// SPDX-License-Identifier: GPL-2.0 or BSD-3-Clause
/*
 * Copyright(c) 2015, 2016 Intel Corporation.
 */

#include "hfi.h"

/* additive distance between non-SOP and SOP space */
#define SOP_DISTANCE (TXE_PIO_SIZE / 2)
#define PIO_BLOCK_MASK (PIO_BLOCK_SIZE - 1)
/* number of QUADWORDs in a block */
#define PIO_BLOCK_QWS (PIO_BLOCK_SIZE / sizeof(u64))

/**
 * pio_copy - copy data block to MMIO space
 * @dd: hfi1 dev data
 * @pbuf: a number of blocks allocated within a PIO send context
 * @pbc: PBC to send
 * @from: source, must be 8 byte aligned
 * @count: number of DWORD (32-bit) quantities to copy from source
 *
 * Copy data from source to PIO Send Buffer memory, 8 bytes at a time.
 * Must always write full BLOCK_SIZE bytes blocks.  The first block must
 * be written to the corresponding SOP=1 address.
 *
 * Known:
 * o pbuf->start always starts on a block boundary
 * o pbuf can wrap only at a block boundary
 */
void pio_copy(struct hfi1_devdata *dd, struct pio_buf *pbuf, u64 pbc,
              const void *from, size_t count)
{
        void __iomem *dest = pbuf->start + SOP_DISTANCE;
        void __iomem *send = dest + PIO_BLOCK_SIZE;
        void __iomem *dend;                     /* 8-byte data end */

        /* write the PBC */
        writeq(pbc, dest);
        dest += sizeof(u64);

        /* calculate where the QWORD data ends - in SOP=1 space */
        dend = dest + ((count >> 1) * sizeof(u64));

        if (dend < send) {
                /*
                 * all QWORD data is within the SOP block, does *not*
                 * reach the end of the SOP block
                 */

                while (dest < dend) {
                        writeq(*(u64 *)from, dest);
                        from += sizeof(u64);
                        dest += sizeof(u64);
                }
                /*
                 * No boundary checks are needed here:
                 * 0. We're not on the SOP block boundary
                 * 1. The possible DWORD dangle will still be within
                 *    the SOP block
                 * 2. We cannot wrap except on a block boundary.
                 */
        } else {
                /* QWORD data extends _to_ or beyond the SOP block */

                /* write 8-byte SOP chunk data */
                while (dest < send) {
                        writeq(*(u64 *)from, dest);
                        from += sizeof(u64);
                        dest += sizeof(u64);
                }
                /* drop out of the SOP range */
                dest -= SOP_DISTANCE;
                dend -= SOP_DISTANCE;

                /*
                 * If the wrap comes before or matches the data end,
                 * copy until until the wrap, then wrap.
                 *
                 * If the data ends at the end of the SOP above and
                 * the buffer wraps, then pbuf->end == dend == dest
                 * and nothing will get written, but we will wrap in
                 * case there is a dangling DWORD.
                 */
                if (pbuf->end <= dend) {
                        while (dest < pbuf->end) {
                                writeq(*(u64 *)from, dest);
                                from += sizeof(u64);
                                dest += sizeof(u64);
                        }

                        dest -= pbuf->sc->size;
                        dend -= pbuf->sc->size;
                }

                /* write 8-byte non-SOP, non-wrap chunk data */
                while (dest < dend) {
                        writeq(*(u64 *)from, dest);
                        from += sizeof(u64);
                        dest += sizeof(u64);
                }
        }
        /* at this point we have wrapped if we are going to wrap */

        /* write dangling u32, if any */
        if (count & 1) {
                union mix val;

                val.val64 = 0;
                val.val32[0] = *(u32 *)from;
                writeq(val.val64, dest);
                dest += sizeof(u64);
        }
        /*
         * fill in rest of block, no need to check pbuf->end
         * as we only wrap on a block boundary
         */
        while (((unsigned long)dest & PIO_BLOCK_MASK) != 0) {
                writeq(0, dest);
                dest += sizeof(u64);
        }

        /* finished with this buffer */
        this_cpu_dec(*pbuf->sc->buffers_allocated);
        preempt_enable();
}

/*
 * Handle carry bytes using shifts and masks.
 *
 * NOTE: the value the unused portion of carry is expected to always be zero.
 */

/*
 * "zero" shift - bit shift used to zero out upper bytes.  Input is
 * the count of LSB bytes to preserve.
 */
#define zshift(x) (8 * (8 - (x)))

