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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * cbmem.c4 *5 * Driver for exporting cbmem entries in sysfs.6 *7 * Copyright 2022 Google LLC8 */9 10#include <linux/device.h>11#include <linux/init.h>12#include <linux/io.h>13#include <linux/kernel.h>14#include <linux/kobject.h>15#include <linux/module.h>16#include <linux/platform_device.h>17#include <linux/slab.h>18#include <linux/sysfs.h>19 20#include "coreboot_table.h"21 22struct cbmem_entry {23 char *mem_file_buf;24 u32 size;25};26 27static struct cbmem_entry *to_cbmem_entry(struct kobject *kobj)28{29 return dev_get_drvdata(kobj_to_dev(kobj));30}31 32static ssize_t mem_read(struct file *filp, struct kobject *kobj,33 struct bin_attribute *bin_attr, char *buf, loff_t pos,34 size_t count)35{36 struct cbmem_entry *entry = to_cbmem_entry(kobj);37 38 return memory_read_from_buffer(buf, count, &pos, entry->mem_file_buf,39 entry->size);40}41 42static ssize_t mem_write(struct file *filp, struct kobject *kobj,43 struct bin_attribute *bin_attr, char *buf, loff_t pos,44 size_t count)45{46 struct cbmem_entry *entry = to_cbmem_entry(kobj);47 48 if (pos < 0 || pos >= entry->size)49 return -EINVAL;50 if (count > entry->size - pos)51 count = entry->size - pos;52 53 memcpy(entry->mem_file_buf + pos, buf, count);54 return count;55}56static BIN_ATTR_ADMIN_RW(mem, 0);57 58static ssize_t address_show(struct device *dev, struct device_attribute *attr,59 char *buf)60{61 struct coreboot_device *cbdev = dev_to_coreboot_device(dev);62 63 return sysfs_emit(buf, "0x%llx\n", cbdev->cbmem_entry.address);64}65static DEVICE_ATTR_RO(address);66 67static ssize_t size_show(struct device *dev, struct device_attribute *attr,68 char *buf)69{70 struct coreboot_device *cbdev = dev_to_coreboot_device(dev);71 72 return sysfs_emit(buf, "0x%x\n", cbdev->cbmem_entry.entry_size);73}74static DEVICE_ATTR_RO(size);75 76static struct attribute *attrs[] = {77 &dev_attr_address.attr,78 &dev_attr_size.attr,79 NULL,80};81 82static struct bin_attribute *bin_attrs[] = {83 &bin_attr_mem,84 NULL,85};86 87static const struct attribute_group cbmem_entry_group = {88 .attrs = attrs,89 .bin_attrs = bin_attrs,90};91 92static const struct attribute_group *dev_groups[] = {93 &cbmem_entry_group,94 NULL,95};96 97static int cbmem_entry_probe(struct coreboot_device *dev)98{99 struct cbmem_entry *entry;100 101 entry = devm_kzalloc(&dev->dev, sizeof(*entry), GFP_KERNEL);102 if (!entry)103 return -ENOMEM;104 105 dev_set_drvdata(&dev->dev, entry);106 entry->mem_file_buf = devm_memremap(&dev->dev, dev->cbmem_entry.address,107 dev->cbmem_entry.entry_size,108 MEMREMAP_WB);109 if (IS_ERR(entry->mem_file_buf))110 return PTR_ERR(entry->mem_file_buf);111 112 entry->size = dev->cbmem_entry.entry_size;113 114 return 0;115}116 117static const struct coreboot_device_id cbmem_ids[] = {118 { .tag = LB_TAG_CBMEM_ENTRY },119 { /* sentinel */ }120};121MODULE_DEVICE_TABLE(coreboot, cbmem_ids);122 123static struct coreboot_driver cbmem_entry_driver = {124 .probe = cbmem_entry_probe,125 .drv = {126 .name = "cbmem",127 .dev_groups = dev_groups,128 },129 .id_table = cbmem_ids,130};131module_coreboot_driver(cbmem_entry_driver);132 133MODULE_AUTHOR("Jack Rosenthal <jrosenth@chromium.org>");134MODULE_DESCRIPTION("Driver for exporting CBMEM entries in sysfs");135MODULE_LICENSE("GPL");136