// SPDX-License-Identifier: GPL-2.0-only
/*
 * Arm Firmware Framework for ARMv8-A(FFA) interface driver
 *
 * The Arm FFA specification[1] describes a software architecture to
 * leverages the virtualization extension to isolate software images
 * provided by an ecosystem of vendors from each other and describes
 * interfaces that standardize communication between the various software
 * images including communication between images in the Secure world and
 * Normal world. Any Hypervisor could use the FFA interfaces to enable
 * communication between VMs it manages.
 *
 * The Hypervisor a.k.a Partition managers in FFA terminology can assign
 * system resources(Memory regions, Devices, CPU cycles) to the partitions
 * and manage isolation amongst them.
 *
 * [1] https://developer.arm.com/docs/den0077/latest
 *
 * Copyright (C) 2021 ARM Ltd.
 */

#define DRIVER_NAME "ARM FF-A"
#define pr_fmt(fmt) DRIVER_NAME ": " fmt

#include <linux/arm_ffa.h>
#include <linux/bitfield.h>
#include <linux/device.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <linux/uuid.h>

#include "common.h"

#define FFA_DRIVER_VERSION      FFA_VERSION_1_0

#define FFA_SMC(calling_convention, func_num)                           \
        ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, (calling_convention),   \
                           ARM_SMCCC_OWNER_STANDARD, (func_num))

#define FFA_SMC_32(func_num)    FFA_SMC(ARM_SMCCC_SMC_32, (func_num))
#define FFA_SMC_64(func_num)    FFA_SMC(ARM_SMCCC_SMC_64, (func_num))

#define FFA_ERROR                       FFA_SMC_32(0x60)
#define FFA_SUCCESS                     FFA_SMC_32(0x61)
#define FFA_INTERRUPT                   FFA_SMC_32(0x62)
#define FFA_VERSION                     FFA_SMC_32(0x63)
#define FFA_FEATURES                    FFA_SMC_32(0x64)
#define FFA_RX_RELEASE                  FFA_SMC_32(0x65)
#define FFA_RXTX_MAP                    FFA_SMC_32(0x66)
#define FFA_FN64_RXTX_MAP               FFA_SMC_64(0x66)
#define FFA_RXTX_UNMAP                  FFA_SMC_32(0x67)
#define FFA_PARTITION_INFO_GET          FFA_SMC_32(0x68)
#define FFA_ID_GET                      FFA_SMC_32(0x69)
#define FFA_MSG_POLL                    FFA_SMC_32(0x6A)
#define FFA_MSG_WAIT                    FFA_SMC_32(0x6B)
#define FFA_YIELD                       FFA_SMC_32(0x6C)
#define FFA_RUN                         FFA_SMC_32(0x6D)
#define FFA_MSG_SEND                    FFA_SMC_32(0x6E)
#define FFA_MSG_SEND_DIRECT_REQ         FFA_SMC_32(0x6F)
#define FFA_FN64_MSG_SEND_DIRECT_REQ    FFA_SMC_64(0x6F)
#define FFA_MSG_SEND_DIRECT_RESP        FFA_SMC_32(0x70)
#define FFA_FN64_MSG_SEND_DIRECT_RESP   FFA_SMC_64(0x70)
#define FFA_MEM_DONATE                  FFA_SMC_32(0x71)
#define FFA_FN64_MEM_DONATE             FFA_SMC_64(0x71)
#define FFA_MEM_LEND                    FFA_SMC_32(0x72)
#define FFA_FN64_MEM_LEND               FFA_SMC_64(0x72)
#define FFA_MEM_SHARE                   FFA_SMC_32(0x73)
#define FFA_FN64_MEM_SHARE              FFA_SMC_64(0x73)
#define FFA_MEM_RETRIEVE_REQ            FFA_SMC_32(0x74)
#define FFA_FN64_MEM_RETRIEVE_REQ       FFA_SMC_64(0x74)
#define FFA_MEM_RETRIEVE_RESP           FFA_SMC_32(0x75)
#define FFA_MEM_RELINQUISH              FFA_SMC_32(0x76)
#define FFA_MEM_RECLAIM                 FFA_SMC_32(0x77)
#define FFA_MEM_OP_PAUSE                FFA_SMC_32(0x78)
#define FFA_MEM_OP_RESUME               FFA_SMC_32(0x79)
#define FFA_MEM_FRAG_RX                 FFA_SMC_32(0x7A)
#define FFA_MEM_FRAG_TX                 FFA_SMC_32(0x7B)
#define FFA_NORMAL_WORLD_RESUME         FFA_SMC_32(0x7C)

