Patchwork [2/4] sparc: break out some prom device-tree building code out into drivers/of

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Submitter Andres Salomon
Date June 29, 2010, 2 a.m.
Message ID <20100628220037.5744c207@debian>
Download mbox | patch
Permalink /patch/57218/
State Not Applicable
Delegated to: David Miller
Headers show

Comments

Andres Salomon - June 29, 2010, 2 a.m.
Stick code into drivers/of/pdt.c (Prom Device Tree) that other
architectures with OpenFirmware resident in memory can make use of.

Signed-off-by: Andres Salomon <dilinger@queued.net>
---
 arch/sparc/Kconfig              |    1 +
 arch/sparc/include/asm/prom.h   |   15 +++-
 arch/sparc/kernel/prom.h        |   14 ---
 arch/sparc/kernel/prom_common.c |  173 +------------------------------
 drivers/of/Kconfig              |    4 +
 drivers/of/Makefile             |    1 +
 drivers/of/pdt.c                |  225 +++++++++++++++++++++++++++++++++++++++
 include/linux/of_pdt.h          |   37 +++++++
 8 files changed, 282 insertions(+), 188 deletions(-)
 create mode 100644 drivers/of/pdt.c
 create mode 100644 include/linux/of_pdt.h
David Miller - June 29, 2010, 3:11 a.m.
From: Andres Salomon <dilinger@queued.net>
Date: Mon, 28 Jun 2010 22:00:37 -0400

> 
> Stick code into drivers/of/pdt.c (Prom Device Tree) that other
> architectures with OpenFirmware resident in memory can make use of.
> 
> Signed-off-by: Andres Salomon <dilinger@queued.net>

Acked-by: David S. Miller <davem@davemloft.net>
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Stephen Rothwell - June 29, 2010, 6:15 a.m.
Hi Andres,

On Mon, 28 Jun 2010 22:00:37 -0400 Andres Salomon <dilinger@queued.net> wrote:
>
> diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
> index 6f1470b..b4cb63b 100644
> --- a/arch/sparc/Kconfig
> +++ b/arch/sparc/Kconfig
> @@ -150,6 +150,7 @@ config ARCH_NO_VIRT_TO_BUS
>  
>  config OF
>  	def_bool y
> +	select OF_PROMTREE

Please put this select in CONFIG_SPARC instead as we want to move
CONFIG_OF to drivers/og/Kconfig
Grant Likely - June 29, 2010, 7:50 a.m.
On Mon, Jun 28, 2010 at 7:00 PM, Andres Salomon <dilinger@queued.net> wrote:
>
> Stick code into drivers/of/pdt.c (Prom Device Tree) that other
> architectures with OpenFirmware resident in memory can make use of.
>
> Signed-off-by: Andres Salomon <dilinger@queued.net>

Hi Andres,

The patch itself looks fine, but there are currently two methods for
extracting the device tree from open firmware; one in arch/powerpc
using the flattened format, and one in arch/sparc.  I don't want to
end up maintaining both methods in drivers/of, and there has also some
discussions on moving the powerpc version into common code.  I've been
thinking about using the powerpc approach to support ARM platforms
using both the flat tree and real OFW.

Ben, what say you?  Before I do anything I'd like to have your opinion.

Cheers,
g.

