/*
 * PowerNV OPAL Firmware Update Interface
 *
 * Copyright 2013 IBM Corp.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#define DEBUG

#include <linux/kernel.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/kobject.h>
#include <linux/sysfs.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/pagemap.h>
#include <linux/delay.h>

#include <asm/opal.h>

/* FLASH status codes */
#define FLASH_NO_OP             -1099   /* No operation initiated by user */
#define FLASH_NO_AUTH           -9002   /* Not a service authority partition */

/* Validate image status values */
#define VALIDATE_IMG_READY      -1001   /* Image ready for validation */
#define VALIDATE_IMG_INCOMPLETE -1002   /* User copied < VALIDATE_BUF_SIZE */

/* Manage image status values */
#define MANAGE_ACTIVE_ERR       -9001   /* Cannot overwrite active img */

/* Flash image status values */
#define FLASH_IMG_READY         0       /* Img ready for flash on reboot */
#define FLASH_INVALID_IMG       -1003   /* Flash image shorter than expected */
#define FLASH_IMG_NULL_DATA     -1004   /* Bad data in sg list entry */
#define FLASH_IMG_BAD_LEN       -1005   /* Bad length in sg list entry */

/* Manage operation tokens */
#define FLASH_REJECT_TMP_SIDE   0       /* Reject temporary fw image */
#define FLASH_COMMIT_TMP_SIDE   1       /* Commit temporary fw image */

/* Update tokens */
#define FLASH_UPDATE_CANCEL     0       /* Cancel update request */
#define FLASH_UPDATE_INIT       1       /* Initiate update */

/* Validate image update result tokens */
#define VALIDATE_TMP_UPDATE     0     /* T side will be updated */
#define VALIDATE_FLASH_AUTH     1     /* Partition does not have authority */
#define VALIDATE_INVALID_IMG    2     /* Candidate image is not valid */
#define VALIDATE_CUR_UNKNOWN    3     /* Current fixpack level is unknown */
/*
 * Current T side will be committed to P side before being replace with new
 * image, and the new image is downlevel from current image
 */
#define VALIDATE_TMP_COMMIT_DL  4
/*
 * Current T side will be committed to P side before being replaced with new
 * image
 */
#define VALIDATE_TMP_COMMIT     5
/*
 * T side will be updated with a downlevel image
 */
#define VALIDATE_TMP_UPDATE_DL  6
/*
 * The candidate image's release date is later than the system's firmware
 * service entitlement date - service warranty period has expired
 */
#define VALIDATE_OUT_OF_WRNTY   7

/* Validate buffer size */
#define VALIDATE_BUF_SIZE       4096

/* XXX: Assume candidate image size is <= 1GB */
#define MAX_IMAGE_SIZE  0x40000000

/* Image status */
enum {
        IMAGE_INVALID,
        IMAGE_LOADING,
        IMAGE_READY,
};

/* Candidate image data */
struct image_data_t {
        int             status;
        void            *data;
        uint32_t        size;
};

/* Candidate image header */
struct image_header_t {
        uint16_t        magic;
        uint16_t        version;
        uint32_t        size;
};

struct validate_flash_t {
        int             status;         /* Return status */
        void            *buf;           /* Candidate image buffer */
        uint32_t        buf_size;       /* Image size */
        uint32_t        result;         /* Update results token */
};

struct manage_flash_t {
        int status;             /* Return status */
};

struct update_flash_t {
        int status;             /* Return status */
};

static struct image_header_t    image_header;
static struct image_data_t      image_data;
static struct validate_flash_t  validate_flash_data;
static struct manage_flash_t    manage_flash_data;

/* Initialize update_flash_data status to No Operation */
static struct update_flash_t    update_flash_data = {
        .status = FLASH_NO_OP,
};

static DEFINE_MUTEX(image_data_mutex);

/*
 * Validate candidate image
 */
static inline void opal_flash_validate(void)
{
        long ret;
        void *buf = validate_flash_data.buf;
        __be32 size = cpu_to_be32(validate_flash_data.buf_size);
        __be32 result;

        ret = opal_validate_flash(__pa(buf), &size, &result);

        validate_flash_data.status = ret;
        validate_flash_data.buf_size = be32_to_cpu(size);
        validate_flash_data.result = be32_to_cpu(result);
}

