NVMe: Add nvme subsystem reset IOCTL

Controllers can perform optional subsystem resets as introduced in NVMe
1.1. This patch adds an IOCTL to trigger the subsystem reset by writing
"NVMe" to the NSSR register.

Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
index e318a99..3a35c58 100644 (file)
--- a/drivers/block/nvme-core.c
+++ b/drivers/block/nvme-core.c
@@ -1901,6 +1901,15 @@ static int nvme_user_cmd(struct nvme_dev *dev, struct nvme_ns *ns,
        return status;
 }
 
+static int nvme_subsys_reset(struct nvme_dev *dev)
+{
+       if (!dev->subsystem)
+               return -ENOTTY;
+
+       writel(0x4E564D65, &dev->bar->nssr); /* "NVMe" */
+       return 0;
+}
+
 static int nvme_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd,
                                                        unsigned long arg)
 {
@@ -2932,6 +2941,8 @@ static long nvme_dev_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
        case NVME_IOCTL_RESET:
                dev_warn(dev->dev, "resetting controller\n");
                return nvme_reset(dev);
+       case NVME_IOCTL_SUBSYS_RESET:
+               return nvme_subsys_reset(dev);
        default:
                return -ENOTTY;
        }

diff --git a/include/linux/nvme.h b/include/linux/nvme.h
index d6b5600..b5812c3 100644 (file)
--- a/include/linux/nvme.h
+++ b/include/linux/nvme.h
@@ -28,7 +28,7 @@ struct nvme_bar {
        __u32                   cc;     /* Controller Configuration */
        __u32                   rsvd1;  /* Reserved */
        __u32                   csts;   /* Controller Status */
-       __u32                   rsvd2;  /* Reserved */
+       __u32                   nssr;   /* Subsystem Reset */
        __u32                   aqa;    /* Admin Queue Attributes */
        __u64                   asq;    /* Admin SQ Base Address */
        __u64                   acq;    /* Admin CQ Base Address */

diff --git a/include/uapi/linux/nvme.h b/include/uapi/linux/nvme.h
index 732b32e..8864194 100644 (file)
--- a/include/uapi/linux/nvme.h
+++ b/include/uapi/linux/nvme.h
@@ -584,5 +584,6 @@ struct nvme_passthru_cmd {
 #define NVME_IOCTL_SUBMIT_IO   _IOW('N', 0x42, struct nvme_user_io)
 #define NVME_IOCTL_IO_CMD      _IOWR('N', 0x43, struct nvme_passthru_cmd)
 #define NVME_IOCTL_RESET       _IO('N', 0x44)
+#define NVME_IOCTL_SUBSYS_RESET        _IO('N', 0x45)
 
 #endif /* _UAPI_LINUX_NVME_H */