Linux 5.1.15

[linux/fpc-iii.git] / drivers / base / firmware_loader / main.c

// SPDX-License-Identifier: GPL-2.0
/*
 * main.c - Multi purpose firmware loading support
 *
 * Copyright (c) 2003 Manuel Estrada Sainz
 *
 * Please see Documentation/firmware_class/ for more information.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/capability.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/timer.h>
#include <linux/vmalloc.h>
#include <linux/interrupt.h>
#include <linux/bitops.h>
#include <linux/mutex.h>
#include <linux/workqueue.h>
#include <linux/highmem.h>
#include <linux/firmware.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/file.h>
#include <linux/list.h>
#include <linux/fs.h>
#include <linux/async.h>
#include <linux/pm.h>
#include <linux/suspend.h>
#include <linux/syscore_ops.h>
#include <linux/reboot.h>
#include <linux/security.h>

#include <generated/utsrelease.h>

#include "../base.h"
#include "firmware.h"
#include "fallback.h"

MODULE_AUTHOR("Manuel Estrada Sainz");
MODULE_DESCRIPTION("Multi purpose firmware loading support");
MODULE_LICENSE("GPL");

struct firmware_cache {
        /* firmware_buf instance will be added into the below list */
        spinlock_t lock;
        struct list_head head;
        int state;

#ifdef CONFIG_PM_SLEEP
        /*
         * Names of firmware images which have been cached successfully
         * will be added into the below list so that device uncache
         * helper can trace which firmware images have been cached
         * before.
         */
        spinlock_t name_lock;
        struct list_head fw_names;

        struct delayed_work work;

        struct notifier_block   pm_notify;
#endif
};

struct fw_cache_entry {
        struct list_head list;
        const char *name;
};

struct fw_name_devm {
        unsigned long magic;
        const char *name;
};

static inline struct fw_priv *to_fw_priv(struct kref *ref)
{
        return container_of(ref, struct fw_priv, ref);
}

#define FW_LOADER_NO_CACHE      0
#define FW_LOADER_START_CACHE   1

/* fw_lock could be moved to 'struct fw_sysfs' but since it is just
 * guarding for corner cases a global lock should be OK */
DEFINE_MUTEX(fw_lock);

static struct firmware_cache fw_cache;

/* Builtin firmware support */

#ifdef CONFIG_FW_LOADER

extern struct builtin_fw __start_builtin_fw[];
extern struct builtin_fw __end_builtin_fw[];

static void fw_copy_to_prealloc_buf(struct firmware *fw,
                                    void *buf, size_t size)
{
        if (!buf || size < fw->size)
                return;
        memcpy(buf, fw->data, fw->size);
}

static bool fw_get_builtin_firmware(struct firmware *fw, const char *name,
                                    void *buf, size_t size)
{
        struct builtin_fw *b_fw;

        for (b_fw = __start_builtin_fw; b_fw != __end_builtin_fw; b_fw++) {
                if (strcmp(name, b_fw->name) == 0) {
                        fw->size = b_fw->size;
                        fw->data = b_fw->data;
                        fw_copy_to_prealloc_buf(fw, buf, size);

                        return true;
                }
        }

        return false;
}

static bool fw_is_builtin_firmware(const struct firmware *fw)
{
        struct builtin_fw *b_fw;

        for (b_fw = __start_builtin_fw; b_fw != __end_builtin_fw; b_fw++)
                if (fw->data == b_fw->data)
                        return true;

        return false;
}

#else /* Module case - no builtin firmware support */

static inline bool fw_get_builtin_firmware(struct firmware *fw,
                                           const char *name, void *buf,
                                           size_t size)
{
        return false;
}

static inline bool fw_is_builtin_firmware(const struct firmware *fw)
{
        return false;
}
#endif

static void fw_state_init(struct fw_priv *fw_priv)
{
        struct fw_state *fw_st = &fw_priv->fw_st;

        init_completion(&fw_st->completion);
        fw_st->status = FW_STATUS_UNKNOWN;
}

static inline int fw_state_wait(struct fw_priv *fw_priv)
{
        return __fw_state_wait_common(fw_priv, MAX_SCHEDULE_TIMEOUT);
}

static int fw_cache_piggyback_on_request(const char *name);

static struct fw_priv *__allocate_fw_priv(const char *fw_name,
                                          struct firmware_cache *fwc,
                                          void *dbuf, size_t size)
{
        struct fw_priv *fw_priv;

        fw_priv = kzalloc(sizeof(*fw_priv), GFP_ATOMIC);
        if (!fw_priv)
                return NULL;

        fw_priv->fw_name = kstrdup_const(fw_name, GFP_ATOMIC);
        if (!fw_priv->fw_name) {
                kfree(fw_priv);
                return NULL;
        }

