[PATCH v2 3/6] drivers: nvme: Implement flush command

[dmukhin at ford.com]

From: Denis Mukhin <dmukhin at ford.com> 

Implement the NVM flush command (opcode 0x00) to allow callers to
synchronize any buffered data with the backing NVMe storage.

Signed-off-by: Denis Mukhin <dmukhin at ford.com>
---
Changes since v1:
- moved generic disk_blk_flush() to a separate patch
---
 drivers/nvme/nvme.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/nvme/nvme.c b/drivers/nvme/nvme.c
index c3c44e50f19a..d9f099a11593 100644
--- a/drivers/nvme/nvme.c
+++ b/drivers/nvme/nvme.c
@@ -819,9 +819,29 @@ static ulong nvme_blk_write(struct udevice *udev, lbaint_t blknr,
 	return nvme_blk_rw(udev, blknr, blkcnt, (void *)buffer, false);
 }
 
+/*
+ * NVM Flush command (opcode 0x00).
+ *
+ * Applies to a single namespace; the controller must commit all dirty
+ * data for that namespace to storage before completing the command.
+ */
+static ulong nvme_blk_flush(struct udevice *udev)
+{
+	struct nvme_ns *ns = dev_get_priv(udev);
+	struct nvme_dev *dev = ns->dev;
+	struct nvme_command c;
+
+	memset(&c, 0, sizeof(c));
+	c.common.opcode = nvme_cmd_flush;
+	c.common.nsid = cpu_to_le32(ns->ns_id);
+
+	return nvme_submit_sync_cmd(dev->queues[NVME_IO_Q], &c, NULL, IO_TIMEOUT);
+}
+
 static const struct blk_ops nvme_blk_ops = {
 	.read	= nvme_blk_read,
 	.write	= nvme_blk_write,
+	.flush	= nvme_blk_flush,
 };
 
 U_BOOT_DRIVER(nvme_blk) = {
-- 
2.54.0