/*
 * Remote Processor Framework
 *
 * Copyright (C) 2011 Texas Instruments, Inc.
 * Copyright (C) 2011 Google, Inc.
 *
 * Ohad Ben-Cohen <ohad@wizery.com>
 * Brian Swetland <swetland@google.com>
 * Mark Grosen <mgrosen@ti.com>
 * Fernando Guzman Lugo <fernando.lugo@ti.com>
 * Suman Anna <s-anna@ti.com>
 * Robert Tivy <rtivy@ti.com>
 * Armando Uribe De Leon <x0095078@ti.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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#define pr_fmt(fmt)    "%s: " fmt, __func__

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/dma-mapping.h>
#include <linux/firmware.h>
#include <linux/string.h>
#include <linux/debugfs.h>
#include <linux/remoteproc.h>
#include <linux/iommu.h>
#include <linux/idr.h>
#include <linux/elf.h>
#include <linux/virtio_ids.h>
#include <linux/virtio_ring.h>
#include <asm/byteorder.h>

#include "remoteproc_internal.h"

typedef int (*rproc_handle_resources_t)(struct rproc *rproc,
                                struct resource_table *table, int len);
typedef int (*rproc_handle_resource_t)(struct rproc *rproc, void *, int avail);

/* Unique indices for remoteproc devices */
static DEFINE_IDA(rproc_dev_index);

/*
 * This is the IOMMU fault handler we register with the IOMMU API
 * (when relevant; not all remote processors access memory through
 * an IOMMU).
 *
 * IOMMU core will invoke this handler whenever the remote processor
 * will try to access an unmapped device address.
 *
 * Currently this is mostly a stub, but it will be later used to trigger
 * the recovery of the remote processor.
 */
static int rproc_iommu_fault(struct iommu_domain *domain, struct device *dev,
                unsigned long iova, int flags, void *token)
{
        dev_err(dev, "iommu fault: da 0x%lx flags 0x%x\n", iova, flags);

        /*
         * Let the iommu core know we're not really handling this fault;
         * we just plan to use this as a recovery trigger.
         */
        return -ENOSYS;
}

static int rproc_enable_iommu(struct rproc *rproc)
{
        struct iommu_domain *domain;
        struct device *dev = rproc->dev.parent;
        int ret;

        /*
         * We currently use iommu_present() to decide if an IOMMU
         * setup is needed.
         *
         * This works for simple cases, but will easily fail with
         * platforms that do have an IOMMU, but not for this specific
         * rproc.
         *
         * This will be easily solved by introducing hw capabilities
         * that will be set by the remoteproc driver.
         */
        if (!iommu_present(dev->bus)) {
                dev_dbg(dev, "iommu not found\n");
                return 0;
        }

        domain = iommu_domain_alloc(dev->bus);
        if (!domain) {
                dev_err(dev, "can't alloc iommu domain\n");
                return -ENOMEM;
        }

        iommu_set_fault_handler(domain, rproc_iommu_fault, rproc);

        ret = iommu_attach_device(domain, dev);
        if (ret) {
                dev_err(dev, "can't attach iommu device: %d\n", ret);
                goto free_domain;
        }

        rproc->domain = domain;

        return 0;

free_domain:
        iommu_domain_free(domain);
        return ret;
}

static void rproc_disable_iommu(struct rproc *rproc)
{
        struct iommu_domain *domain = rproc->domain;
        struct device *dev = rproc->dev.parent;

        if (!domain)
                return;

        iommu_detach_device(domain, dev);
        iommu_domain_free(domain);

        return;
}

/*
 * Some remote processors will ask us to allocate them physically contiguous
 * memory regions (which we call "carveouts"), and map them to specific
 * device addresses (which are hardcoded in the firmware).
 *
 * They may then ask us to copy objects into specific device addresses (e.g.
 * code/data sections) or expose us certain symbols in other device address
 * (e.g. their trace buffer).
 *
 * This function is an internal helper with which we can go over the allocated
 * carveouts and translate specific device address to kernel virtual addresses
 * so we can access the referenced memory.
 *
 * Note: phys_to_virt(iommu_iova_to_phys(rproc->domain, da)) will work too,
 * but only on kernel direct mapped RAM memory. Instead, we're just using
 * here the output of the DMA API, which should be more correct.
 */
void *rproc_da_to_va(struct rproc *rproc, u64 da, int len)
{
        struct rproc_mem_entry *carveout;
        void *ptr = NULL;

        list_for_each_entry(carveout, &rproc->carveouts, node) {
                int offset = da - carveout->da;

                /* try next carveout if da is too small */
                if (offset < 0)
                        continue;

