lightnvm: expose device geometry through sysfs

For a host to access an Open-Channel SSD, it has to know its geometry,
so that it writes and reads at the appropriate device bounds.

Currently, the geometry information is kept within the kernel, and not
exported to user-space for consumption. This patch exposes the
configuration through sysfs and enables user-space libraries, such as
liblightnvm, to use the sysfs implementation to get the geometry of an
Open-Channel SSD.

The sysfs entries are stored within the device hierarchy, and can be
found using the "lightnvm" device type.

An example configuration looks like this:

/sys/class/nvme/
└── nvme0n1
   ├── capabilities: 3
   ├── device_mode: 1
   ├── erase_max: 1000000
   ├── erase_typ: 1000000
   ├── flash_media_type: 0
   ├── media_capabilities: 0x00000001
   ├── media_type: 0
   ├── multiplane: 0x00010101
   ├── num_blocks: 1022
   ├── num_channels: 1
   ├── num_luns: 4
   ├── num_pages: 64
   ├── num_planes: 1
   ├── page_size: 4096
   ├── prog_max: 100000
   ├── prog_typ: 100000
   ├── read_max: 10000
   ├── read_typ: 10000
   ├── sector_oob_size: 0
   ├── sector_size: 4096
   ├── media_manager: gennvm
   ├── ppa_format: 0x380830082808001010102008
   ├── vendor_opcode: 0
   ├── max_phys_secs: 64
   └── version: 1

Signed-off-by: Simon A. F. Lund <slund@cnexlabs.com>
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

4 files changed, 245 insertions, 7 deletions

diff --git a/drivers/lightnvm/Makefile b/drivers/lightnvm/Makefile
index a7a0a22cf1a5..1f6b6521016a 100644
--- a/drivers/lightnvm/Makefile
+++ b/drivers/lightnvm/Makefile
@@ -2,6 +2,6 @@
 # Makefile for Open-Channel SSDs.
 #
 
-obj-$(CONFIG_NVM)		:= core.o sysblk.o
+obj-$(CONFIG_NVM)		:= core.o sysblk.o sysfs.o
 obj-$(CONFIG_NVM_GENNVM) 	+= gennvm.o
 obj-$(CONFIG_NVM_RRPC)		+= rrpc.o
diff --git a/drivers/lightnvm/core.c b/drivers/lightnvm/core.c
index a99b59d1eb36..a2393e1ef82e 100644
--- a/drivers/lightnvm/core.c
+++ b/drivers/lightnvm/core.c
@@ -27,6 +27,8 @@
 #include <linux/lightnvm.h>
 #include <linux/sched/sysctl.h>
 
+#include "lightnvm.h"
+
 static LIST_HEAD(nvm_tgt_types);
 static DECLARE_RWSEM(nvm_tgtt_lock);
 static LIST_HEAD(nvm_mgrs);
@@ -598,15 +600,19 @@ static void nvm_free_mgr(struct nvm_dev *dev)
 	dev->mt = NULL;
 }
 
-static void nvm_free(struct nvm_dev *dev)
+void nvm_free(struct nvm_dev *dev)
 {
 	if (!dev)
 		return;
 
 	nvm_free_mgr(dev);
 
+	if (dev->dma_pool)
+		dev->ops->destroy_dma_pool(dev->dma_pool);
+
 	kfree(dev->lptbl);
 	kfree(dev->lun_map);
+	kfree(dev);
 }
 
 static int nvm_init(struct nvm_dev *dev)
@@ -653,11 +659,7 @@ err:
 
 static void nvm_exit(struct nvm_dev *dev)
 {
-	if (dev->dma_pool)
-		dev->ops->destroy_dma_pool(dev->dma_pool);
-	nvm_free(dev);
-
-	pr_info("nvm: successfully unloaded\n");
+	nvm_sysfs_unregister_dev(dev);
 }
 
 struct nvm_dev *nvm_alloc_dev(int node)
@@ -689,6 +691,10 @@ int nvm_register(struct nvm_dev *dev)
 		}
 	}
 
