/*
 * Hypervisor-assisted dump
 *
 * Linas Vepstas, Manish Ahuja 2008
 * Copyright 2008 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.
 *
 */

#include <linux/gfp.h>
#include <linux/init.h>
#include <linux/kobject.h>
#include <linux/mm.h>
#include <linux/of.h>
#include <linux/pfn.h>
#include <linux/swap.h>
#include <linux/sysfs.h>

#include <asm/page.h>
#include <asm/phyp_dump.h>
#include <asm/machdep.h>
#include <asm/prom.h>
#include <asm/rtas.h>

/* Variables, used to communicate data between early boot and late boot */
static struct phyp_dump phyp_dump_vars;
struct phyp_dump *phyp_dump_info = &phyp_dump_vars;

static int ibm_configure_kernel_dump;
/* ------------------------------------------------- */
/* RTAS interfaces to declare the dump regions */

struct dump_section {
        u32 dump_flags;
        u16 source_type;
        u16 error_flags;
        u64 source_address;
        u64 source_length;
        u64 length_copied;
        u64 destination_address;
};

struct phyp_dump_header {
        u32 version;
        u16 num_of_sections;
        u16 status;

        u32 first_offset_section;
        u32 dump_disk_section;
        u64 block_num_dd;
        u64 num_of_blocks_dd;
        u32 offset_dd;
        u32 maxtime_to_auto;
        /* No dump disk path string used */

        struct dump_section cpu_data;
        struct dump_section hpte_data;
        struct dump_section kernel_data;
};

/* The dump header *must be* in low memory, so .bss it */
static struct phyp_dump_header phdr;

#define NUM_DUMP_SECTIONS       3
#define DUMP_HEADER_VERSION     0x1
#define DUMP_REQUEST_FLAG       0x1
#define DUMP_SOURCE_CPU         0x0001
#define DUMP_SOURCE_HPTE        0x0002
#define DUMP_SOURCE_RMO         0x0011
#define DUMP_ERROR_FLAG         0x2000
#define DUMP_TRIGGERED          0x4000
#define DUMP_PERFORMED          0x8000


/**
 * init_dump_header() - initialize the header declaring a dump
 * Returns: length of dump save area.
 *
 * When the hypervisor saves crashed state, it needs to put
 * it somewhere. The dump header tells the hypervisor where
 * the data can be saved.
 */
static unsigned long init_dump_header(struct phyp_dump_header *ph)
{
        unsigned long addr_offset = 0;

        /* Set up the dump header */
        ph->version = DUMP_HEADER_VERSION;
        ph->num_of_sections = NUM_DUMP_SECTIONS;
        ph->status = 0;

        ph->first_offset_section =
                (u32)offsetof(struct phyp_dump_header, cpu_data);
        ph->dump_disk_section = 0;
        ph->block_num_dd = 0;
        ph->num_of_blocks_dd = 0;
        ph->offset_dd = 0;

        ph->maxtime_to_auto = 0; /* disabled */

        /* The first two sections are mandatory */
        ph->cpu_data.dump_flags = DUMP_REQUEST_FLAG;
        ph->cpu_data.source_type = DUMP_SOURCE_CPU;
        ph->cpu_data.source_address = 0;
        ph->cpu_data.source_length = phyp_dump_info->cpu_state_size;
        ph->cpu_data.destination_address = addr_offset;
        addr_offset += phyp_dump_info->cpu_state_size;

        ph->hpte_data.dump_flags = DUMP_REQUEST_FLAG;
        ph->hpte_data.source_type = DUMP_SOURCE_HPTE;
        ph->hpte_data.source_address = 0;
        ph->hpte_data.source_length = phyp_dump_info->hpte_region_size;
        ph->hpte_data.destination_address = addr_offset;
        addr_offset += phyp_dump_info->hpte_region_size;

        /* This section describes the low kernel region */
        ph->kernel_data.dump_flags = DUMP_REQUEST_FLAG;
        ph->kernel_data.source_type = DUMP_SOURCE_RMO;
        ph->kernel_data.source_address = PHYP_DUMP_RMR_START;
        ph->kernel_data.source_length = PHYP_DUMP_RMR_END;
        ph->kernel_data.destination_address = addr_offset;
        addr_offset += ph->kernel_data.source_length;

        return addr_offset;
}

static void print_dump_header(const struct phyp_dump_header *ph)
{
#ifdef DEBUG
        if (ph == NULL)
                return;

        printk(KERN_INFO "dump header:\n");
        /* setup some ph->sections required */
        printk(KERN_INFO "version = %d\n", ph->version);
        printk(KERN_INFO "Sections = %d\n", ph->num_of_sections);
        printk(KERN_INFO "Status = 0x%x\n", ph->status);

