// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Driver for Aeroflex Gaisler SVGACTRL framebuffer device.
 *
 * 2011 (c) Aeroflex Gaisler AB
 *
 * Full documentation of the core can be found here:
 * https://www.gaisler.com/products/grlib/grip.pdf
 *
 * Contributors: Kristoffer Glembo <kristoffer@gaisler.com>
 */

#include <linux/platform_device.h>
#include <linux/dma-mapping.h>
#include <linux/of.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/mm.h>
#include <linux/fb.h>
#include <linux/io.h>

struct grvga_regs {
        u32 status;             /* 0x00 */
        u32 video_length;       /* 0x04 */
        u32 front_porch;        /* 0x08 */
        u32 sync_length;        /* 0x0C */
        u32 line_length;        /* 0x10 */
        u32 fb_pos;             /* 0x14 */
        u32 clk_vector[4];      /* 0x18 */
        u32 clut;               /* 0x20 */
};

struct grvga_par {
        struct grvga_regs *regs;
        u32 color_palette[16];  /* 16 entry pseudo palette used by fbcon in true color mode */
        int clk_sel;
        int fb_alloced;         /* = 1 if framebuffer is allocated in main memory */
};


static const struct fb_videomode grvga_modedb[] = {
    {
        /* 640x480 @ 60 Hz */
        NULL, 60, 640, 480, 40000, 48, 16, 39, 11, 96, 2,
        0, FB_VMODE_NONINTERLACED
    }, {
        /* 800x600 @ 60 Hz */
        NULL, 60, 800, 600, 25000, 88, 40, 23, 1, 128, 4,
        0, FB_VMODE_NONINTERLACED
    }, {
        /* 800x600 @ 72 Hz */
        NULL, 72, 800, 600, 20000, 64, 56, 23, 37, 120, 6,
        0, FB_VMODE_NONINTERLACED
    }, {
        /* 1024x768 @ 60 Hz */
        NULL, 60, 1024, 768, 15385, 160, 24, 29, 3, 136, 6,
        0, FB_VMODE_NONINTERLACED
    }
 };

static const struct fb_fix_screeninfo grvga_fix = {
        .id =           "AG SVGACTRL",
        .type =         FB_TYPE_PACKED_PIXELS,
        .visual =       FB_VISUAL_PSEUDOCOLOR,
        .xpanstep =     0,
        .ypanstep =     1,
        .ywrapstep =    0,
        .accel =        FB_ACCEL_NONE,
};

static int grvga_check_var(struct fb_var_screeninfo *var,
                           struct fb_info *info)
{
        struct grvga_par *par = info->par;
        int i;

        if (!var->xres)
                var->xres = 1;
        if (!var->yres)
                var->yres = 1;
        if (var->bits_per_pixel <= 8)
                var->bits_per_pixel = 8;
        else if (var->bits_per_pixel <= 16)
                var->bits_per_pixel = 16;
        else if (var->bits_per_pixel <= 24)
                var->bits_per_pixel = 24;
        else if (var->bits_per_pixel <= 32)
                var->bits_per_pixel = 32;
        else
                return -EINVAL;

        var->xres_virtual = var->xres;
        var->yres_virtual = 2*var->yres;

        if (info->fix.smem_len) {
                if ((var->yres_virtual*var->xres_virtual*var->bits_per_pixel/8) > info->fix.smem_len)
                        return -ENOMEM;
        }

        /* Which clocks that are available can be read out in these registers */
        for (i = 0; i <= 3 ; i++) {
                if (var->pixclock == par->regs->clk_vector[i])
                        break;
        }
        if (i <= 3)
                par->clk_sel = i;
        else
                return -EINVAL;

        switch (info->var.bits_per_pixel) {
        case 8:
                var->red   = (struct fb_bitfield) {0, 8, 0};      /* offset, length, msb-right */
                var->green = (struct fb_bitfield) {0, 8, 0};
                var->blue  = (struct fb_bitfield) {0, 8, 0};
                var->transp = (struct fb_bitfield) {0, 0, 0};
                break;
        case 16:
                var->red   = (struct fb_bitfield) {11, 5, 0};
                var->green = (struct fb_bitfield) {5, 6, 0};
                var->blue  = (struct fb_bitfield) {0, 5, 0};
                var->transp = (struct fb_bitfield) {0, 0, 0};
                break;
        case 24:
        case 32:
                var->red   = (struct fb_bitfield) {16, 8, 0};
                var->green = (struct fb_bitfield) {8, 8, 0};
                var->blue  = (struct fb_bitfield) {0, 8, 0};
                var->transp = (struct fb_bitfield) {24, 8, 0};
                break;
        default:
                return -EINVAL;
        }

        return 0;
}

static int grvga_set_par(struct fb_info *info)
{

        u32 func = 0;
        struct grvga_par *par = info->par;

