/*
 * Driver for IBM PowerNV 842 compression accelerator
 *
 * Copyright (C) 2015 Dan Streetman, 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include "nx-842.h"

#include <linux/timer.h>

#include <asm/prom.h>
#include <asm/icswx.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>");
MODULE_DESCRIPTION("842 H/W Compression driver for IBM PowerNV processors");
MODULE_ALIAS_CRYPTO("842");
MODULE_ALIAS_CRYPTO("842-nx");

#define WORKMEM_ALIGN   (CRB_ALIGN)
#define CSB_WAIT_MAX    (5000) /* ms */

struct nx842_workmem {
        /* Below fields must be properly aligned */
        struct coprocessor_request_block crb; /* CRB_ALIGN align */
        struct data_descriptor_entry ddl_in[DDL_LEN_MAX]; /* DDE_ALIGN align */
        struct data_descriptor_entry ddl_out[DDL_LEN_MAX]; /* DDE_ALIGN align */
        /* Above fields must be properly aligned */

        ktime_t start;

        char padding[WORKMEM_ALIGN]; /* unused, to allow alignment */
} __packed __aligned(WORKMEM_ALIGN);

struct nx842_coproc {
        unsigned int chip_id;
        unsigned int ct;
        unsigned int ci;
        struct list_head list;
};

/* no cpu hotplug on powernv, so this list never changes after init */
static LIST_HEAD(nx842_coprocs);
static unsigned int nx842_ct;

/**
 * setup_indirect_dde - Setup an indirect DDE
 *
 * The DDE is setup with the the DDE count, byte count, and address of
 * first direct DDE in the list.
 */
static void setup_indirect_dde(struct data_descriptor_entry *dde,
                               struct data_descriptor_entry *ddl,
                               unsigned int dde_count, unsigned int byte_count)
{
        dde->flags = 0;
        dde->count = dde_count;
        dde->index = 0;
        dde->length = cpu_to_be32(byte_count);
        dde->address = cpu_to_be64(nx842_get_pa(ddl));
}

/**
 * setup_direct_dde - Setup single DDE from buffer
 *
 * The DDE is setup with the buffer and length.  The buffer must be properly
 * aligned.  The used length is returned.
 * Returns:
 *   N    Successfully set up DDE with N bytes
 */
static unsigned int setup_direct_dde(struct data_descriptor_entry *dde,
                                     unsigned long pa, unsigned int len)
{
        unsigned int l = min_t(unsigned int, len, LEN_ON_PAGE(pa));

        dde->flags = 0;
        dde->count = 0;
        dde->index = 0;
        dde->length = cpu_to_be32(l);
        dde->address = cpu_to_be64(pa);

        return l;
}

/**
 * setup_ddl - Setup DDL from buffer
 *
 * Returns:
 *   0          Successfully set up DDL
 */
static int setup_ddl(struct data_descriptor_entry *dde,
                     struct data_descriptor_entry *ddl,
                     unsigned char *buf, unsigned int len,
                     bool in)
{
        unsigned long pa = nx842_get_pa(buf);
        int i, ret, total_len = len;

        if (!IS_ALIGNED(pa, DDE_BUFFER_ALIGN)) {
                pr_debug("%s buffer pa 0x%lx not 0x%x-byte aligned\n",
                         in ? "input" : "output", pa, DDE_BUFFER_ALIGN);
                return -EINVAL;
        }

        /* only need to check last mult; since buffer must be
         * DDE_BUFFER_ALIGN aligned, and that is a multiple of
         * DDE_BUFFER_SIZE_MULT, and pre-last page DDE buffers
         * are guaranteed a multiple of DDE_BUFFER_SIZE_MULT.
         */
        if (len % DDE_BUFFER_LAST_MULT) {
                pr_debug("%s buffer len 0x%x not a multiple of 0x%x\n",
                         in ? "input" : "output", len, DDE_BUFFER_LAST_MULT);
                if (in)
                        return -EINVAL;
                len = round_down(len, DDE_BUFFER_LAST_MULT);
        }

