Add support for representing each memory-controller instance (one
per NUMA node / socket) as its own interconnect (ICC) provider,
with its own MC client nodes, to match the hardware topology on
multi-socket Tegra SoCs.

Use the NUMA node ID to make client IDs globally unique across
per-socket providers, since the ICC framework allocates node IDs
from a single global IDR. Per-socket MC and EMC node names are
also derived from dev_name() so they match the corresponding
debugfs subdirectory. On single-socket platforms (NUMA_NO_NODE)
the existing client IDs and node-name strings are preserved.

Each socket's MC and EMC therefore get their own debugfs
subdirectory under /sys/kernel/debug/{mc,emc}/. The parent
directories are created on first probe.

Bandwidth requests from MC clients in a socket are routed to
that socket's local BPMP.

Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
---
v1 -> v2:
- Mutex protected lazy creation of the mc/emc debugfs parent.
- Rename {mc|emc}_debugfs_root to tegra_{mc|emc}_debugfs_root.

[1] https://lore.kernel.org/lkml/20260521140546.3023819-1-sumitg@nvidia.com/
---
 drivers/memory/tegra/mc.c           | 40 ++++++++++++++++-----
 drivers/memory/tegra/mc.h           | 31 ++++++++++++++++
 drivers/memory/tegra/tegra186-emc.c | 55 ++++++++++++++++++++++++-----
 3 files changed, 109 insertions(+), 17 deletions(-)

diff --git a/drivers/memory/tegra/mc.c b/drivers/memory/tegra/mc.c
index ec80ea9cc173..51ad0d3e48d4 100644
--- a/drivers/memory/tegra/mc.c
+++ b/drivers/memory/tegra/mc.c
@@ -3,6 +3,7 @@
  * Copyright (C) 2014-2026 NVIDIA CORPORATION.  All rights reserved.
  */
 
+#include <linux/cleanup.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/dma-mapping.h>
@@ -10,6 +11,7 @@
 #include <linux/interrupt.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
 #include <linux/of.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
@@ -22,6 +24,9 @@
 
 #include "mc.h"
 
+static DEFINE_MUTEX(tegra_mc_debugfs_root_lock);
+static struct dentry *tegra_mc_debugfs_root;
+
 static const struct of_device_id tegra_mc_of_match[] = {
 #ifdef CONFIG_ARCH_TEGRA_2x_SOC
 	{ .compatible = "nvidia,tegra20-mc-gart", .data = &tegra20_mc_soc },
@@ -778,7 +783,7 @@ struct icc_node *tegra_mc_icc_xlate(const struct of_phandle_args *spec, void *da
 	struct icc_node *node;
 
 	list_for_each_entry(node, &mc->provider.nodes, node_list) {
-		if (node->id == spec->args[0])
+		if (tegra_mc_client_id_from_node(node) == spec->args[0])
 			return node;
 	}
 
@@ -834,6 +839,7 @@ const struct tegra_mc_icc_ops tegra_mc_icc_ops = {
  */
 static int tegra_mc_interconnect_setup(struct tegra_mc *mc)
 {
+	int node_id = dev_to_node(mc->dev);
 	struct icc_node *node;
 	unsigned int i;
 	int err;
@@ -854,31 +860,40 @@ static int tegra_mc_interconnect_setup(struct tegra_mc *mc)
 	icc_provider_init(&mc->provider);
 
 	/* create Memory Controller node */
-	node = icc_node_create(TEGRA_ICC_MC);
+	node = tegra_mc_icc_node_create(node_id, TEGRA_ICC_MC);
 	if (IS_ERR(node))
 		return PTR_ERR(node);
 
-	node->name = "Memory Controller";
+	if (node_id == NUMA_NO_NODE)
+		node->name = "Memory Controller";
+	else
+		node->name = dev_name(mc->dev);
+
 	icc_node_add(node, &mc->provider);
 
 	/* link Memory Controller to External Memory Controller */
-	err = icc_link_create(node, TEGRA_ICC_EMC);
+	err = tegra_mc_icc_link_create(node, node_id, TEGRA_ICC_EMC);
 	if (err)
 		goto remove_nodes;
 
 	for (i = 0; i < mc->soc->num_clients; i++) {
 		/* create MC client node */
-		node = icc_node_create(mc->soc->clients[i].id);
+		node = tegra_mc_icc_node_create(node_id, mc->soc->clients[i].id);
 		if (IS_ERR(node)) {
 			err = PTR_ERR(node);
 			goto remove_nodes;
 		}
 