        kref_init(&fw_priv->ref);
        fw_priv->fwc = fwc;
        fw_priv->data = dbuf;
        fw_priv->allocated_size = size;
        fw_state_init(fw_priv);
#ifdef CONFIG_FW_LOADER_USER_HELPER
        INIT_LIST_HEAD(&fw_priv->pending_list);
#endif

        pr_debug("%s: fw-%s fw_priv=%p\n", __func__, fw_name, fw_priv);

        return fw_priv;
}

static struct fw_priv *__lookup_fw_priv(const char *fw_name)
{
        struct fw_priv *tmp;
        struct firmware_cache *fwc = &fw_cache;

        list_for_each_entry(tmp, &fwc->head, list)
                if (!strcmp(tmp->fw_name, fw_name))
                        return tmp;
        return NULL;
}

/* Returns 1 for batching firmware requests with the same name */
static int alloc_lookup_fw_priv(const char *fw_name,
                                struct firmware_cache *fwc,
                                struct fw_priv **fw_priv, void *dbuf,
                                size_t size, enum fw_opt opt_flags)
{
        struct fw_priv *tmp;

        spin_lock(&fwc->lock);
        if (!(opt_flags & FW_OPT_NOCACHE)) {
                tmp = __lookup_fw_priv(fw_name);
                if (tmp) {
                        kref_get(&tmp->ref);
                        spin_unlock(&fwc->lock);
                        *fw_priv = tmp;
                        pr_debug("batched request - sharing the same struct fw_priv and lookup for multiple requests\n");
                        return 1;
                }
        }

        tmp = __allocate_fw_priv(fw_name, fwc, dbuf, size);
        if (tmp) {
                INIT_LIST_HEAD(&tmp->list);
                if (!(opt_flags & FW_OPT_NOCACHE))
                        list_add(&tmp->list, &fwc->head);
        }
        spin_unlock(&fwc->lock);

        *fw_priv = tmp;

        return tmp ? 0 : -ENOMEM;
}

static void __free_fw_priv(struct kref *ref)
        __releases(&fwc->lock)
{
        struct fw_priv *fw_priv = to_fw_priv(ref);
        struct firmware_cache *fwc = fw_priv->fwc;

        pr_debug("%s: fw-%s fw_priv=%p data=%p size=%u\n",
                 __func__, fw_priv->fw_name, fw_priv, fw_priv->data,
                 (unsigned int)fw_priv->size);

        list_del(&fw_priv->list);
        spin_unlock(&fwc->lock);

#ifdef CONFIG_FW_LOADER_USER_HELPER
        if (fw_priv->is_paged_buf) {
                int i;
                vunmap(fw_priv->data);
                for (i = 0; i < fw_priv->nr_pages; i++)
                        __free_page(fw_priv->pages[i]);
                vfree(fw_priv->pages);
        } else
#endif
        if (!fw_priv->allocated_size)
                vfree(fw_priv->data);
        kfree_const(fw_priv->fw_name);
        kfree(fw_priv);
}

static void free_fw_priv(struct fw_priv *fw_priv)
{
        struct firmware_cache *fwc = fw_priv->fwc;
        spin_lock(&fwc->lock);
        if (!kref_put(&fw_priv->ref, __free_fw_priv))
                spin_unlock(&fwc->lock);
}

/* direct firmware loading support */
static char fw_path_para[256];
static const char * const fw_path[] = {
        fw_path_para,
        "/lib/firmware/updates/" UTS_RELEASE,
        "/lib/firmware/updates",
        "/lib/firmware/" UTS_RELEASE,
        "/lib/firmware"
};

/*
 * Typical usage is that passing 'firmware_class.path=$CUSTOMIZED_PATH'
 * from kernel command line because firmware_class is generally built in
 * kernel instead of module.
 */
module_param_string(path, fw_path_para, sizeof(fw_path_para), 0644);
MODULE_PARM_DESC(path, "customized firmware image search path with a higher priority than default path");

static int
fw_get_filesystem_firmware(struct device *device, struct fw_priv *fw_priv)
{
        loff_t size;
        int i, len;
        int rc = -ENOENT;
        char *path;
        enum kernel_read_file_id id = READING_FIRMWARE;
        size_t msize = INT_MAX;

