// SPDX-License-Identifier: GPL-2.0-only
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>

#include <asm/setup.h>
#include <asm/irq.h>
#include <asm/amigahw.h>
#include <asm/amigaints.h>
#include <asm/apollohw.h>
#include <linux/fb.h>
#include <linux/module.h>

/* apollo video HW definitions */

/*
 * Control Registers.   IOBASE + $x
 *
 * Note: these are the Memory/IO BASE definitions for a mono card set to the
 * alternate address
 *
 * Control 3A and 3B serve identical functions except that 3A
 * deals with control 1 and 3b deals with Color LUT reg.
 */

#define AP_IOBASE       0x3b0   /* Base address of 1 plane board. */
#define AP_STATUS       isaIO2mem(AP_IOBASE+0)  /* Status register.  Read */
#define AP_WRITE_ENABLE isaIO2mem(AP_IOBASE+0)  /* Write Enable Register Write */
#define AP_DEVICE_ID    isaIO2mem(AP_IOBASE+1)  /* Device ID Register. Read */
#define AP_ROP_1        isaIO2mem(AP_IOBASE+2)  /* Raster Operation reg. Write Word */
#define AP_DIAG_MEM_REQ isaIO2mem(AP_IOBASE+4)  /* Diagnostic Memory Request. Write Word */
#define AP_CONTROL_0    isaIO2mem(AP_IOBASE+8)  /* Control Register 0.  Read/Write */
#define AP_CONTROL_1    isaIO2mem(AP_IOBASE+0xa)        /* Control Register 1.  Read/Write */
#define AP_CONTROL_3A   isaIO2mem(AP_IOBASE+0xe)        /* Control Register 3a. Read/Write */
#define AP_CONTROL_2    isaIO2mem(AP_IOBASE+0xc)        /* Control Register 2. Read/Write */


#define FRAME_BUFFER_START 0x0FA0000
#define FRAME_BUFFER_LEN 0x40000

/* CREG 0 */
#define VECTOR_MODE 0x40        /* 010x.xxxx */
#define DBLT_MODE   0x80        /* 100x.xxxx */
#define NORMAL_MODE 0xE0        /* 111x.xxxx */
#define SHIFT_BITS  0x1F        /* xxx1.1111 */
        /* other bits are Shift value */

/* CREG 1 */
#define AD_BLT      0x80        /* 1xxx.xxxx */
#define NORMAL      0x80 /* 1xxx.xxxx */        /* What is happening here ?? */
#define INVERSE     0x00 /* 0xxx.xxxx */        /* Clearing this reverses the screen */
#define PIX_BLT     0x00        /* 0xxx.xxxx */

#define AD_HIBIT        0x40    /* xIxx.xxxx */

#define ROP_EN          0x10    /* xxx1.xxxx */
#define DST_EQ_SRC      0x00    /* xxx0.xxxx */
#define nRESET_SYNC     0x08    /* xxxx.1xxx */
#define SYNC_ENAB       0x02    /* xxxx.xx1x */

#define BLANK_DISP      0x00    /* xxxx.xxx0 */
#define ENAB_DISP       0x01    /* xxxx.xxx1 */

#define NORM_CREG1      (nRESET_SYNC | SYNC_ENAB | ENAB_DISP)   /* no reset sync */

/* CREG 2 */

/*
 * Following 3 defines are common to 1, 4 and 8 plane.
 */

#define S_DATA_1s   0x00 /* 00xx.xxxx */        /* set source to all 1's -- vector drawing */
#define S_DATA_PIX  0x40 /* 01xx.xxxx */        /* takes source from ls-bits and replicates over 16 bits */
#define S_DATA_PLN  0xC0 /* 11xx.xxxx */        /* normal, each data access =16-bits in
                                                   one plane of image mem */

/* CREG 3A/CREG 3B */
#       define RESET_CREG 0x80  /* 1000.0000 */

/* ROP REG  -  all one nibble */
/*      ********* NOTE : this is used r0,r1,r2,r3 *********** */
#define ROP(r2,r3,r0,r1) ( (U_SHORT)((r0)|((r1)<<4)|((r2)<<8)|((r3)<<12)) )
#define DEST_ZERO               0x0
#define SRC_AND_DEST    0x1
#define SRC_AND_nDEST   0x2
#define SRC                             0x3
#define nSRC_AND_DEST   0x4
#define DEST                    0x5
#define SRC_XOR_DEST    0x6
#define SRC_OR_DEST             0x7
#define SRC_NOR_DEST    0x8
#define SRC_XNOR_DEST   0x9
#define nDEST                   0xA
#define SRC_OR_nDEST    0xB
#define nSRC                    0xC
#define nSRC_OR_DEST    0xD
#define SRC_NAND_DEST   0xE
#define DEST_ONE                0xF

#define SWAP(A) ((A>>8) | ((A&0xff) <<8))