/*
 * "merge" shift - bit shift used to merge with carry bytes.  Input is
 * the LSB byte count to move beyond.
 */
#define mshift(x) (8 * (x))

/*
 * Jump copy - no-loop copy for < 8 bytes.
 */
static inline void jcopy(u8 *dest, const u8 *src, u32 n)
{
        switch (n) {
        case 7:
                *dest++ = *src++;
                fallthrough;
        case 6:
                *dest++ = *src++;
                fallthrough;
        case 5:
                *dest++ = *src++;
                fallthrough;
        case 4:
                *dest++ = *src++;
                fallthrough;
        case 3:
                *dest++ = *src++;
                fallthrough;
        case 2:
                *dest++ = *src++;
                fallthrough;
        case 1:
                *dest++ = *src++;
        }
}

/*
 * Read nbytes from "from" and and place them in the low bytes
 * of pbuf->carry.  Other bytes are left as-is.  Any previous
 * value in pbuf->carry is lost.
 *
 * NOTES:
 * o do not read from from if nbytes is zero
 * o from may _not_ be u64 aligned.
 */
static inline void read_low_bytes(struct pio_buf *pbuf, const void *from,
                                  unsigned int nbytes)
{
        pbuf->carry.val64 = 0;
        jcopy(&pbuf->carry.val8[0], from, nbytes);
        pbuf->carry_bytes = nbytes;
}

/*
 * Read nbytes bytes from "from" and put them at the end of pbuf->carry.
 * It is expected that the extra read does not overfill carry.
 *
 * NOTES:
 * o from may _not_ be u64 aligned
 * o nbytes may span a QW boundary
 */
static inline void read_extra_bytes(struct pio_buf *pbuf,
                                    const void *from, unsigned int nbytes)
{
        jcopy(&pbuf->carry.val8[pbuf->carry_bytes], from, nbytes);
        pbuf->carry_bytes += nbytes;
}

/*
 * Write a quad word using parts of pbuf->carry and the next 8 bytes of src.
 * Put the unused part of the next 8 bytes of src into the LSB bytes of
 * pbuf->carry with the upper bytes zeroed..
 *
 * NOTES:
 * o result must keep unused bytes zeroed
 * o src must be u64 aligned
 */
static inline void merge_write8(
        struct pio_buf *pbuf,
        void __iomem *dest,
        const void *src)
{
        u64 new, temp;

        new = *(u64 *)src;
        temp = pbuf->carry.val64 | (new << mshift(pbuf->carry_bytes));
        writeq(temp, dest);
        pbuf->carry.val64 = new >> zshift(pbuf->carry_bytes);
}

/*
 * Write a quad word using all bytes of carry.
 */
static inline void carry8_write8(union mix carry, void __iomem *dest)
{
        writeq(carry.val64, dest);
}

/*
 * Write a quad word using all the valid bytes of carry.  If carry
 * has zero valid bytes, nothing is written.
 * Returns 0 on nothing written, non-zero on quad word written.
 */
static inline int carry_write8(struct pio_buf *pbuf, void __iomem *dest)
{
        if (pbuf->carry_bytes) {
                /* unused bytes are always kept zeroed, so just write */
                writeq(pbuf->carry.val64, dest);
                return 1;
        }

        return 0;
}

/*
 * Segmented PIO Copy - start
 *
 * Start a PIO copy.
 *
 * @pbuf: destination buffer
 * @pbc: the PBC for the PIO buffer
 * @from: data source, QWORD aligned
 * @nbytes: bytes to copy
 */
void seg_pio_copy_start(struct pio_buf *pbuf, u64 pbc,
                        const void *from, size_t nbytes)
{
        void __iomem *dest = pbuf->start + SOP_DISTANCE;
        void __iomem *send = dest + PIO_BLOCK_SIZE;
        void __iomem *dend;                     /* 8-byte data end */

        writeq(pbc, dest);
        dest += sizeof(u64);

        /* calculate where the QWORD data ends - in SOP=1 space */
        dend = dest + ((nbytes >> 3) * sizeof(u64));

        if (dend < send) {
                /*
                 * all QWORD data is within the SOP block, does *not*
                 * reach the end of the SOP block
                 */

                while (dest < dend) {
                        writeq(*(u64 *)from, dest);
                        from += sizeof(u64);
                        dest += sizeof(u64);
                }
                /*
                 * No boundary checks are needed here:
                 * 0. We're not on the SOP block boundary
                 * 1. The possible DWORD dangle will still be within
                 *    the SOP block
                 * 2. We cannot wrap except on a block boundary.
                 */
        } else {
                /* QWORD data extends _to_ or beyond the SOP block */

