PM: EM: Add dump to get-perf-domains in the EM YNL spec

Add dump to get-perf-domains, so that a user can fetch either information
about a specific performance domain with do or information about all
performance domains with dump. Share the reply format of do and dump using
perf-domain-attrs, so remove perf-domains. The YNL spec, autogenerated
files, and the do implementation are updated, and the dump implementation
is added.

Suggested-by: Donald Hunter <donald.hunter@gmail.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Signed-off-by: Changwoo Min <changwoo@igalia.com>
Link: https://patch.msgid.link/20260108053212.642478-5-changwoo@igalia.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Documentation/netlink/specs/dev-energymodel.yaml

@@ -42,16 +42,6 @@ definitions:
           missing real power information.
 
 attribute-sets:
-  -
-    name: perf-domains
-    doc: >-
-      Information on all the performance domains.
-    attributes:
-      -
-        name: perf-domain
-        type: nest
-        nested-attributes: perf-domain
-        multi-attr: true
   -
     name: perf-domain
     doc: >-
@@ -133,12 +123,21 @@ operations:
   list:
     -
       name: get-perf-domains
-      attribute-set: perf-domains
+      attribute-set: perf-domain
       doc: Get the list of information for all performance domains.
       do:
-        reply:
+        request:
           attributes:
-            - perf-domain
+            - perf-domain-id
+        reply:
+          attributes: &perf-domain-attrs
+            - pad
+            - perf-domain-id
+            - flags
+            - cpus
+      dump:
+        reply:
+          attributes: *perf-domain-attrs
     -
       name: get-perf-table
       attribute-set: perf-table

include/uapi/linux/dev_energymodel.h

@@ -36,13 +36,6 @@ enum dev_energymodel_perf_domain_flags {
 	DEV_ENERGYMODEL_PERF_DOMAIN_FLAGS_PERF_DOMAIN_ARTIFICIAL = 4,
 };
 
-enum {
-	DEV_ENERGYMODEL_A_PERF_DOMAINS_PERF_DOMAIN = 1,
-
-	__DEV_ENERGYMODEL_A_PERF_DOMAINS_MAX,
-	DEV_ENERGYMODEL_A_PERF_DOMAINS_MAX = (__DEV_ENERGYMODEL_A_PERF_DOMAINS_MAX - 1)
-};
-
 enum {
 	DEV_ENERGYMODEL_A_PERF_DOMAIN_PAD = 1,
 	DEV_ENERGYMODEL_A_PERF_DOMAIN_PERF_DOMAIN_ID,

kernel/power/em_netlink.c

@@ -18,6 +18,13 @@
 #include "em_netlink_autogen.h"
 
 /*************************** Command encoding ********************************/
+struct dump_ctx {
+	int idx;
+	int start;
+	struct sk_buff *skb;
+	struct netlink_callback *cb;
+};
+
 static int __em_nl_get_pd_size(struct em_perf_domain *pd, void *data)
 {
 	int nr_cpus, msg_sz, cpus_sz;
@@ -43,14 +50,8 @@ static int __em_nl_get_pd(struct em_perf_domain *pd, void *data)
 {
 	struct sk_buff *msg = data;
 	struct cpumask *cpumask;
-	struct nlattr *entry;
 	int cpu;
 
-	entry = nla_nest_start(msg,
-			       DEV_ENERGYMODEL_A_PERF_DOMAINS_PERF_DOMAIN);
-	if (!entry)
-		goto out_cancel_nest;
-
 	if (nla_put_u32(msg, DEV_ENERGYMODEL_A_PERF_DOMAIN_PERF_DOMAIN_ID,
 			pd->id))
 		goto out_cancel_nest;
@@ -66,26 +67,50 @@ static int __em_nl_get_pd(struct em_perf_domain *pd, void *data)
 			goto out_cancel_nest;
 	}
 
-	nla_nest_end(msg, entry);
-
 	return 0;
 
 out_cancel_nest:
-	nla_nest_cancel(msg, entry);
-
 	return -EMSGSIZE;
 }
 
+static int __em_nl_get_pd_for_dump(struct em_perf_domain *pd, void *data)
+{
+	const struct genl_info *info;
+	struct dump_ctx *ctx = data;
+	void *hdr;
+	int ret;
+
+	if (ctx->idx++ < ctx->start)
+		return 0;
+
+	info = genl_info_dump(ctx->cb);
+	hdr = genlmsg_iput(ctx->skb, info);
+	if (!hdr) {
+		genlmsg_cancel(ctx->skb, hdr);
+		return -EMSGSIZE;
+	}
+
+	ret = __em_nl_get_pd(pd, ctx->skb);
+	genlmsg_end(ctx->skb, hdr);
+	return ret;
+}
+
 int dev_energymodel_nl_get_perf_domains_doit(struct sk_buff *skb,
 					      struct genl_info *info)
 {
+	int id, ret = -EMSGSIZE, msg_sz = 0;
+	int cmd = info->genlhdr->cmd;
+	struct em_perf_domain *pd;
 	struct sk_buff *msg;
 	void *hdr;
-	int cmd = info->genlhdr->cmd;
-	int ret = -EMSGSIZE, msg_sz = 0;
 
