fpga: add device feature list support

Device Feature List (DFL) defines a feature list structure that creates
a linked list of feature headers within the MMIO space to provide an
extensible way of adding features. This patch introduces a kernel module
to provide basic infrastructure to support FPGA devices which implement
the Device Feature List.

Usually there will be different features and their sub features linked into
the DFL. This code provides common APIs for feature enumeration, it creates
a container device (FPGA base region), walks through the DFLs and creates
platform devices for feature devices (Currently it only supports two
different feature devices, FPGA Management Engine (FME) and Port which
the Accelerator Function Unit (AFU) connected to). In order to enumerate
the DFLs, the common APIs required low level driver to provide necessary
enumeration information (e.g. address for each device feature list for
given device) and fill it to the dfl_fpga_enum_info data structure. Please
refer to below description for APIs added for enumeration.

Functions for enumeration information preparation:
 *dfl_fpga_enum_info_alloc
   allocate enumeration information data structure.

 *dfl_fpga_enum_info_add_dfl
   add a device feature list to dfl_fpga_enum_info data structure.

 *dfl_fpga_enum_info_free
   free dfl_fpga_enum_info data structure and related resources.

Functions for feature device enumeration:
 *dfl_fpga_feature_devs_enumerate
   enumerate feature devices and return container device.

 *dfl_fpga_feature_devs_remove
   remove feature devices under given container device.

Signed-off-by: Tim Whisonant <tim.whisonant@intel.com>
Signed-off-by: Enno Luebbers <enno.luebbers@intel.com>
Signed-off-by: Shiva Rao <shiva.rao@intel.com>
Signed-off-by: Christopher Rauer <christopher.rauer@intel.com>
Signed-off-by: Zhang Yi <yi.z.zhang@intel.com>
Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Wu Hao <hao.wu@intel.com>
Acked-by: Alan Tull <atull@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

4 files changed, 1019 insertions, 0 deletions

diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
index ee9c5420c47f..4880fd676a19 100644
--- a/drivers/fpga/Kconfig
+++ b/drivers/fpga/Kconfig
@@ -130,4 +130,20 @@ config OF_FPGA_REGION
           Support for loading FPGA images by applying a Device Tree
           overlay.
 
+config FPGA_DFL
+        tristate "FPGA Device Feature List (DFL) support"
+        select FPGA_BRIDGE
+        select FPGA_REGION
+        help
+          Device Feature List (DFL) defines a feature list structure that
+          creates a linked list of feature headers within the MMIO space
+          to provide an extensible way of adding features for FPGA.
+          Driver can walk through the feature headers to enumerate feature
+          devices (e.g. FPGA Management Engine, Port and Accelerator
+          Function Unit) and their private features for target FPGA devices.
+
+          Select this option to enable common support for Field-Programmable
+          Gate Array (FPGA) solutions which implement Device Feature List.
+          It provides enumeration APIs and feature device infrastructure.
+
 endif # FPGA
diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
index f9803dad6919..7a7a11739e00 100644
--- a/drivers/fpga/Makefile
+++ b/drivers/fpga/Makefile
@@ -28,3 +28,6 @@ obj-$(CONFIG_XILINX_PR_DECOUPLER)	+= xilinx-pr-decoupler.o
 # High Level Interfaces
 obj-$(CONFIG_FPGA_REGION)               += fpga-region.o
 obj-$(CONFIG_OF_FPGA_REGION)            += of-fpga-region.o
+
+# FPGA Device Feature List Support
+obj-$(CONFIG_FPGA_DFL)                  += dfl.o
diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
new file mode 100644
index 000000000000..d1dff360ea14
--- /dev/null
+++ b/drivers/fpga/dfl.c
@@ -0,0 +1,721 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for FPGA Device Feature List (DFL) Support
+ *
+ * Copyright (C) 2017-2018 Intel Corporation, Inc.
+ *
+ * Authors:
+ *   Kang Luwei <luwei.kang@intel.com>
+ *   Zhang Yi <yi.z.zhang@intel.com>
+ *   Wu Hao <hao.wu@intel.com>
+ *   Xiao Guangrong <guangrong.xiao@linux.intel.com>
+ */
+#include <linux/module.h>
+
+#include "dfl.h"
+
+static DEFINE_MUTEX(dfl_id_mutex);
+
+/*
+ * when adding a new feature dev support in DFL framework, it's required to
+ * add a new item in enum dfl_id_type and provide related information in below
+ * dfl_devs table which is indexed by dfl_id_type, e.g. name string used for
+ * platform device creation (define name strings in dfl.h, as they could be
+ * reused by platform device drivers).
+ */
+enum dfl_id_type {
+        FME_ID,         /* fme id allocation and mapping */
+        PORT_ID,        /* port id allocation and mapping */
+        DFL_ID_MAX,
+};
+
+/**
+ * dfl_dev_info - dfl feature device information.
+ * @name: name string of the feature platform device.
+ * @dfh_id: id value in Device Feature Header (DFH) register by DFL spec.
+ * @id: idr id of the feature dev.