> ---
>  arch/sparc/Kconfig              |    1 +
>  arch/sparc/include/asm/prom.h   |   15 +++-
>  arch/sparc/kernel/prom.h        |   14 ---
>  arch/sparc/kernel/prom_common.c |  173 +------------------------------
>  drivers/of/Kconfig              |    4 +
>  drivers/of/Makefile             |    1 +
>  drivers/of/pdt.c                |  225 +++++++++++++++++++++++++++++++++++++++
>  include/linux/of_pdt.h          |   37 +++++++
>  8 files changed, 282 insertions(+), 188 deletions(-)
>  create mode 100644 drivers/of/pdt.c
>  create mode 100644 include/linux/of_pdt.h
>
> diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
> index 6f1470b..b4cb63b 100644
> --- a/arch/sparc/Kconfig
> +++ b/arch/sparc/Kconfig
> @@ -150,6 +150,7 @@ config ARCH_NO_VIRT_TO_BUS
>
>  config OF
>        def_bool y
> +       select OF_PROMTREE
>
>  config ARCH_SUPPORTS_DEBUG_PAGEALLOC
>        def_bool y if SPARC64
> diff --git a/arch/sparc/include/asm/prom.h b/arch/sparc/include/asm/prom.h
> index f845828..0834c2a 100644
> --- a/arch/sparc/include/asm/prom.h
> +++ b/arch/sparc/include/asm/prom.h
> @@ -18,6 +18,7 @@
>  * 2 of the License, or (at your option) any later version.
>  */
>  #include <linux/types.h>
> +#include <linux/of_pdt.h>
>  #include <linux/proc_fs.h>
>  #include <linux/mutex.h>
>  #include <asm/atomic.h>
> @@ -65,8 +66,18 @@ extern struct device_node *of_console_device;
>  extern char *of_console_path;
>  extern char *of_console_options;
>
> -extern void (*prom_build_more)(struct device_node *dp, struct device_node ***nextp);
> -extern char *build_full_name(struct device_node *dp);
> +/* stuff used by of/pdt */
> +extern void * prom_early_alloc(unsigned long size);
> +extern void irq_trans_init(struct device_node *dp);
> +extern char *build_path_component(struct device_node *dp);
> +
> +extern char *prom_firstprop(int node, char *buffer);
> +extern char *prom_nextprop(int node, const char *oprop, char *buffer);
> +extern int prom_getproplen(int node, const char *prop);
> +extern int prom_getproperty(int node, const char *prop,
> +                           char *buffer, int bufsize);
> +extern int prom_getchild(int node);
> +extern int prom_getsibling(int node);
>
>  #endif /* __KERNEL__ */
>  #endif /* _SPARC_PROM_H */
> diff --git a/arch/sparc/kernel/prom.h b/arch/sparc/kernel/prom.h
> index a8591ef..cf5fe1c 100644
> --- a/arch/sparc/kernel/prom.h
> +++ b/arch/sparc/kernel/prom.h
> @@ -4,20 +4,6 @@
>  #include <linux/spinlock.h>
>  #include <asm/prom.h>
>
> -extern void * prom_early_alloc(unsigned long size);
> -extern void irq_trans_init(struct device_node *dp);
> -
> -extern unsigned int prom_unique_id;
> -
> -static inline int is_root_node(const struct device_node *dp)
> -{
> -       if (!dp)
> -               return 0;
> -
> -       return (dp->parent == NULL);
> -}
> -
> -extern char *build_path_component(struct device_node *dp);
>  extern void of_console_init(void);
>
>  extern unsigned int prom_early_allocated;
> diff --git a/arch/sparc/kernel/prom_common.c b/arch/sparc/kernel/prom_common.c
> index 57ac9e2..fc990e1 100644
> --- a/arch/sparc/kernel/prom_common.c
> +++ b/arch/sparc/kernel/prom_common.c
> @@ -20,14 +20,13 @@
>  #include <linux/mutex.h>
>  #include <linux/slab.h>
>  #include <linux/of.h>
> +#include <linux/of_pdt.h>
>  #include <asm/prom.h>
>  #include <asm/oplib.h>
>  #include <asm/leon.h>
>
>  #include "prom.h"
>
> -void (*prom_build_more)(struct device_node *dp, struct device_node ***nextp);
> -
>  struct device_node *of_console_device;
>  EXPORT_SYMBOL(of_console_device);
>
> @@ -119,176 +118,6 @@ int of_find_in_proplist(const char *list, const char *match, int len)
>  }
>  EXPORT_SYMBOL(of_find_in_proplist);
>
> -unsigned int prom_unique_id;
> -
> -static struct property * __init build_one_prop(phandle node, char *prev,
> -                                              char *special_name,
> -                                              void *special_val,
> -                                              int special_len)
> -{
> -       static struct property *tmp = NULL;
> -       struct property *p;
> -       const char *name;
> -
> -       if (tmp) {
> -               p = tmp;
> -               memset(p, 0, sizeof(*p) + 32);
> -               tmp = NULL;
> -       } else {
> -               p = prom_early_alloc(sizeof(struct property) + 32);
> -               p->unique_id = prom_unique_id++;
> -       }
> -
> -       p->name = (char *) (p + 1);
> -       if (special_name) {
> -               strcpy(p->name, special_name);
> -               p->length = special_len;
