// 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 <linux/seq_buf.h>
#include <linux/nd.h>

#include <asm/plpar_wrappers.h>
#include <asm/papr_pdsm.h>
#include <asm/mce.h>
#include <asm/unaligned.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) | \
         (1ul << ND_CMD_CALL))

/* DIMM health bitmap bitmap indicators */
/* SCM device is unable to persist memory contents */
#define PAPR_PMEM_UNARMED                   (1ULL << (63 - 0))
/* SCM device failed to persist memory contents */
#define PAPR_PMEM_SHUTDOWN_DIRTY            (1ULL << (63 - 1))
/* SCM device contents are persisted from previous IPL */
#define PAPR_PMEM_SHUTDOWN_CLEAN            (1ULL << (63 - 2))
/* SCM device contents are not persisted from previous IPL */
#define PAPR_PMEM_EMPTY                     (1ULL << (63 - 3))
/* SCM device memory life remaining is critically low */
#define PAPR_PMEM_HEALTH_CRITICAL           (1ULL << (63 - 4))
/* SCM device will be garded off next IPL due to failure */
#define PAPR_PMEM_HEALTH_FATAL              (1ULL << (63 - 5))
/* SCM contents cannot persist due to current platform health status */
#define PAPR_PMEM_HEALTH_UNHEALTHY          (1ULL << (63 - 6))
/* SCM device is unable to persist memory contents in certain conditions */
#define PAPR_PMEM_HEALTH_NON_CRITICAL       (1ULL << (63 - 7))
/* SCM device is encrypted */
#define PAPR_PMEM_ENCRYPTED                 (1ULL << (63 - 8))
/* SCM device has been scrubbed and locked */
#define PAPR_PMEM_SCRUBBED_AND_LOCKED       (1ULL << (63 - 9))

/* Bits status indicators for health bitmap indicating unarmed dimm */
#define PAPR_PMEM_UNARMED_MASK (PAPR_PMEM_UNARMED |             \
                                PAPR_PMEM_HEALTH_UNHEALTHY)

/* Bits status indicators for health bitmap indicating unflushed dimm */
#define PAPR_PMEM_BAD_SHUTDOWN_MASK (PAPR_PMEM_SHUTDOWN_DIRTY)

/* Bits status indicators for health bitmap indicating unrestored dimm */
#define PAPR_PMEM_BAD_RESTORE_MASK  (PAPR_PMEM_EMPTY)

/* Bit status indicators for smart event notification */
#define PAPR_PMEM_SMART_EVENT_MASK (PAPR_PMEM_HEALTH_CRITICAL | \
                                    PAPR_PMEM_HEALTH_FATAL |    \
                                    PAPR_PMEM_HEALTH_UNHEALTHY)

#define PAPR_SCM_PERF_STATS_EYECATCHER __stringify(SCMSTATS)
#define PAPR_SCM_PERF_STATS_VERSION 0x1

/* Struct holding a single performance metric */
struct papr_scm_perf_stat {
        u8 stat_id[8];
        __be64 stat_val;
} __packed;

/* Struct exchanged between kernel and PHYP for fetching drc perf stats */
struct papr_scm_perf_stats {
        u8 eye_catcher[8];
        /* Should be PAPR_SCM_PERF_STATS_VERSION */
        __be32 stats_version;
        /* Number of stats following */
        __be32 num_statistics;
        /* zero or more performance matrics */
        struct papr_scm_perf_stat scm_statistic[];
} __packed;

/* private struct associated with each region */
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;
        bool hcall_flush_required;

        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;
        struct list_head region_list;

        /* Protect dimm health data from concurrent read/writes */
        struct mutex health_mutex;

        /* Last time the health information of the dimm was updated */
        unsigned long lasthealth_jiffies;

        /* Health information for the dimm */
        u64 health_bitmap;

        /* Holds the last known dirty shutdown counter value */
        u64 dirty_shutdown_counter;

        /* length of the stat buffer as expected by phyp */
        size_t stat_buffer_len;
};

static int papr_scm_pmem_flush(struct nd_region *nd_region,
                               struct bio *bio __maybe_unused)
{
        struct papr_scm_priv *p = nd_region_provider_data(nd_region);
        unsigned long ret_buf[PLPAR_HCALL_BUFSIZE], token = 0;
        long rc;

