/*
   * drivers/pci/ats.c
   *
   * Copyright (C) 2009 Intel Corporation, Yu Zhao <yu.zhao@intel.com>
   * Copyright (C) 2011 Advanced Micro Devices,
   *
   * PCI Express I/O Virtualization (IOV) support.
   *   Address Translation Service 1.0
   *   Page Request Interface added by Joerg Roedel <joerg.roedel@amd.com>
   *   PASID support added by Joerg Roedel <joerg.roedel@amd.com>
   */
  
  #include <linux/export.h>
  #include <linux/pci-ats.h>
  #include <linux/pci.h>
  #include <linux/slab.h>
  
  #include "pci.h"
  
  static int ats_alloc_one(struct pci_dev *dev, int ps)
  {
  	int pos;
  	u16 cap;
  	struct pci_ats *ats;
  
  	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ATS);
  	if (!pos)
  		return -ENODEV;
  
  	ats = kzalloc(sizeof(*ats), GFP_KERNEL);
  	if (!ats)
  		return -ENOMEM;
  
  	ats->pos = pos;
  	ats->stu = ps;
  	pci_read_config_word(dev, pos + PCI_ATS_CAP, &cap);
  	ats->qdep = PCI_ATS_CAP_QDEP(cap) ? PCI_ATS_CAP_QDEP(cap) :
  					    PCI_ATS_MAX_QDEP;
  	dev->ats = ats;
  
  	return 0;
  }
  
  static void ats_free_one(struct pci_dev *dev)
  {
  	kfree(dev->ats);
  	dev->ats = NULL;
  }
  
  /**
   * pci_enable_ats - enable the ATS capability
   * @dev: the PCI device
   * @ps: the IOMMU page shift
   *
   * Returns 0 on success, or negative on failure.
   */
  int pci_enable_ats(struct pci_dev *dev, int ps)
  {
  	int rc;
  	u16 ctrl;
  
  	BUG_ON(dev->ats && dev->ats->is_enabled);
  
  	if (ps < PCI_ATS_MIN_STU)
  		return -EINVAL;
  
  	if (dev->is_physfn || dev->is_virtfn) {
  		struct pci_dev *pdev = dev->is_physfn ? dev : dev->physfn;
  
  		mutex_lock(&pdev->sriov->lock);
  		if (pdev->ats)
  			rc = pdev->ats->stu == ps ? 0 : -EINVAL;
  		else
  			rc = ats_alloc_one(pdev, ps);
  
  		if (!rc)
  			pdev->ats->ref_cnt++;
  		mutex_unlock(&pdev->sriov->lock);
  		if (rc)
  			return rc;
  	}
  
  	if (!dev->is_physfn) {
  		rc = ats_alloc_one(dev, ps);
  		if (rc)
  			return rc;
  	}
  
  	ctrl = PCI_ATS_CTRL_ENABLE;
  	if (!dev->is_virtfn)
  		ctrl |= PCI_ATS_CTRL_STU(ps - PCI_ATS_MIN_STU);
  	pci_write_config_word(dev, dev->ats->pos + PCI_ATS_CTRL, ctrl);
  
  	dev->ats->is_enabled = 1;
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(pci_enable_ats);
  
  /**
   * pci_disable_ats - disable the ATS capability
   * @dev: the PCI device
   */
  void pci_disable_ats(struct pci_dev *dev)
  {
  	u16 ctrl;
  
  	BUG_ON(!dev->ats || !dev->ats->is_enabled);
  
  	pci_read_config_word(dev, dev->ats->pos + PCI_ATS_CTRL, &ctrl);
  	ctrl &= ~PCI_ATS_CTRL_ENABLE;
  	pci_write_config_word(dev, dev->ats->pos + PCI_ATS_CTRL, ctrl);
  
  	dev->ats->is_enabled = 0;
  
  	if (dev->is_physfn || dev->is_virtfn) {
  		struct pci_dev *pdev = dev->is_physfn ? dev : dev->physfn;
  
  		mutex_lock(&pdev->sriov->lock);
  		pdev->ats->ref_cnt--;
  		if (!pdev->ats->ref_cnt)
  			ats_free_one(pdev);
  		mutex_unlock(&pdev->sriov->lock);
  	}
  
