nvme: add support for NVMe 1.3 Timestamp Feature

NVME's Timestamp feature allows controllers to be aware of the epoch
time in milliseconds. This patch adds the set features hook for various
transports through the identify path, so that resets and resumes can
update the controller as necessary.
Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
[hch: rebased on top of nvme-4.13 error handling changes,
      changed nvme_configure_timestamp to return the status]
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/host/core.c

@@ -1507,6 +1507,23 @@ static void nvme_set_queue_limits(struct nvme_ctrl *ctrl,
 	blk_queue_write_cache(q, vwc, vwc);
 }
 
+static int nvme_configure_timestamp(struct nvme_ctrl *ctrl)
+{
+	__le64 ts;
+	int ret;
+
+	if (!(ctrl->oncs & NVME_CTRL_ONCS_TIMESTAMP))
+		return 0;
+
+	ts = cpu_to_le64(ktime_to_ms(ktime_get_real()));
+	ret = nvme_set_features(ctrl, NVME_FEAT_TIMESTAMP, 0, &ts, sizeof(ts),
+			NULL);
+	if (ret)
+		dev_warn_once(ctrl->device,
+			"could not set timestamp (%d)\n", ret);
+	return ret;
+}
+
 static int nvme_configure_apst(struct nvme_ctrl *ctrl)
 {
 	/*
@@ -1862,6 +1879,10 @@ int nvme_init_identify(struct nvme_ctrl *ctrl)
 	if (ret < 0)
 		return ret;
 	
+	ret = nvme_configure_timestamp(ctrl);
+	if (ret < 0)
+		return ret;
+
 	ret = nvme_configure_directives(ctrl);
 	if (ret < 0)
 		return ret;

include/linux/nvme.h

@@ -254,6 +254,7 @@ enum {
 	NVME_CTRL_ONCS_WRITE_UNCORRECTABLE	= 1 << 1,
 	NVME_CTRL_ONCS_DSM			= 1 << 2,
 	NVME_CTRL_ONCS_WRITE_ZEROES		= 1 << 3,
+	NVME_CTRL_ONCS_TIMESTAMP		= 1 << 6,
 	NVME_CTRL_VWC_PRESENT			= 1 << 0,
 	NVME_CTRL_OACS_SEC_SUPP                 = 1 << 0,
 	NVME_CTRL_OACS_DIRECTIVES		= 1 << 5,
@@ -688,6 +689,7 @@ enum {
 	NVME_FEAT_ASYNC_EVENT	= 0x0b,
 	NVME_FEAT_AUTO_PST	= 0x0c,
 	NVME_FEAT_HOST_MEM_BUF	= 0x0d,
+	NVME_FEAT_TIMESTAMP	= 0x0e,
 	NVME_FEAT_KATO		= 0x0f,
 	NVME_FEAT_SW_PROGRESS	= 0x80,
 	NVME_FEAT_HOST_ID	= 0x81,