// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Dynamic reconfiguration memory support
 *
 * Copyright 2017 IBM Corporation
 */

#define pr_fmt(fmt) "drmem: " fmt

#include <linux/kernel.h>
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/memblock.h>
#include <linux/slab.h>
#include <asm/drmem.h>

static int n_root_addr_cells, n_root_size_cells;

static struct drmem_lmb_info __drmem_info;
struct drmem_lmb_info *drmem_info = &__drmem_info;
static bool in_drmem_update;

u64 drmem_lmb_memory_max(void)
{
        struct drmem_lmb *last_lmb;

        last_lmb = &drmem_info->lmbs[drmem_info->n_lmbs - 1];
        return last_lmb->base_addr + drmem_lmb_size();
}

static u32 drmem_lmb_flags(struct drmem_lmb *lmb)
{
        /*
         * Return the value of the lmb flags field minus the reserved
         * bit used internally for hotplug processing.
         */
        return lmb->flags & ~DRMEM_LMB_RESERVED;
}

static struct property *clone_property(struct property *prop, u32 prop_sz)
{
        struct property *new_prop;

        new_prop = kzalloc_obj(*new_prop);
        if (!new_prop)
                return NULL;

        new_prop->name = kstrdup(prop->name, GFP_KERNEL);
        new_prop->value = kzalloc(prop_sz, GFP_KERNEL);
        if (!new_prop->name || !new_prop->value) {
                kfree(new_prop->name);
                kfree(new_prop->value);
                kfree(new_prop);
                return NULL;
        }

        new_prop->length = prop_sz;
#if defined(CONFIG_OF_DYNAMIC)
        of_property_set_flag(new_prop, OF_DYNAMIC);
#endif
        return new_prop;
}

static int drmem_update_dt_v1(struct device_node *memory,
                              struct property *prop)
{
        struct property *new_prop;
        struct of_drconf_cell_v1 *dr_cell;
        struct drmem_lmb *lmb;
        __be32 *p;

        new_prop = clone_property(prop, prop->length);
        if (!new_prop)
                return -1;

        p = new_prop->value;
        *p++ = cpu_to_be32(drmem_info->n_lmbs);

        dr_cell = (struct of_drconf_cell_v1 *)p;

        for_each_drmem_lmb(lmb) {
                dr_cell->base_addr = cpu_to_be64(lmb->base_addr);
                dr_cell->drc_index = cpu_to_be32(lmb->drc_index);
                dr_cell->aa_index = cpu_to_be32(lmb->aa_index);
                dr_cell->flags = cpu_to_be32(drmem_lmb_flags(lmb));

                dr_cell++;
        }

        of_update_property(memory, new_prop);
        return 0;
}

static void init_drconf_v2_cell(struct of_drconf_cell_v2 *dr_cell,
                                struct drmem_lmb *lmb)
{
        dr_cell->base_addr = cpu_to_be64(lmb->base_addr);
        dr_cell->drc_index = cpu_to_be32(lmb->drc_index);
        dr_cell->aa_index = cpu_to_be32(lmb->aa_index);
        dr_cell->flags = cpu_to_be32(drmem_lmb_flags(lmb));
}

static int drmem_update_dt_v2(struct device_node *memory,
                              struct property *prop)
{
        struct property *new_prop;
        struct of_drconf_cell_v2 *dr_cell;
        struct drmem_lmb *lmb, *prev_lmb;
        u32 lmb_sets, prop_sz, seq_lmbs;
        u32 *p;

        /* First pass, determine how many LMB sets are needed. */
        lmb_sets = 0;
        prev_lmb = NULL;
        for_each_drmem_lmb(lmb) {
                if (!prev_lmb) {
                        prev_lmb = lmb;
                        lmb_sets++;
                        continue;
                }

                if (prev_lmb->aa_index != lmb->aa_index ||
                    drmem_lmb_flags(prev_lmb) != drmem_lmb_flags(lmb))
                        lmb_sets++;

                prev_lmb = lmb;
        }

        prop_sz = lmb_sets * sizeof(*dr_cell) + sizeof(__be32);
        new_prop = clone_property(prop, prop_sz);
        if (!new_prop)
                return -1;

        p = new_prop->value;
        *p++ = cpu_to_be32(lmb_sets);

        dr_cell = (struct of_drconf_cell_v2 *)p;

