drivers/infiniband/hw/hfi1/efivar.c

   1 /*
   2  * Copyright(c) 2015, 2016 Intel Corporation.
   3  *
   4  * This file is provided under a dual BSD/GPLv2 license.  When using or
   5  * redistributing this file, you may do so under either license.
   6  *
   7  * GPL LICENSE SUMMARY
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of version 2 of the GNU General Public License as
  11  * published by the Free Software Foundation.
  12  *
  13  * This program is distributed in the hope that it will be useful, but
  14  * WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * General Public License for more details.
  17  *
  18  * BSD LICENSE
  19  *
  20  * Redistribution and use in source and binary forms, with or without
  21  * modification, are permitted provided that the following conditions
  22  * are met:
  23  *
  24  *  - Redistributions of source code must retain the above copyright
  25  *    notice, this list of conditions and the following disclaimer.
  26  *  - Redistributions in binary form must reproduce the above copyright
  27  *    notice, this list of conditions and the following disclaimer in
  28  *    the documentation and/or other materials provided with the
  29  *    distribution.
  30  *  - Neither the name of Intel Corporation nor the names of its
  31  *    contributors may be used to endorse or promote products derived
  32  *    from this software without specific prior written permission.
  33  *
  34  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  35  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  36  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  37  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  38  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  39  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  40  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  41  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  42  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  43  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  44  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  45  *
  46  */
  47
  48 #include <linux/ctype.h>
  49 #include "efivar.h"
  50
  51 /* GUID for HFI1 variables in EFI */
  52 #define HFI1_EFIVAR_GUID EFI_GUID(0xc50a953e, 0xa8b2, 0x42a6, \
  53                 0xbf, 0x89, 0xd3, 0x33, 0xa6, 0xe9, 0xe6, 0xd4)
  54 /* largest EFI data size we expect */
  55 #define EFI_DATA_SIZE 4096
  56
  57 /*
  58  * Read the named EFI variable.  Return the size of the actual data in *size
  59  * and a kmalloc'ed buffer in *return_data.  The caller must free the
  60  * data.  It is guaranteed that *return_data will be NULL and *size = 0
  61  * if this routine fails.
  62  *
  63  * Return 0 on success, -errno on failure.
  64  */
  65 static int read_efi_var(const char *name, unsigned long *size,
  66                         void **return_data)
  67 {
  68         efi_status_t status;
  69         efi_char16_t *uni_name;
  70         efi_guid_t guid;
  71         unsigned long temp_size;
  72         void *temp_buffer;
  73         void *data;
  74         int i;
  75         int ret;
  76
  77         /* set failure return values */
  78         *size = 0;
  79         *return_data = NULL;
  80
  81         if (!efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE))
  82                 return -EOPNOTSUPP;
  83
  84         uni_name = kcalloc(strlen(name) + 1, sizeof(efi_char16_t), GFP_KERNEL);
  85         temp_buffer = kzalloc(EFI_DATA_SIZE, GFP_KERNEL);
  86
  87         if (!uni_name || !temp_buffer) {
  88                 ret = -ENOMEM;
  89                 goto fail;
  90         }
  91
  92         /* input: the size of the buffer */
  93         temp_size = EFI_DATA_SIZE;
  94
  95         /* convert ASCII to unicode - it is a 1:1 mapping */
  96         for (i = 0; name[i]; i++)
  97                 uni_name[i] = name[i];
  98
  99         /* need a variable for our GUID */
 100         guid = HFI1_EFIVAR_GUID;
 101
 102         /* call into EFI runtime services */
 103         status = efi.get_variable(
 104                         uni_name,
 105                         &guid,
 106                         NULL,
 107                         &temp_size,
 108                         temp_buffer);
 109
 110         /*
 111          * It would be nice to call efi_status_to_err() here, but that
 112          * is in the EFIVAR_FS code and may not be compiled in.
 113          * However, even that is insufficient since it does not cover
 114          * EFI_BUFFER_TOO_SMALL which could be an important return.
 115          * For now, just split out succces or not found.
 116          */
 117         ret = status == EFI_SUCCESS   ? 0 :
 118               status == EFI_NOT_FOUND ? -ENOENT :
 119                                         -EINVAL;
 120         if (ret)
 121                 goto fail;
 122
 123         /*
 124          * We have successfully read the EFI variable into our
 125          * temporary buffer.  Now allocate a correctly sized
 126          * buffer.
 127          */
 128         data = kmemdup(temp_buffer, temp_size, GFP_KERNEL);
 129         if (!data) {
 130                 ret = -ENOMEM;
 131                 goto fail;
 132         }
 133
 134         *size = temp_size;
 135         *return_data = data;
 136
 137 fail:
 138         kfree(uni_name);
 139         kfree(temp_buffer);
 140
 141         return ret;
 142 }
 143
 144 /*
 145  * Read an HFI1 EFI variable of the form:
 146  *      <PCIe address>-<kind>
 147  * Return an kalloc'ed array and size of the data.
 148  *
 149  * Returns 0 on success, -errno on failure.
 150  */
 151 int read_hfi1_efi_var(struct hfi1_devdata *dd, const char *kind,
 152                       unsigned long *size, void **return_data)
 153 {
 154         char prefix_name[64];
 155         char name[64];
 156         int result;
 157         int i;
 158
 159         /* create a common prefix */
 160         snprintf(prefix_name, sizeof(prefix_name), "%04x:%02x:%02x.%x",
 161                  pci_domain_nr(dd->pcidev->bus),
 162                  dd->pcidev->bus->number,
 163                  PCI_SLOT(dd->pcidev->devfn),
 164                  PCI_FUNC(dd->pcidev->devfn));
 165         snprintf(name, sizeof(name), "%s-%s", prefix_name, kind);
 166         result = read_efi_var(name, size, return_data);
 167
 168         /*
 169          * If reading the lowercase EFI variable fail, read the uppercase
 170          * variable.
 171          */
 172         if (result) {
 173                 /* Converting to uppercase */
 174                 for (i = 0; prefix_name[i]; i++)
 175                         if (isalpha(prefix_name[i]))
 176                                 prefix_name[i] = toupper(prefix_name[i]);
 177                 snprintf(name, sizeof(name), "%s-%s", prefix_name, kind);
 178                 result = read_efi_var(name, size, return_data);
 179         }
 180
 181         return result;
 182 }