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Message-Id: <1409826307-23075-1-git-send-email-kraxel@redhat.com>
Date: Thu, 4 Sep 2014 12:25:07 +0200
From: Gerd Hoffmann <kraxel@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: coreboot@...eboot.org, Gerd Hoffmann <kraxel@...hat.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>,
x86@...nel.org (maintainer:X86 ARCHITECTURE...)
Subject: [PATCH] x86: add coreboot framebuffer support
Signed-off-by: Gerd Hoffmann <kraxel@...hat.com>
---
arch/x86/Kconfig | 12 +++
arch/x86/kernel/Makefile | 1 +
arch/x86/kernel/coreboot.c | 232 +++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 245 insertions(+)
create mode 100644 arch/x86/kernel/coreboot.c
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 778178f..3aeb038 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2372,6 +2372,18 @@ config X86_SYSFB
If unsure, say Y.
+config COREBOOT
+ bool "coreboot"
+ depends on X86_SYSFB
+ depends on FB_SIMPLE
+ help
+ Add coreboot framebuffer support to the linux kernel. Say Y here
+ if you want the linux kernel find and use the firmware framebuffer
+ initialized by coreboot. Useful when using the linux kernel as
+ coreboot payload.
+
+ If unsure, or if you don't know what coreboot is, say N.
+
endmenu
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index ada2e2d..4b30b0e 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -103,6 +103,7 @@ obj-$(CONFIG_UPROBES) += uprobes.o
obj-y += sysfb.o
obj-$(CONFIG_X86_SYSFB) += sysfb_simplefb.o
obj-$(CONFIG_EFI) += sysfb_efi.o
+obj-$(CONFIG_COREBOOT) += coreboot.o
obj-$(CONFIG_PERF_EVENTS) += perf_regs.o
obj-$(CONFIG_TRACING) += tracepoint.o
diff --git a/arch/x86/kernel/coreboot.c b/arch/x86/kernel/coreboot.c
new file mode 100644
index 0000000..44ed3fa
--- /dev/null
+++ b/arch/x86/kernel/coreboot.c
@@ -0,0 +1,232 @@
+/*
+ * Find and parse coreboot tables. Register framebuffer if present.
+ * See src/include/boot/coreboot_tables.h in coreboot source tree.
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+#include <linux/screen_info.h>
+#include <linux/platform_device.h>
+#include <linux/platform_data/simplefb.h>
+#include <video/vga.h>
+
+#include <asm/checksum.h>
+#include <asm/io.h>
+#include <asm/sysfb.h>
+
+struct cb_header {
+ u32 signature;
+ u32 header_bytes;
+ u32 header_checksum;
+ u32 table_bytes;
+ u32 table_checksum;
+ u32 table_entries;
+};
+
+#define CB_TAG_MAINBOARD 0x0003
+#define CB_TAG_VERSION 0x0004
+#define CB_TAG_FORWARD 0x0011
+#define CB_TAG_FRAMEBUFFER 0x0012
+
+struct cb_mainboard {
+ u8 vendor_idx;
+ u8 part_idx;
+ char strings[0];
+};
+
+struct cb_framebuffer {
+ u64 physical_address;
+ u32 x_resolution;
+ u32 y_resolution;
+ u32 bytes_per_line;
+ u8 bits_per_pixel;
+ u8 red_mask_pos;
+ u8 red_mask_size;
+ u8 green_mask_pos;
+ u8 green_mask_size;
+ u8 blue_mask_pos;
+ u8 blue_mask_size;
+ u8 reserved_mask_pos;
+ u8 reserved_mask_size;
+};
+
+struct cb_entry {
+ u32 tag;
+ u32 size;
+ union {
+ char string[0];
+ u64 forward;
+ struct cb_mainboard mb;
+ struct cb_framebuffer fb;
+ } u;
+};
+
+#define CB_SIGNATURE 0x4f49424C /* "LBIO" */
+
+/* Try to locate the coreboot header in a given address range. */
+static __init struct cb_header *coreboot_find_header(u32 addr, int len)
+{
+ struct cb_header *cbh, *copy;
+ int offset;
+ void *map;
+
+ map = ioremap(addr, len);
+ for (offset = 0; offset < len; offset += 16) {
+ cbh = map + offset;
+ if (!cbh)
+ continue;
+ if (cbh->signature != CB_SIGNATURE)
+ continue;
+ if (!cbh->table_bytes)
+ continue;
+ if (ip_compute_csum(cbh, sizeof(*cbh)) != 0)