+	ret = nvm_sysfs_register_dev(dev);
+	if (ret)
+		goto err_ppalist;
+
 	if (dev->identity.cap & NVM_ID_DCAP_BBLKMGMT) {
 		ret = nvm_get_sysblock(dev, &dev->sb);
 		if (!ret)
@@ -705,6 +711,8 @@ int nvm_register(struct nvm_dev *dev)
 	up_write(&nvm_lock);
 
 	return 0;
+err_ppalist:
+	dev->ops->destroy_dma_pool(dev->dma_pool);
 err_init:
 	kfree(dev->lun_map);
 	return ret;
diff --git a/drivers/lightnvm/lightnvm.h b/drivers/lightnvm/lightnvm.h
new file mode 100644
index 000000000000..93f1aacc9f02
--- /dev/null
+++ b/drivers/lightnvm/lightnvm.h
@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2016 CNEX Labs. All rights reserved.
+ * Initial release: Matias Bjorling <matias@cnexlabs.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
+ * USA.
+ *
+ */
+
+#ifndef LIGHTNVM_H
+#define LIGHTNVM_H
+
+#include <linux/lightnvm.h>
+
+/* core -> sysfs.c */
+int nvm_sysfs_register_dev(struct nvm_dev *);
+void nvm_sysfs_unregister_dev(struct nvm_dev *);
+int nvm_sysfs_register(void);
+void nvm_sysfs_unregister(void);
+
+/* sysfs > core */
+void nvm_free(struct nvm_dev *);
+
+#endif
diff --git a/drivers/lightnvm/sysfs.c b/drivers/lightnvm/sysfs.c
new file mode 100644
index 000000000000..72ad089c0269
--- /dev/null
+++ b/drivers/lightnvm/sysfs.c
@@ -0,0 +1,195 @@
+#include <linux/kernel.h>
+#include <linux/lightnvm.h>
+#include <linux/miscdevice.h>
+#include <linux/kobject.h>
+#include <linux/blk-mq.h>
+
+#include "lightnvm.h"
+
+static ssize_t nvm_dev_attr_show(struct device *dev,
+				 struct device_attribute *dattr, char *page)
+{
+	struct nvm_dev *ndev = container_of(dev, struct nvm_dev, dev);
+	struct nvm_id *id = &ndev->identity;
+	struct nvm_id_group *grp = &id->groups[0];
+	struct attribute *attr = &dattr->attr;
+
+	if (strcmp(attr->name, "version") == 0) {
+		return scnprintf(page, PAGE_SIZE, "%u\n", id->ver_id);
+	} else if (strcmp(attr->name, "vendor_opcode") == 0) {
+		return scnprintf(page, PAGE_SIZE, "%u\n", id->vmnt);
+	} else if (strcmp(attr->name, "capabilities") == 0) {
+		return scnprintf(page, PAGE_SIZE, "%u\n", id->cap);
+	} else if (strcmp(attr->name, "device_mode") == 0) {
+		return scnprintf(page, PAGE_SIZE, "%u\n", id->dom);
+	} else if (strcmp(attr->name, "media_manager") == 0) {
+		if (!ndev->mt)
+			return scnprintf(page, PAGE_SIZE, "%s\n", "none");
+		return scnprintf(page, PAGE_SIZE, "%s\n", ndev->mt->name);
+	} else if (strcmp(attr->name, "ppa_format") == 0) {
+		return scnprintf(page, PAGE_SIZE,
+			"0x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x\n",
+			id->ppaf.ch_offset, id->ppaf.ch_len,
+			id->ppaf.lun_offset, id->ppaf.lun_len,
+			id->ppaf.pln_offset, id->ppaf.pln_len,
+			id->ppaf.blk_offset, id->ppaf.blk_len,
