/*
 * RAM Oops/Panic logger
 *
 * Copyright (C) 2010 Marco Stornelli <marco.stornelli@gmail.com>
 * Copyright (C) 2011 Kees Cook <keescook@chromium.org>
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/version.h>
#include <linux/pstore.h>
#include <linux/time.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/compiler.h>
#include <linux/pstore_ram.h>

#define RAMOOPS_KERNMSG_HDR "===="
#define MIN_MEM_SIZE 4096UL

static ulong record_size = MIN_MEM_SIZE;
module_param(record_size, ulong, 0400);
MODULE_PARM_DESC(record_size,
                "size of each dump done on oops/panic");

static ulong ramoops_console_size = MIN_MEM_SIZE;
module_param_named(console_size, ramoops_console_size, ulong, 0400);
MODULE_PARM_DESC(console_size, "size of kernel console log");

static ulong ramoops_ftrace_size = MIN_MEM_SIZE;
module_param_named(ftrace_size, ramoops_ftrace_size, ulong, 0400);
MODULE_PARM_DESC(ftrace_size, "size of ftrace log");

static ulong mem_address;
module_param(mem_address, ulong, 0400);
MODULE_PARM_DESC(mem_address,
                "start of reserved RAM used to store oops/panic logs");

static ulong mem_size;
module_param(mem_size, ulong, 0400);
MODULE_PARM_DESC(mem_size,
                "size of reserved RAM used to store oops/panic logs");

static int dump_oops = 1;
module_param(dump_oops, int, 0600);
MODULE_PARM_DESC(dump_oops,
                "set to 1 to dump oopses, 0 to only dump panics (default 1)");

static int ramoops_ecc;
module_param_named(ecc, ramoops_ecc, int, 0600);
MODULE_PARM_DESC(ramoops_ecc,
                "if non-zero, the option enables ECC support and specifies "
                "ECC buffer size in bytes (1 is a special value, means 16 "
                "bytes ECC)");

struct ramoops_context {
        struct persistent_ram_zone **przs;
        struct persistent_ram_zone *cprz;
        struct persistent_ram_zone *fprz;
        phys_addr_t phys_addr;
        unsigned long size;
        size_t record_size;
        size_t console_size;
        size_t ftrace_size;
        int dump_oops;
        int ecc_size;
        unsigned int max_dump_cnt;
        unsigned int dump_write_cnt;
        unsigned int dump_read_cnt;
        unsigned int console_read_cnt;
        unsigned int ftrace_read_cnt;
        struct pstore_info pstore;
};

static struct platform_device *dummy;
static struct ramoops_platform_data *dummy_data;

static int ramoops_pstore_open(struct pstore_info *psi)
{
        struct ramoops_context *cxt = psi->data;

        cxt->dump_read_cnt = 0;
        cxt->console_read_cnt = 0;
        return 0;
}

static struct persistent_ram_zone *
ramoops_get_next_prz(struct persistent_ram_zone *przs[], uint *c, uint max,
                     u64 *id,
                     enum pstore_type_id *typep, enum pstore_type_id type,
                     bool update)
{
        struct persistent_ram_zone *prz;
        int i = (*c)++;

        if (i >= max)
                return NULL;

        prz = przs[i];

        if (update) {
                /* Update old/shadowed buffer. */
                persistent_ram_save_old(prz);
                if (!persistent_ram_old_size(prz))
                        return NULL;
        }

        *typep = type;
        *id = i;

        return prz;
}

static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
                                   struct timespec *time,
                                   char **buf,
                                   struct pstore_info *psi)
{
        ssize_t size;
        struct ramoops_context *cxt = psi->data;
        struct persistent_ram_zone *prz;

        prz = ramoops_get_next_prz(cxt->przs, &cxt->dump_read_cnt,
                                   cxt->max_dump_cnt, id, type,
                                   PSTORE_TYPE_DMESG, 1);
        if (!prz)
                prz = ramoops_get_next_prz(&cxt->cprz, &cxt->console_read_cnt,
                                           1, id, type, PSTORE_TYPE_CONSOLE, 0);
        if (!prz)
                prz = ramoops_get_next_prz(&cxt->fprz, &cxt->ftrace_read_cnt,
                                           1, id, type, PSTORE_TYPE_FTRACE, 0);
        if (!prz)
                return 0;