        /* Already populated data member means we're loading into a buffer */
        if (fw_priv->data) {
                id = READING_FIRMWARE_PREALLOC_BUFFER;
                msize = fw_priv->allocated_size;
        }

        path = __getname();
        if (!path)
                return -ENOMEM;

        for (i = 0; i < ARRAY_SIZE(fw_path); i++) {
                /* skip the unset customized path */
                if (!fw_path[i][0])
                        continue;

                len = snprintf(path, PATH_MAX, "%s/%s",
                               fw_path[i], fw_priv->fw_name);
                if (len >= PATH_MAX) {
                        rc = -ENAMETOOLONG;
                        break;
                }

                fw_priv->size = 0;
                rc = kernel_read_file_from_path(path, &fw_priv->data, &size,
                                                msize, id);
                if (rc) {
                        if (rc != -ENOENT)
                                dev_warn(device, "loading %s failed with error %d\n",
                                         path, rc);
                        else
                                dev_dbg(device, "loading %s failed for no such file or directory.\n",
                                         path);
                        continue;
                }
                dev_dbg(device, "direct-loading %s\n", fw_priv->fw_name);
                fw_priv->size = size;
                fw_state_done(fw_priv);
                break;
        }
        __putname(path);

        return rc;
}

/* firmware holds the ownership of pages */
static void firmware_free_data(const struct firmware *fw)
{
        /* Loaded directly? */
        if (!fw->priv) {
                vfree(fw->data);
                return;
        }
        free_fw_priv(fw->priv);
}

/* store the pages buffer info firmware from buf */
static void fw_set_page_data(struct fw_priv *fw_priv, struct firmware *fw)
{
        fw->priv = fw_priv;
#ifdef CONFIG_FW_LOADER_USER_HELPER
        fw->pages = fw_priv->pages;
#endif
        fw->size = fw_priv->size;
        fw->data = fw_priv->data;

        pr_debug("%s: fw-%s fw_priv=%p data=%p size=%u\n",
                 __func__, fw_priv->fw_name, fw_priv, fw_priv->data,
                 (unsigned int)fw_priv->size);
}

#ifdef CONFIG_PM_SLEEP
static void fw_name_devm_release(struct device *dev, void *res)
{
        struct fw_name_devm *fwn = res;

        if (fwn->magic == (unsigned long)&fw_cache)
                pr_debug("%s: fw_name-%s devm-%p released\n",
                                __func__, fwn->name, res);
        kfree_const(fwn->name);
}

static int fw_devm_match(struct device *dev, void *res,
                void *match_data)
{
        struct fw_name_devm *fwn = res;

        return (fwn->magic == (unsigned long)&fw_cache) &&
                !strcmp(fwn->name, match_data);
}

static struct fw_name_devm *fw_find_devm_name(struct device *dev,
                const char *name)
{
        struct fw_name_devm *fwn;

        fwn = devres_find(dev, fw_name_devm_release,
                          fw_devm_match, (void *)name);
        return fwn;
}

static bool fw_cache_is_setup(struct device *dev, const char *name)
{
        struct fw_name_devm *fwn;

        fwn = fw_find_devm_name(dev, name);
        if (fwn)
                return true;

        return false;
}

/* add firmware name into devres list */
static int fw_add_devm_name(struct device *dev, const char *name)
{
        struct fw_name_devm *fwn;

        if (fw_cache_is_setup(dev, name))
                return 0;

        fwn = devres_alloc(fw_name_devm_release, sizeof(struct fw_name_devm),
                           GFP_KERNEL);
        if (!fwn)
                return -ENOMEM;
        fwn->name = kstrdup_const(name, GFP_KERNEL);
        if (!fwn->name) {
                devres_free(fwn);
                return -ENOMEM;
        }

        fwn->magic = (unsigned long)&fw_cache;
        devres_add(dev, fwn);

        return 0;
}
#else
static bool fw_cache_is_setup(struct device *dev, const char *name)
{
        return false;
}

static int fw_add_devm_name(struct device *dev, const char *name)
{
        return 0;
}
#endif

int assign_fw(struct firmware *fw, struct device *device,
              enum fw_opt opt_flags)
{
        struct fw_priv *fw_priv = fw->priv;
        int ret;

        mutex_lock(&fw_lock);
        if (!fw_priv->size || fw_state_is_aborted(fw_priv)) {
                mutex_unlock(&fw_lock);
                return -ENOENT;
        }

        /*
         * add firmware name into devres list so that we can auto cache
         * and uncache firmware for device.
         *
         * device may has been deleted already, but the problem
         * should be fixed in devres or driver core.
         */
        /* don't cache firmware handled without uevent */
        if (device && (opt_flags & FW_OPT_UEVENT) &&
            !(opt_flags & FW_OPT_NOCACHE)) {
                ret = fw_add_devm_name(device, fw_priv->fw_name);
                if (ret) {
                        mutex_unlock(&fw_lock);
                        return ret;
                }
        }

