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// SPDX-License-Identifier: GPL-2.0 or BSD-3-Clause
/*
* Copyright(c) 2015, 2016 Intel Corporation.
*/
#include <linux/string.h>
#include <linux/string_helpers.h>
#include "efivar.h"
/* GUID for HFI1 variables in EFI */
#define HFI1_EFIVAR_GUID EFI_GUID(0xc50a953e, 0xa8b2, 0x42a6, \
0xbf, 0x89, 0xd3, 0x33, 0xa6, 0xe9, 0xe6, 0xd4)
/* largest EFI data size we expect */
#define EFI_DATA_SIZE 4096
/*
* Read the named EFI variable. Return the size of the actual data in *size
* and a kmalloc'ed buffer in *return_data. The caller must free the
* data. It is guaranteed that *return_data will be NULL and *size = 0
* if this routine fails.
*
* Return 0 on success, -errno on failure.
*/
static int read_efi_var(const char *name, unsigned long *size,
void **return_data)
{
efi_status_t status;
efi_char16_t *uni_name;
efi_guid_t guid;
unsigned long temp_size;
void *temp_buffer;
void *data;
int i;
int ret;
/* set failure return values */
*size = 0;
*return_data = NULL;
if (!efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE))
return -EOPNOTSUPP;
uni_name = kcalloc(strlen(name) + 1, sizeof(efi_char16_t), GFP_KERNEL);
temp_buffer = kzalloc(EFI_DATA_SIZE, GFP_KERNEL);
if (!uni_name || !temp_buffer) {
ret = -ENOMEM;
goto fail;
}
/* input: the size of the buffer */
temp_size = EFI_DATA_SIZE;
/* convert ASCII to unicode - it is a 1:1 mapping */
for (i = 0; name[i]; i++)
uni_name[i] = name[i];
/* need a variable for our GUID */
guid = HFI1_EFIVAR_GUID;
/* call into EFI runtime services */
status = efi.get_variable(
uni_name,
&guid,
NULL,
&temp_size,
temp_buffer);
/*
* It would be nice to call efi_status_to_err() here, but that
* is in the EFIVAR_FS code and may not be compiled in.
* However, even that is insufficient since it does not cover
* EFI_BUFFER_TOO_SMALL which could be an important return.
* For now, just split out success or not found.
*/
ret = status == EFI_SUCCESS ? 0 :
status == EFI_NOT_FOUND ? -ENOENT :
-EINVAL;
if (ret)
goto fail;
/*
* We have successfully read the EFI variable into our
* temporary buffer. Now allocate a correctly sized
* buffer.
*/
data = kmemdup(temp_buffer, temp_size, GFP_KERNEL);
if (!data) {
ret = -ENOMEM;
goto fail;
}
*size = temp_size;
*return_data = data;
fail:
kfree(uni_name);
kfree(temp_buffer);
return ret;
}
/*
* Read an HFI1 EFI variable of the form:
* <PCIe address>-<kind>
* Return an kalloc'ed array and size of the data.
*
* Returns 0 on success, -errno on failure.
*/
int read_hfi1_efi_var(struct hfi1_devdata *dd, const char *kind,
unsigned long *size, void **return_data)
{
char prefix_name[64];
char name[64];
int result;
/* create a common prefix */
snprintf(prefix_name, sizeof(prefix_name), "%04x:%02x:%02x.%x",
pci_domain_nr(dd->pcidev->bus),
dd->pcidev->bus->number,
PCI_SLOT(dd->pcidev->devfn),
PCI_FUNC(dd->pcidev->devfn));
snprintf(name, sizeof(name), "%s-%s", prefix_name, kind);
result = read_efi_var(name, size, return_data);
/*
* If reading the lowercase EFI variable fail, read the uppercase
* variable.
*/
if (result) {
string_upper(prefix_name, prefix_name);
snprintf(name, sizeof(name), "%s-%s", prefix_name, kind);
result = read_efi_var(name, size, return_data);
}
return result;
}
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