+			id->ppaf.pg_offset, id->ppaf.pg_len,
+			id->ppaf.sect_offset, id->ppaf.sect_len);
+	} else if (strcmp(attr->name, "media_type") == 0) {	/* u8 */
+		return scnprintf(page, PAGE_SIZE, "%u\n", grp->mtype);
+	} else if (strcmp(attr->name, "flash_media_type") == 0) {
+		return scnprintf(page, PAGE_SIZE, "%u\n", grp->fmtype);
+	} else if (strcmp(attr->name, "num_channels") == 0) {
+		return scnprintf(page, PAGE_SIZE, "%u\n", grp->num_ch);
+	} else if (strcmp(attr->name, "num_luns") == 0) {
+		return scnprintf(page, PAGE_SIZE, "%u\n", grp->num_lun);
+	} else if (strcmp(attr->name, "num_planes") == 0) {
+		return scnprintf(page, PAGE_SIZE, "%u\n", grp->num_pln);
+	} else if (strcmp(attr->name, "num_blocks") == 0) {	/* u16 */
+		return scnprintf(page, PAGE_SIZE, "%u\n", grp->num_blk);
+	} else if (strcmp(attr->name, "num_pages") == 0) {
+		return scnprintf(page, PAGE_SIZE, "%u\n", grp->num_pg);
+	} else if (strcmp(attr->name, "page_size") == 0) {
+		return scnprintf(page, PAGE_SIZE, "%u\n", grp->fpg_sz);
+	} else if (strcmp(attr->name, "hw_sector_size") == 0) {
+		return scnprintf(page, PAGE_SIZE, "%u\n", grp->csecs);
+	} else if (strcmp(attr->name, "oob_sector_size") == 0) {/* u32 */
+		return scnprintf(page, PAGE_SIZE, "%u\n", grp->sos);
+	} else if (strcmp(attr->name, "read_typ") == 0) {
+		return scnprintf(page, PAGE_SIZE, "%u\n", grp->trdt);
+	} else if (strcmp(attr->name, "read_max") == 0) {
+		return scnprintf(page, PAGE_SIZE, "%u\n", grp->trdm);
+	} else if (strcmp(attr->name, "prog_typ") == 0) {
+		return scnprintf(page, PAGE_SIZE, "%u\n", grp->tprt);
+	} else if (strcmp(attr->name, "prog_max") == 0) {
+		return scnprintf(page, PAGE_SIZE, "%u\n", grp->tprm);
+	} else if (strcmp(attr->name, "erase_typ") == 0) {
+		return scnprintf(page, PAGE_SIZE, "%u\n", grp->tbet);
+	} else if (strcmp(attr->name, "erase_max") == 0) {
+		return scnprintf(page, PAGE_SIZE, "%u\n", grp->tbem);
+	} else if (strcmp(attr->name, "multiplane_modes") == 0) {
+		return scnprintf(page, PAGE_SIZE, "0x%08x\n", grp->mpos);
+	} else if (strcmp(attr->name, "media_capabilities") == 0) {
+		return scnprintf(page, PAGE_SIZE, "0x%08x\n", grp->mccap);
+	} else if (strcmp(attr->name, "max_phys_secs") == 0) {
+		return scnprintf(page, PAGE_SIZE, "%u\n",
+				ndev->ops->max_phys_sect);
+	} else {
+		return scnprintf(page,
+				 PAGE_SIZE,
+				 "Unhandled attr(%s) in `nvm_dev_attr_show`\n",
+				 attr->name);
+	}
+}
+
+#define NVM_DEV_ATTR_RO(_name)						\
+	DEVICE_ATTR(_name, S_IRUGO, nvm_dev_attr_show, NULL)
+
+static NVM_DEV_ATTR_RO(version);
+static NVM_DEV_ATTR_RO(vendor_opcode);
+static NVM_DEV_ATTR_RO(capabilities);
+static NVM_DEV_ATTR_RO(device_mode);
+static NVM_DEV_ATTR_RO(ppa_format);