                /* try next carveout if da is too large */
                if (offset + len > carveout->len)
                        continue;

                ptr = carveout->va + offset;

                break;
        }

        return ptr;
}
EXPORT_SYMBOL(rproc_da_to_va);

int rproc_alloc_vring(struct rproc_vdev *rvdev, int i)
{
        struct rproc *rproc = rvdev->rproc;
        struct device *dev = &rproc->dev;
        struct rproc_vring *rvring = &rvdev->vring[i];
        dma_addr_t dma;
        void *va;
        int ret, size, notifyid;

        /* actual size of vring (in bytes) */
        size = PAGE_ALIGN(vring_size(rvring->len, rvring->align));

        if (!idr_pre_get(&rproc->notifyids, GFP_KERNEL)) {
                dev_err(dev, "idr_pre_get failed\n");
                return -ENOMEM;
        }

        /*
         * Allocate non-cacheable memory for the vring. In the future
         * this call will also configure the IOMMU for us
         * TODO: let the rproc know the da of this vring
         */
        va = dma_alloc_coherent(dev->parent, size, &dma, GFP_KERNEL);
        if (!va) {
                dev_err(dev->parent, "dma_alloc_coherent failed\n");
                return -EINVAL;
        }

        /*
         * Assign an rproc-wide unique index for this vring
         * TODO: assign a notifyid for rvdev updates as well
         * TODO: let the rproc know the notifyid of this vring
         * TODO: support predefined notifyids (via resource table)
         */
        ret = idr_get_new(&rproc->notifyids, rvring, &notifyid);
        if (ret) {
                dev_err(dev, "idr_get_new failed: %d\n", ret);
                dma_free_coherent(dev->parent, size, va, dma);
                return ret;
        }

        dev_dbg(dev, "vring%d: va %p dma %x size %x idr %d\n", i, va,
                                        dma, size, notifyid);

        rvring->va = va;
        rvring->dma = dma;
        rvring->notifyid = notifyid;

        return 0;
}

static int
rproc_parse_vring(struct rproc_vdev *rvdev, struct fw_rsc_vdev *rsc, int i)
{
        struct rproc *rproc = rvdev->rproc;
        struct device *dev = &rproc->dev;
        struct fw_rsc_vdev_vring *vring = &rsc->vring[i];
        struct rproc_vring *rvring = &rvdev->vring[i];

        dev_dbg(dev, "vdev rsc: vring%d: da %x, qsz %d, align %d\n",
                                i, vring->da, vring->num, vring->align);

        /* make sure reserved bytes are zeroes */
        if (vring->reserved) {
                dev_err(dev, "vring rsc has non zero reserved bytes\n");
                return -EINVAL;
        }

        /* verify queue size and vring alignment are sane */
        if (!vring->num || !vring->align) {
                dev_err(dev, "invalid qsz (%d) or alignment (%d)\n",
                                                vring->num, vring->align);
                return -EINVAL;
        }

        rvring->len = vring->num;
        rvring->align = vring->align;
        rvring->rvdev = rvdev;

        return 0;
}

void rproc_free_vring(struct rproc_vring *rvring)
{
        int size = PAGE_ALIGN(vring_size(rvring->len, rvring->align));
        struct rproc *rproc = rvring->rvdev->rproc;

        dma_free_coherent(rproc->dev.parent, size, rvring->va, rvring->dma);
        idr_remove(&rproc->notifyids, rvring->notifyid);
}

/**
 * rproc_handle_vdev() - handle a vdev fw resource
 * @rproc: the remote processor
 * @rsc: the vring resource descriptor
 * @avail: size of available data (for sanity checking the image)
 *
 * This resource entry requests the host to statically register a virtio
 * device (vdev), and setup everything needed to support it. It contains
 * everything needed to make it possible: the virtio device id, virtio
 * device features, vrings information, virtio config space, etc...
 *
 * Before registering the vdev, the vrings are allocated from non-cacheable
 * physically contiguous memory. Currently we only support two vrings per
 * remote processor (temporary limitation). We might also want to consider
 * doing the vring allocation only later when ->find_vqs() is invoked, and
 * then release them upon ->del_vqs().
 *
 * Note: @da is currently not really handled correctly: we dynamically
 * allocate it using the DMA API, ignoring requested hard coded addresses,
 * and we don't take care of any required IOMMU programming. This is all
 * going to be taken care of when the generic iommu-based DMA API will be
 * merged. Meanwhile, statically-addressed iommu-based firmware images should
 * use RSC_DEVMEM resource entries to map their required @da to the physical
 * address of their base CMA region (ouch, hacky!).
 *
 * Returns 0 on success, or an appropriate error code otherwise
 */
static int rproc_handle_vdev(struct rproc *rproc, struct fw_rsc_vdev *rsc,
                                                                int avail)
{
        struct device *dev = &rproc->dev;
        struct rproc_vdev *rvdev;
        int i, ret;

        /* make sure resource isn't truncated */
        if (sizeof(*rsc) + rsc->num_of_vrings * sizeof(struct fw_rsc_vdev_vring)
                        + rsc->config_len > avail) {
                dev_err(dev, "vdev rsc is truncated\n");
                return -EINVAL;
        }

