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Subject[PATCH 02/11] x86: Add device tree support
Date
This patch adds minimal support for device tree support on x86. It will
be passed to the kernel via setup_data which requires atleast boot
protocol 2.09.
Memory size, restricted memory regions, boot arguments are gathered the
traditional way so things like cmd_line are just here to let the code
compile.
The current plan is use the device tree as an extension and to gather
informations from it which can not be enumerated and have to be
hardcoded otherwise. This includes things like
- which devices are on this I2C/ SPI bus?
- how are the interrupts wired to IO APIC?
- where could my hpet be?

Dirk is working on some patches which provide generic infrastructure for
linking the dtb into the kernel. Once this is it its final shape, we
will relocate the device tree unconditionally. This will remove the
requirement for the boot loader to locate the device tree within lowmem.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
CC: x86@kernel.org
Cc: devicetree-discuss@lists.ozlabs.org
Signed-off-by: Dirk Brandewie <dirk.brandewie@gmail.com>
---
Documentation/x86/boot_with_dtb.txt | 20 +++++++++++
arch/x86/Kconfig | 7 ++++
arch/x86/include/asm/bootparam.h | 1 +
arch/x86/include/asm/prom.h | 60 +++++++++++++++++++++++++++++++++++
arch/x86/kernel/Makefile | 1 +
arch/x86/kernel/irqinit.c | 7 ++++
arch/x86/kernel/prom.c | 60 +++++++++++++++++++++++++++++++++++
arch/x86/kernel/setup.c | 4 ++
8 files changed, 160 insertions(+), 0 deletions(-)
create mode 100644 Documentation/x86/boot_with_dtb.txt
create mode 100644 arch/x86/include/asm/prom.h
create mode 100644 arch/x86/kernel/prom.c

diff --git a/Documentation/x86/boot_with_dtb.txt b/Documentation/x86/boot_with_dtb.txt
new file mode 100644
index 0000000..3ba42b4
--- /dev/null
+++ b/Documentation/x86/boot_with_dtb.txt
@@ -0,0 +1,20 @@
+ Booting x86 with device tree
+=================================
+
+1. Introduction
+~~~~~~~~~~~~~~~
+This document contains device tree informations which are specific to
+the x86 platform. Generic informations as bindings can be found in
+Documentation/powerpc/dts-bindings/
+
+2. Passing the device tree
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+The pointer to the device tree block (dtb) is passed via setup_data
+(see [0]) which requires atleast boot protocol 2.09. The type filed is
+defined as
+
+#define SETUP_DTB 2
+
+The setup_data struct has to be placed in lowmem.
+
+[0] Documentation/x86/boot.txt
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 6ab6310..6c9ab9e 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -299,6 +299,13 @@ config X86_BIGSMP
---help---
This option is needed for the systems that have more than 8 CPUs

+config X86_OF
+ bool "Support for device tree"
+ select OF
+ select OF_FLATTREE
+ ---help---
+ Device tree support on X86.
+
if X86_32
config X86_EXTENDED_PLATFORM
bool "Support for extended (non-PC) x86 platforms"
diff --git a/arch/x86/include/asm/bootparam.h b/arch/x86/include/asm/bootparam.h
index c8bfe63..e020d88 100644
--- a/arch/x86/include/asm/bootparam.h
+++ b/arch/x86/include/asm/bootparam.h
@@ -12,6 +12,7 @@
/* setup data types */
#define SETUP_NONE 0
#define SETUP_E820_EXT 1
+#define SETUP_DTB 2