                /* write 8-byte SOP chunk data */
                while (dest < send) {
                        writeq(*(u64 *)from, dest);
                        from += sizeof(u64);
                        dest += sizeof(u64);
                }
                /* drop out of the SOP range */
                dest -= SOP_DISTANCE;
                dend -= SOP_DISTANCE;

                /*
                 * If the wrap comes before or matches the data end,
                 * copy until until the wrap, then wrap.
                 *
                 * If the data ends at the end of the SOP above and
                 * the buffer wraps, then pbuf->end == dend == dest
                 * and nothing will get written, but we will wrap in
                 * case there is a dangling DWORD.
                 */
                if (pbuf->end <= dend) {
                        while (dest < pbuf->end) {
                                writeq(*(u64 *)from, dest);
                                from += sizeof(u64);
                                dest += sizeof(u64);
                        }

                        dest -= pbuf->sc->size;
                        dend -= pbuf->sc->size;
                }

                /* write 8-byte non-SOP, non-wrap chunk data */
                while (dest < dend) {
                        writeq(*(u64 *)from, dest);
                        from += sizeof(u64);
                        dest += sizeof(u64);
                }
        }
        /* at this point we have wrapped if we are going to wrap */

        /* ...but it doesn't matter as we're done writing */

        /* save dangling bytes, if any */
        read_low_bytes(pbuf, from, nbytes & 0x7);

        pbuf->qw_written = 1 /*PBC*/ + (nbytes >> 3);
}

/*
 * Mid copy helper, "mixed case" - source is 64-bit aligned but carry
 * bytes are non-zero.
 *
 * Whole u64s must be written to the chip, so bytes must be manually merged.
 *
 * @pbuf: destination buffer
 * @from: data source, is QWORD aligned.
 * @nbytes: bytes to copy
 *
 * Must handle nbytes < 8.
 */
static void mid_copy_mix(struct pio_buf *pbuf, const void *from, size_t nbytes)
{
        void __iomem *dest = pbuf->start + (pbuf->qw_written * sizeof(u64));
        void __iomem *dend;                     /* 8-byte data end */
        unsigned long qw_to_write = nbytes >> 3;
        unsigned long bytes_left = nbytes & 0x7;

        /* calculate 8-byte data end */
        dend = dest + (qw_to_write * sizeof(u64));

        if (pbuf->qw_written < PIO_BLOCK_QWS) {
                /*
                 * Still within SOP block.  We don't need to check for
                 * wrap because we are still in the first block and
                 * can only wrap on block boundaries.
                 */
                void __iomem *send;             /* SOP end */
                void __iomem *xend;

                /*
                 * calculate the end of data or end of block, whichever
                 * comes first
                 */
                send = pbuf->start + PIO_BLOCK_SIZE;
                xend = min(send, dend);

                /* shift up to SOP=1 space */
                dest += SOP_DISTANCE;
                xend += SOP_DISTANCE;

                /* write 8-byte chunk data */
                while (dest < xend) {
                        merge_write8(pbuf, dest, from);
                        from += sizeof(u64);
                        dest += sizeof(u64);
                }

                /* shift down to SOP=0 space */
                dest -= SOP_DISTANCE;
        }
        /*
         * At this point dest could be (either, both, or neither):
         * - at dend
         * - at the wrap
         */

        /*
         * If the wrap comes before or matches the data end,
         * copy until until the wrap, then wrap.
         *
         * If dest is at the wrap, we will fall into the if,
         * not do the loop, when wrap.
         *
         * If the data ends at the end of the SOP above and
         * the buffer wraps, then pbuf->end == dend == dest
         * and nothing will get written.
         */
        if (pbuf->end <= dend) {
                while (dest < pbuf->end) {
                        merge_write8(pbuf, dest, from);
                        from += sizeof(u64);
                        dest += sizeof(u64);
                }

                dest -= pbuf->sc->size;
                dend -= pbuf->sc->size;
        }

        /* write 8-byte non-SOP, non-wrap chunk data */
        while (dest < dend) {
                merge_write8(pbuf, dest, from);
                from += sizeof(u64);
                dest += sizeof(u64);
        }

        pbuf->qw_written += qw_to_write;

        /* handle carry and left-over bytes */
        if (pbuf->carry_bytes + bytes_left >= 8) {
                unsigned long nread;