/*
 * For some calls it is necessary to use SMC64 to pass or return 64-bit values.
 * For such calls FFA_FN_NATIVE(name) will choose the appropriate
 * (native-width) function ID.
 */
#ifdef CONFIG_64BIT
#define FFA_FN_NATIVE(name)     FFA_FN64_##name
#else
#define FFA_FN_NATIVE(name)     FFA_##name
#endif

/* FFA error codes. */
#define FFA_RET_SUCCESS            (0)
#define FFA_RET_NOT_SUPPORTED      (-1)
#define FFA_RET_INVALID_PARAMETERS (-2)
#define FFA_RET_NO_MEMORY          (-3)
#define FFA_RET_BUSY               (-4)
#define FFA_RET_INTERRUPTED        (-5)
#define FFA_RET_DENIED             (-6)
#define FFA_RET_RETRY              (-7)
#define FFA_RET_ABORTED            (-8)

#define MAJOR_VERSION_MASK      GENMASK(30, 16)
#define MINOR_VERSION_MASK      GENMASK(15, 0)
#define MAJOR_VERSION(x)        ((u16)(FIELD_GET(MAJOR_VERSION_MASK, (x))))
#define MINOR_VERSION(x)        ((u16)(FIELD_GET(MINOR_VERSION_MASK, (x))))
#define PACK_VERSION_INFO(major, minor)                 \
        (FIELD_PREP(MAJOR_VERSION_MASK, (major)) |      \
         FIELD_PREP(MINOR_VERSION_MASK, (minor)))
#define FFA_VERSION_1_0         PACK_VERSION_INFO(1, 0)
#define FFA_MIN_VERSION         FFA_VERSION_1_0

#define SENDER_ID_MASK          GENMASK(31, 16)
#define RECEIVER_ID_MASK        GENMASK(15, 0)
#define SENDER_ID(x)            ((u16)(FIELD_GET(SENDER_ID_MASK, (x))))
#define RECEIVER_ID(x)          ((u16)(FIELD_GET(RECEIVER_ID_MASK, (x))))
#define PACK_TARGET_INFO(s, r)          \
        (FIELD_PREP(SENDER_ID_MASK, (s)) | FIELD_PREP(RECEIVER_ID_MASK, (r)))

/*
 * FF-A specification mentions explicitly about '4K pages'. This should
 * not be confused with the kernel PAGE_SIZE, which is the translation
 * granule kernel is configured and may be one among 4K, 16K and 64K.
 */
#define FFA_PAGE_SIZE           SZ_4K
/*
 * Keeping RX TX buffer size as 4K for now
 * 64K may be preferred to keep it min a page in 64K PAGE_SIZE config
 */
#define RXTX_BUFFER_SIZE        SZ_4K

static ffa_fn *invoke_ffa_fn;

static const int ffa_linux_errmap[] = {
        /* better than switch case as long as return value is continuous */
        0,              /* FFA_RET_SUCCESS */
        -EOPNOTSUPP,    /* FFA_RET_NOT_SUPPORTED */
        -EINVAL,        /* FFA_RET_INVALID_PARAMETERS */
        -ENOMEM,        /* FFA_RET_NO_MEMORY */
        -EBUSY,         /* FFA_RET_BUSY */
        -EINTR,         /* FFA_RET_INTERRUPTED */
        -EACCES,        /* FFA_RET_DENIED */
        -EAGAIN,        /* FFA_RET_RETRY */
        -ECANCELED,     /* FFA_RET_ABORTED */
};