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

        do {
                rc = plpar_hcall(H_SCM_FLUSH, ret_buf, p->drc_index, token);
                token = ret_buf[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, "flush error: %ld", rc);
                rc = -EIO;
        } else {
                dev_dbg(&p->pdev->dev, "flush drc 0x%x complete", p->drc_index);
        }

        return rc;
}

static LIST_HEAD(papr_nd_regions);
static DEFINE_MUTEX(papr_ndr_lock);

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 0x%lx\n",
                p->drc_index, (unsigned long)saved);
        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 0x%lx\n", p->drc_index, start_addr);
        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);
}

/*
 * Query the Dimm performance stats from PHYP and copy them (if returned) to
 * provided struct papr_scm_perf_stats instance 'stats' that can hold atleast
 * (num_stats + header) bytes.
 * - If buff_stats == NULL the return value is the size in bytes of the buffer
 * needed to hold all supported performance-statistics.
 * - If buff_stats != NULL and num_stats == 0 then we copy all known
 * performance-statistics to 'buff_stat' and expect to be large enough to
 * hold them.
 * - if buff_stats != NULL and num_stats > 0 then copy the requested
 * performance-statistics to buff_stats.
 */
static ssize_t drc_pmem_query_stats(struct papr_scm_priv *p,
                                    struct papr_scm_perf_stats *buff_stats,
                                    unsigned int num_stats)
{
        unsigned long ret[PLPAR_HCALL_BUFSIZE];
        size_t size;
        s64 rc;

        /* Setup the out buffer */
        if (buff_stats) {
                memcpy(buff_stats->eye_catcher,
                       PAPR_SCM_PERF_STATS_EYECATCHER, 8);
                buff_stats->stats_version =
                        cpu_to_be32(PAPR_SCM_PERF_STATS_VERSION);
                buff_stats->num_statistics =
                        cpu_to_be32(num_stats);

                /*
                 * Calculate the buffer size based on num-stats provided
                 * or use the prefetched max buffer length
                 */
                if (num_stats)
                        /* Calculate size from the num_stats */
                        size = sizeof(struct papr_scm_perf_stats) +
                                num_stats * sizeof(struct papr_scm_perf_stat);
                else
                        size = p->stat_buffer_len;
        } else {
                /* In case of no out buffer ignore the size */
                size = 0;
        }

        /* Do the HCALL asking PHYP for info */
        rc = plpar_hcall(H_SCM_PERFORMANCE_STATS, ret, p->drc_index,
                         buff_stats ? virt_to_phys(buff_stats) : 0,
                         size);

        /* Check if the error was due to an unknown stat-id */
        if (rc == H_PARTIAL) {
                dev_err(&p->pdev->dev,
                        "Unknown performance stats, Err:0x%016lX\n", ret[0]);
                return -ENOENT;
        } else if (rc == H_AUTHORITY) {
                dev_info(&p->pdev->dev,
                         "Permission denied while accessing performance stats");
                return -EPERM;
        } else if (rc == H_UNSUPPORTED) {
                dev_dbg(&p->pdev->dev, "Performance stats unsupported\n");
                return -EOPNOTSUPP;
        } else if (rc != H_SUCCESS) {
                dev_err(&p->pdev->dev,
                        "Failed to query performance stats, Err:%lld\n", rc);
                return -EIO;

        } else if (!size) {
                /* Handle case where stat buffer size was requested */
                dev_dbg(&p->pdev->dev,
                        "Performance stats size %ld\n", ret[0]);
                return ret[0];
        }

        /* Successfully fetched the requested stats from phyp */
        dev_dbg(&p->pdev->dev,
                "Performance stats returned %d stats\n",
                be32_to_cpu(buff_stats->num_statistics));
        return 0;
}

/*
 * Issue hcall to retrieve dimm health info and populate papr_scm_priv with the
 * health information.
 */
static int __drc_pmem_query_health(struct papr_scm_priv *p)
{
        unsigned long ret[PLPAR_HCALL_BUFSIZE];
        long rc;