+ */
+struct dfl_dev_info {
+        const char *name;
+        u32 dfh_id;
+        struct idr id;
+};
+
+/* it is indexed by dfl_id_type */
+static struct dfl_dev_info dfl_devs[] = {
+        {.name = DFL_FPGA_FEATURE_DEV_FME, .dfh_id = DFH_ID_FIU_FME},
+        {.name = DFL_FPGA_FEATURE_DEV_PORT, .dfh_id = DFH_ID_FIU_PORT},
+};
+
+static void dfl_ids_init(void)
+{
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(dfl_devs); i++)
+                idr_init(&dfl_devs[i].id);
+}
+
+static void dfl_ids_destroy(void)
+{
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(dfl_devs); i++)
+                idr_destroy(&dfl_devs[i].id);
+}
+
+static int dfl_id_alloc(enum dfl_id_type type, struct device *dev)
+{
+        int id;
+
+        WARN_ON(type >= DFL_ID_MAX);
+        mutex_lock(&dfl_id_mutex);
+        id = idr_alloc(&dfl_devs[type].id, dev, 0, 0, GFP_KERNEL);
+        mutex_unlock(&dfl_id_mutex);
+
+        return id;
+}
+
+static void dfl_id_free(enum dfl_id_type type, int id)
+{
+        WARN_ON(type >= DFL_ID_MAX);
+        mutex_lock(&dfl_id_mutex);
+        idr_remove(&dfl_devs[type].id, id);
+        mutex_unlock(&dfl_id_mutex);
+}
+
+static enum dfl_id_type feature_dev_id_type(struct platform_device *pdev)
+{
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(dfl_devs); i++)
+                if (!strcmp(dfl_devs[i].name, pdev->name))
+                        return i;
+
+        return DFL_ID_MAX;
+}
+
+static enum dfl_id_type dfh_id_to_type(u32 id)
+{
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(dfl_devs); i++)
+                if (dfl_devs[i].dfh_id == id)
+                        return i;
+
+        return DFL_ID_MAX;
+}
+
+/**
+ * struct build_feature_devs_info - info collected during feature dev build.
+ *
+ * @dev: device to enumerate.
+ * @cdev: the container device for all feature devices.
+ * @feature_dev: current feature device.
+ * @ioaddr: header register region address of feature device in enumeration.
+ * @sub_features: a sub features linked list for feature device in enumeration.
+ * @feature_num: number of sub features for feature device in enumeration.
+ */
+struct build_feature_devs_info {
+        struct device *dev;
+        struct dfl_fpga_cdev *cdev;
+        struct platform_device *feature_dev;
+        void __iomem *ioaddr;
+        struct list_head sub_features;
+        int feature_num;
+};
+
+/**
+ * struct dfl_feature_info - sub feature info collected during feature dev build
+ *
+ * @fid: id of this sub feature.
+ * @mmio_res: mmio resource of this sub feature.
+ * @ioaddr: mapped base address of mmio resource.
+ * @node: node in sub_features linked list.
+ */
+struct dfl_feature_info {
+        u64 fid;
+        struct resource mmio_res;
+        void __iomem *ioaddr;
+        struct list_head node;
+};
+
+static void dfl_fpga_cdev_add_port_dev(struct dfl_fpga_cdev *cdev,
+                                       struct platform_device *port)
+{
+        struct dfl_feature_platform_data *pdata = dev_get_platdata(&port->dev);
+
+        mutex_lock(&cdev->lock);
+        list_add(&pdata->node, &cdev->port_dev_list);
+        get_device(&pdata->dev->dev);
+        mutex_unlock(&cdev->lock);
+}
+
+/*
+ * register current feature device, it is called when we need to switch to
+ * another feature parsing or we have parsed all features on given device
+ * feature list.
+ */
+static int build_info_commit_dev(struct build_feature_devs_info *binfo)
+{
+        struct platform_device *fdev = binfo->feature_dev;
+        struct dfl_feature_platform_data *pdata;
+        struct dfl_feature_info *finfo, *p;
+        int ret, index = 0;
+
+        if (!fdev)
+                return 0;
+
+        /*
+         * we do not need to care for the memory which is associated with
+         * the platform device. After calling platform_device_unregister(),
+         * it will be automatically freed by device's release() callback,
+         * platform_device_release().
+         */
+        pdata = kzalloc(dfl_feature_platform_data_size(binfo->feature_num),
+                        GFP_KERNEL);
+        if (!pdata)
+                return -ENOMEM;
+
+        pdata->dev = fdev;
+        pdata->num = binfo->feature_num;
+        pdata->dfl_cdev = binfo->cdev;
+        mutex_init(&pdata->lock);
+
+        /*
+         * the count should be initialized to 0 to make sure
+         *__fpga_port_enable() following __fpga_port_disable()
+         * works properly for port device.
+         * and it should always be 0 for fme device.
