/*
 * Copyright (c) 2013  Luis R. Rodriguez <mcgrof@do-not-panic.com>
 *
 * Linux backport symbols for kernels 3.10.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/proc_fs.h>
#include <linux/random.h>
#include <linux/tty.h>
#include <linux/pci.h>
#include <linux/pci_regs.h>
#include <linux/of.h>
#include <linux/mm.h>

void proc_set_size(struct proc_dir_entry *de, loff_t size)
{
	de->size = size;
}
EXPORT_SYMBOL_GPL(proc_set_size);

void proc_set_user(struct proc_dir_entry *de, kuid_t uid, kgid_t gid)
{
	de->uid = uid;
	de->gid = gid;
}
EXPORT_SYMBOL_GPL(proc_set_user);

/* get_random_int() was not exported for module use until 3.10-rc.
   Implement it here in terms of the more expensive get_random_bytes()
 */
unsigned int get_random_int(void)
{
	unsigned int r;
	get_random_bytes(&r, sizeof(r));

	return r;
}
EXPORT_SYMBOL_GPL(get_random_int);

#ifdef CONFIG_TTY
/**
 * tty_port_tty_wakeup - helper to wake up a tty
 *
 * @port: tty port
 */
void tty_port_tty_wakeup(struct tty_port *port)
{
	struct tty_struct *tty = tty_port_tty_get(port);

	if (tty) {
		tty_wakeup(tty);
		tty_kref_put(tty);
	}
}
EXPORT_SYMBOL_GPL(tty_port_tty_wakeup);

/**
 * tty_port_tty_hangup - helper to hang up a tty
 *
 * @port: tty port
 * @check_clocal: hang only ttys with CLOCAL unset?
 */
void tty_port_tty_hangup(struct tty_port *port, bool check_clocal)
{
	struct tty_struct *tty = tty_port_tty_get(port);

	if (tty && (!check_clocal || !C_CLOCAL(tty)))
		tty_hangup(tty);
	tty_kref_put(tty);
}
EXPORT_SYMBOL_GPL(tty_port_tty_hangup);
#endif /* CONFIG_TTY */

#ifdef CONFIG_PCI_IOV
/*
 * pci_vfs_assigned - returns number of VFs are assigned to a guest
 * @dev: the PCI device
 *
 * Returns number of VFs belonging to this device that are assigned to a guest.
 * If device is not a physical function returns -ENODEV.
 */
int pci_vfs_assigned(struct pci_dev *dev)
{
	struct pci_dev *vfdev;
	unsigned int vfs_assigned = 0;
	unsigned short dev_id;

	/* only search if we are a PF */
	if (!dev->is_physfn)
		return 0;

	/*
	 * determine the device ID for the VFs, the vendor ID will be the
	 * same as the PF so there is no need to check for that one
	 */
	pci_read_config_word(dev, dev->sriov->pos + PCI_SRIOV_VF_DID, &dev_id);

	/* loop through all the VFs to see if we own any that are assigned */
	vfdev = pci_get_device(dev->vendor, dev_id, NULL);
	while (vfdev) {
		/*
		 * It is considered assigned if it is a virtual function with
		 * our dev as the physical function and the assigned bit is set
		 */
		if (vfdev->is_virtfn && (vfdev->physfn == dev) &&
		    (vfdev->dev_flags & PCI_DEV_FLAGS_ASSIGNED))
			vfs_assigned++;

		vfdev = pci_get_device(dev->vendor, dev_id, vfdev);
	}

	return vfs_assigned;
}
EXPORT_SYMBOL_GPL(pci_vfs_assigned);
#endif /* CONFIG_PCI_IOV */

#ifdef CONFIG_OF
/**
 * of_find_property_value_of_size
 *
 * @np:		device node from which the property value is to be read.
 * @propname:	name of the property to be searched.
 * @len:	requested length of property value
 *
 * Search for a property in a device node and valid the requested size.
 * Returns the property value on success, -EINVAL if the property does not
 *  exist, -ENODATA if property does not have a value, and -EOVERFLOW if the
 * property data isn't large enough.
 *
 */
void *of_find_property_value_of_size(const struct device_node *np,
				     const char *propname, u32 len)
{
	struct property *prop = of_find_property(np, propname, NULL);

	if (!prop)
		return ERR_PTR(-EINVAL);
	if (!prop->value)
		return ERR_PTR(-ENODATA);
	if (len > prop->length)
		return ERR_PTR(-EOVERFLOW);

	return prop->value;
}

/**
 * of_property_read_u32_index - Find and read a u32 from a multi-value property.
 *
 * @np:		device node from which the property value is to be read.
 * @propname:	name of the property to be searched.
 * @index:	index of the u32 in the list of values
 * @out_value:	pointer to return value, modified only if no error.
 *
 * Search for a property in a device node and read nth 32-bit value from
 * it. Returns 0 on success, -EINVAL if the property does not exist,
 * -ENODATA if property does not have a value, and -EOVERFLOW if the
 * property data isn't large enough.
 *
 * The out_value is modified only if a valid u32 value can be decoded.
 */
int of_property_read_u32_index(const struct device_node *np,
				       const char *propname,
				       u32 index, u32 *out_value)
{
	const u32 *val = of_find_property_value_of_size(np, propname,
					((index + 1) * sizeof(*out_value)));

	if (IS_ERR(val))
		return PTR_ERR(val);

	*out_value = be32_to_cpup(((__be32 *)val) + index);
	return 0;
}
EXPORT_SYMBOL_GPL(of_property_read_u32_index);
#endif /* CONFIG_OF */

static inline void set_page_count(struct page *page, int v)
{
	atomic_set(&page->_count, v);
}

/*
 * Turn a non-refcounted page (->_count == 0) into refcounted with
 * a count of one.
 */
static inline void set_page_refcounted(struct page *page)
{
	VM_BUG_ON(PageTail(page));
	VM_BUG_ON(atomic_read(&page->_count));
	set_page_count(page, 1);
}

/*
 * split_page takes a non-compound higher-order page, and splits it into
 * n (1<<order) sub-pages: page[0..n]
 * Each sub-page must be freed individually.
 *
 * Note: this is probably too low level an operation for use in drivers.
 * Please consult with lkml before using this in your driver.
 */
void split_page(struct page *page, unsigned int order)
{
	int i;

	VM_BUG_ON(PageCompound(page));
	VM_BUG_ON(!page_count(page));

#ifdef CONFIG_KMEMCHECK
	/*
	 * Split shadow pages too, because free(page[0]) would
	 * otherwise free the whole shadow.
	 */
	if (kmemcheck_page_is_tracked(page))
		split_page(virt_to_page(page[0].shadow), order);
#endif

	for (i = 1; i < (1 << order); i++)
		set_page_refcounted(page + i);
}
EXPORT_SYMBOL_GPL(split_page);