139 lines · c
1// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause2/*3 * Copyright(c) 2015, 2016 Intel Corporation.4 */5 6#include <linux/string.h>7#include <linux/string_helpers.h>8 9#include "efivar.h"10 11/* GUID for HFI1 variables in EFI */12#define HFI1_EFIVAR_GUID EFI_GUID(0xc50a953e, 0xa8b2, 0x42a6, \13 0xbf, 0x89, 0xd3, 0x33, 0xa6, 0xe9, 0xe6, 0xd4)14/* largest EFI data size we expect */15#define EFI_DATA_SIZE 409616 17/*18 * Read the named EFI variable. Return the size of the actual data in *size19 * and a kmalloc'ed buffer in *return_data. The caller must free the20 * data. It is guaranteed that *return_data will be NULL and *size = 021 * if this routine fails.22 *23 * Return 0 on success, -errno on failure.24 */25static int read_efi_var(const char *name, unsigned long *size,26 void **return_data)27{28 efi_status_t status;29 efi_char16_t *uni_name;30 efi_guid_t guid;31 unsigned long temp_size;32 void *temp_buffer;33 void *data;34 int i;35 int ret;36 37 /* set failure return values */38 *size = 0;39 *return_data = NULL;40 41 if (!efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE))42 return -EOPNOTSUPP;43 44 uni_name = kcalloc(strlen(name) + 1, sizeof(efi_char16_t), GFP_KERNEL);45 temp_buffer = kzalloc(EFI_DATA_SIZE, GFP_KERNEL);46 47 if (!uni_name || !temp_buffer) {48 ret = -ENOMEM;49 goto fail;50 }51 52 /* input: the size of the buffer */53 temp_size = EFI_DATA_SIZE;54 55 /* convert ASCII to unicode - it is a 1:1 mapping */56 for (i = 0; name[i]; i++)57 uni_name[i] = name[i];58 59 /* need a variable for our GUID */60 guid = HFI1_EFIVAR_GUID;61 62 /* call into EFI runtime services */63 status = efi.get_variable(64 uni_name,65 &guid,66 NULL,67 &temp_size,68 temp_buffer);69 70 /*71 * It would be nice to call efi_status_to_err() here, but that72 * is in the EFIVAR_FS code and may not be compiled in.73 * However, even that is insufficient since it does not cover74 * EFI_BUFFER_TOO_SMALL which could be an important return.75 * For now, just split out success or not found.76 */77 ret = status == EFI_SUCCESS ? 0 :78 status == EFI_NOT_FOUND ? -ENOENT :79 -EINVAL;80 if (ret)81 goto fail;82 83 /*84 * We have successfully read the EFI variable into our85 * temporary buffer. Now allocate a correctly sized86 * buffer.87 */88 data = kmemdup(temp_buffer, temp_size, GFP_KERNEL);89 if (!data) {90 ret = -ENOMEM;91 goto fail;92 }93 94 *size = temp_size;95 *return_data = data;96 97fail:98 kfree(uni_name);99 kfree(temp_buffer);100 101 return ret;102}103 104/*105 * Read an HFI1 EFI variable of the form:106 * <PCIe address>-<kind>107 * Return an kalloc'ed array and size of the data.108 *109 * Returns 0 on success, -errno on failure.110 */111int read_hfi1_efi_var(struct hfi1_devdata *dd, const char *kind,112 unsigned long *size, void **return_data)113{114 char prefix_name[64];115 char name[128];116 int result;117 118 /* create a common prefix */119 snprintf(prefix_name, sizeof(prefix_name), "%04x:%02x:%02x.%x",120 pci_domain_nr(dd->pcidev->bus),121 dd->pcidev->bus->number,122 PCI_SLOT(dd->pcidev->devfn),123 PCI_FUNC(dd->pcidev->devfn));124 snprintf(name, sizeof(name), "%s-%s", prefix_name, kind);125 result = read_efi_var(name, size, return_data);126 127 /*128 * If reading the lowercase EFI variable fail, read the uppercase129 * variable.130 */131 if (result) {132 string_upper(prefix_name, prefix_name);133 snprintf(name, sizeof(name), "%s-%s", prefix_name, kind);134 result = read_efi_var(name, size, return_data);135 }136 137 return result;138}139