/*
 *      linux/drivers/video/bt431.h
 *
 *      Copyright 2003  Thiemo Seufer <seufer@csv.ica.uni-stuttgart.de>
 *      Copyright 2016  Maciej W. Rozycki <macro@linux-mips.org>
 *
 *      This file is subject to the terms and conditions of the GNU General
 *      Public License. See the file COPYING in the main directory of this
 *      archive for more details.
 */
#include <linux/types.h>

#define BT431_CURSOR_SIZE       64

/*
 * Bt431 cursor generator registers, 32-bit aligned.
 * Two twin Bt431 are used on the DECstation's PMAG-AA.
 */
struct bt431_regs {
        volatile u16 addr_lo;
        u16 pad0;
        volatile u16 addr_hi;
        u16 pad1;
        volatile u16 addr_cmap;
        u16 pad2;
        volatile u16 addr_reg;
        u16 pad3;
};

static inline u16 bt431_set_value(u8 val)
{
        return ((val << 8) | (val & 0xff)) & 0xffff;
}

static inline u8 bt431_get_value(u16 val)
{
        return val & 0xff;
}

/*
 * Additional registers addressed indirectly.
 */
#define BT431_REG_CMD           0x0000
#define BT431_REG_CXLO          0x0001
#define BT431_REG_CXHI          0x0002
#define BT431_REG_CYLO          0x0003
#define BT431_REG_CYHI          0x0004
#define BT431_REG_WXLO          0x0005
#define BT431_REG_WXHI          0x0006
#define BT431_REG_WYLO          0x0007
#define BT431_REG_WYHI          0x0008
#define BT431_REG_WWLO          0x0009
#define BT431_REG_WWHI          0x000a
#define BT431_REG_WHLO          0x000b
#define BT431_REG_WHHI          0x000c

#define BT431_REG_CRAM_BASE     0x0000
#define BT431_REG_CRAM_END      0x01ff

/*
 * Command register.
 */
#define BT431_CMD_CURS_ENABLE   0x40
#define BT431_CMD_XHAIR_ENABLE  0x20
#define BT431_CMD_OR_CURSORS    0x10
#define BT431_CMD_XOR_CURSORS   0x00
#define BT431_CMD_1_1_MUX       0x00
#define BT431_CMD_4_1_MUX       0x04
#define BT431_CMD_5_1_MUX       0x08
#define BT431_CMD_xxx_MUX       0x0c
#define BT431_CMD_THICK_1       0x00
#define BT431_CMD_THICK_3       0x01
#define BT431_CMD_THICK_5       0x02
#define BT431_CMD_THICK_7       0x03

static inline void bt431_select_reg(struct bt431_regs *regs, int ir)
{
        /*
         * The compiler splits the write in two bytes without these
         * helper variables.
         */
        volatile u16 *lo = &(regs->addr_lo);
        volatile u16 *hi = &(regs->addr_hi);

        mb();
        *lo = bt431_set_value(ir & 0xff);
        wmb();
        *hi = bt431_set_value((ir >> 8) & 0xff);
}

/* Autoincrement read/write. */
static inline u8 bt431_read_reg_inc(struct bt431_regs *regs)
{
        /*
         * The compiler splits the write in two bytes without the
         * helper variable.
         */
        volatile u16 *r = &(regs->addr_reg);

        mb();
        return bt431_get_value(*r);
}

static inline void bt431_write_reg_inc(struct bt431_regs *regs, u8 value)
{
        /*
         * The compiler splits the write in two bytes without the
         * helper variable.
         */
        volatile u16 *r = &(regs->addr_reg);

        mb();
        *r = bt431_set_value(value);
}

static inline u8 bt431_read_reg(struct bt431_regs *regs, int ir)
{
        bt431_select_reg(regs, ir);
        return bt431_read_reg_inc(regs);
}

static inline void bt431_write_reg(struct bt431_regs *regs, int ir, u8 value)
{
        bt431_select_reg(regs, ir);
        bt431_write_reg_inc(regs, value);
}

