drivers/iommu/of_iommu.c - third_party/linux - Git at Google

 /*
  * 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>

 #define NO_IOMMU	1

 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);

 static bool of_iommu_driver_present(struct device_node *np)
 {
 	/*
 	 * If the IOMMU still isn't ready by the time we reach init, assume
 	 * it never will be. We don't want to defer indefinitely, nor attempt
 	 * to dereference __iommu_of_table after it's been freed.
 	 */
 	if (system_state >= SYSTEM_RUNNING)
 		return false;

 	return of_match_node(&__iommu_of_table, np);
 }

 static int of_iommu_xlate(struct device *dev,
 			  struct of_phandle_args *iommu_spec)
 {
 	const struct iommu_ops *ops;
 	struct fwnode_handle *fwnode = &iommu_spec->np->fwnode;
 	int err;

 	ops = iommu_ops_from_fwnode(fwnode);
 	if ((ops && !ops->of_xlate) ||
 	    !of_device_is_available(iommu_spec->np) ||
 	    (!ops && !of_iommu_driver_present(iommu_spec->np)))
 		return NO_IOMMU;

 	err = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops);
 	if (err)
 		return err;
 	/*
 	 * The otherwise-empty fwspec handily serves to indicate the specific
 	 * IOMMU device we're waiting for, which will be useful if we ever get
 	 * a proper probe-ordering dependency mechanism in future.
 	 */
 	if (!ops)
 		return -EPROBE_DEFER;

 	return ops->of_xlate(dev, iommu_spec);
 }

 struct of_pci_iommu_alias_info {
 	struct device *dev;
 	struct device_node *np;
 };

 static int of_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data)
 {
 	struct of_pci_iommu_alias_info *info = data;
 	struct of_phandle_args iommu_spec = { .args_count = 1 };
 	int err;

 	err = of_pci_map_rid(info->np, alias, "iommu-map",
 			     "iommu-map-mask", &iommu_spec.np,
 			     iommu_spec.args);
 	if (err)
 		return err == -ENODEV ? NO_IOMMU : err;

 	err = of_iommu_xlate(info->dev, &iommu_spec);
 	of_node_put(iommu_spec.np);
 	return err;
 }

 const struct iommu_ops *of_iommu_configure(struct device *dev,
 					   struct device_node *master_np)
 {
 	const struct iommu_ops *ops = NULL;
 	struct iommu_fwspec *fwspec = dev->iommu_fwspec;
 	int err = NO_IOMMU;

 	if (!master_np)
 		return NULL;

 	if (fwspec) {
 		if (fwspec->ops)
 			return fwspec->ops;

 		/* In the deferred case, start again from scratch */
 		iommu_fwspec_free(dev);
 	}

 	/*
 	 * We don't currently walk up the tree looking for a parent IOMMU.
 	 * See the `Notes:' section of
 	 * Documentation/devicetree/bindings/iommu/iommu.txt
 	 */
 	if (dev_is_pci(dev)) {
 		struct of_pci_iommu_alias_info info = {
 			.dev = dev,
 			.np = master_np,
 		};

 		err = pci_for_each_dma_alias(to_pci_dev(dev),
 					     of_pci_iommu_init, &info);
 	} else {
 		struct of_phandle_args iommu_spec;
 		int idx = 0;

 		while (!of_parse_phandle_with_args(master_np, "iommus",
 						   "#iommu-cells",
 						   idx, &iommu_spec)) {
 			err = of_iommu_xlate(dev, &iommu_spec);
 			of_node_put(iommu_spec.np);
 			idx++;
 			if (err)
 				break;
 		}
 	}

 	/*
 	 * Two success conditions can be represented by non-negative err here:
 	 * >0 : there is no IOMMU, or one was unavailable for non-fatal reasons
 	 *  0 : we found an IOMMU, and dev->fwspec is initialised appropriately
 	 * <0 : any actual error
 	 */
 	if (!err)
 		ops = dev->iommu_fwspec->ops;
 	/*
 	 * If we have reason to believe the IOMMU driver missed the initial
 	 * add_device callback for dev, replay it to get things in order.
 	 */
 	if (ops && ops->add_device && dev->bus && !dev->iommu_group)
 		err = ops->add_device(dev);

