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>

1 files changed, 16 insertions, 2 deletions

diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index e0535c14e538..bfd25dd73bca 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -308,11 +308,21 @@ int nvme_sg_get_version_num(int __user *ip);
 
 #ifdef CONFIG_NVM
 int nvme_nvm_ns_supported(struct nvme_ns *ns, struct nvme_id_ns *id);
-int nvme_nvm_register(struct nvme_ns *ns, char *disk_name, int node);
+int nvme_nvm_register(struct nvme_ns *ns, char *disk_name, int node,
+		      const struct attribute_group *attrs);
 void nvme_nvm_unregister(struct nvme_ns *ns);
+
+static inline struct nvme_ns *nvme_get_ns_from_dev(struct device *dev)
+{
+	if (dev->type->devnode)
+		return dev_to_disk(dev)->private_data;
+
+	return (container_of(dev, struct nvm_dev, dev))->private_data;
+}
 #else
 static inline int nvme_nvm_register(struct nvme_ns *ns, char *disk_name,
-								int node)
+				    int node,
+				    const struct attribute_group *attrs)
 {
 	return 0;
 }
@@ -323,6 +333,10 @@ static inline int nvme_nvm_ns_supported(struct nvme_ns *ns, struct nvme_id_ns *i
 {
 	return 0;
 }
+static inline struct nvme_ns *nvme_get_ns_from_dev(struct device *dev)
+{
+	return dev_to_disk(dev)->private_data;
+}
 #endif /* CONFIG_NVM */
 
 int __init nvme_core_init(void);