> -               p->value = prom_early_alloc(special_len);
> -               memcpy(p->value, special_val, special_len);
> -       } else {
> -               if (prev == NULL) {
> -                       name = prom_firstprop(node, p->name);
> -               } else {
> -                       name = prom_nextprop(node, prev, p->name);
> -               }
> -
> -               if (!name || strlen(name) == 0) {
> -                       tmp = p;
> -                       return NULL;
> -               }
> -#ifdef CONFIG_SPARC32
> -               strcpy(p->name, name);
> -#endif
> -               p->length = prom_getproplen(node, p->name);
> -               if (p->length <= 0) {
> -                       p->length = 0;
> -               } else {
> -                       int len;
> -
> -                       p->value = prom_early_alloc(p->length + 1);
> -                       len = prom_getproperty(node, p->name, p->value,
> -                                              p->length);
> -                       if (len <= 0)
> -                               p->length = 0;
> -                       ((unsigned char *)p->value)[p->length] = '\0';
> -               }
> -       }
> -       return p;
> -}
> -
> -static struct property * __init build_prop_list(phandle node)
> -{
> -       struct property *head, *tail;
> -
> -       head = tail = build_one_prop(node, NULL,
> -                                    ".node", &node, sizeof(node));
> -
> -       tail->next = build_one_prop(node, NULL, NULL, NULL, 0);
> -       tail = tail->next;
> -       while(tail) {
> -               tail->next = build_one_prop(node, tail->name,
> -                                           NULL, NULL, 0);
> -               tail = tail->next;
> -       }
> -
> -       return head;
> -}
> -
> -static char * __init get_one_property(phandle node, const char *name)
> -{
> -       char *buf = "<NULL>";
> -       int len;
> -
> -       len = prom_getproplen(node, name);
> -       if (len > 0) {
> -               buf = prom_early_alloc(len);
> -               len = prom_getproperty(node, name, buf, len);
> -       }
> -
> -       return buf;
> -}
> -
> -static struct device_node * __init prom_create_node(phandle node,
> -                                                   struct device_node *parent)
> -{
> -       struct device_node *dp;
> -
> -       if (!node)
> -               return NULL;
> -
> -       dp = prom_early_alloc(sizeof(*dp));
> -       dp->unique_id = prom_unique_id++;
> -       dp->parent = parent;
> -
> -       kref_init(&dp->kref);
> -
> -       dp->name = get_one_property(node, "name");
> -       dp->type = get_one_property(node, "device_type");
> -       dp->phandle = node;
> -
> -       dp->properties = build_prop_list(node);
> -
> -       irq_trans_init(dp);
> -
> -       return dp;
> -}
> -
> -char * __init build_full_name(struct device_node *dp)
> -{
> -       int len, ourlen, plen;
> -       char *n;
> -
> -       plen = strlen(dp->parent->full_name);
> -       ourlen = strlen(dp->path_component_name);
> -       len = ourlen + plen + 2;
> -
> -       n = prom_early_alloc(len);
> -       strcpy(n, dp->parent->full_name);
> -       if (!is_root_node(dp->parent)) {
> -               strcpy(n + plen, "/");
> -               plen++;
> -       }
> -       strcpy(n + plen, dp->path_component_name);
> -
> -       return n;
> -}
> -
> -static struct device_node * __init prom_build_tree(struct device_node *parent,
> -                                                  phandle node,
> -                                                  struct device_node ***nextp)
> -{
> -       struct device_node *ret = NULL, *prev_sibling = NULL;
> -       struct device_node *dp;
> -
> -       while (1) {
> -               dp = prom_create_node(node, parent);
> -               if (!dp)
> -                       break;
> -
> -               if (prev_sibling)
> -                       prev_sibling->sibling = dp;
> -
> -               if (!ret)
> -                       ret = dp;
> -               prev_sibling = dp;
> -
> -               *(*nextp) = dp;
> -               *nextp = &dp->allnext;
> -
> -               dp->path_component_name = build_path_component(dp);
> -               dp->full_name = build_full_name(dp);
> -
> -               dp->child = prom_build_tree(dp, prom_getchild(node), nextp);
> -
> -               if (prom_build_more)
> -                       prom_build_more(dp, nextp);
> -
> -               node = prom_getsibling(node);
> -       }
> -
> -       return ret;
> -}
> -
>  unsigned int prom_early_allocated __initdata;