+         */
+        WARN_ON(pdata->disable_count);
+
+        fdev->dev.platform_data = pdata;
+
+        /* each sub feature has one MMIO resource */
+        fdev->num_resources = binfo->feature_num;
+        fdev->resource = kcalloc(binfo->feature_num, sizeof(*fdev->resource),
+                                 GFP_KERNEL);
+        if (!fdev->resource)
+                return -ENOMEM;
+
+        /* fill features and resource information for feature dev */
+        list_for_each_entry_safe(finfo, p, &binfo->sub_features, node) {
+                struct dfl_feature *feature = &pdata->features[index];
+
+                /* save resource information for each feature */
+                feature->id = finfo->fid;
+                feature->resource_index = index;
+                feature->ioaddr = finfo->ioaddr;
+                fdev->resource[index++] = finfo->mmio_res;
+
+                list_del(&finfo->node);
+                kfree(finfo);
+        }
+
+        ret = platform_device_add(binfo->feature_dev);
+        if (!ret) {
+                if (feature_dev_id_type(binfo->feature_dev) == PORT_ID)
+                        dfl_fpga_cdev_add_port_dev(binfo->cdev,
+                                                   binfo->feature_dev);
+                else
+                        binfo->cdev->fme_dev =
+                                        get_device(&binfo->feature_dev->dev);
+                /*
+                 * reset it to avoid build_info_free() freeing their resource.
+                 *
+                 * The resource of successfully registered feature devices
+                 * will be freed by platform_device_unregister(). See the
+                 * comments in build_info_create_dev().
+                 */
+                binfo->feature_dev = NULL;
+        }
+
+        return ret;
+}
+
+static int
+build_info_create_dev(struct build_feature_devs_info *binfo,
+                      enum dfl_id_type type, void __iomem *ioaddr)
+{
+        struct platform_device *fdev;
+        int ret;
+
+        if (type >= DFL_ID_MAX)
+                return -EINVAL;
+
+        /* we will create a new device, commit current device first */
+        ret = build_info_commit_dev(binfo);
+        if (ret)
+                return ret;
+
+        /*
+         * we use -ENODEV as the initialization indicator which indicates
+         * whether the id need to be reclaimed
+         */
+        fdev = platform_device_alloc(dfl_devs[type].name, -ENODEV);
+        if (!fdev)
+                return -ENOMEM;
+
+        binfo->feature_dev = fdev;
+        binfo->feature_num = 0;
+        binfo->ioaddr = ioaddr;
+        INIT_LIST_HEAD(&binfo->sub_features);
+
+        fdev->id = dfl_id_alloc(type, &fdev->dev);
+        if (fdev->id < 0)
+                return fdev->id;
+
+        fdev->dev.parent = &binfo->cdev->region->dev;
+
+        return 0;
+}
+
+static void build_info_free(struct build_feature_devs_info *binfo)
+{
+        struct dfl_feature_info *finfo, *p;
+
+        /*
+         * it is a valid id, free it. See comments in
+         * build_info_create_dev()
+         */
+        if (binfo->feature_dev && binfo->feature_dev->id >= 0) {
+                dfl_id_free(feature_dev_id_type(binfo->feature_dev),
+                            binfo->feature_dev->id);
+
+                list_for_each_entry_safe(finfo, p, &binfo->sub_features, node) {
+                        list_del(&finfo->node);
+                        kfree(finfo);
+                }
+        }
+
+        platform_device_put(binfo->feature_dev);
+
+        devm_kfree(binfo->dev, binfo);
+}
+
+static inline u32 feature_size(void __iomem *start)
+{
+        u64 v = readq(start + DFH);
+        u32 ofst = FIELD_GET(DFH_NEXT_HDR_OFST, v);
+        /* workaround for private features with invalid size, use 4K instead */
+        return ofst ? ofst : 4096;
+}
+
+static u64 feature_id(void __iomem *start)
+{
+        u64 v = readq(start + DFH);
+        u16 id = FIELD_GET(DFH_ID, v);
+        u8 type = FIELD_GET(DFH_TYPE, v);
+
+        if (type == DFH_TYPE_FIU)
+                return FEATURE_ID_FIU_HEADER;
+        else if (type == DFH_TYPE_PRIVATE)
+                return id;
+        else if (type == DFH_TYPE_AFU)
+                return FEATURE_ID_AFU;
+
+        WARN_ON(1);
+        return 0;
+}
+
+/*
+ * when create sub feature instances, for private features, it doesn't need
+ * to provide resource size and feature id as they could be read from DFH
+ * register. For afu sub feature, its register region only contains user
+ * defined registers, so never trust any information from it, just use the
+ * resource size information provided by its parent FIU.
