// SPDX-License-Identifier: GPL-2.0-only
/*
 * RAM Oops/Panic logger
 *
 * Copyright (C) 2010 Marco Stornelli <marco.stornelli@gmail.com>
 * Copyright (C) 2011 Kees Cook <keescook@chromium.org>
 */

#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/io.h>
#include <linux/ioport.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/compiler.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/mm.h>

#include "internal.h"
#include "ram_internal.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 ramoops_pmsg_size = MIN_MEM_SIZE;
module_param_named(pmsg_size, ramoops_pmsg_size, ulong, 0400);
MODULE_PARM_DESC(pmsg_size, "size of user space message log");

static unsigned long long mem_address;
module_param_hw(mem_address, ullong, other, 0400);
MODULE_PARM_DESC(mem_address,
                "start of reserved RAM used to store oops/panic logs");

static char *mem_name;
module_param_named(mem_name, mem_name, charp, 0400);
MODULE_PARM_DESC(mem_name, "name of kernel param that holds addr");

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 unsigned int mem_type;
module_param(mem_type, uint, 0400);
MODULE_PARM_DESC(mem_type,
                "memory type: 0=write-combined (default), 1=unbuffered, 2=cached");

static int ramoops_max_reason = -1;
module_param_named(max_reason, ramoops_max_reason, int, 0400);
MODULE_PARM_DESC(max_reason,
                 "maximum reason for kmsg dump (default 2: Oops and Panic) ");

static int ramoops_ecc;
module_param_named(ecc, ramoops_ecc, int, 0400);
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)");

static int ramoops_dump_oops = -1;
module_param_named(dump_oops, ramoops_dump_oops, int, 0400);
MODULE_PARM_DESC(dump_oops,
                 "(deprecated: use max_reason instead) set to 1 to dump oopses & panics, 0 to only dump panics");

struct ramoops_context {
        struct persistent_ram_zone **dprzs;     /* Oops dump zones */
        struct persistent_ram_zone *cprz;       /* Console zone */
        struct persistent_ram_zone **fprzs;     /* Ftrace zones */
        struct persistent_ram_zone *mprz;       /* PMSG zone */
        phys_addr_t phys_addr;
        unsigned long size;
        unsigned int memtype;
        size_t record_size;
        size_t console_size;
        size_t ftrace_size;
        size_t pmsg_size;
        u32 flags;
        struct persistent_ram_ecc_info ecc_info;
        unsigned int max_dump_cnt;
        unsigned int dump_write_cnt;
        /* _read_cnt need clear on ramoops_pstore_open */
        unsigned int dump_read_cnt;
        unsigned int console_read_cnt;
        unsigned int max_ftrace_cnt;
        unsigned int ftrace_read_cnt;
        unsigned int pmsg_read_cnt;
        struct pstore_info pstore;
};

static struct platform_device *dummy;

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;
        cxt->ftrace_read_cnt = 0;
        cxt->pmsg_read_cnt = 0;
        return 0;
}

static struct persistent_ram_zone *
ramoops_get_next_prz(struct persistent_ram_zone *przs[], int id,
                     struct pstore_record *record)
{
        struct persistent_ram_zone *prz;

        /* Give up if we never existed or have hit the end. */
        if (!przs)
                return NULL;

        prz = przs[id];
        if (!prz)
                return NULL;

        /* Update old/shadowed buffer. */
        if (prz->type == PSTORE_TYPE_DMESG)
                persistent_ram_save_old(prz);

        if (!persistent_ram_old_size(prz))
                return NULL;

        record->type = prz->type;
        record->id = id;

        return prz;
}

static int ramoops_read_kmsg_hdr(char *buffer, struct timespec64 *time,
                                  bool *compressed)
{
        char data_type;
        int header_length = 0;

        if (sscanf(buffer, RAMOOPS_KERNMSG_HDR "%lld.%lu-%c\n%n",
                   (time64_t *)&time->tv_sec, &time->tv_nsec, &data_type,
                   &header_length) == 3) {
                time->tv_nsec *= 1000;
                if (data_type == 'C')
                        *compressed = true;
                else
                        *compressed = false;
        } else if (sscanf(buffer, RAMOOPS_KERNMSG_HDR "%lld.%lu\n%n",
                          (time64_t *)&time->tv_sec, &time->tv_nsec,
                          &header_length) == 2) {
                time->tv_nsec *= 1000;
                *compressed = false;
        } else {
                time->tv_sec = 0;
                time->tv_nsec = 0;
                *compressed = false;
        }
        return header_length;
}