static inline int ffa_to_linux_errno(int errno)
{
        int err_idx = -errno;

        if (err_idx >= 0 && err_idx < ARRAY_SIZE(ffa_linux_errmap))
                return ffa_linux_errmap[err_idx];
        return -EINVAL;
}

struct ffa_drv_info {
        u32 version;
        u16 vm_id;
        struct mutex rx_lock; /* lock to protect Rx buffer */
        struct mutex tx_lock; /* lock to protect Tx buffer */
        void *rx_buffer;
        void *tx_buffer;
};

static struct ffa_drv_info *drv_info;

static int ffa_version_check(u32 *version)
{
        ffa_value_t ver;

        invoke_ffa_fn((ffa_value_t){
                      .a0 = FFA_VERSION, .a1 = FFA_DRIVER_VERSION,
                      }, &ver);

        if (ver.a0 == FFA_RET_NOT_SUPPORTED) {
                pr_info("FFA_VERSION returned not supported\n");
                return -EOPNOTSUPP;
        }

        if (ver.a0 < FFA_MIN_VERSION || ver.a0 > FFA_DRIVER_VERSION) {
                pr_err("Incompatible version %d.%d found\n",
                       MAJOR_VERSION(ver.a0), MINOR_VERSION(ver.a0));
                return -EINVAL;
        }

        *version = ver.a0;
        pr_info("Version %d.%d found\n", MAJOR_VERSION(ver.a0),
                MINOR_VERSION(ver.a0));
        return 0;
}

static int ffa_rx_release(void)
{
        ffa_value_t ret;

        invoke_ffa_fn((ffa_value_t){
                      .a0 = FFA_RX_RELEASE,
                      }, &ret);

        if (ret.a0 == FFA_ERROR)
                return ffa_to_linux_errno((int)ret.a2);

        /* check for ret.a0 == FFA_RX_RELEASE ? */

        return 0;
}

static int ffa_rxtx_map(phys_addr_t tx_buf, phys_addr_t rx_buf, u32 pg_cnt)
{
        ffa_value_t ret;

        invoke_ffa_fn((ffa_value_t){
                      .a0 = FFA_FN_NATIVE(RXTX_MAP),
                      .a1 = tx_buf, .a2 = rx_buf, .a3 = pg_cnt,
                      }, &ret);

        if (ret.a0 == FFA_ERROR)
                return ffa_to_linux_errno((int)ret.a2);

        return 0;
}

static int ffa_rxtx_unmap(u16 vm_id)
{
        ffa_value_t ret;

        invoke_ffa_fn((ffa_value_t){
                      .a0 = FFA_RXTX_UNMAP, .a1 = PACK_TARGET_INFO(vm_id, 0),
                      }, &ret);

        if (ret.a0 == FFA_ERROR)
                return ffa_to_linux_errno((int)ret.a2);

        return 0;
}

/* buffer must be sizeof(struct ffa_partition_info) * num_partitions */
static int
__ffa_partition_info_get(u32 uuid0, u32 uuid1, u32 uuid2, u32 uuid3,
                         struct ffa_partition_info *buffer, int num_partitions)
{
        int count;
        ffa_value_t partition_info;

        mutex_lock(&drv_info->rx_lock);
        invoke_ffa_fn((ffa_value_t){
                      .a0 = FFA_PARTITION_INFO_GET,
                      .a1 = uuid0, .a2 = uuid1, .a3 = uuid2, .a4 = uuid3,
                      }, &partition_info);

        if (partition_info.a0 == FFA_ERROR) {
                mutex_unlock(&drv_info->rx_lock);
                return ffa_to_linux_errno((int)partition_info.a2);
        }

        count = partition_info.a2;

        if (buffer && count <= num_partitions)
                memcpy(buffer, drv_info->rx_buffer, sizeof(*buffer) * count);

        ffa_rx_release();

        mutex_unlock(&drv_info->rx_lock);

