/*
   * Simplest possible simple frame-buffer driver, as a platform device
   *
   * Copyright (c) 2013, Stephen Warren
   *
   * Based on q40fb.c, which was:
   * Copyright (C) 2001 Richard Zidlicky <rz@linux-m68k.org>
   *
   * Also based on offb.c, which was:
   * Copyright (C) 1997 Geert Uytterhoeven
   * Copyright (C) 1996 Paul Mackerras
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms and conditions of the GNU General Public License,
   * version 2, as published by the Free Software Foundation.
   *
   * This program is distributed in the hope 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 <linux/errno.h>
  #include <linux/fb.h>
  #include <linux/io.h>
  #include <linux/module.h>
  #include <linux/platform_data/simplefb.h>
  #include <linux/platform_device.h>
  
  static struct fb_fix_screeninfo simplefb_fix = {
  	.id		= "simple",
  	.type		= FB_TYPE_PACKED_PIXELS,
  	.visual		= FB_VISUAL_TRUECOLOR,
  	.accel		= FB_ACCEL_NONE,
  };
  
  static struct fb_var_screeninfo simplefb_var = {
  	.height		= -1,
  	.width		= -1,
  	.activate	= FB_ACTIVATE_NOW,
  	.vmode		= FB_VMODE_NONINTERLACED,
  };
  
  static int simplefb_setcolreg(u_int regno, u_int red, u_int green, u_int blue,
  			      u_int transp, struct fb_info *info)
  {
  	u32 *pal = info->pseudo_palette;
  	u32 cr = red >> (16 - info->var.red.length);
  	u32 cg = green >> (16 - info->var.green.length);
  	u32 cb = blue >> (16 - info->var.blue.length);
  	u32 value;
  
  	if (regno >= 16)
  		return -EINVAL;
  
  	value = (cr << info->var.red.offset) |
  		(cg << info->var.green.offset) |
  		(cb << info->var.blue.offset);
  	if (info->var.transp.length > 0) {
  		u32 mask = (1 << info->var.transp.length) - 1;
  		mask <<= info->var.transp.offset;
  		value |= mask;
  	}
  	pal[regno] = value;
  
  	return 0;
  }
  
  static void simplefb_destroy(struct fb_info *info)
  {
  	if (info->screen_base)
  		iounmap(info->screen_base);
  }
  
  static struct fb_ops simplefb_ops = {
  	.owner		= THIS_MODULE,
  	.fb_destroy	= simplefb_destroy,
  	.fb_setcolreg	= simplefb_setcolreg,
  	.fb_fillrect	= cfb_fillrect,
  	.fb_copyarea	= cfb_copyarea,
  	.fb_imageblit	= cfb_imageblit,
  };
  
  static struct simplefb_format simplefb_formats[] = SIMPLEFB_FORMATS;
  
  struct simplefb_params {
  	u32 width;
  	u32 height;
  	u32 stride;
  	struct simplefb_format *format;
  };
  
  static int simplefb_parse_dt(struct platform_device *pdev,
  			   struct simplefb_params *params)
  {
  	struct device_node *np = pdev->dev.of_node;
  	int ret;
  	const char *format;
  	int i;
  
  	ret = of_property_read_u32(np, "width", &params->width);
  	if (ret) {
  		dev_err(&pdev->dev, "Can't parse width property
  ");
  		return ret;
  	}
  
  	ret = of_property_read_u32(np, "height", &params->height);
  	if (ret) {
  		dev_err(&pdev->dev, "Can't parse height property
  ");
  		return ret;
  	}
  
  	ret = of_property_read_u32(np, "stride", &params->stride);
  	if (ret) {
  		dev_err(&pdev->dev, "Can't parse stride property
  ");
  		return ret;
  	}
  
  	ret = of_property_read_string(np, "format", &format);
  	if (ret) {
  		dev_err(&pdev->dev, "Can't parse format property
  ");
  		return ret;
  	}
  	params->format = NULL;
  	for (i = 0; i < ARRAY_SIZE(simplefb_formats); i++) {
  		if (strcmp(format, simplefb_formats[i].name))
  			continue;
  		params->format = &simplefb_formats[i];
  		break;
  	}
  	if (!params->format) {
  		dev_err(&pdev->dev, "Invalid format value
  ");
  		return -EINVAL;
  	}
  
  	return 0;
  }
  
  static int simplefb_parse_pd(struct platform_device *pdev,
  			     struct simplefb_params *params)
  {
  	struct simplefb_platform_data *pd = dev_get_platdata(&pdev->dev);
  	int i;
  