        /* make sure reserved bytes are zeroes */
        if (rsc->reserved[0] || rsc->reserved[1]) {
                dev_err(dev, "vdev rsc has non zero reserved bytes\n");
                return -EINVAL;
        }

        dev_dbg(dev, "vdev rsc: id %d, dfeatures %x, cfg len %d, %d vrings\n",
                rsc->id, rsc->dfeatures, rsc->config_len, rsc->num_of_vrings);

        /* we currently support only two vrings per rvdev */
        if (rsc->num_of_vrings > ARRAY_SIZE(rvdev->vring)) {
                dev_err(dev, "too many vrings: %d\n", rsc->num_of_vrings);
                return -EINVAL;
        }

        rvdev = kzalloc(sizeof(struct rproc_vdev), GFP_KERNEL);
        if (!rvdev)
                return -ENOMEM;

        rvdev->rproc = rproc;

        /* parse the vrings */
        for (i = 0; i < rsc->num_of_vrings; i++) {
                ret = rproc_parse_vring(rvdev, rsc, i);
                if (ret)
                        goto free_rvdev;
        }

        /* remember the device features */
        rvdev->dfeatures = rsc->dfeatures;

        list_add_tail(&rvdev->node, &rproc->rvdevs);

        /* it is now safe to add the virtio device */
        ret = rproc_add_virtio_dev(rvdev, rsc->id);
        if (ret)
                goto free_rvdev;

        return 0;

free_rvdev:
        kfree(rvdev);
        return ret;
}

/**
 * rproc_handle_trace() - handle a shared trace buffer resource
 * @rproc: the remote processor
 * @rsc: the trace resource descriptor
 * @avail: size of available data (for sanity checking the image)
 *
 * In case the remote processor dumps trace logs into memory,
 * export it via debugfs.
 *
 * Currently, the 'da' member of @rsc should contain the device address
 * where the remote processor is dumping the traces. Later we could also
 * support dynamically allocating this address using the generic
 * DMA API (but currently there isn't a use case for that).
 *
 * Returns 0 on success, or an appropriate error code otherwise
 */
static int rproc_handle_trace(struct rproc *rproc, struct fw_rsc_trace *rsc,
                                                                int avail)
{
        struct rproc_mem_entry *trace;
        struct device *dev = &rproc->dev;
        void *ptr;
        char name[15];

        if (sizeof(*rsc) > avail) {
                dev_err(dev, "trace rsc is truncated\n");
                return -EINVAL;
        }

        /* make sure reserved bytes are zeroes */
        if (rsc->reserved) {
                dev_err(dev, "trace rsc has non zero reserved bytes\n");
                return -EINVAL;
        }

        /* what's the kernel address of this resource ? */
        ptr = rproc_da_to_va(rproc, rsc->da, rsc->len);
        if (!ptr) {
                dev_err(dev, "erroneous trace resource entry\n");
                return -EINVAL;
        }

        trace = kzalloc(sizeof(*trace), GFP_KERNEL);
        if (!trace) {
                dev_err(dev, "kzalloc trace failed\n");
                return -ENOMEM;
        }

        /* set the trace buffer dma properties */
        trace->len = rsc->len;
        trace->va = ptr;

        /* make sure snprintf always null terminates, even if truncating */
        snprintf(name, sizeof(name), "trace%d", rproc->num_traces);

        /* create the debugfs entry */
        trace->priv = rproc_create_trace_file(name, rproc, trace);
        if (!trace->priv) {
                trace->va = NULL;
                kfree(trace);
                return -EINVAL;
        }

        list_add_tail(&trace->node, &rproc->traces);

        rproc->num_traces++;

        dev_dbg(dev, "%s added: va %p, da 0x%x, len 0x%x\n", name, ptr,
                                                rsc->da, rsc->len);

        return 0;
}

/**
 * rproc_handle_devmem() - handle devmem resource entry
 * @rproc: remote processor handle
 * @rsc: the devmem resource entry
 * @avail: size of available data (for sanity checking the image)
 *
 * Remote processors commonly need to access certain on-chip peripherals.
 *
 * Some of these remote processors access memory via an iommu device,
 * and might require us to configure their iommu before they can access
 * the on-chip peripherals they need.
 *
 * This resource entry is a request to map such a peripheral device.
 *
 * These devmem entries will contain the physical address of the device in
 * the 'pa' member. If a specific device address is expected, then 'da' will
 * contain it (currently this is the only use case supported). 'len' will
 * contain the size of the physical region we need to map.
 *
 * Currently we just "trust" those devmem entries to contain valid physical
 * addresses, but this is going to change: we want the implementations to
 * tell us ranges of physical addresses the firmware is allowed to request,
 * and not allow firmwares to request access to physical addresses that
 * are outside those ranges.
 */
static int rproc_handle_devmem(struct rproc *rproc, struct fw_rsc_devmem *rsc,
                                                                int avail)
{
        struct rproc_mem_entry *mapping;
        struct device *dev = &rproc->dev;
        int ret;