 	/* Ignore all other errors apart from EPROBE_DEFER */
 	if (err == -EPROBE_DEFER) {
 		ops = ERR_PTR(err);
 	} else if (err < 0) {
 		dev_dbg(dev, "Adding to IOMMU failed: %d\n", err);
 		ops = NULL;
 	}

 	return ops;
 }
	/*
	* 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>

	#define NO_IOMMU 1

	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);

	static bool of_iommu_driver_present(struct device_node *np)
	{
	/*
	* If the IOMMU still isn't ready by the time we reach init, assume
	* it never will be. We don't want to defer indefinitely, nor attempt
	* to dereference __iommu_of_table after it's been freed.
	*/
	if (system_state >= SYSTEM_RUNNING)
	return false;

	return of_match_node(&__iommu_of_table, np);
	}

	static int of_iommu_xlate(struct device *dev,
	struct of_phandle_args *iommu_spec)
	{
	const struct iommu_ops *ops;
	struct fwnode_handle *fwnode = &iommu_spec->np->fwnode;
	int err;

	ops = iommu_ops_from_fwnode(fwnode);
	if ((ops && !ops->of_xlate) \|\|
	!of_device_is_available(iommu_spec->np) \|\|
	(!ops && !of_iommu_driver_present(iommu_spec->np)))
	return NO_IOMMU;

	err = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops);
	if (err)
	return err;
	/*
	* The otherwise-empty fwspec handily serves to indicate the specific
	* IOMMU device we're waiting for, which will be useful if we ever get
	* a proper probe-ordering dependency mechanism in future.
	*/
	if (!ops)
	return -EPROBE_DEFER;

	return ops->of_xlate(dev, iommu_spec);
	}

	struct of_pci_iommu_alias_info {
	struct device *dev;
	struct device_node *np;
	};

	static int of_pci_iommu_init(struct pci_dev pdev, u16 alias, void data)
	{
	struct of_pci_iommu_alias_info *info = data;
	struct of_phandle_args iommu_spec = { .args_count = 1 };
	int err;

	err = of_pci_map_rid(info->np, alias, "iommu-map",
	"iommu-map-mask", &iommu_spec.np,
	iommu_spec.args);
	if (err)
	return err == -ENODEV ? NO_IOMMU : err;

	err = of_iommu_xlate(info->dev, &iommu_spec);
	of_node_put(iommu_spec.np);
	return err;
	}

	const struct iommu_ops of_iommu_configure(struct device dev,
	struct device_node *master_np)
	{
	const struct iommu_ops *ops = NULL;
	struct iommu_fwspec *fwspec = dev->iommu_fwspec;
	int err = NO_IOMMU;

	if (!master_np)
	return NULL;

	if (fwspec) {
	if (fwspec->ops)
	return fwspec->ops;

	/* In the deferred case, start again from scratch */
	iommu_fwspec_free(dev);
	}

	/*
	* We don't currently walk up the tree looking for a parent IOMMU.
	* See the `Notes:' section of
	* Documentation/devicetree/bindings/iommu/iommu.txt
	*/
	if (dev_is_pci(dev)) {
	struct of_pci_iommu_alias_info info = {
	.dev = dev,
	.np = master_np,
	};

	err = pci_for_each_dma_alias(to_pci_dev(dev),
	of_pci_iommu_init, &info);
	} else {
	struct of_phandle_args iommu_spec;
	int idx = 0;

	while (!of_parse_phandle_with_args(master_np, "iommus",
	"#iommu-cells",
	idx, &iommu_spec)) {
	err = of_iommu_xlate(dev, &iommu_spec);
	of_node_put(iommu_spec.np);
	idx++;
	if (err)
	break;
	}
	}

	/*
	* Two success conditions can be represented by non-negative err here:
	* >0 : there is no IOMMU, or one was unavailable for non-fatal reasons
	* 0 : we found an IOMMU, and dev->fwspec is initialised appropriately
	* <0 : any actual error
	*/
	if (!err)
	ops = dev->iommu_fwspec->ops;
	/*
	* If we have reason to believe the IOMMU driver missed the initial
	* add_device callback for dev, replay it to get things in order.
	*/
	if (ops && ops->add_device && dev->bus && !dev->iommu_group)
	err = ops->add_device(dev);

	/* Ignore all other errors apart from EPROBE_DEFER */
	if (err == -EPROBE_DEFER) {
	ops = ERR_PTR(err);
	} else if (err < 0) {
	dev_dbg(dev, "Adding to IOMMU failed: %d\n", err);
	ops = NULL;
	}

	return ops;
	}