/*
 *  tw68_risc.c
 *  Part of the device driver for Techwell 68xx based cards
 *
 *  Much of this code is derived from the cx88 and sa7134 drivers, which
 *  were in turn derived from the bt87x driver.  The original work was by
 *  Gerd Knorr; more recently the code was enhanced by Mauro Carvalho Chehab,
 *  Hans Verkuil, Andy Walls and many others.  Their work is gratefully
 *  acknowledged.  Full credit goes to them - any problems within this code
 *  are mine.
 *
 *  Copyright (C) 2009  William M. Brack
 *
 *  Refactored and updated to the latest v4l core frameworks:
 *
 *  Copyright (C) 2014 Hans Verkuil <hverkuil@xs4all.nl>
 *
 *  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.
 */

#include "tw68.h"

/**
 * tw68_risc_field
 *  @rp:        pointer to current risc program position
 *  @sglist:    pointer to "scatter-gather list" of buffer pointers
 *  @offset:    offset to target memory buffer
 *  @sync_line: 0 -> no sync, 1 -> odd sync, 2 -> even sync
 *  @bpl:       number of bytes per scan line
 *  @padding:   number of bytes of padding to add
 *  @lines:     number of lines in field
 *  @jump:      insert a jump at the start
 */
static __le32 *tw68_risc_field(__le32 *rp, struct scatterlist *sglist,
                            unsigned int offset, u32 sync_line,
                            unsigned int bpl, unsigned int padding,
                            unsigned int lines, bool jump)
{
        struct scatterlist *sg;
        unsigned int line, todo, done;

        if (jump) {
                *(rp++) = cpu_to_le32(RISC_JUMP);
                *(rp++) = 0;
        }

        /* sync instruction */
        if (sync_line == 1)
                *(rp++) = cpu_to_le32(RISC_SYNCO);
        else
                *(rp++) = cpu_to_le32(RISC_SYNCE);
        *(rp++) = 0;

        /* scan lines */
        sg = sglist;
        for (line = 0; line < lines; line++) {
                /* calculate next starting position */
                while (offset && offset >= sg_dma_len(sg)) {
                        offset -= sg_dma_len(sg);
                        sg = sg_next(sg);
                }
                if (bpl <= sg_dma_len(sg) - offset) {
                        /* fits into current chunk */
                        *(rp++) = cpu_to_le32(RISC_LINESTART |
                                              /* (offset<<12) |*/  bpl);
                        *(rp++) = cpu_to_le32(sg_dma_address(sg) + offset);
                        offset += bpl;
                } else {
                        /*
                         * scanline needs to be split.  Put the start in
                         * whatever memory remains using RISC_LINESTART,
                         * then the remainder into following addresses
                         * given by the scatter-gather list.
                         */
                        todo = bpl;     /* one full line to be done */
                        /* first fragment */
                        done = (sg_dma_len(sg) - offset);
                        *(rp++) = cpu_to_le32(RISC_LINESTART |
                                                (7 << 24) |
                                                done);
                        *(rp++) = cpu_to_le32(sg_dma_address(sg) + offset);
                        todo -= done;
                        sg = sg_next(sg);
                        /* succeeding fragments have no offset */
                        while (todo > sg_dma_len(sg)) {
                                *(rp++) = cpu_to_le32(RISC_INLINE |
                                                (done << 12) |
                                                sg_dma_len(sg));
                                *(rp++) = cpu_to_le32(sg_dma_address(sg));
                                todo -= sg_dma_len(sg);
                                sg = sg_next(sg);
                                done += sg_dma_len(sg);
                        }
                        if (todo) {
                                /* final chunk - offset 0, count 'todo' */
                                *(rp++) = cpu_to_le32(RISC_INLINE |
                                                        (done << 12) |
                                                        todo);
                                *(rp++) = cpu_to_le32(sg_dma_address(sg));
                        }
                        offset = todo;
                }
                offset += padding;
        }