        /* use a single direct DDE */
        if (len <= LEN_ON_PAGE(pa)) {
                ret = setup_direct_dde(dde, pa, len);
                WARN_ON(ret < len);
                return 0;
        }

        /* use the DDL */
        for (i = 0; i < DDL_LEN_MAX && len > 0; i++) {
                ret = setup_direct_dde(&ddl[i], pa, len);
                buf += ret;
                len -= ret;
                pa = nx842_get_pa(buf);
        }

        if (len > 0) {
                pr_debug("0x%x total %s bytes 0x%x too many for DDL.\n",
                         total_len, in ? "input" : "output", len);
                if (in)
                        return -EMSGSIZE;
                total_len -= len;
        }
        setup_indirect_dde(dde, ddl, i, total_len);

        return 0;
}

#define CSB_ERR(csb, msg, ...)                                  \
        pr_err("ERROR: " msg " : %02x %02x %02x %02x %08x\n",   \
               ##__VA_ARGS__, (csb)->flags,                     \
               (csb)->cs, (csb)->cc, (csb)->ce,                 \
               be32_to_cpu((csb)->count))

#define CSB_ERR_ADDR(csb, msg, ...)                             \
        CSB_ERR(csb, msg " at %lx", ##__VA_ARGS__,              \
                (unsigned long)be64_to_cpu((csb)->address))

/**
 * wait_for_csb
 */
static int wait_for_csb(struct nx842_workmem *wmem,
                        struct coprocessor_status_block *csb)
{
        ktime_t start = wmem->start, now = ktime_get();
        ktime_t timeout = ktime_add_ms(start, CSB_WAIT_MAX);

        while (!(ACCESS_ONCE(csb->flags) & CSB_V)) {
                cpu_relax();
                now = ktime_get();
                if (ktime_after(now, timeout))
                        break;
        }

        /* hw has updated csb and output buffer */
        barrier();

        /* check CSB flags */
        if (!(csb->flags & CSB_V)) {
                CSB_ERR(csb, "CSB still not valid after %ld us, giving up",
                        (long)ktime_us_delta(now, start));
                return -ETIMEDOUT;
        }
        if (csb->flags & CSB_F) {
                CSB_ERR(csb, "Invalid CSB format");
                return -EPROTO;
        }
        if (csb->flags & CSB_CH) {
                CSB_ERR(csb, "Invalid CSB chaining state");
                return -EPROTO;
        }

        /* verify CSB completion sequence is 0 */
        if (csb->cs) {
                CSB_ERR(csb, "Invalid CSB completion sequence");
                return -EPROTO;
        }

        /* check CSB Completion Code */
        switch (csb->cc) {
        /* no error */
        case CSB_CC_SUCCESS:
                break;
        case CSB_CC_TPBC_GT_SPBC:
                /* not an error, but the compressed data is
                 * larger than the uncompressed data :(
                 */
                break;

        /* input data errors */
        case CSB_CC_OPERAND_OVERLAP:
                /* input and output buffers overlap */
                CSB_ERR(csb, "Operand Overlap error");
                return -EINVAL;
        case CSB_CC_INVALID_OPERAND:
                CSB_ERR(csb, "Invalid operand");
                return -EINVAL;
        case CSB_CC_NOSPC:
                /* output buffer too small */
                return -ENOSPC;
        case CSB_CC_ABORT:
                CSB_ERR(csb, "Function aborted");
                return -EINTR;
        case CSB_CC_CRC_MISMATCH:
                CSB_ERR(csb, "CRC mismatch");
                return -EINVAL;
        case CSB_CC_TEMPL_INVALID:
                CSB_ERR(csb, "Compressed data template invalid");
                return -EINVAL;
        case CSB_CC_TEMPL_OVERFLOW:
                CSB_ERR(csb, "Compressed data template shows data past end");
                return -EINVAL;

