[PATCH v4 15/31] firmware: arm_scmi: Add Telemetry generation counter

[Cristian Marussi]

Add a per-instance generation counter to track configuration changes and
expose a telemetry operations to get a related waitqueue for monitoring.

Signed-off-by: Cristian Marussi <cristian.marussi at arm.com>
---
 drivers/firmware/arm_scmi/telemetry.c | 53 +++++++++++++++++++++++++++
 include/linux/scmi_protocol.h         |  5 +++
 2 files changed, 58 insertions(+)

diff --git a/drivers/firmware/arm_scmi/telemetry.c b/drivers/firmware/arm_scmi/telemetry.c
index 842b0fa4f07d..ab1be6c462f1 100644
--- a/drivers/firmware/arm_scmi/telemetry.c
+++ b/drivers/firmware/arm_scmi/telemetry.c
@@ -21,6 +21,7 @@
 #include <linux/sprintf.h>
 #include <linux/string.h>
 #include <linux/xarray.h>
+#include <linux/wait.h>
 
 #include "protocols.h"
 #include "notify.h"
@@ -30,6 +31,7 @@
 /* Updated only after ALL the mandatory features for that version are merged */
 #define SCMI_PROTOCOL_SUPPORTED_VERSION		0x10000
 
+#define SCMI_TLM_GENERATION_ONE		(SCMI_TLM_GENERATION_INVALID + 1U)
 #define SCMI_TLM_TDCF_MAX_RETRIES	5
 
 enum scmi_telemetry_protocol_cmd {
@@ -464,6 +466,7 @@ struct telemetry_info {
 	struct list_head free_des;
 	struct list_head fcs_des;
 	struct scmi_telemetry_info info;
+	struct wait_queue_head gen_wq;
 	struct notifier_block telemetry_nb;
 	atomic_t rinfo_initializing;
 	struct completion rinfo_initdone;
@@ -613,6 +616,29 @@ scmi_telemetry_tde_cache_lookup(struct telemetry_de *tde,
 	return 0;
 }
 
+static inline void __scmi_telemetry_generation_set(struct telemetry_info *ti,
+						   unsigned int new)
+{
+	atomic_set(&ti->info.generation, new);
+
+	wake_up_all(&ti->gen_wq);
+}
+
+static inline void scmi_telemetry_generation_update(struct telemetry_info *ti)
+{
+	unsigned int next;
+
+	/* Wrap around skipping invalid generation 0 */
+	next = (atomic_read(&ti->info.generation) + 1) ?: SCMI_TLM_GENERATION_ONE;
+
+	__scmi_telemetry_generation_set(ti, next);
+}
+
+static inline void scmi_telemetry_generation_reset(struct telemetry_info *ti)
+{
+	__scmi_telemetry_generation_set(ti, SCMI_TLM_GENERATION_ONE);
+}
+
 struct scmi_tlm_de_priv {
 	struct telemetry_info *ti;
 	void *next;
@@ -2084,6 +2110,8 @@ static int __scmi_telemetry_state_set(const struct scmi_protocol_handle *ph,
 						       tstamp_enabled_state,
 						       *tstamp);
 
+		/* A local change can have an impact anyway */
+		scmi_telemetry_generation_update(ti);
 		return 0;
 	}
 
@@ -2145,6 +2173,9 @@ static int __scmi_telemetry_state_set(const struct scmi_protocol_handle *ph,
 
 	ph->xops->xfer_put(ph, t);
 
+	if (!ret)
+		scmi_telemetry_generation_update(ti);
+
 	return ret;
 }
 
@@ -2248,6 +2279,9 @@ static int scmi_telemetry_all_disable(const struct scmi_protocol_handle *ph,
 
 	ph->xops->xfer_put(ph, t);
 
+	if (!ret)
+		scmi_telemetry_generation_update(ti);
+
 	return ret;
 }
 
@@ -2320,6 +2354,9 @@ scmi_telemetry_collection_configure(const struct scmi_protocol_handle *ph,
 
 	ph->xops->xfer_put(ph, t);
 
