/*
 * Remote Processor Framework Elf loader
 *
 * Copyright (C) 2011 Texas Instruments, Inc.
 * Copyright (C) 2011 Google, Inc.
 *
 * Ohad Ben-Cohen <ohad@wizery.com>
 * Brian Swetland <swetland@google.com>
 * Mark Grosen <mgrosen@ti.com>
 * Fernando Guzman Lugo <fernando.lugo@ti.com>
 * Suman Anna <s-anna@ti.com>
 * Robert Tivy <rtivy@ti.com>
 * Armando Uribe De Leon <x0095078@ti.com>
 * Sjur Brændeland <sjur.brandeland@stericsson.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

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

#include <linux/module.h>
#include <linux/firmware.h>
#include <linux/remoteproc.h>
#include <linux/elf.h>

#include "remoteproc_internal.h"

/**
 * rproc_elf_sanity_check() - Sanity Check ELF firmware image
 * @rproc: the remote processor handle
 * @fw: the ELF firmware image
 *
 * Make sure this fw image is sane.
 */
static int
rproc_elf_sanity_check(struct rproc *rproc, const struct firmware *fw)
{
        const char *name = rproc->firmware;
        struct device *dev = &rproc->dev;
        struct elf32_hdr *ehdr;
        char class;

        if (!fw) {
                dev_err(dev, "failed to load %s\n", name);
                return -EINVAL;
        }

        if (fw->size < sizeof(struct elf32_hdr)) {
                dev_err(dev, "Image is too small\n");
                return -EINVAL;
        }

        ehdr = (struct elf32_hdr *)fw->data;

        /* We only support ELF32 at this point */
        class = ehdr->e_ident[EI_CLASS];
        if (class != ELFCLASS32) {
                dev_err(dev, "Unsupported class: %d\n", class);
                return -EINVAL;
        }

        /* We assume the firmware has the same endianness as the host */
# ifdef __LITTLE_ENDIAN
        if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB) {
# else /* BIG ENDIAN */
        if (ehdr->e_ident[EI_DATA] != ELFDATA2MSB) {
# endif
                dev_err(dev, "Unsupported firmware endianness\n");
                return -EINVAL;
        }

        if (fw->size < ehdr->e_shoff + sizeof(struct elf32_shdr)) {
                dev_err(dev, "Image is too small\n");
                return -EINVAL;
        }

        if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG)) {
                dev_err(dev, "Image is corrupted (bad magic)\n");
                return -EINVAL;
        }

        if (ehdr->e_phnum == 0) {
                dev_err(dev, "No loadable segments\n");
                return -EINVAL;
        }

        if (ehdr->e_phoff > fw->size) {
                dev_err(dev, "Firmware size is too small\n");
                return -EINVAL;
        }

        return 0;
}

/**
 * rproc_elf_get_boot_addr() - Get rproc's boot address.
 * @rproc: the remote processor handle
 * @fw: the ELF firmware image
 *
 * This function returns the entry point address of the ELF
 * image.
 *
 * Note that the boot address is not a configurable property of all remote
 * processors. Some will always boot at a specific hard-coded address.
 */
static
u32 rproc_elf_get_boot_addr(struct rproc *rproc, const struct firmware *fw)
{
        struct elf32_hdr *ehdr  = (struct elf32_hdr *)fw->data;

        return ehdr->e_entry;
}

/**
 * rproc_elf_load_segments() - load firmware segments to memory
 * @rproc: remote processor which will be booted using these fw segments
 * @fw: the ELF firmware image
 *
 * This function loads the firmware segments to memory, where the remote
 * processor expects them.
 *
 * Some remote processors will expect their code and data to be placed
 * in specific device addresses, and can't have them dynamically assigned.
 *
 * We currently support only those kind of remote processors, and expect
 * the program header's paddr member to contain those addresses. We then go
 * through the physically contiguous "carveout" memory regions which we
 * allocated (and mapped) earlier on behalf of the remote processor,
 * and "translate" device address to kernel addresses, so we can copy the
 * segments where they are expected.
 *
 * Currently we only support remote processors that required carveout
 * allocations and got them mapped onto their iommus. Some processors
 * might be different: they might not have iommus, and would prefer to
 * directly allocate memory for every segment/resource. This is not yet
 * supported, though.
 */
static int
rproc_elf_load_segments(struct rproc *rproc, const struct firmware *fw)
{
        struct device *dev = &rproc->dev;
        struct elf32_hdr *ehdr;
        struct elf32_phdr *phdr;
        int i, ret = 0;
        const u8 *elf_data = fw->data;

        ehdr = (struct elf32_hdr *)elf_data;
        phdr = (struct elf32_phdr *)(elf_data + ehdr->e_phoff);

