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authorDavid Herrmann <dh.herrmann@gmail.com>2013-08-02 16:05:22 +0400
committerH. Peter Anvin <hpa@linux.intel.com>2013-08-03 03:17:46 +0400
commite3263ab389a7bc9398c3d366819d6f39b9cfd677 (patch)
treeaa42182804337d3a491f16a5d581e1102a110858 /arch/x86/kernel/sysfb.c
parentdf0960ab2d95543a7c162b04b2064991666adbad (diff)
downloadlinux-e3263ab389a7bc9398c3d366819d6f39b9cfd677.tar.xz
x86: provide platform-devices for boot-framebuffers
The current situation regarding boot-framebuffers (VGA, VESA/VBE, EFI) on x86 causes troubles when loading multiple fbdev drivers. The global "struct screen_info" does not provide any state-tracking about which drivers use the FBs. request_mem_region() theoretically works, but unfortunately vesafb/efifb ignore it due to quirks for broken boards. Avoid this by creating a platform framebuffer devices with a pointer to the "struct screen_info" as platform-data. Drivers can now create platform-drivers and the driver-core will refuse multiple drivers being active simultaneously. We keep the screen_info available for backwards-compatibility. Drivers can be converted in follow-up patches. Different devices are created for VGA/VESA/EFI FBs to allow multiple drivers to be loaded on distro kernels. We create: - "vesa-framebuffer" for VBE/VESA graphics FBs - "efi-framebuffer" for EFI FBs - "platform-framebuffer" for everything else This allows to load vesafb, efifb and others simultaneously and each picks up only the supported FB types. Apart from platform-framebuffer devices, this also introduces a compatibility option for "simple-framebuffer" drivers which recently got introduced for OF based systems. If CONFIG_X86_SYSFB is selected, we try to match the screen_info against a simple-framebuffer supported format. If we succeed, we create a "simple-framebuffer" device instead of a platform-framebuffer. This allows to reuse the simplefb.c driver across architectures and also to introduce a SimpleDRM driver. There is no need to have vesafb.c, efifb.c, simplefb.c and more just to have architecture specific quirks in their setup-routines. Instead, we now move the architecture specific quirks into x86-setup and provide a generic simple-framebuffer. For backwards-compatibility (if strange formats are used), we still allow vesafb/efifb to be loaded simultaneously and pick up all remaining devices. Signed-off-by: David Herrmann <dh.herrmann@gmail.com> Link: http://lkml.kernel.org/r/1375445127-15480-4-git-send-email-dh.herrmann@gmail.com Tested-by: Stephen Warren <swarren@nvidia.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/kernel/sysfb.c')
-rw-r--r--arch/x86/kernel/sysfb.c71
1 files changed, 71 insertions, 0 deletions
diff --git a/arch/x86/kernel/sysfb.c b/arch/x86/kernel/sysfb.c
new file mode 100644
index 000000000000..7f30e194eb52
--- /dev/null
+++ b/arch/x86/kernel/sysfb.c
@@ -0,0 +1,71 @@
+/*
+ * Generic System Framebuffers on x86
+ * Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com>
+ *
+ * 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.
+ */
+
+/*
+ * Simple-Framebuffer support for x86 systems
+ * Create a platform-device for any available boot framebuffer. The
+ * simple-framebuffer platform device is already available on DT systems, so
+ * this module parses the global "screen_info" object and creates a suitable
+ * platform device compatible with the "simple-framebuffer" DT object. If
+ * the framebuffer is incompatible, we instead create a legacy
+ * "vesa-framebuffer", "efi-framebuffer" or "platform-framebuffer" device and
+ * pass the screen_info as platform_data. This allows legacy drivers
+ * to pick these devices up without messing with simple-framebuffer drivers.
+ * The global "screen_info" is still valid at all times.
+ *
+ * If CONFIG_X86_SYSFB is not selected, we never register "simple-framebuffer"
+ * platform devices, but only use legacy framebuffer devices for
+ * backwards compatibility.
+ *
+ * TODO: We set the dev_id field of all platform-devices to 0. This allows
+ * other x86 OF/DT parsers to create such devices, too. However, they must
+ * start at offset 1 for this to work.
+ */
+
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/platform_data/simplefb.h>
+#include <linux/platform_device.h>
+#include <linux/screen_info.h>
+#include <asm/sysfb.h>
+
+static __init int sysfb_init(void)
+{
+ struct screen_info *si = &screen_info;
+ struct simplefb_platform_data mode;
+ struct platform_device *pd;
+ const char *name;
+ bool compatible;
+ int ret;
+
+ /* try to create a simple-framebuffer device */
+ compatible = parse_mode(si, &mode);
+ if (compatible) {
+ ret = create_simplefb(si, &mode);
+ if (!ret)
+ return 0;
+ }
+
+ /* if the FB is incompatible, create a legacy framebuffer device */
+ if (si->orig_video_isVGA == VIDEO_TYPE_EFI)
+ name = "efi-framebuffer";
+ else if (si->orig_video_isVGA == VIDEO_TYPE_VLFB)
+ name = "vesa-framebuffer";
+ else
+ name = "platform-framebuffer";
+
+ pd = platform_device_register_resndata(NULL, name, 0,
+ NULL, 0, si, sizeof(*si));
+ return IS_ERR(pd) ? PTR_ERR(pd) : 0;
+}
+
+device_initcall(sysfb_init);