/*
   * PCI Backend - Functions for creating a virtual configuration space for
   *               exported PCI Devices.
   *               It's dangerous to allow PCI Driver Domains to change their
   *               device's resources (memory, i/o ports, interrupts). We need to
   *               restrict changes to certain PCI Configuration registers:
   *               BARs, INTERRUPT_PIN, most registers in the header...
   *
   * Author: Ryan Wilson <hap9@epoch.ncsc.mil>
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/pci.h>
  #include "pciback.h"
  #include "conf_space.h"
  #include "conf_space_quirks.h"
  
  bool xen_pcibk_permissive;
  module_param_named(permissive, xen_pcibk_permissive, bool, 0644);
  
  /* This is where xen_pcibk_read_config_byte, xen_pcibk_read_config_word,
   * xen_pcibk_write_config_word, and xen_pcibk_write_config_byte are created. */
  #define DEFINE_PCI_CONFIG(op, size, type)			\
  int xen_pcibk_##op##_config_##size				\
  (struct pci_dev *dev, int offset, type value, void *data)	\
  {								\
  	return pci_##op##_config_##size(dev, offset, value);	\
  }
  
  DEFINE_PCI_CONFIG(read, byte, u8 *)
  DEFINE_PCI_CONFIG(read, word, u16 *)
  DEFINE_PCI_CONFIG(read, dword, u32 *)
  
  DEFINE_PCI_CONFIG(write, byte, u8)
  DEFINE_PCI_CONFIG(write, word, u16)
  DEFINE_PCI_CONFIG(write, dword, u32)
  
  static int conf_space_read(struct pci_dev *dev,
  			   const struct config_field_entry *entry,
  			   int offset, u32 *value)
  {
  	int ret = 0;
  	const struct config_field *field = entry->field;
  
  	*value = 0;
  
  	switch (field->size) {
  	case 1:
  		if (field->u.b.read)
  			ret = field->u.b.read(dev, offset, (u8 *) value,
  					      entry->data);
  		break;
  	case 2:
  		if (field->u.w.read)
  			ret = field->u.w.read(dev, offset, (u16 *) value,
  					      entry->data);
  		break;
  	case 4:
  		if (field->u.dw.read)
  			ret = field->u.dw.read(dev, offset, value, entry->data);
  		break;
  	}
  	return ret;
  }
  
  static int conf_space_write(struct pci_dev *dev,
  			    const struct config_field_entry *entry,
  			    int offset, u32 value)
  {
  	int ret = 0;
  	const struct config_field *field = entry->field;
  
  	switch (field->size) {
  	case 1:
  		if (field->u.b.write)
  			ret = field->u.b.write(dev, offset, (u8) value,
  					       entry->data);
  		break;
  	case 2:
  		if (field->u.w.write)
  			ret = field->u.w.write(dev, offset, (u16) value,
  					       entry->data);
  		break;
  	case 4:
  		if (field->u.dw.write)
  			ret = field->u.dw.write(dev, offset, value,
  						entry->data);
  		break;
  	}
  	return ret;
  }
  
  static inline u32 get_mask(int size)
  {
  	if (size == 1)
  		return 0xff;
  	else if (size == 2)
  		return 0xffff;
  	else
  		return 0xffffffff;
  }
  
  static inline int valid_request(int offset, int size)
  {
  	/* Validate request (no un-aligned requests) */
  	if ((size == 1 || size == 2 || size == 4) && (offset % size) == 0)
  		return 1;
  	return 0;
  }
  
  static inline u32 merge_value(u32 val, u32 new_val, u32 new_val_mask,
  			      int offset)
  {
  	if (offset >= 0) {
  		new_val_mask <<= (offset * 8);
  		new_val <<= (offset * 8);
  	} else {
  		new_val_mask >>= (offset * -8);
  		new_val >>= (offset * -8);
  	}
  	val = (val & ~new_val_mask) | (new_val & new_val_mask);
  
  	return val;
  }
  
  static int xen_pcibios_err_to_errno(int err)
  {
  	switch (err) {
  	case PCIBIOS_SUCCESSFUL:
  		return XEN_PCI_ERR_success;
  	case PCIBIOS_DEVICE_NOT_FOUND:
  		return XEN_PCI_ERR_dev_not_found;
  	case PCIBIOS_BAD_REGISTER_NUMBER:
  		return XEN_PCI_ERR_invalid_offset;
  	case PCIBIOS_FUNC_NOT_SUPPORTED:
  		return XEN_PCI_ERR_not_implemented;
  	case PCIBIOS_SET_FAILED:
  		return XEN_PCI_ERR_access_denied;
  	}
  	return err;
  }
  
