/*
   * ACPI helpers for DMA request / controller
   *
   * Based on of-dma.c
   *
   * Copyright (C) 2013, Intel Corporation
   * Authors: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
   *	    Mika Westerberg <mika.westerberg@linux.intel.com>
   *
   * 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/device.h>
  #include <linux/module.h>
  #include <linux/list.h>
  #include <linux/mutex.h>
  #include <linux/slab.h>
  #include <linux/ioport.h>
  #include <linux/acpi.h>
  #include <linux/acpi_dma.h>
  
  static LIST_HEAD(acpi_dma_list);
  static DEFINE_MUTEX(acpi_dma_lock);
  
  /**
   * acpi_dma_parse_resource_group - match device and parse resource group
   * @grp:	CSRT resource group
   * @adev:	ACPI device to match with
   * @adma:	struct acpi_dma of the given DMA controller
   *
   * In order to match a device from DSDT table to the corresponding CSRT device
   * we use MMIO address and IRQ.
   *
   * Return:
   * 1 on success, 0 when no information is available, or appropriate errno value
   * on error.
   */
  static int acpi_dma_parse_resource_group(const struct acpi_csrt_group *grp,
  		struct acpi_device *adev, struct acpi_dma *adma)
  {
  	const struct acpi_csrt_shared_info *si;
  	struct list_head resource_list;
  	struct resource_list_entry *rentry;
  	resource_size_t mem = 0, irq = 0;
  	int ret;
  
  	if (grp->shared_info_length != sizeof(struct acpi_csrt_shared_info))
  		return -ENODEV;
  
  	INIT_LIST_HEAD(&resource_list);
  	ret = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);
  	if (ret <= 0)
  		return 0;
  
  	list_for_each_entry(rentry, &resource_list, node) {
  		if (resource_type(&rentry->res) == IORESOURCE_MEM)
  			mem = rentry->res.start;
  		else if (resource_type(&rentry->res) == IORESOURCE_IRQ)
  			irq = rentry->res.start;
  	}
  
  	acpi_dev_free_resource_list(&resource_list);
  
  	/* Consider initial zero values as resource not found */
  	if (mem == 0 && irq == 0)
  		return 0;
  
  	si = (const struct acpi_csrt_shared_info *)&grp[1];
  
  	/* Match device by MMIO and IRQ */
  	if (si->mmio_base_low != mem || si->gsi_interrupt != irq)
  		return 0;
  
  	dev_dbg(&adev->dev, "matches with %.4s%04X (rev %u)
  ",
  		(char *)&grp->vendor_id, grp->device_id, grp->revision);
  
  	/* Check if the request line range is available */
  	if (si->base_request_line == 0 && si->num_handshake_signals == 0)
  		return 0;
  
  	adma->base_request_line = si->base_request_line;
  	adma->end_request_line = si->base_request_line +
  				 si->num_handshake_signals - 1;
  
  	dev_dbg(&adev->dev, "request line base: 0x%04x end: 0x%04x
  ",
  		adma->base_request_line, adma->end_request_line);
  
  	return 1;
  }
  
  /**
   * acpi_dma_parse_csrt - parse CSRT to exctract additional DMA resources
   * @adev:	ACPI device to match with
   * @adma:	struct acpi_dma of the given DMA controller
   *
   * CSRT or Core System Resources Table is a proprietary ACPI table
   * introduced by Microsoft. This table can contain devices that are not in
   * the system DSDT table. In particular DMA controllers might be described
   * here.
   *
   * We are using this table to get the request line range of the specific DMA
   * controller to be used later.
   */
  static void acpi_dma_parse_csrt(struct acpi_device *adev, struct acpi_dma *adma)
  {
  	struct acpi_csrt_group *grp, *end;
  	struct acpi_table_csrt *csrt;
  	acpi_status status;
  	int ret;
  
  	status = acpi_get_table(ACPI_SIG_CSRT, 0,
  				(struct acpi_table_header **)&csrt);
  	if (ACPI_FAILURE(status)) {
  		if (status != AE_NOT_FOUND)
  			dev_warn(&adev->dev, "failed to get the CSRT table
  ");
  		return;
  	}
  
