1 /* 2 * Copyright (C) 2014 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #include <stdbool.h> 18 #include <stdlib.h> 19 #include <string.h> 20 #include <unistd.h> 21 22 #include <fcntl.h> 23 #include <stdio.h> 24 25 #include <sys/cdefs.h> 26 #include <sys/ioctl.h> 27 #include <sys/mman.h> 28 #include <sys/types.h> 29 30 #include <linux/fb.h> 31 #include <linux/kd.h> 32 33 #include "minui.h" 34 #include "graphics.h" 35 36 static GRSurface* fbdev_init(minui_backend*); 37 static GRSurface* fbdev_flip(minui_backend*); 38 static void fbdev_blank(minui_backend*, bool); 39 static void fbdev_exit(minui_backend*); 40 41 static GRSurface gr_framebuffer[2]; 42 static bool double_buffered; 43 static GRSurface* gr_draw = NULL; 44 static int displayed_buffer; 45 46 static fb_var_screeninfo vi; 47 static int fb_fd = -1; 48 49 static minui_backend my_backend = { 50 .init = fbdev_init, 51 .flip = fbdev_flip, 52 .blank = fbdev_blank, 53 .exit = fbdev_exit, 54 }; 55 56 minui_backend* open_fbdev() { 57 return &my_backend; 58 } 59 60 static void fbdev_blank(minui_backend* backend __unused, bool blank) 61 { 62 int ret; 63 64 ret = ioctl(fb_fd, FBIOBLANK, blank ? FB_BLANK_POWERDOWN : FB_BLANK_UNBLANK); 65 if (ret < 0) 66 perror("ioctl(): blank"); 67 } 68 69 static void set_displayed_framebuffer(unsigned n) 70 { 71 if (n > 1 || !double_buffered) return; 72 73 vi.yres_virtual = gr_framebuffer[0].height * 2; 74 vi.yoffset = n * gr_framebuffer[0].height; 75 vi.bits_per_pixel = gr_framebuffer[0].pixel_bytes * 8; 76 if (ioctl(fb_fd, FBIOPUT_VSCREENINFO, &vi) < 0) { 77 perror("active fb swap failed"); 78 } 79 displayed_buffer = n; 80 } 81 82 static GRSurface* fbdev_init(minui_backend* backend) { 83 int fd = open("/dev/graphics/fb0", O_RDWR); 84 if (fd == -1) { 85 perror("cannot open fb0"); 86 return NULL; 87 } 88 89 fb_fix_screeninfo fi; 90 if (ioctl(fd, FBIOGET_FSCREENINFO, &fi) < 0) { 91 perror("failed to get fb0 info"); 92 close(fd); 93 return NULL; 94 } 95 96 if (ioctl(fd, FBIOGET_VSCREENINFO, &vi) < 0) { 97 perror("failed to get fb0 info"); 98 close(fd); 99 return NULL; 100 } 101 102 // We print this out for informational purposes only, but 103 // throughout we assume that the framebuffer device uses an RGBX 104 // pixel format. This is the case for every development device I 105 // have access to. For some of those devices (eg, hammerhead aka 106 // Nexus 5), FBIOGET_VSCREENINFO *reports* that it wants a 107 // different format (XBGR) but actually produces the correct 108 // results on the display when you write RGBX. 109 // 110 // If you have a device that actually *needs* another pixel format 111 // (ie, BGRX, or 565), patches welcome... 112 113 printf("fb0 reports (possibly inaccurate):\n" 114 " vi.bits_per_pixel = %d\n" 115 " vi.red.offset = %3d .length = %3d\n" 116 " vi.green.offset = %3d .length = %3d\n" 117 " vi.blue.offset = %3d .length = %3d\n", 118 vi.bits_per_pixel, 119 vi.red.offset, vi.red.length, 120 vi.green.offset, vi.green.length, 121 vi.blue.offset, vi.blue.length); 122 123 void* bits = mmap(0, fi.smem_len, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); 124 if (bits == MAP_FAILED) { 125 perror("failed to mmap framebuffer"); 126 close(fd); 127 return NULL; 128 } 129 130 memset(bits, 0, fi.smem_len); 131 132 gr_framebuffer[0].width = vi.xres; 133 gr_framebuffer[0].height = vi.yres; 134 gr_framebuffer[0].row_bytes = fi.line_length; 135 gr_framebuffer[0].pixel_bytes = vi.bits_per_pixel / 8; 136 gr_framebuffer[0].data = reinterpret_cast<uint8_t*>(bits); 137 memset(gr_framebuffer[0].data, 0, gr_framebuffer[0].height * gr_framebuffer[0].row_bytes); 138 139 /* check if we can use double buffering */ 140 if (vi.yres * fi.line_length * 2 <= fi.smem_len) { 141 double_buffered = true; 142 143 memcpy(gr_framebuffer+1, gr_framebuffer, sizeof(GRSurface)); 144 gr_framebuffer[1].data = gr_framebuffer[0].data + 145 gr_framebuffer[0].height * gr_framebuffer[0].row_bytes; 146 147 gr_draw = gr_framebuffer+1; 148 149 } else { 150 double_buffered = false; 151 152 // Without double-buffering, we allocate RAM for a buffer to 153 // draw in, and then "flipping" the buffer consists of a 154 // memcpy from the buffer we allocated to the framebuffer. 155 156 gr_draw = (GRSurface*) malloc(sizeof(GRSurface)); 157 memcpy(gr_draw, gr_framebuffer, sizeof(GRSurface)); 158 gr_draw->data = (unsigned char*) malloc(gr_draw->height * gr_draw->row_bytes); 159 if (!gr_draw->data) { 160 perror("failed to allocate in-memory surface"); 161 return NULL; 162 } 163 } 164 165 memset(gr_draw->data, 0, gr_draw->height * gr_draw->row_bytes); 166 fb_fd = fd; 167 set_displayed_framebuffer(0); 168 169 printf("framebuffer: %d (%d x %d)\n", fb_fd, gr_draw->width, gr_draw->height); 170 171 fbdev_blank(backend, true); 172 fbdev_blank(backend, false); 173 174 return gr_draw; 175 } 176 177 static GRSurface* fbdev_flip(minui_backend* backend __unused) { 178 if (double_buffered) { 179 // Change gr_draw to point to the buffer currently displayed, 180 // then flip the driver so we're displaying the other buffer 181 // instead. 182 gr_draw = gr_framebuffer + displayed_buffer; 183 set_displayed_framebuffer(1-displayed_buffer); 184 } else { 185 // Copy from the in-memory surface to the framebuffer. 186 memcpy(gr_framebuffer[0].data, gr_draw->data, 187 gr_draw->height * gr_draw->row_bytes); 188 } 189 return gr_draw; 190 } 191 192 static void fbdev_exit(minui_backend* backend __unused) { 193 close(fb_fd); 194 fb_fd = -1; 195 196 if (!double_buffered && gr_draw) { 197 free(gr_draw->data); 198 free(gr_draw); 199 } 200 gr_draw = NULL; 201 } 202
