1 files changed, 138 insertions, 0 deletions
diff --git a/drivers/infiniband/hw/hfi1/efivar.c b/drivers/infiniband/hw/hfi1/efivar.c
new file mode 100644
index 000000000..2b5d264f4
--- /dev/null
+++ b/drivers/infiniband/hw/hfi1/efivar.c
@@ -0,0 +1,138 @@
+// 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[128];
+	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;
+}