        return count;
}

/* buffer is allocated and caller must free the same if returned count > 0 */
static int
ffa_partition_probe(const uuid_t *uuid, struct ffa_partition_info **buffer)
{
        int count;
        u32 uuid0_4[4];
        struct ffa_partition_info *pbuf;

        export_uuid((u8 *)uuid0_4, uuid);
        count = __ffa_partition_info_get(uuid0_4[0], uuid0_4[1], uuid0_4[2],
                                         uuid0_4[3], NULL, 0);
        if (count <= 0)
                return count;

        pbuf = kcalloc(count, sizeof(*pbuf), GFP_KERNEL);
        if (!pbuf)
                return -ENOMEM;

        count = __ffa_partition_info_get(uuid0_4[0], uuid0_4[1], uuid0_4[2],
                                         uuid0_4[3], pbuf, count);
        if (count <= 0)
                kfree(pbuf);
        else
                *buffer = pbuf;

        return count;
}

#define VM_ID_MASK      GENMASK(15, 0)
static int ffa_id_get(u16 *vm_id)
{
        ffa_value_t id;

        invoke_ffa_fn((ffa_value_t){
                      .a0 = FFA_ID_GET,
                      }, &id);

        if (id.a0 == FFA_ERROR)
                return ffa_to_linux_errno((int)id.a2);

        *vm_id = FIELD_GET(VM_ID_MASK, (id.a2));

        return 0;
}

static int ffa_msg_send_direct_req(u16 src_id, u16 dst_id, bool mode_32bit,
                                   struct ffa_send_direct_data *data)
{
        u32 req_id, resp_id, src_dst_ids = PACK_TARGET_INFO(src_id, dst_id);
        ffa_value_t ret;

        if (mode_32bit) {
                req_id = FFA_MSG_SEND_DIRECT_REQ;
                resp_id = FFA_MSG_SEND_DIRECT_RESP;
        } else {
                req_id = FFA_FN_NATIVE(MSG_SEND_DIRECT_REQ);
                resp_id = FFA_FN_NATIVE(MSG_SEND_DIRECT_RESP);
        }

        invoke_ffa_fn((ffa_value_t){
                      .a0 = req_id, .a1 = src_dst_ids, .a2 = 0,
                      .a3 = data->data0, .a4 = data->data1, .a5 = data->data2,
                      .a6 = data->data3, .a7 = data->data4,
                      }, &ret);

        while (ret.a0 == FFA_INTERRUPT)
                invoke_ffa_fn((ffa_value_t){
                              .a0 = FFA_RUN, .a1 = ret.a1,
                              }, &ret);

        if (ret.a0 == FFA_ERROR)
                return ffa_to_linux_errno((int)ret.a2);

        if (ret.a0 == resp_id) {
                data->data0 = ret.a3;
                data->data1 = ret.a4;
                data->data2 = ret.a5;
                data->data3 = ret.a6;
                data->data4 = ret.a7;
                return 0;
        }

        return -EINVAL;
}

static int ffa_mem_first_frag(u32 func_id, phys_addr_t buf, u32 buf_sz,
                              u32 frag_len, u32 len, u64 *handle)
{
        ffa_value_t ret;

        invoke_ffa_fn((ffa_value_t){
                      .a0 = func_id, .a1 = len, .a2 = frag_len,
                      .a3 = buf, .a4 = buf_sz,
                      }, &ret);

        while (ret.a0 == FFA_MEM_OP_PAUSE)
                invoke_ffa_fn((ffa_value_t){
                              .a0 = FFA_MEM_OP_RESUME,
                              .a1 = ret.a1, .a2 = ret.a2,
                              }, &ret);

        if (ret.a0 == FFA_ERROR)
                return ffa_to_linux_errno((int)ret.a2);

        if (ret.a0 != FFA_SUCCESS)
                return -EOPNOTSUPP;

        if (handle)
                *handle = PACK_HANDLE(ret.a2, ret.a3);

