Implement a skeleton framework for debugfs support in the
AMD IOMMU.

Signed-off-by: Gary R Hook <gary.h...@amd.com>
---
 drivers/iommu/Kconfig             |    6 ++---
 drivers/iommu/Makefile            |    2 +-
 drivers/iommu/amd_iommu_debugfs.c |   47 +++++++++++++++++++++++++++++++++++++
 drivers/iommu/amd_iommu_init.c    |    9 ++++---
 drivers/iommu/amd_iommu_proto.h   |    6 +++++
 drivers/iommu/amd_iommu_types.h   |    3 ++
 include/linux/iommu.h             |    8 +++---
 7 files changed, 69 insertions(+), 12 deletions(-)
 create mode 100644 drivers/iommu/amd_iommu_debugfs.c

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index d40248446214..8d50151d5bf4 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -65,9 +65,9 @@ config IOMMU_DEBUG
        depends on DEBUG_FS
        default n
        help
-         Base enablement for access to any IOMMU device. Allows individual
-         drivers to populate debugfs for access to IOMMU registers and
-         data structures.
+         Enable exposure of IOMMU device internals. Allow devices to
+         populate debugfs for access to IOMMU registers and data
+         structures.
 
 config IOMMU_IOVA
        tristate
diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index 5e5c3339681d..0ca250f626d9 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -11,7 +11,7 @@ obj-$(CONFIG_IOMMU_IOVA) += iova.o
 obj-$(CONFIG_OF_IOMMU) += of_iommu.o
 obj-$(CONFIG_MSM_IOMMU) += msm_iommu.o
 obj-$(CONFIG_AMD_IOMMU) += amd_iommu.o amd_iommu_init.o
-obj-$(CONFIG_AMD_IOMMU_DEBUG) += amd_iommu_debugfs.o
+obj-$(CONFIG_IOMMU_DEBUG) += amd_iommu_debugfs.o
 obj-$(CONFIG_AMD_IOMMU_V2) += amd_iommu_v2.o
 obj-$(CONFIG_ARM_SMMU) += arm-smmu.o
 obj-$(CONFIG_ARM_SMMU_V3) += arm-smmu-v3.o
diff --git a/drivers/iommu/amd_iommu_debugfs.c 
b/drivers/iommu/amd_iommu_debugfs.c
new file mode 100644
index 000000000000..3547ad3339c1
--- /dev/null
+++ b/drivers/iommu/amd_iommu_debugfs.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * AMD IOMMU driver
+ *
+ * Copyright (C) 2018 Advanced Micro Devices, Inc.
+ *
+ * Author: Gary R Hook <gary.h...@amd.com>
+ */
+
+#ifdef CONFIG_IOMMU_DEBUG
+
+#include <linux/debugfs.h>
+#include <linux/iommu.h>
+#include <linux/pci.h>
+#include "amd_iommu_proto.h"
+#include "amd_iommu_types.h"
+
+static struct dentry *iommu_debugfs_dir;
+static DEFINE_RWLOCK(iommu_debugfs_lock);
+
+#define        MAX_NAME_LEN    20
+
+void amd_iommu_debugfs_setup(struct amd_iommu *iommu)
+{
+       char name[MAX_NAME_LEN + 1];
+       struct dentry *d_top;
+       unsigned long flags;
+
+       if (!debugfs_initialized())
+               return;
+
+       write_lock_irqsave(&iommu_debugfs_lock, flags);
+       if (!iommu_debugfs_dir && (d_top = iommu_debugfs_setup()))
+               iommu_debugfs_dir = debugfs_create_dir("amd", d_top);
+       write_unlock_irqrestore(&iommu_debugfs_lock, flags);
+       if (iommu_debugfs_dir) {
+               snprintf(name, MAX_NAME_LEN, "iommu%02d", iommu->index);
+               iommu->debugfs_instance = debugfs_create_dir(name,
+                                                            iommu_debugfs_dir);
+               if (!iommu->debugfs_instance)
+                       debugfs_remove_recursive(iommu_debugfs_dir);
+       }
+
+       return;
+}
+
+#endif
diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index 99d48c42a12f..43856c7f4ea1 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -89,6 +89,7 @@
 #define ACPI_DEVFLAG_ATSDIS             0x10000000
 
