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Commit 18800fc7 authored by Emilio López's avatar Emilio López Committed by Olof Johansson
Browse files

platform/chrome: Support reading/writing the vboot context 



Some EC implementations include a small nvram space used to store
verified boot context data. This patch offers a way to expose this
data to userspace.

Reviewed-by: default avatarJavier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: default avatarEmilio López <emilio.lopez@collabora.co.uk>
Signed-off-by: default avatarOlof Johansson <olof@lixom.net>
parent 7f5028cf

drivers/platform/chrome/Makefile

+2 −1
Original line number Diff line number Diff line 


obj-$(CONFIG_CHROMEOS_LAPTOP)	+= chromeos_laptop.o

obj-$(CONFIG_CHROMEOS_PSTORE)	+= chromeos_pstore.o

cros_ec_devs-objs               := cros_ec_dev.o cros_ec_sysfs.o cros_ec_lightbar.o

cros_ec_devs-objs		:= cros_ec_dev.o cros_ec_sysfs.o \

				   cros_ec_lightbar.o cros_ec_vbc.o

obj-$(CONFIG_CROS_EC_CHARDEV)   += cros_ec_devs.o

obj-$(CONFIG_CROS_EC_LPC)       += cros_ec_lpc.o

obj-$(CONFIG_CROS_EC_PROTO)	+= cros_ec_proto.o

drivers/platform/chrome/cros_ec_dev.c

+1 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ static int ec_major; 
static const struct attribute_group *cros_ec_groups[] = {

	&cros_ec_attr_group,

	&cros_ec_lightbar_attr_group,

	&cros_ec_vbc_attr_group,

	NULL,

};

drivers/platform/chrome/cros_ec_vbc.c

0 → 100644
+137 −0
Original line number Diff line number Diff line 
/*

 * 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/slab.h>



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 = container_of(dev, struct cros_ec_dev,

					      class_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 = container_of(dev, struct cros_ec_dev,

					      class_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 = container_of(dev, struct cros_ec_dev,

					      class_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,

};

include/linux/mfd/cros_ec.h

+1 −0
Original line number Diff line number Diff line
@@ -255,5 +255,6 @@ int cros_ec_query_all(struct cros_ec_device *ec_dev); 
/* sysfs stuff */

extern struct attribute_group cros_ec_attr_group;

extern struct attribute_group cros_ec_lightbar_attr_group;

extern struct attribute_group cros_ec_vbc_attr_group;



#endif /* __LINUX_MFD_CROS_EC_H */