static bool prz_ok(struct persistent_ram_zone *prz)
{
        return !!prz && !!(persistent_ram_old_size(prz) +
                           persistent_ram_ecc_string(prz, NULL, 0));
}

static ssize_t ramoops_pstore_read(struct pstore_record *record)
{
        ssize_t size = 0;
        struct ramoops_context *cxt = record->psi->data;
        struct persistent_ram_zone *prz = NULL;
        int header_length = 0;
        bool free_prz = false;

        /*
         * Ramoops headers provide time stamps for PSTORE_TYPE_DMESG, but
         * PSTORE_TYPE_CONSOLE and PSTORE_TYPE_FTRACE don't currently have
         * valid time stamps, so it is initialized to zero.
         */
        record->time.tv_sec = 0;
        record->time.tv_nsec = 0;
        record->compressed = false;

        /* Find the next valid persistent_ram_zone for DMESG */
        while (cxt->dump_read_cnt < cxt->max_dump_cnt && !prz) {
                prz = ramoops_get_next_prz(cxt->dprzs, cxt->dump_read_cnt++,
                                           record);
                if (!prz_ok(prz))
                        continue;
                header_length = ramoops_read_kmsg_hdr(persistent_ram_old(prz),
                                                      &record->time,
                                                      &record->compressed);
                /* Clear and skip this DMESG record if it has no valid header */
                if (!header_length) {
                        persistent_ram_free_old(prz);
                        persistent_ram_zap(prz);
                        prz = NULL;
                }
        }

        if (!prz_ok(prz) && !cxt->console_read_cnt++)
                prz = ramoops_get_next_prz(&cxt->cprz, 0 /* single */, record);

        if (!prz_ok(prz) && !cxt->pmsg_read_cnt++)
                prz = ramoops_get_next_prz(&cxt->mprz, 0 /* single */, record);

        /* ftrace is last since it may want to dynamically allocate memory. */
        if (!prz_ok(prz)) {
                if (!(cxt->flags & RAMOOPS_FLAG_FTRACE_PER_CPU) &&
                    !cxt->ftrace_read_cnt++) {
                        prz = ramoops_get_next_prz(cxt->fprzs, 0 /* single */,
                                                   record);
                } else {
                        /*
                         * Build a new dummy record which combines all the
                         * per-cpu records including metadata and ecc info.
                         */
                        struct persistent_ram_zone *tmp_prz, *prz_next;

                        tmp_prz = kzalloc_obj(struct persistent_ram_zone);
                        if (!tmp_prz)
                                return -ENOMEM;
                        prz = tmp_prz;
                        free_prz = true;

                        while (cxt->ftrace_read_cnt < cxt->max_ftrace_cnt) {
                                prz_next = ramoops_get_next_prz(cxt->fprzs,
                                                cxt->ftrace_read_cnt++, record);

                                if (!prz_ok(prz_next))
                                        continue;

                                tmp_prz->ecc_info = prz_next->ecc_info;
                                tmp_prz->corrected_bytes +=
                                                prz_next->corrected_bytes;
                                tmp_prz->bad_blocks += prz_next->bad_blocks;

                                size = pstore_ftrace_combine_log(
                                                &tmp_prz->old_log,
                                                &tmp_prz->old_log_size,
                                                prz_next->old_log,
                                                prz_next->old_log_size);
                                if (size)
                                        goto out;
                        }
                        record->id = 0;
                }
        }

        if (!prz_ok(prz)) {
                size = 0;
                goto out;
        }

        size = persistent_ram_old_size(prz) - header_length;

