// 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/device-id/coreboot.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,			const 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,			 const 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 const 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 const struct bin_attribute *const 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");