From: Qinxin Xia <xiaqinxin@huawei•com>
To: <robin.murphy@arm•com>, <nicolinc@nvidia•com>, <will@kernel•org>,
<jpb@kernel•org>
Cc: <linux-arm-kernel@lists•infradead.org>, <iommu@lists•linux.dev>,
<xiaqinxin@huawei•com>, <wangzhou1@hisilicon•com>,
<prime.zeng@hisilicon•com>, <fanghao11@huawei•com>,
<jonathan.cameron@huawei•com>, <wuyifan50@huawei•com>,
<linuxarm@huawei•com>, <linux-kernel@vger•kernel.org>
Subject: [PATCH 1/5] iommu/arm-smmu-v3: Add basic debugfs framework
Date: Wed, 20 May 2026 14:37:07 +0800 [thread overview]
Message-ID: <20260520063714.2440584-1-xiaqinxin@huawei.com> (raw)
In-Reply-To: <20260328101706.3448655-1-xiaqinxin@huawei.com>
Add basic debugfs framework for ARM SMMUv3 driver. This creates the
root directory structure and provides capability display functionality.
The debugfs hierarchy is organized as:
/sys/kernel/debug/iommu/arm_smmu_v3/
└── smmu<ioaddr>/
└── capabilities
Signed-off-by: Qinxin Xia <xiaqinxin@huawei•com>
---
drivers/iommu/Kconfig | 11 ++
drivers/iommu/arm/arm-smmu-v3/Makefile | 1 +
.../arm/arm-smmu-v3/arm-smmu-v3-debugfs.c | 172 ++++++++++++++++++
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 16 +-
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 13 ++
5 files changed, 212 insertions(+), 1 deletion(-)
create mode 100644 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-debugfs.c
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index f86262b11416..f28f09adba03 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -93,6 +93,17 @@ config IOMMU_DEBUGFS
debug/iommu directory, and then populate a subdirectory with
entries as required.
+config ARM_SMMU_V3_DEBUGFS
+ bool "ARM SMMUv3 DebugFS support"
+ depends on ARM_SMMU_V3 && IOMMU_DEBUGFS
+ help
+ Expose ARM SMMUv3 internal state via debugfs for debugging and
+ diagnostics. This creates /sys/kernel/debug/iommu/arm_smmu_v3/
+ with detailed information about SMMU configuration, stream tables,
+ and context descriptors.
+
+ Say N unless you are debugging SMMU issues.
+
choice
prompt "IOMMU default domain type"
depends on IOMMU_API
diff --git a/drivers/iommu/arm/arm-smmu-v3/Makefile b/drivers/iommu/arm/arm-smmu-v3/Makefile
index 493a659cc66b..787538fb7054 100644
--- a/drivers/iommu/arm/arm-smmu-v3/Makefile
+++ b/drivers/iommu/arm/arm-smmu-v3/Makefile
@@ -4,5 +4,6 @@ arm_smmu_v3-y := arm-smmu-v3.o
arm_smmu_v3-$(CONFIG_ARM_SMMU_V3_IOMMUFD) += arm-smmu-v3-iommufd.o
arm_smmu_v3-$(CONFIG_ARM_SMMU_V3_SVA) += arm-smmu-v3-sva.o
arm_smmu_v3-$(CONFIG_TEGRA241_CMDQV) += tegra241-cmdqv.o
+arm_smmu_v3-$(CONFIG_ARM_SMMU_V3_DEBUGFS) += arm-smmu-v3-debugfs.o
obj-$(CONFIG_ARM_SMMU_V3_KUNIT_TEST) += arm-smmu-v3-test.o
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-debugfs.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-debugfs.c
new file mode 100644
index 000000000000..1fc2cd1651b4
--- /dev/null
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-debugfs.c
@@ -0,0 +1,172 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ARM SMMUv3 DebugFS Support
+ *
+ * Directory Structure:
+ * /sys/kernel/debug/iommu/arm_smmu_v3/
+ * └── smmu<ioaddr>/
+ * ├── capabilities # SMMU feature capabilities and configuration
+ *
+ * The capabilities file provides detailed information about:
+ * - translation stage support (Stage1/Stage2)
+ * - System coherency, ATS, and PRI feature availability
+ * - Stream table size and command/event queue depths
+ *
+ * Copyright (C) 2026 HiSilicon Limited.
