// SPDX-License-Identifier: GPL-2.0

#define pr_fmt(fmt)     "papr-scm: " fmt

#include <linux/of.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/slab.h>
#include <linux/ndctl.h>
#include <linux/sched.h>
#include <linux/libnvdimm.h>
#include <linux/platform_device.h>
#include <linux/delay.h>

#include <asm/plpar_wrappers.h>

#define BIND_ANY_ADDR (~0ul)

#define PAPR_SCM_DIMM_CMD_MASK \
        ((1ul << ND_CMD_GET_CONFIG_SIZE) | \
         (1ul << ND_CMD_GET_CONFIG_DATA) | \
         (1ul << ND_CMD_SET_CONFIG_DATA))

struct papr_scm_priv {
        struct platform_device *pdev;
        struct device_node *dn;
        uint32_t drc_index;
        uint64_t blocks;
        uint64_t block_size;
        int metadata_size;
        bool is_volatile;

        uint64_t bound_addr;

        struct nvdimm_bus_descriptor bus_desc;
        struct nvdimm_bus *bus;
        struct nvdimm *nvdimm;
        struct resource res;
        struct nd_region *region;
        struct nd_interleave_set nd_set;
};

static int drc_pmem_bind(struct papr_scm_priv *p)
{
        unsigned long ret[PLPAR_HCALL_BUFSIZE];
        uint64_t saved = 0;
        uint64_t token;
        int64_t rc;

        /*
         * When the hypervisor cannot map all the requested memory in a single
         * hcall it returns H_BUSY and we call again with the token until
         * we get H_SUCCESS. Aborting the retry loop before getting H_SUCCESS
         * leave the system in an undefined state, so we wait.
         */
        token = 0;

        do {
                rc = plpar_hcall(H_SCM_BIND_MEM, ret, p->drc_index, 0,
                                p->blocks, BIND_ANY_ADDR, token);
                token = ret[0];
                if (!saved)
                        saved = ret[1];
                cond_resched();
        } while (rc == H_BUSY);

        if (rc)
                return rc;

        p->bound_addr = saved;
        dev_dbg(&p->pdev->dev, "bound drc 0x%x to %pR\n", p->drc_index, &p->res);
        return rc;
}

static void drc_pmem_unbind(struct papr_scm_priv *p)
{
        unsigned long ret[PLPAR_HCALL_BUFSIZE];
        uint64_t token = 0;
        int64_t rc;

        dev_dbg(&p->pdev->dev, "unbind drc 0x%x\n", p->drc_index);

        /* NB: unbind has the same retry requirements as drc_pmem_bind() */
        do {

                /* Unbind of all SCM resources associated with drcIndex */
                rc = plpar_hcall(H_SCM_UNBIND_ALL, ret, H_UNBIND_SCOPE_DRC,
                                 p->drc_index, token);
                token = ret[0];

                /* Check if we are stalled for some time */
                if (H_IS_LONG_BUSY(rc)) {
                        msleep(get_longbusy_msecs(rc));
                        rc = H_BUSY;
                } else if (rc == H_BUSY) {
                        cond_resched();
                }

        } while (rc == H_BUSY);

        if (rc)
                dev_err(&p->pdev->dev, "unbind error: %lld\n", rc);
        else
                dev_dbg(&p->pdev->dev, "unbind drc 0x%x complete\n",
                        p->drc_index);

        return;
}

static int drc_pmem_query_n_bind(struct papr_scm_priv *p)
{
        unsigned long start_addr;
        unsigned long end_addr;
        unsigned long ret[PLPAR_HCALL_BUFSIZE];
        int64_t rc;


        rc = plpar_hcall(H_SCM_QUERY_BLOCK_MEM_BINDING, ret,
                         p->drc_index, 0);
        if (rc)
                goto err_out;
        start_addr = ret[0];

