,84 @@
 +/*
 + * Copyright(c) 2013-2015 Intel Corporation. All rights reserved.
 + *
 + * 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.
 + *
 + * This program is distributed in the hope that it will be useful, but
 + * WITHOUT ANY WARRANTY; without even the implied warranty of
 + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 + * General Public License for more details.
 + */
 +#define pr_fmt(fmt) KBUILD_MODNAME :  fmt
 +#include linux/uaccess.h
 +#include linux/fcntl.h
 +#include linux/slab.h
 +#include linux/fs.h
 +#include linux/io.h
 +#include nd-private.h
 +#include nfit.h
 +
 +static int nd_major;
 +static struct class *nd_class;
 +
 +int nd_bus_create_ndctl(struct nd_bus *nd_bus)
 +{
 + dev_t devt = MKDEV(nd_major, nd_bus-id);
 + struct device *dev;
 +
 + dev = device_create(nd_class, nd_bus-dev, devt, nd_bus, ndctl%d,
 + nd_bus-id);
 +
 + if (IS_ERR(dev)) {
 + dev_dbg(nd_bus-dev, failed to register ndctl%d: %ld\n,
 + nd_bus-id, PTR_ERR(dev));
 + return PTR_ERR(dev);
 + }
 + return 0;
 +}
 +
 +void nd_bus_destroy_ndctl(struct nd_bus *nd_bus)
 +{
 + device_destroy(nd_class, MKDEV(nd_major, nd_bus-id));
 +}
 +
 +static long nd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 +{
 + return -ENXIO;
 +}

There is no ioctl call here, so why even have this character device?

thanks,

greg k-h
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[PATCH 06/21] nd: ndctl class device, and nd bus attributes

2015-04-17 Thread Dan Williams 
This is the position (device topology) independent method to find all
the NFIT-defined buses in the system.  The expectation is that there
will only ever be one "nd" bus discovered via /sys/class/nd/ndctl0.
However, we allow for the possibility of multiple buses and they will
listed in discovery order as ndctl0...ndctlN.  This character device
hosts the ioctl for passing control messages (as defined by the NFIT
spec).  The "format" and "revision" attributes of this device identify
the format of the messages.  In the event an NFIT is registered with an
unknown/unsupported control message format then the "format" attribute
will not be visible.

Cc: Greg KH 
Cc: Neil Brown 
Signed-off-by: Dan Williams 
---
 drivers/block/nd/Makefile |1 
 drivers/block/nd/bus.c|   84 +
 drivers/block/nd/core.c   |   71 ++-
 drivers/block/nd/nd-private.h |5 ++
 4 files changed, 160 insertions(+), 1 deletion(-)
 create mode 100644 drivers/block/nd/bus.c

diff --git a/drivers/block/nd/Makefile b/drivers/block/nd/Makefile
index c6bec0c185c5..7772fb599809 100644
--- a/drivers/block/nd/Makefile
+++ b/drivers/block/nd/Makefile
@@ -20,3 +20,4 @@ obj-$(CONFIG_NFIT_ACPI) += nd_acpi.o
 nd_acpi-y := acpi.o
 