        /* these should not happen */
        case CSB_CC_INVALID_ALIGN:
                /* setup_ddl should have detected this */
                CSB_ERR_ADDR(csb, "Invalid alignment");
                return -EINVAL;
        case CSB_CC_DATA_LENGTH:
                /* setup_ddl should have detected this */
                CSB_ERR(csb, "Invalid data length");
                return -EINVAL;
        case CSB_CC_WR_TRANSLATION:
        case CSB_CC_TRANSLATION:
        case CSB_CC_TRANSLATION_DUP1:
        case CSB_CC_TRANSLATION_DUP2:
        case CSB_CC_TRANSLATION_DUP3:
        case CSB_CC_TRANSLATION_DUP4:
        case CSB_CC_TRANSLATION_DUP5:
        case CSB_CC_TRANSLATION_DUP6:
                /* should not happen, we use physical addrs */
                CSB_ERR_ADDR(csb, "Translation error");
                return -EPROTO;
        case CSB_CC_WR_PROTECTION:
        case CSB_CC_PROTECTION:
        case CSB_CC_PROTECTION_DUP1:
        case CSB_CC_PROTECTION_DUP2:
        case CSB_CC_PROTECTION_DUP3:
        case CSB_CC_PROTECTION_DUP4:
        case CSB_CC_PROTECTION_DUP5:
        case CSB_CC_PROTECTION_DUP6:
                /* should not happen, we use physical addrs */
                CSB_ERR_ADDR(csb, "Protection error");
                return -EPROTO;
        case CSB_CC_PRIVILEGE:
                /* shouldn't happen, we're in HYP mode */
                CSB_ERR(csb, "Insufficient Privilege error");
                return -EPROTO;
        case CSB_CC_EXCESSIVE_DDE:
                /* shouldn't happen, setup_ddl doesn't use many dde's */
                CSB_ERR(csb, "Too many DDEs in DDL");
                return -EINVAL;
        case CSB_CC_TRANSPORT:
                /* shouldn't happen, we setup CRB correctly */
                CSB_ERR(csb, "Invalid CRB");
                return -EINVAL;
        case CSB_CC_SEGMENTED_DDL:
                /* shouldn't happen, setup_ddl creates DDL right */
                CSB_ERR(csb, "Segmented DDL error");
                return -EINVAL;
        case CSB_CC_DDE_OVERFLOW:
                /* shouldn't happen, setup_ddl creates DDL right */
                CSB_ERR(csb, "DDE overflow error");
                return -EINVAL;
        case CSB_CC_SESSION:
                /* should not happen with ICSWX */
                CSB_ERR(csb, "Session violation error");
                return -EPROTO;
        case CSB_CC_CHAIN:
                /* should not happen, we don't use chained CRBs */
                CSB_ERR(csb, "Chained CRB error");
                return -EPROTO;
        case CSB_CC_SEQUENCE:
                /* should not happen, we don't use chained CRBs */
                CSB_ERR(csb, "CRB seqeunce number error");
                return -EPROTO;
        case CSB_CC_UNKNOWN_CODE:
                CSB_ERR(csb, "Unknown subfunction code");
                return -EPROTO;

        /* hardware errors */
        case CSB_CC_RD_EXTERNAL:
        case CSB_CC_RD_EXTERNAL_DUP1:
        case CSB_CC_RD_EXTERNAL_DUP2:
        case CSB_CC_RD_EXTERNAL_DUP3:
                CSB_ERR_ADDR(csb, "Read error outside coprocessor");
                return -EPROTO;
        case CSB_CC_WR_EXTERNAL:
                CSB_ERR_ADDR(csb, "Write error outside coprocessor");
                return -EPROTO;
        case CSB_CC_INTERNAL:
                CSB_ERR(csb, "Internal error in coprocessor");
                return -EPROTO;
        case CSB_CC_PROVISION:
                CSB_ERR(csb, "Storage provision error");
                return -EPROTO;
        case CSB_CC_HW:
                CSB_ERR(csb, "Correctable hardware error");
                return -EPROTO;

        default:
                CSB_ERR(csb, "Invalid CC %d", csb->cc);
                return -EPROTO;
        }

