drivers/video/simplefb.c

   1 /*
   2  * Simplest possible simple frame-buffer driver, as a platform device
   3  *
   4  * Copyright (c) 2013, Stephen Warren
   5  *
   6  * Based on q40fb.c, which was:
   7  * Copyright (C) 2001 Richard Zidlicky <rz@linux-m68k.org>
   8  *
   9  * Also based on offb.c, which was:
  10  * Copyright (C) 1997 Geert Uytterhoeven
  11  * Copyright (C) 1996 Paul Mackerras
  12  *
  13  * This program is free software; you can redistribute it and/or modify it
  14  * under the terms and conditions of the GNU General Public License,
  15  * version 2, as published by the Free Software Foundation.
  16  *
  17  * This program is distributed in the hope it will be useful, but WITHOUT
  18  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  19  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  20  * more details.
  21  */
  22
  23 #include <linux/errno.h>
  24 #include <linux/fb.h>
  25 #include <linux/io.h>
  26 #include <linux/module.h>
  27 #include <linux/platform_device.h>
  28
  29 static struct fb_fix_screeninfo simplefb_fix = {
  30         .id             = "simple",
  31         .type           = FB_TYPE_PACKED_PIXELS,
  32         .visual         = FB_VISUAL_TRUECOLOR,
  33         .accel          = FB_ACCEL_NONE,
  34 };
  35
  36 static struct fb_var_screeninfo simplefb_var = {
  37         .height         = -1,
  38         .width          = -1,
  39         .activate       = FB_ACTIVATE_NOW,
  40         .vmode          = FB_VMODE_NONINTERLACED,
  41 };
  42
  43 static int simplefb_setcolreg(u_int regno, u_int red, u_int green, u_int blue,
  44                               u_int transp, struct fb_info *info)
  45 {
  46         u32 *pal = info->pseudo_palette;
  47         u32 cr = red >> (16 - info->var.red.length);
  48         u32 cg = green >> (16 - info->var.green.length);
  49         u32 cb = blue >> (16 - info->var.blue.length);
  50         u32 value;
  51
  52         if (regno >= 16)
  53                 return -EINVAL;
  54
  55         value = (cr << info->var.red.offset) |
  56                 (cg << info->var.green.offset) |
  57                 (cb << info->var.blue.offset);
  58         if (info->var.transp.length > 0) {
  59                 u32 mask = (1 << info->var.transp.length) - 1;
  60                 mask <<= info->var.transp.offset;
  61                 value |= mask;
  62         }
  63         pal[regno] = value;
  64
  65         return 0;
  66 }
  67
  68 static struct fb_ops simplefb_ops = {
  69         .owner          = THIS_MODULE,
  70         .fb_setcolreg   = simplefb_setcolreg,
  71         .fb_fillrect    = cfb_fillrect,
  72         .fb_copyarea    = cfb_copyarea,
  73         .fb_imageblit   = cfb_imageblit,
  74 };
  75
  76 struct simplefb_format {
  77         const char *name;
  78         u32 bits_per_pixel;
  79         struct fb_bitfield red;
  80         struct fb_bitfield green;
  81         struct fb_bitfield blue;
  82         struct fb_bitfield transp;
  83 };
  84
  85 static struct simplefb_format simplefb_formats[] = {
  86         { "r5g6b5", 16, {11, 5}, {5, 6}, {0, 5}, {0, 0} },
  87 };
  88
  89 struct simplefb_params {
  90         u32 width;
  91         u32 height;
  92         u32 stride;
  93         struct simplefb_format *format;
  94 };
  95
  96 static int simplefb_parse_dt(struct platform_device *pdev,
  97                            struct simplefb_params *params)
  98 {
  99         struct device_node *np = pdev->dev.of_node;
 100         int ret;
 101         const char *format;
 102         int i;
 103
 104         ret = of_property_read_u32(np, "width", &params->width);
 105         if (ret) {
 106                 dev_err(&pdev->dev, "Can't parse width property\n");
 107                 return ret;
 108         }
 109
 110         ret = of_property_read_u32(np, "height", &params->height);
 111         if (ret) {
 112                 dev_err(&pdev->dev, "Can't parse height property\n");
 113                 return ret;
 114         }
 115
 116         ret = of_property_read_u32(np, "stride", &params->stride);
 117         if (ret) {