-		node->name = mc->soc->clients[i].name;
+		if (node_id == NUMA_NO_NODE)
+			node->name = mc->soc->clients[i].name;
+		else
+			node->name = devm_kasprintf(mc->dev, GFP_KERNEL, "%d-%s",
+						    node_id, mc->soc->clients[i].name);
+
 		icc_node_add(node, &mc->provider);
 
 		/* link Memory Client to Memory Controller */
-		err = icc_link_create(node, TEGRA_ICC_MC);
+		err = tegra_mc_icc_link_create(node, node_id, TEGRA_ICC_MC);
 		if (err)
 			goto remove_nodes;
 
@@ -957,7 +972,16 @@ static int tegra_mc_probe(struct platform_device *pdev)
 	if (IS_ERR(mc->regs))
 		return PTR_ERR(mc->regs);
 
-	mc->debugfs.root = debugfs_create_dir("mc", NULL);
+	scoped_guard(mutex, &tegra_mc_debugfs_root_lock) {
+		if (!tegra_mc_debugfs_root)
+			tegra_mc_debugfs_root = debugfs_create_dir("mc", NULL);
+
+		if (dev_to_node(mc->dev) == NUMA_NO_NODE)
+			mc->debugfs.root = tegra_mc_debugfs_root;
+		else
+			mc->debugfs.root = debugfs_create_dir(dev_name(mc->dev),
+							      tegra_mc_debugfs_root);
+	}
 
 	if (mc->soc->ops && mc->soc->ops->probe) {
 		err = mc->soc->ops->probe(mc);
diff --git a/drivers/memory/tegra/mc.h b/drivers/memory/tegra/mc.h
index e94d265d7b67..be6ec0f63f59 100644
--- a/drivers/memory/tegra/mc.h
+++ b/drivers/memory/tegra/mc.h
@@ -8,6 +8,7 @@
 
 #include <linux/bits.h>
 #include <linux/io.h>
+#include <linux/numa.h>
 #include <linux/types.h>
 
 #include <soc/tegra/mc.h>
@@ -167,6 +168,36 @@ icc_provider_to_tegra_mc(struct icc_provider *provider)
 	return container_of(provider, struct tegra_mc, provider);
 }
 
+/*
+ * Compose a globally-unique ICC node ID. On single-socket
+ * systems (NUMA_NO_NODE), the SoC client ID is returned unchanged.
+ * On multi-socket systems, the NUMA node ID is encoded in the
+ * upper bits of the returned ID.
+ */
+static inline u32 tegra_mc_get_client_id(int node_id, int id)
+{
+	if (node_id == NUMA_NO_NODE)
+		return id;
+
+	return ((node_id + 1) << 16) | id;
+}
+
+static inline struct icc_node *tegra_mc_icc_node_create(int node_id, int id)
+{
+	return icc_node_create(tegra_mc_get_client_id(node_id, id));
+}
+
+static inline int tegra_mc_icc_link_create(struct icc_node *node, int node_id, int id)
+{
+	return icc_link_create(node, tegra_mc_get_client_id(node_id, id));
+}
+
+/* Return the SoC client ID encoded in an ICC node ID. */
+static inline u32 tegra_mc_client_id_from_node(const struct icc_node *node)
+{
+	return node->id & GENMASK(15, 0);
+}
+
 static inline u32 mc_ch_readl(const struct tegra_mc *mc, int ch,
 			      unsigned long offset)
 {
diff --git a/drivers/memory/tegra/tegra186-emc.c b/drivers/memory/tegra/tegra186-emc.c
index 03ebab6fbe68..e6a2e19693c0 100644
--- a/drivers/memory/tegra/tegra186-emc.c
+++ b/drivers/memory/tegra/tegra186-emc.c
@@ -3,16 +3,22 @@
  * Copyright (C) 2019-2025 NVIDIA CORPORATION.  All rights reserved.
  */
 
+#include <linux/cleanup.h>
 #include <linux/clk.h>
 #include <linux/debugfs.h>
+#include <linux/fs.h>
 #include <linux/module.h>
 #include <linux/mod_devicetable.h>
+#include <linux/mutex.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
 
 #include <soc/tegra/bpmp.h>
 #include "mc.h"
 
