/*
 * kernel/power/compression.c
 *
 * Copyright (C) 2003-2015 Nigel Cunningham (nigel at nigelcunningham com au)
 *
 * This file is released under the GPLv2.
 *
 * This file contains data compression routines for TuxOnIce,
 * using cryptoapi.
 */

#include <linux/suspend.h>
#include <linux/highmem.h>
#include <linux/vmalloc.h>
#include <linux/crypto.h>

#include "tuxonice_builtin.h"
#include "tuxonice.h"
#include "tuxonice_modules.h"
#include "tuxonice_sysfs.h"
#include "tuxonice_io.h"
#include "tuxonice_ui.h"
#include "tuxonice_alloc.h"

static int toi_expected_compression;

static struct toi_module_ops toi_compression_ops;
static struct toi_module_ops *next_driver;

static char toi_compressor_name[32] = "lzo";

static DEFINE_MUTEX(stats_lock);

struct cpu_context {
        u8 *page_buffer;
        struct crypto_comp *transform;
        unsigned int len;
        u8 *buffer_start;
        u8 *output_buffer;
};

#define OUT_BUF_SIZE (2 * PAGE_SIZE)

static DEFINE_PER_CPU(struct cpu_context, contexts);

/*
 * toi_crypto_prepare
 *
 * Prepare to do some work by allocating buffers and transforms.
 */
static int toi_compress_crypto_prepare(void)
{
        int cpu;

        if (!*toi_compressor_name) {
                printk(KERN_INFO "TuxOnIce: Compression enabled but no "
                                "compressor name set.\n");
                return 1;
        }

        for_each_online_cpu(cpu) {
                struct cpu_context *this = &per_cpu(contexts, cpu);
                this->transform = crypto_alloc_comp(toi_compressor_name, 0, 0);
                if (IS_ERR(this->transform)) {
                        printk(KERN_INFO "TuxOnIce: Failed to initialise the "
                                        "%s compression transform.\n",
                                        toi_compressor_name);
                        this->transform = NULL;
                        return 1;
                }

                this->page_buffer =
                        (char *) toi_get_zeroed_page(16, TOI_ATOMIC_GFP);

                if (!this->page_buffer) {
                        printk(KERN_ERR
                          "Failed to allocate a page buffer for TuxOnIce "
                          "compression driver.\n");
                        return -ENOMEM;
                }

                this->output_buffer =
                        (char *) vmalloc_32(OUT_BUF_SIZE);

                if (!this->output_buffer) {
                        printk(KERN_ERR
                          "Failed to allocate a output buffer for TuxOnIce "
                          "compression driver.\n");
                        return -ENOMEM;
                }
        }

        return 0;
}

static int toi_compress_rw_cleanup(int writing)
{
        int cpu;

        for_each_online_cpu(cpu) {
                struct cpu_context *this = &per_cpu(contexts, cpu);
                if (this->transform) {
                        crypto_free_comp(this->transform);
                        this->transform = NULL;
                }

                if (this->page_buffer)
                        toi_free_page(16, (unsigned long) this->page_buffer);

                this->page_buffer = NULL;

                if (this->output_buffer)
                        vfree(this->output_buffer);

                this->output_buffer = NULL;
        }

        return 0;
}

/*
 * toi_compress_init
 */

static int toi_compress_init(int toi_or_resume)
{
        if (!toi_or_resume)
                return 0;

        toi_compress_bytes_in = 0;
        toi_compress_bytes_out = 0;

        next_driver = toi_get_next_filter(&toi_compression_ops);

        return next_driver ? 0 : -ECHILD;
}

/*
 * toi_compress_rw_init()
 */

static int toi_compress_rw_init(int rw, int stream_number)
{
        if (toi_compress_crypto_prepare()) {
                printk(KERN_ERR "Failed to initialise compression "
                                "algorithm.\n");
                if (rw == READ) {
                        printk(KERN_INFO "Unable to read the image.\n");
                        return -ENODEV;
                } else {
                        printk(KERN_INFO "Continuing without "
                                "compressing the image.\n");
                        toi_compression_ops.enabled = 0;
                }
        }

        return 0;
}

/*
 * toi_compress_write_page()
 *
 * Compress a page of data, buffering output and passing on filled
 * pages to the next module in the pipeline.
 *
 * Buffer_page:        Pointer to a buffer of size PAGE_SIZE, containing
 * data to be compressed.
 *
 * Returns:        0 on success. Otherwise the error is that returned by later
 *                 modules, -ECHILD if we have a broken pipeline or -EIO if
 *                 zlib errs.
 */
static int toi_compress_write_page(unsigned long index, int buf_type,
                void *buffer_page, unsigned int buf_size)
{
        int ret = 0, cpu = smp_processor_id();
        struct cpu_context *ctx = &per_cpu(contexts, cpu);
        u8* output_buffer = buffer_page;
        int output_len = buf_size;
        int out_buf_type = buf_type;

        if (ctx->transform) {

                ctx->buffer_start = TOI_MAP(buf_type, buffer_page);
                ctx->len = OUT_BUF_SIZE;

                ret = crypto_comp_compress(ctx->transform,
                        ctx->buffer_start, buf_size,
                        ctx->output_buffer, &ctx->len);