        /* Second pass, populate the LMB set data */
        prev_lmb = NULL;
        seq_lmbs = 0;
        for_each_drmem_lmb(lmb) {
                if (prev_lmb == NULL) {
                        /* Start of first LMB set */
                        prev_lmb = lmb;
                        init_drconf_v2_cell(dr_cell, lmb);
                        seq_lmbs++;
                        continue;
                }

                if (prev_lmb->aa_index != lmb->aa_index ||
                    drmem_lmb_flags(prev_lmb) != drmem_lmb_flags(lmb)) {
                        /* end of one set, start of another */
                        dr_cell->seq_lmbs = cpu_to_be32(seq_lmbs);
                        dr_cell++;

                        init_drconf_v2_cell(dr_cell, lmb);
                        seq_lmbs = 1;
                } else {
                        seq_lmbs++;
                }

                prev_lmb = lmb;
        }

        /* close out last LMB set */
        dr_cell->seq_lmbs = cpu_to_be32(seq_lmbs);
        of_update_property(memory, new_prop);
        return 0;
}

int drmem_update_dt(void)
{
        struct device_node *memory;
        struct property *prop;
        int rc = -1;

        memory = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
        if (!memory)
                return -1;

        /*
         * Set in_drmem_update to prevent the notifier callback to process the
         * DT property back since the change is coming from the LMB tree.
         */
        in_drmem_update = true;
        prop = of_find_property(memory, "ibm,dynamic-memory", NULL);
        if (prop) {
                rc = drmem_update_dt_v1(memory, prop);
        } else {
                prop = of_find_property(memory, "ibm,dynamic-memory-v2", NULL);
                if (prop)
                        rc = drmem_update_dt_v2(memory, prop);
        }
        in_drmem_update = false;

        of_node_put(memory);
        return rc;
}

static void read_drconf_v1_cell(struct drmem_lmb *lmb,
                                       const __be32 **prop)
{
        const __be32 *p = *prop;

        lmb->base_addr = of_read_number(p, n_root_addr_cells);
        p += n_root_addr_cells;
        lmb->drc_index = of_read_number(p++, 1);

        p++; /* skip reserved field */

        lmb->aa_index = of_read_number(p++, 1);
        lmb->flags = of_read_number(p++, 1);

        *prop = p;
}

static int
__walk_drmem_v1_lmbs(const __be32 *prop, const __be32 *usm, void *data,
                     int (*func)(struct drmem_lmb *, const __be32 **, void *))
{
        struct drmem_lmb lmb;
        u32 i, n_lmbs;
        int ret = 0;

        n_lmbs = of_read_number(prop++, 1);
        for (i = 0; i < n_lmbs; i++) {
                read_drconf_v1_cell(&lmb, &prop);
                ret = func(&lmb, &usm, data);
                if (ret)
                        break;
        }

        return ret;
}

static void read_drconf_v2_cell(struct of_drconf_cell_v2 *dr_cell,
                                       const __be32 **prop)
{
        const __be32 *p = *prop;

        dr_cell->seq_lmbs = of_read_number(p++, 1);
        dr_cell->base_addr = of_read_number(p, n_root_addr_cells);
        p += n_root_addr_cells;
        dr_cell->drc_index = of_read_number(p++, 1);
        dr_cell->aa_index = of_read_number(p++, 1);
        dr_cell->flags = of_read_number(p++, 1);