 118                 dev_err(&pdev->dev, "Can't parse stride property\n");
 119                 return ret;
 120         }
 121
 122         ret = of_property_read_string(np, "format", &format);
 123         if (ret) {
 124                 dev_err(&pdev->dev, "Can't parse format property\n");
 125                 return ret;
 126         }
 127         params->format = NULL;
 128         for (i = 0; i < ARRAY_SIZE(simplefb_formats); i++) {
 129                 if (strcmp(format, simplefb_formats[i].name))
 130                         continue;
 131                 params->format = &simplefb_formats[i];
 132                 break;
 133         }
 134         if (!params->format) {
 135                 dev_err(&pdev->dev, "Invalid format value\n");
 136                 return -EINVAL;
 137         }
 138
 139         return 0;
 140 }
 141
 142 static int simplefb_probe(struct platform_device *pdev)
 143 {
 144         int ret;
 145         struct simplefb_params params;
 146         struct fb_info *info;
 147         struct resource *mem;
 148
 149         if (fb_get_options("simplefb", NULL))
 150                 return -ENODEV;
 151
 152         ret = simplefb_parse_dt(pdev, &params);
 153         if (ret)
 154                 return ret;
 155
 156         mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 157         if (!mem) {
 158                 dev_err(&pdev->dev, "No memory resource\n");
 159                 return -EINVAL;
 160         }
 161
 162         info = framebuffer_alloc(sizeof(u32) * 16, &pdev->dev);
 163         if (!info)
 164                 return -ENOMEM;
 165         platform_set_drvdata(pdev, info);
 166
 167         info->fix = simplefb_fix;
 168         info->fix.smem_start = mem->start;
 169         info->fix.smem_len = resource_size(mem);
 170         info->fix.line_length = params.stride;
 171
 172         info->var = simplefb_var;
 173         info->var.xres = params.width;
 174         info->var.yres = params.height;
 175         info->var.xres_virtual = params.width;
 176         info->var.yres_virtual = params.height;
 177         info->var.bits_per_pixel = params.format->bits_per_pixel;
 178         info->var.red = params.format->red;
 179         info->var.green = params.format->green;
 180         info->var.blue = params.format->blue;
 181         info->var.transp = params.format->transp;
 182
 183         info->fbops = &simplefb_ops;
 184         info->flags = FBINFO_DEFAULT;
 185         info->screen_base = devm_ioremap(&pdev->dev, info->fix.smem_start,
 186                                          info->fix.smem_len);
 187         if (!info->screen_base) {
 188                 framebuffer_release(info);
 189                 return -ENODEV;
 190         }
 191         info->pseudo_palette = (void *)(info + 1);
 192
 193         ret = register_framebuffer(info);
 194         if (ret < 0) {
 195                 dev_err(&pdev->dev, "Unable to register simplefb: %d\n", ret);
 196                 framebuffer_release(info);
 197                 return ret;
 198         }
 199
 200         dev_info(&pdev->dev, "fb%d: simplefb registered!\n", info->node);
 201
 202         return 0;
 203 }
 204
 205 static int simplefb_remove(struct platform_device *pdev)
 206 {
 207         struct fb_info *info = platform_get_drvdata(pdev);
 208
 209         unregister_framebuffer(info);
 210         framebuffer_release(info);
 211
 212         return 0;
 213 }
 214
 215 static const struct of_device_id simplefb_of_match[] = {
 216         { .compatible = "simple-framebuffer", },
 217         { },
 218 };
 219 MODULE_DEVICE_TABLE(of, simplefb_of_match);
 220
 221 static struct platform_driver simplefb_driver = {
 222         .driver = {
 223                 .name = "simple-framebuffer",
 224                 .owner = THIS_MODULE,
 225                 .of_match_table = simplefb_of_match,
 226         },
 227         .probe = simplefb_probe,
 228         .remove = simplefb_remove,
 229 };
 230 module_platform_driver(simplefb_driver);
 231
 232 MODULE_AUTHOR("Stephen Warren <swarren@wwwdotorg.org>");
 233 MODULE_DESCRIPTION("Simple framebuffer driver");
 234 MODULE_LICENSE("GPL v2");