        return rp;
}

/**
 * tw68_risc_buffer
 *
 *      This routine is called by tw68-video.  It allocates
 *      memory for the dma controller "program" and then fills in that
 *      memory with the appropriate "instructions".
 *
 *      @pci:           structure with info about the pci
 *                      slot which our device is in.
 *      @buf:           structure with info about the memory
 *                      used for our controller program.
 *      @sglist:        scatter-gather list entry
 *      @top_offset:    offset within the risc program area for the
 *                      first odd frame line
 *      @bottom_offset: offset within the risc program area for the
 *                      first even frame line
 *      @bpl:           number of data bytes per scan line
 *      @padding:       number of extra bytes to add at end of line
 *      @lines:         number of scan lines
 */
int tw68_risc_buffer(struct pci_dev *pci,
                        struct tw68_buf *buf,
                        struct scatterlist *sglist,
                        unsigned int top_offset,
                        unsigned int bottom_offset,
                        unsigned int bpl,
                        unsigned int padding,
                        unsigned int lines)
{
        u32 instructions, fields;
        __le32 *rp;

        fields = 0;
        if (UNSET != top_offset)
                fields++;
        if (UNSET != bottom_offset)
                fields++;
        /*
         * estimate risc mem: worst case is one write per page border +
         * one write per scan line + syncs + 2 jumps (all 2 dwords).
         * Padding can cause next bpl to start close to a page border.
         * First DMA region may be smaller than PAGE_SIZE
         */
        instructions  = fields * (1 + (((bpl + padding) * lines) /
                         PAGE_SIZE) + lines) + 4;
        buf->size = instructions * 8;
        buf->cpu = pci_alloc_consistent(pci, buf->size, &buf->dma);
        if (buf->cpu == NULL)
                return -ENOMEM;

        /* write risc instructions */
        rp = buf->cpu;
        if (UNSET != top_offset)        /* generates SYNCO */
                rp = tw68_risc_field(rp, sglist, top_offset, 1,
                                     bpl, padding, lines, true);
        if (UNSET != bottom_offset)     /* generates SYNCE */
                rp = tw68_risc_field(rp, sglist, bottom_offset, 2,
                                     bpl, padding, lines, top_offset == UNSET);

        /* save pointer to jmp instruction address */
        buf->jmp = rp;
        buf->cpu[1] = cpu_to_le32(buf->dma + 8);
        /* assure risc buffer hasn't overflowed */
        BUG_ON((buf->jmp - buf->cpu + 2) * sizeof(buf->cpu[0]) > buf->size);
        return 0;
}

#if 0
/* ------------------------------------------------------------------ */
/* debug helper code                                                  */

static void tw68_risc_decode(u32 risc, u32 addr)
{
#define RISC_OP(reg)    (((reg) >> 28) & 7)
        static struct instr_details {
                char *name;
                u8 has_data_type;
                u8 has_byte_info;
                u8 has_addr;
        } instr[8] = {
                [RISC_OP(RISC_SYNCO)]     = {"syncOdd", 0, 0, 0},
                [RISC_OP(RISC_SYNCE)]     = {"syncEven", 0, 0, 0},
                [RISC_OP(RISC_JUMP)]      = {"jump", 0, 0, 1},
                [RISC_OP(RISC_LINESTART)] = {"lineStart", 1, 1, 1},
                [RISC_OP(RISC_INLINE)]    = {"inline", 1, 1, 1},
        };
        u32 p;

        p = RISC_OP(risc);
        if (!(risc & 0x80000000) || !instr[p].name) {
                pr_debug("0x%08x [ INVALID ]\n", risc);
                return;
        }
        pr_debug("0x%08x %-9s IRQ=%d",
                risc, instr[p].name, (risc >> 27) & 1);
        if (instr[p].has_data_type)
                pr_debug(" Type=%d", (risc >> 24) & 7);
        if (instr[p].has_byte_info)
                pr_debug(" Start=0x%03x Count=%03u",
                        (risc >> 12) & 0xfff, risc & 0xfff);
        if (instr[p].has_addr)
                pr_debug(" StartAddr=0x%08x", addr);
        pr_debug("\n");
}

void tw68_risc_program_dump(struct tw68_core *core, struct tw68_buf *buf)
{
        const __le32 *addr;

        pr_debug("%s: risc_program_dump: risc=%p, buf->cpu=0x%p, buf->jmp=0x%p\n",
                  core->name, buf, buf->cpu, buf->jmp);
        for (addr = buf->cpu; addr <= buf->jmp; addr += 2)
                tw68_risc_decode(*addr, *(addr+1));
}
#endif