Skip to content

Commit 18800fc

Browse files
elopezolofj
elopez
authored and
olofj
committed
platform/chrome: Support reading/writing the vboot context
Some EC implementations include a small nvram space used to store verified boot context data. This patch offers a way to expose this data to userspace. Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com> Signed-off-by: Emilio López <emilio.lopez@collabora.co.uk> Signed-off-by: Olof Johansson <olof@lixom.net>
1 parent 7f5028c commit 18800fc

4 files changed

Lines changed: 141 additions & 1 deletion

File tree

‎drivers/platform/chrome/Makefile‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,8 @@
11

22
obj-$(CONFIG_CHROMEOS_LAPTOP) += chromeos_laptop.o
33
obj-$(CONFIG_CHROMEOS_PSTORE) += chromeos_pstore.o
4-
cros_ec_devs-objs := cros_ec_dev.o cros_ec_sysfs.o cros_ec_lightbar.o
4+
cros_ec_devs-objs := cros_ec_dev.o cros_ec_sysfs.o \
5+
cros_ec_lightbar.o cros_ec_vbc.o
56
obj-$(CONFIG_CROS_EC_CHARDEV) += cros_ec_devs.o
67
obj-$(CONFIG_CROS_EC_LPC) += cros_ec_lpc.o
78
obj-$(CONFIG_CROS_EC_PROTO) += cros_ec_proto.o

‎drivers/platform/chrome/cros_ec_dev.c‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -32,6 +32,7 @@ static int ec_major;
3232
static const struct attribute_group *cros_ec_groups[] = {
3333
&cros_ec_attr_group,
3434
&cros_ec_lightbar_attr_group,
35+
&cros_ec_vbc_attr_group,
3536
NULL,
3637
};
3738

