mm: memcontrol: use per-cpu stocks for socket memory uncharging

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

/*
 * firmware_class.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"

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

/* Builtin firmware support */

#ifdef CONFIG_FW_LOADER

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

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;

                        if (buf && fw->size <= size)
                                memcpy(buf, fw->data, fw->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

enum fw_status {
        FW_STATUS_UNKNOWN,
        FW_STATUS_LOADING,
        FW_STATUS_DONE,
        FW_STATUS_ABORTED,
};

static int loading_timeout = 60;        /* In seconds */

static inline long firmware_loading_timeout(void)
{
        return loading_timeout > 0 ? loading_timeout * HZ : MAX_JIFFY_OFFSET;
}

/*
 * Concurrent request_firmware() for the same firmware need to be
 * serialized.  struct fw_state is simple state machine which hold the
 * state of the firmware loading.
 */
struct fw_state {
        struct completion completion;
        enum fw_status status;
};

static void fw_state_init(struct fw_state *fw_st)
{
        init_completion(&fw_st->completion);
        fw_st->status = FW_STATUS_UNKNOWN;
}

static inline bool __fw_state_is_done(enum fw_status status)
{
        return status == FW_STATUS_DONE || status == FW_STATUS_ABORTED;
}

static int __fw_state_wait_common(struct fw_state *fw_st, long timeout)
{
        long ret;

        ret = wait_for_completion_killable_timeout(&fw_st->completion, timeout);
        if (ret != 0 && fw_st->status == FW_STATUS_ABORTED)
                return -ENOENT;
        if (!ret)
                return -ETIMEDOUT;

        return ret < 0 ? ret : 0;
}

static void __fw_state_set(struct fw_state *fw_st,
                           enum fw_status status)
{
        WRITE_ONCE(fw_st->status, status);

        if (status == FW_STATUS_DONE || status == FW_STATUS_ABORTED)
                complete_all(&fw_st->completion);
}

#define fw_state_start(fw_st)                                   \
        __fw_state_set(fw_st, FW_STATUS_LOADING)
#define fw_state_done(fw_st)                                    \
        __fw_state_set(fw_st, FW_STATUS_DONE)
#define fw_state_aborted(fw_st)                                 \
        __fw_state_set(fw_st, FW_STATUS_ABORTED)
#define fw_state_wait(fw_st)                                    \
        __fw_state_wait_common(fw_st, MAX_SCHEDULE_TIMEOUT)

static int __fw_state_check(struct fw_state *fw_st, enum fw_status status)
{
        return fw_st->status == status;
}

#define fw_state_is_aborted(fw_st)                              \
        __fw_state_check(fw_st, FW_STATUS_ABORTED)

#ifdef CONFIG_FW_LOADER_USER_HELPER

#define fw_state_aborted(fw_st)                                 \
        __fw_state_set(fw_st, FW_STATUS_ABORTED)
#define fw_state_is_done(fw_st)                                 \
        __fw_state_check(fw_st, FW_STATUS_DONE)
#define fw_state_is_loading(fw_st)                              \
        __fw_state_check(fw_st, FW_STATUS_LOADING)
#define fw_state_wait_timeout(fw_st, timeout)                   \
        __fw_state_wait_common(fw_st, timeout)

#endif /* CONFIG_FW_LOADER_USER_HELPER */

/* firmware behavior options */
#define FW_OPT_UEVENT   (1U << 0)
#define FW_OPT_NOWAIT   (1U << 1)
#ifdef CONFIG_FW_LOADER_USER_HELPER
#define FW_OPT_USERHELPER       (1U << 2)
#else
#define FW_OPT_USERHELPER       0
#endif
#ifdef CONFIG_FW_LOADER_USER_HELPER_FALLBACK
#define FW_OPT_FALLBACK         FW_OPT_USERHELPER
#else
#define FW_OPT_FALLBACK         0
#endif
#define FW_OPT_NO_WARN  (1U << 3)
#define FW_OPT_NOCACHE  (1U << 4)