  int xen_pcibk_config_read(struct pci_dev *dev, int offset, int size,
  			  u32 *ret_val)
  {
  	int err = 0;
  	struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
  	const struct config_field_entry *cfg_entry;
  	const struct config_field *field;
  	int req_start, req_end, field_start, field_end;
  	/* if read fails for any reason, return 0
  	 * (as if device didn't respond) */
  	u32 value = 0, tmp_val;
  
  	if (unlikely(verbose_request))
  		printk(KERN_DEBUG DRV_NAME ": %s: read %d bytes at 0x%x
  ",
  		       pci_name(dev), size, offset);
  
  	if (!valid_request(offset, size)) {
  		err = XEN_PCI_ERR_invalid_offset;
  		goto out;
  	}
  
  	/* Get the real value first, then modify as appropriate */
  	switch (size) {
  	case 1:
  		err = pci_read_config_byte(dev, offset, (u8 *) &value);
  		break;
  	case 2:
  		err = pci_read_config_word(dev, offset, (u16 *) &value);
  		break;
  	case 4:
  		err = pci_read_config_dword(dev, offset, &value);
  		break;
  	}
  
  	list_for_each_entry(cfg_entry, &dev_data->config_fields, list) {
  		field = cfg_entry->field;
  
  		req_start = offset;
  		req_end = offset + size;
  		field_start = OFFSET(cfg_entry);
  		field_end = OFFSET(cfg_entry) + field->size;
  
  		 if (req_end > field_start && field_end > req_start) {
  			err = conf_space_read(dev, cfg_entry, field_start,
  					      &tmp_val);
  			if (err)
  				goto out;
  
  			value = merge_value(value, tmp_val,
  					    get_mask(field->size),
  					    field_start - req_start);
  		}
  	}
  
  out:
  	if (unlikely(verbose_request))
  		printk(KERN_DEBUG DRV_NAME ": %s: read %d bytes at 0x%x = %x
  ",
  		       pci_name(dev), size, offset, value);
  
  	*ret_val = value;
  	return xen_pcibios_err_to_errno(err);
  }
  
  int xen_pcibk_config_write(struct pci_dev *dev, int offset, int size, u32 value)
  {
  	int err = 0, handled = 0;
  	struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
  	const struct config_field_entry *cfg_entry;
  	const struct config_field *field;
  	u32 tmp_val;
  	int req_start, req_end, field_start, field_end;
  
  	if (unlikely(verbose_request))
  		printk(KERN_DEBUG
  		       DRV_NAME ": %s: write request %d bytes at 0x%x = %x
  ",
  		       pci_name(dev), size, offset, value);
  
  	if (!valid_request(offset, size))
  		return XEN_PCI_ERR_invalid_offset;
  
  	list_for_each_entry(cfg_entry, &dev_data->config_fields, list) {
  		field = cfg_entry->field;
  
  		req_start = offset;
  		req_end = offset + size;
  		field_start = OFFSET(cfg_entry);
  		field_end = OFFSET(cfg_entry) + field->size;
  
  		 if (req_end > field_start && field_end > req_start) {
  			tmp_val = 0;
  
  			err = xen_pcibk_config_read(dev, field_start,
  						  field->size, &tmp_val);
  			if (err)
  				break;
  
  			tmp_val = merge_value(tmp_val, value, get_mask(size),
  					      req_start - field_start);
  
  			err = conf_space_write(dev, cfg_entry, field_start,
  					       tmp_val);
  
  			/* handled is set true here, but not every byte
  			 * may have been written! Properly detecting if
  			 * every byte is handled is unnecessary as the
  			 * flag is used to detect devices that need
  			 * special helpers to work correctly.
  			 */
  			handled = 1;
  		}
  	}
  
  	if (!handled && !err) {
  		/* By default, anything not specificially handled above is
  		 * read-only. The permissive flag changes this behavior so
  		 * that anything not specifically handled above is writable.
  		 * This means that some fields may still be read-only because
  		 * they have entries in the config_field list that intercept
  		 * the write and do nothing. */
  		if (dev_data->permissive || xen_pcibk_permissive) {
  			switch (size) {
  			case 1:
  				err = pci_write_config_byte(dev, offset,
  							    (u8) value);
  				break;
  			case 2:
  				err = pci_write_config_word(dev, offset,
  							    (u16) value);
  				break;
  			case 4:
  				err = pci_write_config_dword(dev, offset,
  							     (u32) value);
  				break;
  			}
  		} else if (!dev_data->warned_on_write) {
  			dev_data->warned_on_write = 1;
  			dev_warn(&dev->dev, "Driver tried to write to a "
  				 "read-only configuration space field at offset"
  				 " 0x%x, size %d. This may be harmless, but if "
  				 "you have problems with your device:
  "
  				 "1) see permissive attribute in sysfs
  "
  				 "2) report problems to the xen-devel "
  				 "mailing list along with details of your "
  				 "device obtained from lspci.
  ", offset, size);
  		}
  	}
  