        /* no point in handling this resource without a valid iommu domain */
        if (!rproc->domain)
                return -EINVAL;

        if (sizeof(*rsc) > avail) {
                dev_err(dev, "devmem rsc is truncated\n");
                return -EINVAL;
        }

        /* make sure reserved bytes are zeroes */
        if (rsc->reserved) {
                dev_err(dev, "devmem rsc has non zero reserved bytes\n");
                return -EINVAL;
        }

        mapping = kzalloc(sizeof(*mapping), GFP_KERNEL);
        if (!mapping) {
                dev_err(dev, "kzalloc mapping failed\n");
                return -ENOMEM;
        }

        ret = iommu_map(rproc->domain, rsc->da, rsc->pa, rsc->len, rsc->flags);
        if (ret) {
                dev_err(dev, "failed to map devmem: %d\n", ret);
                goto out;
        }

        /*
         * We'll need this info later when we'll want to unmap everything
         * (e.g. on shutdown).
         *
         * We can't trust the remote processor not to change the resource
         * table, so we must maintain this info independently.
         */
        mapping->da = rsc->da;
        mapping->len = rsc->len;
        list_add_tail(&mapping->node, &rproc->mappings);

        dev_dbg(dev, "mapped devmem pa 0x%x, da 0x%x, len 0x%x\n",
                                        rsc->pa, rsc->da, rsc->len);

        return 0;

out:
        kfree(mapping);
        return ret;
}

/**
 * rproc_handle_carveout() - handle phys contig memory allocation requests
 * @rproc: rproc handle
 * @rsc: the resource entry
 * @avail: size of available data (for image validation)
 *
 * This function will handle firmware requests for allocation of physically
 * contiguous memory regions.
 *
 * These request entries should come first in the firmware's resource table,
 * as other firmware entries might request placing other data objects inside
 * these memory regions (e.g. data/code segments, trace resource entries, ...).
 *
 * Allocating memory this way helps utilizing the reserved physical memory
 * (e.g. CMA) more efficiently, and also minimizes the number of TLB entries
 * needed to map it (in case @rproc is using an IOMMU). Reducing the TLB
 * pressure is important; it may have a substantial impact on performance.
 */
static int rproc_handle_carveout(struct rproc *rproc,
                                struct fw_rsc_carveout *rsc, int avail)
{
        struct rproc_mem_entry *carveout, *mapping;
        struct device *dev = &rproc->dev;
        dma_addr_t dma;
        void *va;
        int ret;

        if (sizeof(*rsc) > avail) {
                dev_err(dev, "carveout rsc is truncated\n");
                return -EINVAL;
        }

        /* make sure reserved bytes are zeroes */
        if (rsc->reserved) {
                dev_err(dev, "carveout rsc has non zero reserved bytes\n");
                return -EINVAL;
        }

        dev_dbg(dev, "carveout rsc: da %x, pa %x, len %x, flags %x\n",
                        rsc->da, rsc->pa, rsc->len, rsc->flags);

        carveout = kzalloc(sizeof(*carveout), GFP_KERNEL);
        if (!carveout) {
                dev_err(dev, "kzalloc carveout failed\n");
                return -ENOMEM;
        }

        va = dma_alloc_coherent(dev->parent, rsc->len, &dma, GFP_KERNEL);
        if (!va) {
                dev_err(dev->parent, "dma_alloc_coherent err: %d\n", rsc->len);
                ret = -ENOMEM;
                goto free_carv;
        }

        dev_dbg(dev, "carveout va %p, dma %x, len 0x%x\n", va, dma, rsc->len);

        /*
         * Ok, this is non-standard.
         *
         * Sometimes we can't rely on the generic iommu-based DMA API
         * to dynamically allocate the device address and then set the IOMMU
         * tables accordingly, because some remote processors might
         * _require_ us to use hard coded device addresses that their
         * firmware was compiled with.
         *
         * In this case, we must use the IOMMU API directly and map
         * the memory to the device address as expected by the remote
         * processor.
         *
         * Obviously such remote processor devices should not be configured
         * to use the iommu-based DMA API: we expect 'dma' to contain the
         * physical address in this case.
         */
        if (rproc->domain) {
                mapping = kzalloc(sizeof(*mapping), GFP_KERNEL);
                if (!mapping) {
                        dev_err(dev, "kzalloc mapping failed\n");
                        ret = -ENOMEM;
                        goto dma_free;
                }

                ret = iommu_map(rproc->domain, rsc->da, dma, rsc->len,
                                                                rsc->flags);
                if (ret) {
                        dev_err(dev, "iommu_map failed: %d\n", ret);
                        goto free_mapping;
                }