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 firmware_buf {
        struct kref ref;
        struct list_head list;
        struct firmware_cache *fwc;
        struct fw_state fw_st;
        void *data;
        size_t size;
        size_t allocated_size;
#ifdef CONFIG_FW_LOADER_USER_HELPER
        bool is_paged_buf;
        bool need_uevent;
        struct page **pages;
        int nr_pages;
        int page_array_size;
        struct list_head pending_list;
#endif
        const char *fw_id;
};

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

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

#define to_fwbuf(d) container_of(d, struct firmware_buf, ref)

#define FW_LOADER_NO_CACHE      0
#define FW_LOADER_START_CACHE   1

static int fw_cache_piggyback_on_request(const char *name);

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

static bool __enable_firmware = false;

static void enable_firmware(void)
{
        mutex_lock(&fw_lock);
        __enable_firmware = true;
        mutex_unlock(&fw_lock);
}

static void disable_firmware(void)
{
        mutex_lock(&fw_lock);
        __enable_firmware = false;
        mutex_unlock(&fw_lock);
}

/*
 * When disabled only the built-in firmware and the firmware cache will be
 * used to look for firmware.
 */
static bool firmware_enabled(void)
{
        bool enabled = false;

        mutex_lock(&fw_lock);
        if (__enable_firmware)
                enabled = true;
        mutex_unlock(&fw_lock);

        return enabled;
}

static struct firmware_cache fw_cache;

static struct firmware_buf *__allocate_fw_buf(const char *fw_name,
                                              struct firmware_cache *fwc,
                                              void *dbuf, size_t size)
{
        struct firmware_buf *buf;

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

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

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

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

        return buf;
}

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

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

/* Returns 1 for batching firmware requests with the same name */
static int fw_lookup_and_allocate_buf(const char *fw_name,
                                      struct firmware_cache *fwc,
                                      struct firmware_buf **buf, void *dbuf,
                                      size_t size)
{
        struct firmware_buf *tmp;

        spin_lock(&fwc->lock);
        tmp = __fw_lookup_buf(fw_name);
        if (tmp) {
                kref_get(&tmp->ref);
                spin_unlock(&fwc->lock);
                *buf = tmp;
                pr_debug("batched request - sharing the same struct firmware_buf and lookup for multiple requests\n");
                return 1;
        }
        tmp = __allocate_fw_buf(fw_name, fwc, dbuf, size);
        if (tmp)
                list_add(&tmp->list, &fwc->head);
        spin_unlock(&fwc->lock);

        *buf = tmp;

        return tmp ? 0 : -ENOMEM;
}

static void __fw_free_buf(struct kref *ref)
        __releases(&fwc->lock)
{
        struct firmware_buf *buf = to_fwbuf(ref);
        struct firmware_cache *fwc = buf->fwc;

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

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

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

static void fw_free_buf(struct firmware_buf *buf)
{
        struct firmware_cache *fwc = buf->fwc;
        spin_lock(&fwc->lock);
        if (!kref_put(&buf->ref, __fw_free_buf))
                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 firmware_buf *buf)
{
        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 (buf->data) {
                id = READING_FIRMWARE_PREALLOC_BUFFER;
                msize = buf->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], buf->fw_id);
                if (len >= PATH_MAX) {
                        rc = -ENAMETOOLONG;
                        break;
                }

                buf->size = 0;
                rc = kernel_read_file_from_path(path, &buf->data, &size, msize,
                                                id);
                if (rc) {
                        if (rc == -ENOENT)
                                dev_dbg(device, "loading %s failed with error %d\n",
                                         path, rc);
                        else
                                dev_warn(device, "loading %s failed with error %d\n",
                                         path, rc);
                        continue;
                }
                dev_dbg(device, "direct-loading %s\n", buf->fw_id);
                buf->size = size;
                fw_state_done(&buf->fw_st);
                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;
        }
        fw_free_buf(fw->priv);
}

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

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

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

        fwn = fw_find_devm_name(dev, name);
        if (fwn)
                return 1;