        /* TODO(kees): Bogus time for the moment. */
        time->tv_sec = 0;
        time->tv_nsec = 0;

        size = persistent_ram_old_size(prz);
        *buf = kmalloc(size, GFP_KERNEL);
        if (*buf == NULL)
                return -ENOMEM;
        memcpy(*buf, persistent_ram_old(prz), size);

        return size;
}

static size_t ramoops_write_kmsg_hdr(struct persistent_ram_zone *prz)
{
        char *hdr;
        struct timeval timestamp;
        size_t len;

        do_gettimeofday(&timestamp);
        hdr = kasprintf(GFP_ATOMIC, RAMOOPS_KERNMSG_HDR "%lu.%lu\n",
                (long)timestamp.tv_sec, (long)timestamp.tv_usec);
        WARN_ON_ONCE(!hdr);
        len = hdr ? strlen(hdr) : 0;
        persistent_ram_write(prz, hdr, len);
        kfree(hdr);

        return len;
}

static int notrace ramoops_pstore_write_buf(enum pstore_type_id type,
                                            enum kmsg_dump_reason reason,
                                            u64 *id, unsigned int part,
                                            const char *buf, size_t size,
                                            struct pstore_info *psi)
{
        struct ramoops_context *cxt = psi->data;
        struct persistent_ram_zone *prz = cxt->przs[cxt->dump_write_cnt];
        size_t hlen;

        if (type == PSTORE_TYPE_CONSOLE) {
                if (!cxt->cprz)
                        return -ENOMEM;
                persistent_ram_write(cxt->cprz, buf, size);
                return 0;
        } else if (type == PSTORE_TYPE_FTRACE) {
                if (!cxt->fprz)
                        return -ENOMEM;
                persistent_ram_write(cxt->fprz, buf, size);
                return 0;
        }

        if (type != PSTORE_TYPE_DMESG)
                return -EINVAL;

        /* Out of the various dmesg dump types, ramoops is currently designed
         * to only store crash logs, rather than storing general kernel logs.
         */
        if (reason != KMSG_DUMP_OOPS &&
            reason != KMSG_DUMP_PANIC)
                return -EINVAL;

        /* Skip Oopes when configured to do so. */
        if (reason == KMSG_DUMP_OOPS && !cxt->dump_oops)
                return -EINVAL;

        /* Explicitly only take the first part of any new crash.
         * If our buffer is larger than kmsg_bytes, this can never happen,
         * and if our buffer is smaller than kmsg_bytes, we don't want the
         * report split across multiple records.
         */
        if (part != 1)
                return -ENOSPC;

        hlen = ramoops_write_kmsg_hdr(prz);
        if (size + hlen > prz->buffer_size)
                size = prz->buffer_size - hlen;
        persistent_ram_write(prz, buf, size);

        cxt->dump_write_cnt = (cxt->dump_write_cnt + 1) % cxt->max_dump_cnt;

        return 0;
}

static int ramoops_pstore_erase(enum pstore_type_id type, u64 id,
                                struct pstore_info *psi)
{
        struct ramoops_context *cxt = psi->data;
        struct persistent_ram_zone *prz;

        switch (type) {
        case PSTORE_TYPE_DMESG:
                if (id >= cxt->max_dump_cnt)
                        return -EINVAL;
                prz = cxt->przs[id];
                break;
        case PSTORE_TYPE_CONSOLE:
                prz = cxt->cprz;
                break;
        case PSTORE_TYPE_FTRACE:
                prz = cxt->fprz;
                break;
        default:
                return -EINVAL;
        }

        persistent_ram_free_old(prz);
        persistent_ram_zap(prz);

        return 0;
}

static struct ramoops_context oops_cxt = {
        .pstore = {
                .owner  = THIS_MODULE,
                .name   = "ramoops",
                .open   = ramoops_pstore_open,
                .read   = ramoops_pstore_read,
                .write_buf      = ramoops_pstore_write_buf,
                .erase  = ramoops_pstore_erase,
        },
};

static void ramoops_free_przs(struct ramoops_context *cxt)
{
        int i;

        if (!cxt->przs)
                return;

        for (i = 0; !IS_ERR_OR_NULL(cxt->przs[i]); i++)
                persistent_ram_free(cxt->przs[i]);
        kfree(cxt->przs);
}

