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				  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
 61static 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
102static BIN_ATTR_RW(vboot_context, 16);
103
104static struct bin_attribute *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(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
129static 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
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");