// SPDX-License-Identifier: GPL-2.0-only
#include <common.h>
#include <linux/virtio.h>
#include <linux/spinlock.h>
#include <linux/virtio_config.h>
#include <module.h>
#include <linux/kernel.h>
#include <uapi/linux/virtio_ids.h>

static int status_show(struct param_d *param, void *_dev)
{
	struct virtio_device *dev = _dev;

	dev->status_param = dev->config->get_status(dev);
	return 0;
}

static struct param_d *virtio_dev_add_param_features(struct virtio_device *dev)
{
	struct param_d *param;
	unsigned int i;
	char *buf;
	int len = 0;

	buf = xmalloc(sizeof(dev->features)*8 + 1);

	/* We actually represent this as a bitstring, as it could be
	 * arbitrary length in future. */
	for (i = 0; i < sizeof(dev->features)*8; i++)
		len += sprintf(buf+len, "%c",
			       __virtio_test_bit(dev, i) ? '1' : '0');

	param = dev_add_param_string_fixed(&dev->dev, "features", buf);
	free(buf);

	return param;
}

static inline int virtio_id_match(const struct virtio_device *dev,
				  const struct virtio_device_id *id)
{
	if (id->device != dev->id.device && id->device != VIRTIO_DEV_ANY_ID)
		return 0;

	return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor == dev->id.vendor;
}

/* This looks through all the IDs a driver claims to support.  If any of them
 * match, we return 1 and the kernel will call virtio_dev_probe(). */
static int virtio_dev_match(struct device_d *_dv, struct driver_d *_dr)
{
	unsigned int i;
	struct virtio_device *dev = dev_to_virtio(_dv);
	const struct virtio_device_id *ids;

	ids = drv_to_virtio(_dr)->id_table;
	for (i = 0; ids[i].device; i++)
		if (virtio_id_match(dev, &ids[i]))
			return 0;

	return -1;
}

void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
					 unsigned int fbit)
{
	unsigned int i;
	struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver);

	for (i = 0; i < drv->feature_table_size; i++)
		if (drv->feature_table[i] == fbit)
			return;

	if (drv->feature_table_legacy) {
		for (i = 0; i < drv->feature_table_size_legacy; i++)
			if (drv->feature_table_legacy[i] == fbit)
				return;
	}

	BUG();
}
EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);

static void __virtio_config_changed(struct virtio_device *dev)
{
	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);

	if (!dev->config_enabled)
		dev->config_change_pending = true;
	else if (drv && drv->config_changed)
		drv->config_changed(dev);
}

void virtio_config_changed(struct virtio_device *dev)
{
	unsigned long flags;

	spin_lock_irqsave(&dev->config_lock, flags);
	__virtio_config_changed(dev);
	spin_unlock_irqrestore(&dev->config_lock, flags);
}
EXPORT_SYMBOL_GPL(virtio_config_changed);

void virtio_config_disable(struct virtio_device *dev)
{
	dev->config_enabled = false;
}
EXPORT_SYMBOL_GPL(virtio_config_disable);

void virtio_config_enable(struct virtio_device *dev)
{
	dev->config_enabled = true;
	if (dev->config_change_pending)
		__virtio_config_changed(dev);
	dev->config_change_pending = false;
}
EXPORT_SYMBOL_GPL(virtio_config_enable);

void virtio_add_status(struct virtio_device *dev, unsigned int status)
{
	dev->config->set_status(dev, dev->config->get_status(dev) | status);
}
EXPORT_SYMBOL_GPL(virtio_add_status);

int virtio_finalize_features(struct virtio_device *dev)
{
	int ret = dev->config->finalize_features(dev);
	unsigned status;

	if (ret)
		return ret;

	ret = arch_has_restricted_virtio_memory_access();
	if (ret) {
		if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
			dev_warn(&dev->dev,
				 "device must provide VIRTIO_F_VERSION_1\n");
			return -ENODEV;
		}

		if (!virtio_has_feature(dev, VIRTIO_F_ACCESS_PLATFORM)) {
			dev_warn(&dev->dev,
				 "device must provide VIRTIO_F_ACCESS_PLATFORM\n");
			return -ENODEV;
		}
	}

	if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1))
		return 0;

	virtio_add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK);
	status = dev->config->get_status(dev);
	if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) {
		dev_err(&dev->dev, "virtio: device refuses features: %x\n",
			status);
		return -ENODEV;
	}
	return 0;
}
EXPORT_SYMBOL_GPL(virtio_finalize_features);

int virtio_find_vqs(struct virtio_device *vdev, unsigned int nvqs,
		    struct virtqueue *vqs[])
{
	return vdev->config->find_vqs(vdev, nvqs, vqs);
}
EXPORT_SYMBOL_GPL(virtio_find_vqs);

static int virtio_dev_probe(struct device_d *_d)
{
	int err, i;
	struct virtio_device *dev = dev_to_virtio(_d);
	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
	u64 device_features;
	u64 driver_features;
	u64 driver_features_legacy;