 nd-y := core.o
+nd-y += bus.o
diff --git a/drivers/block/nd/bus.c b/drivers/block/nd/bus.c
new file mode 100644
index ..c27db50511f2
--- /dev/null
+++ b/drivers/block/nd/bus.c
@@ -0,0 +1,84 @@
+/*
+ * Copyright(c) 2013-2015 Intel Corporation. All rights reserved.
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include 
+#include 
+#include 
+#include 
+#include 
+#include "nd-private.h"
+#include "nfit.h"
+
+static int nd_major;
+static struct class *nd_class;
+
+int nd_bus_create_ndctl(struct nd_bus *nd_bus)
+{
+   dev_t devt = MKDEV(nd_major, nd_bus->id);
+   struct device *dev;
+
+   dev = device_create(nd_class, _bus->dev, devt, nd_bus, "ndctl%d",
+   nd_bus->id);
+
+   if (IS_ERR(dev)) {
+   dev_dbg(_bus->dev, "failed to register ndctl%d: %ld\n",
+   nd_bus->id, PTR_ERR(dev));
+   return PTR_ERR(dev);
+   }
+   return 0;
+}
+
+void nd_bus_destroy_ndctl(struct nd_bus *nd_bus)
+{
+   device_destroy(nd_class, MKDEV(nd_major, nd_bus->id));
+}
+
+static long nd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+   return -ENXIO;
+}
+
+static const struct file_operations nd_bus_fops = {
+   .owner = THIS_MODULE,
+   .open = nonseekable_open,
+   .unlocked_ioctl = nd_ioctl,
+   .compat_ioctl = nd_ioctl,
+   .llseek = noop_llseek,
+};
+
+int __init nd_bus_init(void)
+{
+   int rc;
+
+   rc = register_chrdev(0, "ndctl", _bus_fops);
+   if (rc < 0)
+   return rc;
+   nd_major = rc;
+
+   nd_class = class_create(THIS_MODULE, "nd");
+   if (IS_ERR(nd_class))
+   goto err_class;
+
+   return 0;
+
+ err_class:
+   unregister_chrdev(nd_major, "ndctl");
+
+   return rc;
+}
+
+void __exit nd_bus_exit(void)
+{
+   class_destroy(nd_class);
+   unregister_chrdev(nd_major, "ndctl");
+}
diff --git a/drivers/block/nd/core.c b/drivers/block/nd/core.c
index d126799e7ff7..d6a666b9228b 100644
--- a/drivers/block/nd/core.c
+++ b/drivers/block/nd/core.c
@@ -14,12 +14,15 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 #include 
 #include 
 #include "nd-private.h"
 #include "nfit.h"
 
+LIST_HEAD(nd_bus_list);
+DEFINE_MUTEX(nd_bus_list_mutex);
 static DEFINE_IDA(nd_ida);
 
 static bool warn_checksum;
@@ -68,6 +71,53 @@ struct nd_bus *to_nd_bus(struct device *dev)
return nd_bus;
 }
 
+static const char *nd_bus_provider(struct nd_bus *nd_bus)
+{
+   struct nfit_bus_descriptor *nfit_desc = nd_bus->nfit_desc;
+   struct device *parent = nd_bus->dev.parent;
+
+   if (nfit_desc->provider_name)
+   return nfit_desc->provider_name;
+   else if (parent)
+   return dev_name(parent);
+   else
+   return "unknown";
+}
+
+static ssize_t provider_show(struct device *dev,
+   struct device_attribute *attr, char *buf)
+{
+   struct nd_bus *nd_bus = to_nd_bus(dev);
+
+   return sprintf(buf, "%s\n", nd_bus_provider(nd_bus));
+}
+static DEVICE_ATTR_RO(provider);
+
+static ssize_t revision_show(struct device *dev,
+   struct device_attribute *attr, char *buf)
+{
+   struct nd_bus *nd_bus = to_nd_bus(dev);
+

[PATCH 06/21] nd: ndctl class device, and nd bus attributes

2015-04-17 Thread Dan Williams 
This is the position (device topology) independent method to find all
the NFIT-defined buses in the system.  The expectation is that there
will only ever be one nd bus discovered via /sys/class/nd/ndctl0.
However, we allow for the possibility of multiple buses and they will
listed in discovery order as ndctl0...ndctlN.  This character device
hosts the ioctl for passing control messages (as defined by the NFIT
spec).  The format and revision attributes of this device identify
the format of the messages.  In the event an NFIT is registered with an
unknown/unsupported control message format then the format attribute
will not be visible.

Cc: Greg KH gre...@linuxfoundation.org
Cc: Neil Brown ne...@suse.de
Signed-off-by: Dan Williams dan.j.willi...@intel.com
---
 drivers/block/nd/Makefile |1 
 drivers/block/nd/bus.c|   84 +
 drivers/block/nd/core.c   |   71 ++-
 drivers/block/nd/nd-private.h |5 ++
 4 files changed, 160 insertions(+), 1 deletion(-)
 create mode 100644 drivers/block/nd/bus.c