        /* ECC correction notice */
        record->ecc_notice_size = persistent_ram_ecc_string(prz, NULL, 0);

        record->buf = kvzalloc(size + record->ecc_notice_size + 1, GFP_KERNEL);
        if (record->buf == NULL) {
                size = -ENOMEM;
                goto out;
        }

        memcpy(record->buf, (char *)persistent_ram_old(prz) + header_length,
               size);

        persistent_ram_ecc_string(prz, record->buf + size,
                                  record->ecc_notice_size + 1);

out:
        if (free_prz) {
                kvfree(prz->old_log);
                kfree(prz);
        }

        return size;
}

static size_t ramoops_write_kmsg_hdr(struct persistent_ram_zone *prz,
                                     struct pstore_record *record)
{
        char hdr[36]; /* "===="(4), %lld(20), "."(1), %06lu(6), "-%c\n"(3) */
        size_t len;

        len = scnprintf(hdr, sizeof(hdr),
                RAMOOPS_KERNMSG_HDR "%lld.%06lu-%c\n",
                (time64_t)record->time.tv_sec,
                record->time.tv_nsec / 1000,
                record->compressed ? 'C' : 'D');
        persistent_ram_write(prz, hdr, len);

        return len;
}

static int notrace ramoops_pstore_write(struct pstore_record *record)
{
        struct ramoops_context *cxt = record->psi->data;
        struct persistent_ram_zone *prz;
        size_t size, hlen;

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

                if (!cxt->fprzs)
                        return -ENOMEM;
                /*
                 * Choose zone by if we're using per-cpu buffers.
                 */
                if (cxt->flags & RAMOOPS_FLAG_FTRACE_PER_CPU)
                        zonenum = smp_processor_id();
                else
                        zonenum = 0;

                persistent_ram_write(cxt->fprzs[zonenum], record->buf,
                                     record->size);
                return 0;
        } else if (record->type == PSTORE_TYPE_PMSG) {
                pr_warn_ratelimited("PMSG shouldn't call %s\n", __func__);
                return -EINVAL;
        }

        if (record->type != PSTORE_TYPE_DMESG)
                return -EINVAL;

        /*
         * We could filter on record->reason here if we wanted to (which
         * would duplicate what happened before the "max_reason" setting
         * was added), but that would defeat the purpose of a system
         * changing printk.always_kmsg_dump, so instead log everything that
         * the kmsg dumper sends us, since it should be doing the filtering
         * based on the combination of printk.always_kmsg_dump and our
         * requested "max_reason".
         */

        /*
         * 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 (record->part != 1)
                return -ENOSPC;

        if (!cxt->dprzs)
                return -ENOSPC;

        prz = cxt->dprzs[cxt->dump_write_cnt];

        /*
         * Since this is a new crash dump, we need to reset the buffer in
         * case it still has an old dump present. Without this, the new dump
         * will get appended, which would seriously confuse anything trying
         * to check dump file contents. Specifically, ramoops_read_kmsg_hdr()
         * expects to find a dump header in the beginning of buffer data, so
         * we must to reset the buffer values, in order to ensure that the
         * header will be written to the beginning of the buffer.
         */
        persistent_ram_zap(prz);

        /* Build header and append record contents. */
        hlen = ramoops_write_kmsg_hdr(prz, record);
        if (!hlen)
                return -ENOMEM;

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

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

        return 0;
}

static int notrace ramoops_pstore_write_user(struct pstore_record *record,
                                             const char __user *buf)
{
        if (record->type == PSTORE_TYPE_PMSG) {
                struct ramoops_context *cxt = record->psi->data;

                if (!cxt->mprz)
                        return -ENOMEM;
                return persistent_ram_write_user(cxt->mprz, buf, record->size);
        }

        return -EINVAL;
}

static int ramoops_pstore_erase(struct pstore_record *record)
{
        struct ramoops_context *cxt = record->psi->data;
        struct persistent_ram_zone *prz;

        switch (record->type) {
        case PSTORE_TYPE_DMESG:
                if (record->id >= cxt->max_dump_cnt)
                        return -EINVAL;
                prz = cxt->dprzs[record->id];
                break;
        case PSTORE_TYPE_CONSOLE:
                prz = cxt->cprz;
                break;
        case PSTORE_TYPE_FTRACE:
                if (record->id >= cxt->max_ftrace_cnt)
                        return -EINVAL;
                prz = cxt->fprzs[record->id];
                break;
        case PSTORE_TYPE_PMSG:
                prz = cxt->mprz;
                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  = ramoops_pstore_write,
                .write_user     = ramoops_pstore_write_user,
                .erase  = ramoops_pstore_erase,
        },
};