static int ramoops_init_przs(struct device *dev, struct ramoops_context *cxt,
                              phys_addr_t *paddr, size_t dump_mem_sz)
{
        int err = -ENOMEM;
        int i;

        if (!cxt->record_size)
                return 0;

        cxt->max_dump_cnt = dump_mem_sz / cxt->record_size;
        if (!cxt->max_dump_cnt)
                return -ENOMEM;

        cxt->przs = kzalloc(sizeof(*cxt->przs) * cxt->max_dump_cnt,
                             GFP_KERNEL);
        if (!cxt->przs) {
                dev_err(dev, "failed to initialize a prz array for dumps\n");
                return -ENOMEM;
        }

        for (i = 0; i < cxt->max_dump_cnt; i++) {
                size_t sz = cxt->record_size;

                cxt->przs[i] = persistent_ram_new(*paddr, sz, 0, cxt->ecc_size);
                if (IS_ERR(cxt->przs[i])) {
                        err = PTR_ERR(cxt->przs[i]);
                        dev_err(dev, "failed to request mem region (0x%zx@0x%llx): %d\n",
                                sz, (unsigned long long)*paddr, err);
                        goto fail_prz;
                }
                *paddr += sz;
        }

        return 0;
fail_prz:
        ramoops_free_przs(cxt);
        return err;
}

static int ramoops_init_prz(struct device *dev, struct ramoops_context *cxt,
                            struct persistent_ram_zone **prz,
                            phys_addr_t *paddr, size_t sz, u32 sig)
{
        if (!sz)
                return 0;

        if (*paddr + sz > *paddr + cxt->size)
                return -ENOMEM;

        *prz = persistent_ram_new(*paddr, sz, sig, cxt->ecc_size);
        if (IS_ERR(*prz)) {
                int err = PTR_ERR(*prz);

                dev_err(dev, "failed to request mem region (0x%zx@0x%llx): %d\n",
                        sz, (unsigned long long)*paddr, err);
                return err;
        }

        persistent_ram_zap(*prz);

        *paddr += sz;

        return 0;
}

static int __devinit ramoops_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct ramoops_platform_data *pdata = pdev->dev.platform_data;
        struct ramoops_context *cxt = &oops_cxt;
        size_t dump_mem_sz;
        phys_addr_t paddr;
        int err = -EINVAL;

        /* Only a single ramoops area allowed at a time, so fail extra
         * probes.
         */
        if (cxt->max_dump_cnt)
                goto fail_out;

        if (!pdata->mem_size || (!pdata->record_size && !pdata->console_size &&
                        !pdata->ftrace_size)) {
                pr_err("The memory size and the record/console size must be "
                        "non-zero\n");
                goto fail_out;
        }

        pdata->mem_size = rounddown_pow_of_two(pdata->mem_size);
        pdata->record_size = rounddown_pow_of_two(pdata->record_size);
        pdata->console_size = rounddown_pow_of_two(pdata->console_size);
        pdata->ftrace_size = rounddown_pow_of_two(pdata->ftrace_size);

        cxt->dump_read_cnt = 0;
        cxt->size = pdata->mem_size;
        cxt->phys_addr = pdata->mem_address;
        cxt->record_size = pdata->record_size;
        cxt->console_size = pdata->console_size;
        cxt->ftrace_size = pdata->ftrace_size;
        cxt->dump_oops = pdata->dump_oops;
        cxt->ecc_size = pdata->ecc_size;

        paddr = cxt->phys_addr;

        dump_mem_sz = cxt->size - cxt->console_size - cxt->ftrace_size;
        err = ramoops_init_przs(dev, cxt, &paddr, dump_mem_sz);
        if (err)
                goto fail_out;

        err = ramoops_init_prz(dev, cxt, &cxt->cprz, &paddr,
                               cxt->console_size, 0);
        if (err)
                goto fail_init_cprz;

        err = ramoops_init_prz(dev, cxt, &cxt->fprz, &paddr, cxt->ftrace_size,
                               LINUX_VERSION_CODE);
        if (err)
                goto fail_init_fprz;

        if (!cxt->przs && !cxt->cprz && !cxt->fprz) {
                pr_err("memory size too small, minimum is %zu\n",
                        cxt->console_size + cxt->record_size +
                        cxt->ftrace_size);
                goto fail_cnt;
        }