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

static int assign_firmware_buf(struct firmware *fw, struct device *device,
                               unsigned int opt_flags)
{
        struct firmware_buf *buf = fw->priv;

        mutex_lock(&fw_lock);
        if (!buf->size || fw_state_is_aborted(&buf->fw_st)) {
                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))
                fw_add_devm_name(device, buf->fw_id);

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

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

/*
 * user-mode helper code
 */
#ifdef CONFIG_FW_LOADER_USER_HELPER
struct firmware_priv {
        bool nowait;
        struct device dev;
        struct firmware_buf *buf;
        struct firmware *fw;
};

static struct firmware_priv *to_firmware_priv(struct device *dev)
{
        return container_of(dev, struct firmware_priv, dev);
}

static void __fw_load_abort(struct firmware_buf *buf)
{
        /*
         * There is a small window in which user can write to 'loading'
         * between loading done and disappearance of 'loading'
         */
        if (fw_state_is_done(&buf->fw_st))
                return;

        list_del_init(&buf->pending_list);
        fw_state_aborted(&buf->fw_st);
}

static void fw_load_abort(struct firmware_priv *fw_priv)
{
        struct firmware_buf *buf = fw_priv->buf;

        __fw_load_abort(buf);
}

static LIST_HEAD(pending_fw_head);

static void kill_pending_fw_fallback_reqs(bool only_kill_custom)
{
        struct firmware_buf *buf;
        struct firmware_buf *next;

        mutex_lock(&fw_lock);
        list_for_each_entry_safe(buf, next, &pending_fw_head, pending_list) {
                if (!buf->need_uevent || !only_kill_custom)
                         __fw_load_abort(buf);
        }
        mutex_unlock(&fw_lock);
}

static ssize_t timeout_show(struct class *class, struct class_attribute *attr,
                            char *buf)
{
        return sprintf(buf, "%d\n", loading_timeout);
}

/**
 * firmware_timeout_store - set number of seconds to wait for firmware
 * @class: device class pointer
 * @attr: device attribute pointer
 * @buf: buffer to scan for timeout value
 * @count: number of bytes in @buf
 *
 *      Sets the number of seconds to wait for the firmware.  Once
 *      this expires an error will be returned to the driver and no
 *      firmware will be provided.
 *
 *      Note: zero means 'wait forever'.
 **/
static ssize_t timeout_store(struct class *class, struct class_attribute *attr,
                             const char *buf, size_t count)
{
        loading_timeout = simple_strtol(buf, NULL, 10);
        if (loading_timeout < 0)
                loading_timeout = 0;

        return count;
}
static CLASS_ATTR_RW(timeout);

static struct attribute *firmware_class_attrs[] = {
        &class_attr_timeout.attr,
        NULL,
};
ATTRIBUTE_GROUPS(firmware_class);

static void fw_dev_release(struct device *dev)
{
        struct firmware_priv *fw_priv = to_firmware_priv(dev);

        kfree(fw_priv);
}

static int do_firmware_uevent(struct firmware_priv *fw_priv, struct kobj_uevent_env *env)
{
        if (add_uevent_var(env, "FIRMWARE=%s", fw_priv->buf->fw_id))
                return -ENOMEM;
        if (add_uevent_var(env, "TIMEOUT=%i", loading_timeout))
                return -ENOMEM;
        if (add_uevent_var(env, "ASYNC=%d", fw_priv->nowait))
                return -ENOMEM;

        return 0;
}

static int firmware_uevent(struct device *dev, struct kobj_uevent_env *env)
{
        struct firmware_priv *fw_priv = to_firmware_priv(dev);
        int err = 0;

        mutex_lock(&fw_lock);
        if (fw_priv->buf)
                err = do_firmware_uevent(fw_priv, env);
        mutex_unlock(&fw_lock);
        return err;
}

static struct class firmware_class = {
        .name           = "firmware",
        .class_groups   = firmware_class_groups,
        .dev_uevent     = firmware_uevent,
        .dev_release    = fw_dev_release,
};

