On ARM PCI systems, the PCI hierarchy might be reconfigured during
boot and the firmware framebuffer might move as a result of that.
The values in screen_info will then be invalid.
Work around this problem by tracking the framebuffer's initial
location before it get relocated; then fix the screen_info state
between reloaction and creating the firmware framebuffer's device.
This functionality has been lifted from efifb. See the commit message
of commit 55d728a40d36 ("efi/fb: Avoid reconfiguration of BAR that
covers the framebuffer") for more information.
Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
---
drivers/firmware/sysfb.c | 2 +
drivers/video/screen_info_pci.c | 88 +++++++++++++++++++++++++++++++++
include/linux/screen_info.h | 16 ++++++
3 files changed, 106 insertions(+)
diff --git a/drivers/firmware/sysfb.c b/drivers/firmware/sysfb.c
index 48a550bd1a93..5791f9dc47df 100644
--- a/drivers/firmware/sysfb.c
+++ b/drivers/firmware/sysfb.c
@@ -101,6 +101,8 @@ static __init int sysfb_init(void)
bool compatible;
int ret = 0;
+ screen_info_apply_fixups();
+
mutex_lock(&disable_lock);
if (disabled)
goto unlock_mutex;
diff --git a/drivers/video/screen_info_pci.c b/drivers/video/screen_info_pci.c
index 16fe4afa3377..a546681b2d15 100644
--- a/drivers/video/screen_info_pci.c
+++ b/drivers/video/screen_info_pci.c
@@ -1,7 +1,95 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/pci.h>
+#include <linux/printk.h>
#include <linux/screen_info.h>
+#include <linux/string.h>
+
+static struct pci_dev *screen_info_lfb_pdev;
+static size_t screen_info_lfb_bar;
+static resource_size_t screen_info_lfb_offset;
+static struct resource screen_info_lfb_res = DEFINE_RES_MEM(0, 0);
+
+static bool __screen_info_relocation_is_valid(const struct screen_info *si, struct resource *pr)
+{
+ u64 size = __screen_info_lfb_size(si, screen_info_video_type(si));
+
+ if (screen_info_lfb_offset > resource_size(pr))
+ return false;
+ if (size > resource_size(pr))
+ return false;
+ if (resource_size(pr) - size < screen_info_lfb_offset)
+ return false;
+
+ return true;
+}
+
+void screen_info_apply_fixups(void)
+{
+ struct screen_info *si = &screen_info;
+
+ if (screen_info_lfb_pdev) {
+ struct resource *pr = &screen_info_lfb_pdev->resource[screen_info_lfb_bar];
+
+ if (pr->start != screen_info_lfb_res.start) {
+ if (__screen_info_relocation_is_valid(si, pr)) {
+ /*
+ * Only update base if we have an actual
+ * relocation to a valid I/O range.
+ */
+ __screen_info_set_lfb_base(si, pr->start + screen_info_lfb_offset);
+ pr_info("Relocating firmware framebuffer to offset %pa[d] within %pr\n",
+ &screen_info_lfb_offset, pr);
+ } else {
+ pr_warn("Invalid relocating, disabling firmware framebuffer\n");
+ }
+ }
+ }
+}
+
+static void screen_info_fixup_lfb(struct pci_dev *pdev)
+{
+ unsigned int type;
+ struct resource res[SCREEN_INFO_MAX_RESOURCES];
+ size_t i, numres;
+ int ret;
+ const struct screen_info *si = &screen_info;
+
+ if (screen_info_lfb_pdev)
+ return; // already found
+
+ type = screen_info_video_type(si);
+ if (type != VIDEO_TYPE_EFI)
+ return; // only applies to EFI
+
+ ret = screen_info_resources(si, res, ARRAY_SIZE(res));
+ if (ret < 0)
+ return;
+ numres = ret;
+
+ for (i = 0; i < numres; ++i) {
+ struct resource *r = &res[i];
+ const struct resource *pr;
+
+ if (!(r->flags & IORESOURCE_MEM))
+ continue;
+ pr = pci_find_resource(pdev, r);
+ if (!pr)
+ continue;
+
+ /*
+ * We've found a PCI device with the framebuffer
+ * resource. Store away the parameters to track
+ * relocation of the framebuffer aperture.
+ */
+ screen_info_lfb_pdev = pdev;
+ screen_info_lfb_bar = pr - pdev->resource;
+ screen_info_lfb_offset = r->start - pr->start;
+ memcpy(&screen_info_lfb_res, r, sizeof(screen_info_lfb_res));
+ }
+}
+DECLARE_PCI_FIXUP_CLASS_HEADER(PCI_ANY_ID, PCI_ANY_ID, PCI_BASE_CLASS_DISPLAY, 16,
+ screen_info_fixup_lfb);
static struct pci_dev *__screen_info_pci_dev(struct resource *res)
{
diff --git a/include/linux/screen_info.h b/include/linux/screen_info.h
index 746645b8ee83..80b348137492 100644
--- a/include/linux/screen_info.h
+++ b/include/linux/screen_info.h
@@ -4,6 +4,8 @@
#include <uapi/linux/screen_info.h>
+#include <linux/bits.h>
+
/**
* SCREEN_INFO_MAX_RESOURCES - maximum number of resources per screen_info
*/
@@ -27,6 +29,17 @@ static inline u64 __screen_info_lfb_base(const struct screen_info *si)
return lfb_base;
}
+static inline void __screen_info_set_lfb_base(struct screen_info *si, u64 lfb_base)
+{
+ si->lfb_base = lfb_base & GENMASK_ULL(31, 0);
+ si->ext_lfb_base = (lfb_base & GENMASK_ULL(63, 32)) >> 32;
+
+ if (si->ext_lfb_base)
+ si->capabilities |= VIDEO_CAPABILITY_64BIT_BASE;
+ else
+ si->capabilities &= ~VIDEO_CAPABILITY_64BIT_BASE;
+}
+
static inline u64 __screen_info_lfb_size(const struct screen_info *si, unsigned int type)
{
u64 lfb_size = si->lfb_size;
@@ -106,8 +119,11 @@ static inline unsigned int screen_info_video_type(const struct screen_info *si)
int screen_info_resources(const struct screen_info *si, struct resource *r, size_t num);
#if defined(CONFIG_PCI)
+void screen_info_apply_fixups(void);
struct pci_dev *screen_info_pci_dev(const struct screen_info *si);
#else
+static inline void screen_info_apply_fixups(void)
+{ }
static inline struct pci_dev *screen_info_pci_dev(const struct screen_info *si)
{
return NULL;
--
2.43.0