        return frag_len;
}

static int ffa_mem_next_frag(u64 handle, u32 frag_len)
{
        ffa_value_t ret;

        invoke_ffa_fn((ffa_value_t){
                      .a0 = FFA_MEM_FRAG_TX,
                      .a1 = HANDLE_LOW(handle), .a2 = HANDLE_HIGH(handle),
                      .a3 = frag_len,
                      }, &ret);

        while (ret.a0 == FFA_MEM_OP_PAUSE)
                invoke_ffa_fn((ffa_value_t){
                              .a0 = FFA_MEM_OP_RESUME,
                              .a1 = ret.a1, .a2 = ret.a2,
                              }, &ret);

        if (ret.a0 == FFA_ERROR)
                return ffa_to_linux_errno((int)ret.a2);

        if (ret.a0 != FFA_MEM_FRAG_RX)
                return -EOPNOTSUPP;

        return ret.a3;
}

static int
ffa_transmit_fragment(u32 func_id, phys_addr_t buf, u32 buf_sz, u32 frag_len,
                      u32 len, u64 *handle, bool first)
{
        if (!first)
                return ffa_mem_next_frag(*handle, frag_len);

        return ffa_mem_first_frag(func_id, buf, buf_sz, frag_len, len, handle);
}

static u32 ffa_get_num_pages_sg(struct scatterlist *sg)
{
        u32 num_pages = 0;

        do {
                num_pages += sg->length / FFA_PAGE_SIZE;
        } while ((sg = sg_next(sg)));

        return num_pages;
}

static int
ffa_setup_and_transmit(u32 func_id, void *buffer, u32 max_fragsize,
                       struct ffa_mem_ops_args *args)
{
        int rc = 0;
        bool first = true;
        phys_addr_t addr = 0;
        struct ffa_composite_mem_region *composite;
        struct ffa_mem_region_addr_range *constituents;
        struct ffa_mem_region_attributes *ep_mem_access;
        struct ffa_mem_region *mem_region = buffer;
        u32 idx, frag_len, length, buf_sz = 0, num_entries = sg_nents(args->sg);

        mem_region->tag = args->tag;
        mem_region->flags = args->flags;
        mem_region->sender_id = drv_info->vm_id;
        mem_region->attributes = FFA_MEM_NORMAL | FFA_MEM_WRITE_BACK |
                                 FFA_MEM_INNER_SHAREABLE;
        ep_mem_access = &mem_region->ep_mem_access[0];

        for (idx = 0; idx < args->nattrs; idx++, ep_mem_access++) {
                ep_mem_access->receiver = args->attrs[idx].receiver;
                ep_mem_access->attrs = args->attrs[idx].attrs;
                ep_mem_access->composite_off = COMPOSITE_OFFSET(args->nattrs);
        }
        mem_region->ep_count = args->nattrs;

        composite = buffer + COMPOSITE_OFFSET(args->nattrs);
        composite->total_pg_cnt = ffa_get_num_pages_sg(args->sg);
        composite->addr_range_cnt = num_entries;

        length = COMPOSITE_CONSTITUENTS_OFFSET(args->nattrs, num_entries);
        frag_len = COMPOSITE_CONSTITUENTS_OFFSET(args->nattrs, 0);
        if (frag_len > max_fragsize)
                return -ENXIO;

        if (!args->use_txbuf) {
                addr = virt_to_phys(buffer);
                buf_sz = max_fragsize / FFA_PAGE_SIZE;
        }

        constituents = buffer + frag_len;
        idx = 0;
        do {
                if (frag_len == max_fragsize) {
                        rc = ffa_transmit_fragment(func_id, addr, buf_sz,
                                                   frag_len, length,
                                                   &args->g_handle, first);
                        if (rc < 0)
                                return -ENXIO;