static ssize_t firmware_loading_show(struct device *dev,
                                     struct device_attribute *attr, char *buf)
{
        struct firmware_priv *fw_priv = to_firmware_priv(dev);
        int loading = 0;

        mutex_lock(&fw_lock);
        if (fw_priv->buf)
                loading = fw_state_is_loading(&fw_priv->buf->fw_st);
        mutex_unlock(&fw_lock);

        return sprintf(buf, "%d\n", loading);
}

/* Some architectures don't have PAGE_KERNEL_RO */
#ifndef PAGE_KERNEL_RO
#define PAGE_KERNEL_RO PAGE_KERNEL
#endif

/* one pages buffer should be mapped/unmapped only once */
static int fw_map_pages_buf(struct firmware_buf *buf)
{
        if (!buf->is_paged_buf)
                return 0;

        vunmap(buf->data);
        buf->data = vmap(buf->pages, buf->nr_pages, 0, PAGE_KERNEL_RO);
        if (!buf->data)
                return -ENOMEM;
        return 0;
}

/**
 * firmware_loading_store - set value in the 'loading' control file
 * @dev: device pointer
 * @attr: device attribute pointer
 * @buf: buffer to scan for loading control value
 * @count: number of bytes in @buf
 *
 *      The relevant values are:
 *
 *       1: Start a load, discarding any previous partial load.
 *       0: Conclude the load and hand the data to the driver code.
 *      -1: Conclude the load with an error and discard any written data.
 **/
static ssize_t firmware_loading_store(struct device *dev,
                                      struct device_attribute *attr,
                                      const char *buf, size_t count)
{
        struct firmware_priv *fw_priv = to_firmware_priv(dev);
        struct firmware_buf *fw_buf;
        ssize_t written = count;
        int loading = simple_strtol(buf, NULL, 10);
        int i;

        mutex_lock(&fw_lock);
        fw_buf = fw_priv->buf;
        if (fw_state_is_aborted(&fw_buf->fw_st))
                goto out;

        switch (loading) {
        case 1:
                /* discarding any previous partial load */
                if (!fw_state_is_done(&fw_buf->fw_st)) {
                        for (i = 0; i < fw_buf->nr_pages; i++)
                                __free_page(fw_buf->pages[i]);
                        vfree(fw_buf->pages);
                        fw_buf->pages = NULL;
                        fw_buf->page_array_size = 0;
                        fw_buf->nr_pages = 0;
                        fw_state_start(&fw_buf->fw_st);
                }
                break;
        case 0:
                if (fw_state_is_loading(&fw_buf->fw_st)) {
                        int rc;

                        /*
                         * Several loading requests may be pending on
                         * one same firmware buf, so let all requests
                         * see the mapped 'buf->data' once the loading
                         * is completed.
                         * */
                        rc = fw_map_pages_buf(fw_buf);
                        if (rc)
                                dev_err(dev, "%s: map pages failed\n",
                                        __func__);
                        else
                                rc = security_kernel_post_read_file(NULL,
                                                fw_buf->data, fw_buf->size,
                                                READING_FIRMWARE);

                        /*
                         * Same logic as fw_load_abort, only the DONE bit
                         * is ignored and we set ABORT only on failure.
                         */
                        list_del_init(&fw_buf->pending_list);
                        if (rc) {
                                fw_state_aborted(&fw_buf->fw_st);
                                written = rc;
                        } else {
                                fw_state_done(&fw_buf->fw_st);
                        }
                        break;
                }
                /* fallthrough */
        default:
                dev_err(dev, "%s: unexpected value (%d)\n", __func__, loading);
                /* fallthrough */
        case -1:
                fw_load_abort(fw_priv);
                break;
        }
out:
        mutex_unlock(&fw_lock);
        return written;
}

static DEVICE_ATTR(loading, 0644, firmware_loading_show, firmware_loading_store);