+ */
+static int
+create_feature_instance(struct build_feature_devs_info *binfo,
+                        struct dfl_fpga_enum_dfl *dfl, resource_size_t ofst,
+                        resource_size_t size, u64 fid)
+{
+        struct dfl_feature_info *finfo;
+
+        /* read feature size and id if inputs are invalid */
+        size = size ? size : feature_size(dfl->ioaddr + ofst);
+        fid = fid ? fid : feature_id(dfl->ioaddr + ofst);
+
+        if (dfl->len - ofst < size)
+                return -EINVAL;
+
+        finfo = kzalloc(sizeof(*finfo), GFP_KERNEL);
+        if (!finfo)
+                return -ENOMEM;
+
+        finfo->fid = fid;
+        finfo->mmio_res.start = dfl->start + ofst;
+        finfo->mmio_res.end = finfo->mmio_res.start + size - 1;
+        finfo->mmio_res.flags = IORESOURCE_MEM;
+        finfo->ioaddr = dfl->ioaddr + ofst;
+
+        list_add_tail(&finfo->node, &binfo->sub_features);
+        binfo->feature_num++;
+
+        return 0;
+}
+
+static int parse_feature_port_afu(struct build_feature_devs_info *binfo,
+                                  struct dfl_fpga_enum_dfl *dfl,
+                                  resource_size_t ofst)
+{
+        u64 v = readq(binfo->ioaddr + PORT_HDR_CAP);
+        u32 size = FIELD_GET(PORT_CAP_MMIO_SIZE, v) << 10;
+
+        WARN_ON(!size);
+
+        return create_feature_instance(binfo, dfl, ofst, size, FEATURE_ID_AFU);
+}
+
+static int parse_feature_afu(struct build_feature_devs_info *binfo,
+                             struct dfl_fpga_enum_dfl *dfl,
+                             resource_size_t ofst)
+{
+        if (!binfo->feature_dev) {
+                dev_err(binfo->dev, "this AFU does not belong to any FIU.\n");
+                return -EINVAL;
+        }
+
+        switch (feature_dev_id_type(binfo->feature_dev)) {
+        case PORT_ID:
+                return parse_feature_port_afu(binfo, dfl, ofst);
+        default:
+                dev_info(binfo->dev, "AFU belonging to FIU %s is not supported yet.\n",
+                         binfo->feature_dev->name);
+        }
+
+        return 0;
+}
+
+static int parse_feature_fiu(struct build_feature_devs_info *binfo,
+                             struct dfl_fpga_enum_dfl *dfl,
+                             resource_size_t ofst)
+{
+        u32 id, offset;
+        u64 v;
+        int ret = 0;
+
+        v = readq(dfl->ioaddr + ofst + DFH);
+        id = FIELD_GET(DFH_ID, v);
+
+        /* create platform device for dfl feature dev */
+        ret = build_info_create_dev(binfo, dfh_id_to_type(id),
+                                    dfl->ioaddr + ofst);
+        if (ret)
+                return ret;
+
+        ret = create_feature_instance(binfo, dfl, ofst, 0, 0);
+        if (ret)
+                return ret;
+        /*
+         * find and parse FIU's child AFU via its NEXT_AFU register.
+         * please note that only Port has valid NEXT_AFU pointer per spec.
+         */
+        v = readq(dfl->ioaddr + ofst + NEXT_AFU);
+
+        offset = FIELD_GET(NEXT_AFU_NEXT_DFH_OFST, v);
+        if (offset)
+                return parse_feature_afu(binfo, dfl, ofst + offset);
+
+        dev_dbg(binfo->dev, "No AFUs detected on FIU %d\n", id);
+
+        return ret;
+}
+
+static int parse_feature_private(struct build_feature_devs_info *binfo,
+                                 struct dfl_fpga_enum_dfl *dfl,
+                                 resource_size_t ofst)
+{
+        if (!binfo->feature_dev) {
+                dev_err(binfo->dev, "the private feature %llx does not belong to any AFU.\n",
+                        (unsigned long long)feature_id(dfl->ioaddr + ofst));
+                return -EINVAL;
+        }
+
+        return create_feature_instance(binfo, dfl, ofst, 0, 0);
+}
+
+/**
+ * parse_feature - parse a feature on given device feature list
+ *
+ * @binfo: build feature devices information.
