xref: /linux/drivers/platform/chrome/cros_ec_vbc.c (revision 621cde16e49b3ecf7d59a8106a20aaebfb4a59a9)
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 
vboot_context_read(struct file * filp,struct kobject * kobj,struct bin_attribute * att,char * buf,loff_t pos,size_t count)17 static ssize_t vboot_context_read(struct file *filp, struct kobject *kobj,
18 				  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(ecdev, msg);
49 	if (err < 0) {
50 		dev_err(dev, "Error sending read request: %d\n", err);
51 		kfree(msg);
52 		return err;
53 	}
54 
55 	memcpy(buf, msg->data, resp_sz);
56 
57 	kfree(msg);
58 	return resp_sz;
59 }
60 
vboot_context_write(struct file * filp,struct kobject * kobj,struct bin_attribute * attr,char * buf,loff_t pos,size_t count)61 static ssize_t vboot_context_write(struct file *filp, struct kobject *kobj,
62 				   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(ecdev, msg);
92 	if (err < 0) {
93 		dev_err(dev, "Error sending write request: %d\n", err);
94 		kfree(msg);
95 		return err;
96 	}
97 
98 	kfree(msg);
99 	return data_sz;
100 }
101 
102 static BIN_ATTR_RW(vboot_context, 16);
103 
104 static struct bin_attribute *cros_ec_vbc_bin_attrs[] = {
105 	&bin_attr_vboot_context,
106 	NULL
107 };
108 
109 static const struct attribute_group cros_ec_vbc_attr_group = {
110 	.name = "vbc",
111 	.bin_attrs = cros_ec_vbc_bin_attrs,
112 };
113 
cros_ec_vbc_probe(struct platform_device * pd)114 static int cros_ec_vbc_probe(struct platform_device *pd)
115 {
116 	struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
117 	struct device *dev = &pd->dev;
118 	int ret;
119 
120 	ret = sysfs_create_group(&ec_dev->class_dev.kobj,
121 				 &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 
cros_ec_vbc_remove(struct platform_device * pd)129 static void cros_ec_vbc_remove(struct platform_device *pd)
130 {
131 	struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
132 
133 	sysfs_remove_group(&ec_dev->class_dev.kobj,
134 			   &cros_ec_vbc_attr_group);
135 }
136 
137 static const struct platform_device_id cros_ec_vbc_id[] = {
138 	{ DRV_NAME, 0 },
139 	{}
140 };
141 MODULE_DEVICE_TABLE(platform, cros_ec_vbc_id);
142 
143 static struct platform_driver cros_ec_vbc_driver = {
144 	.driver = {
145 		.name = DRV_NAME,
146 	},
147 	.probe = cros_ec_vbc_probe,
148 	.remove_new = cros_ec_vbc_remove,
149 	.id_table = cros_ec_vbc_id,
150 };
151 
152 module_platform_driver(cros_ec_vbc_driver);
153 
154 MODULE_LICENSE("GPL");
155 MODULE_DESCRIPTION("Expose the vboot context nvram to userspace");
156