  	if (!dev->is_physfn)
  		ats_free_one(dev);
  }
  EXPORT_SYMBOL_GPL(pci_disable_ats);
  
  void pci_restore_ats_state(struct pci_dev *dev)
  {
  	u16 ctrl;
  
  	if (!pci_ats_enabled(dev))
  		return;
  	if (!pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ATS))
  		BUG();
  
  	ctrl = PCI_ATS_CTRL_ENABLE;
  	if (!dev->is_virtfn)
  		ctrl |= PCI_ATS_CTRL_STU(dev->ats->stu - PCI_ATS_MIN_STU);
  
  	pci_write_config_word(dev, dev->ats->pos + PCI_ATS_CTRL, ctrl);
  }
  EXPORT_SYMBOL_GPL(pci_restore_ats_state);
  
  /**
   * pci_ats_queue_depth - query the ATS Invalidate Queue Depth
   * @dev: the PCI device
   *
   * Returns the queue depth on success, or negative on failure.
   *
   * The ATS spec uses 0 in the Invalidate Queue Depth field to
   * indicate that the function can accept 32 Invalidate Request.
   * But here we use the `real' values (i.e. 1~32) for the Queue
   * Depth; and 0 indicates the function shares the Queue with
   * other functions (doesn't exclusively own a Queue).
   */
  int pci_ats_queue_depth(struct pci_dev *dev)
  {
  	int pos;
  	u16 cap;
  
  	if (dev->is_virtfn)
  		return 0;
  
  	if (dev->ats)
  		return dev->ats->qdep;
  
  	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ATS);
  	if (!pos)
  		return -ENODEV;
  
  	pci_read_config_word(dev, pos + PCI_ATS_CAP, &cap);
  
  	return PCI_ATS_CAP_QDEP(cap) ? PCI_ATS_CAP_QDEP(cap) :
  				       PCI_ATS_MAX_QDEP;
  }
  EXPORT_SYMBOL_GPL(pci_ats_queue_depth);
  
  #ifdef CONFIG_PCI_PRI
  /**
   * pci_enable_pri - Enable PRI capability
   * @ pdev: PCI device structure
   *
   * Returns 0 on success, negative value on error
   */
  int pci_enable_pri(struct pci_dev *pdev, u32 reqs)
  {
  	u16 control, status;
  	u32 max_requests;
  	int pos;
  
  	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
  	if (!pos)
  		return -EINVAL;
  
  	pci_read_config_word(pdev, pos + PCI_PRI_CTRL, &control);
  	pci_read_config_word(pdev, pos + PCI_PRI_STATUS, &status);
  	if ((control & PCI_PRI_CTRL_ENABLE) ||
  	    !(status & PCI_PRI_STATUS_STOPPED))
  		return -EBUSY;
  
  	pci_read_config_dword(pdev, pos + PCI_PRI_MAX_REQ, &max_requests);
  	reqs = min(max_requests, reqs);
  	pci_write_config_dword(pdev, pos + PCI_PRI_ALLOC_REQ, reqs);
  
  	control |= PCI_PRI_CTRL_ENABLE;
  	pci_write_config_word(pdev, pos + PCI_PRI_CTRL, control);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(pci_enable_pri);
  
  /**
   * pci_disable_pri - Disable PRI capability
   * @pdev: PCI device structure
   *
   * Only clears the enabled-bit, regardless of its former value
   */
  void pci_disable_pri(struct pci_dev *pdev)
  {
  	u16 control;
  	int pos;
  
  	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
  	if (!pos)
  		return;
  
  	pci_read_config_word(pdev, pos + PCI_PRI_CTRL, &control);
  	control &= ~PCI_PRI_CTRL_ENABLE;
  	pci_write_config_word(pdev, pos + PCI_PRI_CTRL, control);
  }
  EXPORT_SYMBOL_GPL(pci_disable_pri);
  
