[RFC 4/6] drm: simpledrm: add fbdev fallback support
From: David Herrmann
Date: Mon Jun 24 2013 - 18:28:26 EST
Create a simple fbdev device during SimpleDRM setup so legacy user-space
and fbcon can use it.
fbdev deletion is quite buggy. A unregister_framebuffer() call followed by
a printk() causes NULL-derefs in hide_cursor() and other places in the VT
layer. Hence, we leak the fbdev device currently to make the VT layer
happy. This needs to be fixed soon! Otherwise, we need a "depends !VT"
line for SimpleDRM.
Signed-off-by: David Herrmann <dh.herrmann@xxxxxxxxx>
---
drivers/gpu/drm/simpledrm/Kconfig | 11 ++
drivers/gpu/drm/simpledrm/Makefile | 4 +
drivers/gpu/drm/simpledrm/simpledrm.h | 22 ++++
drivers/gpu/drm/simpledrm/simpledrm_fbdev.c | 180 ++++++++++++++++++++++++++++
drivers/gpu/drm/simpledrm/simpledrm_main.c | 2 +
5 files changed, 219 insertions(+)
create mode 100644 drivers/gpu/drm/simpledrm/simpledrm_fbdev.c
diff --git a/drivers/gpu/drm/simpledrm/Kconfig b/drivers/gpu/drm/simpledrm/Kconfig
index 1d4f38e..7936211 100644
--- a/drivers/gpu/drm/simpledrm/Kconfig
+++ b/drivers/gpu/drm/simpledrm/Kconfig
@@ -12,7 +12,18 @@ config DRM_SIMPLEDRM
SimpleDRM supports: "simple-framebuffer" DeviceTree objects, x86 VESA
BIOS Extensions (VBE), EFI framebuffers
+ If fbdev support is enabled, this driver will also provide an fbdev
+ compatibility layer.
+
If unsure, say Y.
To compile this driver as a module, choose M here: the
module will be called simpledrm.
+
+config DRM_SIMPLEDRM_FBDEV
+ bool
+ depends on DRM_SIMPLEDRM && FB
+ default y
+ select FB_CFB_FILLRECT
+ select FB_CFB_COPYAREA
+ select FB_CFB_IMAGEBLIT
diff --git a/drivers/gpu/drm/simpledrm/Makefile b/drivers/gpu/drm/simpledrm/Makefile
index 2d474a5..e77bd9b 100644
--- a/drivers/gpu/drm/simpledrm/Makefile
+++ b/drivers/gpu/drm/simpledrm/Makefile
@@ -2,4 +2,8 @@ ccflags-y := -Iinclude/drm
simpledrm-y := simpledrm_drv.o simpledrm_main.o simpledrm_mem.o
+ifdef CONFIG_DRM_SIMPLEDRM_FBDEV
+ simpledrm-y += simpledrm_fbdev.o
+endif
+
obj-$(CONFIG_DRM_SIMPLEDRM) := simpledrm.o
diff --git a/drivers/gpu/drm/simpledrm/simpledrm.h b/drivers/gpu/drm/simpledrm/simpledrm.h
index 279d847..cfd99f9 100644
--- a/drivers/gpu/drm/simpledrm/simpledrm.h
+++ b/drivers/gpu/drm/simpledrm/simpledrm.h
@@ -48,6 +48,9 @@ struct sdrm_device {
struct drm_encoder enc;
struct drm_connector conn;
struct drm_display_mode *mode;
+
+ /* fbdev */
+ struct fb_info *fbdev;
};
int sdrm_drm_load(struct drm_device *ddev, unsigned long flags);
@@ -88,4 +91,23 @@ struct sdrm_framebuffer {
#define to_sdrm_fb(x) container_of(x, struct sdrm_framebuffer, base)
+/* simpledrm fbdev helpers */
+
+#ifdef CONFIG_DRM_SIMPLEDRM_FBDEV
+
+void sdrm_fbdev_init(struct sdrm_device *sdrm);
+void sdrm_fbdev_cleanup(struct sdrm_device *sdrm);
+
+#else /* CONFIG_DRM_SIMPLEDRM_FBDEV */
+
+static inline void sdrm_fbdev_init(struct sdrm_device *sdrm)
+{
+}
+
+static inline void sdrm_fbdev_cleanup(struct sdrm_device *sdrm)
+{
+}
+
+#endif /* CONFIG_DRM_SIMPLEDRM_FBDEV */
+
#endif /* SDRM_DRV_H */
diff --git a/drivers/gpu/drm/simpledrm/simpledrm_fbdev.c b/drivers/gpu/drm/simpledrm/simpledrm_fbdev.c
new file mode 100644
index 0000000..40a2696
--- /dev/null
+++ b/drivers/gpu/drm/simpledrm/simpledrm_fbdev.c
@@ -0,0 +1,180 @@
+/*
+ * SimpleDRM firmware framebuffer driver
+ * Copyright (c) 2012-2013 David Herrmann <dh.herrmann@xxxxxxxxx>
+ */
+
+/*
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ */
+
+/*
+ * fbdev compatibility layer
+ * We provide a basic fbdev device for the same framebuffer that is used for
+ * the pseudo CRTC.
