mirror of https://gitee.com/openkylin/linux.git
148 lines
3.2 KiB
C
148 lines
3.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Export Runtime Configuration Interface Table Version 2 (RCI2)
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* to sysfs
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*
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* Copyright (C) 2019 Dell Inc
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* by Narendra K <Narendra.K@dell.com>
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*
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* System firmware advertises the address of the RCI2 Table via
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* an EFI Configuration Table entry. This code retrieves the RCI2
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* table from the address and exports it to sysfs as a binary
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* attribute 'rci2' under /sys/firmware/efi/tables directory.
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*/
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#include <linux/kobject.h>
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#include <linux/device.h>
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#include <linux/sysfs.h>
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#include <linux/efi.h>
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#include <linux/types.h>
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#include <linux/io.h>
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#define RCI_SIGNATURE "_RC_"
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struct rci2_table_global_hdr {
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u16 type;
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u16 resvd0;
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u16 hdr_len;
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u8 rci2_sig[4];
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u16 resvd1;
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u32 resvd2;
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u32 resvd3;
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u8 major_rev;
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u8 minor_rev;
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u16 num_of_structs;
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u32 rci2_len;
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u16 rci2_chksum;
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} __packed;
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static u8 *rci2_base;
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static u32 rci2_table_len;
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unsigned long rci2_table_phys __ro_after_init = EFI_INVALID_TABLE_ADDR;
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static ssize_t raw_table_read(struct file *file, struct kobject *kobj,
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struct bin_attribute *attr, char *buf,
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loff_t pos, size_t count)
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{
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memcpy(buf, attr->private + pos, count);
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return count;
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}
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static BIN_ATTR(rci2, S_IRUSR, raw_table_read, NULL, 0);
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static u16 checksum(void)
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{
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u8 len_is_odd = rci2_table_len % 2;
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u32 chksum_len = rci2_table_len;
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u16 *base = (u16 *)rci2_base;
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u8 buf[2] = {0};
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u32 offset = 0;
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u16 chksum = 0;
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if (len_is_odd)
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chksum_len -= 1;
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while (offset < chksum_len) {
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chksum += *base;
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offset += 2;
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base++;
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}
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if (len_is_odd) {
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buf[0] = *(u8 *)base;
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chksum += *(u16 *)(buf);
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}
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return chksum;
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}
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static int __init efi_rci2_sysfs_init(void)
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{
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struct kobject *tables_kobj;
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int ret = -ENOMEM;
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rci2_base = memremap(rci2_table_phys,
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sizeof(struct rci2_table_global_hdr),
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MEMREMAP_WB);
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if (!rci2_base) {
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pr_debug("RCI2 table init failed - could not map RCI2 table\n");
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goto err;
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}
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if (strncmp(rci2_base +
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offsetof(struct rci2_table_global_hdr, rci2_sig),
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RCI_SIGNATURE, 4)) {
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pr_debug("RCI2 table init failed - incorrect signature\n");
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ret = -ENODEV;
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goto err_unmap;
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}
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rci2_table_len = *(u32 *)(rci2_base +
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offsetof(struct rci2_table_global_hdr,
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rci2_len));
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memunmap(rci2_base);
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if (!rci2_table_len) {
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pr_debug("RCI2 table init failed - incorrect table length\n");
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goto err;
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}
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rci2_base = memremap(rci2_table_phys, rci2_table_len, MEMREMAP_WB);
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if (!rci2_base) {
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pr_debug("RCI2 table - could not map RCI2 table\n");
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goto err;
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}
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if (checksum() != 0) {
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pr_debug("RCI2 table - incorrect checksum\n");
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ret = -ENODEV;
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goto err_unmap;
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}
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tables_kobj = kobject_create_and_add("tables", efi_kobj);
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if (!tables_kobj) {
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pr_debug("RCI2 table - tables_kobj creation failed\n");
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goto err_unmap;
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}
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bin_attr_rci2.size = rci2_table_len;
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bin_attr_rci2.private = rci2_base;
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ret = sysfs_create_bin_file(tables_kobj, &bin_attr_rci2);
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if (ret != 0) {
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pr_debug("RCI2 table - rci2 sysfs bin file creation failed\n");
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kobject_del(tables_kobj);
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kobject_put(tables_kobj);
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goto err_unmap;
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}
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return 0;
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err_unmap:
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memunmap(rci2_base);
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err:
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pr_debug("RCI2 table - sysfs initialization failed\n");
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return ret;
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}
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late_initcall(efi_rci2_sysfs_init);
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