                /*
                 * We'll need this info later when we'll want to unmap
                 * everything (e.g. on shutdown).
                 *
                 * We can't trust the remote processor not to change the
                 * resource table, so we must maintain this info independently.
                 */
                mapping->da = rsc->da;
                mapping->len = rsc->len;
                list_add_tail(&mapping->node, &rproc->mappings);

                dev_dbg(dev, "carveout mapped 0x%x to 0x%x\n", rsc->da, dma);
        }

        /*
         * Some remote processors might need to know the pa
         * even though they are behind an IOMMU. E.g., OMAP4's
         * remote M3 processor needs this so it can control
         * on-chip hardware accelerators that are not behind
         * the IOMMU, and therefor must know the pa.
         *
         * Generally we don't want to expose physical addresses
         * if we don't have to (remote processors are generally
         * _not_ trusted), so we might want to do this only for
         * remote processor that _must_ have this (e.g. OMAP4's
         * dual M3 subsystem).
         *
         * Non-IOMMU processors might also want to have this info.
         * In this case, the device address and the physical address
         * are the same.
         */
        rsc->pa = dma;

        carveout->va = va;
        carveout->len = rsc->len;
        carveout->dma = dma;
        carveout->da = rsc->da;

        list_add_tail(&carveout->node, &rproc->carveouts);

        return 0;

free_mapping:
        kfree(mapping);
dma_free:
        dma_free_coherent(dev->parent, rsc->len, va, dma);
free_carv:
        kfree(carveout);
        return ret;
}

/*
 * A lookup table for resource handlers. The indices are defined in
 * enum fw_resource_type.
 */
static rproc_handle_resource_t rproc_handle_rsc[] = {
        [RSC_CARVEOUT] = (rproc_handle_resource_t)rproc_handle_carveout,
        [RSC_DEVMEM] = (rproc_handle_resource_t)rproc_handle_devmem,
        [RSC_TRACE] = (rproc_handle_resource_t)rproc_handle_trace,
        [RSC_VDEV] = NULL, /* VDEVs were handled upon registrarion */
};

/* handle firmware resource entries before booting the remote processor */
static int
rproc_handle_boot_rsc(struct rproc *rproc, struct resource_table *table, int len)
{
        struct device *dev = &rproc->dev;
        rproc_handle_resource_t handler;
        int ret = 0, i;

        for (i = 0; i < table->num; i++) {
                int offset = table->offset[i];
                struct fw_rsc_hdr *hdr = (void *)table + offset;
                int avail = len - offset - sizeof(*hdr);
                void *rsc = (void *)hdr + sizeof(*hdr);

                /* make sure table isn't truncated */
                if (avail < 0) {
                        dev_err(dev, "rsc table is truncated\n");
                        return -EINVAL;
                }

                dev_dbg(dev, "rsc: type %d\n", hdr->type);

                if (hdr->type >= RSC_LAST) {
                        dev_warn(dev, "unsupported resource %d\n", hdr->type);
                        continue;
                }

                handler = rproc_handle_rsc[hdr->type];
                if (!handler)
                        continue;

                ret = handler(rproc, rsc, avail);
                if (ret)
                        break;
        }

        return ret;
}

/* handle firmware resource entries while registering the remote processor */
static int
rproc_handle_virtio_rsc(struct rproc *rproc, struct resource_table *table, int len)
{
        struct device *dev = &rproc->dev;
        int ret = 0, i;

        for (i = 0; i < table->num; i++) {
                int offset = table->offset[i];
                struct fw_rsc_hdr *hdr = (void *)table + offset;
                int avail = len - offset - sizeof(*hdr);
                struct fw_rsc_vdev *vrsc;

                /* make sure table isn't truncated */
                if (avail < 0) {
                        dev_err(dev, "rsc table is truncated\n");
                        return -EINVAL;
                }

                dev_dbg(dev, "%s: rsc type %d\n", __func__, hdr->type);

                if (hdr->type != RSC_VDEV)
                        continue;

                vrsc = (struct fw_rsc_vdev *)hdr->data;

                ret = rproc_handle_vdev(rproc, vrsc, avail);
                if (ret)
                        break;
        }

        return ret;
}

/**
 * rproc_resource_cleanup() - clean up and free all acquired resources
 * @rproc: rproc handle
 *
 * This function will free all resources acquired for @rproc, and it
 * is called whenever @rproc either shuts down or fails to boot.
 */
static void rproc_resource_cleanup(struct rproc *rproc)
{
        struct rproc_mem_entry *entry, *tmp;
        struct device *dev = &rproc->dev;

        /* clean up debugfs trace entries */
        list_for_each_entry_safe(entry, tmp, &rproc->traces, node) {
                rproc_remove_trace_file(entry->priv);
                rproc->num_traces--;
                list_del(&entry->node);
                kfree(entry);
        }