+static NVM_DEV_ATTR_RO(media_manager);
+
+static NVM_DEV_ATTR_RO(media_type);
+static NVM_DEV_ATTR_RO(flash_media_type);
+static NVM_DEV_ATTR_RO(num_channels);
+static NVM_DEV_ATTR_RO(num_luns);
+static NVM_DEV_ATTR_RO(num_planes);
+static NVM_DEV_ATTR_RO(num_blocks);
+static NVM_DEV_ATTR_RO(num_pages);
+static NVM_DEV_ATTR_RO(page_size);
+static NVM_DEV_ATTR_RO(hw_sector_size);
+static NVM_DEV_ATTR_RO(oob_sector_size);
+static NVM_DEV_ATTR_RO(read_typ);
+static NVM_DEV_ATTR_RO(read_max);
+static NVM_DEV_ATTR_RO(prog_typ);
+static NVM_DEV_ATTR_RO(prog_max);
+static NVM_DEV_ATTR_RO(erase_typ);
+static NVM_DEV_ATTR_RO(erase_max);
+static NVM_DEV_ATTR_RO(multiplane_modes);
+static NVM_DEV_ATTR_RO(media_capabilities);
+static NVM_DEV_ATTR_RO(max_phys_secs);
+
+#define NVM_DEV_ATTR(_name) (dev_attr_##_name##)
+
+static struct attribute *nvm_dev_attrs[] = {
+	&dev_attr_version.attr,
+	&dev_attr_vendor_opcode.attr,
+	&dev_attr_capabilities.attr,
+	&dev_attr_device_mode.attr,
+	&dev_attr_media_manager.attr,
+
+	&dev_attr_ppa_format.attr,
+	&dev_attr_media_type.attr,
+	&dev_attr_flash_media_type.attr,
+	&dev_attr_num_channels.attr,
+	&dev_attr_num_luns.attr,
+	&dev_attr_num_planes.attr,
+	&dev_attr_num_blocks.attr,
+	&dev_attr_num_pages.attr,
+	&dev_attr_page_size.attr,
+	&dev_attr_hw_sector_size.attr,
+	&dev_attr_oob_sector_size.attr,
+	&dev_attr_read_typ.attr,
+	&dev_attr_read_max.attr,
+	&dev_attr_prog_typ.attr,
+	&dev_attr_prog_max.attr,
+	&dev_attr_erase_typ.attr,
+	&dev_attr_erase_max.attr,
+	&dev_attr_multiplane_modes.attr,
+	&dev_attr_media_capabilities.attr,
+	&dev_attr_max_phys_secs.attr,
+	NULL,
+};
+
+static struct attribute_group nvm_dev_attr_group = {
+	.name = "lightnvm",
+	.attrs = nvm_dev_attrs,
+};
+
+static const struct attribute_group *nvm_dev_attr_groups[] = {
+	&nvm_dev_attr_group,
+	NULL,
+};
+
+static void nvm_dev_release(struct device *device)
+{
+	struct nvm_dev *dev = container_of(device, struct nvm_dev, dev);
+	struct request_queue *q = dev->q;
+
+	pr_debug("nvm/sysfs: `nvm_dev_release`\n");
+
+	blk_mq_unregister_dev(device, q);
+
+	nvm_free(dev);
+}
+
+static struct device_type nvm_type = {
+	.name		= "lightnvm",
+	.groups		= nvm_dev_attr_groups,
+	.release	= nvm_dev_release,
+};
+
+int nvm_sysfs_register_dev(struct nvm_dev *dev)
+{
+	if (!dev->parent_dev)
+		return 0;
+
+	dev->dev.parent = dev->parent_dev;
+	dev_set_name(&dev->dev, "%s", dev->name);
+	dev->dev.type = &nvm_type;
+	device_initialize(&dev->dev);
+	device_add(&dev->dev);
+
+	blk_mq_register_dev(&dev->dev, dev->q);
+
+	return 0;
+}
+
+void nvm_sysfs_unregister_dev(struct nvm_dev *dev)
+{
+	if (dev && dev->parent_dev)
+		kobject_put(&dev->dev.kobj);
+}