static void firmware_rw_buf(struct firmware_buf *buf, char *buffer,
                           loff_t offset, size_t count, bool read)
{
        if (read)
                memcpy(buffer, buf->data + offset, count);
        else
                memcpy(buf->data + offset, buffer, count);
}

static void firmware_rw(struct firmware_buf *buf, char *buffer,
                        loff_t offset, size_t count, bool read)
{
        while (count) {
                void *page_data;
                int page_nr = offset >> PAGE_SHIFT;
                int page_ofs = offset & (PAGE_SIZE-1);
                int page_cnt = min_t(size_t, PAGE_SIZE - page_ofs, count);

                page_data = kmap(buf->pages[page_nr]);

                if (read)
                        memcpy(buffer, page_data + page_ofs, page_cnt);
                else
                        memcpy(page_data + page_ofs, buffer, page_cnt);

                kunmap(buf->pages[page_nr]);
                buffer += page_cnt;
                offset += page_cnt;
                count -= page_cnt;
        }
}

static ssize_t firmware_data_read(struct file *filp, struct kobject *kobj,
                                  struct bin_attribute *bin_attr,
                                  char *buffer, loff_t offset, size_t count)
{
        struct device *dev = kobj_to_dev(kobj);
        struct firmware_priv *fw_priv = to_firmware_priv(dev);
        struct firmware_buf *buf;
        ssize_t ret_count;

        mutex_lock(&fw_lock);
        buf = fw_priv->buf;
        if (!buf || fw_state_is_done(&buf->fw_st)) {
                ret_count = -ENODEV;
                goto out;
        }
        if (offset > buf->size) {
                ret_count = 0;
                goto out;
        }
        if (count > buf->size - offset)
                count = buf->size - offset;

        ret_count = count;

        if (buf->data)
                firmware_rw_buf(buf, buffer, offset, count, true);
        else
                firmware_rw(buf, buffer, offset, count, true);

out:
        mutex_unlock(&fw_lock);
        return ret_count;
}

static int fw_realloc_buffer(struct firmware_priv *fw_priv, int min_size)
{
        struct firmware_buf *buf = fw_priv->buf;
        int pages_needed = PAGE_ALIGN(min_size) >> PAGE_SHIFT;

        /* If the array of pages is too small, grow it... */
        if (buf->page_array_size < pages_needed) {
                int new_array_size = max(pages_needed,
                                         buf->page_array_size * 2);
                struct page **new_pages;

                new_pages = vmalloc(new_array_size * sizeof(void *));
                if (!new_pages) {
                        fw_load_abort(fw_priv);
                        return -ENOMEM;
                }
                memcpy(new_pages, buf->pages,
                       buf->page_array_size * sizeof(void *));
                memset(&new_pages[buf->page_array_size], 0, sizeof(void *) *
                       (new_array_size - buf->page_array_size));
                vfree(buf->pages);
                buf->pages = new_pages;
                buf->page_array_size = new_array_size;
        }

        while (buf->nr_pages < pages_needed) {
                buf->pages[buf->nr_pages] =
                        alloc_page(GFP_KERNEL | __GFP_HIGHMEM);

                if (!buf->pages[buf->nr_pages]) {
                        fw_load_abort(fw_priv);
                        return -ENOMEM;
                }
                buf->nr_pages++;
        }
        return 0;
}

/**
 * firmware_data_write - write method for firmware
 * @filp: open sysfs file
 * @kobj: kobject for the device
 * @bin_attr: bin_attr structure
 * @buffer: buffer being written
 * @offset: buffer offset for write in total data store area
 * @count: buffer size
 *
 *      Data written to the 'data' attribute will be later handed to
 *      the driver as a firmware image.
 **/
static ssize_t firmware_data_write(struct file *filp, struct kobject *kobj,
                                   struct bin_attribute *bin_attr,
                                   char *buffer, loff_t offset, size_t count)
{
        struct device *dev = kobj_to_dev(kobj);
        struct firmware_priv *fw_priv = to_firmware_priv(dev);
        struct firmware_buf *buf;
        ssize_t retval;