        /* issue the hcall */
        rc = plpar_hcall(H_SCM_HEALTH, ret, p->drc_index);
        if (rc != H_SUCCESS) {
                dev_err(&p->pdev->dev,
                        "Failed to query health information, Err:%ld\n", rc);
                return -ENXIO;
        }

        p->lasthealth_jiffies = jiffies;
        p->health_bitmap = ret[0] & ret[1];

        dev_dbg(&p->pdev->dev,
                "Queried dimm health info. Bitmap:0x%016lx Mask:0x%016lx\n",
                ret[0], ret[1]);

        return 0;
}

/* Min interval in seconds for assuming stable dimm health */
#define MIN_HEALTH_QUERY_INTERVAL 60

/* Query cached health info and if needed call drc_pmem_query_health */
static int drc_pmem_query_health(struct papr_scm_priv *p)
{
        unsigned long cache_timeout;
        int rc;

        /* Protect concurrent modifications to papr_scm_priv */
        rc = mutex_lock_interruptible(&p->health_mutex);
        if (rc)
                return rc;

        /* Jiffies offset for which the health data is assumed to be same */
        cache_timeout = p->lasthealth_jiffies +
                msecs_to_jiffies(MIN_HEALTH_QUERY_INTERVAL * 1000);

        /* Fetch new health info is its older than MIN_HEALTH_QUERY_INTERVAL */
        if (time_after(jiffies, cache_timeout))
                rc = __drc_pmem_query_health(p);
        else
                /* Assume cached health data is valid */
                rc = 0;

        mutex_unlock(&p->health_mutex);
        return rc;
}

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;
}

/*
 * Do a sanity checks on the inputs args to dimm-control function and return
 * '0' if valid. Validation of PDSM payloads happens later in
 * papr_scm_service_pdsm.
 */
static int is_cmd_valid(struct nvdimm *nvdimm, unsigned int cmd, void *buf,
                        unsigned int buf_len)
{
        unsigned long cmd_mask = PAPR_SCM_DIMM_CMD_MASK;
        struct nd_cmd_pkg *nd_cmd;
        struct papr_scm_priv *p;
        enum papr_pdsm pdsm;

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

        /* get the provider data from struct nvdimm */
        p = nvdimm_provider_data(nvdimm);

        if (!test_bit(cmd, &cmd_mask)) {
                dev_dbg(&p->pdev->dev, "Unsupported cmd=%u\n", cmd);
                return -EINVAL;
        }

        /* For CMD_CALL verify pdsm request */
        if (cmd == ND_CMD_CALL) {
                /* Verify the envelope and envelop size */
                if (!buf ||
                    buf_len < (sizeof(struct nd_cmd_pkg) + ND_PDSM_HDR_SIZE)) {
                        dev_dbg(&p->pdev->dev, "Invalid pkg size=%u\n",
                                buf_len);
                        return -EINVAL;
                }

                /* Verify that the nd_cmd_pkg.nd_family is correct */
                nd_cmd = (struct nd_cmd_pkg *)buf;

                if (nd_cmd->nd_family != NVDIMM_FAMILY_PAPR) {
                        dev_dbg(&p->pdev->dev, "Invalid pkg family=0x%llx\n",
                                nd_cmd->nd_family);
                        return -EINVAL;
                }

                pdsm = (enum papr_pdsm)nd_cmd->nd_command;

                /* Verify if the pdsm command is valid */
                if (pdsm <= PAPR_PDSM_MIN || pdsm >= PAPR_PDSM_MAX) {
                        dev_dbg(&p->pdev->dev, "PDSM[0x%x]: Invalid PDSM\n",
                                pdsm);
                        return -EINVAL;
                }

                /* Have enough space to hold returned 'nd_pkg_pdsm' header */
                if (nd_cmd->nd_size_out < ND_PDSM_HDR_SIZE) {
                        dev_dbg(&p->pdev->dev, "PDSM[0x%x]: Invalid payload\n",
                                pdsm);
                        return -EINVAL;
                }
        }