        /* Make sure the full region is bound. */
        rc = plpar_hcall(H_SCM_QUERY_BLOCK_MEM_BINDING, ret,
                         p->drc_index, p->blocks - 1);
        if (rc)
                goto err_out;
        end_addr = ret[0];

        if ((end_addr - start_addr) != ((p->blocks - 1) * p->block_size))
                goto err_out;

        p->bound_addr = start_addr;
        dev_dbg(&p->pdev->dev, "bound drc 0x%x to %pR\n", p->drc_index, &p->res);
        return rc;

err_out:
        dev_info(&p->pdev->dev,
                 "Failed to query, trying an unbind followed by bind");
        drc_pmem_unbind(p);
        return drc_pmem_bind(p);
}


static int papr_scm_meta_get(struct papr_scm_priv *p,
                             struct nd_cmd_get_config_data_hdr *hdr)
{
        unsigned long data[PLPAR_HCALL_BUFSIZE];
        unsigned long offset, data_offset;
        int len, read;
        int64_t ret;

        if ((hdr->in_offset + hdr->in_length) >= p->metadata_size)
                return -EINVAL;

        for (len = hdr->in_length; len; len -= read) {

                data_offset = hdr->in_length - len;
                offset = hdr->in_offset + data_offset;

                if (len >= 8)
                        read = 8;
                else if (len >= 4)
                        read = 4;
                else if (len >= 2)
                        read = 2;
                else
                        read = 1;

                ret = plpar_hcall(H_SCM_READ_METADATA, data, p->drc_index,
                                  offset, read);

                if (ret == H_PARAMETER) /* bad DRC index */
                        return -ENODEV;
                if (ret)
                        return -EINVAL; /* other invalid parameter */

                switch (read) {
                case 8:
                        *(uint64_t *)(hdr->out_buf + data_offset) = be64_to_cpu(data[0]);
                        break;
                case 4:
                        *(uint32_t *)(hdr->out_buf + data_offset) = be32_to_cpu(data[0] & 0xffffffff);
                        break;

                case 2:
                        *(uint16_t *)(hdr->out_buf + data_offset) = be16_to_cpu(data[0] & 0xffff);
                        break;

                case 1:
                        *(uint8_t *)(hdr->out_buf + data_offset) = (data[0] & 0xff);
                        break;
                }
        }
        return 0;
}

static int papr_scm_meta_set(struct papr_scm_priv *p,
                             struct nd_cmd_set_config_hdr *hdr)
{
        unsigned long offset, data_offset;
        int len, wrote;
        unsigned long data;
        __be64 data_be;
        int64_t ret;

        if ((hdr->in_offset + hdr->in_length) >= p->metadata_size)
                return -EINVAL;

        for (len = hdr->in_length; len; len -= wrote) {

                data_offset = hdr->in_length - len;
                offset = hdr->in_offset + data_offset;

                if (len >= 8) {
                        data = *(uint64_t *)(hdr->in_buf + data_offset);
                        data_be = cpu_to_be64(data);
                        wrote = 8;
                } else if (len >= 4) {
                        data = *(uint32_t *)(hdr->in_buf + data_offset);
                        data &= 0xffffffff;
                        data_be = cpu_to_be32(data);
                        wrote = 4;
                } else if (len >= 2) {
                        data = *(uint16_t *)(hdr->in_buf + data_offset);
                        data &= 0xffff;
                        data_be = cpu_to_be16(data);
                        wrote = 2;
                } else {
                        data_be = *(uint8_t *)(hdr->in_buf + data_offset);
                        data_be &= 0xff;
                        wrote = 1;
                }

                ret = plpar_hcall_norets(H_SCM_WRITE_METADATA, p->drc_index,
                                         offset, data_be, wrote);
                if (ret == H_PARAMETER) /* bad DRC index */
                        return -ENODEV;
                if (ret)
                        return -EINVAL; /* other invalid parameter */
        }

        return 0;
}

int papr_scm_ndctl(struct nvdimm_bus_descriptor *nd_desc, struct nvdimm *nvdimm,
                unsigned int cmd, void *buf, unsigned int buf_len, int *cmd_rc)
{
        struct nd_cmd_get_config_size *get_size_hdr;
        struct papr_scm_priv *p;

