RHCT is a new table defined for RISC-V to communicate the
features of the CPU to the OS. Create a new architecture folder
in drivers/acpi and add RHCT parsing code.
Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>
---
arch/riscv/include/asm/acpi.h | 8 ++++
drivers/acpi/Makefile | 2 +
drivers/acpi/riscv/Makefile | 2 +
drivers/acpi/riscv/rhct.c | 83 +++++++++++++++++++++++++++++++++++
4 files changed, 95 insertions(+)
create mode 100644 drivers/acpi/riscv/Makefile
create mode 100644 drivers/acpi/riscv/rhct.c
@@ -62,6 +62,8 @@ static inline void arch_fix_phys_package_id(int num, u32 slot) { }
void acpi_init_rintc_map(void);
struct acpi_madt_rintc *acpi_cpu_get_madt_rintc(int cpu);
u32 get_acpi_id_for_cpu(int cpu);
+int acpi_get_riscv_isa(struct acpi_table_header *table,
+ unsigned int cpu, const char **isa);
#else
static inline void acpi_init_rintc_map(void) { }
static inline struct acpi_madt_rintc *acpi_cpu_get_madt_rintc(int cpu)
@@ -69,6 +71,12 @@ static inline struct acpi_madt_rintc *acpi_cpu_get_madt_rintc(int cpu)
return NULL;
}
+static inline int acpi_get_riscv_isa(struct acpi_table_header *table,
+ unsigned int cpu, const char **isa)
+{
+ return -EINVAL;
+}
+
#endif /* CONFIG_ACPI */
#endif /*_ASM_ACPI_H*/
@@ -131,3 +131,5 @@ obj-y += dptf/
obj-$(CONFIG_ARM64) += arm64/
obj-$(CONFIG_ACPI_VIOT) += viot.o
+
+obj-$(CONFIG_RISCV) += riscv/
new file mode 100644
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-y += rhct.o
new file mode 100644
@@ -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;
+}