+ * @dfl: device feature list to parse
+ * @ofst: offset to feature header on this device feature list
+ */
+static int parse_feature(struct build_feature_devs_info *binfo,
+                         struct dfl_fpga_enum_dfl *dfl, resource_size_t ofst)
+{
+        u64 v;
+        u32 type;
+
+        v = readq(dfl->ioaddr + ofst + DFH);
+        type = FIELD_GET(DFH_TYPE, v);
+
+        switch (type) {
+        case DFH_TYPE_AFU:
+                return parse_feature_afu(binfo, dfl, ofst);
+        case DFH_TYPE_PRIVATE:
+                return parse_feature_private(binfo, dfl, ofst);
+        case DFH_TYPE_FIU:
+                return parse_feature_fiu(binfo, dfl, ofst);
+        default:
+                dev_info(binfo->dev,
+                         "Feature Type %x is not supported.\n", type);
+        }
+
+        return 0;
+}
+
+static int parse_feature_list(struct build_feature_devs_info *binfo,
+                              struct dfl_fpga_enum_dfl *dfl)
+{
+        void __iomem *start = dfl->ioaddr;
+        void __iomem *end = dfl->ioaddr + dfl->len;
+        int ret = 0;
+        u32 ofst = 0;
+        u64 v;
+
+        /* walk through the device feature list via DFH's next DFH pointer. */
+        for (; start < end; start += ofst) {
+                if (end - start < DFH_SIZE) {
+                        dev_err(binfo->dev, "The region is too small to contain a feature.\n");
+                        return -EINVAL;
+                }
+
+                ret = parse_feature(binfo, dfl, start - dfl->ioaddr);
+                if (ret)
+                        return ret;
+
+                v = readq(start + DFH);
+                ofst = FIELD_GET(DFH_NEXT_HDR_OFST, v);
+
+                /* stop parsing if EOL(End of List) is set or offset is 0 */
+                if ((v & DFH_EOL) || !ofst)
+                        break;
+        }
+
+        /* commit current feature device when reach the end of list */
+        return build_info_commit_dev(binfo);
+}
+
+struct dfl_fpga_enum_info *dfl_fpga_enum_info_alloc(struct device *dev)
+{
+        struct dfl_fpga_enum_info *info;
+
+        get_device(dev);
+
+        info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
+        if (!info) {
+                put_device(dev);
+                return NULL;
+        }
+
+        info->dev = dev;
+        INIT_LIST_HEAD(&info->dfls);
+
+        return info;
+}
+EXPORT_SYMBOL_GPL(dfl_fpga_enum_info_alloc);
+
+void dfl_fpga_enum_info_free(struct dfl_fpga_enum_info *info)
+{
+        struct dfl_fpga_enum_dfl *tmp, *dfl;
+        struct device *dev;
+
+        if (!info)
+                return;
+
+        dev = info->dev;
+
+        /* remove all device feature lists in the list. */
+        list_for_each_entry_safe(dfl, tmp, &info->dfls, node) {
+                list_del(&dfl->node);
+                devm_kfree(dev, dfl);
+        }
+
+        devm_kfree(dev, info);
+        put_device(dev);
+}
+EXPORT_SYMBOL_GPL(dfl_fpga_enum_info_free);
+
+/**
+ * dfl_fpga_enum_info_add_dfl - add info of a device feature list to enum info
+ *
+ * @info: ptr to dfl_fpga_enum_info
+ * @start: mmio resource address of the device feature list.
+ * @len: mmio resource length of the device feature list.
+ * @ioaddr: mapped mmio resource address of the device feature list.
+ *
+ * One FPGA device may have one or more Device Feature Lists (DFLs), use this
+ * function to add information of each DFL to common data structure for next
+ * step enumeration.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int dfl_fpga_enum_info_add_dfl(struct dfl_fpga_enum_info *info,
+                               resource_size_t start, resource_size_t len,
+                               void __iomem *ioaddr)
+{
+        struct dfl_fpga_enum_dfl *dfl;
+
+        dfl = devm_kzalloc(info->dev, sizeof(*dfl), GFP_KERNEL);
+        if (!dfl)
+                return -ENOMEM;
+
+        dfl->start = start;
+        dfl->len = len;
+        dfl->ioaddr = ioaddr;
+
+        list_add_tail(&dfl->node, &info->dfls);
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(dfl_fpga_enum_info_add_dfl);
+
+static int remove_feature_dev(struct device *dev, void *data)
+{
+        struct platform_device *pdev = to_platform_device(dev);
+        enum dfl_id_type type = feature_dev_id_type(pdev);
+        int id = pdev->id;
+
+        platform_device_unregister(pdev);
+
+        dfl_id_free(type, id);
+
+        return 0;
+}
+
+static void remove_feature_devs(struct dfl_fpga_cdev *cdev)
+{
+        device_for_each_child(&cdev->region->dev, NULL, remove_feature_dev);
+}
+
+/**
+ * dfl_fpga_feature_devs_enumerate - enumerate feature devices
+ * @info: information for enumeration.
+ *
+ * This function creates a container device (base FPGA region), enumerates
+ * feature devices based on the enumeration info and creates platform devices
+ * under the container device.
+ *
+ * Return: dfl_fpga_cdev struct on success, -errno on failure
+ */
+struct dfl_fpga_cdev *
+dfl_fpga_feature_devs_enumerate(struct dfl_fpga_enum_info *info)
+{
+        struct build_feature_devs_info *binfo;
+        struct dfl_fpga_enum_dfl *dfl;
+        struct dfl_fpga_cdev *cdev;
+        int ret = 0;
+
+        if (!info->dev)
+                return ERR_PTR(-ENODEV);
+
+        cdev = devm_kzalloc(info->dev, sizeof(*cdev), GFP_KERNEL);
+        if (!cdev)
+                return ERR_PTR(-ENOMEM);
+
+        cdev->region = fpga_region_create(info->dev, NULL, NULL);
+        if (!cdev->region) {
+                ret = -ENOMEM;
+                goto free_cdev_exit;
+        }
+
+        cdev->parent = info->dev;
+        mutex_init(&cdev->lock);
+        INIT_LIST_HEAD(&cdev->port_dev_list);
+
+        ret = fpga_region_register(cdev->region);
+        if (ret)
+                goto free_region_exit;
+
+        /* create and init build info for enumeration */
+        binfo = devm_kzalloc(info->dev, sizeof(*binfo), GFP_KERNEL);
+        if (!binfo) {
+                ret = -ENOMEM;
+                goto unregister_region_exit;
+        }
+
+        binfo->dev = info->dev;
+        binfo->cdev = cdev;
+
+        /*
+         * start enumeration for all feature devices based on Device Feature
+         * Lists.