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

        /* Free pmsg PRZ */
        persistent_ram_free(&cxt->mprz);

        /* Free console PRZ */
        persistent_ram_free(&cxt->cprz);

        /* Free dump PRZs */
        if (cxt->dprzs) {
                for (i = 0; i < cxt->max_dump_cnt; i++)
                        persistent_ram_free(&cxt->dprzs[i]);

                kfree(cxt->dprzs);
                cxt->dprzs = NULL;
                cxt->max_dump_cnt = 0;
        }

        /* Free ftrace PRZs */
        if (cxt->fprzs) {
                for (i = 0; i < cxt->max_ftrace_cnt; i++)
                        persistent_ram_free(&cxt->fprzs[i]);
                kfree(cxt->fprzs);
                cxt->fprzs = NULL;
                cxt->max_ftrace_cnt = 0;
        }
}

static int ramoops_init_przs(const char *name,
                             struct device *dev, struct ramoops_context *cxt,
                             struct persistent_ram_zone ***przs,
                             phys_addr_t *paddr, size_t mem_sz,
                             ssize_t record_size,
                             unsigned int *cnt, u32 sig, u32 flags)
{
        int err = -ENOMEM;
        int i;
        size_t zone_sz;
        struct persistent_ram_zone **prz_ar;

        /* Allocate nothing for 0 mem_sz or 0 record_size. */
        if (mem_sz == 0 || record_size == 0) {
                *cnt = 0;
                return 0;
        }

        /*
         * If we have a negative record size, calculate it based on
         * mem_sz / *cnt. If we have a positive record size, calculate
         * cnt from mem_sz / record_size.
         */
        if (record_size < 0) {
                if (*cnt == 0)
                        return 0;
                record_size = mem_sz / *cnt;
                if (record_size == 0) {
                        dev_err(dev, "%s record size == 0 (%zu / %u)\n",
                                name, mem_sz, *cnt);
                        goto fail;
                }
        } else {
                *cnt = mem_sz / record_size;
                if (*cnt == 0) {
                        dev_err(dev, "%s record count == 0 (%zu / %zu)\n",
                                name, mem_sz, record_size);
                        goto fail;
                }
        }

        if (*paddr + mem_sz - cxt->phys_addr > cxt->size) {
                dev_err(dev, "no room for %s mem region (0x%zx@0x%llx) in (0x%lx@0x%llx)\n",
                        name,
                        mem_sz, (unsigned long long)*paddr,
                        cxt->size, (unsigned long long)cxt->phys_addr);
                goto fail;
        }

        zone_sz = mem_sz / *cnt;
        zone_sz = ALIGN_DOWN(zone_sz, 2);
        if (!zone_sz) {
                dev_err(dev, "%s zone size == 0\n", name);
                goto fail;
        }

        prz_ar = kzalloc_objs(**przs, *cnt);
        if (!prz_ar)
                goto fail;

        for (i = 0; i < *cnt; i++) {
                char *label;

                if (*cnt == 1)
                        label = kasprintf(GFP_KERNEL, "ramoops:%s", name);
                else
                        label = kasprintf(GFP_KERNEL, "ramoops:%s(%d/%d)",
                                          name, i, *cnt - 1);
                prz_ar[i] = persistent_ram_new(*paddr, zone_sz, sig,
                                               &cxt->ecc_info,
                                               cxt->memtype, flags, label);
                kfree(label);
                if (IS_ERR(prz_ar[i])) {
                        err = PTR_ERR(prz_ar[i]);
                        dev_err(dev, "failed to request %s mem region (0x%zx@0x%llx): %d\n",
                                name, record_size,
                                (unsigned long long)*paddr, err);

                        while (i > 0) {
                                i--;
                                persistent_ram_free(&prz_ar[i]);
                        }
                        kfree(prz_ar);
                        prz_ar = NULL;
                        goto fail;
                }
                *paddr += zone_sz;
                prz_ar[i]->type = pstore_name_to_type(name);
        }