+ * Author: Qinxin Xia <xiaqinxin@huawei•com>
+ */
+
+#include <linux/cleanup.h>
+#include <linux/debugfs.h>
+#include <linux/slab.h>
+#include "arm-smmu-v3.h"
+
+static struct dentry *smmu_debugfs_root;
+static DEFINE_MUTEX(arm_smmu_debugfs_lock);
+
+/**
+ * smmu_debugfs_capabilities_show() - Display SMMU capabilities
+ * @seq: seq_file to write to
+ * @unused: unused parameter
+ *
+ * Errors are reported via seq_puts, the function always returns 0
+ */
+static int smmu_debugfs_capabilities_show(struct seq_file *seq, void *unused)
+{
+ struct arm_smmu_device *smmu = seq->private;
+
+ if (!smmu) {
+ seq_puts(seq, "SMMU not available\n");
+ return 0;
+ }
+
+ seq_puts(seq, "SMMUv3 Capabilities:\n");
+ seq_printf(seq, " Stage1 Translation: %s\n",
+ smmu->features & ARM_SMMU_FEAT_TRANS_S1 ? "Yes" : "No");
+ seq_printf(seq, " Stage2 Translation: %s\n",
+ smmu->features & ARM_SMMU_FEAT_TRANS_S2 ? "Yes" : "No");
+ seq_printf(seq, " Coherent Walk: %s\n",
+ smmu->features & ARM_SMMU_FEAT_COHERENCY ? "Yes" : "No");
+ seq_printf(seq, " ATS Support: %s\n",
+ smmu->features & ARM_SMMU_FEAT_ATS ? "Yes" : "No");
+ seq_printf(seq, " PRI Support: %s\n",
+ smmu->features & ARM_SMMU_FEAT_PRI ? "Yes" : "No");
+ seq_printf(seq, " Stream Table Size: %llu\n", 1ULL << smmu->sid_bits);
+ seq_printf(seq, " Command Queue Depth: %d\n",
+ 1 << smmu->cmdq.q.llq.max_n_shift);
+ seq_printf(seq, " Event Queue Depth: %d\n",
+ 1 << smmu->evtq.q.llq.max_n_shift);
+
+ return 0;
+}
+
+static int smmu_debugfs_capabilities_open(struct inode *inode, struct file *file)
+{
+ struct arm_smmu_device *smmu = inode->i_private;
+ int ret;
+
+ if (!smmu || !get_device(smmu->dev))
+ return -ENODEV;
+
+ ret = single_open(file, smmu_debugfs_capabilities_show, smmu);
+ if (ret)
+ put_device(smmu->dev);
+
+ return ret;
+}
+
+static int smmu_debugfs_capabilities_release(struct inode *inode, struct file *file)
+{
+ struct seq_file *seq = file->private_data;
+ struct arm_smmu_device *smmu = seq->private;
+
+ single_release(inode, file);
+ if (smmu)
+ put_device(smmu->dev);
+
+ return 0;
+}
+
+static const struct file_operations smmu_debugfs_capabilities_fops = {
+ .owner = THIS_MODULE,
+ .open = smmu_debugfs_capabilities_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = smmu_debugfs_capabilities_release,
+};
+
+/**
+ * arm_smmu_debugfs_setup() - Initialize debugfs for SMMU device
+ * @smmu: SMMU device to setup debugfs for
+ * @name: SMMU device name
+ *
+ * This function creates the basic debugfs directory structure for an SMMU device.