                TOI_UNMAP(buf_type, buffer_page);

                toi_message(TOI_COMPRESS, TOI_VERBOSE, 0,
                                "CPU %d, index %lu: %d bytes",
                                cpu, index, ctx->len);

                if (!ret && ctx->len < buf_size) { /* some compression */
                        output_buffer = ctx->output_buffer;
                        output_len = ctx->len;
                        out_buf_type = TOI_VIRT;
                }

        }

        mutex_lock(&stats_lock);

        toi_compress_bytes_in += buf_size;
        toi_compress_bytes_out += output_len;

        mutex_unlock(&stats_lock);

        if (!ret)
                ret = next_driver->write_page(index, out_buf_type,
                                output_buffer, output_len);

        return ret;
}

/*
 * toi_compress_read_page()
 * @buffer_page: struct page *. Pointer to a buffer of size PAGE_SIZE.
 *
 * Retrieve data from later modules and decompress it until the input buffer
 * is filled.
 * Zero if successful. Error condition from me or from downstream on failure.
 */
static int toi_compress_read_page(unsigned long *index, int buf_type,
                void *buffer_page, unsigned int *buf_size)
{
        int ret, cpu = smp_processor_id();
        unsigned int len;
        unsigned int outlen = PAGE_SIZE;
        char *buffer_start;
        struct cpu_context *ctx = &per_cpu(contexts, cpu);

        if (!ctx->transform)
                return next_driver->read_page(index, TOI_PAGE, buffer_page,
                                buf_size);

        /*
         * All our reads must be synchronous - we can't decompress
         * data that hasn't been read yet.
         */

        ret = next_driver->read_page(index, TOI_VIRT, ctx->page_buffer, &len);

        buffer_start = kmap(buffer_page);

        /* Error or uncompressed data */
        if (ret || len == PAGE_SIZE) {
                memcpy(buffer_start, ctx->page_buffer, len);
                goto out;
        }

        ret = crypto_comp_decompress(
                        ctx->transform,
                        ctx->page_buffer,
                        len, buffer_start, &outlen);

        toi_message(TOI_COMPRESS, TOI_VERBOSE, 0,
                        "CPU %d, index %lu: %d=>%d (%d).",
                        cpu, *index, len, outlen, ret);

        if (ret)
                abort_hibernate(TOI_FAILED_IO,
                        "Compress_read returned %d.\n", ret);
        else if (outlen != PAGE_SIZE) {
                abort_hibernate(TOI_FAILED_IO,
                        "Decompression yielded %d bytes instead of %ld.\n",
                        outlen, PAGE_SIZE);
                printk(KERN_ERR "Decompression yielded %d bytes instead of "
                                "%ld.\n", outlen, PAGE_SIZE);
                ret = -EIO;
                *buf_size = outlen;
        }
out:
        TOI_UNMAP(buf_type, buffer_page);
        return ret;
}

/*
 * toi_compress_print_debug_stats
 * @buffer: Pointer to a buffer into which the debug info will be printed.
 * @size: Size of the buffer.
 *
 * Print information to be recorded for debugging purposes into a buffer.
 * Returns: Number of characters written to the buffer.
 */

static int toi_compress_print_debug_stats(char *buffer, int size)
{
        unsigned long pages_in = toi_compress_bytes_in >> PAGE_SHIFT,
                      pages_out = toi_compress_bytes_out >> PAGE_SHIFT;
        int len;

        /* Output the compression ratio achieved. */
        if (*toi_compressor_name)
                len = scnprintf(buffer, size, "- Compressor is '%s'.\n",
                                toi_compressor_name);
        else
                len = scnprintf(buffer, size, "- Compressor is not set.\n");

        if (pages_in)
                len += scnprintf(buffer+len, size - len, "  Compressed "
                        "%lu bytes into %lu (%ld percent compression).\n",
                  toi_compress_bytes_in,
                  toi_compress_bytes_out,
                  (pages_in - pages_out) * 100 / pages_in);
        return len;
}

