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, 14 insertions, 6 deletions

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;