/*
   * OF helpers for IOMMU
   *
   * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms and conditions of the GNU General Public License,
   * version 2, as published by the Free Software Foundation.
   *
   * This program is distributed in the hope 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.
   *
   * You should have received a copy of the GNU General Public License along with
   * this program; if not, write to the Free Software Foundation, Inc.,
   * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
   */
  
  #include <linux/export.h>

  #include <linux/iommu.h>

  #include <linux/limits.h>
  #include <linux/of.h>

  #include <linux/of_iommu.h>

  #include <linux/of_pci.h>

  #include <linux/slab.h>

  static const struct of_device_id __iommu_of_table_sentinel
  	__used __section(__iommu_of_table_end);

  /**
   * of_get_dma_window - Parse *dma-window property and returns 0 if found.
   *
   * @dn: device node
   * @prefix: prefix for property name if any
   * @index: index to start to parse
   * @busno: Returns busno if supported. Otherwise pass NULL
   * @addr: Returns address that DMA starts
   * @size: Returns the range that DMA can handle
   *
   * This supports different formats flexibly. "prefix" can be
   * configured if any. "busno" and "index" are optionally
   * specified. Set 0(or NULL) if not used.
   */
  int of_get_dma_window(struct device_node *dn, const char *prefix, int index,
  		      unsigned long *busno, dma_addr_t *addr, size_t *size)
  {
  	const __be32 *dma_window, *end;
  	int bytes, cur_index = 0;
  	char propname[NAME_MAX], addrname[NAME_MAX], sizename[NAME_MAX];
  
  	if (!dn || !addr || !size)
  		return -EINVAL;
  
  	if (!prefix)
  		prefix = "";
  
  	snprintf(propname, sizeof(propname), "%sdma-window", prefix);
  	snprintf(addrname, sizeof(addrname), "%s#dma-address-cells", prefix);
  	snprintf(sizename, sizeof(sizename), "%s#dma-size-cells", prefix);
  
  	dma_window = of_get_property(dn, propname, &bytes);
  	if (!dma_window)
  		return -ENODEV;
  	end = dma_window + bytes / sizeof(*dma_window);
  
  	while (dma_window < end) {
  		u32 cells;
  		const void *prop;
  
  		/* busno is one cell if supported */
  		if (busno)
  			*busno = be32_to_cpup(dma_window++);
  
  		prop = of_get_property(dn, addrname, NULL);
  		if (!prop)
  			prop = of_get_property(dn, "#address-cells", NULL);
  
  		cells = prop ? be32_to_cpup(prop) : of_n_addr_cells(dn);
  		if (!cells)
  			return -EINVAL;
  		*addr = of_read_number(dma_window, cells);
  		dma_window += cells;
  
  		prop = of_get_property(dn, sizename, NULL);
  		cells = prop ? be32_to_cpup(prop) : of_n_size_cells(dn);
  		if (!cells)
  			return -EINVAL;
  		*size = of_read_number(dma_window, cells);
  		dma_window += cells;
  
  		if (cur_index++ == index)
  			break;
  	}
  	return 0;
  }
  EXPORT_SYMBOL_GPL(of_get_dma_window);

  struct of_iommu_node {
  	struct list_head list;
  	struct device_node *np;

  	const struct iommu_ops *ops;

  };
  static LIST_HEAD(of_iommu_list);
  static DEFINE_SPINLOCK(of_iommu_lock);

  void of_iommu_set_ops(struct device_node *np, const struct iommu_ops *ops)

  {
  	struct of_iommu_node *iommu = kzalloc(sizeof(*iommu), GFP_KERNEL);
  
  	if (WARN_ON(!iommu))
  		return;

  	of_node_get(np);

  	INIT_LIST_HEAD(&iommu->list);
  	iommu->np = np;
  	iommu->ops = ops;
  	spin_lock(&of_iommu_lock);
  	list_add_tail(&iommu->list, &of_iommu_list);
  	spin_unlock(&of_iommu_lock);
  }

  const struct iommu_ops *of_iommu_get_ops(struct device_node *np)