  /**
   * pci_reset_pri - Resets device's PRI state
   * @pdev: PCI device structure
   *
   * The PRI capability must be disabled before this function is called.
   * Returns 0 on success, negative value on error.
   */
  int pci_reset_pri(struct pci_dev *pdev)
  {
  	u16 control;
  	int pos;
  
  	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
  	if (!pos)
  		return -EINVAL;
  
  	pci_read_config_word(pdev, pos + PCI_PRI_CTRL, &control);
  	if (control & PCI_PRI_CTRL_ENABLE)
  		return -EBUSY;
  
  	control |= PCI_PRI_CTRL_RESET;
  
  	pci_write_config_word(pdev, pos + PCI_PRI_CTRL, control);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(pci_reset_pri);
  #endif /* CONFIG_PCI_PRI */
  
  #ifdef CONFIG_PCI_PASID
  /**
   * pci_enable_pasid - Enable the PASID capability
   * @pdev: PCI device structure
   * @features: Features to enable
   *
   * Returns 0 on success, negative value on error. This function checks
   * whether the features are actually supported by the device and returns
   * an error if not.
   */
  int pci_enable_pasid(struct pci_dev *pdev, int features)
  {
  	u16 control, supported;
  	int pos;
  
  	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
  	if (!pos)
  		return -EINVAL;
  
  	pci_read_config_word(pdev, pos + PCI_PASID_CTRL, &control);
  	pci_read_config_word(pdev, pos + PCI_PASID_CAP, &supported);
  
  	if (control & PCI_PASID_CTRL_ENABLE)
  		return -EINVAL;
  
  	supported &= PCI_PASID_CAP_EXEC | PCI_PASID_CAP_PRIV;
  
  	/* User wants to enable anything unsupported? */
  	if ((supported & features) != features)
  		return -EINVAL;
  
  	control = PCI_PASID_CTRL_ENABLE | features;
  
  	pci_write_config_word(pdev, pos + PCI_PASID_CTRL, control);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(pci_enable_pasid);
  
  /**
   * pci_disable_pasid - Disable the PASID capability
   * @pdev: PCI device structure
   *
   */
  void pci_disable_pasid(struct pci_dev *pdev)
  {
  	u16 control = 0;
  	int pos;
  
  	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
  	if (!pos)
  		return;
  
  	pci_write_config_word(pdev, pos + PCI_PASID_CTRL, control);
  }
  EXPORT_SYMBOL_GPL(pci_disable_pasid);
  
  /**
   * pci_pasid_features - Check which PASID features are supported
   * @pdev: PCI device structure
   *
   * Returns a negative value when no PASI capability is present.
   * Otherwise is returns a bitmask with supported features. Current
   * features reported are:
   * PCI_PASID_CAP_EXEC - Execute permission supported
   * PCI_PASID_CAP_PRIV - Privileged mode supported
   */
  int pci_pasid_features(struct pci_dev *pdev)
  {
  	u16 supported;
  	int pos;
  
  	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
  	if (!pos)
  		return -EINVAL;
  
  	pci_read_config_word(pdev, pos + PCI_PASID_CAP, &supported);
  
  	supported &= PCI_PASID_CAP_EXEC | PCI_PASID_CAP_PRIV;
  
  	return supported;
  }
  EXPORT_SYMBOL_GPL(pci_pasid_features);
  
  #define PASID_NUMBER_SHIFT	8
  #define PASID_NUMBER_MASK	(0x1f << PASID_NUMBER_SHIFT)
  /**
   * pci_max_pasid - Get maximum number of PASIDs supported by device
   * @pdev: PCI device structure
   *
   * Returns negative value when PASID capability is not present.
   * Otherwise it returns the numer of supported PASIDs.
   */
  int pci_max_pasids(struct pci_dev *pdev)
  {
  	u16 supported;
  	int pos;
  
  	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
  	if (!pos)
  		return -EINVAL;
  
  	pci_read_config_word(pdev, pos + PCI_PASID_CAP, &supported);
  
  	supported = (supported & PASID_NUMBER_MASK) >> PASID_NUMBER_SHIFT;
  
  	return (1 << supported);
  }
  EXPORT_SYMBOL_GPL(pci_max_pasids);
  #endif /* CONFIG_PCI_PASID */