firmware: coreboot: Add coreboot framebuffer driver

Register a simplefb framebuffer when the coreboot table contains a
framebuffer entry.
Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/firmware/google/Kconfig

@@ -55,6 +55,14 @@ config GOOGLE_MEMCONSOLE_X86_LEGACY
 	  the EBDA on Google servers.  If found, this log is exported to
 	  userland in the file /sys/firmware/log.
 
+config GOOGLE_FRAMEBUFFER_COREBOOT
+	tristate "Coreboot Framebuffer"
+	depends on FB_SIMPLE
+	depends on GOOGLE_COREBOOT_TABLE
+	help
+	  This option enables the kernel to search for a framebuffer in
+	  the coreboot table.  If found, it is registered with simplefb.
+
 config GOOGLE_MEMCONSOLE_COREBOOT
 	tristate "Firmware Memory Console"
 	depends on GOOGLE_COREBOOT_TABLE

drivers/firmware/google/Makefile

@@ -4,6 +4,7 @@ obj-$(CONFIG_GOOGLE_SMI)		+= gsmi.o
 obj-$(CONFIG_GOOGLE_COREBOOT_TABLE)        += coreboot_table.o
 obj-$(CONFIG_GOOGLE_COREBOOT_TABLE_ACPI)   += coreboot_table-acpi.o
 obj-$(CONFIG_GOOGLE_COREBOOT_TABLE_OF)     += coreboot_table-of.o
+obj-$(CONFIG_GOOGLE_FRAMEBUFFER_COREBOOT)  += framebuffer-coreboot.o
 obj-$(CONFIG_GOOGLE_MEMCONSOLE)            += memconsole.o
 obj-$(CONFIG_GOOGLE_MEMCONSOLE_COREBOOT)   += memconsole-coreboot.o
 obj-$(CONFIG_GOOGLE_MEMCONSOLE_X86_LEGACY) += memconsole-x86-legacy.o

drivers/firmware/google/coreboot_table.h

@@ -3,6 +3,7 @@
  *
  * Internal header for coreboot table access.
  *
+ * Copyright 2014 Gerd Hoffmann <kraxel@redhat.com>
  * Copyright 2017 Google Inc.
  * Copyright 2017 Samuel Holland <samuel@sholland.org>
  *
@@ -46,12 +47,33 @@ struct lb_cbmem_ref {
 	u64 cbmem_addr;
 };
 
+/* Describes framebuffer setup by coreboot */
+struct lb_framebuffer {
+	u32 tag;
+	u32 size;
+
+	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;
+};
+
 /* A device, additionally with information from coreboot. */
 struct coreboot_device {
 	struct device dev;
 	union {
 		struct coreboot_table_entry entry;
 		struct lb_cbmem_ref cbmem_ref;
+		struct lb_framebuffer framebuffer;
 	};
 };
 

drivers/firmware/google/framebuffer-coreboot.c

+/*
+ * framebuffer-coreboot.c
+ *
+ * Memory based framebuffer accessed through coreboot table.
+ *
+ * Copyright 2012-2013 David Herrmann <dh.herrmann@gmail.com>
+ * Copyright 2017 Google Inc.
+ * Copyright 2017 Samuel Holland <samuel@sholland.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License v2.0 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/platform_data/simplefb.h>
+#include <linux/platform_device.h>
+
+#include "coreboot_table.h"
+
+#define CB_TAG_FRAMEBUFFER 0x12
+
+static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;
+
+static int framebuffer_probe(struct coreboot_device *dev)
+{
+	int i;
+	u32 length;
+	struct lb_framebuffer *fb = &dev->framebuffer;
+	struct platform_device *pdev;
+	struct resource res;
+	struct simplefb_platform_data pdata = {
+		.width = fb->x_resolution,
+		.height = fb->y_resolution,
+		.stride = fb->bytes_per_line,
+		.format = NULL,
+	};
+
+	for (i = 0; i < ARRAY_SIZE(formats); ++i) {
+		if (fb->bits_per_pixel     == formats[i].bits_per_pixel &&
+		    fb->red_mask_pos       == formats[i].red.offset &&
+		    fb->red_mask_size      == formats[i].red.length &&
+		    fb->green_mask_pos     == formats[i].green.offset &&
+		    fb->green_mask_size    == formats[i].green.length &&
+		    fb->blue_mask_pos      == formats[i].blue.offset &&
+		    fb->blue_mask_size     == formats[i].blue.length &&
+		    fb->reserved_mask_pos  == formats[i].transp.offset &&
+		    fb->reserved_mask_size == formats[i].transp.length)
+			pdata.format = formats[i].name;
+	}
+	if (!pdata.format)
+		return -ENODEV;
+
+	memset(&res, 0, sizeof(res));
+	res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+	res.name = "Coreboot Framebuffer";
+	res.start = fb->physical_address;
+	length = PAGE_ALIGN(fb->y_resolution * fb->bytes_per_line);
+	res.end = res.start + length - 1;
+	if (res.end <= res.start)
+		return -EINVAL;
+
+	pdev = platform_device_register_resndata(&dev->dev,
+						 "simple-framebuffer", 0,
+						 &res, 1, &pdata,
+						 sizeof(pdata));
+	if (IS_ERR(pdev))
+		pr_warn("coreboot: could not register framebuffer\n");
+	else
+		dev_set_drvdata(&dev->dev, pdev);
+
+	return PTR_ERR_OR_ZERO(pdev);
+}
+
+static int framebuffer_remove(struct coreboot_device *dev)
+{
+	struct platform_device *pdev = dev_get_drvdata(&dev->dev);
+
+	platform_device_unregister(pdev);
+
+	return 0;
+}
+
+static struct coreboot_driver framebuffer_driver = {
+	.probe = framebuffer_probe,
+	.remove = framebuffer_remove,
+	.drv = {
+		.name = "framebuffer",
+	},
+	.tag = CB_TAG_FRAMEBUFFER,
+};
+
+static int __init coreboot_framebuffer_init(void)
+{
+	return coreboot_driver_register(&framebuffer_driver);
+}
+
+static void coreboot_framebuffer_exit(void)
+{
+	coreboot_driver_unregister(&framebuffer_driver);
+}
+
+module_init(coreboot_framebuffer_init);
+module_exit(coreboot_framebuffer_exit);
+
+MODULE_AUTHOR("Samuel Holland <samuel@sholland.org>");
+MODULE_LICENSE("GPL");