        /* No ph->disk, so all should be set to 0 */
        printk(KERN_INFO "Offset to first section 0x%x\n",
                ph->first_offset_section);
        printk(KERN_INFO "dump disk sections should be zero\n");
        printk(KERN_INFO "dump disk section = %d\n", ph->dump_disk_section);
        printk(KERN_INFO "block num = %lld\n", ph->block_num_dd);
        printk(KERN_INFO "number of blocks = %lld\n", ph->num_of_blocks_dd);
        printk(KERN_INFO "dump disk offset = %d\n", ph->offset_dd);
        printk(KERN_INFO "Max auto time= %d\n", ph->maxtime_to_auto);

        /*set cpu state and hpte states as well scratch pad area */
        printk(KERN_INFO " CPU AREA\n");
        printk(KERN_INFO "cpu dump_flags =%d\n", ph->cpu_data.dump_flags);
        printk(KERN_INFO "cpu source_type =%d\n", ph->cpu_data.source_type);
        printk(KERN_INFO "cpu error_flags =%d\n", ph->cpu_data.error_flags);
        printk(KERN_INFO "cpu source_address =%llx\n",
                ph->cpu_data.source_address);
        printk(KERN_INFO "cpu source_length =%llx\n",
                ph->cpu_data.source_length);
        printk(KERN_INFO "cpu length_copied =%llx\n",
                ph->cpu_data.length_copied);

        printk(KERN_INFO " HPTE AREA\n");
        printk(KERN_INFO "HPTE dump_flags =%d\n", ph->hpte_data.dump_flags);
        printk(KERN_INFO "HPTE source_type =%d\n", ph->hpte_data.source_type);
        printk(KERN_INFO "HPTE error_flags =%d\n", ph->hpte_data.error_flags);
        printk(KERN_INFO "HPTE source_address =%llx\n",
                ph->hpte_data.source_address);
        printk(KERN_INFO "HPTE source_length =%llx\n",
                ph->hpte_data.source_length);
        printk(KERN_INFO "HPTE length_copied =%llx\n",
                ph->hpte_data.length_copied);

        printk(KERN_INFO " SRSD AREA\n");
        printk(KERN_INFO "SRSD dump_flags =%d\n", ph->kernel_data.dump_flags);
        printk(KERN_INFO "SRSD source_type =%d\n", ph->kernel_data.source_type);
        printk(KERN_INFO "SRSD error_flags =%d\n", ph->kernel_data.error_flags);
        printk(KERN_INFO "SRSD source_address =%llx\n",
                ph->kernel_data.source_address);
        printk(KERN_INFO "SRSD source_length =%llx\n",
                ph->kernel_data.source_length);
        printk(KERN_INFO "SRSD length_copied =%llx\n",
                ph->kernel_data.length_copied);
#endif
}

static ssize_t show_phyp_dump_active(struct kobject *kobj,
                        struct kobj_attribute *attr, char *buf)
{

        /* create filesystem entry so kdump is phyp-dump aware */
        return sprintf(buf, "%lx\n", phyp_dump_info->phyp_dump_at_boot);
}

static struct kobj_attribute pdl = __ATTR(phyp_dump_active, 0600,
                                        show_phyp_dump_active,
                                        NULL);

static void register_dump_area(struct phyp_dump_header *ph, unsigned long addr)
{
        int rc;

        /* Add addr value if not initialized before */
        if (ph->cpu_data.destination_address == 0) {
                ph->cpu_data.destination_address += addr;
                ph->hpte_data.destination_address += addr;
                ph->kernel_data.destination_address += addr;
        }

        /* ToDo Invalidate kdump and free memory range. */

        do {
                rc = rtas_call(ibm_configure_kernel_dump, 3, 1, NULL,
                                1, ph, sizeof(struct phyp_dump_header));
        } while (rtas_busy_delay(rc));

        if (rc) {
                printk(KERN_ERR "phyp-dump: unexpected error (%d) on "
                                                "register\n", rc);
                print_dump_header(ph);
                return;
        }

        rc = sysfs_create_file(kernel_kobj, &pdl.attr);
        if (rc)
                printk(KERN_ERR "phyp-dump: unable to create sysfs"
                                " file (%d)\n", rc);
}

static
void invalidate_last_dump(struct phyp_dump_header *ph, unsigned long addr)
{
        int rc;