-	for_each_em_perf_domain(__em_nl_get_pd_size, &msg_sz);
+	if (!info->attrs[DEV_ENERGYMODEL_A_PERF_DOMAIN_PERF_DOMAIN_ID])
+		return -EINVAL;
 
+	id = nla_get_u32(info->attrs[DEV_ENERGYMODEL_A_PERF_DOMAIN_PERF_DOMAIN_ID]);
+	pd = em_perf_domain_get_by_id(id);
+
+	__em_nl_get_pd_size(pd, &msg_sz);
 	msg = genlmsg_new(msg_sz, GFP_KERNEL);
 	if (!msg)
 		return -ENOMEM;
@@ -94,10 +119,9 @@ int dev_energymodel_nl_get_perf_domains_doit(struct sk_buff *skb,
 	if (!hdr)
 		goto out_free_msg;
 
-	ret = for_each_em_perf_domain(__em_nl_get_pd, msg);
+	ret = __em_nl_get_pd(pd, msg);
 	if (ret)
 		goto out_cancel_msg;
-
 	genlmsg_end(msg, hdr);
 
 	return genlmsg_reply(msg, info);
@@ -106,10 +130,22 @@ out_cancel_msg:
 	genlmsg_cancel(msg, hdr);
 out_free_msg:
 	nlmsg_free(msg);
-
 	return ret;
 }
 
+int dev_energymodel_nl_get_perf_domains_dumpit(struct sk_buff *skb,
+						struct netlink_callback *cb)
+{
+	struct dump_ctx ctx = {
+		.idx = 0,
+		.start = cb->args[0],
+		.skb = skb,
+		.cb = cb,
+	};
+
+	return for_each_em_perf_domain(__em_nl_get_pd_for_dump, &ctx);
+}
+
 static struct em_perf_domain *__em_nl_get_pd_table_id(struct nlattr **attrs)
 {
 	struct em_perf_domain *pd;

kernel/power/em_netlink_autogen.c

@@ -11,6 +11,11 @@
 
 #include <uapi/linux/dev_energymodel.h>
 
+/* DEV_ENERGYMODEL_CMD_GET_PERF_DOMAINS - do */
+static const struct nla_policy dev_energymodel_get_perf_domains_nl_policy[DEV_ENERGYMODEL_A_PERF_DOMAIN_PERF_DOMAIN_ID + 1] = {
+	[DEV_ENERGYMODEL_A_PERF_DOMAIN_PERF_DOMAIN_ID] = { .type = NLA_U32, },
+};
+
 /* DEV_ENERGYMODEL_CMD_GET_PERF_TABLE - do */
 static const struct nla_policy dev_energymodel_get_perf_table_nl_policy[DEV_ENERGYMODEL_A_PERF_TABLE_PERF_DOMAIN_ID + 1] = {
 	[DEV_ENERGYMODEL_A_PERF_TABLE_PERF_DOMAIN_ID] = { .type = NLA_U32, },
@@ -18,10 +23,17 @@ static const struct nla_policy dev_energymodel_get_perf_table_nl_policy[DEV_ENER
 
 /* Ops table for dev_energymodel */
 static const struct genl_split_ops dev_energymodel_nl_ops[] = {
+	{
+		.cmd		= DEV_ENERGYMODEL_CMD_GET_PERF_DOMAINS,
+		.doit		= dev_energymodel_nl_get_perf_domains_doit,
+		.policy		= dev_energymodel_get_perf_domains_nl_policy,
+		.maxattr	= DEV_ENERGYMODEL_A_PERF_DOMAIN_PERF_DOMAIN_ID,
+		.flags		= GENL_CMD_CAP_DO,
+	},
 	{
 		.cmd	= DEV_ENERGYMODEL_CMD_GET_PERF_DOMAINS,
-		.doit	= dev_energymodel_nl_get_perf_domains_doit,
-		.flags	= GENL_CMD_CAP_DO,
+		.dumpit	= dev_energymodel_nl_get_perf_domains_dumpit,
+		.flags	= GENL_CMD_CAP_DUMP,
 	},
 	{
 		.cmd		= DEV_ENERGYMODEL_CMD_GET_PERF_TABLE,

kernel/power/em_netlink_autogen.h

@@ -14,6 +14,8 @@
 
 int dev_energymodel_nl_get_perf_domains_doit(struct sk_buff *skb,
 					     struct genl_info *info);
+int dev_energymodel_nl_get_perf_domains_dumpit(struct sk_buff *skb,
+					       struct netlink_callback *cb);
 int dev_energymodel_nl_get_perf_table_doit(struct sk_buff *skb,
 					   struct genl_info *info);