/* frame buffer operations */

static int dnfb_blank(int blank, struct fb_info *info);
static void dnfb_copyarea(struct fb_info *info, const struct fb_copyarea *area);

static const struct fb_ops dn_fb_ops = {
        .owner          = THIS_MODULE,
        __FB_DEFAULT_IOMEM_OPS_RDWR,
        .fb_blank       = dnfb_blank,
        .fb_fillrect    = cfb_fillrect,
        .fb_copyarea    = dnfb_copyarea,
        .fb_imageblit   = cfb_imageblit,
        __FB_DEFAULT_IOMEM_OPS_MMAP,
};

static const struct fb_var_screeninfo dnfb_var = {
        .xres           = 1280,
        .yres           = 1024,
        .xres_virtual   = 2048,
        .yres_virtual   = 1024,
        .bits_per_pixel = 1,
        .height         = -1,
        .width          = -1,
        .vmode          = FB_VMODE_NONINTERLACED,
};

static const struct fb_fix_screeninfo dnfb_fix = {
        .id             = "Apollo Mono",
        .smem_start     = (FRAME_BUFFER_START + IO_BASE),
        .smem_len       = FRAME_BUFFER_LEN,
        .type           = FB_TYPE_PACKED_PIXELS,
        .visual         = FB_VISUAL_MONO10,
        .line_length    = 256,
};

static int dnfb_blank(int blank, struct fb_info *info)
{
        if (blank)
                out_8(AP_CONTROL_3A, 0x0);
        else
                out_8(AP_CONTROL_3A, 0x1);
        return 0;
}

static
void dnfb_copyarea(struct fb_info *info, const struct fb_copyarea *area)
{

        int incr, y_delta, pre_read = 0, x_end, x_word_count;
        uint start_mask, end_mask, dest;
        ushort *src, dummy;
        short i, j;

        incr = (area->dy <= area->sy) ? 1 : -1;

        src = (ushort *)(info->screen_base + area->sy * info->fix.line_length +
                        (area->sx >> 4));
        dest = area->dy * (info->fix.line_length >> 1) + (area->dx >> 4);

        if (incr > 0) {
                y_delta = (info->fix.line_length * 8) - area->sx - area->width;
                x_end = area->dx + area->width - 1;
                x_word_count = (x_end >> 4) - (area->dx >> 4) + 1;
                start_mask = 0xffff0000 >> (area->dx & 0xf);
                end_mask = 0x7ffff >> (x_end & 0xf);
                out_8(AP_CONTROL_0,
                     (((area->dx & 0xf) - (area->sx & 0xf)) % 16) | (0x4 << 5));
                if ((area->dx & 0xf) < (area->sx & 0xf))
                        pre_read = 1;
        } else {
                y_delta = -((info->fix.line_length * 8) - area->sx - area->width);
                x_end = area->dx - area->width + 1;
                x_word_count = (area->dx >> 4) - (x_end >> 4) + 1;
                start_mask = 0x7ffff >> (area->dx & 0xf);
                end_mask = 0xffff0000 >> (x_end & 0xf);
                out_8(AP_CONTROL_0,
                     ((-((area->sx & 0xf) - (area->dx & 0xf))) % 16) |
                     (0x4 << 5));
                if ((area->dx & 0xf) > (area->sx & 0xf))
                        pre_read = 1;
        }

        for (i = 0; i < area->height; i++) {

                out_8(AP_CONTROL_3A, 0xc | (dest >> 16));

                if (pre_read) {
                        dummy = *src;
                        src += incr;
                }

                if (x_word_count) {
                        out_8(AP_WRITE_ENABLE, start_mask);
                        *src = dest;
                        src += incr;
                        dest += incr;
                        out_8(AP_WRITE_ENABLE, 0);

                        for (j = 1; j < (x_word_count - 1); j++) {
                                *src = dest;
                                src += incr;
                                dest += incr;
                        }

                        out_8(AP_WRITE_ENABLE, start_mask);
                        *src = dest;
                        dest += incr;
                        src += incr;
                } else {
                        out_8(AP_WRITE_ENABLE, start_mask | end_mask);
                        *src = dest;
                        dest += incr;
                        src += incr;
                }
                src += (y_delta / 16);
                dest += (y_delta / 16);
        }
        out_8(AP_CONTROL_0, NORMAL_MODE);
}

/*
 * Initialization
 */

static int dnfb_probe(struct platform_device *dev)
{
        struct fb_info *info;
        int err = 0;

        info = framebuffer_alloc(0, &dev->dev);
        if (!info)
                return -ENOMEM;

        info->fbops = &dn_fb_ops;
        info->fix = dnfb_fix;
        info->var = dnfb_var;
        info->var.red.length = 1;
        info->var.red.offset = 0;
        info->var.green = info->var.blue = info->var.red;
        info->screen_base = (u_char *) info->fix.smem_start;

        err = fb_alloc_cmap(&info->cmap, 2, 0);
        if (err < 0)
                goto release_framebuffer;

        err = register_framebuffer(info);
        if (err < 0) {
                fb_dealloc_cmap(&info->cmap);
                goto release_framebuffer;
        }
        platform_set_drvdata(dev, info);

        /* now we have registered we can safely setup the hardware */
        out_8(AP_CONTROL_3A, RESET_CREG);
        out_be16(AP_WRITE_ENABLE, 0x0);
        out_8(AP_CONTROL_0, NORMAL_MODE);
        out_8(AP_CONTROL_1, (AD_BLT | DST_EQ_SRC | NORM_CREG1));
        out_8(AP_CONTROL_2, S_DATA_PLN);
        out_be16(AP_ROP_1, SWAP(0x3));

        printk("apollo frame buffer alive and kicking !\n");
        return err;

release_framebuffer:
        framebuffer_release(info);
        return err;
}

static struct platform_driver dnfb_driver = {
        .probe  = dnfb_probe,
        .driver = {
                .name   = "dnfb",
        },
};

static struct platform_device dnfb_device = {
        .name   = "dnfb",
};

static int __init dnfb_init(void)
{
        int ret;

        if (!MACH_IS_APOLLO)
                return -ENODEV;

        if (fb_get_options("dnfb", NULL))
                return -ENODEV;

        ret = platform_driver_register(&dnfb_driver);

        if (!ret) {
                ret = platform_device_register(&dnfb_device);
                if (ret)
                        platform_driver_unregister(&dnfb_driver);
        }
        return ret;
}

module_init(dnfb_init);

MODULE_LICENSE("GPL");