Message-ID: <20150520205627.32249.80556.stgit@dwillia2-desk3.amr.corp.intel.com>
Date:	Wed, 20 May 2015 16:56:27 -0400
From:	Dan Williams <dan.j.williams@...el.com>
To:	axboe@...nel.dk
Cc:	mingo@...nel.org, linux-nvdimm@...ts.01.org, neilb@...e.de,
	gregkh@...uxfoundation.org,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Robert Moore <robert.moore@...el.com>,
	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
	jmoyer@...hat.com, hch@....de
Subject: [PATCH v3 03/21] libnd: control character device and libnd bus
 sysfs attributes

The control device for a libnd bus is registered as an "nd" class
device.  The expectation is that there will usually only be one "nd" bus
registered under /sys/class/nd.  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.  The initial command set has a 1:1 correlation with
the commands listed in the by the "NFIT DSM Example" document [1], but
this scheme is extensible to future command sets.

Note, nd_ioctl() and the backing ->ndctl() implementation are defined in
a subsequent patch.  This is simply the initial registrations and sysfs
attributes.

[1]: http://pmem.io/documents/NVDIMM_DSM_Interface_Example.pdf

Cc: Neil Brown <neilb@...e.de>
Cc: Greg KH <gregkh@...uxfoundation.org>
Cc: <linux-acpi@...r.kernel.org>
Cc: Robert Moore <robert.moore@...el.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
---
 drivers/acpi/nfit.c           |   29 ++++++++++++++
 drivers/acpi/nfit.h           |    5 ++
 drivers/block/nd/Makefile     |    1 
 drivers/block/nd/bus.c        |   83 +++++++++++++++++++++++++++++++++++++++
 drivers/block/nd/core.c       |   87 ++++++++++++++++++++++++++++++++++++++++-
 drivers/block/nd/nd-private.h |    6 +++
 include/linux/libnd.h         |    5 ++
 7 files changed, 214 insertions(+), 2 deletions(-)
 create mode 100644 drivers/block/nd/bus.c

diff --git a/drivers/acpi/nfit.c b/drivers/acpi/nfit.c
index 13132a16901c..d31a0fffafcc 100644
--- a/drivers/acpi/nfit.c
+++ b/drivers/acpi/nfit.c
@@ -316,6 +316,34 @@ static int nfit_mem_init(struct acpi_nfit_desc *acpi_desc)
 	return 0;
 }
 
+static ssize_t revision_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct nd_bus *nd_bus = to_nd_bus(dev);
+	struct nd_bus_descriptor *nd_desc = to_nd_desc(nd_bus);
+	struct acpi_nfit_desc *acpi_desc = to_acpi_desc(nd_desc);
+
+	return sprintf(buf, "%d\n", acpi_desc->nfit->header.revision);
+}
+static DEVICE_ATTR_RO(revision);
+
+static struct attribute *acpi_nfit_attributes[] = {
+	&dev_attr_revision.attr,
+	NULL,
+};
+
+static struct attribute_group acpi_nfit_attribute_group = {
+	.name = "nfit",
+	.attrs = acpi_nfit_attributes,
+};
+
+const struct attribute_group *acpi_nfit_attribute_groups[] = {
+	&nd_bus_attribute_group,
+	&acpi_nfit_attribute_group,
+	NULL,
+};
+EXPORT_SYMBOL_GPL(acpi_nfit_attribute_groups);
+
 static int acpi_nfit_init(struct acpi_nfit_desc *acpi_desc, acpi_size sz)
 {
 	struct device *dev = acpi_desc->dev;
@@ -372,6 +400,7 @@ static int acpi_nfit_add(struct acpi_device *adev)
 	nd_desc = &acpi_desc->nd_desc;
 	nd_desc->provider_name = "ACPI.NFIT";
 	nd_desc->ndctl = acpi_nfit_ctl;
+	nd_desc->attr_groups = acpi_nfit_attribute_groups;
 
