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SubjectRe: [PATCH 1/2] OLPC: Add support for calling into Open Firmware


Yinghai Lu wrote:
> 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
>

Is your suggestion to change the filename from "ofw.c" to "ofw_32.c"?
That seems like a good idea to me.



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