+         */
+        list_for_each_entry(dfl, &info->dfls, node) {
+                ret = parse_feature_list(binfo, dfl);
+                if (ret) {
+                        remove_feature_devs(cdev);
+                        build_info_free(binfo);
+                        goto unregister_region_exit;
+                }
+        }
+
+        build_info_free(binfo);
+
+        return cdev;
+
+unregister_region_exit:
+        fpga_region_unregister(cdev->region);
+free_region_exit:
+        fpga_region_free(cdev->region);
+free_cdev_exit:
+        devm_kfree(info->dev, cdev);
+        return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(dfl_fpga_feature_devs_enumerate);
+
+/**
+ * dfl_fpga_feature_devs_remove - remove all feature devices
+ * @cdev: fpga container device.
+ *
+ * Remove the container device and all feature devices under given container
+ * devices.
+ */
+void dfl_fpga_feature_devs_remove(struct dfl_fpga_cdev *cdev)
+{
+        struct dfl_feature_platform_data *pdata, *ptmp;
+
+        remove_feature_devs(cdev);
+
+        mutex_lock(&cdev->lock);
+        if (cdev->fme_dev) {
+                /* the fme should be unregistered. */
+                WARN_ON(device_is_registered(cdev->fme_dev));
+                put_device(cdev->fme_dev);
+        }
+
+        list_for_each_entry_safe(pdata, ptmp, &cdev->port_dev_list, node) {
+                struct platform_device *port_dev = pdata->dev;
+
+                /* the port should be unregistered. */
+                WARN_ON(device_is_registered(&port_dev->dev));
+                list_del(&pdata->node);
+                put_device(&port_dev->dev);
+        }
+        mutex_unlock(&cdev->lock);
+
+        fpga_region_unregister(cdev->region);
+        devm_kfree(cdev->parent, cdev);
+}
+EXPORT_SYMBOL_GPL(dfl_fpga_feature_devs_remove);
+
+static int __init dfl_fpga_init(void)
+{
+        dfl_ids_init();
+
+        return 0;
+}
+
+static void __exit dfl_fpga_exit(void)
+{
+        dfl_ids_destroy();
+}
+
+module_init(dfl_fpga_init);
+module_exit(dfl_fpga_exit);
+
+MODULE_DESCRIPTION("FPGA Device Feature List (DFL) Support");
+MODULE_AUTHOR("Intel Corporation");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/fpga/dfl.h b/drivers/fpga/dfl.h
new file mode 100644
index 000000000000..47ecb3bb6f61
--- /dev/null
+++ b/drivers/fpga/dfl.h
@@ -0,0 +1,279 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Driver Header File for FPGA Device Feature List (DFL) Support
+ *
+ * Copyright (C) 2017-2018 Intel Corporation, Inc.
+ *
+ * Authors:
+ *   Kang Luwei <luwei.kang@intel.com>
+ *   Zhang Yi <yi.z.zhang@intel.com>
+ *   Wu Hao <hao.wu@intel.com>
+ *   Xiao Guangrong <guangrong.xiao@linux.intel.com>
+ */
+
+#ifndef __FPGA_DFL_H
+#define __FPGA_DFL_H
+
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/fs.h>
+#include <linux/iopoll.h>
+#include <linux/io-64-nonatomic-lo-hi.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/uuid.h>
+#include <linux/fpga/fpga-region.h>
+
+/* maximum supported number of ports */
+#define MAX_DFL_FPGA_PORT_NUM 4
+/* plus one for fme device */
+#define MAX_DFL_FEATURE_DEV_NUM    (MAX_DFL_FPGA_PORT_NUM + 1)
+
+/* Reserved 0x0 for Header Group Register and 0xff for AFU */
+#define FEATURE_ID_FIU_HEADER           0x0
+#define FEATURE_ID_AFU                  0xff
+
+#define FME_FEATURE_ID_HEADER           FEATURE_ID_FIU_HEADER
+#define FME_FEATURE_ID_THERMAL_MGMT     0x1
+#define FME_FEATURE_ID_POWER_MGMT       0x2
+#define FME_FEATURE_ID_GLOBAL_IPERF     0x3
+#define FME_FEATURE_ID_GLOBAL_ERR       0x4
+#define FME_FEATURE_ID_PR_MGMT          0x5
+#define FME_FEATURE_ID_HSSI             0x6
+#define FME_FEATURE_ID_GLOBAL_DPERF     0x7
+
+#define PORT_FEATURE_ID_HEADER          FEATURE_ID_FIU_HEADER
+#define PORT_FEATURE_ID_AFU             FEATURE_ID_AFU
+#define PORT_FEATURE_ID_ERROR           0x10
+#define PORT_FEATURE_ID_UMSG            0x11
+#define PORT_FEATURE_ID_UINT            0x12
+#define PORT_FEATURE_ID_STP             0x13
+
+/*
+ * Device Feature Header Register Set
+ *
+ * For FIUs, they all have DFH + GUID + NEXT_AFU as common header registers.