/*
 * Validate output format:
 *     validate result token
 *     current image version details
 *     new image version details
 */
static ssize_t validate_show(struct kobject *kobj,
                             struct kobj_attribute *attr, char *buf)
{
        struct validate_flash_t *args_buf = &validate_flash_data;
        int len;

        /* Candidate image is not validated */
        if (args_buf->status < VALIDATE_TMP_UPDATE) {
                len = sprintf(buf, "%d\n", args_buf->status);
                goto out;
        }

        /* Result token */
        len = sprintf(buf, "%d\n", args_buf->result);

        /* Current and candidate image version details */
        if ((args_buf->result != VALIDATE_TMP_UPDATE) &&
            (args_buf->result < VALIDATE_CUR_UNKNOWN))
                goto out;

        if (args_buf->buf_size > (VALIDATE_BUF_SIZE - len)) {
                memcpy(buf + len, args_buf->buf, VALIDATE_BUF_SIZE - len);
                len = VALIDATE_BUF_SIZE;
        } else {
                memcpy(buf + len, args_buf->buf, args_buf->buf_size);
                len += args_buf->buf_size;
        }
out:
        /* Set status to default */
        args_buf->status = FLASH_NO_OP;
        return len;
}

/*
 * Validate candidate firmware image
 *
 * Note:
 *   We are only interested in first 4K bytes of the
 *   candidate image.
 */
static ssize_t validate_store(struct kobject *kobj,
                              struct kobj_attribute *attr,
                              const char *buf, size_t count)
{
        struct validate_flash_t *args_buf = &validate_flash_data;

        if (buf[0] != '1')
                return -EINVAL;

        mutex_lock(&image_data_mutex);

        if (image_data.status != IMAGE_READY ||
            image_data.size < VALIDATE_BUF_SIZE) {
                args_buf->result = VALIDATE_INVALID_IMG;
                args_buf->status = VALIDATE_IMG_INCOMPLETE;
                goto out;
        }

        /* Copy first 4k bytes of candidate image */
        memcpy(args_buf->buf, image_data.data, VALIDATE_BUF_SIZE);

        args_buf->status = VALIDATE_IMG_READY;
        args_buf->buf_size = VALIDATE_BUF_SIZE;

        /* Validate candidate image */
        opal_flash_validate();

out:
        mutex_unlock(&image_data_mutex);
        return count;
}

/*
 * Manage flash routine
 */
static inline void opal_flash_manage(uint8_t op)
{
        struct manage_flash_t *const args_buf = &manage_flash_data;

        args_buf->status = opal_manage_flash(op);
}

/*
 * Show manage flash status
 */
static ssize_t manage_show(struct kobject *kobj,
                           struct kobj_attribute *attr, char *buf)
{
        struct manage_flash_t *const args_buf = &manage_flash_data;
        int rc;

        rc = sprintf(buf, "%d\n", args_buf->status);
        /* Set status to default*/
        args_buf->status = FLASH_NO_OP;
        return rc;
}

/*
 * Manage operations:
 *   0 - Reject
 *   1 - Commit
 */
static ssize_t manage_store(struct kobject *kobj,
                            struct kobj_attribute *attr,
                            const char *buf, size_t count)
{
        uint8_t op;
        switch (buf[0]) {
        case '0':
                op = FLASH_REJECT_TMP_SIDE;
                break;
        case '1':
                op = FLASH_COMMIT_TMP_SIDE;
                break;
        default:
                return -EINVAL;
        }

        /* commit/reject temporary image */
        opal_flash_manage(op);
        return count;
}

/*
 * OPAL update flash
 */
static int opal_flash_update(int op)
{
        struct opal_sg_list *list;
        unsigned long addr;
        int64_t rc = OPAL_PARAMETER;

        if (op == FLASH_UPDATE_CANCEL) {
                pr_alert("FLASH: Image update cancelled\n");
                addr = '\0';
                goto flash;
        }

        list = opal_vmalloc_to_sg_list(image_data.data, image_data.size);
        if (!list)
                goto invalid_img;