/* extensible setup data list node */
struct setup_data {
diff --git a/arch/x86/include/asm/prom.h b/arch/x86/include/asm/prom.h
new file mode 100644
index 0000000..8fdb0d2
--- /dev/null
+++ b/arch/x86/include/asm/prom.h
@@ -0,0 +1,60 @@
+/*
+ * Definitions for Device tree / OpenFirmware handling on X86
+ *
+ * based on arch/powerpc/include/asm/prom.h which is
+ * Copyright (C) 1996-2005 Paul Mackerras.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#ifndef _ASM_X86_PROM_H
+#define _ASM_X86_PROM_H
+#ifdef __KERNEL__
+#ifndef __ASSEMBLY__
+
+#include <linux/of.h>
+#include <linux/types.h>
+#include <asm/irq.h>
+#include <asm/atomic.h>
+#include <asm/setup.h>
+
+#ifdef CONFIG_OF
+extern void init_dtb(void);
+extern void add_dtb(u64 data);
+#else
+static inline void init_dtb(void) { }
+static inline void add_dtb(u64 data) { }
+#endif
+
+extern char cmd_line[COMMAND_LINE_SIZE];
+/* This number is used when no interrupt has been assigned */
+#define NO_IRQ (-1)
+
+/**
+ * irq_dispose_mapping - Unmap an interrupt
+ * @virq: linux virq number of the interrupt to unmap
+ *
+ * FIXME: We really should implement proper virq handling like power,
+ * but that's going to be major surgery.
+ */
+static inline void irq_dispose_mapping(unsigned int virq) { }
+
+#define HAVE_ARCH_DEVTREE_FIXUPS
+
+#endif /* __ASSEMBLY__ */
+#endif /* __KERNEL__ */
+
+/*
+ * These includes are put at the bottom because they may contain things
+ * that are overridden by this file. Ideally they shouldn't be included
+ * by this file, but there are a bunch of .c files that currently depend
+ * on it. Eventually they will be cleaned up.
+ */
+#include <linux/of_fdt.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+
+#endif
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 9e13763..e0a00c5 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -109,6 +109,7 @@ obj-$(CONFIG_MICROCODE) += microcode.o
obj-$(CONFIG_X86_CHECK_BIOS_CORRUPTION) += check.o

obj-$(CONFIG_SWIOTLB) += pci-swiotlb.o
+obj-$(CONFIG_X86_OF) += prom.o

###
# 64 bit specific files
diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c
index c752e97..d5970e2 100644
--- a/arch/x86/kernel/irqinit.c
+++ b/arch/x86/kernel/irqinit.c
@@ -25,6 +25,7 @@
#include <asm/setup.h>
#include <asm/i8259.h>
#include <asm/traps.h>
+#include <asm/prom.h>

/*
* ISA PIC or low IO-APIC triggered (INTA-cycle or APIC) interrupts:
@@ -118,6 +119,12 @@ void __init init_IRQ(void)
int i;

/*
+ * We probably need a better place for this, but it works for
+ * now ...
+ */
+ init_dtb();
+
+ /*
* On cpu 0, Assign IRQ0_VECTOR..IRQ15_VECTOR's to IRQ 0..15.
* If these IRQ's are handled by legacy interrupt-controllers like PIC,
* then this configuration will likely be static after the boot. If
diff --git a/arch/x86/kernel/prom.c b/arch/x86/kernel/prom.c
new file mode 100644
index 0000000..ba9a096
--- /dev/null
+++ b/arch/x86/kernel/prom.c
@@ -0,0 +1,60 @@
+/*
+ * Architecture specific OF callbacks.
+ */
+
+#include <linux/io.h>
+#include <linux/list.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/slab.h>
+
+char __initdata cmd_line[COMMAND_LINE_SIZE];
+
+unsigned int irq_create_of_mapping(struct device_node *controller,
+ const u32 *intspec, unsigned int intsize)
+{
+ return intspec[0];
+
+}
+EXPORT_SYMBOL_GPL(irq_create_of_mapping);
+
+unsigned long pci_address_to_pio(phys_addr_t address)
+{
+ BUG();
+}
+EXPORT_SYMBOL_GPL(pci_address_to_pio);
+
+void __init early_init_dt_scan_chosen_arch(unsigned long node)
+{
+ BUG();
+}
+
+void __init early_init_dt_add_memory_arch(u64 base, u64 size)
+{
+ BUG();
+}
+
+u64 __init early_init_dt_alloc_memory_arch(u64 size, u64 align)
+{
+ void *mem;
+
+ mem = kmalloc(size + align, GFP_KERNEL);
+ BUG_ON(!mem);
+ mem = PTR_ALIGN(mem, align);
+ return virt_to_phys(mem);
+}
+
+void __init add_dtb(u64 data)
+{
+ initial_boot_params = (struct boot_param_header *)
+ phys_to_virt((u64) (u32) data +
+ offsetof(struct setup_data, data));
+}
+
+void __init init_dtb(void)
+{
+ if (!initial_boot_params)
+ return;
+
+ unflatten_device_tree();
+}
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 52f10e6..b1e1bcb 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -113,6 +113,7 @@
#endif
#include <asm/mce.h>
#include <asm/alternative.h>
+#include <asm/prom.h>

/*
* end_pfn only includes RAM, while max_pfn_mapped includes all e820 entries.
@@ -441,6 +442,9 @@ static void __init parse_setup_data(void)
case SETUP_E820_EXT:
parse_e820_ext(data);
break;
+ case SETUP_DTB:
+ add_dtb(pa_data);
+ break;
default:
break;
}
--
1.7.3.2


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