+ * For AFUs, they have DFH + GUID as common header registers.
+ * For private features, they only have DFH register as common header.
+ */
+#define DFH                     0x0
+#define GUID_L                  0x8
+#define GUID_H                  0x10
+#define NEXT_AFU                0x18
+
+#define DFH_SIZE                0x8
+
+/* Device Feature Header Register Bitfield */
+#define DFH_ID                  GENMASK_ULL(11, 0)      /* Feature ID */
+#define DFH_ID_FIU_FME          0
+#define DFH_ID_FIU_PORT         1
+#define DFH_REVISION            GENMASK_ULL(15, 12)     /* Feature revision */
+#define DFH_NEXT_HDR_OFST       GENMASK_ULL(39, 16)     /* Offset to next DFH */
+#define DFH_EOL                 BIT_ULL(40)             /* End of list */
+#define DFH_TYPE                GENMASK_ULL(63, 60)     /* Feature type */
+#define DFH_TYPE_AFU            1
+#define DFH_TYPE_PRIVATE        3
+#define DFH_TYPE_FIU            4
+
+/* Next AFU Register Bitfield */
+#define NEXT_AFU_NEXT_DFH_OFST  GENMASK_ULL(23, 0)      /* Offset to next AFU */
+
+/* FME Header Register Set */
+#define FME_HDR_DFH             DFH
+#define FME_HDR_GUID_L          GUID_L
+#define FME_HDR_GUID_H          GUID_H
+#define FME_HDR_NEXT_AFU        NEXT_AFU
+#define FME_HDR_CAP             0x30
+#define FME_HDR_PORT_OFST(n)    (0x38 + ((n) * 0x8))
+#define FME_HDR_BITSTREAM_ID    0x60
+#define FME_HDR_BITSTREAM_MD    0x68
+
+/* FME Fab Capability Register Bitfield */
+#define FME_CAP_FABRIC_VERID    GENMASK_ULL(7, 0)       /* Fabric version ID */
+#define FME_CAP_SOCKET_ID       BIT_ULL(8)              /* Socket ID */
+#define FME_CAP_PCIE0_LINK_AVL  BIT_ULL(12)             /* PCIE0 Link */
+#define FME_CAP_PCIE1_LINK_AVL  BIT_ULL(13)             /* PCIE1 Link */
+#define FME_CAP_COHR_LINK_AVL   BIT_ULL(14)             /* Coherent Link */
+#define FME_CAP_IOMMU_AVL       BIT_ULL(16)             /* IOMMU available */
+#define FME_CAP_NUM_PORTS       GENMASK_ULL(19, 17)     /* Number of ports */
+#define FME_CAP_ADDR_WIDTH      GENMASK_ULL(29, 24)     /* Address bus width */
+#define FME_CAP_CACHE_SIZE      GENMASK_ULL(43, 32)     /* cache size in KB */
+#define FME_CAP_CACHE_ASSOC     GENMASK_ULL(47, 44)     /* Associativity */
+
+/* FME Port Offset Register Bitfield */
+/* Offset to port device feature header */
+#define FME_PORT_OFST_DFH_OFST  GENMASK_ULL(23, 0)
+/* PCI Bar ID for this port */
+#define FME_PORT_OFST_BAR_ID    GENMASK_ULL(34, 32)
+/* AFU MMIO access permission. 1 - VF, 0 - PF. */
+#define FME_PORT_OFST_ACC_CTRL  BIT_ULL(55)
+#define FME_PORT_OFST_ACC_PF    0
+#define FME_PORT_OFST_ACC_VF    1
+#define FME_PORT_OFST_IMP       BIT_ULL(60)
+
+/* PORT Header Register Set */
+#define PORT_HDR_DFH            DFH
+#define PORT_HDR_GUID_L         GUID_L
+#define PORT_HDR_GUID_H         GUID_H
+#define PORT_HDR_NEXT_AFU       NEXT_AFU
+#define PORT_HDR_CAP            0x30
+#define PORT_HDR_CTRL           0x38
+
+/* Port Capability Register Bitfield */
+#define PORT_CAP_PORT_NUM       GENMASK_ULL(1, 0)       /* ID of this port */
+#define PORT_CAP_MMIO_SIZE      GENMASK_ULL(23, 8)      /* MMIO size in KB */
+#define PORT_CAP_SUPP_INT_NUM   GENMASK_ULL(35, 32)     /* Interrupts num */
+
+/* Port Control Register Bitfield */
+#define PORT_CTRL_SFTRST        BIT_ULL(0)              /* Port soft reset */
+/* Latency tolerance reporting. '1' >= 40us, '0' < 40us.*/
+#define PORT_CTRL_LATENCY       BIT_ULL(2)
+#define PORT_CTRL_SFTRST_ACK    BIT_ULL(4)              /* HW ack for reset */
+
+/**
+ * struct dfl_feature - sub feature of the feature devices
+ *
+ * @id: sub feature id.