+ *
+ * Return: 0 on success, negative error code on failure
+ */
+int arm_smmu_debugfs_setup(struct arm_smmu_device *smmu, const char *name)
+{
+ struct arm_smmu_debugfs *debugfs;
+ struct dentry *smmu_dir;
+
+ /* Create root directory if it doesn't exist */
+ scoped_guard(mutex, &arm_smmu_debugfs_lock) {
+ if (!smmu_debugfs_root) {
+ /* Once created, it will not be removed */
+ smmu_debugfs_root = debugfs_create_dir("arm_smmu_v3",
+ iommu_debugfs_dir);
+ if (IS_ERR(smmu_debugfs_root)) {
+ smmu_debugfs_root = NULL;
+ return -ENOMEM;
+ }
+ }
+ }
+
+ /* Allocate debugfs structure */
+ debugfs = kzalloc_obj(*debugfs);
+ if (!debugfs)
+ return -ENOMEM;
+
+ /* Create SMMU instance directory */
+ smmu_dir = debugfs_create_dir(name, smmu_debugfs_root);
+ if (IS_ERR(smmu_dir)) {
+ kfree(debugfs);
+ smmu->debugfs = NULL;
+ return PTR_ERR(smmu_dir);
+ }
+
+ debugfs->smmu_dir = smmu_dir;
+ smmu->debugfs = debugfs;
+
+ /* Create capabilities file */
+ debugfs_create_file("capabilities", 0444, smmu_dir, smmu,
+ &smmu_debugfs_capabilities_fops);
+
+ dev_dbg(smmu->dev, "debugfs initialized for %s\n", name);
+ return 0;
+}
+
+/**
+ * arm_smmu_debugfs_remove() - Clean up debugfs entries for an SMMU device
+ * @smmu: SMMU device
+ *
+ * This function removes the debugfs directories created by setup.
+ */
+void arm_smmu_debugfs_remove(struct arm_smmu_device *smmu)
+{
+ struct arm_smmu_debugfs *debugfs;
+ struct dentry *smmu_dir;
+
+ scoped_guard(mutex, &arm_smmu_debugfs_lock) {
+ debugfs = smmu->debugfs;
+ if (!debugfs)
+ return;
+
+ smmu_dir = debugfs->smmu_dir;
+ kfree(debugfs);
+ smmu->debugfs = NULL;
+ }
+
+ /* Remove outside lock to avoid blocking on active VFS operations */
+ debugfs_remove_recursive(smmu_dir);
+}
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index e8d7dbe495f0..929b8ead95b0 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -5469,6 +5469,7 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
resource_size_t ioaddr;
struct arm_smmu_device *smmu;
struct device *dev = &pdev->dev;
+ char name[32];
smmu = devm_kzalloc(dev, sizeof(*smmu), GFP_KERNEL);
if (!smmu)
@@ -5496,6 +5497,7 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
return -EINVAL;
}
ioaddr = res->start;
+ snprintf(name, sizeof(name), "smmu3.%pa", &ioaddr);
/*
* Don't map the IMPLEMENTATION DEFINED regions, since they may contain
@@ -5548,6 +5550,12 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
/* Check for RMRs and install bypass STEs if any */
arm_smmu_rmr_install_bypass_ste(smmu);
+#ifdef CONFIG_ARM_SMMU_V3_DEBUGFS
+ ret = arm_smmu_debugfs_setup(smmu, name);
+ if (ret)
+ dev_warn(dev, "Failed to create debugfs!\n");
+#endif
+
/* Reset the device */
ret = arm_smmu_device_reset(smmu);
if (ret)
@@ -5555,7 +5563,7 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
/* And we're up. Go go go! */
ret = iommu_device_sysfs_add(&smmu->iommu, dev, NULL,
- "smmu3.%pa", &ioaddr);
+ "%s", name);
if (ret)
goto err_disable;
@@ -5570,6 +5578,9 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