+ */
+
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/fb.h>
+#include "simpledrm.h"
+
+struct sdrm_fbdev {
+ u32 palette[256];
+};
+
+static int sdrm_fbdev_setcolreg(unsigned regno, unsigned red, unsigned green,
+ unsigned blue, unsigned transp,
+ struct fb_info *info)
+{
+ /*
+ * Set a single color register. The values supplied are
+ * already rounded down to the hardware's capabilities
+ * (according to the entries in the `var' structure). Return != 0 for
+ * invalid regno.
+ */
+
+ if (regno >= info->cmap.len)
+ return 1;
+ if (info->var.bits_per_pixel == 8)
+ return -EINVAL;
+ if (regno >= 16)
+ return 0;
+
+ switch (info->var.bits_per_pixel) {
+ case 16:
+ if (info->var.red.offset == 10) {
+ /* 1:5:5:5 */
+ ((u32*) (info->pseudo_palette))[regno] =
+ ((red & 0xf800) >> 1) |
+ ((green & 0xf800) >> 6) |
+ ((blue & 0xf800) >> 11);
+ } else {
+ /* 0:5:6:5 */
+ ((u32*) (info->pseudo_palette))[regno] =
+ ((red & 0xf800) ) |
+ ((green & 0xfc00) >> 5) |
+ ((blue & 0xf800) >> 11);
+ }
+ break;
+ case 24:
+ case 32:
+ red >>= 8;
+ green >>= 8;
+ blue >>= 8;
+ ((u32*) (info->pseudo_palette))[regno] =
+ (red << info->var.red.offset) |
+ (green << info->var.green.offset) |
+ (blue << info->var.blue.offset);
+ break;
+ }
+
+ return 0;
+}
+
+static struct fb_ops sdrm_fbdev_ops = {
+ .owner = THIS_MODULE,
+ .fb_setcolreg = sdrm_fbdev_setcolreg,
+ .fb_fillrect = cfb_fillrect,
+ .fb_copyarea = cfb_copyarea,
+ .fb_imageblit = cfb_imageblit,
+};
+
+void sdrm_fbdev_init(struct sdrm_device *sdrm)
+{
+ struct sdrm_fbdev *fb;
+ struct fb_info *info;
+ int ret;
+
+ info = framebuffer_alloc(sizeof(struct sdrm_fbdev), sdrm->ddev->dev);
+ if (!info)
+ goto err_out;
+
+ fb = info->par;
+ info->flags = FBINFO_FLAG_DEFAULT | FBINFO_MISC_FIRMWARE;
+ info->pseudo_palette = fb->palette;
+ info->fbops = &sdrm_fbdev_ops;
+ info->screen_base = sdrm->fb_map;
+
+ strncpy(info->fix.id, "simpledrmfb", 15);
+ info->fix.type = FB_TYPE_PACKED_PIXELS;
+ info->fix.visual = FB_VISUAL_TRUECOLOR;
+ info->fix.accel = FB_ACCEL_NONE;
+ info->fix.smem_start = (unsigned long)sdrm->fb_base;
+ info->fix.smem_len = sdrm->fb_size;
+ info->fix.line_length = sdrm->fb_stride;
+
+ info->var.activate = FB_ACTIVATE_NOW;
+ info->var.vmode = FB_VMODE_NONINTERLACED;
+ info->var.bits_per_pixel = sdrm->fb_bpp;
+ info->var.height = -1;
+ info->var.width = -1;
+ info->var.xres = sdrm->fb_width;
+ info->var.yres = sdrm->fb_height;
