1 // SPDX-License-Identifier: GPL-2.0-only
5 * Driver for exporting cbmem entries in sysfs.
7 * Copyright 2022 Google LLC
10 #include <linux/device.h>
11 #include <linux/init.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>
20 #include "coreboot_table.h"
27 static struct cbmem_entry *to_cbmem_entry(struct kobject *kobj)
29 return dev_get_drvdata(kobj_to_dev(kobj));
32 static ssize_t mem_read(struct file *filp, struct kobject *kobj,
33 struct bin_attribute *bin_attr, char *buf, loff_t pos,
36 struct cbmem_entry *entry = to_cbmem_entry(kobj);
38 return memory_read_from_buffer(buf, count, &pos, entry->mem_file_buf,
42 static ssize_t mem_write(struct file *filp, struct kobject *kobj,
43 struct bin_attribute *bin_attr, char *buf, loff_t pos,
46 struct cbmem_entry *entry = to_cbmem_entry(kobj);
48 if (pos < 0 || pos >= entry->size)
50 if (count > entry->size - pos)
51 count = entry->size - pos;
53 memcpy(entry->mem_file_buf + pos, buf, count);
56 static BIN_ATTR_ADMIN_RW(mem, 0);
58 static ssize_t address_show(struct device *dev, struct device_attribute *attr,
61 struct coreboot_device *cbdev = dev_to_coreboot_device(dev);
63 return sysfs_emit(buf, "0x%llx\n", cbdev->cbmem_entry.address);
65 static DEVICE_ATTR_RO(address);
67 static ssize_t size_show(struct device *dev, struct device_attribute *attr,
70 struct coreboot_device *cbdev = dev_to_coreboot_device(dev);
72 return sysfs_emit(buf, "0x%x\n", cbdev->cbmem_entry.entry_size);
74 static DEVICE_ATTR_RO(size);
76 static struct attribute *attrs[] = {
77 &dev_attr_address.attr,
82 static struct bin_attribute *bin_attrs[] = {
87 static const struct attribute_group cbmem_entry_group = {
89 .bin_attrs = bin_attrs,
92 static const struct attribute_group *dev_groups[] = {
97 static int cbmem_entry_probe(struct coreboot_device *dev)
99 struct cbmem_entry *entry;
101 entry = devm_kzalloc(&dev->dev, sizeof(*entry), GFP_KERNEL);
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,
109 if (IS_ERR(entry->mem_file_buf))
110 return PTR_ERR(entry->mem_file_buf);
112 entry->size = dev->cbmem_entry.entry_size;
117 static struct coreboot_driver cbmem_entry_driver = {
118 .probe = cbmem_entry_probe,
121 .owner = THIS_MODULE,
122 .dev_groups = dev_groups,
124 .tag = LB_TAG_CBMEM_ENTRY,
126 module_coreboot_driver(cbmem_entry_driver);
128 MODULE_AUTHOR("Jack Rosenthal <jrosenth@chromium.org>");
129 MODULE_LICENSE("GPL");