 	acpi_desc->nd_bus = nd_bus_register(dev, nd_desc);
 	if (!acpi_desc->nd_bus)
diff --git a/drivers/acpi/nfit.h b/drivers/acpi/nfit.h
index ff72da9c9694..b6c85d773ca1 100644
--- a/drivers/acpi/nfit.h
+++ b/drivers/acpi/nfit.h
@@ -86,4 +86,9 @@ static inline struct acpi_nfit_memory_map *__to_nfit_memdev(struct nfit_mem *nfi
 		return nfit_mem->memdev_dcr;
 	return nfit_mem->memdev_pmem;
 }
+
+static inline struct acpi_nfit_desc *to_acpi_desc(struct nd_bus_descriptor *nd_desc)
+{
+	return container_of(nd_desc, struct acpi_nfit_desc, nd_desc);
+}
 #endif /* __NFIT_H__ */
diff --git a/drivers/block/nd/Makefile b/drivers/block/nd/Makefile
index a647ff6cf557..34d1b58b3258 100644
--- a/drivers/block/nd/Makefile
+++ b/drivers/block/nd/Makefile
@@ -1,3 +1,4 @@
 obj-$(CONFIG_LIBND) += libnd.o
 
 libnd-y := core.o
+libnd-y += bus.o
diff --git a/drivers/block/nd/bus.c b/drivers/block/nd/bus.c
new file mode 100644
index 000000000000..635f2e926426
--- /dev/null
+++ b/drivers/block/nd/bus.c
@@ -0,0 +1,83 @@
+/*
+ * 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"
+
+static int nd_bus_major;
+static struct class *nd_class;
+
+int nd_bus_create_ndctl(struct nd_bus *nd_bus)
+{
+	dev_t devt = MKDEV(nd_bus_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_bus_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_bus_major = rc;
+
+	nd_class = class_create(THIS_MODULE, "nd");
+	if (IS_ERR(nd_class))
+		goto err_class;
+
+	return 0;
+
+ err_class:
+	unregister_chrdev(nd_bus_major, "ndctl");
+
+	return rc;
+}
+
+void __exit nd_bus_exit(void)
+{
+	class_destroy(nd_class);
+	unregister_chrdev(nd_bus_major, "ndctl");
+}
diff --git a/drivers/block/nd/core.c b/drivers/block/nd/core.c
index 15b89ce1a9af..49b7ac8f7606 100644
--- a/drivers/block/nd/core.c
+++ b/drivers/block/nd/core.c
@@ -14,9 +14,12 @@
 #include <linux/module.h>
 #include <linux/device.h>
 #include <linux/libnd.h>
+#include <linux/mutex.h>
 #include <linux/slab.h>
 #include "nd-private.h"
 
+LIST_HEAD(nd_bus_list);
+DEFINE_MUTEX(nd_bus_list_mutex);
 static DEFINE_IDA(nd_ida);
 
 static void nd_bus_release(struct device *dev)
@@ -27,6 +30,54 @@ static void nd_bus_release(struct device *dev)
 	kfree(nd_bus);
 }
 
+struct nd_bus *to_nd_bus(struct device *dev)
+{
+	struct nd_bus *nd_bus = container_of(dev, struct nd_bus, dev);
+
+	WARN_ON(nd_bus->dev.release != nd_bus_release);
+	return nd_bus;
+}
+EXPORT_SYMBOL_GPL(to_nd_bus);
+
+struct nd_bus_descriptor *to_nd_desc(struct nd_bus *nd_bus)
+{
+	/* struct nd_bus definition is private to libnd */
+	return nd_bus->nd_desc;
+}
+EXPORT_SYMBOL_GPL(to_nd_desc);
+
+static const char *nd_bus_provider(struct nd_bus *nd_bus)
+{
+	struct nd_bus_descriptor *nd_desc = nd_bus->nd_desc;
+	struct device *parent = nd_bus->dev.parent;
+
+	if (nd_desc->provider_name)
+		return nd_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 struct attribute *nd_bus_attributes[] = {
+	&dev_attr_provider.attr,
+	NULL,
+};
+
+struct attribute_group nd_bus_attribute_group = {
+	.attrs = nd_bus_attributes,
+};
+EXPORT_SYMBOL_GPL(nd_bus_attribute_group);
+
 struct nd_bus *nd_bus_register(struct device *parent,
 		struct nd_bus_descriptor *nd_desc)
 {
@@ -35,6 +86,7 @@ struct nd_bus *nd_bus_register(struct device *parent,
 
