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 cros_ec_command *msg;
24	/*
25	 * This should be a pointer to the same type as op field in
26	 * struct ec_params_vbnvcontext.
27	 */
28	uint32_t *params_op;
29	int err;
30	const size_t para_sz = sizeof(*params_op);
31	const size_t resp_sz = sizeof(struct ec_response_vbnvcontext);
32	const size_t payload = max(para_sz, resp_sz);
33
34	msg = kmalloc(sizeof(*msg) + payload, GFP_KERNEL);
35	if (!msg)
36		return -ENOMEM;
37
38	/* NB: we only kmalloc()ated enough space for the op field */
39	params_op = (uint32_t *)msg->data;
40	*params_op = EC_VBNV_CONTEXT_OP_READ;
41
42	msg->version = EC_VER_VBNV_CONTEXT;
43	msg->command = EC_CMD_VBNV_CONTEXT;
44	msg->outsize = para_sz;
45	msg->insize = resp_sz;
46
47	err = cros_ec_cmd_xfer_status(ecdev, msg);
48	if (err < 0) {
49		dev_err(dev, "Error sending read request: %d\n", err);
50		kfree(msg);
51		return err;
52	}
53
54	memcpy(buf, msg->data, resp_sz);
55
56	kfree(msg);
57	return resp_sz;
58}
59
60static ssize_t vboot_context_write(struct file *filp, struct kobject *kobj,
61				   struct bin_attribute *attr, char *buf,
62				   loff_t pos, size_t count)
63{
64	struct device *dev = kobj_to_dev(kobj);
65	struct cros_ec_dev *ec = to_cros_ec_dev(dev);
66	struct cros_ec_device *ecdev = ec->ec_dev;
67	struct ec_params_vbnvcontext *params;
68	struct cros_ec_command *msg;
69	int err;
70	const size_t para_sz = sizeof(*params);
71	const size_t data_sz = sizeof(params->block);
72
73	/* Only write full values */
74	if (count != data_sz)
75		return -EINVAL;
76
77	msg = kmalloc(sizeof(*msg) + para_sz, GFP_KERNEL);
78	if (!msg)
79		return -ENOMEM;
80
81	params = (struct ec_params_vbnvcontext *)msg->data;
82	params->op = EC_VBNV_CONTEXT_OP_WRITE;
83	memcpy(params->block, buf, data_sz);
84
85	msg->version = EC_VER_VBNV_CONTEXT;
86	msg->command = EC_CMD_VBNV_CONTEXT;
87	msg->outsize = para_sz;
88	msg->insize = 0;
89
90	err = cros_ec_cmd_xfer_status(ecdev, msg);
91	if (err < 0) {
92		dev_err(dev, "Error sending write request: %d\n", err);
93		kfree(msg);
94		return err;
95	}
96
97	kfree(msg);
98	return data_sz;
99}
100
101static BIN_ATTR_RW(vboot_context, 16);
102
103static struct bin_attribute *cros_ec_vbc_bin_attrs[] = {
104	&bin_attr_vboot_context,
105	NULL
106};
107
108static const struct attribute_group cros_ec_vbc_attr_group = {
109	.name = "vbc",
110	.bin_attrs = cros_ec_vbc_bin_attrs,
111};
112
113static int cros_ec_vbc_probe(struct platform_device *pd)
114{
115	struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
116	struct device *dev = &pd->dev;
117	int ret;
118
119	ret = sysfs_create_group(&ec_dev->class_dev.kobj,
120				 &cros_ec_vbc_attr_group);
121	if (ret < 0)
122		dev_err(dev, "failed to create %s attributes. err=%d\n",
123			cros_ec_vbc_attr_group.name, ret);
124
125	return ret;
126}
127
128static void cros_ec_vbc_remove(struct platform_device *pd)
129{
130	struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
131
132	sysfs_remove_group(&ec_dev->class_dev.kobj,
133			   &cros_ec_vbc_attr_group);
134}
135
136static struct platform_driver cros_ec_vbc_driver = {
137	.driver = {
138		.name = DRV_NAME,
139	},
140	.probe = cros_ec_vbc_probe,
141	.remove_new = cros_ec_vbc_remove,
142};
143
144module_platform_driver(cros_ec_vbc_driver);
145
146MODULE_LICENSE("GPL");
147MODULE_DESCRIPTION("Expose the vboot context nvram to userspace");
148MODULE_ALIAS("platform:" DRV_NAME);
149