        __raw_writel(((info->var.yres - 1) << 16) | (info->var.xres - 1),
                     &par->regs->video_length);

        __raw_writel((info->var.lower_margin << 16) | (info->var.right_margin),
                     &par->regs->front_porch);

        __raw_writel((info->var.vsync_len << 16) | (info->var.hsync_len),
                     &par->regs->sync_length);

        __raw_writel(((info->var.yres + info->var.lower_margin + info->var.upper_margin + info->var.vsync_len - 1) << 16) |
                     (info->var.xres + info->var.right_margin + info->var.left_margin + info->var.hsync_len - 1),
                     &par->regs->line_length);

        switch (info->var.bits_per_pixel) {
        case 8:
                info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
                func = 1;
                break;
        case 16:
                info->fix.visual = FB_VISUAL_TRUECOLOR;
                func = 2;
                break;
        case 24:
        case 32:
                info->fix.visual = FB_VISUAL_TRUECOLOR;
                func = 3;
                break;
        default:
                return -EINVAL;
        }

        __raw_writel((par->clk_sel << 6) | (func << 4) | 1,
                     &par->regs->status);

        info->fix.line_length = (info->var.xres_virtual*info->var.bits_per_pixel)/8;
        return 0;
}

static int grvga_setcolreg(unsigned regno, unsigned red, unsigned green, unsigned blue, unsigned transp, struct fb_info *info)
{
        struct grvga_par *par;
        par = info->par;

        if (regno >= 256)       /* Size of CLUT */
                return -EINVAL;

        if (info->var.grayscale) {
                /* grayscale = 0.30*R + 0.59*G + 0.11*B */
                red = green = blue = (red * 77 + green * 151 + blue * 28) >> 8;
        }



#define CNVT_TOHW(val, width) ((((val)<<(width))+0x7FFF-(val))>>16)

        red    = CNVT_TOHW(red,   info->var.red.length);
        green  = CNVT_TOHW(green, info->var.green.length);
        blue   = CNVT_TOHW(blue,  info->var.blue.length);
        transp = CNVT_TOHW(transp, info->var.transp.length);

#undef CNVT_TOHW

        /* In PSEUDOCOLOR we use the hardware CLUT */
        if (info->fix.visual == FB_VISUAL_PSEUDOCOLOR)
                __raw_writel((regno << 24) | (red << 16) | (green << 8) | blue,
                             &par->regs->clut);

        /* Truecolor uses the pseudo palette */
        else if (info->fix.visual == FB_VISUAL_TRUECOLOR) {
                u32 v;
                if (regno >= 16)
                        return -EINVAL;


                v =     (red    << info->var.red.offset)   |
                        (green  << info->var.green.offset) |
                        (blue   << info->var.blue.offset)  |
                        (transp << info->var.transp.offset);

                ((u32 *) (info->pseudo_palette))[regno] = v;
        }
        return 0;
}

static int grvga_pan_display(struct fb_var_screeninfo *var,
                             struct fb_info *info)
{
        struct grvga_par *par = info->par;
        struct fb_fix_screeninfo *fix = &info->fix;
        u32 base_addr;

        if (var->xoffset != 0)
                return -EINVAL;

        base_addr = fix->smem_start + (var->yoffset * fix->line_length);
        base_addr &= ~3UL;

        /* Set framebuffer base address  */
        __raw_writel(base_addr,
                     &par->regs->fb_pos);

        return 0;
}

static const struct fb_ops grvga_ops = {
        .owner          = THIS_MODULE,
        FB_DEFAULT_IOMEM_OPS,
        .fb_check_var   = grvga_check_var,
        .fb_set_par     = grvga_set_par,
        .fb_setcolreg   = grvga_setcolreg,
        .fb_pan_display = grvga_pan_display,
};

static int grvga_parse_custom(char *options,
                              struct fb_var_screeninfo *screendata)
{
        char *this_opt;
        int count = 0;
        if (!options || !*options)
                return -1;

        while ((this_opt = strsep(&options, " ")) != NULL) {
                if (!*this_opt)
                        continue;