        if (!capable(CAP_SYS_RAWIO))
                return -EPERM;

        mutex_lock(&fw_lock);
        buf = fw_priv->buf;
        if (!buf || fw_state_is_done(&buf->fw_st)) {
                retval = -ENODEV;
                goto out;
        }

        if (buf->data) {
                if (offset + count > buf->allocated_size) {
                        retval = -ENOMEM;
                        goto out;
                }
                firmware_rw_buf(buf, buffer, offset, count, false);
                retval = count;
        } else {
                retval = fw_realloc_buffer(fw_priv, offset + count);
                if (retval)
                        goto out;

                retval = count;
                firmware_rw(buf, buffer, offset, count, false);
        }

        buf->size = max_t(size_t, offset + count, buf->size);
out:
        mutex_unlock(&fw_lock);
        return retval;
}

static struct bin_attribute firmware_attr_data = {
        .attr = { .name = "data", .mode = 0644 },
        .size = 0,
        .read = firmware_data_read,
        .write = firmware_data_write,
};

static struct attribute *fw_dev_attrs[] = {
        &dev_attr_loading.attr,
        NULL
};

static struct bin_attribute *fw_dev_bin_attrs[] = {
        &firmware_attr_data,
        NULL
};

static const struct attribute_group fw_dev_attr_group = {
        .attrs = fw_dev_attrs,
        .bin_attrs = fw_dev_bin_attrs,
};

static const struct attribute_group *fw_dev_attr_groups[] = {
        &fw_dev_attr_group,
        NULL
};

static struct firmware_priv *
fw_create_instance(struct firmware *firmware, const char *fw_name,
                   struct device *device, unsigned int opt_flags)
{
        struct firmware_priv *fw_priv;
        struct device *f_dev;

        fw_priv = kzalloc(sizeof(*fw_priv), GFP_KERNEL);
        if (!fw_priv) {
                fw_priv = ERR_PTR(-ENOMEM);
                goto exit;
        }

        fw_priv->nowait = !!(opt_flags & FW_OPT_NOWAIT);
        fw_priv->fw = firmware;
        f_dev = &fw_priv->dev;

        device_initialize(f_dev);
        dev_set_name(f_dev, "%s", fw_name);
        f_dev->parent = device;
        f_dev->class = &firmware_class;
        f_dev->groups = fw_dev_attr_groups;
exit:
        return fw_priv;
}

/* load a firmware via user helper */
static int _request_firmware_load(struct firmware_priv *fw_priv,
                                  unsigned int opt_flags, long timeout)
{
        int retval = 0;
        struct device *f_dev = &fw_priv->dev;
        struct firmware_buf *buf = fw_priv->buf;

        /* fall back on userspace loading */
        if (!buf->data)
                buf->is_paged_buf = true;

        dev_set_uevent_suppress(f_dev, true);

        retval = device_add(f_dev);
        if (retval) {
                dev_err(f_dev, "%s: device_register failed\n", __func__);
                goto err_put_dev;
        }

        mutex_lock(&fw_lock);
        list_add(&buf->pending_list, &pending_fw_head);
        mutex_unlock(&fw_lock);

        if (opt_flags & FW_OPT_UEVENT) {
                buf->need_uevent = true;
                dev_set_uevent_suppress(f_dev, false);
                dev_dbg(f_dev, "firmware: requesting %s\n", buf->fw_id);
                kobject_uevent(&fw_priv->dev.kobj, KOBJ_ADD);
        } else {
                timeout = MAX_JIFFY_OFFSET;
        }

        retval = fw_state_wait_timeout(&buf->fw_st, timeout);
        if (retval < 0) {
                mutex_lock(&fw_lock);
                fw_load_abort(fw_priv);
                mutex_unlock(&fw_lock);
        }

        if (fw_state_is_aborted(&buf->fw_st)) {
                if (retval == -ERESTARTSYS)
                        retval = -EINTR;
                else
                        retval = -EAGAIN;
        } else if (buf->is_paged_buf && !buf->data)
                retval = -ENOMEM;