        /* go through the available ELF segments */
        for (i = 0; i < ehdr->e_phnum; i++, phdr++) {
                u32 da = phdr->p_paddr;
                u32 memsz = phdr->p_memsz;
                u32 filesz = phdr->p_filesz;
                u32 offset = phdr->p_offset;
                void *ptr;

                if (phdr->p_type != PT_LOAD)
                        continue;

                dev_dbg(dev, "phdr: type %d da 0x%x memsz 0x%x filesz 0x%x\n",
                                        phdr->p_type, da, memsz, filesz);

                if (filesz > memsz) {
                        dev_err(dev, "bad phdr filesz 0x%x memsz 0x%x\n",
                                                        filesz, memsz);
                        ret = -EINVAL;
                        break;
                }

                if (offset + filesz > fw->size) {
                        dev_err(dev, "truncated fw: need 0x%x avail 0x%zx\n",
                                        offset + filesz, fw->size);
                        ret = -EINVAL;
                        break;
                }

                /* grab the kernel address for this device address */
                ptr = rproc_da_to_va(rproc, da, memsz);
                if (!ptr) {
                        dev_err(dev, "bad phdr da 0x%x mem 0x%x\n", da, memsz);
                        ret = -EINVAL;
                        break;
                }

                /* put the segment where the remote processor expects it */
                if (phdr->p_filesz)
                        memcpy(ptr, elf_data + phdr->p_offset, filesz);

                /*
                 * Zero out remaining memory for this segment.
                 *
                 * This isn't strictly required since dma_alloc_coherent already
                 * did this for us. albeit harmless, we may consider removing
                 * this.
                 */
                if (memsz > filesz)
                        memset(ptr + filesz, 0, memsz - filesz);
        }

        return ret;
}

/**
 * rproc_elf_find_rsc_table() - find the resource table
 * @rproc: the rproc handle
 * @fw: the ELF firmware image
 * @tablesz: place holder for providing back the table size
 *
 * This function finds the resource table inside the remote processor's
 * firmware. It is used both upon the registration of @rproc (in order
 * to look for and register the supported virito devices), and when the
 * @rproc is booted.
 *
 * Returns the pointer to the resource table if it is found, and write its
 * size into @tablesz. If a valid table isn't found, NULL is returned
 * (and @tablesz isn't set).
 */
static struct resource_table *
rproc_elf_find_rsc_table(struct rproc *rproc, const struct firmware *fw,
                                                        int *tablesz)
{
        struct elf32_hdr *ehdr;
        struct elf32_shdr *shdr;
        const char *name_table;
        struct device *dev = &rproc->dev;
        struct resource_table *table = NULL;
        int i;
        const u8 *elf_data = fw->data;

        ehdr = (struct elf32_hdr *)elf_data;
        shdr = (struct elf32_shdr *)(elf_data + ehdr->e_shoff);
        name_table = elf_data + shdr[ehdr->e_shstrndx].sh_offset;

        /* look for the resource table and handle it */
        for (i = 0; i < ehdr->e_shnum; i++, shdr++) {
                int size = shdr->sh_size;
                int offset = shdr->sh_offset;

                if (strcmp(name_table + shdr->sh_name, ".resource_table"))
                        continue;

                table = (struct resource_table *)(elf_data + offset);

                /* make sure we have the entire table */
                if (offset + size > fw->size) {
                        dev_err(dev, "resource table truncated\n");
                        return NULL;
                }

                /* make sure table has at least the header */
                if (sizeof(struct resource_table) > size) {
                        dev_err(dev, "header-less resource table\n");
                        return NULL;
                }

                /* we don't support any version beyond the first */
                if (table->ver != 1) {
                        dev_err(dev, "unsupported fw ver: %d\n", table->ver);
                        return NULL;
                }

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

                /* make sure the offsets array isn't truncated */
                if (table->num * sizeof(table->offset[0]) +
                                sizeof(struct resource_table) > size) {
                        dev_err(dev, "resource table incomplete\n");
                        return NULL;
                }

                *tablesz = shdr->sh_size;
                break;
        }

        return table;
}

const struct rproc_fw_ops rproc_elf_fw_ops = {
        .load = rproc_elf_load_segments,
        .find_rsc_table = rproc_elf_find_rsc_table,
        .sanity_check = rproc_elf_sanity_check,
        .get_boot_addr = rproc_elf_get_boot_addr
};