                        first = false;
                        idx = 0;
                        frag_len = 0;
                        constituents = buffer;
                }

                if ((void *)constituents - buffer > max_fragsize) {
                        pr_err("Memory Region Fragment > Tx Buffer size\n");
                        return -EFAULT;
                }

                constituents->address = sg_phys(args->sg);
                constituents->pg_cnt = args->sg->length / FFA_PAGE_SIZE;
                constituents++;
                frag_len += sizeof(struct ffa_mem_region_addr_range);
        } while ((args->sg = sg_next(args->sg)));

        return ffa_transmit_fragment(func_id, addr, buf_sz, frag_len,
                                     length, &args->g_handle, first);
}

static int ffa_memory_ops(u32 func_id, struct ffa_mem_ops_args *args)
{
        int ret;
        void *buffer;

        if (!args->use_txbuf) {
                buffer = alloc_pages_exact(RXTX_BUFFER_SIZE, GFP_KERNEL);
                if (!buffer)
                        return -ENOMEM;
        } else {
                buffer = drv_info->tx_buffer;
                mutex_lock(&drv_info->tx_lock);
        }

        ret = ffa_setup_and_transmit(func_id, buffer, RXTX_BUFFER_SIZE, args);

        if (args->use_txbuf)
                mutex_unlock(&drv_info->tx_lock);
        else
                free_pages_exact(buffer, RXTX_BUFFER_SIZE);

        return ret < 0 ? ret : 0;
}

static int ffa_memory_reclaim(u64 g_handle, u32 flags)
{
        ffa_value_t ret;

        invoke_ffa_fn((ffa_value_t){
                      .a0 = FFA_MEM_RECLAIM,
                      .a1 = HANDLE_LOW(g_handle), .a2 = HANDLE_HIGH(g_handle),
                      .a3 = flags,
                      }, &ret);

        if (ret.a0 == FFA_ERROR)
                return ffa_to_linux_errno((int)ret.a2);

        return 0;
}

static u32 ffa_api_version_get(void)
{
        return drv_info->version;
}

static int ffa_partition_info_get(const char *uuid_str,
                                  struct ffa_partition_info *buffer)
{
        int count;
        uuid_t uuid;
        struct ffa_partition_info *pbuf;

        if (uuid_parse(uuid_str, &uuid)) {
                pr_err("invalid uuid (%s)\n", uuid_str);
                return -ENODEV;
        }

        count = ffa_partition_probe(&uuid_null, &pbuf);
        if (count <= 0)
                return -ENOENT;

        memcpy(buffer, pbuf, sizeof(*pbuf) * count);
        kfree(pbuf);
        return 0;
}

static void ffa_mode_32bit_set(struct ffa_device *dev)
{
        dev->mode_32bit = true;
}

static int ffa_sync_send_receive(struct ffa_device *dev,
                                 struct ffa_send_direct_data *data)
{
        return ffa_msg_send_direct_req(drv_info->vm_id, dev->vm_id,
                                       dev->mode_32bit, data);
}

static int
ffa_memory_share(struct ffa_device *dev, struct ffa_mem_ops_args *args)
{
        if (dev->mode_32bit)
                return ffa_memory_ops(FFA_MEM_SHARE, args);

        return ffa_memory_ops(FFA_FN_NATIVE(MEM_SHARE), args);
}

static const struct ffa_dev_ops ffa_ops = {
        .api_version_get = ffa_api_version_get,
        .partition_info_get = ffa_partition_info_get,
        .mode_32bit_set = ffa_mode_32bit_set,
        .sync_send_receive = ffa_sync_send_receive,
        .memory_reclaim = ffa_memory_reclaim,
        .memory_share = ffa_memory_share,
};

const struct ffa_dev_ops *ffa_dev_ops_get(struct ffa_device *dev)
{
        if (ffa_device_is_valid(dev))
                return &ffa_ops;

        return NULL;
}
EXPORT_SYMBOL_GPL(ffa_dev_ops_get);

void ffa_device_match_uuid(struct ffa_device *ffa_dev, const uuid_t *uuid)
{
        int count, idx;
        struct ffa_partition_info *pbuf, *tpbuf;

        count = ffa_partition_probe(uuid, &pbuf);
        if (count <= 0)
                return;