‎drivers/platform/chrome/cros_ec_vbc.c‎

Lines changed: 137 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,137 @@
1+
/*
2+
* cros_ec_vbc - Expose the vboot context nvram to userspace
3+
*
4+
* Copyright (C) 2015 Collabora Ltd.
5+
*
6+
* based on vendor driver,
7+
*
8+
* Copyright (C) 2012 The Chromium OS Authors
9+
*
10+
* This program is free software; you can redistribute it and/or modify
11+
* it under the terms of the GNU General Public License as published by
12+
* the Free Software Foundation; either version 2 of the License, or
13+
* (at your option) any later version.
14+
*
15+
* This program is distributed in the hope that it will be useful,
16+
* but WITHOUT ANY WARRANTY; without even the implied warranty of
17+
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18+
* GNU General Public License for more details.
19+
*/
20+
21+
#include <linux/of.h>
22+
#include <linux/platform_device.h>
23+
#include <linux/mfd/cros_ec.h>
24+
#include <linux/mfd/cros_ec_commands.h>
25+
#include <linux/slab.h>
26+
27+
static ssize_t vboot_context_read(struct file *filp, struct kobject *kobj,
28+
struct bin_attribute *att, char *buf,
29+
loff_t pos, size_t count)
30+
{
31+
struct device *dev = container_of(kobj, struct device, kobj);
32+
struct cros_ec_dev *ec = container_of(dev, struct cros_ec_dev,
33+
class_dev);
34+
struct cros_ec_device *ecdev = ec->ec_dev;
35+
struct ec_params_vbnvcontext *params;
36+
struct cros_ec_command *msg;
37+
int err;
38+
const size_t para_sz = sizeof(params->op);
39+
const size_t resp_sz = sizeof(struct ec_response_vbnvcontext);
40+
const size_t payload = max(para_sz, resp_sz);
41+
42+
msg = kmalloc(sizeof(*msg) + payload, GFP_KERNEL);
43+
if (!msg)
44+
return -ENOMEM;
45+
46+
/* NB: we only kmalloc()ated enough space for the op field */
47+
params = (struct ec_params_vbnvcontext *)msg->data;
48+
params->op = EC_VBNV_CONTEXT_OP_READ;
49+
50+
msg->version = EC_VER_VBNV_CONTEXT;
51+
msg->command = EC_CMD_VBNV_CONTEXT;
52+
msg->outsize = para_sz;
53+
msg->insize = resp_sz;
54+
55+
err = cros_ec_cmd_xfer(ecdev, msg);
56+
if (err < 0) {
57+
dev_err(dev, "Error sending read request: %d\n", err);
58+
kfree(msg);
59+
return err;
60+
}
61+
62+
memcpy(buf, msg->data, resp_sz);
63+
64+
kfree(msg);
65+
return resp_sz;
66+
}
67+
68+
static ssize_t vboot_context_write(struct file *filp, struct kobject *kobj,
69+
struct bin_attribute *attr, char *buf,
70+
loff_t pos, size_t count)
71+
{
72+
struct device *dev = container_of(kobj, struct device, kobj);
73+
struct cros_ec_dev *ec = container_of(dev, struct cros_ec_dev,
74+
class_dev);
75+
struct cros_ec_device *ecdev = ec->ec_dev;
76+
struct ec_params_vbnvcontext *params;
77+
struct cros_ec_command *msg;
78+
int err;
79+
const size_t para_sz = sizeof(*params);
80+
const size_t data_sz = sizeof(params->block);
81+
82+
/* Only write full values */
83+
if (count != data_sz)
84+
return -EINVAL;
85+
86+
msg = kmalloc(sizeof(*msg) + para_sz, GFP_KERNEL);
87+
if (!msg)
88+
return -ENOMEM;
89+
90+
params = (struct ec_params_vbnvcontext *)msg->data;
91+
params->op = EC_VBNV_CONTEXT_OP_WRITE;
92+
memcpy(params->block, buf, data_sz);
93+
94+
msg->version = EC_VER_VBNV_CONTEXT;
95+
msg->command = EC_CMD_VBNV_CONTEXT;
96+
msg->outsize = para_sz;
97+
msg->insize = 0;
98+
99+
err = cros_ec_cmd_xfer(ecdev, msg);
100+
if (err < 0) {
101+
dev_err(dev, "Error sending write request: %d\n", err);
102+
kfree(msg);
103+
return err;
104+
}
105+
106+
kfree(msg);
107+
return data_sz;
108+
}
109+
110+
static umode_t cros_ec_vbc_is_visible(struct kobject *kobj,
111+
struct bin_attribute *a, int n)
112+
{
113+
struct device *dev = container_of(kobj, struct device, kobj);
114+
struct cros_ec_dev *ec = container_of(dev, struct cros_ec_dev,
115+
class_dev);
116+
struct device_node *np = ec->ec_dev->dev->of_node;
117+
118+
if (IS_ENABLED(CONFIG_OF) && np) {
119+
if (of_property_read_bool(np, "google,has-vbc-nvram"))
120+
return a->attr.mode;
121+
}
122+
123+
return 0;
124+
}
125+
126+
static BIN_ATTR_RW(vboot_context, 16);
127+
128+
static struct bin_attribute *cros_ec_vbc_bin_attrs[] = {
129+
&bin_attr_vboot_context,
130+
NULL
131+
};
132+
133+
struct attribute_group cros_ec_vbc_attr_group = {
134+
.name = "vbc",
135+
.bin_attrs = cros_ec_vbc_bin_attrs,
136+
.is_bin_visible = cros_ec_vbc_is_visible,
137+
};

‎include/linux/mfd/cros_ec.h‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -255,5 +255,6 @@ int cros_ec_query_all(struct cros_ec_device *ec_dev);
255255
/* sysfs stuff */
256256
extern struct attribute_group cros_ec_attr_group;
257257
extern struct attribute_group cros_ec_lightbar_attr_group;
258+
extern struct attribute_group cros_ec_vbc_attr_group;
258259

259260
#endif /* __LINUX_MFD_CROS_EC_H */

0 commit comments

Comments
 (0)