        /* clean up carveout allocations */
        list_for_each_entry_safe(entry, tmp, &rproc->carveouts, node) {
                dma_free_coherent(dev->parent, entry->len, entry->va, entry->dma);
                list_del(&entry->node);
                kfree(entry);
        }

        /* clean up iommu mapping entries */
        list_for_each_entry_safe(entry, tmp, &rproc->mappings, node) {
                size_t unmapped;

                unmapped = iommu_unmap(rproc->domain, entry->da, entry->len);
                if (unmapped != entry->len) {
                        /* nothing much to do besides complaining */
                        dev_err(dev, "failed to unmap %u/%zu\n", entry->len,
                                                                unmapped);
                }

                list_del(&entry->node);
                kfree(entry);
        }
}

/*
 * take a firmware and boot a remote processor with it.
 */
static int rproc_fw_boot(struct rproc *rproc, const struct firmware *fw)
{
        struct device *dev = &rproc->dev;
        const char *name = rproc->firmware;
        struct resource_table *table;
        int ret, tablesz;

        ret = rproc_fw_sanity_check(rproc, fw);
        if (ret)
                return ret;

        dev_info(dev, "Booting fw image %s, size %zd\n", name, fw->size);

        /*
         * if enabling an IOMMU isn't relevant for this rproc, this is
         * just a nop
         */
        ret = rproc_enable_iommu(rproc);
        if (ret) {
                dev_err(dev, "can't enable iommu: %d\n", ret);
                return ret;
        }

        rproc->bootaddr = rproc_get_boot_addr(rproc, fw);

        /* look for the resource table */
        table = rproc_find_rsc_table(rproc, fw, &tablesz);
        if (!table) {
                ret = -EINVAL;
                goto clean_up;
        }

        /* handle fw resources which are required to boot rproc */
        ret = rproc_handle_boot_rsc(rproc, table, tablesz);
        if (ret) {
                dev_err(dev, "Failed to process resources: %d\n", ret);
                goto clean_up;
        }

        /* load the ELF segments to memory */
        ret = rproc_load_segments(rproc, fw);
        if (ret) {
                dev_err(dev, "Failed to load program segments: %d\n", ret);
                goto clean_up;
        }

        /* power up the remote processor */
        ret = rproc->ops->start(rproc);
        if (ret) {
                dev_err(dev, "can't start rproc %s: %d\n", rproc->name, ret);
                goto clean_up;
        }

        rproc->state = RPROC_RUNNING;

        dev_info(dev, "remote processor %s is now up\n", rproc->name);

        return 0;

clean_up:
        rproc_resource_cleanup(rproc);
        rproc_disable_iommu(rproc);
        return ret;
}

/*
 * take a firmware and look for virtio devices to register.
 *
 * Note: this function is called asynchronously upon registration of the
 * remote processor (so we must wait until it completes before we try
 * to unregister the device. one other option is just to use kref here,
 * that might be cleaner).
 */
static void rproc_fw_config_virtio(const struct firmware *fw, void *context)
{
        struct rproc *rproc = context;
        struct resource_table *table;
        int ret, tablesz;

        if (rproc_fw_sanity_check(rproc, fw) < 0)
                goto out;

        /* look for the resource table */
        table = rproc_find_rsc_table(rproc, fw,  &tablesz);
        if (!table)
                goto out;

        /* look for virtio devices and register them */
        ret = rproc_handle_virtio_rsc(rproc, table, tablesz);
        if (ret)
                goto out;

out:
        release_firmware(fw);
        /* allow rproc_del() contexts, if any, to proceed */
        complete_all(&rproc->firmware_loading_complete);
}

/**
 * rproc_boot() - boot a remote processor
 * @rproc: handle of a remote processor
 *
 * Boot a remote processor (i.e. load its firmware, power it on, ...).
 *
 * If the remote processor is already powered on, this function immediately
 * returns (successfully).
 *
 * Returns 0 on success, and an appropriate error value otherwise.
 */
int rproc_boot(struct rproc *rproc)
{
        const struct firmware *firmware_p;
        struct device *dev;
        int ret;

        if (!rproc) {
                pr_err("invalid rproc handle\n");
                return -EINVAL;
        }

        dev = &rproc->dev;

        ret = mutex_lock_interruptible(&rproc->lock);
        if (ret) {
                dev_err(dev, "can't lock rproc %s: %d\n", rproc->name, ret);
                return ret;
        }

        /* loading a firmware is required */
        if (!rproc->firmware) {
                dev_err(dev, "%s: no firmware to load\n", __func__);
                ret = -EINVAL;
                goto unlock_mutex;
        }

        /* prevent underlying implementation from being removed */
        if (!try_module_get(dev->parent->driver->owner)) {
                dev_err(dev, "%s: can't get owner\n", __func__);
                ret = -EINVAL;
                goto unlock_mutex;
        }

