drivers/acpi/riscv/rhct.c

   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
  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  */
  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 }