[PATCH 3/3] nvme: add per-controller sysfs interface for APST configuration

[Yaxiong Tian]

From: Yaxiong Tian <tianyaxiong@xxxxxxxxxx>

Currently, APST (Autonomous Power State Transition) parameters are
configured as module parameters affecting all controllers uniformly,
 This lacks flexibility for heterogeneous systems.

This patch introduces per-controller sysfs attributes under each NVMe
controller's sysfs directory:
- apst_primary_timeout_ms
- apst_secondary_timeout_ms
- apst_primary_latency_tol_us
- apst_secondary_latency_tol_us

The attributes allow runtime configuration of:
1. Timeout values for primary/secondary states
2. Latency tolerance requirements

The existing module parameters are retained for backward compatibility
but now only serve as default values for new controllers.

Signed-off-by: Yaxiong Tian <tianyaxiong@xxxxxxxxxx>
---
 drivers/nvme/host/core.c  | 16 ++++++++++------
 drivers/nvme/host/nvme.h  |  4 ++++
 drivers/nvme/host/sysfs.c | 36 ++++++++++++++++++++++++++++++++++++
 3 files changed, 50 insertions(+), 6 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index cfce433c5553..812e0a1f3b53 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2608,22 +2608,22 @@ static int nvme_configure_host_options(struct nvme_ctrl *ctrl)
  * timeout value is returned and the matching tolerance index (1 or 2) is
  * reported.
  */
-static bool nvme_apst_get_transition_time(u64 total_latency,
+static bool nvme_apst_get_transition_time(struct nvme_ctrl *ctrl, u64 total_latency,
 		u64 *transition_time, unsigned *last_index)
 {
-	if (total_latency <= apst_primary_latency_tol_us) {
+	if (total_latency <= ctrl->apst_primary_latency_tol_us) {
 		if (*last_index == 1)
 			return false;
 		*last_index = 1;
-		*transition_time = apst_primary_timeout_ms;
+		*transition_time = ctrl->apst_primary_timeout_ms;
 		return true;
 	}
 	if (apst_secondary_timeout_ms &&
-		total_latency <= apst_secondary_latency_tol_us) {
+		total_latency <= ctrl->apst_secondary_latency_tol_us) {
 		if (*last_index <= 2)
 			return false;
 		*last_index = 2;
-		*transition_time = apst_secondary_timeout_ms;
+		*transition_time = ctrl->apst_secondary_timeout_ms;
 		return true;
 	}
 	return false;
@@ -2728,7 +2728,7 @@ int nvme_configure_apst(struct nvme_ctrl *ctrl)
 		 * for higher power states.
 		 */
 		if (apst_primary_timeout_ms && apst_primary_latency_tol_us) {
-			if (!nvme_apst_get_transition_time(total_latency_us,
+			if (!nvme_apst_get_transition_time(ctrl, total_latency_us,
 					&transition_ms, &last_lt_index))
 				continue;
 		} else {
@@ -4853,6 +4853,10 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct device *dev,
 	ctrl->ka_last_check_time = jiffies;
 
 	mutex_init(&ctrl->apst_lock);
+	ctrl->apst_primary_timeout_ms = apst_primary_timeout_ms;
+	ctrl->apst_secondary_timeout_ms = apst_secondary_timeout_ms;
+	ctrl->apst_primary_latency_tol_us = apst_primary_latency_tol_us;
+	ctrl->apst_secondary_latency_tol_us = apst_secondary_latency_tol_us;
 
 	BUILD_BUG_ON(NVME_DSM_MAX_RANGES * sizeof(struct nvme_dsm_range) >
 			PAGE_SIZE);
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 7f8e10f5bf7a..ed9afc3c6781 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -387,6 +387,10 @@ struct nvme_ctrl {
 	/* Power saving configuration */
 	struct mutex apst_lock;
 	u64 ps_max_latency_us;
+	u64 apst_primary_timeout_ms;
+	u64 apst_secondary_timeout_ms;
+	u64 apst_primary_latency_tol_us;
+	u64 apst_secondary_latency_tol_us;
 	bool apst_enabled;
 
 	/* PCIe only: */
diff --git a/drivers/nvme/host/sysfs.c b/drivers/nvme/host/sysfs.c
index 5003cb294d65..afa61e9c1366 100644
--- a/drivers/nvme/host/sysfs.c
+++ b/drivers/nvme/host/sysfs.c
@@ -684,6 +684,37 @@ static DEVICE_ATTR(dhchap_ctrl_secret, S_IRUGO | S_IWUSR,
 	nvme_ctrl_dhchap_ctrl_secret_show, nvme_ctrl_dhchap_ctrl_secret_store);
 #endif
 
+#define nvme_apst_show_and_store_function(field)				\
+static ssize_t field##_show(struct device *dev,		\
+			    struct device_attribute *attr, char *buf)	\
+{									\
+	struct nvme_ctrl *ctrl = dev_get_drvdata(dev);			\
+	return sysfs_emit(buf, "%llu\n", ctrl->field);	\
+}									\
+									\
+static ssize_t field##_store(struct device *dev,		\
+			     struct device_attribute *attr,		\
+			     const char *buf, size_t size)		\
+{									\
+	int err;						\
+	u64 data = 0;					\
+	struct nvme_ctrl *ctrl = dev_get_drvdata(dev);			\
+	err = kstrtou64(buf, 0, &data);		\
+	if (err < 0)						\
+		return err;						\
+							\
+	mutex_lock(&ctrl->apst_lock);		\
+	ctrl->field = data; 	\
+	mutex_unlock(&ctrl->apst_lock);		\
+	return size;			\
+}									\
+static DEVICE_ATTR_RW(field);
+
+nvme_apst_show_and_store_function(apst_primary_timeout_ms);
+nvme_apst_show_and_store_function(apst_secondary_timeout_ms);
+nvme_apst_show_and_store_function(apst_primary_latency_tol_us);
+nvme_apst_show_and_store_function(apst_secondary_latency_tol_us);
+
 static ssize_t apst_update_store(struct device *dev,
 					      struct device_attribute *attr,
 					      const char *buf, size_t size)
@@ -734,6 +765,11 @@ static struct attribute *nvme_dev_attrs[] = {
 	&dev_attr_dhchap_ctrl_secret.attr,
 #endif
 	&dev_attr_adm_passthru_err_log_enabled.attr,
+
+	&dev_attr_apst_primary_timeout_ms.attr,
+	&dev_attr_apst_secondary_timeout_ms.attr,
+	&dev_attr_apst_primary_latency_tol_us.attr,
+	&dev_attr_apst_secondary_latency_tol_us.attr,
 	&dev_attr_apst_update.attr,
 	NULL
 };
-- 
2.25.1