        /*
         * After caching firmware image is started, let it piggyback
         * on request firmware.
         */
        if (!(opt_flags & FW_OPT_NOCACHE) &&
            fw_priv->fwc->state == FW_LOADER_START_CACHE) {
                if (fw_cache_piggyback_on_request(fw_priv->fw_name))
                        kref_get(&fw_priv->ref);
        }

        /* pass the pages buffer to driver at the last minute */
        fw_set_page_data(fw_priv, fw);
        mutex_unlock(&fw_lock);
        return 0;
}

/* prepare firmware and firmware_buf structs;
 * return 0 if a firmware is already assigned, 1 if need to load one,
 * or a negative error code
 */
static int
_request_firmware_prepare(struct firmware **firmware_p, const char *name,
                          struct device *device, void *dbuf, size_t size,
                          enum fw_opt opt_flags)
{
        struct firmware *firmware;
        struct fw_priv *fw_priv;
        int ret;

        *firmware_p = firmware = kzalloc(sizeof(*firmware), GFP_KERNEL);
        if (!firmware) {
                dev_err(device, "%s: kmalloc(struct firmware) failed\n",
                        __func__);
                return -ENOMEM;
        }

        if (fw_get_builtin_firmware(firmware, name, dbuf, size)) {
                dev_dbg(device, "using built-in %s\n", name);
                return 0; /* assigned */
        }

        ret = alloc_lookup_fw_priv(name, &fw_cache, &fw_priv, dbuf, size,
                                  opt_flags);

        /*
         * bind with 'priv' now to avoid warning in failure path
         * of requesting firmware.
         */
        firmware->priv = fw_priv;

        if (ret > 0) {
                ret = fw_state_wait(fw_priv);
                if (!ret) {
                        fw_set_page_data(fw_priv, firmware);
                        return 0; /* assigned */
                }
        }

        if (ret < 0)
                return ret;
        return 1; /* need to load */
}

/*
 * Batched requests need only one wake, we need to do this step last due to the
 * fallback mechanism. The buf is protected with kref_get(), and it won't be
 * released until the last user calls release_firmware().
 *
 * Failed batched requests are possible as well, in such cases we just share
 * the struct fw_priv and won't release it until all requests are woken
 * and have gone through this same path.
 */
static void fw_abort_batch_reqs(struct firmware *fw)
{
        struct fw_priv *fw_priv;

        /* Loaded directly? */
        if (!fw || !fw->priv)
                return;

        fw_priv = fw->priv;
        if (!fw_state_is_aborted(fw_priv))
                fw_state_aborted(fw_priv);
}

/* called from request_firmware() and request_firmware_work_func() */
static int
_request_firmware(const struct firmware **firmware_p, const char *name,
                  struct device *device, void *buf, size_t size,
                  enum fw_opt opt_flags)
{
        struct firmware *fw = NULL;
        int ret;

        if (!firmware_p)
                return -EINVAL;

        if (!name || name[0] == '\0') {
                ret = -EINVAL;
                goto out;
        }

        ret = _request_firmware_prepare(&fw, name, device, buf, size,
                                        opt_flags);
        if (ret <= 0) /* error or already assigned */
                goto out;

        ret = fw_get_filesystem_firmware(device, fw->priv);
        if (ret) {
                if (!(opt_flags & FW_OPT_NO_WARN))
                        dev_warn(device,
                                 "Direct firmware load for %s failed with error %d\n",
                                 name, ret);
                ret = firmware_fallback_sysfs(fw, name, device, opt_flags, ret);
        } else
                ret = assign_fw(fw, device, opt_flags);

 out:
        if (ret < 0) {
                fw_abort_batch_reqs(fw);
                release_firmware(fw);
                fw = NULL;
        }

        *firmware_p = fw;
        return ret;
}

/**
 * request_firmware() - send firmware request and wait for it
 * @firmware_p: pointer to firmware image
 * @name: name of firmware file
 * @device: device for which firmware is being loaded
 *
 *      @firmware_p will be used to return a firmware image by the name
 *      of @name for device @device.
 *
 *      Should be called from user context where sleeping is allowed.
 *
 *      @name will be used as $FIRMWARE in the uevent environment and
 *      should be distinctive enough not to be confused with any other
 *      firmware image for this or any other device.
 *
 *      Caller must hold the reference count of @device.
 *
 *      The function can be called safely inside device's suspend and
 *      resume callback.
 **/
int
request_firmware(const struct firmware **firmware_p, const char *name,
                 struct device *device)
{
        int ret;

        /* Need to pin this module until return */
        __module_get(THIS_MODULE);
        ret = _request_firmware(firmware_p, name, device, NULL, 0,
                                FW_OPT_UEVENT);
        module_put(THIS_MODULE);
        return ret;
}
EXPORT_SYMBOL(request_firmware);