>
>  void __init prom_build_devicetree(void)
> diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
> index 7cecc8f..41921a8 100644
> --- a/drivers/of/Kconfig
> +++ b/drivers/of/Kconfig
> @@ -2,6 +2,10 @@ config OF_FLATTREE
>        bool
>        depends on OF
>
> +config OF_PROMTREE
> +       bool
> +       depends on OF
> +
>  config OF_DYNAMIC
>        def_bool y
>        depends on OF && PPC_OF
> diff --git a/drivers/of/Makefile b/drivers/of/Makefile
> index f232cc9..54e8517 100644
> --- a/drivers/of/Makefile
> +++ b/drivers/of/Makefile
> @@ -1,5 +1,6 @@
>  obj-y = base.o
>  obj-$(CONFIG_OF_FLATTREE) += fdt.o
> +obj-$(CONFIG_OF_PROMTREE) += pdt.o
>  obj-$(CONFIG_OF_DEVICE) += device.o platform.o
>  obj-$(CONFIG_OF_GPIO)   += gpio.o
>  obj-$(CONFIG_OF_I2C)   += of_i2c.o
> diff --git a/drivers/of/pdt.c b/drivers/of/pdt.c
> new file mode 100644
> index 0000000..b24167f
> --- /dev/null
> +++ b/drivers/of/pdt.c
> @@ -0,0 +1,225 @@
> +/*
> + * Paul Mackerras      August 1996.
> + * Copyright (C) 1996-2005 Paul Mackerras.
> + *
> + *  Adapted for 64bit PowerPC by Dave Engebretsen and Peter Bergner.
> + *    {engebret|bergner}@us.ibm.com
> + *
> + *  Adapted for sparc by David S. Miller davem@davemloft.net
> + *  Adapted for multiple architectures by Andres Salomon <dilinger@queued.net>
> + *
> + *      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/module.h>
> +#include <linux/errno.h>
> +#include <linux/mutex.h>
> +#include <linux/slab.h>
> +#include <linux/of.h>
> +#include <linux/of_pdt.h>
> +#include <asm/prom.h>
> +
> +/* TODO: mark this stuff as __initdata */
> +void (*prom_build_more)(struct device_node *dp, struct device_node ***nextp);
> +
> +#if defined(CONFIG_SPARC)
> +static unsigned int prom_unique_id;
> +
> +#define inc_unique_id(p) do { \
> +       (p)->unique_id = prom_unique_id++; \
> +} while (0)
> +
> +static inline const char *fetch_node_name(struct device_node *dp)
> +{
> +       return dp->path_component_name;
> +}
> +
> +#else
> +
> +#define inc_unique_id(p)       do { } while(0)
> +
> +static inline const char *fetch_node_name(struct device_node *dp)
> +{
> +       return dp->name;
> +}
> +
> +static inline void irq_trans_init(struct device_node *dp)
> +{
> +       /* unused on non-SPARC architectures */
> +}
> +
> +#endif /* !CONFIG_SPARC */
> +
> +static struct property * __init build_one_prop(phandle node, char *prev,
> +                                              char *special_name,
> +                                              void *special_val,
> +                                              int special_len)
> +{
> +       static struct property *tmp = NULL;
> +       struct property *p;
> +       const char *name;
> +
> +       if (tmp) {
> +               p = tmp;
> +               memset(p, 0, sizeof(*p) + 32);
> +               tmp = NULL;
> +       } else {
> +               p = prom_early_alloc(sizeof(struct property) + 32);
> +               inc_unique_id(p);
> +       }
> +
> +       p->name = (char *) (p + 1);
> +       if (special_name) {
> +               strcpy(p->name, special_name);
> +               p->length = special_len;
> +               p->value = prom_early_alloc(special_len);
> +               memcpy(p->value, special_val, special_len);
> +       } else {
> +               if (prev == NULL) {
> +                       name = prom_firstprop(node, p->name);
> +               } else {
> +                       name = prom_nextprop(node, prev, p->name);
> +               }
> +
> +               if (!name || strlen(name) == 0) {
> +                       tmp = p;
> +                       return NULL;
> +               }
> +#ifdef CONFIG_SPARC32
> +               strcpy(p->name, name);
> +#endif
> +               p->length = prom_getproplen(node, p->name);
> +               if (p->length <= 0) {
> +                       p->length = 0;
> +               } else {
> +                       int len;
> +
> +                       p->value = prom_early_alloc(p->length + 1);
> +                       len = prom_getproperty(node, p->name, p->value,
> +                                              p->length);
> +                       if (len <= 0)
> +                               p->length = 0;
> +                       ((unsigned char *)p->value)[p->length] = '\0';
> +               }
> +       }
> +       return p;
> +}
> +
> +static struct property * __init build_prop_list(phandle node)
> +{
> +       struct property *head, *tail;
> +
> +       head = tail = build_one_prop(node, NULL,
> +                                    ".node", &node, sizeof(node));
