drivers/acpi/processor_pdc.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2005 Intel Corporation
   4  * Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
   5  *
   6  *      Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
   7  *      - Added _PDC for platforms with Intel CPUs
   8  */
   9
  10 #define pr_fmt(fmt) "ACPI: " fmt
  11
  12 #include <linux/slab.h>
  13 #include <linux/acpi.h>
  14 #include <acpi/processor.h>
  15
  16 #include "internal.h"
  17
  18 static void acpi_set_pdc_bits(u32 *buf)
  19 {
  20         buf[0] = ACPI_PDC_REVISION_ID;
  21         buf[1] = 1;
  22         buf[2] = 0;
  23
  24         /* Twiddle arch-specific bits needed for _PDC */
  25         arch_acpi_set_proc_cap_bits(&buf[2]);
  26 }
  27
  28 static struct acpi_object_list *acpi_processor_alloc_pdc(void)
  29 {
  30         struct acpi_object_list *obj_list;
  31         union acpi_object *obj;
  32         u32 *buf;
  33
  34         /* allocate and initialize pdc. It will be used later. */
  35         obj_list = kmalloc(sizeof(struct acpi_object_list), GFP_KERNEL);
  36         if (!obj_list)
  37                 goto out;
  38
  39         obj = kmalloc(sizeof(union acpi_object), GFP_KERNEL);
  40         if (!obj) {
  41                 kfree(obj_list);
  42                 goto out;
  43         }
  44
  45         buf = kmalloc(12, GFP_KERNEL);
  46         if (!buf) {
  47                 kfree(obj);
  48                 kfree(obj_list);
  49                 goto out;
  50         }
  51
  52         acpi_set_pdc_bits(buf);
  53
  54         obj->type = ACPI_TYPE_BUFFER;
  55         obj->buffer.length = 12;
  56         obj->buffer.pointer = (u8 *) buf;
  57         obj_list->count = 1;
  58         obj_list->pointer = obj;
  59
  60         return obj_list;
  61 out:
  62         pr_err("Memory allocation error\n");
  63         return NULL;
  64 }
  65
  66 /*
  67  * _PDC is required for a BIOS-OS handshake for most of the newer
  68  * ACPI processor features.
  69  */
  70 static acpi_status
  71 acpi_processor_eval_pdc(acpi_handle handle, struct acpi_object_list *pdc_in)
  72 {
  73         acpi_status status = AE_OK;
  74
  75         status = acpi_evaluate_object(handle, "_PDC", pdc_in, NULL);
  76
  77         if (ACPI_FAILURE(status))
  78                 acpi_handle_debug(handle,
  79                     "Could not evaluate _PDC, using legacy perf control\n");
  80
  81         return status;
  82 }
  83
  84 void acpi_processor_set_pdc(acpi_handle handle)
  85 {
  86         struct acpi_object_list *obj_list;
  87
  88         if (arch_has_acpi_pdc() == false)
  89                 return;
  90
  91         obj_list = acpi_processor_alloc_pdc();
  92         if (!obj_list)
  93                 return;
  94
  95         acpi_processor_eval_pdc(handle, obj_list);
  96
  97         kfree(obj_list->pointer->buffer.pointer);
  98         kfree(obj_list->pointer);
  99         kfree(obj_list);
 100 }
 101
 102 static acpi_status __init
 103 early_init_pdc(acpi_handle handle, u32 lvl, void *context, void **rv)
 104 {
 105         if (processor_physically_present(handle) == false)
 106                 return AE_OK;
 107
 108         acpi_processor_set_pdc(handle);
 109         return AE_OK;
 110 }
 111
 112 void __init acpi_early_processor_set_pdc(void)
 113 {
 114         acpi_proc_quirk_mwait_check();
 115
 116         acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT,
 117                             ACPI_UINT32_MAX,
 118                             early_init_pdc, NULL, NULL, NULL);
 119         acpi_get_devices(ACPI_PROCESSOR_DEVICE_HID, early_init_pdc, NULL, NULL);
 120 }