/**
 * firmware_request_nowarn() - request for an optional fw module
 * @firmware: pointer to firmware image
 * @name: name of firmware file
 * @device: device for which firmware is being loaded
 *
 * This function is similar in behaviour to request_firmware(), except
 * it doesn't produce warning messages when the file is not found.
 * The sysfs fallback mechanism is enabled if direct filesystem lookup fails,
 * however, however failures to find the firmware file with it are still
 * suppressed. It is therefore up to the driver to check for the return value
 * of this call and to decide when to inform the users of errors.
 **/
int firmware_request_nowarn(const struct firmware **firmware, const char *name,
                            struct device *device)
{
        int ret;

        /* Need to pin this module until return */
        __module_get(THIS_MODULE);
        ret = _request_firmware(firmware, name, device, NULL, 0,
                                FW_OPT_UEVENT | FW_OPT_NO_WARN);
        module_put(THIS_MODULE);
        return ret;
}
EXPORT_SYMBOL_GPL(firmware_request_nowarn);

/**
 * request_firmware_direct() - load firmware directly without usermode helper
 * @firmware_p: pointer to firmware image
 * @name: name of firmware file
 * @device: device for which firmware is being loaded
 *
 * This function works pretty much like request_firmware(), but this doesn't
 * fall back to usermode helper even if the firmware couldn't be loaded
 * directly from fs.  Hence it's useful for loading optional firmwares, which
 * aren't always present, without extra long timeouts of udev.
 **/
int request_firmware_direct(const struct firmware **firmware_p,
                            const char *name, struct device *device)
{
        int ret;

        __module_get(THIS_MODULE);
        ret = _request_firmware(firmware_p, name, device, NULL, 0,
                                FW_OPT_UEVENT | FW_OPT_NO_WARN |
                                FW_OPT_NOFALLBACK);
        module_put(THIS_MODULE);
        return ret;
}
EXPORT_SYMBOL_GPL(request_firmware_direct);

/**
 * firmware_request_cache() - cache firmware for suspend so resume can use it
 * @name: name of firmware file
 * @device: device for which firmware should be cached for
 *
 * There are some devices with an optimization that enables the device to not
 * require loading firmware on system reboot. This optimization may still
 * require the firmware present on resume from suspend. This routine can be
 * used to ensure the firmware is present on resume from suspend in these
 * situations. This helper is not compatible with drivers which use
 * request_firmware_into_buf() or request_firmware_nowait() with no uevent set.
 **/
int firmware_request_cache(struct device *device, const char *name)
{
        int ret;

        mutex_lock(&fw_lock);
        ret = fw_add_devm_name(device, name);
        mutex_unlock(&fw_lock);

        return ret;
}
EXPORT_SYMBOL_GPL(firmware_request_cache);

/**
 * request_firmware_into_buf() - load firmware into a previously allocated buffer
 * @firmware_p: pointer to firmware image
 * @name: name of firmware file
 * @device: device for which firmware is being loaded and DMA region allocated
 * @buf: address of buffer to load firmware into
 * @size: size of buffer
 *
 * This function works pretty much like request_firmware(), but it doesn't
 * allocate a buffer to hold the firmware data. Instead, the firmware
 * is loaded directly into the buffer pointed to by @buf and the @firmware_p
 * data member is pointed at @buf.
 *
 * This function doesn't cache firmware either.
 */
int
request_firmware_into_buf(const struct firmware **firmware_p, const char *name,
                          struct device *device, void *buf, size_t size)
{
        int ret;

        if (fw_cache_is_setup(device, name))
                return -EOPNOTSUPP;

        __module_get(THIS_MODULE);
        ret = _request_firmware(firmware_p, name, device, buf, size,
                                FW_OPT_UEVENT | FW_OPT_NOCACHE);
        module_put(THIS_MODULE);
        return ret;
}
EXPORT_SYMBOL(request_firmware_into_buf);

/**
 * release_firmware() - release the resource associated with a firmware image
 * @fw: firmware resource to release
 **/
void release_firmware(const struct firmware *fw)
{
        if (fw) {
                if (!fw_is_builtin_firmware(fw))
                        firmware_free_data(fw);
                kfree(fw);
        }
}
EXPORT_SYMBOL(release_firmware);

/* Async support */
struct firmware_work {
        struct work_struct work;
        struct module *module;
        const char *name;
        struct device *device;
        void *context;
        void (*cont)(const struct firmware *fw, void *context);
        enum fw_opt opt_flags;
};

static void request_firmware_work_func(struct work_struct *work)
{
        struct firmware_work *fw_work;
        const struct firmware *fw;

        fw_work = container_of(work, struct firmware_work, work);

