linux-stable/drivers/staging/uwb/umc-bus.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Bus for UWB Multi-interface Controller capabilities.
 *
 * Copyright (C) 2007 Cambridge Silicon Radio Ltd.
 */
#include <linux/kernel.h>
#include <linux/sysfs.h>
#include <linux/workqueue.h>
#include <linux/module.h>
#include <linux/pci.h>
#include "include/umc.h"

static int umc_bus_pre_reset_helper(struct device *dev, void *data)
{
	int ret = 0;

	if (dev->driver) {
		struct umc_dev *umc = to_umc_dev(dev);
		struct umc_driver *umc_drv = to_umc_driver(dev->driver);

		if (umc_drv->pre_reset)
			ret = umc_drv->pre_reset(umc);
		else
			device_release_driver(dev);
	}
	return ret;
}

static int umc_bus_post_reset_helper(struct device *dev, void *data)
{
	int ret = 0;

	if (dev->driver) {
		struct umc_dev *umc = to_umc_dev(dev);
		struct umc_driver *umc_drv = to_umc_driver(dev->driver);

		if (umc_drv->post_reset)
			ret = umc_drv->post_reset(umc);
	} else
		ret = device_attach(dev);

	return ret;
}

/**
 * umc_controller_reset - reset the whole UMC controller
 * @umc: the UMC device for the radio controller.
 *
 * Drivers or all capabilities of the controller will have their
 * pre_reset methods called or be unbound from their device.  Then all
 * post_reset methods will be called or the drivers will be rebound.
 *
 * Radio controllers must provide pre_reset and post_reset methods and
 * reset the hardware in their start method.
 *
 * If this is called while a probe() or remove() is in progress it
 * will return -EAGAIN and not perform the reset.
 */
int umc_controller_reset(struct umc_dev *umc)
{
	struct device *parent = umc->dev.parent;
	int ret = 0;

	if (!device_trylock(parent))
		return -EAGAIN;
	ret = device_for_each_child(parent, parent, umc_bus_pre_reset_helper);
	if (ret >= 0)
		ret = device_for_each_child(parent, parent, umc_bus_post_reset_helper);
	device_unlock(parent);

	return ret;
}
EXPORT_SYMBOL_GPL(umc_controller_reset);

/**
 * umc_match_pci_id - match a UMC driver to a UMC device's parent PCI device.
 * @umc_drv: umc driver with match_data pointing to a zero-terminated
 * table of pci_device_id's.
 * @umc: umc device whose parent is to be matched.
 */
int umc_match_pci_id(struct umc_driver *umc_drv, struct umc_dev *umc)
{
	const struct pci_device_id *id_table = umc_drv->match_data;
	struct pci_dev *pci;

	if (!dev_is_pci(umc->dev.parent))
		return 0;

	pci = to_pci_dev(umc->dev.parent);
	return pci_match_id(id_table, pci) != NULL;
}
EXPORT_SYMBOL_GPL(umc_match_pci_id);

static int umc_bus_rescan_helper(struct device *dev, void *data)
{
	int ret = 0;

	if (!dev->driver)
		ret = device_attach(dev);

	return ret;
}

static void umc_bus_rescan(struct device *parent)
{
	int err;

	/*
	 * We can't use bus_rescan_devices() here as it deadlocks when
	 * it tries to retake the dev->parent semaphore.
	 */
	err = device_for_each_child(parent, NULL, umc_bus_rescan_helper);
	if (err < 0)
		printk(KERN_WARNING "%s: rescan of bus failed: %d\n",
		       KBUILD_MODNAME, err);
}

static int umc_bus_match(struct device *dev, struct device_driver *drv)
{
	struct umc_dev *umc = to_umc_dev(dev);
	struct umc_driver *umc_driver = to_umc_driver(drv);

	if (umc->cap_id == umc_driver->cap_id) {
		if (umc_driver->match)
			return umc_driver->match(umc_driver, umc);
		else
			return 1;
	}
	return 0;
}

static int umc_device_probe(struct device *dev)
{
	struct umc_dev *umc;
	struct umc_driver *umc_driver;
	int err;

	umc_driver = to_umc_driver(dev->driver);
	umc = to_umc_dev(dev);

	get_device(dev);
	err = umc_driver->probe(umc);
	if (err)
		put_device(dev);
	else
		umc_bus_rescan(dev->parent);

	return err;
}

static int umc_device_remove(struct device *dev)
{
	struct umc_dev *umc;
	struct umc_driver *umc_driver;

	umc_driver = to_umc_driver(dev->driver);
	umc = to_umc_dev(dev);

	umc_driver->remove(umc);
	put_device(dev);
	return 0;
}

static ssize_t capability_id_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct umc_dev *umc = to_umc_dev(dev);

	return sprintf(buf, "0x%02x\n", umc->cap_id);
}
static DEVICE_ATTR_RO(capability_id);

static ssize_t version_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct umc_dev *umc = to_umc_dev(dev);

	return sprintf(buf, "0x%04x\n", umc->version);
}
static DEVICE_ATTR_RO(version);

static struct attribute *umc_dev_attrs[] = {
	&dev_attr_capability_id.attr,
	&dev_attr_version.attr,
	NULL,
};
ATTRIBUTE_GROUPS(umc_dev);

struct bus_type umc_bus_type = {
	.name		= "umc",
	.match		= umc_bus_match,
	.probe		= umc_device_probe,
	.remove		= umc_device_remove,
	.dev_groups	= umc_dev_groups,
};
EXPORT_SYMBOL_GPL(umc_bus_type);

static int __init umc_bus_init(void)
{
	return bus_register(&umc_bus_type);
}
module_init(umc_bus_init);

static void __exit umc_bus_exit(void)
{
	bus_unregister(&umc_bus_type);
}
module_exit(umc_bus_exit);

MODULE_DESCRIPTION("UWB Multi-interface Controller capability bus");
MODULE_AUTHOR("Cambridge Silicon Radio Ltd.");
MODULE_LICENSE("GPL");