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
  23         /* Twiddle arch-specific bits needed for _PDC */
  24         arch_acpi_set_proc_cap_bits(&buf[2]);
  25 }
  26
  27 static struct acpi_object_list *acpi_processor_alloc_pdc(void)
  28 {
  29         struct acpi_object_list *obj_list;
  30         union acpi_object *obj;
  31         u32 *buf;
  32
  33         /* allocate and initialize pdc. It will be used later. */
  34         obj_list = kmalloc(sizeof(struct acpi_object_list), GFP_KERNEL);
  35         if (!obj_list)
  36                 goto out;
  37
  38         obj = kmalloc(sizeof(union acpi_object), GFP_KERNEL);
  39         if (!obj) {
  40                 kfree(obj_list);
  41                 goto out;
  42         }
  43
  44         buf = kmalloc(12, GFP_KERNEL);
  45         if (!buf) {
  46                 kfree(obj);
  47                 kfree(obj_list);
  48                 goto out;
  49         }
  50
  51         acpi_set_pdc_bits(buf);
  52
  53         obj->type = ACPI_TYPE_BUFFER;
  54         obj->buffer.length = 12;
  55         obj->buffer.pointer = (u8 *) buf;
  56         obj_list->count = 1;
  57         obj_list->pointer = obj;
  58
  59         return obj_list;
  60 out:
  61         pr_err("Memory allocation error\n");
  62         return NULL;
  63 }
  64
  65 /*
  66  * _PDC is required for a BIOS-OS handshake for most of the newer
  67  * ACPI processor features.
  68  */
  69 static acpi_status
  70 acpi_processor_eval_pdc(acpi_handle handle, struct acpi_object_list *pdc_in)
  71 {
  72         acpi_status status = AE_OK;
  73
  74         status = acpi_evaluate_object(handle, "_PDC", pdc_in, NULL);
  75
  76         if (ACPI_FAILURE(status))
  77                 acpi_handle_debug(handle,
  78                     "Could not evaluate _PDC, using legacy perf control\n");
  79
  80         return status;
  81 }
  82
  83 void acpi_processor_set_pdc(acpi_handle handle)
  84 {
  85         struct acpi_object_list *obj_list;
  86
  87         if (arch_has_acpi_pdc() == false)
  88                 return;
  89
  90         obj_list = acpi_processor_alloc_pdc();
  91         if (!obj_list)
  92                 return;
  93
  94         acpi_processor_eval_pdc(handle, obj_list);
  95
  96         kfree(obj_list->pointer->buffer.pointer);
  97         kfree(obj_list->pointer);
  98         kfree(obj_list);
  99 }
 100
 101 static acpi_status __init
 102 early_init_pdc(acpi_handle handle, u32 lvl, void *context, void **rv)
 103 {
 104         if (processor_physically_present(handle) == false)
 105                 return AE_OK;
 106
 107         acpi_processor_set_pdc(handle);
 108         return AE_OK;
 109 }
 110
 111 void __init acpi_early_processor_set_pdc(void)
 112 {
 113         acpi_proc_quirk_mwait_check();
 114
 115         acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT,
 116                             ACPI_UINT32_MAX,
 117                             early_init_pdc, NULL, NULL, NULL);
 118         acpi_get_devices(ACPI_PROCESSOR_DEVICE_HID, early_init_pdc, NULL, NULL);
 119 }