        *prop = p;
}

static int
__walk_drmem_v2_lmbs(const __be32 *prop, const __be32 *usm, void *data,
                     int (*func)(struct drmem_lmb *, const __be32 **, void *))
{
        struct of_drconf_cell_v2 dr_cell;
        struct drmem_lmb lmb;
        u32 i, j, lmb_sets;
        int ret = 0;

        lmb_sets = of_read_number(prop++, 1);
        for (i = 0; i < lmb_sets; i++) {
                read_drconf_v2_cell(&dr_cell, &prop);

                for (j = 0; j < dr_cell.seq_lmbs; j++) {
                        lmb.base_addr = dr_cell.base_addr;
                        dr_cell.base_addr += drmem_lmb_size();

                        lmb.drc_index = dr_cell.drc_index;
                        dr_cell.drc_index++;

                        lmb.aa_index = dr_cell.aa_index;
                        lmb.flags = dr_cell.flags;

                        ret = func(&lmb, &usm, data);
                        if (ret)
                                break;
                }
        }

        return ret;
}

#ifdef CONFIG_PPC_PSERIES
int __init walk_drmem_lmbs_early(unsigned long node, void *data,
                int (*func)(struct drmem_lmb *, const __be32 **, void *))
{
        const __be32 *prop, *usm;
        int len, ret = -ENODEV;

        prop = of_get_flat_dt_prop(node, "ibm,lmb-size", &len);
        if (!prop || len < dt_root_size_cells * sizeof(__be32))
                return ret;

        /* Get the address & size cells */
        n_root_addr_cells = dt_root_addr_cells;
        n_root_size_cells = dt_root_size_cells;

        drmem_info->lmb_size = dt_mem_next_cell(dt_root_size_cells, &prop);

        usm = of_get_flat_dt_prop(node, "linux,drconf-usable-memory", &len);

        prop = of_get_flat_dt_prop(node, "ibm,dynamic-memory", &len);
        if (prop) {
                ret = __walk_drmem_v1_lmbs(prop, usm, data, func);
        } else {
                prop = of_get_flat_dt_prop(node, "ibm,dynamic-memory-v2",
                                           &len);
                if (prop)
                        ret = __walk_drmem_v2_lmbs(prop, usm, data, func);
        }

        memblock_dump_all();
        return ret;
}

/*
 * Update the LMB associativity index.
 */
static int update_lmb(struct drmem_lmb *updated_lmb,
                      __maybe_unused const __be32 **usm,
                      __maybe_unused void *data)
{
        struct drmem_lmb *lmb;

        for_each_drmem_lmb(lmb) {
                if (lmb->drc_index != updated_lmb->drc_index)
                        continue;

                lmb->aa_index = updated_lmb->aa_index;
                break;
        }
        return 0;
}

/*
 * Update the LMB associativity index.
 *
 * This needs to be called when the hypervisor is updating the
 * dynamic-reconfiguration-memory node property.
 */
void drmem_update_lmbs(struct property *prop)
{
        /*
         * Don't update the LMBs if triggered by the update done in
         * drmem_update_dt(), the LMB values have been used to the update the DT
         * property in that case.
         */
        if (in_drmem_update)
                return;
        if (!strcmp(prop->name, "ibm,dynamic-memory"))
                __walk_drmem_v1_lmbs(prop->value, NULL, NULL, update_lmb);
        else if (!strcmp(prop->name, "ibm,dynamic-memory-v2"))
                __walk_drmem_v2_lmbs(prop->value, NULL, NULL, update_lmb);
}
#endif

static int init_drmem_lmb_size(struct device_node *dn)
{
        const __be32 *prop;
        int len;

        if (drmem_info->lmb_size)
                return 0;

        prop = of_get_property(dn, "ibm,lmb-size", &len);
        if (!prop || len < n_root_size_cells * sizeof(__be32)) {
                pr_info("Could not determine LMB size\n");
                return -1;
        }

        drmem_info->lmb_size = of_read_number(prop, n_root_size_cells);
        return 0;
}