+ info->var.xres_virtual = info->var.xres;
+ info->var.yres_virtual = info->var.yres;
+ info->var.red = sdrm->fb_sformat->red;
+ info->var.green = sdrm->fb_sformat->green;
+ info->var.blue = sdrm->fb_sformat->blue;
+ info->var.transp = sdrm->fb_sformat->transp;
+
+ /* some dummy values for timing to make fbset happy */
+ info->var.pixclock = 10000000 / info->var.xres * 1000 / info->var.yres;
+ info->var.left_margin = (info->var.xres / 8) & 0xf8;
+ info->var.right_margin = 32;
+ info->var.upper_margin = 16;
+ info->var.lower_margin = 4;
+ info->var.hsync_len = (info->var.xres / 8) & 0xf8;
+ info->var.vsync_len = 4;
+
+ info->apertures = alloc_apertures(1);
+ if (!info->apertures)
+ goto err_free;
+
+ info->apertures->ranges[0].base = (unsigned long)sdrm->fb_base;
+ info->apertures->ranges[0].size = sdrm->fb_size;
+
+ sdrm->fbdev = info;
+ ret = register_framebuffer(info);
+ if (ret < 0)
+ goto err_free;
+
+ dev_info(sdrm->ddev->dev, "fbdev frontend %s as fb%d\n",
+ info->fix.id, info->node);
+
+ return;
+
+err_free:
+ framebuffer_release(info);
+err_out:
+ dev_warn(sdrm->ddev->dev, "cannot create fbdev frontend\n");
+}
+
+void sdrm_fbdev_cleanup(struct sdrm_device *sdrm)
+{
+ struct fb_info *info;
+
+ if (!sdrm->info)
+ return;
+
+ dev_info(sdrm->ddev->dev, "fbdev cleanup\n");
+ info = sdrm->fbdev;
+ sdrm->fbdev = NULL;
+
+ unregister_framebuffer(info);
+
+ /*
+ * FIXME: unregister_framebuffer() may silently fail, which is odd
+ * because there is no sane way for us to detect when to release the
+ * framebuffer.
+ * If we fix unbind_console() to not fail during framebuffer
+ * unregistration, we end up with NULL-derefs in the VT layer
+ * afterwards. So lets just leak the FB here for the VT layer's sake.
+ */
+ /* framebuffer_release(info); */
+}
diff --git a/drivers/gpu/drm/simpledrm/simpledrm_main.c b/drivers/gpu/drm/simpledrm/simpledrm_main.c
index dcc3d0a..ffa1abb 100644
--- a/drivers/gpu/drm/simpledrm/simpledrm_main.c
+++ b/drivers/gpu/drm/simpledrm/simpledrm_main.c
@@ -305,6 +305,7 @@ int sdrm_drm_load(struct drm_device *ddev, unsigned long flags)
if (ret)
goto err_cleanup;
+ sdrm_fbdev_init(sdrm);
return 0;
err_cleanup:
@@ -322,6 +323,7 @@ int sdrm_drm_unload(struct drm_device *ddev)
{
struct sdrm_device *sdrm = ddev->dev_private;
+ sdrm_fbdev_cleanup(sdrm);
drm_mode_config_cleanup(ddev);
sdrm_pdev_destroy(sdrm);
kfree(sdrm);
--
1.8.3.1
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