        *przs = prz_ar;
        return 0;

fail:
        *cnt = 0;
        return err;
}

static int ramoops_init_prz(const char *name,
                            struct device *dev, struct ramoops_context *cxt,
                            struct persistent_ram_zone **prz,
                            phys_addr_t *paddr, size_t sz, u32 sig)
{
        char *label;

        if (!sz)
                return 0;

        if (*paddr + sz - cxt->phys_addr > cxt->size) {
                dev_err(dev, "no room for %s mem region (0x%zx@0x%llx) in (0x%lx@0x%llx)\n",
                        name, sz, (unsigned long long)*paddr,
                        cxt->size, (unsigned long long)cxt->phys_addr);
                return -ENOMEM;
        }

        label = kasprintf(GFP_KERNEL, "ramoops:%s", name);
        *prz = persistent_ram_new(*paddr, sz, sig, &cxt->ecc_info,
                                  cxt->memtype, PRZ_FLAG_ZAP_OLD, label);
        kfree(label);
        if (IS_ERR(*prz)) {
                int err = PTR_ERR(*prz);

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

        *paddr += sz;
        (*prz)->type = pstore_name_to_type(name);

        return 0;
}

/* Read a u32 from a dt property and make sure it's safe for an int. */
static int ramoops_parse_dt_u32(struct platform_device *pdev,
                                const char *propname,
                                u32 default_value, u32 *value)
{
        u32 val32 = 0;
        int ret;

        ret = of_property_read_u32(pdev->dev.of_node, propname, &val32);
        if (ret == -EINVAL) {
                /* field is missing, use default value. */
                val32 = default_value;
        } else if (ret < 0) {
                dev_err(&pdev->dev, "failed to parse property %s: %d\n",
                        propname, ret);
                return ret;
        }

        /* Sanity check our results. */
        if (val32 > INT_MAX) {
                dev_err(&pdev->dev, "%s %u > INT_MAX\n", propname, val32);
                return -EOVERFLOW;
        }

        *value = val32;
        return 0;
}

static int ramoops_parse_dt(struct platform_device *pdev,
                            struct ramoops_platform_data *pdata)
{
        struct device_node *of_node = pdev->dev.of_node;
        struct device_node *parent_node;
        struct resource *res;
        u32 value;
        int ret;

        dev_dbg(&pdev->dev, "using Device Tree\n");

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res) {
                dev_err(&pdev->dev,
                        "failed to locate DT /reserved-memory resource\n");
                return -EINVAL;
        }

        pdata->mem_size = resource_size(res);
        pdata->mem_address = res->start;
        /*
         * Setting "unbuffered" is deprecated and will be ignored if
         * "mem_type" is also specified.
         */
        pdata->mem_type = of_property_read_bool(of_node, "unbuffered");
        /*
         * Setting "no-dump-oops" is deprecated and will be ignored if
         * "max_reason" is also specified.
         */
        if (of_property_read_bool(of_node, "no-dump-oops"))
                pdata->max_reason = KMSG_DUMP_PANIC;
        else
                pdata->max_reason = KMSG_DUMP_OOPS;

#define parse_u32(name, field, default_value) {                         \
                ret = ramoops_parse_dt_u32(pdev, name, default_value,   \
                                            &value);                    \
                if (ret < 0)                                            \
                        return ret;                                     \
                field = value;                                          \
        }

        parse_u32("mem-type", pdata->mem_type, pdata->mem_type);
        parse_u32("record-size", pdata->record_size, 0);
        parse_u32("console-size", pdata->console_size, 0);
        parse_u32("ftrace-size", pdata->ftrace_size, 0);
        parse_u32("pmsg-size", pdata->pmsg_size, 0);
        parse_u32("ecc-size", pdata->ecc_info.ecc_size, 0);
        parse_u32("flags", pdata->flags, 0);
        parse_u32("max-reason", pdata->max_reason, pdata->max_reason);