                /* there is enough to fill another qw - fill carry */
                nread = 8 - pbuf->carry_bytes;
                read_extra_bytes(pbuf, from, nread);

                /*
                 * One more write - but need to make sure dest is correct.
                 * Check for wrap and the possibility the write
                 * should be in SOP space.
                 *
                 * The two checks immediately below cannot both be true, hence
                 * the else. If we have wrapped, we cannot still be within the
                 * first block. Conversely, if we are still in the first block,
                 * we cannot have wrapped. We do the wrap check first as that
                 * is more likely.
                 */
                /* adjust if we have wrapped */
                if (dest >= pbuf->end)
                        dest -= pbuf->sc->size;
                /* jump to the SOP range if within the first block */
                else if (pbuf->qw_written < PIO_BLOCK_QWS)
                        dest += SOP_DISTANCE;

                /* flush out full carry */
                carry8_write8(pbuf->carry, dest);
                pbuf->qw_written++;

                /* now adjust and read the rest of the bytes into carry */
                bytes_left -= nread;
                from += nread; /* from is now not aligned */
                read_low_bytes(pbuf, from, bytes_left);
        } else {
                /* not enough to fill another qw, append the rest to carry */
                read_extra_bytes(pbuf, from, bytes_left);
        }
}

/*
 * Mid copy helper, "straight case" - source pointer is 64-bit aligned
 * with no carry bytes.
 *
 * @pbuf: destination buffer
 * @from: data source, is QWORD aligned
 * @nbytes: bytes to copy
 *
 * Must handle nbytes < 8.
 */
static void mid_copy_straight(struct pio_buf *pbuf,
                              const void *from, size_t nbytes)
{
        void __iomem *dest = pbuf->start + (pbuf->qw_written * sizeof(u64));
        void __iomem *dend;                     /* 8-byte data end */

        /* calculate 8-byte data end */
        dend = dest + ((nbytes >> 3) * sizeof(u64));

        if (pbuf->qw_written < PIO_BLOCK_QWS) {
                /*
                 * Still within SOP block.  We don't need to check for
                 * wrap because we are still in the first block and
                 * can only wrap on block boundaries.
                 */
                void __iomem *send;             /* SOP end */
                void __iomem *xend;

                /*
                 * calculate the end of data or end of block, whichever
                 * comes first
                 */
                send = pbuf->start + PIO_BLOCK_SIZE;
                xend = min(send, dend);

                /* shift up to SOP=1 space */
                dest += SOP_DISTANCE;
                xend += SOP_DISTANCE;

                /* write 8-byte chunk data */
                while (dest < xend) {
                        writeq(*(u64 *)from, dest);
                        from += sizeof(u64);
                        dest += sizeof(u64);
                }

                /* shift down to SOP=0 space */
                dest -= SOP_DISTANCE;
        }
        /*
         * At this point dest could be (either, both, or neither):
         * - at dend
         * - at the wrap
         */

        /*
         * If the wrap comes before or matches the data end,
         * copy until until the wrap, then wrap.
         *
         * If dest is at the wrap, we will fall into the if,
         * not do the loop, when wrap.
         *
         * If the data ends at the end of the SOP above and
         * the buffer wraps, then pbuf->end == dend == dest
         * and nothing will get written.
         */
        if (pbuf->end <= dend) {
                while (dest < pbuf->end) {
                        writeq(*(u64 *)from, dest);
                        from += sizeof(u64);
                        dest += sizeof(u64);
                }

                dest -= pbuf->sc->size;
                dend -= pbuf->sc->size;
        }

        /* write 8-byte non-SOP, non-wrap chunk data */
        while (dest < dend) {
                writeq(*(u64 *)from, dest);
                from += sizeof(u64);
                dest += sizeof(u64);
        }

        /* we know carry_bytes was zero on entry to this routine */
        read_low_bytes(pbuf, from, nbytes & 0x7);

        pbuf->qw_written += nbytes >> 3;
}

/*
 * Segmented PIO Copy - middle
 *
 * Must handle any aligned tail and any aligned source with any byte count.
 *
 * @pbuf: a number of blocks allocated within a PIO send context
 * @from: data source
 * @nbytes: number of bytes to copy
 */
void seg_pio_copy_mid(struct pio_buf *pbuf, const void *from, size_t nbytes)
{
        unsigned long from_align = (unsigned long)from & 0x7;

        if (pbuf->carry_bytes + nbytes < 8) {
                /* not enough bytes to fill a QW */
                read_extra_bytes(pbuf, from, nbytes);
                return;
        }

        if (from_align) {
                /* misaligned source pointer - align it */
                unsigned long to_align;

