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-rw-r--r--drivers/acpi/riscv/Makefile2
-rw-r--r--drivers/acpi/riscv/rhct.c83
2 files changed, 85 insertions, 0 deletions
diff --git a/drivers/acpi/riscv/Makefile b/drivers/acpi/riscv/Makefile
new file mode 100644
index 0000000000..8b3b126e0b
--- /dev/null
+++ b/drivers/acpi/riscv/Makefile
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-y += rhct.o
diff --git a/drivers/acpi/riscv/rhct.c b/drivers/acpi/riscv/rhct.c
new file mode 100644
index 0000000000..b280b3e9c7
--- /dev/null
+++ b/drivers/acpi/riscv/rhct.c
@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2022-2023, Ventana Micro Systems Inc
+ * Author: Sunil V L <sunilvl@ventanamicro.com>
+ *
+ */
+
+#define pr_fmt(fmt) "ACPI: RHCT: " fmt
+
+#include <linux/acpi.h>
+
+static struct acpi_table_header *acpi_get_rhct(void)
+{
+ static struct acpi_table_header *rhct;
+ acpi_status status;
+
+ /*
+ * RHCT will be used at runtime on every CPU, so we
+ * don't need to call acpi_put_table() to release the table mapping.
+ */
+ if (!rhct) {
+ status = acpi_get_table(ACPI_SIG_RHCT, 0, &rhct);
+ if (ACPI_FAILURE(status)) {
+ pr_warn_once("No RHCT table found\n");
+ return NULL;
+ }
+ }
+
+ return rhct;
+}
+
+/*
+ * During early boot, the caller should call acpi_get_table() and pass its pointer to
+ * these functions(and free up later). At run time, since this table can be used
+ * multiple times, NULL may be passed in order to use the cached table.
+ */
+int acpi_get_riscv_isa(struct acpi_table_header *table, unsigned int cpu, const char **isa)
+{
+ struct acpi_rhct_node_header *node, *ref_node, *end;
+ u32 size_hdr = sizeof(struct acpi_rhct_node_header);
+ u32 size_hartinfo = sizeof(struct acpi_rhct_hart_info);
+ struct acpi_rhct_hart_info *hart_info;
+ struct acpi_rhct_isa_string *isa_node;
+ struct acpi_table_rhct *rhct;
+ u32 *hart_info_node_offset;
+ u32 acpi_cpu_id = get_acpi_id_for_cpu(cpu);
+
+ BUG_ON(acpi_disabled);
+
+ if (!table) {
+ rhct = (struct acpi_table_rhct *)acpi_get_rhct();
+ if (!rhct)
+ return -ENOENT;
+ } else {
+ rhct = (struct acpi_table_rhct *)table;
+ }
+
+ end = ACPI_ADD_PTR(struct acpi_rhct_node_header, rhct, rhct->header.length);
+
+ for (node = ACPI_ADD_PTR(struct acpi_rhct_node_header, rhct, rhct->node_offset);
+ node < end;
+ node = ACPI_ADD_PTR(struct acpi_rhct_node_header, node, node->length)) {
+ if (node->type == ACPI_RHCT_NODE_TYPE_HART_INFO) {
+ hart_info = ACPI_ADD_PTR(struct acpi_rhct_hart_info, node, size_hdr);
+ hart_info_node_offset = ACPI_ADD_PTR(u32, hart_info, size_hartinfo);
+ if (acpi_cpu_id != hart_info->uid)
+ continue;
+
+ for (int i = 0; i < hart_info->num_offsets; i++) {
+ ref_node = ACPI_ADD_PTR(struct acpi_rhct_node_header,
+ rhct, hart_info_node_offset[i]);
+ if (ref_node->type == ACPI_RHCT_NODE_TYPE_ISA_STRING) {
+ isa_node = ACPI_ADD_PTR(struct acpi_rhct_isa_string,
+ ref_node, size_hdr);
+ *isa = isa_node->isa;
+ return 0;
+ }
+ }
+ }
+ }
+
+ return -1;
+}