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/*
* cros_ec_vbc - Expose the vboot context nvram to userspace
*
* Copyright (C) 2015 Collabora Ltd.
*
* based on vendor driver,
*
* Copyright (C) 2012 The Chromium OS Authors
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/mfd/cros_ec.h>
#include <linux/mfd/cros_ec_commands.h>
#include <linux/module.h>
#include <linux/slab.h>
#define DRV_NAME "cros-ec-vbc"
static ssize_t vboot_context_read(struct file *filp, struct kobject *kobj,
struct bin_attribute *att, char *buf,
loff_t pos, size_t count)
{
struct device *dev = container_of(kobj, struct device, kobj);
struct cros_ec_dev *ec = to_cros_ec_dev(dev);
struct cros_ec_device *ecdev = ec->ec_dev;
struct ec_params_vbnvcontext *params;
struct cros_ec_command *msg;
int err;
const size_t para_sz = sizeof(params->op);
const size_t resp_sz = sizeof(struct ec_response_vbnvcontext);
const size_t payload = max(para_sz, resp_sz);
msg = kmalloc(sizeof(*msg) + payload, GFP_KERNEL);
if (!msg)
return -ENOMEM;
/* NB: we only kmalloc()ated enough space for the op field */
params = (struct ec_params_vbnvcontext *)msg->data;
params->op = EC_VBNV_CONTEXT_OP_READ;
msg->version = EC_VER_VBNV_CONTEXT;
msg->command = EC_CMD_VBNV_CONTEXT;
msg->outsize = para_sz;
msg->insize = resp_sz;
err = cros_ec_cmd_xfer(ecdev, msg);
if (err < 0) {
dev_err(dev, "Error sending read request: %d\n", err);
kfree(msg);
return err;
}
memcpy(buf, msg->data, resp_sz);
kfree(msg);
return resp_sz;
}
static ssize_t vboot_context_write(struct file *filp, struct kobject *kobj,
struct bin_attribute *attr, char *buf,
loff_t pos, size_t count)
{
struct device *dev = container_of(kobj, struct device, kobj);
struct cros_ec_dev *ec = to_cros_ec_dev(dev);
struct cros_ec_device *ecdev = ec->ec_dev;
struct ec_params_vbnvcontext *params;
struct cros_ec_command *msg;
int err;
const size_t para_sz = sizeof(*params);
const size_t data_sz = sizeof(params->block);
/* Only write full values */
if (count != data_sz)
return -EINVAL;
msg = kmalloc(sizeof(*msg) + para_sz, GFP_KERNEL);
if (!msg)
return -ENOMEM;
params = (struct ec_params_vbnvcontext *)msg->data;
params->op = EC_VBNV_CONTEXT_OP_WRITE;
memcpy(params->block, buf, data_sz);
msg->version = EC_VER_VBNV_CONTEXT;
msg->command = EC_CMD_VBNV_CONTEXT;
msg->outsize = para_sz;
msg->insize = 0;
err = cros_ec_cmd_xfer(ecdev, msg);
if (err < 0) {
dev_err(dev, "Error sending write request: %d\n", err);
kfree(msg);
return err;
}
kfree(msg);
return data_sz;
}
static umode_t cros_ec_vbc_is_visible(struct kobject *kobj,
struct bin_attribute *a, int n)
{
struct device *dev = container_of(kobj, struct device, kobj);
struct cros_ec_dev *ec = to_cros_ec_dev(dev);
struct device_node *np = ec->ec_dev->dev->of_node;
if (IS_ENABLED(CONFIG_OF) && np) {
if (of_property_read_bool(np, "google,has-vbc-nvram"))
return a->attr.mode;
}
return 0;
}
static BIN_ATTR_RW(vboot_context, 16);
static struct bin_attribute *cros_ec_vbc_bin_attrs[] = {
&bin_attr_vboot_context,
NULL
};
struct attribute_group cros_ec_vbc_attr_group = {
.name = "vbc",
.bin_attrs = cros_ec_vbc_bin_attrs,
.is_bin_visible = cros_ec_vbc_is_visible,
};
static int cros_ec_vbc_probe(struct platform_device *pd)
{
struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
struct device *dev = &pd->dev;
int ret;
ret = sysfs_create_group(&ec_dev->class_dev.kobj,
&cros_ec_vbc_attr_group);
if (ret < 0)
dev_err(dev, "failed to create %s attributes. err=%d\n",
cros_ec_vbc_attr_group.name, ret);
return ret;
}
static int cros_ec_vbc_remove(struct platform_device *pd)
{
struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
sysfs_remove_group(&ec_dev->class_dev.kobj,
&cros_ec_vbc_attr_group);
return 0;
}
static struct platform_driver cros_ec_vbc_driver = {
.driver = {
.name = DRV_NAME,
},
.probe = cros_ec_vbc_probe,
.remove = cros_ec_vbc_remove,
};
module_platform_driver(cros_ec_vbc_driver);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Expose the vboot context nvram to userspace");
MODULE_ALIAS("platform:" DRV_NAME);
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