path: root/drivers/visorbus/visorbus_main.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright � 2010 - 2015 UNISYS CORPORATION
 * All rights reserved.
 */

#include <linux/ctype.h>
#include <linux/debugfs.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/visorbus.h>
#include <linux/uuid.h>

#include "visorbus_private.h"

static const guid_t visor_vbus_channel_guid = VISOR_VBUS_CHANNEL_GUID;

/* Display string that is guaranteed to be no longer the 99 characters */
#define LINESIZE 99
#define POLLJIFFIES_NORMALCHANNEL 10

/* stores whether bus_registration was successful */
static bool initialized;
static struct dentry *visorbus_debugfs_dir;

/*
 * DEVICE type attributes
 *
 * The modalias file will contain the guid of the device.
 */
static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
			     char *buf)
{
	struct visor_device *vdev;
	const guid_t *guid;

	vdev = to_visor_device(dev);
	guid = visorchannel_get_guid(vdev->visorchannel);
	return sprintf(buf, "visorbus:%pUl\n", guid);
}
static DEVICE_ATTR_RO(modalias);

static struct attribute *visorbus_dev_attrs[] = {
	&dev_attr_modalias.attr,
	NULL,
};

ATTRIBUTE_GROUPS(visorbus_dev);

/* filled in with info about parent chipset driver when we register with it */
static struct visor_vbus_deviceinfo chipset_driverinfo;
/* filled in with info about this driver, wrt it servicing client busses */
static struct visor_vbus_deviceinfo clientbus_driverinfo;

/* list of visor_device structs, linked via .list_all */
static LIST_HEAD(list_all_bus_instances);
/* list of visor_device structs, linked via .list_all */
static LIST_HEAD(list_all_device_instances);

/*
 * Generic function useful for validating any type of channel when it is
 * received by the client that will be accessing the channel.
 * Note that <logCtx> is only needed for callers in the EFI environment, and
 * is used to pass the EFI_DIAG_CAPTURE_PROTOCOL needed to log messages.
 */
int visor_check_channel(struct channel_header *ch, struct device *dev,
			const guid_t *expected_guid, char *chname,
			u64 expected_min_bytes, u32 expected_version,
			u64 expected_signature)
{
	if (!guid_is_null(expected_guid)) {
		/* caller wants us to verify type GUID */
		if (!guid_equal(&ch->chtype, expected_guid)) {
			dev_err(dev, "Channel mismatch on channel=%s(%pUL) field=type expected=%pUL actual=%pUL\n",
				chname, expected_guid, expected_guid,
				&ch->chtype);
			return 0;
		}
	}
	/* verify channel size */
	if (expected_min_bytes > 0) {
		if (ch->size < expected_min_bytes) {
			dev_err(dev, "Channel mismatch on channel=%s(%pUL) field=size expected=0x%-8.8Lx actual=0x%-8.8Lx\n",
				chname, expected_guid,
				(unsigned long long)expected_min_bytes,
				ch->size);
			return 0;
		}
	}
	/* verify channel version */
	if (expected_version > 0) {
		if (ch->version_id != expected_version) {
			dev_err(dev, "Channel mismatch on channel=%s(%pUL) field=version expected=0x%-8.8lx actual=0x%-8.8x\n",
				chname, expected_guid,
				(unsigned long)expected_version,
				ch->version_id);
			return 0;
		}
	}
	/* verify channel signature */
	if (expected_signature > 0) {
		if (ch->signature != expected_signature) {
			dev_err(dev, "Channel mismatch on channel=%s(%pUL) field=signature expected=0x%-8.8Lx actual=0x%-8.8Lx\n",
				chname, expected_guid,	expected_signature,
				ch->signature);
			return 0;
		}
	}
	return 1;
}

static int visorbus_uevent(struct device *xdev, struct kobj_uevent_env *env)
{
	struct visor_device *dev;
	const guid_t *guid;

	dev = to_visor_device(xdev);
	guid = visorchannel_get_guid(dev->visorchannel);
	return add_uevent_var(env, "MODALIAS=visorbus:%pUl", guid);
}

/*
 * visorbus_match() - called automatically upon adding a visor_device
 *                    (device_add), or adding a visor_driver
 *                    (visorbus_register_visor_driver)
 * @xdev: struct device for the device being matched
 * @xdrv: struct device_driver for driver to match device against
 *
 * Return: 1 iff the provided driver can control the specified device
 */
static int visorbus_match(struct device *xdev, struct de