	/* We have a driver! */
	virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);

	/* Figure out what features the device supports. */
	device_features = dev->config->get_features(dev);

	/* Figure out what features the driver supports. */
	driver_features = 0;
	for (i = 0; i < drv->feature_table_size; i++) {
		unsigned int f = drv->feature_table[i];
		BUG_ON(f >= 64);
		driver_features |= (1ULL << f);
	}

	/* Some drivers have a separate feature table for virtio v1.0 */
	if (drv->feature_table_legacy) {
		driver_features_legacy = 0;
		for (i = 0; i < drv->feature_table_size_legacy; i++) {
			unsigned int f = drv->feature_table_legacy[i];
			BUG_ON(f >= 64);
			driver_features_legacy |= (1ULL << f);
		}
	} else {
		driver_features_legacy = driver_features;
	}

	if (device_features & (1ULL << VIRTIO_F_VERSION_1))
		dev->features = driver_features & device_features;
	else
		dev->features = driver_features_legacy & device_features;

	/* Transport features always preserved to pass to finalize_features. */
	for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
		if (device_features & (1ULL << i))
			__virtio_set_bit(dev, i);

	if (drv->validate) {
		err = drv->validate(dev);
		if (err)
			goto err;
	}

	err = virtio_finalize_features(dev);
	if (err)
		goto err;

	err = drv->probe(dev);
	if (err)
		goto err;

	/* If probe didn't do it, mark device DRIVER_OK ourselves. */
	if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
		virtio_device_ready(dev);

	if (drv->scan)
		drv->scan(dev);

	virtio_config_enable(dev);

	return 0;
err:
	virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
	return err;

}

static void virtio_dev_remove(struct device_d *_d)
{
	struct virtio_device *dev = dev_to_virtio(_d);
	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);

	virtio_config_disable(dev);

	drv->remove(dev);

	WARN_ONCE(dev->config->get_status(dev), "Driver should have reset device");

	/* Acknowledge the device's existence again. */
	virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
}

static struct bus_type virtio_bus = {
	.name  = "virtio",
	.match = virtio_dev_match,
	.probe = virtio_dev_probe,
	.remove = virtio_dev_remove,
};

int virtio_driver_register(struct virtio_driver *driver)
{
	/* Catch this early. */
	BUG_ON(driver->feature_table_size && !driver->feature_table);
	driver->driver.bus = &virtio_bus;

	return register_driver(&driver->driver);
}
EXPORT_SYMBOL_GPL(virtio_driver_register);

/**
 * register_virtio_device - register virtio device
 * @dev        : virtio device to be registered
 *
 * On error, the caller must call put_device on &@dev->dev (and not kfree),
 * as another code path may have obtained a reference to @dev.
 *
 * Returns: 0 on suceess, -error on failure
 */
int register_virtio_device(struct virtio_device *dev)
{
	int err;

	dev->dev.bus = &virtio_bus;
	dev->dev.id = DEVICE_ID_DYNAMIC;
	dev->dev.name = "virtio";

	spin_lock_init(&dev->config_lock);
	dev->config_enabled = false;
	dev->config_change_pending = false;

	/* We always start by resetting the device, in case a previous
	 * driver messed it up.  This also tests that code path a little. */
	dev->config->reset(dev);

	/* Acknowledge that we've seen the device. */
	virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);

	INIT_LIST_HEAD(&dev->vqs);

	/*
	 * register_device() causes the bus infrastructure to look for a matching
	 * driver.
	 */
	err = register_device(&dev->dev);
	if (err)
		goto out;

	dev_add_param_uint32_ro(&dev->dev, "device", &dev->id.device, "0x%04x");
	dev_add_param_uint32_ro(&dev->dev, "vendor", &dev->id.vendor, "0x%04x");
	dev_add_param_uint32(&dev->dev, "status", param_set_readonly,
			     status_show, &dev->status_param, "0x%08x", dev);
	virtio_dev_add_param_features(dev);

out:
	if (err)
		virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
	return err;
}
EXPORT_SYMBOL_GPL(register_virtio_device);

bool is_virtio_device(struct device_d *dev)
{
	return dev->bus == &virtio_bus;
}
EXPORT_SYMBOL_GPL(is_virtio_device);

void unregister_virtio_device(struct virtio_device *dev)
{
	unregister_device(&dev->dev);
}
EXPORT_SYMBOL_GPL(unregister_virtio_device);

static int virtio_init(void)
{
	if (bus_register(&virtio_bus) != 0)
		panic("virtio bus registration failed");
	return 0;
}
core_initcall(virtio_init);

MODULE_LICENSE("GPL");
