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// SPDX-License-Identifier: GPL-2.0-only
/*
* cbmem.c
*
* Driver for exporting cbmem entries in sysfs.
*
* Copyright 2022 Google LLC
*/
#include <linux/device.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/kobject.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include "coreboot_table.h"
struct cbmem_entry {
char *mem_file_buf;
u32 size;
};
static struct cbmem_entry *to_cbmem_entry(struct kobject *kobj)
{
return dev_get_drvdata(kobj_to_dev(kobj));
}
static ssize_t mem_read(struct file *filp, struct kobject *kobj,
struct bin_attribute *bin_attr, char *buf, loff_t pos,
size_t count)
{
struct cbmem_entry *entry = to_cbmem_entry(kobj);
return memory_read_from_buffer(buf, count, &pos, entry->mem_file_buf,
entry->size);
}
static ssize_t mem_write(struct file *filp, struct kobject *kobj,
struct bin_attribute *bin_attr, char *buf, loff_t pos,
size_t count)
{
struct cbmem_entry *entry = to_cbmem_entry(kobj);
if (pos < 0 || pos >= entry->size)
return -EINVAL;
if (count > entry->size - pos)
count = entry->size - pos;
memcpy(entry->mem_file_buf + pos, buf, count);
return count;
}
static BIN_ATTR_ADMIN_RW(mem, 0);
static ssize_t address_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct coreboot_device *cbdev = dev_to_coreboot_device(dev);
return sysfs_emit(buf, "0x%llx\n", cbdev->cbmem_entry.address);
}
static DEVICE_ATTR_RO(address);
static ssize_t size_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct coreboot_device *cbdev = dev_to_coreboot_device(dev);
return sysfs_emit(buf, "0x%x\n", cbdev->cbmem_entry.entry_size);
}
static DEVICE_ATTR_RO(size);
static struct attribute *attrs[] = {
&dev_attr_address.attr,
&dev_attr_size.attr,
NULL,
};
static struct bin_attribute *bin_attrs[] = {
&bin_attr_mem,
NULL,
};
static const struct attribute_group cbmem_entry_group = {
.attrs = attrs,
.bin_attrs = bin_attrs,
};
static const struct attribute_group *dev_groups[] = {
&cbmem_entry_group,
NULL,
};
static int cbmem_entry_probe(struct coreboot_device *dev)
{
struct cbmem_entry *entry;
entry = devm_kzalloc(&dev->dev, sizeof(*entry), GFP_KERNEL);
if (!entry)
return -ENOMEM;
dev_set_drvdata(&dev->dev, entry);
entry->mem_file_buf = devm_memremap(&dev->dev, dev->cbmem_entry.address,
dev->cbmem_entry.entry_size,
MEMREMAP_WB);
if (IS_ERR(entry->mem_file_buf))
return PTR_ERR(entry->mem_file_buf);
entry->size = dev->cbmem_entry.entry_size;
return 0;
}
static const struct coreboot_device_id cbmem_ids[] = {
{ .tag = LB_TAG_CBMEM_ENTRY },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(coreboot, cbmem_ids);
static struct coreboot_driver cbmem_entry_driver = {
.probe = cbmem_entry_probe,
.drv = {
.name = "cbmem",
.dev_groups = dev_groups,
},
.id_table = cbmem_ids,
};
module_coreboot_driver(cbmem_entry_driver);
MODULE_AUTHOR("Jack Rosenthal <jrosenth@chromium.org>");
MODULE_DESCRIPTION("Driver for exporting CBMEM entries in sysfs");
MODULE_LICENSE("GPL");
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