  	grp = (struct acpi_csrt_group *)(csrt + 1);
  	end = (struct acpi_csrt_group *)((void *)csrt + csrt->header.length);
  
  	while (grp < end) {
  		ret = acpi_dma_parse_resource_group(grp, adev, adma);
  		if (ret < 0) {
  			dev_warn(&adev->dev,
  				 "error in parsing resource group
  ");
  			return;
  		}
  
  		grp = (struct acpi_csrt_group *)((void *)grp + grp->length);
  	}
  }
  
  /**
   * acpi_dma_controller_register - Register a DMA controller to ACPI DMA helpers
   * @dev:		struct device of DMA controller
   * @acpi_dma_xlate:	translation function which converts a dma specifier
   *			into a dma_chan structure
   * @data		pointer to controller specific data to be used by
   *			translation function
   *
   * Allocated memory should be freed with appropriate acpi_dma_controller_free()
   * call.
   *
   * Return:
   * 0 on success or appropriate errno value on error.
   */
  int acpi_dma_controller_register(struct device *dev,
  		struct dma_chan *(*acpi_dma_xlate)
  		(struct acpi_dma_spec *, struct acpi_dma *),
  		void *data)
  {
  	struct acpi_device *adev;
  	struct acpi_dma	*adma;
  
  	if (!dev || !acpi_dma_xlate)
  		return -EINVAL;
  
  	/* Check if the device was enumerated by ACPI */
  	if (!ACPI_HANDLE(dev))
  		return -EINVAL;
  
  	if (acpi_bus_get_device(ACPI_HANDLE(dev), &adev))
  		return -EINVAL;
  
  	adma = kzalloc(sizeof(*adma), GFP_KERNEL);
  	if (!adma)
  		return -ENOMEM;
  
  	adma->dev = dev;
  	adma->acpi_dma_xlate = acpi_dma_xlate;
  	adma->data = data;
  
  	acpi_dma_parse_csrt(adev, adma);
  
  	/* Now queue acpi_dma controller structure in list */
  	mutex_lock(&acpi_dma_lock);
  	list_add_tail(&adma->dma_controllers, &acpi_dma_list);
  	mutex_unlock(&acpi_dma_lock);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(acpi_dma_controller_register);
  
  /**
   * acpi_dma_controller_free - Remove a DMA controller from ACPI DMA helpers list
   * @dev:	struct device of DMA controller
   *
   * Memory allocated by acpi_dma_controller_register() is freed here.
   *
   * Return:
   * 0 on success or appropriate errno value on error.
   */
  int acpi_dma_controller_free(struct device *dev)
  {
  	struct acpi_dma *adma;
  
  	if (!dev)
  		return -EINVAL;
  
  	mutex_lock(&acpi_dma_lock);
  
  	list_for_each_entry(adma, &acpi_dma_list, dma_controllers)
  		if (adma->dev == dev) {
  			list_del(&adma->dma_controllers);
  			mutex_unlock(&acpi_dma_lock);
  			kfree(adma);
  			return 0;
  		}
  
  	mutex_unlock(&acpi_dma_lock);
  	return -ENODEV;
  }
  EXPORT_SYMBOL_GPL(acpi_dma_controller_free);
  
  static void devm_acpi_dma_release(struct device *dev, void *res)
  {
  	acpi_dma_controller_free(dev);
  }
  