err_free_sysfs:
iommu_device_sysfs_remove(&smmu->iommu);
err_disable:
+#ifdef CONFIG_ARM_SMMU_V3_DEBUGFS
+ arm_smmu_debugfs_remove(smmu);
+#endif
arm_smmu_device_disable(smmu);
err_free_iopf:
iopf_queue_free(smmu->evtq.iopf);
@@ -5582,6 +5593,9 @@ static void arm_smmu_device_remove(struct platform_device *pdev)
iommu_device_unregister(&smmu->iommu);
iommu_device_sysfs_remove(&smmu->iommu);
+#ifdef CONFIG_ARM_SMMU_V3_DEBUGFS
+ arm_smmu_debugfs_remove(smmu);
+#endif
arm_smmu_device_disable(smmu);
iopf_queue_free(smmu->evtq.iopf);
ida_destroy(&smmu->vmid_map);
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
index ef42df4753ec..8e1c19b6831c 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -820,6 +820,15 @@ struct arm_smmu_impl_ops {
const struct iommu_user_data *user_data);
};
+#ifdef CONFIG_ARM_SMMU_V3_DEBUGFS
+struct arm_smmu_debugfs {
+ struct dentry *smmu_dir;
+};
+
+int arm_smmu_debugfs_setup(struct arm_smmu_device *smmu, const char *name);
+void arm_smmu_debugfs_remove(struct arm_smmu_device *smmu);
+#endif
+
/* An SMMUv3 instance */
struct arm_smmu_device {
struct device *dev;
@@ -890,6 +899,10 @@ struct arm_smmu_device {
struct rb_root streams;
struct mutex streams_mutex;
+
+#ifdef CONFIG_ARM_SMMU_V3_DEBUGFS
+ struct arm_smmu_debugfs *debugfs;
+#endif
};
struct arm_smmu_stream {
--
2.33.0
next prev parent reply other threads:[~2026-05-20 6:37 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-28 10:17 [RFC PATCH v2 0/5] Add debugfs support for ARM SMMUv3 Qinxin Xia
2026-03-28 10:17 ` [RFC PATCH v2 1/5] iommu/arm-smmu-v3: Add basic debugfs framework Qinxin Xia
2026-03-30 10:46 ` Nicolin Chen
2026-04-02 3:50 ` Qinxin Xia
2026-03-28 10:17 ` [RFC PATCH v2 2/5] iommu/arm-smmu-v3: Add register display to debugfs Qinxin Xia
2026-03-30 11:25 ` Nicolin Chen
2026-03-28 10:17 ` [RFC PATCH v2 3/5] iommu/arm-smmu-v3: Add Stream Table Entry " Qinxin Xia
2026-04-04 5:43 ` Nicolin Chen
2026-03-28 10:17 ` [RFC PATCH v2 4/5] iommu/arm-smmu-v3: Add device symlink in stream table debugfs Qinxin Xia
2026-03-28 10:17 ` [RFC PATCH v2 5/5] iommu/arm-smmu-v3: Add Context Descriptor display to debugfs Qinxin Xia
2026-05-20 6:37 ` [PATCH 0/5] Add debugfs support for ARM SMMUv3 Qinxin Xia
2026-05-20 6:37 ` Qinxin Xia [this message]
2026-05-27 0:41 ` [PATCH 1/5] iommu/arm-smmu-v3: Add basic debugfs framework Nicolin Chen
2026-05-20 6:37 ` [PATCH 2/5] iommu/arm-smmu-v3: Add register display to debugfs Qinxin Xia
2026-05-27 1:28 ` Nicolin Chen
2026-05-20 6:37 ` [PATCH 3/5] iommu/arm-smmu-v3: Add Stream Table Entry " Qinxin Xia
2026-05-27 2:18 ` Nicolin Chen
2026-05-27 2:43 ` Nicolin Chen
2026-05-20 6:37 ` [PATCH 4/5] iommu/arm-smmu-v3: Add device symlink in stream table debugfs Qinxin Xia
2026-05-20 6:37 ` [PATCH 5/5] iommu/arm-smmu-v3: Add Context Descriptor display to debugfs Qinxin Xia
2026-05-27 2:40 ` Nicolin Chen
2026-05-27 0:07 ` [PATCH 0/5] Add debugfs support for ARM SMMUv3 Nicolin Chen
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