        _request_firmware(&fw, fw_work->name, fw_work->device, NULL, 0,
                          fw_work->opt_flags);
        fw_work->cont(fw, fw_work->context);
        put_device(fw_work->device); /* taken in request_firmware_nowait() */

        module_put(fw_work->module);
        kfree_const(fw_work->name);
        kfree(fw_work);
}

/**
 * request_firmware_nowait() - asynchronous version of request_firmware
 * @module: module requesting the firmware
 * @uevent: sends uevent to copy the firmware image if this flag
 *      is non-zero else the firmware copy must be done manually.
 * @name: name of firmware file
 * @device: device for which firmware is being loaded
 * @gfp: allocation flags
 * @context: will be passed over to @cont, and
 *      @fw may be %NULL if firmware request fails.
 * @cont: function will be called asynchronously when the firmware
 *      request is over.
 *
 *      Caller must hold the reference count of @device.
 *
 *      Asynchronous variant of request_firmware() for user contexts:
 *              - sleep for as small periods as possible since it may
 *                increase kernel boot time of built-in device drivers
 *                requesting firmware in their ->probe() methods, if
 *                @gfp is GFP_KERNEL.
 *
 *              - can't sleep at all if @gfp is GFP_ATOMIC.
 **/
int
request_firmware_nowait(
        struct module *module, bool uevent,
        const char *name, struct device *device, gfp_t gfp, void *context,
        void (*cont)(const struct firmware *fw, void *context))
{
        struct firmware_work *fw_work;

        fw_work = kzalloc(sizeof(struct firmware_work), gfp);
        if (!fw_work)
                return -ENOMEM;

        fw_work->module = module;
        fw_work->name = kstrdup_const(name, gfp);
        if (!fw_work->name) {
                kfree(fw_work);
                return -ENOMEM;
        }
        fw_work->device = device;
        fw_work->context = context;
        fw_work->cont = cont;
        fw_work->opt_flags = FW_OPT_NOWAIT |
                (uevent ? FW_OPT_UEVENT : FW_OPT_USERHELPER);

        if (!uevent && fw_cache_is_setup(device, name)) {
                kfree_const(fw_work->name);
                kfree(fw_work);
                return -EOPNOTSUPP;
        }

        if (!try_module_get(module)) {
                kfree_const(fw_work->name);
                kfree(fw_work);
                return -EFAULT;
        }

        get_device(fw_work->device);
        INIT_WORK(&fw_work->work, request_firmware_work_func);
        schedule_work(&fw_work->work);
        return 0;
}
EXPORT_SYMBOL(request_firmware_nowait);

#ifdef CONFIG_PM_SLEEP
static ASYNC_DOMAIN_EXCLUSIVE(fw_cache_domain);

/**
 * cache_firmware() - cache one firmware image in kernel memory space
 * @fw_name: the firmware image name
 *
 * Cache firmware in kernel memory so that drivers can use it when
 * system isn't ready for them to request firmware image from userspace.
 * Once it returns successfully, driver can use request_firmware or its
 * nowait version to get the cached firmware without any interacting
 * with userspace
 *
 * Return 0 if the firmware image has been cached successfully
 * Return !0 otherwise
 *
 */
static int cache_firmware(const char *fw_name)
{
        int ret;
        const struct firmware *fw;

        pr_debug("%s: %s\n", __func__, fw_name);

        ret = request_firmware(&fw, fw_name, NULL);
        if (!ret)
                kfree(fw);

        pr_debug("%s: %s ret=%d\n", __func__, fw_name, ret);

        return ret;
}

static struct fw_priv *lookup_fw_priv(const char *fw_name)
{
        struct fw_priv *tmp;
        struct firmware_cache *fwc = &fw_cache;

        spin_lock(&fwc->lock);
        tmp = __lookup_fw_priv(fw_name);
        spin_unlock(&fwc->lock);

        return tmp;
}

/**
 * uncache_firmware() - remove one cached firmware image
 * @fw_name: the firmware image name
 *
 * Uncache one firmware image which has been cached successfully
 * before.
 *
 * Return 0 if the firmware cache has been removed successfully
 * Return !0 otherwise
 *
 */
static int uncache_firmware(const char *fw_name)
{
        struct fw_priv *fw_priv;
        struct firmware fw;

        pr_debug("%s: %s\n", __func__, fw_name);

        if (fw_get_builtin_firmware(&fw, fw_name, NULL, 0))
                return 0;

        fw_priv = lookup_fw_priv(fw_name);
        if (fw_priv) {
                free_fw_priv(fw_priv);
                return 0;
        }

        return -EINVAL;
}

static struct fw_cache_entry *alloc_fw_cache_entry(const char *name)
{
        struct fw_cache_entry *fce;