  	return xen_pcibios_err_to_errno(err);
  }
  
  void xen_pcibk_config_free_dyn_fields(struct pci_dev *dev)
  {
  	struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
  	struct config_field_entry *cfg_entry, *t;
  	const struct config_field *field;
  
  	dev_dbg(&dev->dev, "free-ing dynamically allocated virtual "
  			   "configuration space fields
  ");
  	if (!dev_data)
  		return;
  
  	list_for_each_entry_safe(cfg_entry, t, &dev_data->config_fields, list) {
  		field = cfg_entry->field;
  
  		if (field->clean) {
  			field->clean((struct config_field *)field);
  
  			kfree(cfg_entry->data);
  
  			list_del(&cfg_entry->list);
  			kfree(cfg_entry);
  		}
  
  	}
  }
  
  void xen_pcibk_config_reset_dev(struct pci_dev *dev)
  {
  	struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
  	const struct config_field_entry *cfg_entry;
  	const struct config_field *field;
  
  	dev_dbg(&dev->dev, "resetting virtual configuration space
  ");
  	if (!dev_data)
  		return;
  
  	list_for_each_entry(cfg_entry, &dev_data->config_fields, list) {
  		field = cfg_entry->field;
  
  		if (field->reset)
  			field->reset(dev, OFFSET(cfg_entry), cfg_entry->data);
  	}
  }
  
  void xen_pcibk_config_free_dev(struct pci_dev *dev)
  {
  	struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
  	struct config_field_entry *cfg_entry, *t;
  	const struct config_field *field;
  
  	dev_dbg(&dev->dev, "free-ing virtual configuration space fields
  ");
  	if (!dev_data)
  		return;
  
  	list_for_each_entry_safe(cfg_entry, t, &dev_data->config_fields, list) {
  		list_del(&cfg_entry->list);
  
  		field = cfg_entry->field;
  
  		if (field->release)
  			field->release(dev, OFFSET(cfg_entry), cfg_entry->data);
  
  		kfree(cfg_entry);
  	}
  }
  
  int xen_pcibk_config_add_field_offset(struct pci_dev *dev,
  				    const struct config_field *field,
  				    unsigned int base_offset)
  {
  	int err = 0;
  	struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
  	struct config_field_entry *cfg_entry;
  	void *tmp;
  
  	cfg_entry = kmalloc(sizeof(*cfg_entry), GFP_KERNEL);
  	if (!cfg_entry) {
  		err = -ENOMEM;
  		goto out;
  	}
  
  	cfg_entry->data = NULL;
  	cfg_entry->field = field;
  	cfg_entry->base_offset = base_offset;
  
  	/* silently ignore duplicate fields */
  	err = xen_pcibk_field_is_dup(dev, OFFSET(cfg_entry));
  	if (err)
  		goto out;
  
  	if (field->init) {
  		tmp = field->init(dev, OFFSET(cfg_entry));
  
  		if (IS_ERR(tmp)) {
  			err = PTR_ERR(tmp);
  			goto out;
  		}
  
  		cfg_entry->data = tmp;
  	}
  
  	dev_dbg(&dev->dev, "added config field at offset 0x%02x
  ",
  		OFFSET(cfg_entry));
  	list_add_tail(&cfg_entry->list, &dev_data->config_fields);
  
  out:
  	if (err)
  		kfree(cfg_entry);
  
  	return err;
  }
  
  /* This sets up the device's virtual configuration space to keep track of
   * certain registers (like the base address registers (BARs) so that we can
   * keep the client from manipulating them directly.
   */
  int xen_pcibk_config_init_dev(struct pci_dev *dev)
  {
  	int err = 0;
  	struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
  
  	dev_dbg(&dev->dev, "initializing virtual configuration space
  ");
  
  	INIT_LIST_HEAD(&dev_data->config_fields);
  
  	err = xen_pcibk_config_header_add_fields(dev);
  	if (err)
  		goto out;
  
  	err = xen_pcibk_config_capability_add_fields(dev);
  	if (err)
  		goto out;
  
  	err = xen_pcibk_config_quirks_init(dev);
  
  out:
  	return err;
  }
  
  int xen_pcibk_config_init(void)
  {
  	return xen_pcibk_config_capability_init();
  }