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/mfd/cros_ec.h>
10 #include <linux/mfd/cros_ec_commands.h>
11 #include <linux/module.h>
12 #include <linux/slab.h>
13 
14 #define DRV_NAME "cros-ec-vbc"
15 
16 static 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 = container_of(kobj, struct device, 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(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 
56 static 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 = container_of(kobj, struct device, 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(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 
97 static BIN_ATTR_RW(vboot_context, 16);
98 
99 static struct bin_attribute *cros_ec_vbc_bin_attrs[] = {
100 	&bin_attr_vboot_context,
101 	NULL
102 };
103 
104 static struct attribute_group cros_ec_vbc_attr_group = {
105 	.name = "vbc",
106 	.bin_attrs = cros_ec_vbc_bin_attrs,
107 };
108 
109 static 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 
124 static 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 
134 static 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 
142 module_platform_driver(cros_ec_vbc_driver);
143 
144 MODULE_LICENSE("GPL");
145 MODULE_DESCRIPTION("Expose the vboot context nvram to userspace");
146 MODULE_ALIAS("platform:" DRV_NAME);
147