  /**
   * devm_acpi_dma_controller_register - resource managed acpi_dma_controller_register()
   * @dev:		device that is registering this DMA controller
   * @acpi_dma_xlate:	translation function
   * @data		pointer to controller specific data
   *
   * Managed acpi_dma_controller_register(). DMA controller registered by this
   * function are automatically freed on driver detach. See
   * acpi_dma_controller_register() for more information.
   *
   * Return:
   * 0 on success or appropriate errno value on error.
   */
  int devm_acpi_dma_controller_register(struct device *dev,
  		struct dma_chan *(*acpi_dma_xlate)
  		(struct acpi_dma_spec *, struct acpi_dma *),
  		void *data)
  {
  	void *res;
  	int ret;
  
  	res = devres_alloc(devm_acpi_dma_release, 0, GFP_KERNEL);
  	if (!res)
  		return -ENOMEM;
  
  	ret = acpi_dma_controller_register(dev, acpi_dma_xlate, data);
  	if (ret) {
  		devres_free(res);
  		return ret;
  	}
  	devres_add(dev, res);
  	return 0;
  }
  EXPORT_SYMBOL_GPL(devm_acpi_dma_controller_register);
  
  /**
   * devm_acpi_dma_controller_free - resource managed acpi_dma_controller_free()
   *
   * Unregister a DMA controller registered with
   * devm_acpi_dma_controller_register(). Normally this function will not need to
   * be called and the resource management code will ensure that the resource is
   * freed.
   */
  void devm_acpi_dma_controller_free(struct device *dev)
  {
  	WARN_ON(devres_destroy(dev, devm_acpi_dma_release, NULL, NULL));
  }
  EXPORT_SYMBOL_GPL(devm_acpi_dma_controller_free);
  
  /**
   * acpi_dma_update_dma_spec - prepare dma specifier to pass to translation function
   * @adma:	struct acpi_dma of DMA controller
   * @dma_spec:	dma specifier to update
   *
   * Accordingly to ACPI 5.0 Specification Table 6-170 "Fixed DMA Resource
   * Descriptor":
   *	DMA Request Line bits is a platform-relative number uniquely
   *	identifying the request line assigned. Request line-to-Controller
   *	mapping is done in a controller-specific OS driver.
   * That's why we can safely adjust slave_id when the appropriate controller is
   * found.
   *
   * Return:
   * 0, if no information is avaiable, -1 on mismatch, and 1 otherwise.
   */
  static int acpi_dma_update_dma_spec(struct acpi_dma *adma,
  		struct acpi_dma_spec *dma_spec)
  {
  	/* Set link to the DMA controller device */
  	dma_spec->dev = adma->dev;
  
  	/* Check if the request line range is available */
  	if (adma->base_request_line == 0 && adma->end_request_line == 0)
  		return 0;
  
  	/* Check if slave_id falls to the range */
  	if (dma_spec->slave_id < adma->base_request_line ||
  	    dma_spec->slave_id > adma->end_request_line)
  		return -1;
  
  	/*
  	 * Here we adjust slave_id. It should be a relative number to the base
  	 * request line.
  	 */
  	dma_spec->slave_id -= adma->base_request_line;
  
  	return 1;
  }
  
  struct acpi_dma_parser_data {
  	struct acpi_dma_spec dma_spec;
  	size_t index;
  	size_t n;
  };
  
  /**
   * acpi_dma_parse_fixed_dma - Parse FixedDMA ACPI resources to a DMA specifier
   * @res:	struct acpi_resource to get FixedDMA resources from
   * @data:	pointer to a helper struct acpi_dma_parser_data
   */
  static int acpi_dma_parse_fixed_dma(struct acpi_resource *res, void *data)
  {
  	struct acpi_dma_parser_data *pdata = data;
  
  	if (res->type == ACPI_RESOURCE_TYPE_FIXED_DMA) {
  		struct acpi_resource_fixed_dma *dma = &res->data.fixed_dma;
  
  		if (pdata->n++ == pdata->index) {
  			pdata->dma_spec.chan_id = dma->channels;
  			pdata->dma_spec.slave_id = dma->request_lines;
  		}
  	}
  