        /* First entry address */
        addr = __pa(list);

flash:
        rc = opal_update_flash(addr);

invalid_img:
        return rc;
}

/* Return CPUs to OPAL before starting FW update */
static void flash_return_cpu(void *info)
{
        int cpu = smp_processor_id();

        if (!cpu_online(cpu))
                return;

        /* Disable IRQ */
        hard_irq_disable();

        /* Return the CPU to OPAL */
        opal_return_cpu();
}

/* This gets called just before system reboots */
void opal_flash_term_callback(void)
{
        struct cpumask mask;

        if (update_flash_data.status != FLASH_IMG_READY)
                return;

        pr_alert("FLASH: Flashing new firmware\n");
        pr_alert("FLASH: Image is %u bytes\n", image_data.size);
        pr_alert("FLASH: Performing flash and reboot/shutdown\n");
        pr_alert("FLASH: This will take several minutes. Do not power off!\n");

        /* Small delay to help getting the above message out */
        msleep(500);

        /* Return secondary CPUs to firmware */
        cpumask_copy(&mask, cpu_online_mask);
        cpumask_clear_cpu(smp_processor_id(), &mask);
        if (!cpumask_empty(&mask))
                smp_call_function_many(&mask,
                                       flash_return_cpu, NULL, false);
        /* Hard disable interrupts */
        hard_irq_disable();
}

/*
 * Show candidate image status
 */
static ssize_t update_show(struct kobject *kobj,
                           struct kobj_attribute *attr, char *buf)
{
        struct update_flash_t *const args_buf = &update_flash_data;
        return sprintf(buf, "%d\n", args_buf->status);
}

/*
 * Set update image flag
 *  1 - Flash new image
 *  0 - Cancel flash request
 */
static ssize_t update_store(struct kobject *kobj,
                            struct kobj_attribute *attr,
                            const char *buf, size_t count)
{
        struct update_flash_t *const args_buf = &update_flash_data;
        int rc = count;

        mutex_lock(&image_data_mutex);

        switch (buf[0]) {
        case '0':
                if (args_buf->status == FLASH_IMG_READY)
                        opal_flash_update(FLASH_UPDATE_CANCEL);
                args_buf->status = FLASH_NO_OP;
                break;
        case '1':
                /* Image is loaded? */
                if (image_data.status == IMAGE_READY)
                        args_buf->status =
                                opal_flash_update(FLASH_UPDATE_INIT);
                else
                        args_buf->status = FLASH_INVALID_IMG;
                break;
        default:
                rc = -EINVAL;
        }

        mutex_unlock(&image_data_mutex);
        return rc;
}

/*
 * Free image buffer
 */
static void free_image_buf(void)
{
        void *addr;
        int size;

        addr = image_data.data;
        size = PAGE_ALIGN(image_data.size);
        while (size > 0) {
                ClearPageReserved(vmalloc_to_page(addr));
                addr += PAGE_SIZE;
                size -= PAGE_SIZE;
        }
        vfree(image_data.data);
        image_data.data = NULL;
        image_data.status = IMAGE_INVALID;
}

/*
 * Allocate image buffer.
 */
static int alloc_image_buf(char *buffer, size_t count)
{
        void *addr;
        int size;

        if (count < sizeof(struct image_header_t)) {
                pr_warn("FLASH: Invalid candidate image\n");
                return -EINVAL;
        }

        memcpy(&image_header, (void *)buffer, sizeof(struct image_header_t));
        image_data.size = be32_to_cpu(image_header.size);
        pr_debug("FLASH: Candidate image size = %u\n", image_data.size);

        if (image_data.size > MAX_IMAGE_SIZE) {
                pr_warn("FLASH: Too large image\n");
                return -EINVAL;
        }
        if (image_data.size < VALIDATE_BUF_SIZE) {
                pr_warn("FLASH: Image is shorter than expected\n");
                return -EINVAL;
        }

        image_data.data = vzalloc(PAGE_ALIGN(image_data.size));
        if (!image_data.data) {
                pr_err("%s : Failed to allocate memory\n", __func__);
                return -ENOMEM;
        }