        /* Let the command be further processed */
        return 0;
}

static int papr_pdsm_fuel_gauge(struct papr_scm_priv *p,
                                union nd_pdsm_payload *payload)
{
        int rc, size;
        u64 statval;
        struct papr_scm_perf_stat *stat;
        struct papr_scm_perf_stats *stats;

        /* Silently fail if fetching performance metrics isn't  supported */
        if (!p->stat_buffer_len)
                return 0;

        /* Allocate request buffer enough to hold single performance stat */
        size = sizeof(struct papr_scm_perf_stats) +
                sizeof(struct papr_scm_perf_stat);

        stats = kzalloc(size, GFP_KERNEL);
        if (!stats)
                return -ENOMEM;

        stat = &stats->scm_statistic[0];
        memcpy(&stat->stat_id, "MemLife ", sizeof(stat->stat_id));
        stat->stat_val = 0;

        /* Fetch the fuel gauge and populate it in payload */
        rc = drc_pmem_query_stats(p, stats, 1);
        if (rc < 0) {
                dev_dbg(&p->pdev->dev, "Err(%d) fetching fuel gauge\n", rc);
                goto free_stats;
        }

        statval = be64_to_cpu(stat->stat_val);
        dev_dbg(&p->pdev->dev,
                "Fetched fuel-gauge %llu", statval);
        payload->health.extension_flags |=
                PDSM_DIMM_HEALTH_RUN_GAUGE_VALID;
        payload->health.dimm_fuel_gauge = statval;

        rc = sizeof(struct nd_papr_pdsm_health);

free_stats:
        kfree(stats);
        return rc;
}

/* Add the dirty-shutdown-counter value to the pdsm */
static int papr_pdsm_dsc(struct papr_scm_priv *p,
                         union nd_pdsm_payload *payload)
{
        payload->health.extension_flags |= PDSM_DIMM_DSC_VALID;
        payload->health.dimm_dsc = p->dirty_shutdown_counter;

        return sizeof(struct nd_papr_pdsm_health);
}

/* Fetch the DIMM health info and populate it in provided package. */
static int papr_pdsm_health(struct papr_scm_priv *p,
                            union nd_pdsm_payload *payload)
{
        int rc;

        /* Ensure dimm health mutex is taken preventing concurrent access */
        rc = mutex_lock_interruptible(&p->health_mutex);
        if (rc)
                goto out;

        /* Always fetch upto date dimm health data ignoring cached values */
        rc = __drc_pmem_query_health(p);
        if (rc) {
                mutex_unlock(&p->health_mutex);
                goto out;
        }

        /* update health struct with various flags derived from health bitmap */
        payload->health = (struct nd_papr_pdsm_health) {
                .extension_flags = 0,
                .dimm_unarmed = !!(p->health_bitmap & PAPR_PMEM_UNARMED_MASK),
                .dimm_bad_shutdown = !!(p->health_bitmap & PAPR_PMEM_BAD_SHUTDOWN_MASK),
                .dimm_bad_restore = !!(p->health_bitmap & PAPR_PMEM_BAD_RESTORE_MASK),
                .dimm_scrubbed = !!(p->health_bitmap & PAPR_PMEM_SCRUBBED_AND_LOCKED),
                .dimm_locked = !!(p->health_bitmap & PAPR_PMEM_SCRUBBED_AND_LOCKED),
                .dimm_encrypted = !!(p->health_bitmap & PAPR_PMEM_ENCRYPTED),
                .dimm_health = PAPR_PDSM_DIMM_HEALTHY,
        };

        /* Update field dimm_health based on health_bitmap flags */
        if (p->health_bitmap & PAPR_PMEM_HEALTH_FATAL)
                payload->health.dimm_health = PAPR_PDSM_DIMM_FATAL;
        else if (p->health_bitmap & PAPR_PMEM_HEALTH_CRITICAL)
                payload->health.dimm_health = PAPR_PDSM_DIMM_CRITICAL;
        else if (p->health_bitmap & PAPR_PMEM_HEALTH_UNHEALTHY)
                payload->health.dimm_health = PAPR_PDSM_DIMM_UNHEALTHY;

        /* struct populated hence can release the mutex now */
        mutex_unlock(&p->health_mutex);