                switch (count) {
                case 0:
                        screendata->pixclock = simple_strtoul(this_opt, NULL, 0);
                        count++;
                        break;
                case 1:
                        screendata->xres = screendata->xres_virtual = simple_strtoul(this_opt, NULL, 0);
                        count++;
                        break;
                case 2:
                        screendata->right_margin = simple_strtoul(this_opt, NULL, 0);
                        count++;
                        break;
                case 3:
                        screendata->hsync_len = simple_strtoul(this_opt, NULL, 0);
                        count++;
                        break;
                case 4:
                        screendata->left_margin = simple_strtoul(this_opt, NULL, 0);
                        count++;
                        break;
                case 5:
                        screendata->yres = screendata->yres_virtual = simple_strtoul(this_opt, NULL, 0);
                        count++;
                        break;
                case 6:
                        screendata->lower_margin = simple_strtoul(this_opt, NULL, 0);
                        count++;
                        break;
                case 7:
                        screendata->vsync_len = simple_strtoul(this_opt, NULL, 0);
                        count++;
                        break;
                case 8:
                        screendata->upper_margin = simple_strtoul(this_opt, NULL, 0);
                        count++;
                        break;
                case 9:
                        screendata->bits_per_pixel = simple_strtoul(this_opt, NULL, 0);
                        count++;
                        break;
                default:
                        return -1;
                }
        }
        screendata->activate  = FB_ACTIVATE_NOW;
        screendata->vmode     = FB_VMODE_NONINTERLACED;
        return 0;
}

static int grvga_probe(struct platform_device *dev)
{
        struct fb_info *info;
        int retval = -ENOMEM;
        unsigned long virtual_start;
        unsigned long grvga_fix_addr = 0;
        unsigned long physical_start = 0;
        unsigned long grvga_mem_size = 0;
        struct grvga_par *par = NULL;
        char *options = NULL, *mode_opt = NULL;

        info = framebuffer_alloc(sizeof(struct grvga_par), &dev->dev);
        if (!info)
                return -ENOMEM;

        /* Expecting: "grvga: modestring, [addr:<framebuffer physical address>], [size:<framebuffer size>]
         *
         * If modestring is custom:<custom mode string> we parse the string which then contains all videoparameters
         * If address is left out, we allocate memory,
         * if size is left out we only allocate enough to support the given mode.
         */
        if (fb_get_options("grvga", &options)) {
                retval = -ENODEV;
                goto free_fb;
        }

        if (!options || !*options)
                options =  "640x480-8@60";

        while (1) {
                char *this_opt = strsep(&options, ",");

                if (!this_opt)
                        break;

                if (!strncmp(this_opt, "custom", 6)) {
                        if (grvga_parse_custom(this_opt, &info->var) < 0) {
                                dev_err(&dev->dev, "Failed to parse custom mode (%s).\n", this_opt);
                                retval = -EINVAL;
                                goto free_fb;
                        }
                } else if (!strncmp(this_opt, "addr", 4))
                        grvga_fix_addr = simple_strtoul(this_opt + 5, NULL, 16);
                else if (!strncmp(this_opt, "size", 4))
                        grvga_mem_size = simple_strtoul(this_opt + 5, NULL, 0);
                else
                        mode_opt = this_opt;
        }

        par = info->par;
        info->fbops = &grvga_ops;
        info->fix = grvga_fix;
        info->pseudo_palette = par->color_palette;
        info->flags = FBINFO_PARTIAL_PAN_OK | FBINFO_HWACCEL_YPAN;
        info->fix.smem_len = grvga_mem_size;

        if (!devm_request_mem_region(&dev->dev, dev->resource[0].start,
                    resource_size(&dev->resource[0]), "grlib-svgactrl regs")) {
                dev_err(&dev->dev, "registers already mapped\n");
                retval = -EBUSY;
                goto free_fb;
        }

        par->regs = of_ioremap(&dev->resource[0], 0,
                               resource_size(&dev->resource[0]),
                               "grlib-svgactrl regs");

        if (!par->regs) {
                dev_err(&dev->dev, "failed to map registers\n");
                retval = -ENOMEM;
                goto free_fb;
        }

        retval = fb_alloc_cmap(&info->cmap, 256, 0);
        if (retval < 0) {
                dev_err(&dev->dev, "failed to allocate mem with fb_alloc_cmap\n");
                retval = -ENOMEM;
                goto unmap_regs;
        }