        device_del(f_dev);
err_put_dev:
        put_device(f_dev);
        return retval;
}

static int fw_load_from_user_helper(struct firmware *firmware,
                                    const char *name, struct device *device,
                                    unsigned int opt_flags)
{
        struct firmware_priv *fw_priv;
        long timeout;
        int ret;

        timeout = firmware_loading_timeout();
        if (opt_flags & FW_OPT_NOWAIT) {
                timeout = usermodehelper_read_lock_wait(timeout);
                if (!timeout) {
                        dev_dbg(device, "firmware: %s loading timed out\n",
                                name);
                        return -EBUSY;
                }
        } else {
                ret = usermodehelper_read_trylock();
                if (WARN_ON(ret)) {
                        dev_err(device, "firmware: %s will not be loaded\n",
                                name);
                        return ret;
                }
        }

        fw_priv = fw_create_instance(firmware, name, device, opt_flags);
        if (IS_ERR(fw_priv)) {
                ret = PTR_ERR(fw_priv);
                goto out_unlock;
        }

        fw_priv->buf = firmware->priv;
        ret = _request_firmware_load(fw_priv, opt_flags, timeout);

        if (!ret)
                ret = assign_firmware_buf(firmware, device, opt_flags);

out_unlock:
        usermodehelper_read_unlock();

        return ret;
}

#else /* CONFIG_FW_LOADER_USER_HELPER */
static inline int
fw_load_from_user_helper(struct firmware *firmware, const char *name,
                         struct device *device, unsigned int opt_flags)
{
        return -ENOENT;
}

static inline void kill_pending_fw_fallback_reqs(bool only_kill_custom) { }

#endif /* CONFIG_FW_LOADER_USER_HELPER */

/* 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)
{
        struct firmware *firmware;
        struct firmware_buf *buf;
        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 = fw_lookup_and_allocate_buf(name, &fw_cache, &buf, dbuf, size);

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

        if (ret > 0) {
                ret = fw_state_wait(&buf->fw_st);
                if (!ret) {
                        fw_set_page_data(buf, 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 firmware_buf 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 firmware_buf *buf;

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

        buf = fw->priv;
        if (!fw_state_is_aborted(&buf->fw_st))
                fw_state_aborted(&buf->fw_st);
}

/* 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,
                  unsigned int 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);
        if (ret <= 0) /* error or already assigned */
                goto out;

        if (!firmware_enabled()) {
                WARN(1, "firmware request while host is not available\n");
                ret = -EHOSTDOWN;
                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);
                if (opt_flags & FW_OPT_USERHELPER) {
                        dev_warn(device, "Falling back to user helper\n");
                        ret = fw_load_from_user_helper(fw, name, device,
                                                       opt_flags);
                }
        } else
                ret = assign_firmware_buf(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 | FW_OPT_FALLBACK);
        module_put(THIS_MODULE);
        return ret;
}
EXPORT_SYMBOL(request_firmware);

/**
 * 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);
        module_put(THIS_MODULE);
        return ret;
}
EXPORT_SYMBOL_GPL(request_firmware_direct);

/**
 * 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;

        __module_get(THIS_MODULE);
        ret = _request_firmware(firmware_p, name, device, buf, size,
                                FW_OPT_UEVENT | FW_OPT_FALLBACK |
                                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);
        unsigned int 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 | FW_OPT_FALLBACK |
                (uevent ? FW_OPT_UEVENT : FW_OPT_USERHELPER);

        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 firmware_buf *fw_lookup_buf(const char *fw_name)
{
        struct firmware_buf *tmp;
        struct firmware_cache *fwc = &fw_cache;

        spin_lock(&fwc->lock);
        tmp = __fw_lookup_buf(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 firmware_buf *buf;
        struct firmware fw;

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

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

        buf = fw_lookup_buf(fw_name);
        if (buf) {
                fw_free_buf(buf);
                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;
        int old_timeout;
        DEFINE_WAIT(wait);