        fce = kzalloc(sizeof(*fce), GFP_ATOMIC);
        if (!fce)
                goto exit;

        fce->name = kstrdup_const(name, GFP_ATOMIC);
        if (!fce->name) {
                kfree(fce);
                fce = NULL;
                goto exit;
        }
exit:
        return fce;
}

static int __fw_entry_found(const char *name)
{
        struct firmware_cache *fwc = &fw_cache;
        struct fw_cache_entry *fce;

        list_for_each_entry(fce, &fwc->fw_names, list) {
                if (!strcmp(fce->name, name))
                        return 1;
        }
        return 0;
}

static int fw_cache_piggyback_on_request(const char *name)
{
        struct firmware_cache *fwc = &fw_cache;
        struct fw_cache_entry *fce;
        int ret = 0;

        spin_lock(&fwc->name_lock);
        if (__fw_entry_found(name))
                goto found;

        fce = alloc_fw_cache_entry(name);
        if (fce) {
                ret = 1;
                list_add(&fce->list, &fwc->fw_names);
                pr_debug("%s: fw: %s\n", __func__, name);
        }
found:
        spin_unlock(&fwc->name_lock);
        return ret;
}

static void free_fw_cache_entry(struct fw_cache_entry *fce)
{
        kfree_const(fce->name);
        kfree(fce);
}

static void __async_dev_cache_fw_image(void *fw_entry,
                                       async_cookie_t cookie)
{
        struct fw_cache_entry *fce = fw_entry;
        struct firmware_cache *fwc = &fw_cache;
        int ret;

        ret = cache_firmware(fce->name);
        if (ret) {
                spin_lock(&fwc->name_lock);
                list_del(&fce->list);
                spin_unlock(&fwc->name_lock);

                free_fw_cache_entry(fce);
        }
}

/* called with dev->devres_lock held */
static void dev_create_fw_entry(struct device *dev, void *res,
                                void *data)
{
        struct fw_name_devm *fwn = res;
        const char *fw_name = fwn->name;
        struct list_head *head = data;
        struct fw_cache_entry *fce;

        fce = alloc_fw_cache_entry(fw_name);
        if (fce)
                list_add(&fce->list, head);
}

static int devm_name_match(struct device *dev, void *res,
                           void *match_data)
{
        struct fw_name_devm *fwn = res;
        return (fwn->magic == (unsigned long)match_data);
}

static void dev_cache_fw_image(struct device *dev, void *data)
{
        LIST_HEAD(todo);
        struct fw_cache_entry *fce;
        struct fw_cache_entry *fce_next;
        struct firmware_cache *fwc = &fw_cache;

        devres_for_each_res(dev, fw_name_devm_release,
                            devm_name_match, &fw_cache,
                            dev_create_fw_entry, &todo);

        list_for_each_entry_safe(fce, fce_next, &todo, list) {
                list_del(&fce->list);

                spin_lock(&fwc->name_lock);
                /* only one cache entry for one firmware */
                if (!__fw_entry_found(fce->name)) {
                        list_add(&fce->list, &fwc->fw_names);
                } else {
                        free_fw_cache_entry(fce);
                        fce = NULL;
                }
                spin_unlock(&fwc->name_lock);

                if (fce)
                        async_schedule_domain(__async_dev_cache_fw_image,
                                              (void *)fce,
                                              &fw_cache_domain);
        }
}

static void __device_uncache_fw_images(void)
{
        struct firmware_cache *fwc = &fw_cache;
        struct fw_cache_entry *fce;

        spin_lock(&fwc->name_lock);
        while (!list_empty(&fwc->fw_names)) {
                fce = list_entry(fwc->fw_names.next,
                                struct fw_cache_entry, list);
                list_del(&fce->list);
                spin_unlock(&fwc->name_lock);

                uncache_firmware(fce->name);
                free_fw_cache_entry(fce);

                spin_lock(&fwc->name_lock);
        }
        spin_unlock(&fwc->name_lock);
}

/**
 * device_cache_fw_images() - cache devices' firmware
 *
 * If one device called request_firmware or its nowait version
 * successfully before, the firmware names are recored into the
 * device's devres link list, so device_cache_fw_images can call
 * cache_firmware() to cache these firmwares for the device,
 * then the device driver can load its firmwares easily at
 * time when system is not ready to complete loading firmware.
 */
static void device_cache_fw_images(void)
{
        struct firmware_cache *fwc = &fw_cache;
        DEFINE_WAIT(wait);

        pr_debug("%s\n", __func__);

        /* cancel uncache work */
        cancel_delayed_work_sync(&fwc->work);

        fw_fallback_set_cache_timeout();

        mutex_lock(&fw_lock);
        fwc->state = FW_LOADER_START_CACHE;
        dpm_for_each_dev(NULL, dev_cache_fw_image);
        mutex_unlock(&fw_lock);