#undef parse_u32

        /*
         * Some old Chromebooks relied on the kernel setting the
         * console_size and pmsg_size to the record size since that's
         * what the downstream kernel did.  These same Chromebooks had
         * "ramoops" straight under the root node which isn't
         * according to the current upstream bindings (though it was
         * arguably acceptable under a prior version of the bindings).
         * Let's make those old Chromebooks work by detecting that
         * we're not a child of "reserved-memory" and mimicking the
         * expected behavior.
         */
        parent_node = of_get_parent(of_node);
        if (!of_node_name_eq(parent_node, "reserved-memory") &&
            !pdata->console_size && !pdata->ftrace_size &&
            !pdata->pmsg_size && !pdata->ecc_info.ecc_size) {
                pdata->console_size = pdata->record_size;
                pdata->pmsg_size = pdata->record_size;
        }
        of_node_put(parent_node);

        return 0;
}

static int ramoops_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct ramoops_platform_data *pdata = dev->platform_data;
        struct ramoops_platform_data pdata_local;
        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) {
                pr_err("already initialized\n");
                goto fail_out;
        }

        if (dev_of_node(dev) && !pdata) {
                pdata = &pdata_local;
                memset(pdata, 0, sizeof(*pdata));

                err = ramoops_parse_dt(pdev, pdata);
                if (err < 0)
                        goto fail_out;
        }

        /* Make sure we didn't get bogus platform data pointer. */
        if (!pdata) {
                pr_err("NULL platform data\n");
                err = -EINVAL;
                goto fail_out;
        }

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

        if (pdata->record_size && !is_power_of_2(pdata->record_size))
                pdata->record_size = rounddown_pow_of_two(pdata->record_size);
        if (pdata->console_size && !is_power_of_2(pdata->console_size))
                pdata->console_size = rounddown_pow_of_two(pdata->console_size);
        if (pdata->ftrace_size && !is_power_of_2(pdata->ftrace_size))
                pdata->ftrace_size = rounddown_pow_of_two(pdata->ftrace_size);
        if (pdata->pmsg_size && !is_power_of_2(pdata->pmsg_size))
                pdata->pmsg_size = rounddown_pow_of_two(pdata->pmsg_size);

        cxt->size = pdata->mem_size;
        cxt->phys_addr = pdata->mem_address;
        cxt->memtype = pdata->mem_type;
        cxt->record_size = pdata->record_size;
        cxt->console_size = pdata->console_size;
        cxt->ftrace_size = pdata->ftrace_size;
        cxt->pmsg_size = pdata->pmsg_size;
        cxt->flags = pdata->flags;
        cxt->ecc_info = pdata->ecc_info;

        paddr = cxt->phys_addr;

        dump_mem_sz = cxt->size - cxt->console_size - cxt->ftrace_size
                        - cxt->pmsg_size;
        err = ramoops_init_przs("dmesg", dev, cxt, &cxt->dprzs, &paddr,
                                dump_mem_sz, cxt->record_size,
                                &cxt->max_dump_cnt, 0, 0);
        if (err)
                goto fail_init;

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

        err = ramoops_init_prz("pmsg", dev, cxt, &cxt->mprz, &paddr,
                                cxt->pmsg_size, 0);
        if (err)
                goto fail_init;

        cxt->max_ftrace_cnt = (cxt->flags & RAMOOPS_FLAG_FTRACE_PER_CPU)
                                ? nr_cpu_ids
                                : 1;
        err = ramoops_init_przs("ftrace", dev, cxt, &cxt->fprzs, &paddr,
                                cxt->ftrace_size, -1,
                                &cxt->max_ftrace_cnt, LINUX_VERSION_CODE,
                                (cxt->flags & RAMOOPS_FLAG_FTRACE_PER_CPU)
                                        ? PRZ_FLAG_NO_LOCK : 0);
        if (err)
                goto fail_init;

        cxt->pstore.data = cxt;
        /*
         * Prepare frontend flags based on which areas are initialized.
         * For ramoops_init_przs() cases, the "max count" variable tells
         * if there are regions present. For ramoops_init_prz() cases,
         * the single region size is how to check.
         */
        cxt->pstore.flags = 0;
        if (cxt->max_dump_cnt) {
                cxt->pstore.flags |= PSTORE_FLAGS_DMESG;
                cxt->pstore.max_reason = pdata->max_reason;
        }
        if (cxt->console_size)
                cxt->pstore.flags |= PSTORE_FLAGS_CONSOLE;
        if (cxt->max_ftrace_cnt)
                cxt->pstore.flags |= PSTORE_FLAGS_FTRACE;
        if (cxt->pmsg_size)
                cxt->pstore.flags |= PSTORE_FLAGS_PMSG;