diff --git a/drivers/block/nd/Makefile b/drivers/block/nd/Makefile
index c6bec0c185c5..7772fb599809 100644
--- a/drivers/block/nd/Makefile
+++ b/drivers/block/nd/Makefile
@@ -20,3 +20,4 @@ obj-$(CONFIG_NFIT_ACPI) += nd_acpi.o
 nd_acpi-y := acpi.o
 
 nd-y := core.o
+nd-y += bus.o
diff --git a/drivers/block/nd/bus.c b/drivers/block/nd/bus.c
new file mode 100644
index ..c27db50511f2
--- /dev/null
+++ b/drivers/block/nd/bus.c
@@ -0,0 +1,84 @@
+/*
+ * Copyright(c) 2013-2015 Intel Corporation. All rights reserved.
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME :  fmt
+#include linux/uaccess.h
+#include linux/fcntl.h
+#include linux/slab.h
+#include linux/fs.h
+#include linux/io.h
+#include nd-private.h
+#include nfit.h
+
+static int nd_major;
+static struct class *nd_class;
+
+int nd_bus_create_ndctl(struct nd_bus *nd_bus)
+{
+   dev_t devt = MKDEV(nd_major, nd_bus-id);
+   struct device *dev;
+
+   dev = device_create(nd_class, nd_bus-dev, devt, nd_bus, ndctl%d,
+   nd_bus-id);
+
+   if (IS_ERR(dev)) {
+   dev_dbg(nd_bus-dev, failed to register ndctl%d: %ld\n,
+   nd_bus-id, PTR_ERR(dev));
+   return PTR_ERR(dev);
+   }
+   return 0;
+}
+
+void nd_bus_destroy_ndctl(struct nd_bus *nd_bus)
+{
+   device_destroy(nd_class, MKDEV(nd_major, nd_bus-id));
+}
+
+static long nd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+   return -ENXIO;
+}
+
+static const struct file_operations nd_bus_fops = {
+   .owner = THIS_MODULE,
+   .open = nonseekable_open,
+   .unlocked_ioctl = nd_ioctl,
+   .compat_ioctl = nd_ioctl,
+   .llseek = noop_llseek,
+};
+
+int __init nd_bus_init(void)
+{
+   int rc;
+
+   rc = register_chrdev(0, ndctl, nd_bus_fops);
+   if (rc  0)
+   return rc;
+   nd_major = rc;
+
+   nd_class = class_create(THIS_MODULE, nd);
+   if (IS_ERR(nd_class))
+   goto err_class;
+
+   return 0;
+
+ err_class:
+   unregister_chrdev(nd_major, ndctl);
+
+   return rc;
+}
+
+void __exit nd_bus_exit(void)
+{
+   class_destroy(nd_class);
+   unregister_chrdev(nd_major, ndctl);
+}
diff --git a/drivers/block/nd/core.c b/drivers/block/nd/core.c
index d126799e7ff7..d6a666b9228b 100644
--- a/drivers/block/nd/core.c
+++ b/drivers/block/nd/core.c
@@ -14,12 +14,15 @@
 #include linux/export.h
 #include linux/module.h
 #include linux/device.h
+#include linux/mutex.h
 #include linux/slab.h
 #include linux/uuid.h
 #include linux/io.h
 #include nd-private.h
 #include nfit.h
 
+LIST_HEAD(nd_bus_list);
+DEFINE_MUTEX(nd_bus_list_mutex);
 static DEFINE_IDA(nd_ida);
 
 static bool warn_checksum;
@@ -68,6 +71,53 @@ struct nd_bus *to_nd_bus(struct device *dev)
return nd_bus;
 }
 
+static const char *nd_bus_provider(struct nd_bus *nd_bus)
+{
+   struct nfit_bus_descriptor *nfit_desc = nd_bus-nfit_desc;
+   struct device *parent = nd_bus-dev.parent;
+
+   if (nfit_desc-provider_name)
+   return nfit_desc-provider_name;
+   else if (parent)
+   return dev_name(parent);
+   else
+   return unknown;
+}
+
+static ssize_t provider_show(struct device *dev,
+   struct device_attribute *attr, char *buf)
+{
+   struct nd_bus *nd_bus = to_nd_bus(dev);
+
+   return sprintf(buf, %s\n, nd_bus_provider(nd_bus));
+}
+static