        /* Only dimm-specific calls are supported atm */
        if (!nvdimm)
                return -EINVAL;

        p = nvdimm_provider_data(nvdimm);

        switch (cmd) {
        case ND_CMD_GET_CONFIG_SIZE:
                get_size_hdr = buf;

                get_size_hdr->status = 0;
                get_size_hdr->max_xfer = 8;
                get_size_hdr->config_size = p->metadata_size;
                *cmd_rc = 0;
                break;

        case ND_CMD_GET_CONFIG_DATA:
                *cmd_rc = papr_scm_meta_get(p, buf);
                break;

        case ND_CMD_SET_CONFIG_DATA:
                *cmd_rc = papr_scm_meta_set(p, buf);
                break;

        default:
                return -EINVAL;
        }

        dev_dbg(&p->pdev->dev, "returned with cmd_rc = %d\n", *cmd_rc);

        return 0;
}

static const struct attribute_group *region_attr_groups[] = {
        &nd_region_attribute_group,
        &nd_device_attribute_group,
        &nd_mapping_attribute_group,
        &nd_numa_attribute_group,
        NULL,
};

static const struct attribute_group *bus_attr_groups[] = {
        &nvdimm_bus_attribute_group,
        NULL,
};

static const struct attribute_group *papr_scm_dimm_groups[] = {
        &nvdimm_attribute_group,
        &nd_device_attribute_group,
        NULL,
};

static inline int papr_scm_node(int node)
{
        int min_dist = INT_MAX, dist;
        int nid, min_node;

        if ((node == NUMA_NO_NODE) || node_online(node))
                return node;

        min_node = first_online_node;
        for_each_online_node(nid) {
                dist = node_distance(node, nid);
                if (dist < min_dist) {
                        min_dist = dist;
                        min_node = nid;
                }
        }
        return min_node;
}

static int papr_scm_nvdimm_init(struct papr_scm_priv *p)
{
        struct device *dev = &p->pdev->dev;
        struct nd_mapping_desc mapping;
        struct nd_region_desc ndr_desc;
        unsigned long dimm_flags;
        int target_nid, online_nid;

        p->bus_desc.ndctl = papr_scm_ndctl;
        p->bus_desc.module = THIS_MODULE;
        p->bus_desc.of_node = p->pdev->dev.of_node;
        p->bus_desc.attr_groups = bus_attr_groups;
        p->bus_desc.provider_name = kstrdup(p->pdev->name, GFP_KERNEL);

        if (!p->bus_desc.provider_name)
                return -ENOMEM;

        p->bus = nvdimm_bus_register(NULL, &p->bus_desc);
        if (!p->bus) {
                dev_err(dev, "Error creating nvdimm bus %pOF\n", p->dn);
                return -ENXIO;
        }

        dimm_flags = 0;
        set_bit(NDD_ALIASING, &dimm_flags);

        p->nvdimm = nvdimm_create(p->bus, p, papr_scm_dimm_groups,
                                dimm_flags, PAPR_SCM_DIMM_CMD_MASK, 0, NULL);
        if (!p->nvdimm) {
                dev_err(dev, "Error creating DIMM object for %pOF\n", p->dn);
                goto err;
        }

        if (nvdimm_bus_check_dimm_count(p->bus, 1))
                goto err;

        /* now add the region */

        memset(&mapping, 0, sizeof(mapping));
        mapping.nvdimm = p->nvdimm;
        mapping.start = 0;
        mapping.size = p->blocks * p->block_size; // XXX: potential overflow?

        memset(&ndr_desc, 0, sizeof(ndr_desc));
        ndr_desc.attr_groups = region_attr_groups;
        target_nid = dev_to_node(&p->pdev->dev);
        online_nid = papr_scm_node(target_nid);
        ndr_desc.numa_node = online_nid;
        ndr_desc.target_node = target_nid;
        ndr_desc.res = &p->res;
        ndr_desc.of_node = p->dn;
        ndr_desc.provider_data = p;
        ndr_desc.mapping = &mapping;
        ndr_desc.num_mappings = 1;
        ndr_desc.nd_set = &p->nd_set;
        set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags);

        if (p->is_volatile)
                p->region = nvdimm_volatile_region_create(p->bus, &ndr_desc);
        else
                p->region = nvdimm_pmem_region_create(p->bus, &ndr_desc);
        if (!p->region) {
                dev_err(dev, "Error registering region %pR from %pOF\n",
                                ndr_desc.res, p->dn);
                goto err;
        }
        if (target_nid != online_nid)
                dev_info(dev, "Region registered with target node %d and online node %d",
                         target_nid, online_nid);

        return 0;

err:    nvdimm_bus_unregister(p->bus);
        kfree(p->bus_desc.provider_name);
        return -ENXIO;
}

static int papr_scm_probe(struct platform_device *pdev)
{
        struct device_node *dn = pdev->dev.of_node;
        u32 drc_index, metadata_size;
        u64 blocks, block_size;
        struct papr_scm_priv *p;
        const char *uuid_str;
        u64 uuid[2];
        int rc;