 	if (!nd_bus)
 		return NULL;
+	INIT_LIST_HEAD(&nd_bus->list);
 	nd_bus->id = ida_simple_get(&nd_ida, 0, 0, GFP_KERNEL);
 	if (nd_bus->id < 0) {
 		kfree(nd_bus);
@@ -43,15 +95,26 @@ struct nd_bus *nd_bus_register(struct device *parent,
 	nd_bus->nd_desc = nd_desc;
 	nd_bus->dev.parent = parent;
 	nd_bus->dev.release = nd_bus_release;
+	nd_bus->dev.groups = nd_desc->attr_groups;
 	dev_set_name(&nd_bus->dev, "ndbus%d", nd_bus->id);
 	rc = device_register(&nd_bus->dev);
 	if (rc) {
 		dev_dbg(&nd_bus->dev, "device registration failed: %d\n", rc);
-		put_device(&nd_bus->dev);
-		return NULL;
+		goto err;
 	}
 
+	rc = nd_bus_create_ndctl(nd_bus);
+	if (rc)
+		goto err;
+
+	mutex_lock(&nd_bus_list_mutex);
+	list_add_tail(&nd_bus->list, &nd_bus_list);
+	mutex_unlock(&nd_bus_list_mutex);
+
 	return nd_bus;
+ err:
+	put_device(&nd_bus->dev);
+	return NULL;
 }
 EXPORT_SYMBOL_GPL(nd_bus_register);
 
@@ -59,9 +122,29 @@ void nd_bus_unregister(struct nd_bus *nd_bus)
 {
 	if (!nd_bus)
 		return;
+
+	mutex_lock(&nd_bus_list_mutex);
+	list_del_init(&nd_bus->list);
+	mutex_unlock(&nd_bus_list_mutex);
+
+	nd_bus_destroy_ndctl(nd_bus);
+
 	device_unregister(&nd_bus->dev);
 }
 EXPORT_SYMBOL_GPL(nd_bus_unregister);
 
+static __init int libnd_init(void)
+{
+	return nd_bus_init();
+}
+
+static __exit void libnd_exit(void)
+{
+	WARN_ON(!list_empty(&nd_bus_list));
+	nd_bus_exit();
+}
+
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Intel Corporation");
+module_init(libnd_init);
+module_exit(libnd_exit);
diff --git a/drivers/block/nd/nd-private.h b/drivers/block/nd/nd-private.h
index a107a19ffa9c..884601f65a15 100644
--- a/drivers/block/nd/nd-private.h
+++ b/drivers/block/nd/nd-private.h
@@ -17,7 +17,13 @@
 
 struct nd_bus {
 	struct nd_bus_descriptor *nd_desc;
+	struct list_head list;
 	struct device dev;
 	int id;
 };
+
+int __init nd_bus_init(void);
+void __exit nd_bus_exit(void);
+int nd_bus_create_ndctl(struct nd_bus *nd_bus);
+void nd_bus_destroy_ndctl(struct nd_bus *nd_bus);
 #endif /* __ND_PRIVATE_H__ */
diff --git a/include/linux/libnd.h b/include/linux/libnd.h
index 8e4441002868..04a97653d56c 100644
--- a/include/linux/libnd.h
+++ b/include/linux/libnd.h
@@ -14,6 +14,8 @@
  */
 #ifndef __LIBND_H__
 #define __LIBND_H__
+extern struct attribute_group nd_bus_attribute_group;
+
 struct nd_dimm;
 struct nd_bus_descriptor;
 typedef int (*ndctl_fn)(struct nd_bus_descriptor *nd_desc,
@@ -21,6 +23,7 @@ typedef int (*ndctl_fn)(struct nd_bus_descriptor *nd_desc,
 		unsigned int buf_len);
 
 struct nd_bus_descriptor {
+	const struct attribute_group **attr_groups;
 	unsigned long dsm_mask;
 	char *provider_name;
 	ndctl_fn ndctl;
@@ -31,4 +34,6 @@ struct device;
 struct nd_bus *nd_bus_register(struct device *parent,
 		struct nd_bus_descriptor *nfit_desc);
 void nd_bus_unregister(struct nd_bus *nd_bus);
+struct nd_bus *to_nd_bus(struct device *dev);
+struct nd_bus_descriptor *to_nd_desc(struct nd_bus *nd_bus);
 #endif /* __LIBND_H__ */

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