        for (idx = 0, tpbuf = pbuf; idx < count; idx++, tpbuf++)
                if (tpbuf->id == ffa_dev->vm_id)
                        uuid_copy(&ffa_dev->uuid, uuid);
        kfree(pbuf);
}

static void ffa_setup_partitions(void)
{
        int count, idx;
        struct ffa_device *ffa_dev;
        struct ffa_partition_info *pbuf, *tpbuf;

        count = ffa_partition_probe(&uuid_null, &pbuf);
        if (count <= 0) {
                pr_info("%s: No partitions found, error %d\n", __func__, count);
                return;
        }

        for (idx = 0, tpbuf = pbuf; idx < count; idx++, tpbuf++) {
                /* Note that the &uuid_null parameter will require
                 * ffa_device_match() to find the UUID of this partition id
                 * with help of ffa_device_match_uuid(). Once the FF-A spec
                 * is updated to provide correct UUID here for each partition
                 * as part of the discovery API, we need to pass the
                 * discovered UUID here instead.
                 */
                ffa_dev = ffa_device_register(&uuid_null, tpbuf->id);
                if (!ffa_dev) {
                        pr_err("%s: failed to register partition ID 0x%x\n",
                               __func__, tpbuf->id);
                        continue;
                }

                ffa_dev_set_drvdata(ffa_dev, drv_info);
        }
        kfree(pbuf);
}

static int __init ffa_init(void)
{
        int ret;

        ret = ffa_transport_init(&invoke_ffa_fn);
        if (ret)
                return ret;

        ret = arm_ffa_bus_init();
        if (ret)
                return ret;

        drv_info = kzalloc(sizeof(*drv_info), GFP_KERNEL);
        if (!drv_info) {
                ret = -ENOMEM;
                goto ffa_bus_exit;
        }

        ret = ffa_version_check(&drv_info->version);
        if (ret)
                goto free_drv_info;

        if (ffa_id_get(&drv_info->vm_id)) {
                pr_err("failed to obtain VM id for self\n");
                ret = -ENODEV;
                goto free_drv_info;
        }

        drv_info->rx_buffer = alloc_pages_exact(RXTX_BUFFER_SIZE, GFP_KERNEL);
        if (!drv_info->rx_buffer) {
                ret = -ENOMEM;
                goto free_pages;
        }

        drv_info->tx_buffer = alloc_pages_exact(RXTX_BUFFER_SIZE, GFP_KERNEL);
        if (!drv_info->tx_buffer) {
                ret = -ENOMEM;
                goto free_pages;
        }

        ret = ffa_rxtx_map(virt_to_phys(drv_info->tx_buffer),
                           virt_to_phys(drv_info->rx_buffer),
                           RXTX_BUFFER_SIZE / FFA_PAGE_SIZE);
        if (ret) {
                pr_err("failed to register FFA RxTx buffers\n");
                goto free_pages;
        }

        mutex_init(&drv_info->rx_lock);
        mutex_init(&drv_info->tx_lock);

        ffa_setup_partitions();

        return 0;
free_pages:
        if (drv_info->tx_buffer)
                free_pages_exact(drv_info->tx_buffer, RXTX_BUFFER_SIZE);
        free_pages_exact(drv_info->rx_buffer, RXTX_BUFFER_SIZE);
free_drv_info:
        kfree(drv_info);
ffa_bus_exit:
        arm_ffa_bus_exit();
        return ret;
}
subsys_initcall(ffa_init);

static void __exit ffa_exit(void)
{
        ffa_rxtx_unmap(drv_info->vm_id);
        free_pages_exact(drv_info->tx_buffer, RXTX_BUFFER_SIZE);
        free_pages_exact(drv_info->rx_buffer, RXTX_BUFFER_SIZE);
        kfree(drv_info);
        arm_ffa_bus_exit();
}
module_exit(ffa_exit);

MODULE_ALIAS("arm-ffa");
MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
MODULE_DESCRIPTION("Arm FF-A interface driver");
MODULE_LICENSE("GPL v2");