1// SPDX-License-Identifier: GPL-2.0+
2// Expose the vboot context nvram to userspace
3//
4// Copyright (C) 2012 Google, Inc.
5// Copyright (C) 2015 Collabora Ltd.
6
7#include <linux/of.h>
8#include <linux/platform_device.h>
9#include <linux/module.h>
10#include <linux/platform_data/cros_ec_commands.h>
11#include <linux/platform_data/cros_ec_proto.h>
12#include <linux/slab.h>
13
14#define DRV_NAME "cros-ec-vbc"
15
16static ssize_t vboot_context_read(struct file *filp, struct kobject *kobj,
17				  struct bin_attribute *att, char *buf,
18				  loff_t pos, size_t count)
19{
20	struct device *dev = kobj_to_dev(kobj);
21	struct cros_ec_dev *ec = to_cros_ec_dev(dev);
22	struct cros_ec_device *ecdev = ec->ec_dev;
23	struct ec_params_vbnvcontext *params;
24	struct cros_ec_command *msg;
25	int err;
26	const size_t para_sz = sizeof(params->op);
27	const size_t resp_sz = sizeof(struct ec_response_vbnvcontext);
28	const size_t payload = max(para_sz, resp_sz);
29
30	msg = kmalloc(sizeof(*msg) + payload, GFP_KERNEL);
31	if (!msg)
32		return -ENOMEM;
33
34	/* NB: we only kmalloc()ated enough space for the op field */
35	params = (struct ec_params_vbnvcontext *)msg->data;
36	params->op = EC_VBNV_CONTEXT_OP_READ;
37
38	msg->version = EC_VER_VBNV_CONTEXT;
39	msg->command = EC_CMD_VBNV_CONTEXT;
40	msg->outsize = para_sz;
41	msg->insize = resp_sz;
42
43	err = cros_ec_cmd_xfer_status(ecdev, msg);
44	if (err < 0) {
45		dev_err(dev, "Error sending read request: %d\n", err);
46		kfree(msg);
47		return err;
48	}
49
50	memcpy(buf, msg->data, resp_sz);
51
52	kfree(msg);
53	return resp_sz;
54}
55
56static ssize_t vboot_context_write(struct file *filp, struct kobject *kobj,
57				   struct bin_attribute *attr, char *buf,
58				   loff_t pos, size_t count)
59{
60	struct device *dev = kobj_to_dev(kobj);
61	struct cros_ec_dev *ec = to_cros_ec_dev(dev);
62	struct cros_ec_device *ecdev = ec->ec_dev;
63	struct ec_params_vbnvcontext *params;
64	struct cros_ec_command *msg;
65	int err;
66	const size_t para_sz = sizeof(*params);
67	const size_t data_sz = sizeof(params->block);
68
69	/* Only write full values */
70	if (count != data_sz)
71		return -EINVAL;
72
73	msg = kmalloc(sizeof(*msg) + para_sz, GFP_KERNEL);
74	if (!msg)
75		return -ENOMEM;
76
77	params = (struct ec_params_vbnvcontext *)msg->data;
78	params->op = EC_VBNV_CONTEXT_OP_WRITE;
79	memcpy(params->block, buf, data_sz);
80
81	msg->version = EC_VER_VBNV_CONTEXT;
82	msg->command = EC_CMD_VBNV_CONTEXT;
83	msg->outsize = para_sz;
84	msg->insize = 0;
85
86	err = cros_ec_cmd_xfer_status(ecdev, msg);
87	if (err < 0) {
88		dev_err(dev, "Error sending write request: %d\n", err);
89		kfree(msg);
90		return err;
91	}
92
93	kfree(msg);
94	return data_sz;
95}
96
97static BIN_ATTR_RW(vboot_context, 16);
98
99static struct bin_attribute *cros_ec_vbc_bin_attrs[] = {
100	&bin_attr_vboot_context,
101	NULL
102};
103
104static struct attribute_group cros_ec_vbc_attr_group = {
105	.name = "vbc",
106	.bin_attrs = cros_ec_vbc_bin_attrs,
107};
108
109static int cros_ec_vbc_probe(struct platform_device *pd)
110{
111	struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
112	struct device *dev = &pd->dev;
113	int ret;
114
115	ret = sysfs_create_group(&ec_dev->class_dev.kobj,
116				 &cros_ec_vbc_attr_group);
117	if (ret < 0)
118		dev_err(dev, "failed to create %s attributes. err=%d\n",
119			cros_ec_vbc_attr_group.name, ret);
120
121	return ret;
122}
123
124static int cros_ec_vbc_remove(struct platform_device *pd)
125{
126	struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
127
128	sysfs_remove_group(&ec_dev->class_dev.kobj,
129			   &cros_ec_vbc_attr_group);
130
131	return 0;
132}
133
134static struct platform_driver cros_ec_vbc_driver = {
135	.driver = {
136		.name = DRV_NAME,
137	},
138	.probe = cros_ec_vbc_probe,
139	.remove = cros_ec_vbc_remove,
140};
141
142module_platform_driver(cros_ec_vbc_driver);
143
144MODULE_LICENSE("GPL");
145MODULE_DESCRIPTION("Expose the vboot context nvram to userspace");
146MODULE_ALIAS("platform:" DRV_NAME);
147