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SubjectRe: [PATCH 1/2] OLPC: Add support for calling into Open Firmware
On Sat, Apr 19, 2008 at 10:39 AM, Andres Salomon <dilinger@queued.net> wrote:
>
> This adds 32-bit support for calling into OFW from the kernel. It's useful
> for querying the firmware for misc hardware information, fetching the device
> tree, etc.
>
> There's potentially no reason why other platforms couldn't use this, but
> currently OLPC is the main user of it.
>
> This work was originally done by Mitch Bradley.
>
> Signed-off-by: Andres Salomon <dilinger@debian.org>
> ---
> arch/x86/Kconfig | 8 +++++
> arch/x86/kernel/Makefile | 1 +
> arch/x86/kernel/head_32.S | 27 ++++++++++++++++
> arch/x86/kernel/ofw.c | 75 +++++++++++++++++++++++++++++++++++++++++++++
> include/asm-x86/ofw.h | 50 ++++++++++++++++++++++++++++++
> include/asm-x86/setup.h | 1 +
> 6 files changed, 162 insertions(+), 0 deletions(-)
> create mode 100644 arch/x86/kernel/ofw.c
> create mode 100644 include/asm-x86/ofw.h
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 3b9089b..ce56105 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -661,6 +661,14 @@ config I8K
> Say Y if you intend to run this kernel on a Dell Inspiron 8000.
> Say N otherwise.
>
> +config OPEN_FIRMWARE
> + bool "Support for Open Firmware"
> + default y if OLPC
> + ---help---
> + This option adds support for the implementation of Open Firmware
> + that is used on the OLPC XO laptop.
> + If unsure, say N here.
> +
> config X86_REBOOTFIXUPS
> def_bool n
> prompt "Enable X86 board specific fixups for reboot"
> diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
> index 9575754..d33600e 100644
> --- a/arch/x86/kernel/Makefile
> +++ b/arch/x86/kernel/Makefile
> @@ -54,6 +54,7 @@ obj-$(CONFIG_X86_TRAMPOLINE) += trampoline_$(BITS).o
> obj-$(CONFIG_X86_MPPARSE) += mpparse_$(BITS).o
> obj-$(CONFIG_X86_LOCAL_APIC) += apic_$(BITS).o nmi_$(BITS).o
> obj-$(CONFIG_X86_IO_APIC) += io_apic_$(BITS).o
> +obj-$(CONFIG_OPEN_FIRMWARE) += ofw.o
> obj-$(CONFIG_X86_REBOOTFIXUPS) += reboot_fixups_32.o
> obj-$(CONFIG_KEXEC) += machine_kexec_$(BITS).o
> obj-$(CONFIG_KEXEC) += relocate_kernel_$(BITS).o crash.o
> diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
> index 74d87ea..c9d2d00 100644
> --- a/arch/x86/kernel/head_32.S
> +++ b/arch/x86/kernel/head_32.S
> @@ -132,6 +132,33 @@ ENTRY(startup_32)
> movsl
> 1:
>
> +#ifdef CONFIG_OPEN_FIRMWARE
> +/*
> + * If Open Firmware booted us, save the OFW client interface callback address
> + * and preserve the OFW page mappings by priming the kernel's new page
> + * directory area with a copy of the OFW page directory. That lets OFW stay
> + * resident in high memory (high in both the virtual and physical spaces)
> + * for at least long enough to copy out the device tree.
> + */
> + movl $pa(boot_params + OFW_INFO_OFFSET), %ebp
> + cmpl $0x2057464F, (%ebp) /* Magic number "OFW " */
> + jne 4f
> +
> + mov 0x8(%ebp), %eax /* Save callback address */
> + mov %eax, pa(call_firmware)
> +
> + /* Copy the OFW pdir into swapper_pg_dir */
> + movl %esi, %edx /* save %esi */
> + movl $pa(swapper_pg_dir), %edi
> + movl %cr3, %esi /* Source is current pg_dir base address */
> + movl $1024, %ecx /* Number of page directory entries */
> + rep
> + movsl
> + movl %edx, %esi /* restore %esi */
> +4:
> +
> +#endif
> +
> #ifdef CONFIG_PARAVIRT
> /* This is can only trip for a broken bootloader... */
> cmpw $0x207, pa(boot_params + BP_version)
> diff --git a/arch/x86/kernel/ofw.c b/arch/x86/kernel/ofw.c
> new file mode 100644
> index 0000000..14036aa
> --- /dev/null
> +++ b/arch/x86/kernel/ofw.c
> @@ -0,0 +1,75 @@
> +/*
> + * Open Firmware client interface for 32-bit systems.
> + *
> + * Copyright (c) 2007 Mitch Bradley <wmb@firmworks.com>
> + * Copyright (c) 2007-2008 Andres Salomon <dilinger@debian.org>
> + *
> + * 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.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/spinlock.h>
> +#include <linux/module.h>
> +#include <asm/ofw.h>
> +
> +/*
> + * This code is intended to be portable to any 32-bit Open Firmware
> + * implementation with a standard client interface that can be
> + * called when Linux is running.

how about changing to ofw_32.c?

YH


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