2 * Copyright(c) 2015, 2016 Intel Corporation.
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.
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
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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.
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50 /* GUID for HFI1 variables in EFI */
51 #define HFI1_EFIVAR_GUID EFI_GUID(0xc50a953e, 0xa8b2, 0x42a6, \
52 0xbf, 0x89, 0xd3, 0x33, 0xa6, 0xe9, 0xe6, 0xd4)
53 /* largest EFI data size we expect */
54 #define EFI_DATA_SIZE 4096
57 * Read the named EFI variable. Return the size of the actual data in *size
58 * and a kmalloc'ed buffer in *return_data. The caller must free the
59 * data. It is guaranteed that *return_data will be NULL and *size = 0
60 * if this routine fails.
62 * Return 0 on success, -errno on failure.
64 static int read_efi_var(const char *name, unsigned long *size,
68 efi_char16_t *uni_name;
70 unsigned long temp_size;
76 /* set failure return values */
80 if (!efi_enabled(EFI_RUNTIME_SERVICES))
83 uni_name = kcalloc(strlen(name) + 1, sizeof(efi_char16_t), GFP_KERNEL);
84 temp_buffer = kzalloc(EFI_DATA_SIZE, GFP_KERNEL);
86 if (!uni_name || !temp_buffer) {
91 /* input: the size of the buffer */
92 temp_size = EFI_DATA_SIZE;
94 /* convert ASCII to unicode - it is a 1:1 mapping */
95 for (i = 0; name[i]; i++)
96 uni_name[i] = name[i];
98 /* need a variable for our GUID */
99 guid = HFI1_EFIVAR_GUID;
101 /* call into EFI runtime services */
102 status = efi.get_variable(
110 * It would be nice to call efi_status_to_err() here, but that
111 * is in the EFIVAR_FS code and may not be compiled in.
112 * However, even that is insufficient since it does not cover
113 * EFI_BUFFER_TOO_SMALL which could be an important return.
114 * For now, just split out succces or not found.
116 ret = status == EFI_SUCCESS ? 0 :
117 status == EFI_NOT_FOUND ? -ENOENT :
123 * We have successfully read the EFI variable into our
124 * temporary buffer. Now allocate a correctly sized
127 data = kmemdup(temp_buffer, temp_size, GFP_KERNEL);
144 * Read an HFI1 EFI variable of the form:
145 * <PCIe address>-<kind>
146 * Return an kalloc'ed array and size of the data.
148 * Returns 0 on success, -errno on failure.
150 int read_hfi1_efi_var(struct hfi1_devdata *dd, const char *kind,
151 unsigned long *size, void **return_data)
155 /* create a common prefix */
156 snprintf(name, sizeof(name), "%04x:%02x:%02x.%x-%s",
157 pci_domain_nr(dd->pcidev->bus),
158 dd->pcidev->bus->number,
159 PCI_SLOT(dd->pcidev->devfn),
160 PCI_FUNC(dd->pcidev->devfn),
163 return read_efi_var(name, size, return_data);