        /* check we have all the required DT properties */
        if (of_property_read_u32(dn, "ibm,my-drc-index", &drc_index)) {
                dev_err(&pdev->dev, "%pOF: missing drc-index!\n", dn);
                return -ENODEV;
        }

        if (of_property_read_u64(dn, "ibm,block-size", &block_size)) {
                dev_err(&pdev->dev, "%pOF: missing block-size!\n", dn);
                return -ENODEV;
        }

        if (of_property_read_u64(dn, "ibm,number-of-blocks", &blocks)) {
                dev_err(&pdev->dev, "%pOF: missing number-of-blocks!\n", dn);
                return -ENODEV;
        }

        if (of_property_read_string(dn, "ibm,unit-guid", &uuid_str)) {
                dev_err(&pdev->dev, "%pOF: missing unit-guid!\n", dn);
                return -ENODEV;
        }


        p = kzalloc(sizeof(*p), GFP_KERNEL);
        if (!p)
                return -ENOMEM;

        /* optional DT properties */
        of_property_read_u32(dn, "ibm,metadata-size", &metadata_size);

        p->dn = dn;
        p->drc_index = drc_index;
        p->block_size = block_size;
        p->blocks = blocks;
        p->is_volatile = !of_property_read_bool(dn, "ibm,cache-flush-required");

        /* We just need to ensure that set cookies are unique across */
        uuid_parse(uuid_str, (uuid_t *) uuid);
        /*
         * cookie1 and cookie2 are not really little endian
         * we store a little endian representation of the
         * uuid str so that we can compare this with the label
         * area cookie irrespective of the endian config with which
         * the kernel is built.
         */
        p->nd_set.cookie1 = cpu_to_le64(uuid[0]);
        p->nd_set.cookie2 = cpu_to_le64(uuid[1]);

        /* might be zero */
        p->metadata_size = metadata_size;
        p->pdev = pdev;

        /* request the hypervisor to bind this region to somewhere in memory */
        rc = drc_pmem_bind(p);

        /* If phyp says drc memory still bound then force unbound and retry */
        if (rc == H_OVERLAP)
                rc = drc_pmem_query_n_bind(p);

        if (rc != H_SUCCESS) {
                dev_err(&p->pdev->dev, "bind err: %d\n", rc);
                rc = -ENXIO;
                goto err;
        }

        /* setup the resource for the newly bound range */
        p->res.start = p->bound_addr;
        p->res.end   = p->bound_addr + p->blocks * p->block_size - 1;
        p->res.name  = pdev->name;
        p->res.flags = IORESOURCE_MEM;

        rc = papr_scm_nvdimm_init(p);
        if (rc)
                goto err2;

        platform_set_drvdata(pdev, p);

        return 0;

err2:   drc_pmem_unbind(p);
err:    kfree(p);
        return rc;
}

static int papr_scm_remove(struct platform_device *pdev)
{
        struct papr_scm_priv *p = platform_get_drvdata(pdev);

        nvdimm_bus_unregister(p->bus);
        drc_pmem_unbind(p);
        kfree(p);

        return 0;
}

static const struct of_device_id papr_scm_match[] = {
        { .compatible = "ibm,pmemory" },
        { },
};

static struct platform_driver papr_scm_driver = {
        .probe = papr_scm_probe,
        .remove = papr_scm_remove,
        .driver = {
                .name = "papr_scm",
                .owner = THIS_MODULE,
                .of_match_table = papr_scm_match,
        },
};

module_platform_driver(papr_scm_driver);
MODULE_DEVICE_TABLE(of, papr_scm_match);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("IBM Corporation");