[PW_SID:1071025] iommu/riscv: Add DebugFS support for register dump

drivers/iommu/riscv/Kconfig

@@ -18,3 +18,14 @@ config RISCV_IOMMU_PCI
 	def_bool y if RISCV_IOMMU && PCI_MSI
 	help
 	  Support for the PCIe implementation of RISC-V IOMMU architecture.
+
+config RISCV_IOMMU_DEBUGFS
+    bool "RISC-V IOMMU Debugfs Support"
+    depends on RISCV_IOMMU
+    depends on IOMMU_DEBUGFS
+    help
+      Expose RISC-V IOMMU internals via debugfs. This includes
+      register dumps, queue status, and other hardware-specific
+      information useful for debugging.
+
+      If unsure, say N.

drivers/iommu/riscv/Makefile

@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0-only
 obj-y += iommu.o iommu-platform.o
 obj-$(CONFIG_RISCV_IOMMU_PCI) += iommu-pci.o
+obj-$(CONFIG_RISCV_IOMMU_DEBUGFS) += debugfs.o

drivers/iommu/riscv/debugfs.c

@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/debugfs.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+
+#include "iommu.h"
+
+static const struct debugfs_reg32 riscv_iommu_regs[] = {
+	/* --- Global Configuration --- */
+	{ .name = "capabilities",       .offset = RISCV_IOMMU_REG_CAPABILITIES  },
+	{ .name = "fctl",               .offset = RISCV_IOMMU_REG_FCTL          },
+	{ .name = "ddtp",               .offset = RISCV_IOMMU_REG_DDTP          },
+	/* --- Command Queue --- */
+	{ .name = "cqb",                .offset = RISCV_IOMMU_REG_CQB           },
+	{ .name = "cqh",                .offset = RISCV_IOMMU_REG_CQH           },
+	{ .name = "cqt",                .offset = RISCV_IOMMU_REG_CQT           },
+	{ .name = "cqcsr",              .offset = RISCV_IOMMU_REG_CQCSR         },
+	/* --- Fault Queue --- */
+	{ .name = "fqb",                .offset = RISCV_IOMMU_REG_FQB           },
+	{ .name = "fqh",                .offset = RISCV_IOMMU_REG_FQH           },
+	{ .name = "fqt",                .offset = RISCV_IOMMU_REG_FQT           },
+	{ .name = "fqcsr",              .offset = RISCV_IOMMU_REG_FQCSR         },
+	/* --- Interrupts --- */
+	{ .name = "ipsr",               .offset = RISCV_IOMMU_REG_IPSR          },
+	{ .name = "icvec",              .offset = RISCV_IOMMU_REG_ICVEC         },
+};
+
+void riscv_iommu_debugfs_init(struct riscv_iommu_device *iommu)
+{
+	struct debugfs_regset32 *regset;
+
+	if (!iommu_debugfs_dir)
+		return;
+
+	iommu->debugfs_dir = debugfs_create_dir(dev_name(iommu->dev), iommu_debugfs_dir);
+	if (IS_ERR_OR_NULL(iommu->debugfs_dir))
+		return;
+
+	regset = devm_kzalloc(iommu->dev, sizeof(*regset), GFP_KERNEL);
+	if (!regset)
+		return;
+
+	regset->regs = riscv_iommu_regs;
+	regset->nregs = ARRAY_SIZE(riscv_iommu_regs);
+	regset->base = iommu->reg;
+
+	debugfs_create_regset32("registers", 0444, iommu->debugfs_dir, regset);
+}
+
+void riscv_iommu_debugfs_remove(struct riscv_iommu_device *iommu)
+{
+	debugfs_remove_recursive(iommu->debugfs_dir);
+}

drivers/iommu/riscv/iommu.c

@@ -1609,6 +1609,7 @@ void riscv_iommu_remove(struct riscv_iommu_device *iommu)
 	riscv_iommu_iodir_set_mode(iommu, RISCV_IOMMU_DDTP_IOMMU_MODE_OFF);
 	riscv_iommu_queue_disable(&iommu->cmdq);
 	riscv_iommu_queue_disable(&iommu->fltq);
+	riscv_iommu_debugfs_remove(iommu);
 }
 
 int riscv_iommu_init(struct riscv_iommu_device *iommu)
@@ -1669,6 +1670,8 @@ int riscv_iommu_init(struct riscv_iommu_device *iommu)
 		goto err_remove_sysfs;
 	}
 
+	riscv_iommu_debugfs_init(iommu);
+
 	return 0;
 
 err_remove_sysfs:

drivers/iommu/riscv/iommu.h

@@ -60,6 +60,10 @@ struct riscv_iommu_device {
 	unsigned int ddt_mode;
 	dma_addr_t ddt_phys;
 	u64 *ddt_root;
+
+#ifdef CONFIG_RISCV_IOMMU_DEBUGFS
+	struct dentry *debugfs_dir;
+#endif
 };
 
 int riscv_iommu_init(struct riscv_iommu_device *iommu);
@@ -86,4 +90,12 @@ void riscv_iommu_disable(struct riscv_iommu_device *iommu);
 	readx_poll_timeout(readl_relaxed, (iommu)->reg + (addr), val, cond, \
 			   delay_us, timeout_us)
 
+#ifdef CONFIG_RISCV_IOMMU_DEBUGFS
+void riscv_iommu_debugfs_init(struct riscv_iommu_device *iommu);
+void riscv_iommu_debugfs_remove(struct riscv_iommu_device *iommu);
+#else
+static inline void riscv_iommu_debugfs_init(struct riscv_iommu_device *iommu) { }
+static inline void riscv_iommu_debugfs_remove(struct riscv_iommu_device *iommu) { }
+#endif
+
 #endif