        /* check Completion Extension state */
        if (csb->ce & CSB_CE_TERMINATION) {
                CSB_ERR(csb, "CSB request was terminated");
                return -EPROTO;
        }
        if (csb->ce & CSB_CE_INCOMPLETE) {
                CSB_ERR(csb, "CSB request not complete");
                return -EPROTO;
        }
        if (!(csb->ce & CSB_CE_TPBC)) {
                CSB_ERR(csb, "TPBC not provided, unknown target length");
                return -EPROTO;
        }

        /* successful completion */
        pr_debug_ratelimited("Processed %u bytes in %lu us\n",
                             be32_to_cpu(csb->count),
                             (unsigned long)ktime_us_delta(now, start));

        return 0;
}

/**
 * nx842_powernv_function - compress/decompress data using the 842 algorithm
 *
 * (De)compression provided by the NX842 coprocessor on IBM PowerNV systems.
 * This compresses or decompresses the provided input buffer into the provided
 * output buffer.
 *
 * Upon return from this function @outlen contains the length of the
 * output data.  If there is an error then @outlen will be 0 and an
 * error will be specified by the return code from this function.
 *
 * The @workmem buffer should only be used by one function call at a time.
 *
 * @in: input buffer pointer
 * @inlen: input buffer size
 * @out: output buffer pointer
 * @outlenp: output buffer size pointer
 * @workmem: working memory buffer pointer, size determined by
 *           nx842_powernv_driver.workmem_size
 * @fc: function code, see CCW Function Codes in nx-842.h
 *
 * Returns:
 *   0          Success, output of length @outlenp stored in the buffer at @out
 *   -ENODEV    Hardware unavailable
 *   -ENOSPC    Output buffer is to small
 *   -EMSGSIZE  Input buffer too large
 *   -EINVAL    buffer constraints do not fix nx842_constraints
 *   -EPROTO    hardware error during operation
 *   -ETIMEDOUT hardware did not complete operation in reasonable time
 *   -EINTR     operation was aborted
 */
static int nx842_powernv_function(const unsigned char *in, unsigned int inlen,
                                  unsigned char *out, unsigned int *outlenp,
                                  void *workmem, int fc)
{
        struct coprocessor_request_block *crb;
        struct coprocessor_status_block *csb;
        struct nx842_workmem *wmem;
        int ret;
        u64 csb_addr;
        u32 ccw;
        unsigned int outlen = *outlenp;

        wmem = PTR_ALIGN(workmem, WORKMEM_ALIGN);

        *outlenp = 0;

        /* shoudn't happen, we don't load without a coproc */
        if (!nx842_ct) {
                pr_err_ratelimited("coprocessor CT is 0");
                return -ENODEV;
        }

        crb = &wmem->crb;
        csb = &crb->csb;

        /* Clear any previous values */
        memset(crb, 0, sizeof(*crb));

        /* set up DDLs */
        ret = setup_ddl(&crb->source, wmem->ddl_in,
                        (unsigned char *)in, inlen, true);
        if (ret)
                return ret;
        ret = setup_ddl(&crb->target, wmem->ddl_out,
                        out, outlen, false);
        if (ret)
                return ret;

        /* set up CCW */
        ccw = 0;
        ccw = SET_FIELD(ccw, CCW_CT, nx842_ct);
        ccw = SET_FIELD(ccw, CCW_CI_842, 0); /* use 0 for hw auto-selection */
        ccw = SET_FIELD(ccw, CCW_FC_842, fc);

        /* set up CRB's CSB addr */
        csb_addr = nx842_get_pa(csb) & CRB_CSB_ADDRESS;
        csb_addr |= CRB_CSB_AT; /* Addrs are phys */
        crb->csb_addr = cpu_to_be64(csb_addr);

        wmem->start = ktime_get();