        /* skip the boot process if rproc is already powered up */
        if (atomic_inc_return(&rproc->power) > 1) {
                ret = 0;
                goto unlock_mutex;
        }

        dev_info(dev, "powering up %s\n", rproc->name);

        /* load firmware */
        ret = request_firmware(&firmware_p, rproc->firmware, dev);
        if (ret < 0) {
                dev_err(dev, "request_firmware failed: %d\n", ret);
                goto downref_rproc;
        }

        ret = rproc_fw_boot(rproc, firmware_p);

        release_firmware(firmware_p);

downref_rproc:
        if (ret) {
                module_put(dev->parent->driver->owner);
                atomic_dec(&rproc->power);
        }
unlock_mutex:
        mutex_unlock(&rproc->lock);
        return ret;
}
EXPORT_SYMBOL(rproc_boot);

/**
 * rproc_shutdown() - power off the remote processor
 * @rproc: the remote processor
 *
 * Power off a remote processor (previously booted with rproc_boot()).
 *
 * In case @rproc is still being used by an additional user(s), then
 * this function will just decrement the power refcount and exit,
 * without really powering off the device.
 *
 * Every call to rproc_boot() must (eventually) be accompanied by a call
 * to rproc_shutdown(). Calling rproc_shutdown() redundantly is a bug.
 *
 * Notes:
 * - we're not decrementing the rproc's refcount, only the power refcount.
 *   which means that the @rproc handle stays valid even after rproc_shutdown()
 *   returns, and users can still use it with a subsequent rproc_boot(), if
 *   needed.
 */
void rproc_shutdown(struct rproc *rproc)
{
        struct device *dev = &rproc->dev;
        int ret;

        ret = mutex_lock_interruptible(&rproc->lock);
        if (ret) {
                dev_err(dev, "can't lock rproc %s: %d\n", rproc->name, ret);
                return;
        }

        /* if the remote proc is still needed, bail out */
        if (!atomic_dec_and_test(&rproc->power))
                goto out;

        /* power off the remote processor */
        ret = rproc->ops->stop(rproc);
        if (ret) {
                atomic_inc(&rproc->power);
                dev_err(dev, "can't stop rproc: %d\n", ret);
                goto out;
        }

        /* clean up all acquired resources */
        rproc_resource_cleanup(rproc);

        rproc_disable_iommu(rproc);

        rproc->state = RPROC_OFFLINE;

        dev_info(dev, "stopped remote processor %s\n", rproc->name);

out:
        mutex_unlock(&rproc->lock);

        if (!ret)
                module_put(dev->parent->driver->owner);
}
EXPORT_SYMBOL(rproc_shutdown);

/**
 * rproc_add() - register a remote processor
 * @rproc: the remote processor handle to register
 *
 * Registers @rproc with the remoteproc framework, after it has been
 * allocated with rproc_alloc().
 *
 * This is called by the platform-specific rproc implementation, whenever
 * a new remote processor device is probed.
 *
 * Returns 0 on success and an appropriate error code otherwise.
 *
 * Note: this function initiates an asynchronous firmware loading
 * context, which will look for virtio devices supported by the rproc's
 * firmware.
 *
 * If found, those virtio devices will be created and added, so as a result
 * of registering this remote processor, additional virtio drivers might be
 * probed.
 */
int rproc_add(struct rproc *rproc)
{
        struct device *dev = &rproc->dev;
        int ret = 0;

        ret = device_add(dev);
        if (ret < 0)
                return ret;

        dev_info(dev, "%s is available\n", rproc->name);

        dev_info(dev, "Note: remoteproc is still under development and considered experimental.\n");
        dev_info(dev, "THE BINARY FORMAT IS NOT YET FINALIZED, and backward compatibility isn't yet guaranteed.\n");

        /* create debugfs entries */
        rproc_create_debug_dir(rproc);

        /* rproc_del() calls must wait until async loader completes */
        init_completion(&rproc->firmware_loading_complete);

        /*
         * We must retrieve early virtio configuration info from
         * the firmware (e.g. whether to register a virtio device,
         * what virtio features does it support, ...).
         *
         * We're initiating an asynchronous firmware loading, so we can
         * be built-in kernel code, without hanging the boot process.
         */
        ret = request_firmware_nowait(THIS_MODULE, FW_ACTION_HOTPLUG,
                                        rproc->firmware, dev, GFP_KERNEL,
                                        rproc, rproc_fw_config_virtio);
        if (ret < 0) {
                dev_err(dev, "request_firmware_nowait failed: %d\n", ret);
                complete_all(&rproc->firmware_loading_complete);
        }

        return ret;
}
EXPORT_SYMBOL(rproc_add);