/*
 * Returns the property linux,drconf-usable-memory if
 * it exists (the property exists only in kexec/kdump kernels,
 * added by kexec-tools)
 */
static const __be32 *of_get_usable_memory(struct device_node *dn)
{
        const __be32 *prop;
        u32 len;

        prop = of_get_property(dn, "linux,drconf-usable-memory", &len);
        if (!prop || len < sizeof(unsigned int))
                return NULL;

        return prop;
}

int walk_drmem_lmbs(struct device_node *dn, void *data,
                    int (*func)(struct drmem_lmb *, const __be32 **, void *))
{
        struct device_node *root = of_find_node_by_path("/");
        const __be32 *prop, *usm;
        int ret = -ENODEV;

        if (!root)
                return ret;

        /* Get the address & size cells */
        n_root_addr_cells = of_n_addr_cells(root);
        n_root_size_cells = of_n_size_cells(root);
        of_node_put(root);

        if (init_drmem_lmb_size(dn))
                return ret;

        usm = of_get_usable_memory(dn);

        prop = of_get_property(dn, "ibm,dynamic-memory", NULL);
        if (prop) {
                ret = __walk_drmem_v1_lmbs(prop, usm, data, func);
        } else {
                prop = of_get_property(dn, "ibm,dynamic-memory-v2", NULL);
                if (prop)
                        ret = __walk_drmem_v2_lmbs(prop, usm, data, func);
        }

        return ret;
}

static void __init init_drmem_v1_lmbs(const __be32 *prop)
{
        struct drmem_lmb *lmb;

        drmem_info->n_lmbs = of_read_number(prop++, 1);
        if (drmem_info->n_lmbs == 0)
                return;

        drmem_info->lmbs = kzalloc_objs(*lmb, drmem_info->n_lmbs);
        if (!drmem_info->lmbs)
                return;

        for_each_drmem_lmb(lmb)
                read_drconf_v1_cell(lmb, &prop);
}

static void __init init_drmem_v2_lmbs(const __be32 *prop)
{
        struct drmem_lmb *lmb;
        struct of_drconf_cell_v2 dr_cell;
        const __be32 *p;
        u32 i, j, lmb_sets;
        int lmb_index;

        lmb_sets = of_read_number(prop++, 1);
        if (lmb_sets == 0)
                return;

        /* first pass, calculate the number of LMBs */
        p = prop;
        for (i = 0; i < lmb_sets; i++) {
                read_drconf_v2_cell(&dr_cell, &p);
                drmem_info->n_lmbs += dr_cell.seq_lmbs;
        }

        drmem_info->lmbs = kzalloc_objs(*lmb, drmem_info->n_lmbs);
        if (!drmem_info->lmbs)
                return;

        /* second pass, read in the LMB information */
        lmb_index = 0;
        p = prop;

        for (i = 0; i < lmb_sets; i++) {
                read_drconf_v2_cell(&dr_cell, &p);

                for (j = 0; j < dr_cell.seq_lmbs; j++) {
                        lmb = &drmem_info->lmbs[lmb_index++];

                        lmb->base_addr = dr_cell.base_addr;
                        dr_cell.base_addr += drmem_info->lmb_size;

                        lmb->drc_index = dr_cell.drc_index;
                        dr_cell.drc_index++;

                        lmb->aa_index = dr_cell.aa_index;
                        lmb->flags = dr_cell.flags;
                }
        }
}

static int __init drmem_init(void)
{
        struct device_node *dn;
        const __be32 *prop;

        dn = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
        if (!dn)
                return 0;

        if (init_drmem_lmb_size(dn)) {
                of_node_put(dn);
                return 0;
        }

        prop = of_get_property(dn, "ibm,dynamic-memory", NULL);
        if (prop) {
                init_drmem_v1_lmbs(prop);
        } else {
                prop = of_get_property(dn, "ibm,dynamic-memory-v2", NULL);
                if (prop)
                        init_drmem_v2_lmbs(prop);
        }

        of_node_put(dn);
        return 0;
}
late_initcall(drmem_init);