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/mod_devicetable.h>
10#include <linux/module.h>
11#include <linux/platform_data/cros_ec_commands.h>
12#include <linux/platform_data/cros_ec_proto.h>
13#include <linux/slab.h>
14
15#define DRV_NAME "cros-ec-vbc"
16
17static ssize_t vboot_context_read(struct file *filp, struct kobject *kobj,
18 const struct bin_attribute *att, char *buf,
19 loff_t pos, size_t count)
20{
21 struct device *dev = kobj_to_dev(kobj);
22 struct cros_ec_dev *ec = to_cros_ec_dev(dev);
23 struct cros_ec_device *ecdev = ec->ec_dev;
24 struct cros_ec_command *msg;
25 /*
26 * This should be a pointer to the same type as op field in
27 * struct ec_params_vbnvcontext.
28 */
29 uint32_t *params_op;
30 int err;
31 const size_t para_sz = sizeof(*params_op);
32 const size_t resp_sz = sizeof(struct ec_response_vbnvcontext);
33 const size_t payload = max(para_sz, resp_sz);
34
35 msg = kmalloc(sizeof(*msg) + payload, GFP_KERNEL);
36 if (!msg)
37 return -ENOMEM;
38
39 /* NB: we only kmalloc()ated enough space for the op field */
40 params_op = (uint32_t *)msg->data;
41 *params_op = EC_VBNV_CONTEXT_OP_READ;
42
43 msg->version = EC_VER_VBNV_CONTEXT;
44 msg->command = EC_CMD_VBNV_CONTEXT;
45 msg->outsize = para_sz;
46 msg->insize = resp_sz;
47
48 err = cros_ec_cmd_xfer_status(ec_dev: ecdev, msg);
49 if (err < 0) {
50 dev_err(dev, "Error sending read request: %d\n", err);
51 kfree(objp: msg);
52 return err;
53 }
54
55 memcpy(buf, msg->data, resp_sz);
56
57 kfree(objp: msg);
58 return resp_sz;
59}
60
61static ssize_t vboot_context_write(struct file *filp, struct kobject *kobj,
62 const struct bin_attribute *attr, char *buf,
63 loff_t pos, size_t count)
64{
65 struct device *dev = kobj_to_dev(kobj);
66 struct cros_ec_dev *ec = to_cros_ec_dev(dev);
67 struct cros_ec_device *ecdev = ec->ec_dev;
68 struct ec_params_vbnvcontext *params;
69 struct cros_ec_command *msg;
70 int err;
71 const size_t para_sz = sizeof(*params);
72 const size_t data_sz = sizeof(params->block);
73
74 /* Only write full values */
75 if (count != data_sz)
76 return -EINVAL;
77
78 msg = kmalloc(sizeof(*msg) + para_sz, GFP_KERNEL);
79 if (!msg)
80 return -ENOMEM;
81
82 params = (struct ec_params_vbnvcontext *)msg->data;
83 params->op = EC_VBNV_CONTEXT_OP_WRITE;
84 memcpy(params->block, buf, data_sz);
85
86 msg->version = EC_VER_VBNV_CONTEXT;
87 msg->command = EC_CMD_VBNV_CONTEXT;
88 msg->outsize = para_sz;
89 msg->insize = 0;
90
91 err = cros_ec_cmd_xfer_status(ec_dev: ecdev, msg);
92 if (err < 0) {
93 dev_err(dev, "Error sending write request: %d\n", err);
94 kfree(objp: msg);
95 return err;
96 }
97
98 kfree(objp: msg);
99 return data_sz;
100}
101
102static const BIN_ATTR_RW(vboot_context, 16);
103
104static const struct bin_attribute *const cros_ec_vbc_bin_attrs[] = {
105 &bin_attr_vboot_context,
106 NULL
107};
108
109static const struct attribute_group cros_ec_vbc_attr_group = {
110 .name = "vbc",
111 .bin_attrs = cros_ec_vbc_bin_attrs,
112};
113
114static int cros_ec_vbc_probe(struct platform_device *pd)
115{
116 struct cros_ec_dev *ec_dev = dev_get_drvdata(dev: pd->dev.parent);
117 struct device *dev = &pd->dev;
118 int ret;
119
120 ret = sysfs_create_group(kobj: &ec_dev->class_dev.kobj,
121 grp: &cros_ec_vbc_attr_group);
122 if (ret < 0)
123 dev_err(dev, "failed to create %s attributes. err=%d\n",
124 cros_ec_vbc_attr_group.name, ret);
125
126 return ret;
127}
128
129static void cros_ec_vbc_remove(struct platform_device *pd)
130{
131 struct cros_ec_dev *ec_dev = dev_get_drvdata(dev: pd->dev.parent);
132
133 sysfs_remove_group(kobj: &ec_dev->class_dev.kobj,
134 grp: &cros_ec_vbc_attr_group);
135}
136
137static const struct platform_device_id cros_ec_vbc_id[] = {
138 { DRV_NAME, 0 },
139 {}
140};
141MODULE_DEVICE_TABLE(platform, cros_ec_vbc_id);
142
143static struct platform_driver cros_ec_vbc_driver = {
144 .driver = {
145 .name = DRV_NAME,
146 },
147 .probe = cros_ec_vbc_probe,
148 .remove = cros_ec_vbc_remove,
149 .id_table = cros_ec_vbc_id,
150};
151
152module_platform_driver(cros_ec_vbc_driver);
153
154MODULE_LICENSE("GPL");
155MODULE_DESCRIPTION("Expose the vboot context nvram to userspace");
156

source code of linux/drivers/platform/chrome/cros_ec_vbc.c