        /*
         * Since bufsize is only used for dmesg crash dumps, it
         * must match the size of the dprz record (after PRZ header
         * and ECC bytes have been accounted for).
         */
        if (cxt->pstore.flags & PSTORE_FLAGS_DMESG) {
                cxt->pstore.bufsize = cxt->dprzs[0]->buffer_size;
                cxt->pstore.buf = kvzalloc(cxt->pstore.bufsize, GFP_KERNEL);
                if (!cxt->pstore.buf) {
                        pr_err("cannot allocate pstore crash dump buffer\n");
                        err = -ENOMEM;
                        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;
        ramoops_max_reason = pdata->max_reason;
        ramoops_console_size = pdata->console_size;
        ramoops_pmsg_size = pdata->pmsg_size;
        ramoops_ftrace_size = pdata->ftrace_size;
        mem_type = pdata->mem_type;
        ramoops_ecc = pdata->ecc_info.ecc_size;

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

        return 0;

fail_buf:
        kvfree(cxt->pstore.buf);
fail_clear:
        cxt->pstore.bufsize = 0;
fail_init:
        ramoops_free_przs(cxt);
fail_out:
        return err;
}

static void ramoops_remove(struct platform_device *pdev)
{
        struct ramoops_context *cxt = &oops_cxt;

        pstore_unregister(&cxt->pstore);

        kvfree(cxt->pstore.buf);
        cxt->pstore.bufsize = 0;

        ramoops_free_przs(cxt);
}

static const struct of_device_id dt_match[] = {
        { .compatible = "ramoops" },
        {}
};
MODULE_DEVICE_TABLE(of, dt_match);

static struct platform_driver ramoops_driver = {
        .probe          = ramoops_probe,
        .remove         = ramoops_remove,
        .driver         = {
                .name           = "ramoops",
                .of_match_table = dt_match,
        },
};

static inline void ramoops_unregister_dummy(void)
{
        platform_device_unregister(dummy);
        dummy = NULL;
}

static void __init ramoops_register_dummy(void)
{
        struct ramoops_platform_data pdata;

        if (mem_name) {
                phys_addr_t start;
                phys_addr_t size;

                if (reserve_mem_find_by_name(mem_name, &start, &size)) {
                        mem_address = start;
                        mem_size = size;
                }
        }

        /*
         * Prepare a dummy platform data structure to carry the module
         * parameters. If mem_size isn't set, then there are no module
         * parameters, and we can skip this.
         */
        if (!mem_size)
                return;

        pr_info("using module parameters\n");

        memset(&pdata, 0, sizeof(pdata));
        pdata.mem_size = mem_size;
        pdata.mem_address = mem_address;
        pdata.mem_type = mem_type;
        pdata.record_size = record_size;
        pdata.console_size = ramoops_console_size;
        pdata.ftrace_size = ramoops_ftrace_size;
        pdata.pmsg_size = ramoops_pmsg_size;
        /* If "max_reason" is set, its value has priority over "dump_oops". */
        if (ramoops_max_reason >= 0)
                pdata.max_reason = ramoops_max_reason;
        /* Otherwise, if "dump_oops" is set, parse it into "max_reason". */
        else if (ramoops_dump_oops != -1)
                pdata.max_reason = ramoops_dump_oops ? KMSG_DUMP_OOPS
                                                     : KMSG_DUMP_PANIC;
        /* And if neither are explicitly set, use the default. */
        else
                pdata.max_reason = KMSG_DUMP_OOPS;
        pdata.flags = RAMOOPS_FLAG_FTRACE_PER_CPU;

        /*
         * For backwards compatibility ramoops.ecc=1 means 16 bytes ECC
         * (using 1 byte for ECC isn't much of use anyway).
         */
        pdata.ecc_info.ecc_size = ramoops_ecc == 1 ? 16 : ramoops_ecc;

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

static int __init ramoops_init(void)
{
        int ret;

        ramoops_register_dummy();
        ret = platform_driver_register(&ramoops_driver);
        if (ret != 0)
                ramoops_unregister_dummy();

        return ret;
}
postcore_initcall(ramoops_init);

static void __exit ramoops_exit(void)
{
        platform_driver_unregister(&ramoops_driver);
        ramoops_unregister_dummy();
}
module_exit(ramoops_exit);

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