  	params->width = pd->width;
  	params->height = pd->height;
  	params->stride = pd->stride;
  
  	params->format = NULL;
  	for (i = 0; i < ARRAY_SIZE(simplefb_formats); i++) {
  		if (strcmp(pd->format, simplefb_formats[i].name))
  			continue;
  
  		params->format = &simplefb_formats[i];
  		break;
  	}
  
  	if (!params->format) {
  		dev_err(&pdev->dev, "Invalid format value
  ");
  		return -EINVAL;
  	}
  
  	return 0;
  }
  
  static int simplefb_probe(struct platform_device *pdev)
  {
  	int ret;
  	struct simplefb_params params;
  	struct fb_info *info;
  	struct resource *mem;
  
  	if (fb_get_options("simplefb", NULL))
  		return -ENODEV;
  
  	ret = -ENODEV;
  	if (dev_get_platdata(&pdev->dev))
  		ret = simplefb_parse_pd(pdev, &params);
  	else if (pdev->dev.of_node)
  		ret = simplefb_parse_dt(pdev, &params);
  
  	if (ret)
  		return ret;
  
  	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (!mem) {
  		dev_err(&pdev->dev, "No memory resource
  ");
  		return -EINVAL;
  	}
  
  	info = framebuffer_alloc(sizeof(u32) * 16, &pdev->dev);
  	if (!info)
  		return -ENOMEM;
  	platform_set_drvdata(pdev, info);
  
  	info->fix = simplefb_fix;
  	info->fix.smem_start = mem->start;
  	info->fix.smem_len = resource_size(mem);
  	info->fix.line_length = params.stride;
  
  	info->var = simplefb_var;
  	info->var.xres = params.width;
  	info->var.yres = params.height;
  	info->var.xres_virtual = params.width;
  	info->var.yres_virtual = params.height;
  	info->var.bits_per_pixel = params.format->bits_per_pixel;
  	info->var.red = params.format->red;
  	info->var.green = params.format->green;
  	info->var.blue = params.format->blue;
  	info->var.transp = params.format->transp;
  
  	info->apertures = alloc_apertures(1);
  	if (!info->apertures) {
  		framebuffer_release(info);
  		return -ENOMEM;
  	}
  	info->apertures->ranges[0].base = info->fix.smem_start;
  	info->apertures->ranges[0].size = info->fix.smem_len;
  
  	info->fbops = &simplefb_ops;
  	info->flags = FBINFO_DEFAULT | FBINFO_MISC_FIRMWARE;
  	info->screen_base = ioremap_wc(info->fix.smem_start,
  				       info->fix.smem_len);
  	if (!info->screen_base) {
  		framebuffer_release(info);
  		return -ENODEV;
  	}
  	info->pseudo_palette = (void *)(info + 1);
  
  	dev_info(&pdev->dev, "framebuffer at 0x%lx, 0x%x bytes, mapped to 0x%p
  ",
  			     info->fix.smem_start, info->fix.smem_len,
  			     info->screen_base);
  	dev_info(&pdev->dev, "format=%s, mode=%dx%dx%d, linelength=%d
  ",
  			     params.format->name,
  			     info->var.xres, info->var.yres,
  			     info->var.bits_per_pixel, info->fix.line_length);
  
  	ret = register_framebuffer(info);
  	if (ret < 0) {
  		dev_err(&pdev->dev, "Unable to register simplefb: %d
  ", ret);
  		iounmap(info->screen_base);
  		framebuffer_release(info);
  		return ret;
  	}
  
  	dev_info(&pdev->dev, "fb%d: simplefb registered!
  ", info->node);
  
  	return 0;
  }
  
  static int simplefb_remove(struct platform_device *pdev)
  {
  	struct fb_info *info = platform_get_drvdata(pdev);
  
  	unregister_framebuffer(info);
  	framebuffer_release(info);
  
  	return 0;
  }
  
  static const struct of_device_id simplefb_of_match[] = {
  	{ .compatible = "simple-framebuffer", },
  	{ },
  };
  MODULE_DEVICE_TABLE(of, simplefb_of_match);
  
  static struct platform_driver simplefb_driver = {
  	.driver = {
  		.name = "simple-framebuffer",
  		.owner = THIS_MODULE,
  		.of_match_table = simplefb_of_match,
  	},
  	.probe = simplefb_probe,
  	.remove = simplefb_remove,
  };
  module_platform_driver(simplefb_driver);
  
  MODULE_AUTHOR("Stephen Warren <swarren@wwwdotorg.org>");
  MODULE_DESCRIPTION("Simple framebuffer driver");
  MODULE_LICENSE("GPL v2");