        /* Pin memory */
        addr = image_data.data;
        size = PAGE_ALIGN(image_data.size);
        while (size > 0) {
                SetPageReserved(vmalloc_to_page(addr));
                addr += PAGE_SIZE;
                size -= PAGE_SIZE;
        }

        image_data.status = IMAGE_LOADING;
        return 0;
}

/*
 * Copy candidate image
 *
 * Parse candidate image header to get total image size
 * and pre-allocate required memory.
 */
static ssize_t image_data_write(struct file *filp, struct kobject *kobj,
                                struct bin_attribute *bin_attr,
                                char *buffer, loff_t pos, size_t count)
{
        int rc;

        mutex_lock(&image_data_mutex);

        /* New image ? */
        if (pos == 0) {
                /* Free memory, if already allocated */
                if (image_data.data)
                        free_image_buf();

                /* Cancel outstanding image update request */
                if (update_flash_data.status == FLASH_IMG_READY)
                        opal_flash_update(FLASH_UPDATE_CANCEL);

                /* Allocate memory */
                rc = alloc_image_buf(buffer, count);
                if (rc)
                        goto out;
        }

        if (image_data.status != IMAGE_LOADING) {
                rc = -ENOMEM;
                goto out;
        }

        if ((pos + count) > image_data.size) {
                rc = -EINVAL;
                goto out;
        }

        memcpy(image_data.data + pos, (void *)buffer, count);
        rc = count;

        /* Set image status */
        if ((pos + count) == image_data.size) {
                pr_debug("FLASH: Candidate image loaded....\n");
                image_data.status = IMAGE_READY;
        }

out:
        mutex_unlock(&image_data_mutex);
        return rc;
}

/*
 * sysfs interface :
 *  OPAL uses below sysfs files for code update.
 *  We create these files under /sys/firmware/opal.
 *
 *   image              : Interface to load candidate firmware image
 *   validate_flash     : Validate firmware image
 *   manage_flash       : Commit/Reject firmware image
 *   update_flash       : Flash new firmware image
 *
 */
static const struct bin_attribute image_data_attr = {
        .attr = {.name = "image", .mode = 0200},
        .size = MAX_IMAGE_SIZE, /* Limit image size */
        .write = image_data_write,
};

static struct kobj_attribute validate_attribute =
        __ATTR(validate_flash, 0600, validate_show, validate_store);

static struct kobj_attribute manage_attribute =
        __ATTR(manage_flash, 0600, manage_show, manage_store);

static struct kobj_attribute update_attribute =
        __ATTR(update_flash, 0600, update_show, update_store);

static struct attribute *image_op_attrs[] = {
        &validate_attribute.attr,
        &manage_attribute.attr,
        &update_attribute.attr,
        NULL    /* need to NULL terminate the list of attributes */
};

static struct attribute_group image_op_attr_group = {
        .attrs = image_op_attrs,
};

void __init opal_flash_update_init(void)
{
        int ret;

        /* Allocate validate image buffer */
        validate_flash_data.buf = kzalloc(VALIDATE_BUF_SIZE, GFP_KERNEL);
        if (!validate_flash_data.buf) {
                pr_err("%s : Failed to allocate memory\n", __func__);
                return;
        }

        /* Make sure /sys/firmware/opal directory is created */
        if (!opal_kobj) {
                pr_warn("FLASH: opal kobject is not available\n");
                goto nokobj;
        }

        /* Create the sysfs files */
        ret = sysfs_create_group(opal_kobj, &image_op_attr_group);
        if (ret) {
                pr_warn("FLASH: Failed to create sysfs files\n");
                goto nokobj;
        }

        ret = sysfs_create_bin_file(opal_kobj, &image_data_attr);
        if (ret) {
                pr_warn("FLASH: Failed to create sysfs files\n");
                goto nosysfs_file;
        }

        /* Set default status */
        validate_flash_data.status = FLASH_NO_OP;
        manage_flash_data.status = FLASH_NO_OP;
        update_flash_data.status = FLASH_NO_OP;
        image_data.status = IMAGE_INVALID;
        return;

nosysfs_file:
        sysfs_remove_group(opal_kobj, &image_op_attr_group);

nokobj:
        kfree(validate_flash_data.buf);
        return;
}