+ continue;
+ if (ip_compute_csum(cbh + 1, cbh->table_bytes)
+ != cbh->table_checksum)
+ continue;
+ pr_debug("coreboot: header found at 0x%x\n",
+ addr + offset);
+ copy = kzalloc(sizeof(*cbh) + cbh->table_bytes, GFP_KERNEL);
+ memcpy(copy, cbh, sizeof(*cbh) + cbh->table_bytes);
+ iounmap(map);
+ return copy;
+ }
+ iounmap(map);
+ return NULL;
+}
+
+static __init bool check_vga_text_mode(void)
+{
+ uint8_t reg;
+
+ if (screen_info.orig_video_isVGA != 1)
+ return false;
+
+ reg = inb(VGA_GFX_I);
+ if (reg == 0xff)
+ /* no vga present */
+ return false;
+
+ outb(VGA_GFX_MISC, VGA_GFX_I);
+ reg = inb(VGA_GFX_D);
+ if (reg & 0x01)
+ /* vga is in gfx mode */
+ return false;
+
+ return true;
+}
+
+static __init void coreboot_fb_init(struct cb_framebuffer *fb)
+{
+ const char *reason = "";
+ struct simplefb_platform_data mode;
+ struct screen_info si;
+ struct resource res;
+
+ pr_info("coreboot: framebuffer: %dx%d, %d bpp, at %llx\n",
+ fb->x_resolution,
+ fb->y_resolution,
+ fb->bits_per_pixel,
+ fb->physical_address);
+
+ if (screen_info.orig_video_isVGA == VIDEO_TYPE_VLFB) {
+ reason = "have vesa lfb";
+ goto skip;
+ }
+ if (screen_info.orig_video_isVGA == VIDEO_TYPE_EFI) {
+ reason = "have efi gop";
+ goto skip;
+ }
+ if (check_vga_text_mode()) {
+ reason = "vga is in text mode";
+ goto skip;
+ }
+
+ memset(&si, 0, sizeof(si));
+ si.orig_video_isVGA = VIDEO_TYPE_VLFB;
+ si.lfb_width = fb->x_resolution;
+ si.lfb_height = fb->y_resolution;
+ si.lfb_depth = fb->bits_per_pixel;
+ si.lfb_base = fb->physical_address;
+ si.lfb_linelength = fb->bytes_per_line;
+ si.lfb_size =
+ (fb->y_resolution * fb->bytes_per_line + 65535) / 65536;
+ si.pages = 1;
+ si.red_size = fb->red_mask_size;
+ si.red_pos = fb->red_mask_pos;
+ si.green_size = fb->green_mask_size;
+ si.green_pos = fb->green_mask_pos;
+ si.blue_size = fb->blue_mask_size;
+ si.blue_pos = fb->blue_mask_pos;
+ si.rsvd_size = fb->reserved_mask_size;
+ si.rsvd_pos = fb->reserved_mask_pos;
+ if (!parse_mode(&si, &mode)) {
+ reason = "mode not compatible";
+ goto skip;
+ }
+
+ memset(&res, 0, sizeof(res));
+ res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+ res.name = "coreboot-fb";
+ res.start = si.lfb_base;
+ res.end = si.lfb_base + si.lfb_size * 65536 - 1;
+
+ pr_info("coreboot: setting up simplefb\n");
+ platform_device_register_resndata(NULL, "simple-framebuffer", 0,
+ &res, 1, &mode, sizeof(mode));
+ return;
+
+skip:
+ pr_info("coreboot: skipping framebuffer setup (%s)\n", reason);
+ return;
+}
+
+static __init int coreboot_detect(void)
+{
+ struct cb_header *cbh;
+ struct cb_entry *cbe;
+ u64 addr = 0;
+ void *next;
+ int i;
+
+newheader:
+ cbh = coreboot_find_header(addr, 0x1000);
+ if (!cbh)
+ return 0;
+
+ next = cbh + 1;
+ for (i = 0; i < cbh->table_entries; i++) {
+ cbe = next;
+ next += cbe->size;
+ switch (cbe->tag) {
+ case CB_TAG_MAINBOARD:
+ pr_info("coreboot: mainboard: %s / %s\n",
+ cbe->u.mb.strings + cbe->u.mb.vendor_idx,
+ cbe->u.mb.strings + cbe->u.mb.part_idx);
+ break;
+ case CB_TAG_VERSION:
+ pr_info("coreboot: version: %s\n",
+ cbe->u.string);
+ break;
+ case CB_TAG_FORWARD:
+ pr_debug("coreboot: forward to 0x%llx\n",
+ cbe->u.forward);
+ addr = cbe->u.forward;
+ kfree(cbh);
+ goto newheader;
+ case CB_TAG_FRAMEBUFFER:
+ coreboot_fb_init(&cbe->u.fb);
+ break;
+ default:
+ pr_debug("%s: unhandled tag 0x%x (size %d)\n",
+ __func__, cbe->tag, cbe->size);
+ break;
+ }
+ }
+
+ kfree(cbh);
+ return 0;
+}
+
+device_initcall(coreboot_detect);
--
1.8.3.1
--
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