        /* Populate the fuel gauge meter in the payload */
        papr_pdsm_fuel_gauge(p, payload);
        /* Populate the dirty-shutdown-counter field */
        papr_pdsm_dsc(p, payload);

        rc = sizeof(struct nd_papr_pdsm_health);

out:
        return rc;
}

/*
 * 'struct pdsm_cmd_desc'
 * Identifies supported PDSMs' expected length of in/out payloads
 * and pdsm service function.
 *
 * size_in      : Size of input payload if any in the PDSM request.
 * size_out     : Size of output payload if any in the PDSM request.
 * service      : Service function for the PDSM request. Return semantics:
 *                rc < 0 : Error servicing PDSM and rc indicates the error.
 *                rc >=0 : Serviced successfully and 'rc' indicate number of
 *                      bytes written to payload.
 */
struct pdsm_cmd_desc {
        u32 size_in;
        u32 size_out;
        int (*service)(struct papr_scm_priv *dimm,
                       union nd_pdsm_payload *payload);
};

/* Holds all supported PDSMs' command descriptors */
static const struct pdsm_cmd_desc __pdsm_cmd_descriptors[] = {
        [PAPR_PDSM_MIN] = {
                .size_in = 0,
                .size_out = 0,
                .service = NULL,
        },
        /* New PDSM command descriptors to be added below */

        [PAPR_PDSM_HEALTH] = {
                .size_in = 0,
                .size_out = sizeof(struct nd_papr_pdsm_health),
                .service = papr_pdsm_health,
        },
        /* Empty */
        [PAPR_PDSM_MAX] = {
                .size_in = 0,
                .size_out = 0,
                .service = NULL,
        },
};

/* Given a valid pdsm cmd return its command descriptor else return NULL */
static inline const struct pdsm_cmd_desc *pdsm_cmd_desc(enum papr_pdsm cmd)
{
        if (cmd >= 0 || cmd < ARRAY_SIZE(__pdsm_cmd_descriptors))
                return &__pdsm_cmd_descriptors[cmd];

        return NULL;
}

/*
 * For a given pdsm request call an appropriate service function.
 * Returns errors if any while handling the pdsm command package.
 */
static int papr_scm_service_pdsm(struct papr_scm_priv *p,
                                 struct nd_cmd_pkg *pkg)
{
        /* Get the PDSM header and PDSM command */
        struct nd_pkg_pdsm *pdsm_pkg = (struct nd_pkg_pdsm *)pkg->nd_payload;
        enum papr_pdsm pdsm = (enum papr_pdsm)pkg->nd_command;
        const struct pdsm_cmd_desc *pdsc;
        int rc;

        /* Fetch corresponding pdsm descriptor for validation and servicing */
        pdsc = pdsm_cmd_desc(pdsm);

        /* Validate pdsm descriptor */
        /* Ensure that reserved fields are 0 */
        if (pdsm_pkg->reserved[0] || pdsm_pkg->reserved[1]) {
                dev_dbg(&p->pdev->dev, "PDSM[0x%x]: Invalid reserved field\n",
                        pdsm);
                return -EINVAL;
        }

        /* If pdsm expects some input, then ensure that the size_in matches */
        if (pdsc->size_in &&
            pkg->nd_size_in != (pdsc->size_in + ND_PDSM_HDR_SIZE)) {
                dev_dbg(&p->pdev->dev, "PDSM[0x%x]: Mismatched size_in=%d\n",
                        pdsm, pkg->nd_size_in);
                return -EINVAL;
        }

        /* If pdsm wants to return data, then ensure that  size_out matches */
        if (pdsc->size_out &&
            pkg->nd_size_out != (pdsc->size_out + ND_PDSM_HDR_SIZE)) {
                dev_dbg(&p->pdev->dev, "PDSM[0x%x]: Mismatched size_out=%d\n",
                        pdsm, pkg->nd_size_out);
                return -EINVAL;
        }