/**
 * rproc_type_release() - release a remote processor instance
 * @dev: the rproc's device
 *
 * This function should _never_ be called directly.
 *
 * It will be called by the driver core when no one holds a valid pointer
 * to @dev anymore.
 */
static void rproc_type_release(struct device *dev)
{
        struct rproc *rproc = container_of(dev, struct rproc, dev);

        dev_info(&rproc->dev, "releasing %s\n", rproc->name);

        rproc_delete_debug_dir(rproc);

        idr_remove_all(&rproc->notifyids);
        idr_destroy(&rproc->notifyids);

        if (rproc->index >= 0)
                ida_simple_remove(&rproc_dev_index, rproc->index);

        kfree(rproc);
}

static struct device_type rproc_type = {
        .name           = "remoteproc",
        .release        = rproc_type_release,
};

/**
 * rproc_alloc() - allocate a remote processor handle
 * @dev: the underlying device
 * @name: name of this remote processor
 * @ops: platform-specific handlers (mainly start/stop)
 * @firmware: name of firmware file to load
 * @len: length of private data needed by the rproc driver (in bytes)
 *
 * Allocates a new remote processor handle, but does not register
 * it yet.
 *
 * This function should be used by rproc implementations during initialization
 * of the remote processor.
 *
 * After creating an rproc handle using this function, and when ready,
 * implementations should then call rproc_add() to complete
 * the registration of the remote processor.
 *
 * On success the new rproc is returned, and on failure, NULL.
 *
 * Note: _never_ directly deallocate @rproc, even if it was not registered
 * yet. Instead, when you need to unroll rproc_alloc(), use rproc_put().
 */
struct rproc *rproc_alloc(struct device *dev, const char *name,
                                const struct rproc_ops *ops,
                                const char *firmware, int len)
{
        struct rproc *rproc;

        if (!dev || !name || !ops)
                return NULL;

        rproc = kzalloc(sizeof(struct rproc) + len, GFP_KERNEL);
        if (!rproc) {
                dev_err(dev, "%s: kzalloc failed\n", __func__);
                return NULL;
        }

        rproc->name = name;
        rproc->ops = ops;
        rproc->firmware = firmware;
        rproc->priv = &rproc[1];

        device_initialize(&rproc->dev);
        rproc->dev.parent = dev;
        rproc->dev.type = &rproc_type;

        /* Assign a unique device index and name */
        rproc->index = ida_simple_get(&rproc_dev_index, 0, 0, GFP_KERNEL);
        if (rproc->index < 0) {
                dev_err(dev, "ida_simple_get failed: %d\n", rproc->index);
                put_device(&rproc->dev);
                return NULL;
        }

        dev_set_name(&rproc->dev, "remoteproc%d", rproc->index);

        atomic_set(&rproc->power, 0);

        /* Set ELF as the default fw_ops handler */
        rproc->fw_ops = &rproc_elf_fw_ops;

        mutex_init(&rproc->lock);

        idr_init(&rproc->notifyids);

        INIT_LIST_HEAD(&rproc->carveouts);
        INIT_LIST_HEAD(&rproc->mappings);
        INIT_LIST_HEAD(&rproc->traces);
        INIT_LIST_HEAD(&rproc->rvdevs);

        rproc->state = RPROC_OFFLINE;

        return rproc;
}
EXPORT_SYMBOL(rproc_alloc);

/**
 * rproc_put() - unroll rproc_alloc()
 * @rproc: the remote processor handle
 *
 * This function decrements the rproc dev refcount.
 *
 * If no one holds any reference to rproc anymore, then its refcount would
 * now drop to zero, and it would be freed.
 */
void rproc_put(struct rproc *rproc)
{
        put_device(&rproc->dev);
}
EXPORT_SYMBOL(rproc_put);

/**
 * rproc_del() - unregister a remote processor
 * @rproc: rproc handle to unregister
 *
 * This function should be called when the platform specific rproc
 * implementation decides to remove the rproc device. it should
 * _only_ be called if a previous invocation of rproc_add()
 * has completed successfully.
 *
 * After rproc_del() returns, @rproc isn't freed yet, because
 * of the outstanding reference created by rproc_alloc. To decrement that
 * one last refcount, one still needs to call rproc_put().
 *
 * Returns 0 on success and -EINVAL if @rproc isn't valid.
 */
int rproc_del(struct rproc *rproc)
{
        struct rproc_vdev *rvdev, *tmp;

        if (!rproc)
                return -EINVAL;

        /* if rproc is just being registered, wait */
        wait_for_completion(&rproc->firmware_loading_complete);

        /* clean up remote vdev entries */
        list_for_each_entry_safe(rvdev, tmp, &rproc->rvdevs, node)
                rproc_remove_virtio_dev(rvdev);

        device_del(&rproc->dev);

        return 0;
}
EXPORT_SYMBOL(rproc_del);

static int __init remoteproc_init(void)
{
        rproc_init_debugfs();

        return 0;
}
module_init(remoteproc_init);

static void __exit remoteproc_exit(void)
{
        rproc_exit_debugfs();
}
module_exit(remoteproc_exit);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Generic Remote Processor Framework");