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);