[PATCH v4 16/31] firmware: arm_scmi: Add common per-protocol debugfs support
Cristian Marussi
cristian.marussi at arm.com
Fri Jun 12 15:37:46 PDT 2026
Allow interested SCMI protocols to register their own specific debugfs
entries under a common per-instance and per-protocol subtree rooted
at /sys/kernel/debug/scmi/<N>/protocols/<PROTO_ID>/
Expose a helper to enable protocol initialization code to get access to
such per-protocol/per-instance dentries in order to be able to install
their own dedicated debugfs entries.
Per-protocol debugfs support is configurable and default off.
Signed-off-by: Cristian Marussi <cristian.marussi at arm.com>
---
drivers/firmware/arm_scmi/Kconfig | 14 +++++++++++++
drivers/firmware/arm_scmi/common.h | 2 ++
drivers/firmware/arm_scmi/driver.c | 29 +++++++++++++++++++++++++++
drivers/firmware/arm_scmi/protocols.h | 6 ++++++
include/linux/scmi_protocol.h | 12 ++++++++++-
5 files changed, 62 insertions(+), 1 deletion(-)
diff --git a/drivers/firmware/arm_scmi/Kconfig b/drivers/firmware/arm_scmi/Kconfig
index e3fb36825978..06d2319420a0 100644
--- a/drivers/firmware/arm_scmi/Kconfig
+++ b/drivers/firmware/arm_scmi/Kconfig
@@ -69,6 +69,20 @@ config ARM_SCMI_DEBUG_COUNTERS
such useful debug counters. This can be helpful for debugging and
SCMI monitoring.
+config ARM_SCMI_DEBUG_PROTOCOLS
+ bool "Enable SCMI protocols debug"
+ select ARM_SCMI_NEED_DEBUGFS
+ depends on DEBUG_FS
+ default n
+ help
+ Enables per-protocol specific debug features, where available.
+ When provided, such per-protocol debugfs entries are grouped
+ inside a common a subtree named by the protocol number and rooted
+ under a per-instance 'protocols' directory.
+
+ Such per-protocol entries subtree structure is freely defined
+ within the related protocol code.
+
config ARM_SCMI_QUIRKS
bool "Enable SCMI Quirks framework"
depends on JUMP_LABEL || COMPILE_TEST
diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
index a8a45bacfa3f..79fda80f049a 100644
--- a/drivers/firmware/arm_scmi/common.h
+++ b/drivers/firmware/arm_scmi/common.h
@@ -321,6 +321,7 @@ enum debug_counters {
/**
* struct scmi_debug_info - Debug common info
* @top_dentry: A reference to the top debugfs dentry
+ * @protos: A reference to the top debugfs protocols subdirectory
* @name: Name of this SCMI instance
* @type: Type of this SCMI instance
* @is_atomic: Flag to state if the transport of this instance is atomic
@@ -328,6 +329,7 @@ enum debug_counters {
*/
struct scmi_debug_info {
struct dentry *top_dentry;
+ struct dentry *protos;
const char *name;
const char *type;
bool is_atomic;
diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index dd9446b54858..e844f40b19d9 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -18,6 +18,7 @@
#include <linux/bitmap.h>
#include <linux/cleanup.h>
+#include <linux/dcache.h>
#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/export.h>
@@ -99,6 +100,8 @@ struct scmi_xfers_info {
* has completed.
* @ph: An embedded protocol handle that will be passed down to protocol
* initialization code to identify this instance.
+ * @dbg: An optional reference to this protocol top debugfs directory; it will
+ * be automatically recursively removed on protocol de-initialization.
*
* Each protocol is initialized independently once for each SCMI platform in
* which is defined by DT and implemented by the SCMI server fw.