        /* Service the pdsm */
        if (pdsc->service) {
                dev_dbg(&p->pdev->dev, "PDSM[0x%x]: Servicing..\n", pdsm);

                rc = pdsc->service(p, &pdsm_pkg->payload);

                if (rc < 0) {
                        /* error encountered while servicing pdsm */
                        pdsm_pkg->cmd_status = rc;
                        pkg->nd_fw_size = ND_PDSM_HDR_SIZE;
                } else {
                        /* pdsm serviced and 'rc' bytes written to payload */
                        pdsm_pkg->cmd_status = 0;
                        pkg->nd_fw_size = ND_PDSM_HDR_SIZE + rc;
                }
        } else {
                dev_dbg(&p->pdev->dev, "PDSM[0x%x]: Unsupported PDSM request\n",
                        pdsm);
                pdsm_pkg->cmd_status = -ENOENT;
                pkg->nd_fw_size = ND_PDSM_HDR_SIZE;
        }

        return pdsm_pkg->cmd_status;
}

static 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 nd_cmd_pkg *call_pkg = NULL;
        struct papr_scm_priv *p;
        int rc;

        rc = is_cmd_valid(nvdimm, cmd, buf, buf_len);
        if (rc) {
                pr_debug("Invalid cmd=0x%x. Err=%d\n", cmd, rc);
                return rc;
        }

        /* Use a local variable in case cmd_rc pointer is NULL */
        if (!cmd_rc)
                cmd_rc = &rc;

        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;

        case ND_CMD_CALL:
                call_pkg = (struct nd_cmd_pkg *)buf;
                *cmd_rc = papr_scm_service_pdsm(p, call_pkg);
                break;

        default:
                dev_dbg(&p->pdev->dev, "Unknown command = %d\n", cmd);
                return -EINVAL;
        }

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

        return 0;
}

static ssize_t perf_stats_show(struct device *dev,
                               struct device_attribute *attr, char *buf)
{
        int index;
        ssize_t rc;
        struct seq_buf s;
        struct papr_scm_perf_stat *stat;
        struct papr_scm_perf_stats *stats;
        struct nvdimm *dimm = to_nvdimm(dev);
        struct papr_scm_priv *p = nvdimm_provider_data(dimm);

        if (!p->stat_buffer_len)
                return -ENOENT;

        /* Allocate the buffer for phyp where stats are written */
        stats = kzalloc(p->stat_buffer_len, GFP_KERNEL);
        if (!stats)
                return -ENOMEM;

        /* Ask phyp to return all dimm perf stats */
        rc = drc_pmem_query_stats(p, stats, 0);
        if (rc)
                goto free_stats;
        /*
         * Go through the returned output buffer and print stats and
         * values. Since stat_id is essentially a char string of
         * 8 bytes, simply use the string format specifier to print it.
         */
        seq_buf_init(&s, buf, PAGE_SIZE);
        for (index = 0, stat = stats->scm_statistic;
             index < be32_to_cpu(stats->num_statistics);
             ++index, ++stat) {
                seq_buf_printf(&s, "%.8s = 0x%016llX\n",
                               stat->stat_id,
                               be64_to_cpu(stat->stat_val));
        }

free_stats:
        kfree(stats);
        return rc ? rc : (ssize_t)seq_buf_used(&s);
}
static DEVICE_ATTR_ADMIN_RO(perf_stats);

static ssize_t flags_show(struct device *dev,
                          struct device_attribute *attr, char *buf)
{
        struct nvdimm *dimm = to_nvdimm(dev);
        struct papr_scm_priv *p = nvdimm_provider_data(dimm);
        struct seq_buf s;
        u64 health;
        int rc;

        rc = drc_pmem_query_health(p);
        if (rc)
                return rc;

        /* Copy health_bitmap locally, check masks & update out buffer */
        health = READ_ONCE(p->health_bitmap);

        seq_buf_init(&s, buf, PAGE_SIZE);
        if (health & PAPR_PMEM_UNARMED_MASK)
                seq_buf_printf(&s, "not_armed ");

        if (health & PAPR_PMEM_BAD_SHUTDOWN_MASK)
                seq_buf_printf(&s, "flush_fail ");

        if (health & PAPR_PMEM_BAD_RESTORE_MASK)
                seq_buf_printf(&s, "restore_fail ");

        if (health & PAPR_PMEM_ENCRYPTED)
                seq_buf_printf(&s, "encrypted ");