> +
> +       tail->next = build_one_prop(node, NULL, NULL, NULL, 0);
> +       tail = tail->next;
> +       while(tail) {
> +               tail->next = build_one_prop(node, tail->name,
> +                                           NULL, NULL, 0);
> +               tail = tail->next;
> +       }
> +
> +       return head;
> +}
> +
> +static char * __init get_one_property(phandle node, const char *name)
> +{
> +       char *buf = "<NULL>";
> +       int len;
> +
> +       len = prom_getproplen(node, name);
> +       if (len > 0) {
> +               buf = prom_early_alloc(len);
> +               len = prom_getproperty(node, name, buf, len);
> +       }
> +
> +       return buf;
> +}
> +
> +struct device_node * __init prom_create_node(phandle node,
> +                                            struct device_node *parent)
> +{
> +       struct device_node *dp;
> +
> +       if (!node)
> +               return NULL;
> +
> +       dp = prom_early_alloc(sizeof(*dp));
> +       inc_unique_id(dp);
> +       dp->parent = parent;
> +
> +       kref_init(&dp->kref);
> +
> +       dp->name = get_one_property(node, "name");
> +       dp->type = get_one_property(node, "device_type");
> +       dp->phandle = node;
> +
> +       dp->properties = build_prop_list(node);
> +
> +       irq_trans_init(dp);
> +
> +       return dp;
> +}
> +
> +static char * __init build_full_name(struct device_node *dp)
> +{
> +       int len, ourlen, plen;
> +       char *n;
> +
> +       plen = strlen(dp->parent->full_name);
> +       ourlen = strlen(fetch_node_name(dp));
> +       len = ourlen + plen + 2;
> +
> +       n = prom_early_alloc(len);
> +       strcpy(n, dp->parent->full_name);
> +       if (!is_root_node(dp->parent)) {
> +               strcpy(n + plen, "/");
> +               plen++;
> +       }
> +       strcpy(n + plen, fetch_node_name(dp));
> +
> +       return n;
> +}
> +
> +struct device_node * __init prom_build_tree(struct device_node *parent,
> +                                           phandle node,
> +                                           struct device_node ***nextp)
> +{
> +       struct device_node *ret = NULL, *prev_sibling = NULL;
> +       struct device_node *dp;
> +
> +       while (1) {
> +               dp = prom_create_node(node, parent);
> +               if (!dp)
> +                       break;
> +
> +               if (prev_sibling)
> +                       prev_sibling->sibling = dp;
> +
> +               if (!ret)
> +                       ret = dp;
> +               prev_sibling = dp;
> +
> +               *(*nextp) = dp;
> +               *nextp = &dp->allnext;
> +
> +#if defined(CONFIG_SPARC)
> +               dp->path_component_name = build_path_component(dp);
> +#endif
> +               dp->full_name = build_full_name(dp);
> +
> +               dp->child = prom_build_tree(dp, prom_getchild(node), nextp);
> +
> +               if (prom_build_more)
> +                       prom_build_more(dp, nextp);
> +
> +               node = prom_getsibling(node);
> +       }
> +
> +       return ret;
> +}
> diff --git a/include/linux/of_pdt.h b/include/linux/of_pdt.h
> new file mode 100644
> index 0000000..f62616e
> --- /dev/null
> +++ b/include/linux/of_pdt.h
> @@ -0,0 +1,37 @@
> +#include <linux/of.h>  /* linux/of.h gets to determine #include ordering */
> +/*
> + * Definitions for building a device tree by calling into the
> + * Open Firmware PROM.
> + *
> + * Copyright (C) 1996-2005 Paul Mackerras.
> + * Copyright (C) 2010  Andres Salomon <dilinger@queued.net>
> + *
> + * Updates for PPC64 by Peter Bergner & David Engebretsen, IBM Corp.
> + * Updates for SPARC by David S. Miller
> + *
> + * 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 _LINUX_OF_PDT_H
> +#define _LINUX_OF_PDT_H
> +
> +extern struct device_node *prom_create_node(phandle node,
> +                                           struct device_node *parent);
> +extern struct device_node *prom_build_tree(struct device_node *parent,
> +                                          phandle node,
> +                                          struct device_node ***nextp);
> +
> +extern void (*prom_build_more)(struct device_node *dp, struct device_node ***nextp);
> +
> +static inline int is_root_node(const struct device_node *dp)
> +{
> +       if (!dp)
> +               return 0;
> +
> +       return (dp->parent == NULL);
> +}
> +
> +#endif /* _LINUX_OF_PDT_H */
> --
> 1.5.6.5
>
>
Andres Salomon - June 29, 2010, 3:03 p.m.
On Tue, 29 Jun 2010 00:50:08 -0700
Grant Likely <grant.likely@secretlab.ca> wrote:

