1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2022-2023, Ventana Micro Systems Inc
4 * Author: Sunil V L <sunilvl@ventanamicro.com>
5 *
6 */
7
8 #define pr_fmt(fmt) "ACPI: RHCT: " fmt
9
10 #include <linux/acpi.h>
11
acpi_get_rhct(void)12 static struct acpi_table_header *acpi_get_rhct(void)
13 {
14 static struct acpi_table_header *rhct;
15 acpi_status status;
16
17 /*
18 * RHCT will be used at runtime on every CPU, so we
19 * don't need to call acpi_put_table() to release the table mapping.
20 */
21 if (!rhct) {
22 status = acpi_get_table(ACPI_SIG_RHCT, 0, &rhct);
23 if (ACPI_FAILURE(status)) {
24 pr_warn_once("No RHCT table found\n");
25 return NULL;
26 }
27 }
28
29 return rhct;
30 }
31
32 /*
33 * During early boot, the caller should call acpi_get_table() and pass its pointer to
34 * these functions(and free up later). At run time, since this table can be used
35 * multiple times, NULL may be passed in order to use the cached table.
36 */
acpi_get_riscv_isa(struct acpi_table_header * table,unsigned int cpu,const char ** isa)37 int acpi_get_riscv_isa(struct acpi_table_header *table, unsigned int cpu, const char **isa)
38 {
39 struct acpi_rhct_node_header *node, *ref_node, *end;
40 u32 size_hdr = sizeof(struct acpi_rhct_node_header);
41 u32 size_hartinfo = sizeof(struct acpi_rhct_hart_info);
42 struct acpi_rhct_hart_info *hart_info;
43 struct acpi_rhct_isa_string *isa_node;
44 struct acpi_table_rhct *rhct;
45 u32 *hart_info_node_offset;
46 u32 acpi_cpu_id = get_acpi_id_for_cpu(cpu);
47
48 BUG_ON(acpi_disabled);
49
50 if (!table) {
51 rhct = (struct acpi_table_rhct *)acpi_get_rhct();
52 if (!rhct)
53 return -ENOENT;
54 } else {
55 rhct = (struct acpi_table_rhct *)table;
56 }
57
58 end = ACPI_ADD_PTR(struct acpi_rhct_node_header, rhct, rhct->header.length);
59
60 for (node = ACPI_ADD_PTR(struct acpi_rhct_node_header, rhct, rhct->node_offset);
61 node < end;
62 node = ACPI_ADD_PTR(struct acpi_rhct_node_header, node, node->length)) {
63 if (node->type == ACPI_RHCT_NODE_TYPE_HART_INFO) {
64 hart_info = ACPI_ADD_PTR(struct acpi_rhct_hart_info, node, size_hdr);
65 hart_info_node_offset = ACPI_ADD_PTR(u32, hart_info, size_hartinfo);
66 if (acpi_cpu_id != hart_info->uid)
67 continue;
68
69 for (int i = 0; i < hart_info->num_offsets; i++) {
70 ref_node = ACPI_ADD_PTR(struct acpi_rhct_node_header,
71 rhct, hart_info_node_offset[i]);
72 if (ref_node->type == ACPI_RHCT_NODE_TYPE_ISA_STRING) {
73 isa_node = ACPI_ADD_PTR(struct acpi_rhct_isa_string,
74 ref_node, size_hdr);
75 *isa = isa_node->isa;
76 return 0;
77 }
78 }
79 }
80 }
81
82 return -1;
83 }
84