nvme: use nvme_wait_ready in nvme_shutdown_ctrl

Refactor the code to wait for CSTS state changes so that it can be reused
by nvme_shutdown_ctrl.  This reduces the delay between each iteration
that checks CSTS from 100ms in the shutdown code to the 1 to 2ms range
done during enable, matching the changes from commit 3e98c244 that
were only applied to the enable/disable path.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Pankaj Raghav <p.raghav@samsung.com>

drivers/nvme/host/core.c

@@ -2252,16 +2252,17 @@ static const struct block_device_operations nvme_bdev_ops = {
 	.pr_ops		= &nvme_pr_ops,
 };
 
-static int nvme_wait_ready(struct nvme_ctrl *ctrl, u32 timeout, bool enabled)
+static int nvme_wait_ready(struct nvme_ctrl *ctrl, u32 mask, u32 val,
+		u32 timeout, const char *op)
 {
-	unsigned long timeout_jiffies = ((timeout + 1) * HZ / 2) + jiffies;
-	u32 csts, bit = enabled ? NVME_CSTS_RDY : 0;
+	unsigned long timeout_jiffies = jiffies + timeout * HZ;
+	u32 csts;
 	int ret;
 
 	while ((ret = ctrl->ops->reg_read32(ctrl, NVME_REG_CSTS, &csts)) == 0) {
 		if (csts == ~0)
 			return -ENODEV;
-		if ((csts & NVME_CSTS_RDY) == bit)
+		if ((csts & mask) == val)
 			break;
 
 		usleep_range(1000, 2000);
@@ -2270,7 +2271,7 @@ static int nvme_wait_ready(struct nvme_ctrl *ctrl, u32 timeout, bool enabled)
 		if (time_after(jiffies, timeout_jiffies)) {
 			dev_err(ctrl->device,
 				"Device not ready; aborting %s, CSTS=0x%x\n",
-				enabled ? "initialisation" : "reset", csts);
+				op, csts);
 			return -ENODEV;
 		}
 	}
@@ -2297,8 +2298,8 @@ int nvme_disable_ctrl(struct nvme_ctrl *ctrl)
 
 	if (ctrl->quirks & NVME_QUIRK_DELAY_BEFORE_CHK_RDY)
 		msleep(NVME_QUIRK_DELAY_AMOUNT);
-
-	return nvme_wait_ready(ctrl, NVME_CAP_TIMEOUT(ctrl->cap), false);
+	return nvme_wait_ready(ctrl, NVME_CSTS_RDY, 0,
+			       (NVME_CAP_TIMEOUT(ctrl->cap) + 1) / 2, "reset");
 }
 EXPORT_SYMBOL_GPL(nvme_disable_ctrl);
 
@@ -2363,14 +2364,13 @@ int nvme_enable_ctrl(struct nvme_ctrl *ctrl)
 	ret = ctrl->ops->reg_write32(ctrl, NVME_REG_CC, ctrl->ctrl_config);
 	if (ret)
 		return ret;
-	return nvme_wait_ready(ctrl, timeout, true);
+	return nvme_wait_ready(ctrl, NVME_CSTS_RDY, NVME_CSTS_RDY,
+			       (timeout + 1) / 2, "initialisation");
 }
 EXPORT_SYMBOL_GPL(nvme_enable_ctrl);
 
 int nvme_shutdown_ctrl(struct nvme_ctrl *ctrl)
 {
-	unsigned long timeout = jiffies + (ctrl->shutdown_timeout * HZ);
-	u32 csts;
 	int ret;
 
 	ctrl->ctrl_config &= ~NVME_CC_SHN_MASK;
@@ -2379,22 +2379,8 @@ int nvme_shutdown_ctrl(struct nvme_ctrl *ctrl)
 	ret = ctrl->ops->reg_write32(ctrl, NVME_REG_CC, ctrl->ctrl_config);
 	if (ret)
 		return ret;
-
-	while ((ret = ctrl->ops->reg_read32(ctrl, NVME_REG_CSTS, &csts)) == 0) {
-		if ((csts & NVME_CSTS_SHST_MASK) == NVME_CSTS_SHST_CMPLT)
-			break;
-
-		msleep(100);
-		if (fatal_signal_pending(current))
-			return -EINTR;
-		if (time_after(jiffies, timeout)) {
-			dev_err(ctrl->device,
-				"Device shutdown incomplete; abort shutdown\n");
-			return -ENODEV;
-		}
-	}
-
-	return ret;
+	return nvme_wait_ready(ctrl, NVME_CSTS_SHST_MASK, NVME_CSTS_SHST_CMPLT,
+			       ctrl->shutdown_timeout, "shutdown");
 }
 EXPORT_SYMBOL_GPL(nvme_shutdown_ctrl);