        /* wait for completion of caching firmware for all devices */
        async_synchronize_full_domain(&fw_cache_domain);

        fw_fallback_set_default_timeout();
}

/**
 * device_uncache_fw_images() - uncache devices' firmware
 *
 * uncache all firmwares which have been cached successfully
 * by device_uncache_fw_images earlier
 */
static void device_uncache_fw_images(void)
{
        pr_debug("%s\n", __func__);
        __device_uncache_fw_images();
}

static void device_uncache_fw_images_work(struct work_struct *work)
{
        device_uncache_fw_images();
}

/**
 * device_uncache_fw_images_delay() - uncache devices firmwares
 * @delay: number of milliseconds to delay uncache device firmwares
 *
 * uncache all devices's firmwares which has been cached successfully
 * by device_cache_fw_images after @delay milliseconds.
 */
static void device_uncache_fw_images_delay(unsigned long delay)
{
        queue_delayed_work(system_power_efficient_wq, &fw_cache.work,
                           msecs_to_jiffies(delay));
}

static int fw_pm_notify(struct notifier_block *notify_block,
                        unsigned long mode, void *unused)
{
        switch (mode) {
        case PM_HIBERNATION_PREPARE:
        case PM_SUSPEND_PREPARE:
        case PM_RESTORE_PREPARE:
                /*
                 * kill pending fallback requests with a custom fallback
                 * to avoid stalling suspend.
                 */
                kill_pending_fw_fallback_reqs(true);
                device_cache_fw_images();
                break;

        case PM_POST_SUSPEND:
        case PM_POST_HIBERNATION:
        case PM_POST_RESTORE:
                /*
                 * In case that system sleep failed and syscore_suspend is
                 * not called.
                 */
                mutex_lock(&fw_lock);
                fw_cache.state = FW_LOADER_NO_CACHE;
                mutex_unlock(&fw_lock);

                device_uncache_fw_images_delay(10 * MSEC_PER_SEC);
                break;
        }

        return 0;
}

/* stop caching firmware once syscore_suspend is reached */
static int fw_suspend(void)
{
        fw_cache.state = FW_LOADER_NO_CACHE;
        return 0;
}

static struct syscore_ops fw_syscore_ops = {
        .suspend = fw_suspend,
};

static int __init register_fw_pm_ops(void)
{
        int ret;

        spin_lock_init(&fw_cache.name_lock);
        INIT_LIST_HEAD(&fw_cache.fw_names);

        INIT_DELAYED_WORK(&fw_cache.work,
                          device_uncache_fw_images_work);

        fw_cache.pm_notify.notifier_call = fw_pm_notify;
        ret = register_pm_notifier(&fw_cache.pm_notify);
        if (ret)
                return ret;

        register_syscore_ops(&fw_syscore_ops);

        return ret;
}

static inline void unregister_fw_pm_ops(void)
{
        unregister_syscore_ops(&fw_syscore_ops);
        unregister_pm_notifier(&fw_cache.pm_notify);
}
#else
static int fw_cache_piggyback_on_request(const char *name)
{
        return 0;
}
static inline int register_fw_pm_ops(void)
{
        return 0;
}
static inline void unregister_fw_pm_ops(void)
{
}
#endif

static void __init fw_cache_init(void)
{
        spin_lock_init(&fw_cache.lock);
        INIT_LIST_HEAD(&fw_cache.head);
        fw_cache.state = FW_LOADER_NO_CACHE;
}

static int fw_shutdown_notify(struct notifier_block *unused1,
                              unsigned long unused2, void *unused3)
{
        /*
         * Kill all pending fallback requests to avoid both stalling shutdown,
         * and avoid a deadlock with the usermode_lock.
         */
        kill_pending_fw_fallback_reqs(false);

        return NOTIFY_DONE;
}

static struct notifier_block fw_shutdown_nb = {
        .notifier_call = fw_shutdown_notify,
};

static int __init firmware_class_init(void)
{
        int ret;

        /* No need to unfold these on exit */
        fw_cache_init();

        ret = register_fw_pm_ops();
        if (ret)
                return ret;

        ret = register_reboot_notifier(&fw_shutdown_nb);
        if (ret)
                goto out;

        return register_sysfs_loader();

out:
        unregister_fw_pm_ops();
        return ret;
}

static void __exit firmware_class_exit(void)
{
        unregister_fw_pm_ops();
        unregister_reboot_notifier(&fw_shutdown_nb);
        unregister_sysfs_loader();
}

fs_initcall(firmware_class_init);
module_exit(firmware_class_exit);