        if (mode_opt) {
                retval = fb_find_mode(&info->var, info, mode_opt,
                                      grvga_modedb, sizeof(grvga_modedb), &grvga_modedb[0], 8);
                if (!retval || retval == 4) {
                        retval = -EINVAL;
                        goto dealloc_cmap;
                }
        }

        if (!grvga_mem_size)
                grvga_mem_size = info->var.xres_virtual * info->var.yres_virtual * info->var.bits_per_pixel/8;

        if (grvga_fix_addr) {
                /* Got framebuffer base address from argument list */

                physical_start = grvga_fix_addr;

                if (!devm_request_mem_region(&dev->dev, physical_start,
                                             grvga_mem_size, dev->name)) {
                        dev_err(&dev->dev, "failed to request memory region\n");
                        retval = -ENOMEM;
                        goto dealloc_cmap;
                }

                virtual_start = (unsigned long) ioremap(physical_start, grvga_mem_size);

                if (!virtual_start) {
                        dev_err(&dev->dev, "error mapping framebuffer memory\n");
                        retval = -ENOMEM;
                        goto dealloc_cmap;
                }
        } else {        /* Allocate frambuffer memory */

                unsigned long page;

                virtual_start = (unsigned long) __get_free_pages(GFP_DMA,
                                                                 get_order(grvga_mem_size));
                if (!virtual_start) {
                        dev_err(&dev->dev,
                                "unable to allocate framebuffer memory (%lu bytes)\n",
                                grvga_mem_size);
                        retval = -ENOMEM;
                        goto dealloc_cmap;
                }

                physical_start = dma_map_single(&dev->dev, (void *)virtual_start, grvga_mem_size, DMA_TO_DEVICE);

                /* Set page reserved so that mmap will work. This is necessary
                 * since we'll be remapping normal memory.
                 */
                for (page = virtual_start;
                     page < PAGE_ALIGN(virtual_start + grvga_mem_size);
                     page += PAGE_SIZE) {
                        SetPageReserved(virt_to_page(page));
                }

                par->fb_alloced = 1;
        }

        memset((unsigned long *) virtual_start, 0, grvga_mem_size);

        info->screen_base = (char __iomem *) virtual_start;
        info->fix.smem_start = physical_start;
        info->fix.smem_len   = grvga_mem_size;

        dev_set_drvdata(&dev->dev, info);

        dev_info(&dev->dev,
                 "Aeroflex Gaisler framebuffer device (fb%d), %dx%d-%d, using %luK of video memory @ %p\n",
                 info->node, info->var.xres, info->var.yres, info->var.bits_per_pixel,
                 grvga_mem_size >> 10, info->screen_base);

        retval = register_framebuffer(info);
        if (retval < 0) {
                dev_err(&dev->dev, "failed to register framebuffer\n");
                goto free_mem;
        }

        __raw_writel(physical_start, &par->regs->fb_pos);
        __raw_writel(__raw_readl(&par->regs->status) | 1,  /* Enable framebuffer */
                     &par->regs->status);

        return 0;

free_mem:
        if (grvga_fix_addr)
                iounmap((void *)virtual_start);
        else
                kfree((void *)virtual_start);
dealloc_cmap:
        fb_dealloc_cmap(&info->cmap);
unmap_regs:
        of_iounmap(&dev->resource[0], par->regs,
                   resource_size(&dev->resource[0]));
free_fb:
        framebuffer_release(info);

        return retval;
}

static void grvga_remove(struct platform_device *device)
{
        struct fb_info *info = dev_get_drvdata(&device->dev);
        struct grvga_par *par;

        if (info) {
                par = info->par;
                unregister_framebuffer(info);
                fb_dealloc_cmap(&info->cmap);

                of_iounmap(&device->resource[0], par->regs,
                           resource_size(&device->resource[0]));

                if (!par->fb_alloced)
                        iounmap(info->screen_base);
                else
                        kfree((void *)info->screen_base);

                framebuffer_release(info);
        }
}

static struct of_device_id svgactrl_of_match[] = {
        {
                .name = "GAISLER_SVGACTRL",
        },
        {
                .name = "01_063",
        },
        {},
};
MODULE_DEVICE_TABLE(of, svgactrl_of_match);

static struct platform_driver grvga_driver = {
        .driver = {
                .name = "grlib-svgactrl",
                .of_match_table = svgactrl_of_match,
        },
        .probe          = grvga_probe,
        .remove         = grvga_remove,
};

module_platform_driver(grvga_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Aeroflex Gaisler");
MODULE_DESCRIPTION("Aeroflex Gaisler framebuffer device driver");