> On Mon, Jun 28, 2010 at 7:00 PM, Andres Salomon <dilinger@queued.net> wrote:
> >
> > Stick code into drivers/of/pdt.c (Prom Device Tree) that other
> > architectures with OpenFirmware resident in memory can make use of.
> >
> > Signed-off-by: Andres Salomon <dilinger@queued.net>
> 
> Hi Andres,
> 
> The patch itself looks fine, but there are currently two methods for
> extracting the device tree from open firmware; one in arch/powerpc
> using the flattened format, and one in arch/sparc.  I don't want to
> end up maintaining both methods in drivers/of, and there has also some
> discussions on moving the powerpc version into common code.  I've been
> thinking about using the powerpc approach to support ARM platforms
> using both the flat tree and real OFW.
> 
> Ben, what say you?  Before I do anything I'd like to have your opinion.
> 

So you're saying that you want ARM (and sparc, and OLPC) to generate a
flat tree by calling into OFW?  Sparc and OLPC have very similar
mechanisms for getting device tree info from OFW, so it makes sense to
share code between them.


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Grant Likely - June 29, 2010, 9:42 p.m.
On Tue, Jun 29, 2010 at 9:03 AM, Andres Salomon <dilinger@queued.net> wrote:
> On Tue, 29 Jun 2010 00:50:08 -0700
> Grant Likely <grant.likely@secretlab.ca> wrote:
>
>> On Mon, Jun 28, 2010 at 7:00 PM, Andres Salomon <dilinger@queued.net> wrote:
>> >
>> > Stick code into drivers/of/pdt.c (Prom Device Tree) that other
>> > architectures with OpenFirmware resident in memory can make use of.
>> >
>> > Signed-off-by: Andres Salomon <dilinger@queued.net>
>>
>> Hi Andres,
>>
>> The patch itself looks fine, but there are currently two methods for
>> extracting the device tree from open firmware; one in arch/powerpc
>> using the flattened format, and one in arch/sparc.  I don't want to
>> end up maintaining both methods in drivers/of, and there has also some
>> discussions on moving the powerpc version into common code.  I've been
>> thinking about using the powerpc approach to support ARM platforms
>> using both the flat tree and real OFW.
>>
>> Ben, what say you?  Before I do anything I'd like to have your opinion.
>>
>
> So you're saying that you want ARM (and sparc, and OLPC) to generate a
> flat tree by calling into OFW?