  {
  	struct of_iommu_node *node;

  	const struct iommu_ops *ops = NULL;

  
  	spin_lock(&of_iommu_lock);
  	list_for_each_entry(node, &of_iommu_list, list)
  		if (node->np == np) {
  			ops = node->ops;
  			break;
  		}
  	spin_unlock(&of_iommu_lock);
  	return ops;
  }

  static int __get_pci_rid(struct pci_dev *pdev, u16 alias, void *data)
  {
  	struct of_phandle_args *iommu_spec = data;
  
  	iommu_spec->args[0] = alias;
  	return iommu_spec->np == pdev->bus->dev.of_node;
  }
  
  static const struct iommu_ops
  *of_pci_iommu_configure(struct pci_dev *pdev, struct device_node *bridge_np)
  {
  	const struct iommu_ops *ops;
  	struct of_phandle_args iommu_spec;
  
  	/*
  	 * Start by tracing the RID alias down the PCI topology as
  	 * far as the host bridge whose OF node we have...
  	 * (we're not even attempting to handle multi-alias devices yet)
  	 */
  	iommu_spec.args_count = 1;
  	iommu_spec.np = bridge_np;
  	pci_for_each_dma_alias(pdev, __get_pci_rid, &iommu_spec);
  	/*
  	 * ...then find out what that becomes once it escapes the PCI
  	 * bus into the system beyond, and which IOMMU it ends up at.
  	 */
  	iommu_spec.np = NULL;
  	if (of_pci_map_rid(bridge_np, iommu_spec.args[0], "iommu-map",
  			   "iommu-map-mask", &iommu_spec.np, iommu_spec.args))
  		return NULL;
  
  	ops = of_iommu_get_ops(iommu_spec.np);

  	if (!ops || !ops->of_xlate ||
  	    iommu_fwspec_init(&pdev->dev, &iommu_spec.np->fwnode, ops) ||
  	    ops->of_xlate(&pdev->dev, &iommu_spec))

  		ops = NULL;
  
  	of_node_put(iommu_spec.np);
  	return ops;
  }

  const struct iommu_ops *of_iommu_configure(struct device *dev,
  					   struct device_node *master_np)

  {
  	struct of_phandle_args iommu_spec;
  	struct device_node *np;

  	const struct iommu_ops *ops = NULL;

  	int idx = 0;

  	if (dev_is_pci(dev))

  		return of_pci_iommu_configure(to_pci_dev(dev), master_np);

  	/*
  	 * We don't currently walk up the tree looking for a parent IOMMU.
  	 * See the `Notes:' section of
  	 * Documentation/devicetree/bindings/iommu/iommu.txt
  	 */

  	while (!of_parse_phandle_with_args(master_np, "iommus",

  					   "#iommu-cells", idx,
  					   &iommu_spec)) {
  		np = iommu_spec.np;
  		ops = of_iommu_get_ops(np);

  		if (!ops || !ops->of_xlate ||
  		    iommu_fwspec_init(dev, &np->fwnode, ops) ||
  		    ops->of_xlate(dev, &iommu_spec))

  			goto err_put_node;
  
  		of_node_put(np);
  		idx++;
  	}
  
  	return ops;
  
  err_put_node:
  	of_node_put(np);
  	return NULL;
  }

  static int __init of_iommu_init(void)

  {
  	struct device_node *np;
  	const struct of_device_id *match, *matches = &__iommu_of_table;
  
  	for_each_matching_node_and_match(np, matches, &match) {
  		const of_iommu_init_fn init_fn = match->data;
  
  		if (init_fn(np))
  			pr_err("Failed to initialise IOMMU %s
  ",
  				of_node_full_name(np));
  	}

  
  	return 0;

  }

  postcore_initcall_sync(of_iommu_init);