There are several situations where we want hardware handover from an early
boot GFX driver (e.g., vgacon, vesafb, efifb, simplefb) to a full fletched
GFX driver (e.g., most DRM drivers). So far, we relied on
remove_conflicting_framebuffers() to do this for us, however, this had a
bunch of downsides:
o It only removes conflicting fbdev drivers. It does not drop vgacon,
early boot console drivers, conflicting DRM drivers, etc.
o It only unloads the fbdev driver, it does not modify the underlying
device or resources. In case of "screen_info" drivers (e.g., efifb)
this is fine, since no resources are pinned. However, if the driver
binds to a platform-device like "simple-framebuffer", we must make
sure to unregister that device as well. Otherwise, pinned resources
like IORESOURCE_MEM stay around, triggering WARN_ONs if the following
driver requests those resources.
o It is only available if CONFIG_FB is selected.
This commit adds a new infrastructure that manages system-framebuffers
(short: sysfb). The initial commit provides conflict-resolution for
system-framebuffers. At its core it provides sysfb_evict_conflicts(),
which implements conflict detection and removal for all known types of
GFX driver hand-overs. So far, this includes platform-device removal,
fbdev-firmware-device removal, vgacon removal and VBE detection. To
further simplify the callers, it also provides helpers to figure out what
hand-over to do, based on the device the new drivers binds to:
o PCI drivers can use sysfb_evict_conflicts_pci(), which will figure
out
the apertures automatically, and does VGA/VBE detection.
o Generic firmware drivers that might be shadowed at any address in
memory can use sysfb_evict_conflicts_firmware(), basically removing
*all* firmware framebuffers in effect.
This only adds the generic sysfb helpers. No users are converted, yet.
Signed-off-by: David Herrmann <dh.herrmann@xxxxxxxxx>
---
drivers/video/Kconfig | 4 +
drivers/video/Makefile | 1 +
drivers/video/sysfb.c | 327
+++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/sysfb.h | 34 +++++
4 files changed, 366 insertions(+)
create mode 100644 drivers/video/sysfb.c
create mode 100644 include/linux/sysfb.h
diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index 3c20af9..56a8294 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -36,6 +36,10 @@ config VIDEOMODE_HELPERS
config HDMI
bool
+config SYSFB
+ bool
+ select DUMMY_CONSOLE if VT
+
if VT
source "drivers/video/console/Kconfig"
endif
diff --git a/drivers/video/Makefile b/drivers/video/Makefile
index 9ad3c17..df7bd75 100644
--- a/drivers/video/Makefile
+++ b/drivers/video/Makefile
@@ -1,5 +1,6 @@
obj-$(CONFIG_VGASTATE) += vgastate.o
obj-$(CONFIG_HDMI) += hdmi.o
+obj-$(CONFIG_SYSFB) += sysfb.o
obj-$(CONFIG_VT) += console/
obj-$(CONFIG_LOGO) += logo/
diff --git a/drivers/video/sysfb.c b/drivers/video/sysfb.c
new file mode 100644
index 0000000..00585c9
--- /dev/null
+++ b/drivers/video/sysfb.c
@@ -0,0 +1,327 @@
+/*
+ * Copyright (C) 2013-2016 Red Hat, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
it
+ * under the terms of the GNU Lesser General Public License as published
by the
+ * Free Software Foundation; either version 2.1 of the License, or (at
your
+ * option) any later version.
+ */
+
+#define pr_fmt(fmt) "sysfb: " fmt
+#include <linux/console.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/fb.h>
+#include <linux/ioport.h>
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/pci.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/sysfb.h>
+#include <linux/vt.h>
+
+static bool sysfb_evict_match_resource(struct sysfb_evict_ctx *ctx,
+ struct resource *mem)
+{
+ struct aperture *g;
+ unsigned int i;
+
+ for (i = 0; i < ctx->ap->count; ++i) {
+ g = &ctx->ap->ranges[i];
+
+ if (mem->start == g->base)
+ return true;
+ if (mem->start >= g->base && mem->end < g->base + g->size)
+ return true;
+ if ((ctx->flags & SYSFB_EVICT_VBE) && mem->start ==
0xA0000)
+ return true;
+ }
+
+ return false;
+}
+
+static int sysfb_evict_platform_device(struct device *dev, void
*userdata)
+{
+ struct sysfb_evict_ctx *ctx = userdata;
+ struct platform_device *pdev = to_platform_device(dev);
+ struct resource *mem;
+
+ if (!pdev->name)
+ return 0;
+
+ if (!strcmp(pdev->name, "simple-framebuffer")) {
