separate fbdev-specific code out from minui

Isolate the code that interacts with fbdev, in preparation for adding
a new backend.

Change-Id: I19105e9da1ca6408cebc110f7e2bb5abfb481ee9

1 files changed, 201 insertions, 0 deletions

diff --git a/minui/graphics_fbdev.c b/minui/graphics_fbdev.c
new file mode 100644
index 00000000..6a6330b2
--- /dev/null
+++ b/minui/graphics_fbdev.c
@@ -0,0 +1,201 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdbool.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <fcntl.h>
+#include <stdio.h>
+
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+
+#include <linux/fb.h>
+#include <linux/kd.h>
+
+#include "minui.h"
+#include "graphics.h"
+
+static gr_surface fbdev_init(minui_backend*);
+static gr_surface fbdev_flip(minui_backend*);
+static void fbdev_blank(minui_backend*, bool);
+static void fbdev_exit(minui_backend*);
+
+static GRSurface gr_framebuffer[2];
+static bool double_buffered;
+static GRSurface* gr_draw = NULL;
+static int displayed_buffer;
+
+static struct fb_var_screeninfo vi;
+static int fb_fd = -1;
+
+static minui_backend my_backend = {
+    .init = fbdev_init,
+    .flip = fbdev_flip,
+    .blank = fbdev_blank,
+    .exit = fbdev_exit,
+};
+
+minui_backend* open_fbdev() {
+    return &my_backend;
+}
+
+static void fbdev_blank(minui_backend* backend, bool blank)
+{
+    int ret;
+
+    ret = ioctl(fb_fd, FBIOBLANK, blank ? FB_BLANK_POWERDOWN : FB_BLANK_UNBLANK);
+    if (ret < 0)
+        perror("ioctl(): blank");
+}
+
+static void set_displayed_framebuffer(unsigned n)
+{
+    if (n > 1 || !double_buffered) return;
+
+    vi.yres_virtual = gr_framebuffer[0].height * 2;
+    vi.yoffset = n * gr_framebuffer[0].height;
+    vi.bits_per_pixel = gr_framebuffer[0].pixel_bytes * 8;
+    if (ioctl(fb_fd, FBIOPUT_VSCREENINFO, &vi) < 0) {
+        perror("active fb swap failed");
+    }
+    displayed_buffer = n;
+}
+
+static gr_surface fbdev_init(minui_backend* backend) {
+    int fd;
+    void *bits;
+
+    struct fb_fix_screeninfo fi;
+
+    fd = open("/dev/graphics/fb0", O_RDWR);
+    if (fd < 0) {
+        perror("cannot open fb0");
+        return NULL;
+    }
+
+    if (ioctl(fd, FBIOGET_FSCREENINFO, &fi) < 0) {
+        perror("failed to get fb0 info");
+        close(fd);
+        return NULL;
+    }
+
+    if (ioctl(fd, FBIOGET_VSCREENINFO, &vi) < 0) {
+        perror("failed to get fb0 info");
+        close(fd);
+        return NULL;
+    }
+
+    // We print this out for informational purposes only, but
+    // throughout we assume that the framebuffer device uses an RGBX
+    // pixel format.  This is the case for every development device I
+    // have access to.  For some of those devices (eg, hammerhead aka
+    // Nexus 5), FBIOGET_VSCREENINFO *reports* that it wants a
+    // different format (XBGR) but actually produces the correct
+    // results on the display when you write RGBX.
+    //
+    // If you have a device that actually *needs* another pixel format
+    // (ie, BGRX, or 565), patches welcome...
+
+    printf("fb0 reports (possibly inaccurate):\n"
+           "  vi.bits_per_pixel = %d\n"
+           "  vi.red.offset   = %3d   .length = %3d\n"
+           "  vi.green.offset = %3d   .length = %3d\n"
+           "  vi.blue.offset  = %3d   .length = %3d\n",
+           vi.bits_per_pixel,
+           vi.red.offset, vi.red.length,
+           vi.green.offset, vi.green.length,
+           vi.blue.offset, vi.blue.length);
+
+    bits = mmap(0, fi.smem_len, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+    if (bits == MAP_FAILED) {
+        perror("failed to mmap framebuffer");
+        close(fd);
+        return NULL;
+    }
+
+    gr_framebuffer[0].width = vi.xres;
+    gr_framebuffer[0].height = vi.yres;
+    gr_framebuffer[0].row_bytes = fi.line_length;
+    gr_framebuffer[0].pixel_bytes = vi.bits_per_pixel / 8;
+    gr_framebuffer[0].data = bits;
+    memset(gr_framebuffer[0].data, 0, gr_framebuffer[0].height * gr_framebuffer[0].row_bytes);
+
+    /* check if we can use double buffering */
+    if (vi.yres * fi.line_length * 2 <= fi.smem_len) {
+        double_buffered = true;
+
+        memcpy(gr_framebuffer+1, gr_framebuffer, sizeof(GRSurface));
+        gr_framebuffer[1].data = gr_framebuffer[0].data +
+            gr_framebuffer[0].height * gr_framebuffer[0].row_bytes;
+
+        gr_draw = gr_framebuffer+1;
+
+    } else {
+        double_buffered = false;
+
+        // Without double-buffering, we allocate RAM for a buffer to
+        // draw in, and then "flipping" the buffer consists of a
+        // memcpy from the buffer we allocated to the framebuffer.
+
+        gr_draw = (GRSurface*) malloc(sizeof(GRSurface));
+        memcpy(gr_draw, gr_framebuffer, sizeof(GRSurface));
+        gr_draw->data = (unsigned char*) malloc(gr_draw->height * gr_draw->row_bytes);
+        if (!gr_draw->data) {
+            perror("failed to allocate in-memory surface");
+            return NULL;
+        }
+    }
+
+    memset(gr_draw->data, 0, gr_draw->height * gr_draw->row_bytes);
+    fb_fd = fd;
+    set_displayed_framebuffer(0);
+
+    printf("framebuffer: %d (%d x %d)\n", fb_fd, gr_draw->width, gr_draw->height);
+
+    fbdev_blank(backend, true);
+    fbdev_blank(backend, false);
+
+    return gr_draw;
+}
+
+static gr_surface fbdev_flip(minui_backend* backend) {
+    if (double_buffered) {
+        // Change gr_draw to point to the buffer currently displayed,
+        // then flip the driver so we're displaying the other buffer
+        // instead.
+        gr_draw = gr_framebuffer + displayed_buffer;
+        set_displayed_framebuffer(1-displayed_buffer);
+    } else {
+        // Copy from the in-memory surface to the framebuffer.
+        memcpy(gr_framebuffer[0].data, gr_draw->data,
+               gr_draw->height * gr_draw->row_bytes);
+    }
+    return gr_draw;
+}
+
+static void fbdev_exit(minui_backend* backend) {
+    close(fb_fd);
+    fb_fd = -1;
+
+    if (!double_buffered && gr_draw) {
+        free(gr_draw->data);
+        free(gr_draw);
+    }
+    gr_draw = NULL;
+}