        /* Add addr value if not initialized before */
        if (ph->cpu_data.destination_address == 0) {
                ph->cpu_data.destination_address += addr;
                ph->hpte_data.destination_address += addr;
                ph->kernel_data.destination_address += addr;
        }

        do {
                rc = rtas_call(ibm_configure_kernel_dump, 3, 1, NULL,
                                2, ph, sizeof(struct phyp_dump_header));
        } while (rtas_busy_delay(rc));

        if (rc) {
                printk(KERN_ERR "phyp-dump: unexpected error (%d) "
                                                "on invalidate\n", rc);
                print_dump_header(ph);
        }
}

/* ------------------------------------------------- */
/**
 * release_memory_range -- release memory previously memblock_reserved
 * @start_pfn: starting physical frame number
 * @nr_pages: number of pages to free.
 *
 * This routine will release memory that had been previously
 * memblock_reserved in early boot. The released memory becomes
 * available for genreal use.
 */
static void release_memory_range(unsigned long start_pfn,
                        unsigned long nr_pages)
{
        struct page *rpage;
        unsigned long end_pfn;
        long i;

        end_pfn = start_pfn + nr_pages;

        for (i = start_pfn; i <= end_pfn; i++) {
                rpage = pfn_to_page(i);
                if (PageReserved(rpage)) {
                        ClearPageReserved(rpage);
                        init_page_count(rpage);
                        __free_page(rpage);
                        totalram_pages++;
                }
        }
}

/**
 * track_freed_range -- Counts the range being freed.
 * Once the counter goes to zero, it re-registers dump for
 * future use.
 */
static void
track_freed_range(unsigned long addr, unsigned long length)
{
        static unsigned long scratch_area_size, reserved_area_size;

        if (addr < phyp_dump_info->init_reserve_start)
                return;

        if ((addr >= phyp_dump_info->init_reserve_start) &&
            (addr <= phyp_dump_info->init_reserve_start +
             phyp_dump_info->init_reserve_size))
                reserved_area_size += length;

        if ((addr >= phyp_dump_info->reserved_scratch_addr) &&
            (addr <= phyp_dump_info->reserved_scratch_addr +
             phyp_dump_info->reserved_scratch_size))
                scratch_area_size += length;

        if ((reserved_area_size == phyp_dump_info->init_reserve_size) &&
            (scratch_area_size == phyp_dump_info->reserved_scratch_size)) {

                invalidate_last_dump(&phdr,
                                phyp_dump_info->reserved_scratch_addr);
                register_dump_area(&phdr,
                                phyp_dump_info->reserved_scratch_addr);
        }
}

/* ------------------------------------------------- */
/**
 * sysfs_release_region -- sysfs interface to release memory range.
 *
 * Usage:
 *   "echo <start addr> <length> > /sys/kernel/release_region"
 *
 * Example:
 *   "echo 0x40000000 0x10000000 > /sys/kernel/release_region"
 *
 * will release 256MB starting at 1GB.
 */
static ssize_t store_release_region(struct kobject *kobj,
                                struct kobj_attribute *attr,
                                const char *buf, size_t count)
{
        unsigned long start_addr, length, end_addr;
        unsigned long start_pfn, nr_pages;
        ssize_t ret;

        ret = sscanf(buf, "%lx %lx", &start_addr, &length);
        if (ret != 2)
                return -EINVAL;

        track_freed_range(start_addr, length);

        /* Range-check - don't free any reserved memory that
         * wasn't reserved for phyp-dump */
        if (start_addr < phyp_dump_info->init_reserve_start)
                start_addr = phyp_dump_info->init_reserve_start;

        end_addr = phyp_dump_info->init_reserve_start +
                        phyp_dump_info->init_reserve_size;
        if (start_addr+length > end_addr)
                length = end_addr - start_addr;

        /* Release the region of memory assed in by user */
        start_pfn = PFN_DOWN(start_addr);
        nr_pages = PFN_DOWN(length);
        release_memory_range(start_pfn, nr_pages);

        return count;
}

static ssize_t show_release_region(struct kobject *kobj,
                        struct kobj_attribute *attr, char *buf)
{
        u64 second_addr_range;

        /* total reserved size - start of scratch area */
        second_addr_range = phyp_dump_info->init_reserve_size -
                                phyp_dump_info->reserved_scratch_size;
        return sprintf(buf, "CPU:0x%llx-0x%llx: HPTE:0x%llx-0x%llx:"
                            " DUMP:0x%llx-0x%llx, 0x%lx-0x%llx:\n",
                phdr.cpu_data.destination_address,
                phdr.cpu_data.length_copied,
                phdr.hpte_data.destination_address,
                phdr.hpte_data.length_copied,
                phdr.kernel_data.destination_address,
                phdr.kernel_data.length_copied,
                phyp_dump_info->init_reserve_start,
                second_addr_range);
}

static struct kobj_attribute rr = __ATTR(release_region, 0600,
                                        show_release_region,
                                        store_release_region);

static int __init phyp_dump_setup(void)
{
        struct device_node *rtas;
        const struct phyp_dump_header *dump_header = NULL;
        unsigned long dump_area_start;
        unsigned long dump_area_length;
        int header_len = 0;
        int rc;

