/*
 * 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
 *
 * Returns 1 on success, 0 when no information is available, or appropriate
 * errno value on error.
 *
 * In order to match a device from DSDT table to the corresponding CSRT device
 * we use MMIO address and IRQ.
 */
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_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)\n",
                (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\n",
                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\n");
                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\n");
                        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
 *
 * Returns 0 on success or appropriate errno value on error.
 *
 * Allocated memory should be freed with appropriate acpi_dma_controller_free()
 * call.
 */
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.
 */
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.
 */
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
 *
 * Returns 0, if no information is avaiable, -1 on mismatch, and 1 otherwise.
 *
 * 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.
 */
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
 *
 * Returns 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.
 *
 * Returns 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. Returns
 * 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);