+static DEFINE_MUTEX(tegra_emc_debugfs_root_lock);
+static struct dentry *tegra_emc_debugfs_root;
+
 struct tegra186_emc_dvfs {
 	unsigned long latency;
 	unsigned long rate;
@@ -207,7 +213,17 @@ static int tegra186_emc_get_emc_dvfs_latency(struct tegra186_emc *emc)
 		return err;
 	}
 
-	emc->debugfs.root = debugfs_create_dir("emc", NULL);
+	scoped_guard(mutex, &tegra_emc_debugfs_root_lock) {
+		if (!tegra_emc_debugfs_root)
+			tegra_emc_debugfs_root = debugfs_create_dir("emc", NULL);
+
+		if (dev_to_node(emc->dev) == NUMA_NO_NODE)
+			emc->debugfs.root = tegra_emc_debugfs_root;
+		else
+			emc->debugfs.root = debugfs_create_dir(dev_name(emc->dev),
+							       tegra_emc_debugfs_root);
+	}
+
 	debugfs_create_file("available_rates", 0444, emc->debugfs.root, emc,
 			    &tegra186_emc_debug_available_rates_fops);
 	debugfs_create_file("min_rate", 0644, emc->debugfs.root, emc,
@@ -239,7 +255,7 @@ tegra186_emc_of_icc_xlate(const struct of_phandle_args *spec, void *data)
 
 	/* External Memory is the only possible ICC route */
 	list_for_each_entry(node, &provider->nodes, node_list) {
-		if (node->id != TEGRA_ICC_EMEM)
+		if (tegra_mc_client_id_from_node(node) != TEGRA_ICC_EMEM)
 			continue;
 
 		return node;
@@ -260,6 +276,7 @@ static int tegra186_emc_interconnect_init(struct tegra186_emc *emc)
 {
 	struct tegra_mc *mc = dev_get_drvdata(emc->dev->parent);
 	const struct tegra_mc_soc *soc = mc->soc;
+	int node_id = dev_to_node(mc->dev);
 	struct icc_node *node;
 	int err;
 
@@ -273,26 +290,36 @@ static int tegra186_emc_interconnect_init(struct tegra186_emc *emc)
 	icc_provider_init(&emc->provider);
 
 	/* create External Memory Controller node */
-	node = icc_node_create(TEGRA_ICC_EMC);
-	if (IS_ERR(node))
-		return PTR_ERR(node);
+	node = tegra_mc_icc_node_create(node_id, TEGRA_ICC_EMC);
+	if (IS_ERR(node)) {
+		err = PTR_ERR(node);
+		goto remove_nodes;
+	}
+
+	if (node_id == NUMA_NO_NODE)
+		node->name = "External Memory Controller";
+	else
+		node->name = dev_name(emc->dev);
 
-	node->name = "External Memory Controller";
 	icc_node_add(node, &emc->provider);
 
 	/* link External Memory Controller to External Memory (DRAM) */
-	err = icc_link_create(node, TEGRA_ICC_EMEM);
+	err = tegra_mc_icc_link_create(node, node_id, TEGRA_ICC_EMEM);
 	if (err)
 		goto remove_nodes;
 
 	/* create External Memory node */
-	node = icc_node_create(TEGRA_ICC_EMEM);
+	node = tegra_mc_icc_node_create(node_id, TEGRA_ICC_EMEM);
 	if (IS_ERR(node)) {
 		err = PTR_ERR(node);
 		goto remove_nodes;
 	}
 
-	node->name = "External Memory (DRAM)";
+	if (node_id == NUMA_NO_NODE)
+		node->name = "External Memory (DRAM)";
+	else
+		node->name = devm_kasprintf(emc->dev, GFP_KERNEL, "%d-dram", node_id);
+
 	icc_node_add(node, &emc->provider);
 
 	err = icc_provider_register(&emc->provider);
@@ -385,6 +412,16 @@ static void tegra186_emc_remove(struct platform_device *pdev)
 
 	debugfs_remove_recursive(emc->debugfs.root);
 
+	scoped_guard(mutex, &tegra_emc_debugfs_root_lock) {
+		if (emc->debugfs.root == tegra_emc_debugfs_root) {
+			tegra_emc_debugfs_root = NULL;
+		} else if (tegra_emc_debugfs_root &&
+			   simple_empty(tegra_emc_debugfs_root)) {
+			debugfs_remove(tegra_emc_debugfs_root);
+			tegra_emc_debugfs_root = NULL;
+		}
+	}
+
 	mc->bpmp = NULL;
 	tegra_bpmp_put(emc->bpmp);
 }
-- 
2.34.1