/*
 * toi_compress_compression_memory_needed
 *
 * Tell the caller how much memory we need to operate during hibernate/resume.
 * Returns: Unsigned long. Maximum number of bytes of memory required for
 * operation.
 */
static int toi_compress_memory_needed(void)
{
        return 2 * PAGE_SIZE;
}

static int toi_compress_storage_needed(void)
{
        return 2 * sizeof(unsigned long) + 2 * sizeof(int) +
                strlen(toi_compressor_name) + 1;
}

/*
 * toi_compress_save_config_info
 * @buffer: Pointer to a buffer of size PAGE_SIZE.
 *
 * Save informaton needed when reloading the image at resume time.
 * Returns: Number of bytes used for saving our data.
 */
static int toi_compress_save_config_info(char *buffer)
{
        int len = strlen(toi_compressor_name) + 1, offset = 0;

        *((unsigned long *) buffer) = toi_compress_bytes_in;
        offset += sizeof(unsigned long);
        *((unsigned long *) (buffer + offset)) = toi_compress_bytes_out;
        offset += sizeof(unsigned long);
        *((int *) (buffer + offset)) = toi_expected_compression;
        offset += sizeof(int);
        *((int *) (buffer + offset)) = len;
        offset += sizeof(int);
        strncpy(buffer + offset, toi_compressor_name, len);
        return offset + len;
}

/* toi_compress_load_config_info
 * @buffer: Pointer to the start of the data.
 * @size: Number of bytes that were saved.
 *
 * Description:        Reload information needed for decompressing the image at
 * resume time.
 */
static void toi_compress_load_config_info(char *buffer, int size)
{
        int len, offset = 0;

        toi_compress_bytes_in = *((unsigned long *) buffer);
        offset += sizeof(unsigned long);
        toi_compress_bytes_out = *((unsigned long *) (buffer + offset));
        offset += sizeof(unsigned long);
        toi_expected_compression = *((int *) (buffer + offset));
        offset += sizeof(int);
        len = *((int *) (buffer + offset));
        offset += sizeof(int);
        strncpy(toi_compressor_name, buffer + offset, len);
}

static void toi_compress_pre_atomic_restore(struct toi_boot_kernel_data *bkd)
{
        bkd->compress_bytes_in = toi_compress_bytes_in;
        bkd->compress_bytes_out = toi_compress_bytes_out;
}

static void toi_compress_post_atomic_restore(struct toi_boot_kernel_data *bkd)
{
        toi_compress_bytes_in = bkd->compress_bytes_in;
        toi_compress_bytes_out = bkd->compress_bytes_out;
}

/*
 * toi_expected_compression_ratio
 *
 * Description:        Returns the expected ratio between data passed into this module
 *                 and the amount of data output when writing.
 * Returns:        100 if the module is disabled. Otherwise the value set by the
 *                 user via our sysfs entry.
 */

static int toi_compress_expected_ratio(void)
{
        if (!toi_compression_ops.enabled)
                return 100;
        else
                return 100 - toi_expected_compression;
}

/*
 * data for our sysfs entries.
 */
static struct toi_sysfs_data sysfs_params[] = {
        SYSFS_INT("expected_compression", SYSFS_RW, &toi_expected_compression,
                        0, 99, 0, NULL),
        SYSFS_INT("enabled", SYSFS_RW, &toi_compression_ops.enabled, 0, 1, 0,
                        NULL),
        SYSFS_STRING("algorithm", SYSFS_RW, toi_compressor_name, 31, 0, NULL),
};

/*
 * Ops structure.
 */
static struct toi_module_ops toi_compression_ops = {
        .type                        = FILTER_MODULE,
        .name                        = "compression",
        .directory                = "compression",
        .module                        = THIS_MODULE,
        .initialise                = toi_compress_init,
        .memory_needed                 = toi_compress_memory_needed,
        .print_debug_info        = toi_compress_print_debug_stats,
        .save_config_info        = toi_compress_save_config_info,
        .load_config_info        = toi_compress_load_config_info,
        .storage_needed                = toi_compress_storage_needed,
        .expected_compression        = toi_compress_expected_ratio,

        .pre_atomic_restore        = toi_compress_pre_atomic_restore,
        .post_atomic_restore        = toi_compress_post_atomic_restore,

        .rw_init                = toi_compress_rw_init,
        .rw_cleanup                = toi_compress_rw_cleanup,

        .write_page                = toi_compress_write_page,
        .read_page                = toi_compress_read_page,

        .sysfs_data                = sysfs_params,
        .num_sysfs_entries        = sizeof(sysfs_params) /
                sizeof(struct toi_sysfs_data),
};

/* ---- Registration ---- */

static __init int toi_compress_load(void)
{
        return toi_register_module(&toi_compression_ops);
}

late_initcall(toi_compress_load);