        /* do ICSWX */
        ret = icswx(cpu_to_be32(ccw), crb);

        pr_debug_ratelimited("icswx CR %x ccw %x crb->ccw %x\n", ret,
                             (unsigned int)ccw,
                             (unsigned int)be32_to_cpu(crb->ccw));

        /*
         * NX842 coprocessor sets 3rd bit in CR register with XER[S0].
         * XER[S0] is the integer summary overflow bit which is nothing
         * to do NX. Since this bit can be set with other return values,
         * mask this bit.
         */
        ret &= ~ICSWX_XERS0;

        switch (ret) {
        case ICSWX_INITIATED:
                ret = wait_for_csb(wmem, csb);
                break;
        case ICSWX_BUSY:
                pr_debug_ratelimited("842 Coprocessor busy\n");
                ret = -EBUSY;
                break;
        case ICSWX_REJECTED:
                pr_err_ratelimited("ICSWX rejected\n");
                ret = -EPROTO;
                break;
        }

        if (!ret)
                *outlenp = be32_to_cpu(csb->count);

        return ret;
}

/**
 * nx842_powernv_compress - Compress data using the 842 algorithm
 *
 * Compression provided by the NX842 coprocessor on IBM PowerNV systems.
 * The input buffer is compressed and the result is stored in the
 * provided output buffer.
 *
 * Upon return from this function @outlen contains the length of the
 * compressed data.  If there is an error then @outlen will be 0 and an
 * error will be specified by the return code from this function.
 *
 * @in: input buffer pointer
 * @inlen: input buffer size
 * @out: output buffer pointer
 * @outlenp: output buffer size pointer
 * @workmem: working memory buffer pointer, size determined by
 *           nx842_powernv_driver.workmem_size
 *
 * Returns: see @nx842_powernv_function()
 */
static int nx842_powernv_compress(const unsigned char *in, unsigned int inlen,
                                  unsigned char *out, unsigned int *outlenp,
                                  void *wmem)
{
        return nx842_powernv_function(in, inlen, out, outlenp,
                                      wmem, CCW_FC_842_COMP_CRC);
}

/**
 * nx842_powernv_decompress - Decompress data using the 842 algorithm
 *
 * Decompression provided by the NX842 coprocessor on IBM PowerNV systems.
 * The input buffer is decompressed and the result is stored in the
 * provided output buffer.
 *
 * Upon return from this function @outlen contains the length of the
 * decompressed data.  If there is an error then @outlen will be 0 and an
 * error will be specified by the return code from this function.
 *
 * @in: input buffer pointer
 * @inlen: input buffer size
 * @out: output buffer pointer
 * @outlenp: output buffer size pointer
 * @workmem: working memory buffer pointer, size determined by
 *           nx842_powernv_driver.workmem_size
 *
 * Returns: see @nx842_powernv_function()
 */
static int nx842_powernv_decompress(const unsigned char *in, unsigned int inlen,
                                    unsigned char *out, unsigned int *outlenp,
                                    void *wmem)
{
        return nx842_powernv_function(in, inlen, out, outlenp,
                                      wmem, CCW_FC_842_DECOMP_CRC);
}

static int __init nx842_powernv_probe(struct device_node *dn)
{
        struct nx842_coproc *coproc;
        unsigned int ct, ci;
        int chip_id;

        chip_id = of_get_ibm_chip_id(dn);
        if (chip_id < 0) {
                pr_err("ibm,chip-id missing\n");
                return -EINVAL;
        }

        if (of_property_read_u32(dn, "ibm,842-coprocessor-type", &ct)) {
                pr_err("ibm,842-coprocessor-type missing\n");
                return -EINVAL;
        }

        if (of_property_read_u32(dn, "ibm,842-coprocessor-instance", &ci)) {
                pr_err("ibm,842-coprocessor-instance missing\n");
                return -EINVAL;
        }