 #define LOOP_TIMEOUT   100000
+
 /*
  * ACPI table definitions
  *
@@ -2720,6 +2721,7 @@ int __init amd_iommu_enable_faulting(void)
  */
 static int __init amd_iommu_init(void)
 {
+       struct amd_iommu *iommu;
        int ret;
 
        ret = iommu_go_to_state(IOMMU_INITIALIZED);
@@ -2729,14 +2731,15 @@ static int __init amd_iommu_init(void)
                        disable_iommus();
                        free_iommu_resources();
                } else {
-                       struct amd_iommu *iommu;
-
                        uninit_device_table_dma();
                        for_each_iommu(iommu)
                                iommu_flush_all_caches(iommu);
                }
        }
 
+       for_each_iommu(iommu)
+               amd_iommu_debugfs_setup(iommu);
+
        return ret;
 }
 
@@ -2783,8 +2786,6 @@ int __init amd_iommu_detect(void)
        iommu_detected = 1;
        x86_init.iommu.iommu_init = amd_iommu_init;
 
-dump_stack();
-
        return 1;
 }
 
diff --git a/drivers/iommu/amd_iommu_proto.h b/drivers/iommu/amd_iommu_proto.h
index 640c286a0ab9..e19cebc5c740 100644
--- a/drivers/iommu/amd_iommu_proto.h
+++ b/drivers/iommu/amd_iommu_proto.h
@@ -33,6 +33,12 @@ extern void amd_iommu_uninit_devices(void);
 extern void amd_iommu_init_notifier(void);
 extern int amd_iommu_init_api(void);
 
+#ifdef CONFIG_IOMMU_DEBUG
+extern void amd_iommu_debugfs_setup(struct amd_iommu *iommu);
+#else
+static inline void amd_iommu_debugfs_setup(struct amd_iommu *iommu) {}
+#endif
+
 /* Needed for interrupt remapping */
 extern int amd_iommu_prepare(void);
 extern int amd_iommu_enable(void);
diff --git a/drivers/iommu/amd_iommu_types.h b/drivers/iommu/amd_iommu_types.h
index f6b24c7d8b70..6dca9fe38518 100644
--- a/drivers/iommu/amd_iommu_types.h
+++ b/drivers/iommu/amd_iommu_types.h
@@ -591,6 +591,9 @@ struct amd_iommu {
 
        u32 flags;
        volatile u64 __aligned(8) cmd_sem;
+
+       /* DebugFS Info */
+       struct dentry *debugfs_instance;
 };
 
 static inline struct amd_iommu *dev_to_amd_iommu(struct device *dev)
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 98527f9b473b..dbfff811aa25 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -412,6 +412,10 @@ void iommu_fwspec_free(struct device *dev);
 int iommu_fwspec_add_ids(struct device *dev, u32 *ids, int num_ids);
 const struct iommu_ops *iommu_ops_from_fwnode(struct fwnode_handle *fwnode);
 
+#ifdef CONFIG_IOMMU_DEBUG
+extern struct dentry *iommu_debugfs_setup(void);
+#endif
+
 #else /* CONFIG_IOMMU_API */
 
 struct iommu_ops {};
@@ -696,10 +700,6 @@ const struct iommu_ops *iommu_ops_from_fwnode(struct 
fwnode_handle *fwnode)
        return NULL;
 }
 
-#ifdef CONFIG_IOMMU_DEBUG
-extern struct dentry *iommu_debugfs_setup(void);
-#endif
-
 #endif /* CONFIG_IOMMU_API */
 
 #endif /* __LINUX_IOMMU_H */

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