+ * @resource_index: each sub feature has one mmio resource for its registers.
+ *                  this index is used to find its mmio resource from the
+ *                  feature dev (platform device)'s reources.
+ * @ioaddr: mapped mmio resource address.
+ */
+struct dfl_feature {
+        u64 id;
+        int resource_index;
+        void __iomem *ioaddr;
+};
+
+/**
+ * struct dfl_feature_platform_data - platform data for feature devices
+ *
+ * @node: node to link feature devs to container device's port_dev_list.
+ * @lock: mutex to protect platform data.
+ * @dev: ptr to platform device linked with this platform data.
+ * @dfl_cdev: ptr to container device.
+ * @disable_count: count for port disable.
+ * @num: number for sub features.
+ * @features: sub features of this feature dev.
+ */
+struct dfl_feature_platform_data {
+        struct list_head node;
+        struct mutex lock;
+        struct platform_device *dev;
+        struct dfl_fpga_cdev *dfl_cdev;
+        unsigned int disable_count;
+
+        int num;
+        struct dfl_feature features[0];
+};
+
+#define DFL_FPGA_FEATURE_DEV_FME                "dfl-fme"
+#define DFL_FPGA_FEATURE_DEV_PORT               "dfl-port"
+
+static inline int dfl_feature_platform_data_size(const int num)
+{
+        return sizeof(struct dfl_feature_platform_data) +
+                num * sizeof(struct dfl_feature);
+}
+
+#define dfl_fpga_dev_for_each_feature(pdata, feature)                       \
+        for ((feature) = (pdata)->features;                                 \
+           (feature) < (pdata)->features + (pdata)->num; (feature)++)
+
+static inline
+struct dfl_feature *dfl_get_feature_by_id(struct device *dev, u64 id)
+{
+        struct dfl_feature_platform_data *pdata = dev_get_platdata(dev);
+        struct dfl_feature *feature;
+
+        dfl_fpga_dev_for_each_feature(pdata, feature)
+                if (feature->id == id)
+                        return feature;
+
+        return NULL;
+}
+
+static inline
+void __iomem *dfl_get_feature_ioaddr_by_id(struct device *dev, u64 id)
+{
+        struct dfl_feature *feature = dfl_get_feature_by_id(dev, id);
+
+        if (feature && feature->ioaddr)
+                return feature->ioaddr;
+
+        WARN_ON(1);
+        return NULL;
+}
+
+static inline bool dfl_feature_is_fme(void __iomem *base)
+{
+        u64 v = readq(base + DFH);
+
+        return (FIELD_GET(DFH_TYPE, v) == DFH_TYPE_FIU) &&
+                (FIELD_GET(DFH_ID, v) == DFH_ID_FIU_FME);
+}
+
+static inline bool dfl_feature_is_port(void __iomem *base)
+{
+        u64 v = readq(base + DFH);
+
+        return (FIELD_GET(DFH_TYPE, v) == DFH_TYPE_FIU) &&
+                (FIELD_GET(DFH_ID, v) == DFH_ID_FIU_PORT);
+}
+
+/**
+ * struct dfl_fpga_enum_info - DFL FPGA enumeration information
+ *
+ * @dev: parent device.
+ * @dfls: list of device feature lists.
+ */
+struct dfl_fpga_enum_info {
+        struct device *dev;
+        struct list_head dfls;
+};
+
+/**
+ * struct dfl_fpga_enum_dfl - DFL FPGA enumeration device feature list info
+ *
+ * @start: base address of this device feature list.
+ * @len: size of this device feature list.
+ * @ioaddr: mapped base address of this device feature list.
+ * @node: node in list of device feature lists.
+ */
+struct dfl_fpga_enum_dfl {
+        resource_size_t start;
+        resource_size_t len;
+
+        void __iomem *ioaddr;
+
+        struct list_head node;
+};
+
+struct dfl_fpga_enum_info *dfl_fpga_enum_info_alloc(struct device *dev);
+int dfl_fpga_enum_info_add_dfl(struct dfl_fpga_enum_info *info,
+                               resource_size_t start, resource_size_t len,
+                               void __iomem *ioaddr);
+void dfl_fpga_enum_info_free(struct dfl_fpga_enum_info *info);
+
+/**
+ * struct dfl_fpga_cdev - container device of DFL based FPGA
+ *
+ * @parent: parent device of this container device.
+ * @region: base fpga region.
+ * @fme_dev: FME feature device under this container device.
+ * @lock: mutex lock to protect the port device list.
+ * @port_dev_list: list of all port feature devices under this container device.
+ */
+struct dfl_fpga_cdev {
+        struct device *parent;
+        struct fpga_region *region;
+        struct device *fme_dev;
+        struct mutex lock;
+        struct list_head port_dev_list;
+};
+
+struct dfl_fpga_cdev *
+dfl_fpga_feature_devs_enumerate(struct dfl_fpga_enum_info *info);
+void dfl_fpga_feature_devs_remove(struct dfl_fpga_cdev *cdev);
+
+#endif /* __FPGA_DFL_H */