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

[Mitch Bradley]

Yinghai Lu wrote:
> On Sat, Apr 19, 2008 at 10:39 AM, Andres Salomon <dilinger@xxxxxxxxxx> 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@xxxxxxxxxx>
> >  ---
> >   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@xxxxxxxxxxxxx>
> >  + * Copyright (c) 2007-2008  Andres Salomon <dilinger@xxxxxxxxxx>
> >  + *
> >  + * 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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