                /* bytes to read to align "from" */
                to_align = 8 - from_align;

                /*
                 * In the advance-to-alignment logic below, we do not need
                 * to check if we are using more than nbytes.  This is because
                 * if we are here, we already know that carry+nbytes will
                 * fill at least one QW.
                 */
                if (pbuf->carry_bytes + to_align < 8) {
                        /* not enough align bytes to fill a QW */
                        read_extra_bytes(pbuf, from, to_align);
                        from += to_align;
                        nbytes -= to_align;
                } else {
                        /* bytes to fill carry */
                        unsigned long to_fill = 8 - pbuf->carry_bytes;
                        /* bytes left over to be read */
                        unsigned long extra = to_align - to_fill;
                        void __iomem *dest;

                        /* fill carry... */
                        read_extra_bytes(pbuf, from, to_fill);
                        from += to_fill;
                        nbytes -= to_fill;
                        /* may not be enough valid bytes left to align */
                        if (extra > nbytes)
                                extra = nbytes;

                        /* ...now write carry */
                        dest = pbuf->start + (pbuf->qw_written * sizeof(u64));

                        /*
                         * The two checks immediately below cannot both be
                         * true, hence the else.  If we have wrapped, we
                         * cannot still be within the first block.
                         * Conversely, if we are still in the first block, we
                         * cannot have wrapped.  We do the wrap check first
                         * as that is more likely.
                         */
                        /* adjust if we've wrapped */
                        if (dest >= pbuf->end)
                                dest -= pbuf->sc->size;
                        /* jump to SOP range if within the first block */
                        else if (pbuf->qw_written < PIO_BLOCK_QWS)
                                dest += SOP_DISTANCE;

                        carry8_write8(pbuf->carry, dest);
                        pbuf->qw_written++;

                        /* read any extra bytes to do final alignment */
                        /* this will overwrite anything in pbuf->carry */
                        read_low_bytes(pbuf, from, extra);
                        from += extra;
                        nbytes -= extra;
                        /*
                         * If no bytes are left, return early - we are done.
                         * NOTE: This short-circuit is *required* because
                         * "extra" may have been reduced in size and "from"
                         * is not aligned, as required when leaving this
                         * if block.
                         */
                        if (nbytes == 0)
                                return;
                }

                /* at this point, from is QW aligned */
        }

        if (pbuf->carry_bytes)
                mid_copy_mix(pbuf, from, nbytes);
        else
                mid_copy_straight(pbuf, from, nbytes);
}

/*
 * Segmented PIO Copy - end
 *
 * Write any remainder (in pbuf->carry) and finish writing the whole block.
 *
 * @pbuf: a number of blocks allocated within a PIO send context
 */
void seg_pio_copy_end(struct pio_buf *pbuf)
{
        void __iomem *dest = pbuf->start + (pbuf->qw_written * sizeof(u64));

        /*
         * The two checks immediately below cannot both be true, hence the
         * else.  If we have wrapped, we cannot still be within the first
         * block.  Conversely, if we are still in the first block, we
         * cannot have wrapped.  We do the wrap check first as that is
         * more likely.
         */
        /* adjust if we have wrapped */
        if (dest >= pbuf->end)
                dest -= pbuf->sc->size;
        /* jump to the SOP range if within the first block */
        else if (pbuf->qw_written < PIO_BLOCK_QWS)
                dest += SOP_DISTANCE;

        /* write final bytes, if any */
        if (carry_write8(pbuf, dest)) {
                dest += sizeof(u64);
                /*
                 * NOTE: We do not need to recalculate whether dest needs
                 * SOP_DISTANCE or not.
                 *
                 * If we are in the first block and the dangle write
                 * keeps us in the same block, dest will need
                 * to retain SOP_DISTANCE in the loop below.
                 *
                 * If we are in the first block and the dangle write pushes
                 * us to the next block, then loop below will not run
                 * and dest is not used.  Hence we do not need to update
                 * it.
                 *
                 * If we are past the first block, then SOP_DISTANCE
                 * was never added, so there is nothing to do.
                 */
        }

        /* fill in rest of block */
        while (((unsigned long)dest & PIO_BLOCK_MASK) != 0) {
                writeq(0, dest);
                dest += sizeof(u64);
        }

        /* finished with this buffer */
        this_cpu_dec(*pbuf->sc->buffers_allocated);
        preempt_enable();
}