        if (health & PAPR_PMEM_SMART_EVENT_MASK)
                seq_buf_printf(&s, "smart_notify ");

        if (health & PAPR_PMEM_SCRUBBED_AND_LOCKED)
                seq_buf_printf(&s, "scrubbed locked ");

        if (seq_buf_used(&s))
                seq_buf_printf(&s, "\n");

        return seq_buf_used(&s);
}
DEVICE_ATTR_RO(flags);

static ssize_t dirty_shutdown_show(struct device *dev,
                          struct device_attribute *attr, char *buf)
{
        struct nvdimm *dimm = to_nvdimm(dev);
        struct papr_scm_priv *p = nvdimm_provider_data(dimm);

        return sysfs_emit(buf, "%llu\n", p->dirty_shutdown_counter);
}
DEVICE_ATTR_RO(dirty_shutdown);

static umode_t papr_nd_attribute_visible(struct kobject *kobj,
                                         struct attribute *attr, int n)
{
        struct device *dev = kobj_to_dev(kobj);
        struct nvdimm *nvdimm = to_nvdimm(dev);
        struct papr_scm_priv *p = nvdimm_provider_data(nvdimm);

        /* For if perf-stats not available remove perf_stats sysfs */
        if (attr == &dev_attr_perf_stats.attr && p->stat_buffer_len == 0)
                return 0;

        return attr->mode;
}

/* papr_scm specific dimm attributes */
static struct attribute *papr_nd_attributes[] = {
        &dev_attr_flags.attr,
        &dev_attr_perf_stats.attr,
        &dev_attr_dirty_shutdown.attr,
        NULL,
};

static struct attribute_group papr_nd_attribute_group = {
        .name = "papr",
        .is_visible = papr_nd_attribute_visible,
        .attrs = papr_nd_attributes,
};

static const struct attribute_group *papr_nd_attr_groups[] = {
        &papr_nd_attribute_group,
        NULL,
};

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.provider_name = kstrdup(p->pdev->name, GFP_KERNEL);

        /* Set the dimm command family mask to accept PDSMs */
        set_bit(NVDIMM_FAMILY_PAPR, &p->bus_desc.dimm_family_mask);

        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);
                kfree(p->bus_desc.provider_name);
                return -ENXIO;
        }

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

        /*
         * Check if the nvdimm is unarmed. No locking needed as we are still
         * initializing. Ignore error encountered if any.

         */
        __drc_pmem_query_health(p);

        if (p->health_bitmap & PAPR_PMEM_UNARMED_MASK)
                set_bit(NDD_UNARMED, &dimm_flags);

        p->nvdimm = nvdimm_create(p->bus, p, papr_nd_attr_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));
        target_nid = dev_to_node(&p->pdev->dev);
        online_nid = numa_map_to_online_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;

        if (p->hcall_flush_required) {
                set_bit(ND_REGION_ASYNC, &ndr_desc.flags);
                ndr_desc.flush = papr_scm_pmem_flush;
        }

        if (p->is_volatile)
                p->region = nvdimm_volatile_region_create(p->bus, &ndr_desc);
        else {
                set_bit(ND_REGION_PERSIST_MEMCTRL, &ndr_desc.flags);
                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);

        mutex_lock(&papr_ndr_lock);
        list_add_tail(&p->region_list, &papr_nd_regions);
        mutex_unlock(&papr_ndr_lock);

        return 0;

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

static void papr_scm_add_badblock(struct nd_region *region,
                                  struct nvdimm_bus *bus, u64 phys_addr)
{
        u64 aligned_addr = ALIGN_DOWN(phys_addr, L1_CACHE_BYTES);

        if (nvdimm_bus_add_badrange(bus, aligned_addr, L1_CACHE_BYTES)) {
                pr_err("Bad block registration for 0x%llx failed\n", phys_addr);
                return;
        }

        pr_debug("Add memory range (0x%llx - 0x%llx) as bad range\n",
                 aligned_addr, aligned_addr + L1_CACHE_BYTES);

        nvdimm_region_notify(region, NVDIMM_REVALIDATE_POISON);
}

static int handle_mce_ue(struct notifier_block *nb, unsigned long val,
                         void *data)
{
        struct machine_check_event *evt = data;
        struct papr_scm_priv *p;
        u64 phys_addr;
        bool found = false;

        if (evt->error_type != MCE_ERROR_TYPE_UE)
                return NOTIFY_DONE;

        if (list_empty(&papr_nd_regions))
                return NOTIFY_DONE;