        coproc = kmalloc(sizeof(*coproc), GFP_KERNEL);
        if (!coproc)
                return -ENOMEM;

        coproc->chip_id = chip_id;
        coproc->ct = ct;
        coproc->ci = ci;
        INIT_LIST_HEAD(&coproc->list);
        list_add(&coproc->list, &nx842_coprocs);

        pr_info("coprocessor found on chip %d, CT %d CI %d\n", chip_id, ct, ci);

        if (!nx842_ct)
                nx842_ct = ct;
        else if (nx842_ct != ct)
                pr_err("NX842 chip %d, CT %d != first found CT %d\n",
                       chip_id, ct, nx842_ct);

        return 0;
}

static struct nx842_constraints nx842_powernv_constraints = {
        .alignment =    DDE_BUFFER_ALIGN,
        .multiple =     DDE_BUFFER_LAST_MULT,
        .minimum =      DDE_BUFFER_LAST_MULT,
        .maximum =      (DDL_LEN_MAX - 1) * PAGE_SIZE,
};

static struct nx842_driver nx842_powernv_driver = {
        .name =         KBUILD_MODNAME,
        .owner =        THIS_MODULE,
        .workmem_size = sizeof(struct nx842_workmem),
        .constraints =  &nx842_powernv_constraints,
        .compress =     nx842_powernv_compress,
        .decompress =   nx842_powernv_decompress,
};

static int nx842_powernv_crypto_init(struct crypto_tfm *tfm)
{
        return nx842_crypto_init(tfm, &nx842_powernv_driver);
}

static struct crypto_alg nx842_powernv_alg = {
        .cra_name               = "842",
        .cra_driver_name        = "842-nx",
        .cra_priority           = 300,
        .cra_flags              = CRYPTO_ALG_TYPE_COMPRESS,
        .cra_ctxsize            = sizeof(struct nx842_crypto_ctx),
        .cra_module             = THIS_MODULE,
        .cra_init               = nx842_powernv_crypto_init,
        .cra_exit               = nx842_crypto_exit,
        .cra_u                  = { .compress = {
        .coa_compress           = nx842_crypto_compress,
        .coa_decompress         = nx842_crypto_decompress } }
};

static __init int nx842_powernv_init(void)
{
        struct device_node *dn;
        int ret;

        /* verify workmem size/align restrictions */
        BUILD_BUG_ON(WORKMEM_ALIGN % CRB_ALIGN);
        BUILD_BUG_ON(CRB_ALIGN % DDE_ALIGN);
        BUILD_BUG_ON(CRB_SIZE % DDE_ALIGN);
        /* verify buffer size/align restrictions */
        BUILD_BUG_ON(PAGE_SIZE % DDE_BUFFER_ALIGN);
        BUILD_BUG_ON(DDE_BUFFER_ALIGN % DDE_BUFFER_SIZE_MULT);
        BUILD_BUG_ON(DDE_BUFFER_SIZE_MULT % DDE_BUFFER_LAST_MULT);

        for_each_compatible_node(dn, NULL, "ibm,power-nx")
                nx842_powernv_probe(dn);

        if (!nx842_ct)
                return -ENODEV;

        ret = crypto_register_alg(&nx842_powernv_alg);
        if (ret) {
                struct nx842_coproc *coproc, *n;

                list_for_each_entry_safe(coproc, n, &nx842_coprocs, list) {
                        list_del(&coproc->list);
                        kfree(coproc);
                }

                return ret;
        }

        return 0;
}
module_init(nx842_powernv_init);

static void __exit nx842_powernv_exit(void)
{
        struct nx842_coproc *coproc, *n;

        crypto_unregister_alg(&nx842_powernv_alg);

        list_for_each_entry_safe(coproc, n, &nx842_coprocs, list) {
                list_del(&coproc->list);
                kfree(coproc);
        }
}
module_exit(nx842_powernv_exit);