@@ -112,6 +115,7 @@ struct scmi_protocol_instance {
unsigned int version;
unsigned int negotiated_version;
struct scmi_protocol_handle ph;
+ struct dentry *dbg;
};
#define ph_to_pi(h) container_of(h, struct scmi_protocol_instance, ph)
@@ -2054,6 +2058,25 @@ static void scmi_common_fastchannel_db_ring(struct scmi_fc_db_info *db)
SCMI_PROTO_FC_RING_DB(64);
}
+static struct dentry *
+scmi_debugfs_proto_dentry_get(const struct scmi_protocol_handle *ph)
+{
+ struct scmi_protocol_instance *pi = ph_to_pi(ph);
+ struct scmi_info *info = handle_to_scmi_info(pi->handle);
+
+ if (!IS_ENABLED(CONFIG_ARM_SCMI_DEBUG_PROTOCOLS))
+ return ERR_PTR(-ENODEV);
+
+ if (!pi->dbg) {
+ char proto_dir[8];
+
+ snprintf(proto_dir, 8, "0x%02X", pi->proto->id);
+ pi->dbg = debugfs_create_dir(proto_dir, info->dbg->protos);
+ }
+
+ return pi->dbg;
+}
+
static const struct scmi_proto_helpers_ops helpers_ops = {
.extended_name_get = scmi_common_extended_name_get,
.get_max_msg_size = scmi_common_get_max_msg_size,
@@ -2062,6 +2085,7 @@ static const struct scmi_proto_helpers_ops helpers_ops = {
.protocol_msg_check = scmi_protocol_msg_check,
.fastchannel_init = scmi_common_fastchannel_init,
.fastchannel_db_ring = scmi_common_fastchannel_db_ring,
+ .debugfs_proto_dentry_get = scmi_debugfs_proto_dentry_get,
};
/**
@@ -2356,6 +2380,8 @@ void scmi_protocol_release(const struct scmi_handle *handle, u8 protocol_id)
if (refcount_dec_and_test(&pi->users)) {
void *gid = pi->gid;
+ debugfs_remove_recursive(pi->dbg);
+
if (pi->proto->events)
scmi_deregister_protocol_events(handle, protocol_id);
@@ -3080,6 +3106,9 @@ static struct scmi_debug_info *scmi_debugfs_common_setup(struct scmi_info *info)
if (IS_ENABLED(CONFIG_ARM_SCMI_DEBUG_COUNTERS))
scmi_debugfs_counters_setup(dbg, trans);
+ if (IS_ENABLED(CONFIG_ARM_SCMI_DEBUG_PROTOCOLS))
+ dbg->protos = debugfs_create_dir("protocols", top_dentry);
+
dbg->top_dentry = top_dentry;
if (devm_add_action_or_reset(info->dev,
diff --git a/drivers/firmware/arm_scmi/protocols.h b/drivers/firmware/arm_scmi/protocols.h
index 3250d981664b..84ffff9376c9 100644
--- a/drivers/firmware/arm_scmi/protocols.h
+++ b/drivers/firmware/arm_scmi/protocols.h
@@ -11,6 +11,7 @@
#include <linux/bitfield.h>
#include <linux/completion.h>
+#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/kernel.h>
@@ -272,6 +273,9 @@ struct scmi_fc_info {
* gathering FC descriptions from the SCMI platform server.
* @fastchannel_db_ring: A common helper to ring a FC doorbell.
* @get_max_msg_size: A common helper to get the maximum message size.
+ * @debugfs_proto_dentry_get: A common helper to get a per-protocol debugfs top
+ * directory to use as a root. It will be
+ * recursively removed on protocol de-initialization.
*/
struct scmi_proto_helpers_ops {
int (*extended_name_get)(const struct scmi_protocol_handle *ph,
@@ -292,6 +296,8 @@ struct scmi_proto_helpers_ops {
u32 *rate_limit);
void (*fastchannel_db_ring)(struct scmi_fc_db_info *db);
int (*get_max_msg_size)(const struct scmi_protocol_handle *ph);
+ struct dentry *(*debugfs_proto_dentry_get)
+ (const struct scmi_protocol_handle *ph);
};
/**
diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
index c7e8a740ce16..6b0ea1c05e7f 100644
--- a/include/linux/scmi_protocol.h
+++ b/include/linux/scmi_protocol.h
@@ -1076,6 +1076,12 @@ struct scmi_notify_ops {
* never sleep and act accordingly.
* An optional atomic threshold value could be returned
* where configured.
+ * @debugfs_entry_get: method to get, and possibly create, a debugfs dentry
+ * rooted under the top debugfs directory for the SCMI
+ * instance referred by handle.
+ * @debugfs_entry_put: method to put, and possibly destroy, a debugfs dentry
+ * rooted under the top debugfs directory for the SCMI
+ * instance referred by handle.
* @notify_ops: pointer to set of notifications related operations
*/
struct scmi_handle {
@@ -1090,7 +1096,11 @@ struct scmi_handle {
void (*devm_protocol_put)(struct scmi_device *sdev, u8 proto);
bool (*is_transport_atomic)(const struct scmi_handle *handle,
unsigned int *atomic_threshold);
-
+ struct dentry __must_check *
+ (*debugfs_entry_get)(const struct scmi_handle *handle,
+ const char *name);
+ void (*debugfs_entry_put)(const struct scmi_handle *handle,
+ struct dentry *dentry);
const struct scmi_notify_ops *notify_ops;
};
--
2.54.0
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