  	/* Tell the ACPI core to skip this resource */
  	return 1;
  }
  
  /**
   * acpi_dma_request_slave_chan_by_index - Get the DMA slave channel
   * @dev:	struct device to get DMA request from
   * @index:	index of FixedDMA descriptor for @dev
   *
   * Return:
   * Pointer to appropriate dma channel on success or NULL on error.
   */
  struct dma_chan *acpi_dma_request_slave_chan_by_index(struct device *dev,
  		size_t index)
  {
  	struct acpi_dma_parser_data pdata;
  	struct acpi_dma_spec *dma_spec = &pdata.dma_spec;
  	struct list_head resource_list;
  	struct acpi_device *adev;
  	struct acpi_dma *adma;
  	struct dma_chan *chan = NULL;
  	int found;
  
  	/* Check if the device was enumerated by ACPI */
  	if (!dev || !ACPI_HANDLE(dev))
  		return NULL;
  
  	if (acpi_bus_get_device(ACPI_HANDLE(dev), &adev))
  		return NULL;
  
  	memset(&pdata, 0, sizeof(pdata));
  	pdata.index = index;
  
  	/* Initial values for the request line and channel */
  	dma_spec->chan_id = -1;
  	dma_spec->slave_id = -1;
  
  	INIT_LIST_HEAD(&resource_list);
  	acpi_dev_get_resources(adev, &resource_list,
  			acpi_dma_parse_fixed_dma, &pdata);
  	acpi_dev_free_resource_list(&resource_list);
  
  	if (dma_spec->slave_id < 0 || dma_spec->chan_id < 0)
  		return NULL;
  
  	mutex_lock(&acpi_dma_lock);
  
  	list_for_each_entry(adma, &acpi_dma_list, dma_controllers) {
  		/*
  		 * We are not going to call translation function if slave_id
  		 * doesn't fall to the request range.
  		 */
  		found = acpi_dma_update_dma_spec(adma, dma_spec);
  		if (found < 0)
  			continue;
  		chan = adma->acpi_dma_xlate(dma_spec, adma);
  		/*
  		 * Try to get a channel only from the DMA controller that
  		 * matches the slave_id. See acpi_dma_update_dma_spec()
  		 * description for the details.
  		 */
  		if (found > 0 || chan)
  			break;
  	}
  
  	mutex_unlock(&acpi_dma_lock);
  	return chan;
  }
  EXPORT_SYMBOL_GPL(acpi_dma_request_slave_chan_by_index);
  
  /**
   * acpi_dma_request_slave_chan_by_name - Get the DMA slave channel
   * @dev:	struct device to get DMA request from
   * @name:	represents corresponding FixedDMA descriptor for @dev
   *
   * In order to support both Device Tree and ACPI in a single driver we
   * translate the names "tx" and "rx" here based on the most common case where
   * the first FixedDMA descriptor is TX and second is RX.
   *
   * Return:
   * Pointer to appropriate dma channel on success or NULL on error.
   */
  struct dma_chan *acpi_dma_request_slave_chan_by_name(struct device *dev,
  		const char *name)
  {
  	size_t index;
  
  	if (!strcmp(name, "tx"))
  		index = 0;
  	else if (!strcmp(name, "rx"))
  		index = 1;
  	else
  		return NULL;
  
  	return acpi_dma_request_slave_chan_by_index(dev, index);
  }
  EXPORT_SYMBOL_GPL(acpi_dma_request_slave_chan_by_name);
  
  /**
   * acpi_dma_simple_xlate - Simple ACPI DMA engine translation helper
   * @dma_spec: pointer to ACPI DMA specifier
   * @adma: pointer to ACPI DMA controller data
   *
   * A simple translation function for ACPI based devices. Passes &struct
   * dma_spec to the DMA controller driver provided filter function.
   *
   * Return:
   * Pointer to the channel if found or %NULL otherwise.
   */
  struct dma_chan *acpi_dma_simple_xlate(struct acpi_dma_spec *dma_spec,
  		struct acpi_dma *adma)
  {
  	struct acpi_dma_filter_info *info = adma->data;
  
  	if (!info || !info->filter_fn)
  		return NULL;
  
  	return dma_request_channel(info->dma_cap, info->filter_fn, dma_spec);
  }
  EXPORT_SYMBOL_GPL(acpi_dma_simple_xlate);