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

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

        /*
         * use small loading timeout for caching devices' firmware
         * because all these firmware images have been loaded
         * successfully at lease once, also system is ready for
         * completing firmware loading now. The maximum size of
         * firmware in current distributions is about 2M bytes,
         * so 10 secs should be enough.
         */
        old_timeout = loading_timeout;
        loading_timeout = 10;

        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);

        loading_timeout = old_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));
}

/**
 * fw_pm_notify - notifier for suspend/resume
 * @notify_block: unused
 * @mode: mode we are switching to
 * @unused: unused
 *
 * Used to modify the firmware_class state as we move in between states.
 * The firmware_class implements a firmware cache to enable device driver
 * to fetch firmware upon resume before the root filesystem is ready. We
 * disable API calls which do not use the built-in firmware or the firmware
 * cache when we know these calls will not work.
 *
 * The inner logic behind all this is a bit complex so it is worth summarizing
 * the kernel's own suspend/resume process with context and focus on how this
 * can impact the firmware API.
 *
 * First a review on how we go to suspend::
 *
 *      pm_suspend() --> enter_state() -->
 *      sys_sync()
 *      suspend_prepare() -->
 *              __pm_notifier_call_chain(PM_SUSPEND_PREPARE, ...);
 *              suspend_freeze_processes() -->
 *                      freeze_processes() -->
 *                              __usermodehelper_set_disable_depth(UMH_DISABLED);
 *                              freeze all tasks ...
 *                      freeze_kernel_threads()
 *      suspend_devices_and_enter() -->
 *              dpm_suspend_start() -->
 *                              dpm_prepare()
 *                              dpm_suspend()
 *              suspend_enter()  -->
 *                      platform_suspend_prepare()
 *                      dpm_suspend_late()
 *                      freeze_enter()
 *                      syscore_suspend()
 *
 * When we resume we bail out of a loop from suspend_devices_and_enter() and
 * unwind back out to the caller enter_state() where we were before as follows::
 *
 *      enter_state() -->
 *      suspend_devices_and_enter() --> (bail from loop)
 *              dpm_resume_end() -->
 *                      dpm_resume()
 *                      dpm_complete()
 *      suspend_finish() -->
 *              suspend_thaw_processes() -->
 *                      thaw_processes() -->
 *                              __usermodehelper_set_disable_depth(UMH_FREEZING);
 *                              thaw_workqueues();
 *                              thaw all processes ...
 *                              usermodehelper_enable();
 *              pm_notifier_call_chain(PM_POST_SUSPEND);
 *
 * fw_pm_notify() works through pm_notifier_call_chain().
 */
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();
                disable_firmware();
                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);
                enable_firmware();

                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,
};
#else
static int fw_cache_piggyback_on_request(const char *name)
{
        return 0;
}
#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;

#ifdef CONFIG_PM_SLEEP
        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;
        register_pm_notifier(&fw_cache.pm_notify);

        register_syscore_ops(&fw_syscore_ops);
#endif
}

static int fw_shutdown_notify(struct notifier_block *unused1,
                              unsigned long unused2, void *unused3)
{
        disable_firmware();
        /*
         * 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)
{
        enable_firmware();
        fw_cache_init();
        register_reboot_notifier(&fw_shutdown_nb);
#ifdef CONFIG_FW_LOADER_USER_HELPER
        return class_register(&firmware_class);
#else
        return 0;
#endif
}

static void __exit firmware_class_exit(void)
{
        disable_firmware();
#ifdef CONFIG_PM_SLEEP
        unregister_syscore_ops(&fw_syscore_ops);
        unregister_pm_notifier(&fw_cache.pm_notify);
#endif
        unregister_reboot_notifier(&fw_shutdown_nb);
#ifdef CONFIG_FW_LOADER_USER_HELPER
        class_unregister(&firmware_class);
#endif
}

fs_initcall(firmware_class_init);
module_exit(firmware_class_exit);