1 // SPDX-License-Identifier: GPL-2.0 or BSD-3-Clause
3 * Copyright(c) 2015, 2016 Intel Corporation.
6 #include <linux/ctype.h>
9 /* GUID for HFI1 variables in EFI */
10 #define HFI1_EFIVAR_GUID EFI_GUID(0xc50a953e, 0xa8b2, 0x42a6, \
11 0xbf, 0x89, 0xd3, 0x33, 0xa6, 0xe9, 0xe6, 0xd4)
12 /* largest EFI data size we expect */
13 #define EFI_DATA_SIZE 4096
16 * Read the named EFI variable. Return the size of the actual data in *size
17 * and a kmalloc'ed buffer in *return_data. The caller must free the
18 * data. It is guaranteed that *return_data will be NULL and *size = 0
19 * if this routine fails.
21 * Return 0 on success, -errno on failure.
23 static int read_efi_var(const char *name, unsigned long *size,
27 efi_char16_t *uni_name;
29 unsigned long temp_size;
35 /* set failure return values */
39 if (!efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE))
42 uni_name = kcalloc(strlen(name) + 1, sizeof(efi_char16_t), GFP_KERNEL);
43 temp_buffer = kzalloc(EFI_DATA_SIZE, GFP_KERNEL);
45 if (!uni_name || !temp_buffer) {
50 /* input: the size of the buffer */
51 temp_size = EFI_DATA_SIZE;
53 /* convert ASCII to unicode - it is a 1:1 mapping */
54 for (i = 0; name[i]; i++)
55 uni_name[i] = name[i];
57 /* need a variable for our GUID */
58 guid = HFI1_EFIVAR_GUID;
60 /* call into EFI runtime services */
61 status = efi.get_variable(
69 * It would be nice to call efi_status_to_err() here, but that
70 * is in the EFIVAR_FS code and may not be compiled in.
71 * However, even that is insufficient since it does not cover
72 * EFI_BUFFER_TOO_SMALL which could be an important return.
73 * For now, just split out succces or not found.
75 ret = status == EFI_SUCCESS ? 0 :
76 status == EFI_NOT_FOUND ? -ENOENT :
82 * We have successfully read the EFI variable into our
83 * temporary buffer. Now allocate a correctly sized
86 data = kmemdup(temp_buffer, temp_size, GFP_KERNEL);
103 * Read an HFI1 EFI variable of the form:
104 * <PCIe address>-<kind>
105 * Return an kalloc'ed array and size of the data.
107 * Returns 0 on success, -errno on failure.
109 int read_hfi1_efi_var(struct hfi1_devdata *dd, const char *kind,
110 unsigned long *size, void **return_data)
112 char prefix_name[64];
117 /* create a common prefix */
118 snprintf(prefix_name, sizeof(prefix_name), "%04x:%02x:%02x.%x",
119 pci_domain_nr(dd->pcidev->bus),
120 dd->pcidev->bus->number,
121 PCI_SLOT(dd->pcidev->devfn),
122 PCI_FUNC(dd->pcidev->devfn));
123 snprintf(name, sizeof(name), "%s-%s", prefix_name, kind);
124 result = read_efi_var(name, size, return_data);
127 * If reading the lowercase EFI variable fail, read the uppercase
131 /* Converting to uppercase */
132 for (i = 0; prefix_name[i]; i++)
133 if (isalpha(prefix_name[i]))
134 prefix_name[i] = toupper(prefix_name[i]);
135 snprintf(name, sizeof(name), "%s-%s", prefix_name, kind);
136 result = read_efi_var(name, size, return_data);