1 files changed, 43 insertions, 5 deletions

diff --git a/drivers/firmware/efi/earlycon.c b/drivers/firmware/efi/earlycon.c
index c9a0efca17b0..5d4f84781aa0 100644
--- a/drivers/firmware/efi/earlycon.c
+++ b/drivers/firmware/efi/earlycon.c
@@ -13,18 +13,58 @@
 
 #include <asm/early_ioremap.h>
 
+static const struct console *earlycon_console __initdata;
 static const struct font_desc *font;
 static u32 efi_x, efi_y;
 static u64 fb_base;
-static pgprot_t fb_prot;
+static bool fb_wb;
+static void *efi_fb;
+
+/*
+ * EFI earlycon needs to use early_memremap() to map the framebuffer.
+ * But early_memremap() is not usable for 'earlycon=efifb keep_bootcon',
+ * memremap() should be used instead. memremap() will be available after
+ * paging_init() which is earlier than initcall callbacks. Thus adding this
+ * early initcall function early_efi_map_fb() to map the whole EFI framebuffer.
+ */
+static int __init efi_earlycon_remap_fb(void)
+{
+	/* bail if there is no bootconsole or it has been disabled already */
+	if (!earlycon_console || !(earlycon_console->flags & CON_ENABLED))
+		return 0;
+
+	efi_fb = memremap(fb_base, screen_info.lfb_size,
+			  fb_wb ? MEMREMAP_WB : MEMREMAP_WC);
+
+	return efi_fb ? 0 : -ENOMEM;
+}
+early_initcall(efi_earlycon_remap_fb);
+
+static int __init efi_earlycon_unmap_fb(void)
+{
+	/* unmap the bootconsole fb unless keep_bootcon has left it enabled */
+	if (efi_fb && !(earlycon_console->flags & CON_ENABLED))
+		memunmap(efi_fb);
+	return 0;
+}
+late_initcall(efi_earlycon_unmap_fb);
 
 static __ref void *efi_earlycon_map(unsigned long start, unsigned long len)
 {
+	pgprot_t fb_prot;
+
+	if (efi_fb)
+		return efi_fb + start;
+
+	fb_prot = fb_wb ? PAGE_KERNEL : pgprot_writecombine(PAGE_KERNEL);
 	return early_memremap_prot(fb_base + start, len, pgprot_val(fb_prot));
 }
 
 static __ref void efi_earlycon_unmap(void *addr, unsigned long len)
 {
+	if (efi_fb)
+		return;
+
 	early_memunmap(addr, len);
 }
 
@@ -176,10 +216,7 @@ static int __init efi_earlycon_setup(struct earlycon_device *device,
 	if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
 		fb_base |= (u64)screen_info.ext_lfb_base << 32;
 
-	if (opt && !strcmp(opt, "ram"))
-		fb_prot = PAGE_KERNEL;
-	else
-		fb_prot = pgprot_writecombine(PAGE_KERNEL);
+	fb_wb = opt && !strcmp(opt, "ram");
 
 	si = &screen_info;
 	xres = si->lfb_width;
@@ -201,6 +238,7 @@ static int __init efi_earlycon_setup(struct earlycon_device *device,
 		efi_earlycon_scroll_up();
 
 	device->con->write = efi_earlycon_write;
+	earlycon_console = device->con;
 	return 0;
 }
 EARLYCON_DECLARE(efifb, efi_earlycon_setup);