        /* If no memory was reserved in early boot, there is nothing to do */
        if (phyp_dump_info->init_reserve_size == 0)
                return 0;

        /* Return if phyp dump not supported */
        if (!phyp_dump_info->phyp_dump_configured)
                return -ENOSYS;

        /* Is there dump data waiting for us? If there isn't,
         * then register a new dump area, and release all of
         * the rest of the reserved ram.
         *
         * The /rtas/ibm,kernel-dump rtas node is present only
         * if there is dump data waiting for us.
         */
        rtas = of_find_node_by_path("/rtas");
        if (rtas) {
                dump_header = of_get_property(rtas, "ibm,kernel-dump",
                                                &header_len);
                of_node_put(rtas);
        }

        ibm_configure_kernel_dump = rtas_token("ibm,configure-kernel-dump");

        print_dump_header(dump_header);
        dump_area_length = init_dump_header(&phdr);
        /* align down */
        dump_area_start = phyp_dump_info->init_reserve_start & PAGE_MASK;

        if (dump_header == NULL) {
                register_dump_area(&phdr, dump_area_start);
                return 0;
        }

        /* re-register the dump area, if old dump was invalid */
        if ((dump_header) && (dump_header->status & DUMP_ERROR_FLAG)) {
                invalidate_last_dump(&phdr, dump_area_start);
                register_dump_area(&phdr, dump_area_start);
                return 0;
        }

        if (dump_header) {
                phyp_dump_info->reserved_scratch_addr =
                                dump_header->cpu_data.destination_address;
                phyp_dump_info->reserved_scratch_size =
                                dump_header->cpu_data.source_length +
                                dump_header->hpte_data.source_length +
                                dump_header->kernel_data.source_length;
        }

        /* Should we create a dump_subsys, analogous to s390/ipl.c ? */
        rc = sysfs_create_file(kernel_kobj, &rr.attr);
        if (rc)
                printk(KERN_ERR "phyp-dump: unable to create sysfs file (%d)\n",
                                                                        rc);

        /* ToDo: re-register the dump area, for next time. */
        return 0;
}
machine_subsys_initcall(pseries, phyp_dump_setup);

int __init early_init_dt_scan_phyp_dump(unsigned long node,
                const char *uname, int depth, void *data)
{
        const unsigned int *sizes;

        phyp_dump_info->phyp_dump_configured = 0;
        phyp_dump_info->phyp_dump_is_active = 0;

        if (depth != 1 || strcmp(uname, "rtas") != 0)
                return 0;

        if (of_get_flat_dt_prop(node, "ibm,configure-kernel-dump", NULL))
                phyp_dump_info->phyp_dump_configured++;

        if (of_get_flat_dt_prop(node, "ibm,dump-kernel", NULL))
                phyp_dump_info->phyp_dump_is_active++;

        sizes = of_get_flat_dt_prop(node, "ibm,configure-kernel-dump-sizes",
                                    NULL);
        if (!sizes)
                return 0;

        if (sizes[0] == 1)
                phyp_dump_info->cpu_state_size = *((unsigned long *)&sizes[1]);

        if (sizes[3] == 2)
                phyp_dump_info->hpte_region_size =
                                                *((unsigned long *)&sizes[4]);
        return 1;
}

/* Look for phyp_dump= cmdline option */
static int __init early_phyp_dump_enabled(char *p)
{
        phyp_dump_info->phyp_dump_at_boot = 1;

        if (!p)
                return 0;

        if (strncmp(p, "1", 1) == 0)
                phyp_dump_info->phyp_dump_at_boot = 1;
        else if (strncmp(p, "0", 1) == 0)
                phyp_dump_info->phyp_dump_at_boot = 0;

        return 0;
}
early_param("phyp_dump", early_phyp_dump_enabled);

/* Look for phyp_dump_reserve_size= cmdline option */
static int __init early_phyp_dump_reserve_size(char *p)
{
        if (p)
                phyp_dump_info->reserve_bootvar = memparse(p, &p);

        return 0;
}
early_param("phyp_dump_reserve_size", early_phyp_dump_reserve_size);