drivers/acpi: RISC-V: Add RHCT related code

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>
Link: https://lore.kernel.org/r/20230515054928.2079268-11-sunilvl@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/include/asm/acpi.h b/arch/riscv/include/asm/acpi.h
index 6519529..3947175 100644 (file)
--- a/arch/riscv/include/asm/acpi.h
+++ b/arch/riscv/include/asm/acpi.h
@@ -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*/

diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index feb36c0..3fc5a0d 100644 (file)
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -131,3 +131,5 @@ obj-y                               += dptf/
 obj-$(CONFIG_ARM64)            += arm64/
 
 obj-$(CONFIG_ACPI_VIOT)                += viot.o
+
+obj-$(CONFIG_RISCV)            += riscv/

diff --git a/drivers/acpi/riscv/Makefile b/drivers/acpi/riscv/Makefile
new file mode 100644 (file)
index 0000000..8b3b126
--- /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 (file)
index 0000000..b280b3e
--- /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;
+}