/* Autoincremented read/write for the cursor map. */
static inline u16 bt431_read_cmap_inc(struct bt431_regs *regs)
{
        /*
         * The compiler splits the write in two bytes without the
         * helper variable.
         */
        volatile u16 *r = &(regs->addr_cmap);

        mb();
        return *r;
}

static inline void bt431_write_cmap_inc(struct bt431_regs *regs, u16 value)
{
        /*
         * The compiler splits the write in two bytes without the
         * helper variable.
         */
        volatile u16 *r = &(regs->addr_cmap);

        mb();
        *r = value;
}

static inline u16 bt431_read_cmap(struct bt431_regs *regs, int cr)
{
        bt431_select_reg(regs, cr);
        return bt431_read_cmap_inc(regs);
}

static inline void bt431_write_cmap(struct bt431_regs *regs, int cr, u16 value)
{
        bt431_select_reg(regs, cr);
        bt431_write_cmap_inc(regs, value);
}

static inline void bt431_enable_cursor(struct bt431_regs *regs)
{
        bt431_write_reg(regs, BT431_REG_CMD,
                        BT431_CMD_CURS_ENABLE | BT431_CMD_OR_CURSORS
                        | BT431_CMD_4_1_MUX | BT431_CMD_THICK_1);
}

static inline void bt431_erase_cursor(struct bt431_regs *regs)
{
        bt431_write_reg(regs, BT431_REG_CMD, BT431_CMD_4_1_MUX);
}

static inline void bt431_position_cursor(struct bt431_regs *regs, u16 x, u16 y)
{
        /*
         * Magic from the MACH sources.
         *
         * Cx = x + D + H - P
         *  P = 37 if 1:1, 52 if 4:1, 57 if 5:1
         *  D = pixel skew between outdata and external data
         *  H = pixels between HSYNCH falling and active video
         *
         * Cy = y + V - 32
         *  V = scanlines between HSYNCH falling, two or more
         *      clocks after VSYNCH falling, and active video
         */
        x += 412 - 52;
        y += 68 - 32;

        /* Use autoincrement. */
        bt431_select_reg(regs, BT431_REG_CXLO);
        bt431_write_reg_inc(regs, x & 0xff); /* BT431_REG_CXLO */
        bt431_write_reg_inc(regs, (x >> 8) & 0x0f); /* BT431_REG_CXHI */
        bt431_write_reg_inc(regs, y & 0xff); /* BT431_REG_CYLO */
        bt431_write_reg_inc(regs, (y >> 8) & 0x0f); /* BT431_REG_CYHI */
}

static inline void bt431_set_cursor(struct bt431_regs *regs,
                                    const char *data, const char *mask,
                                    u16 rop, u16 width, u16 height)
{
        u16 x, y;
        int i;

        i = 0;
        width = DIV_ROUND_UP(width, 8);
        bt431_select_reg(regs, BT431_REG_CRAM_BASE);
        for (y = 0; y < BT431_CURSOR_SIZE; y++)
                for (x = 0; x < BT431_CURSOR_SIZE / 8; x++) {
                        u16 val = 0;

                        if (y < height && x < width) {
                                val = mask[i];
                                if (rop == ROP_XOR)
                                        val = (val << 8) | (val ^ data[i]);
                                else
                                        val = (val << 8) | (val & data[i]);
                                i++;
                        }
                        bt431_write_cmap_inc(regs, val);
                }
}

static inline void bt431_init_cursor(struct bt431_regs *regs)
{
        /* no crosshair window */
        bt431_select_reg(regs, BT431_REG_WXLO);
        bt431_write_reg_inc(regs, 0x00); /* BT431_REG_WXLO */
        bt431_write_reg_inc(regs, 0x00); /* BT431_REG_WXHI */
        bt431_write_reg_inc(regs, 0x00); /* BT431_REG_WYLO */
        bt431_write_reg_inc(regs, 0x00); /* BT431_REG_WYHI */
        bt431_write_reg_inc(regs, 0x00); /* BT431_REG_WWLO */
        bt431_write_reg_inc(regs, 0x00); /* BT431_REG_WWHI */
        bt431_write_reg_inc(regs, 0x00); /* BT431_REG_WHLO */
        bt431_write_reg_inc(regs, 0x00); /* BT431_REG_WHHI */
}