+	if (!ret)
+		scmi_telemetry_generation_update(ti);
+
 	return ret;
 }
 
@@ -2752,6 +2789,10 @@ static int scmi_telemetry_reset(const struct scmi_protocol_handle *ph)
 		struct telemetry_info *ti = ph->get_priv(ph);
 
 		scmi_telemetry_local_resources_reset(ti);
+
+		/* Reset generation now that server has been reset */
+		scmi_telemetry_generation_reset(ti);
+
 		/* Fetch again the states from platform. */
 		ret = scmi_telemetry_initial_state_lookup(ti);
 		if (ret)
@@ -2764,6 +2805,14 @@ static int scmi_telemetry_reset(const struct scmi_protocol_handle *ph)
 	return ret;
 }
 
+static struct wait_queue_head *
+scmi_telemetry_event_wq_get(const struct scmi_protocol_handle *ph)
+{
+	struct telemetry_info *ti = ph->get_priv(ph);
+
+	return &ti->gen_wq;
+}
+
 static const struct scmi_telemetry_proto_ops tlm_proto_ops = {
 	.info_get = scmi_telemetry_info_get,
 	.de_lookup = scmi_telemetry_de_lookup,
@@ -2776,6 +2825,7 @@ static const struct scmi_telemetry_proto_ops tlm_proto_ops = {
 	.des_bulk_read = scmi_telemetry_des_bulk_read,
 	.des_sample_get = scmi_telemetry_des_sample_get,
 	.reset = scmi_telemetry_reset,
+	.event_wq_get = scmi_telemetry_event_wq_get,
 };
 
 static bool
@@ -3066,6 +3116,9 @@ static int scmi_telemetry_instance_init(struct telemetry_info *ti)
 
 	xa_init(&ti->xa_des);
 	xa_init(&ti->xa_lines);
+	/* Generation counter init */
+	atomic_set(&ti->info.generation, SCMI_TLM_GENERATION_ONE);
+	init_waitqueue_head(&ti->gen_wq);
 	atomic_set(&ti->des_enabled[ENA_STATE], 0);
 	atomic_set(&ti->des_enabled[ENA_TSTAMP], 0);
 	/* Setup resources lazy initialization */
diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
index 568fb7bb1a76..c7e8a740ce16 100644
--- a/include/linux/scmi_protocol.h
+++ b/include/linux/scmi_protocol.h
@@ -13,6 +13,7 @@
 #include <linux/device.h>
 #include <linux/notifier.h>
 #include <linux/types.h>
+#include <linux/wait.h>
 
 #include <uapi/linux/limits.h>
 #include <uapi/linux/scmi.h>
@@ -889,6 +890,7 @@ enum scmi_telemetry_collection {
 	SCMI_TLM_SINGLE_READ,
 };
 
+#define SCMI_TLM_GENERATION_INVALID	0U
 #define SCMI_TLM_GRP_INVALID		0xFFFFFFFF
 struct scmi_telemetry_group {
 	bool enabled;
@@ -933,6 +935,7 @@ struct scmi_telemetry_info {
 	bool enabled;
 	bool notif_enabled;
 	enum scmi_telemetry_collection current_mode;
+	atomic_t generation;
 };
 
 struct scmi_telemetry_de_sample {
@@ -965,6 +968,7 @@ struct scmi_telemetry_de_sample {
  *		    This causes an immediate update platform-side of all the
  *		    enabled DEs.
  * @reset: reset configuration and telemetry data.
+ * @event_wq_get: get a reference to the event waitqueue for this instance.
  */
 struct scmi_telemetry_proto_ops {
 	const struct scmi_telemetry_info __must_check *(*info_get)
@@ -992,6 +996,7 @@ struct scmi_telemetry_proto_ops {
 					   int grp_id, int *num_samples,
 					   struct scmi_telemetry_de_sample *samples);
 	int (*reset)(const struct scmi_protocol_handle *ph);
+	struct wait_queue_head *(*event_wq_get)(const struct scmi_protocol_handle *ph);
 };
 
 /**
-- 
2.54.0