        cxt->pstore.data = cxt;
        /*
         * Console can handle any buffer size, so prefer LOG_LINE_MAX. If we
         * have to handle dumps, we must have at least record_size buffer. And
         * for ftrace, bufsize is irrelevant (if bufsize is 0, buf will be
         * ZERO_SIZE_PTR).
         */
        if (cxt->console_size)
                cxt->pstore.bufsize = 1024; /* LOG_LINE_MAX */
        cxt->pstore.bufsize = max(cxt->record_size, cxt->pstore.bufsize);
        cxt->pstore.buf = kmalloc(cxt->pstore.bufsize, GFP_KERNEL);
        spin_lock_init(&cxt->pstore.buf_lock);
        if (!cxt->pstore.buf) {
                pr_err("cannot allocate pstore buffer\n");
                goto fail_clear;
        }

        err = pstore_register(&cxt->pstore);
        if (err) {
                pr_err("registering with pstore failed\n");
                goto fail_buf;
        }

        /*
         * Update the module parameter variables as well so they are visible
         * through /sys/module/ramoops/parameters/
         */
        mem_size = pdata->mem_size;
        mem_address = pdata->mem_address;
        record_size = pdata->record_size;
        dump_oops = pdata->dump_oops;

        pr_info("attached 0x%lx@0x%llx, ecc: %d\n",
                cxt->size, (unsigned long long)cxt->phys_addr,
                cxt->ecc_size);

        return 0;

fail_buf:
        kfree(cxt->pstore.buf);
fail_clear:
        cxt->pstore.bufsize = 0;
        cxt->max_dump_cnt = 0;
fail_cnt:
        kfree(cxt->fprz);
fail_init_fprz:
        kfree(cxt->cprz);
fail_init_cprz:
        ramoops_free_przs(cxt);
fail_out:
        return err;
}

static int __exit ramoops_remove(struct platform_device *pdev)
{
#if 0
        /* TODO(kees): We cannot unload ramoops since pstore doesn't support
         * unregistering yet.
         */
        struct ramoops_context *cxt = &oops_cxt;

        iounmap(cxt->virt_addr);
        release_mem_region(cxt->phys_addr, cxt->size);
        cxt->max_dump_cnt = 0;

        /* TODO(kees): When pstore supports unregistering, call it here. */
        kfree(cxt->pstore.buf);
        cxt->pstore.bufsize = 0;

        return 0;
#endif
        return -EBUSY;
}

static struct platform_driver ramoops_driver = {
        .probe          = ramoops_probe,
        .remove         = __exit_p(ramoops_remove),
        .driver         = {
                .name   = "ramoops",
                .owner  = THIS_MODULE,
        },
};

static void ramoops_register_dummy(void)
{
        if (!mem_size)
                return;

        pr_info("using module parameters\n");

        dummy_data = kzalloc(sizeof(*dummy_data), GFP_KERNEL);
        if (!dummy_data) {
                pr_info("could not allocate pdata\n");
                return;
        }

        dummy_data->mem_size = mem_size;
        dummy_data->mem_address = mem_address;
        dummy_data->record_size = record_size;
        dummy_data->console_size = ramoops_console_size;
        dummy_data->ftrace_size = ramoops_ftrace_size;
        dummy_data->dump_oops = dump_oops;
        /*
         * For backwards compatibility ramoops.ecc=1 means 16 bytes ECC
         * (using 1 byte for ECC isn't much of use anyway).
         */
        dummy_data->ecc_size = ramoops_ecc == 1 ? 16 : ramoops_ecc;

        dummy = platform_device_register_data(NULL, "ramoops", -1,
                        dummy_data, sizeof(struct ramoops_platform_data));
        if (IS_ERR(dummy)) {
                pr_info("could not create platform device: %ld\n",
                        PTR_ERR(dummy));
        }
}

static int __init ramoops_init(void)
{
        ramoops_register_dummy();
        return platform_driver_register(&ramoops_driver);
}
postcore_initcall(ramoops_init);

static void __exit ramoops_exit(void)
{
        platform_driver_unregister(&ramoops_driver);
        platform_device_unregister(dummy);
        kfree(dummy_data);
}
module_exit(ramoops_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Marco Stornelli <marco.stornelli@gmail.com>");
MODULE_DESCRIPTION("RAM Oops/Panic logger/driver");