Re: [PATCH TIP 02/14] x86: Add device tree support

From: Grant Likely
Date: Wed Feb 16 2011 - 16:26:37 EST

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On Mon, Jan 24, 2011 at 09:58:50AM +0530, Sebastian Andrzej Siewior wrote:
> 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?
>
> Cc: devicetree-discuss@xxxxxxxxxxxxxxxx
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> Signed-off-by: Dirk Brandewie <dirk.brandewie@xxxxxxxxx>

Hi Sebastian,

Relatively minor comments below. You can go ahead and add the
following when you respin:

Acked-by: Grant Likely <grant.likely@xxxxxxxxxxxx>

> ---
> Documentation/x86/boot_with_dtb.txt | 26 +++++++++++++++
> arch/x86/Kconfig | 7 ++++
> arch/x86/include/asm/bootparam.h | 1 +
> arch/x86/include/asm/irq.h | 3 --
> arch/x86/include/asm/prom.h | 60 ++++++++++++++++++++++++++++++++++-
> arch/x86/kernel/Makefile | 1 +
> arch/x86/kernel/irq.c | 9 -----
> arch/x86/kernel/irqinit.c | 1 +
> arch/x86/kernel/prom.c | 51 +++++++++++++++++++++++++++++
> arch/x86/kernel/setup.c | 4 ++
> 10 files changed, 150 insertions(+), 13 deletions(-)
> create mode 100644 Documentation/x86/boot_with_dtb.txt
> 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..6a357aa
> --- /dev/null
> +++ b/Documentation/x86/boot_with_dtb.txt
> @@ -0,0 +1,26 @@
> + Booting x86 with device tree
> +=================================
> +
> +1. Introduction
> +~~~~~~~~~~~~~~~
> +This document contains device tree information 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 at least boot protocol 2.09. The type filed is
> +defined as
> +
> +#define SETUP_DTB 2
> +
> +3. Purpose
> +~~~~~~~~~~~
> +The device tree is used as an extension to the "boot page". As such it does not
> +parse / consider data which are already covered by the boot page. This includes
> +memory size, command line arguments or initrd address.
> +It simply holds information which can not be retrieved otherwise like interrupt
> +routing or a list of devices behind an I2C bus.
> +
> +[0] Documentation/x86/boot.txt

Please also add a brief description to section I of
Documentation/devicetree/booting-without-of.txt

> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index d5ed94d..5d21095 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -297,6 +297,13 @@ 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_EARLY_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/irq.h b/arch/x86/include/asm/irq.h
> index c704b38..ba870bb 100644
> --- a/arch/x86/include/asm/irq.h
> +++ b/arch/x86/include/asm/irq.h
> @@ -10,9 +10,6 @@
> #include <asm/apicdef.h>
> #include <asm/irq_vectors.h>
>
> -/* Even though we don't support this, supply it to appease OF */
> -static inline void irq_dispose_mapping(unsigned int virq) { }
> -
> static inline int irq_canonicalize(int irq)
> {
> return ((irq == 2) ? 9 : irq);
> diff --git a/arch/x86/include/asm/prom.h b/arch/x86/include/asm/prom.h
> index b4ec95f..b227ba7 100644
> --- a/arch/x86/include/asm/prom.h
> +++ b/arch/x86/include/asm/prom.h
> @@ -1 +1,59 @@
> -/* dummy prom.h; here to make linux/of.h's #includes happy */
> +/*
> + * 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
> +#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 add_dtb(u64 data);
> +#else
> +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 (0)

This line should no longer be necessary. drivers/of/irq.c defines
NO_IRQ if it isn't already defined by the architecture. I'm trying to
limit the exposure of NO_IRQ in dt code.

> +
> +#define pci_address_to_pio pci_address_to_pio
> +unsigned long pci_address_to_pio(phys_addr_t addr);
> +
> +/**
> + * 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.

Lennert Buytenhek is working on this. It actually shouldn't be too
bad.

> + */
> +static inline void irq_dispose_mapping(unsigned int virq) { }
> +
> +#define HAVE_ARCH_DEVTREE_FIXUPS
> +
> +#endif /* __ASSEMBLY__ */
> +
> +/*
> + * 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>

You should be able to remove these includes. The problems described
in the header are mostly with device drivers and architecture code.
You shouldn't run into any of those issue, and if you do they should
be fixed at the source.

> +
> +#endif
> diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
> index 34244b2..50ff982 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/irq.c b/arch/x86/kernel/irq.c
> index 52945da..45cdc62 100644
> --- a/arch/x86/kernel/irq.c
> +++ b/arch/x86/kernel/irq.c
> @@ -276,15 +276,6 @@ void smp_x86_platform_ipi(struct pt_regs *regs)
>
> EXPORT_SYMBOL_GPL(vector_used_by_percpu_irq);
>
> -#ifdef CONFIG_OF
> -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);
> -#endif
> -
> #ifdef CONFIG_HOTPLUG_CPU
> /* A cpu has been removed from cpu_online_mask. Reset irq affinities. */
> void fixup_irqs(void)
> diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c
> index c752e97..149c87f 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>

I'm probably missing something. I don't see any changes to irqinit.c
other than this. What symbol definition has been moved to prom.h that
irqinit.c needs?

>
> /*
> * ISA PIC or low IO-APIC triggered (INTA-cycle or APIC) interrupts:
> diff --git a/arch/x86/kernel/prom.c b/arch/x86/kernel/prom.c
> new file mode 100644
> index 0000000..4969ffa
> --- /dev/null
> +++ b/arch/x86/kernel/prom.c

You don't need to name this prom.c. devicetree.c would make more sense.
prom is a legacy name from when only Open Firmware systems were using
the dt code.

> @@ -0,0 +1,51 @@
> +/*
> + * Architecture specific OF callbacks.
> + */
> +#include <linux/bootmem.h>
> +#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)
> +{
> + /*
> + * The ioport address can be directly used by inX / outX
> + */
> + BUG_ON(address >= (1 << 16));
> + return (unsigned long)address;
> +}
> +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();
> +}
> +
> +void * __init early_init_dt_alloc_memory_arch(u64 size, u64 align)
> +{
> + return __alloc_bootmem(size, align, __pa(MAX_DMA_ADDRESS));
> +}
> +
> +void __init add_dtb(u64 data)
> +{
> + initial_boot_params = (struct boot_param_header *)
> + phys_to_virt((u64) (u32) data +
> + offsetof(struct setup_data, data));

(struct boot_param_header *) cast unnecessary since phys_to_virt
should return a void*.

> +}
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index f8e7152..87396d2 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.
> @@ -446,6 +447,9 @@ 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
>
> _______________________________________________
> devicetree-discuss mailing list
> devicetree-discuss@xxxxxxxxxxxxxxxx
> https://lists.ozlabs.org/listinfo/devicetree-discuss
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Next message: Grant Likely: "Re: [PATCH TIP 02/14] x86: Add device tree support"
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