        /*
         * The physical address obtained here is PAGE_SIZE aligned, so get the
         * exact address from the effective address
         */
        phys_addr = evt->u.ue_error.physical_address +
                        (evt->u.ue_error.effective_address & ~PAGE_MASK);

        if (!evt->u.ue_error.physical_address_provided ||
            !is_zone_device_page(pfn_to_page(phys_addr >> PAGE_SHIFT)))
                return NOTIFY_DONE;

        /* mce notifier is called from a process context, so mutex is safe */
        mutex_lock(&papr_ndr_lock);
        list_for_each_entry(p, &papr_nd_regions, region_list) {
                if (phys_addr >= p->res.start && phys_addr <= p->res.end) {
                        found = true;
                        break;
                }
        }

        if (found)
                papr_scm_add_badblock(p->region, p->bus, phys_addr);

        mutex_unlock(&papr_ndr_lock);

        return found ? NOTIFY_OK : NOTIFY_DONE;
}

static struct notifier_block mce_ue_nb = {
        .notifier_call = handle_mce_ue
};

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;
        u8 uuid_raw[UUID_SIZE];
        const char *uuid_str;
        ssize_t stat_size;
        uuid_t uuid;
        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;

        /* Initialize the dimm mutex */
        mutex_init(&p->health_mutex);

        /* 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");
        p->hcall_flush_required = of_property_read_bool(dn, "ibm,hcall-flush-required");

        if (of_property_read_u64(dn, "ibm,persistence-failed-count",
                                 &p->dirty_shutdown_counter))
                p->dirty_shutdown_counter = 0;

        /* We just need to ensure that set cookies are unique across */
        uuid_parse(uuid_str, &uuid);

        /*
         * The cookie1 and cookie2 are not really little endian.
         * We store a raw buffer representation of the
         * uuid string so that we can compare this with the label
         * area cookie irrespective of the endian configuration
         * with which the kernel is built.
         *
         * Historically we stored the cookie in the below format.
         * for a uuid string 72511b67-0b3b-42fd-8d1d-5be3cae8bcaa
         *      cookie1 was 0xfd423b0b671b5172
         *      cookie2 was 0xaabce8cae35b1d8d
         */
        export_uuid(uuid_raw, &uuid);
        p->nd_set.cookie1 = get_unaligned_le64(&uuid_raw[0]);
        p->nd_set.cookie2 = get_unaligned_le64(&uuid_raw[8]);

        /* 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;

        /* Try retrieving the stat buffer and see if its supported */
        stat_size = drc_pmem_query_stats(p, NULL, 0);
        if (stat_size > 0) {
                p->stat_buffer_len = stat_size;
                dev_dbg(&p->pdev->dev, "Max perf-stat size %lu-bytes\n",
                        p->stat_buffer_len);
        }

        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);

        mutex_lock(&papr_ndr_lock);
        list_del(&p->region_list);
        mutex_unlock(&papr_ndr_lock);

        nvdimm_bus_unregister(p->bus);
        drc_pmem_unbind(p);
        kfree(p->bus_desc.provider_name);
        kfree(p);

        return 0;
}

static const struct of_device_id papr_scm_match[] = {
        { .compatible = "ibm,pmemory" },
        { .compatible = "ibm,pmemory-v2" },
        { },
};

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

static int __init papr_scm_init(void)
{
        int ret;

        ret = platform_driver_register(&papr_scm_driver);
        if (!ret)
                mce_register_notifier(&mce_ue_nb);

        return ret;
}
module_init(papr_scm_init);

static void __exit papr_scm_exit(void)
{
        mce_unregister_notifier(&mce_ue_nb);
        platform_driver_unregister(&papr_scm_driver);
}
module_exit(papr_scm_exit);

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