ARM: yes, it will use the same mechanism as powerpc and microblaze.
Direct usage of the flat representation will be more common that
machines with real OFW.  I'm following the powerpc lead here because
the powerpc approach already supports both the flat tree and OFW in
the same kernel.

Sparc: I don't have a strong opinion.  Sparc and PowerPC have a lot of
shared code, but they've diverged quite a bit.  I have no intention to
force a model changes onto sparc.  For a lot of the merge work that
I'm doing I'm leaving the sparc code as-is in the arch/sparc tree with
the assumption that support for new architectures will use the common
code in drivers/of.

There of course is a gap when it comes to talking to OFW in that both
the current powerpc and sparc variants still remain in arch code.

x86:  I've also just received patches that make use of the flattened
representation on x86 for FPGA add in boards.  It is conceivable that
a single kernel will want support for both OFW and FDT.  Since PowerPC
already supports this use case, my preference is for the powerpc
implementation of OFW.

I'm squeamish about having both the powerpc and sparc methods in
common drivers/of code, but I'm not saying no.  I want to hear from
Ben and David who are more familiar with the history before I make a
decision.  I do know that Ben has been talking about generalizing the
powerpc version of the code, and I definitely don't want two methods
for extracting the OFW device tree in drivers/of.

>  Sparc and OLPC have very similar
> mechanisms for getting device tree info from OFW, so it makes sense to
> share code between them.

Other than the flattened tree step; is the powerpc method dissimilar
from the Sparc and OLPC method for talking to OFW?  (This is not a
rhetorical question, I'm want to know if I'm missing some details).
The main difference I know about is that OFW can still kept alive at
runtime for sparc, which powerpc does not do.  However, keeping OFW
callable is a separate issue from how to extract the device tree.

g.
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Andres Salomon - June 29, 2010, 11:36 p.m.
On Tue, 29 Jun 2010 15:42:54 -0600
Grant Likely <grant.likely@secretlab.ca> wrote:

> On Tue, Jun 29, 2010 at 9:03 AM, Andres Salomon <dilinger@queued.net>
> wrote:
[...]
> 
> >  Sparc and OLPC have very similar
> > mechanisms for getting device tree info from OFW, so it makes sense
> > to share code between them.
> 
> Other than the flattened tree step; is the powerpc method dissimilar
> from the Sparc and OLPC method for talking to OFW?  (This is not a
> rhetorical question, I'm want to know if I'm missing some details).
> The main difference I know about is that OFW can still kept alive at
> runtime for sparc, which powerpc does not do.  However, keeping OFW
> callable is a separate issue from how to extract the device tree.
> 

After having a look at powerpc's flatten_device_tree, I don't see any
obvious reason why OLPC couldn't use this (though it still strikes me
as weird to go from prom->fdt->dt when the option of prom->dt is
available and less complex). Do you already have the patches that put
this into drivers/of/?
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Grant Likely - June 30, 2010, 9:52 p.m.
On Tue, Jun 29, 2010 at 5:36 PM, Andres Salomon <dilinger@queued.net> wrote:
> On Tue, 29 Jun 2010 15:42:54 -0600
> Grant Likely <grant.likely@secretlab.ca> wrote:
>
>> On Tue, Jun 29, 2010 at 9:03 AM, Andres Salomon <dilinger@queued.net>
>> wrote:
> [...]
>>
>> >  Sparc and OLPC have very similar
>> > mechanisms for getting device tree info from OFW, so it makes sense
>> > to share code between them.
>>
>> Other than the flattened tree step; is the powerpc method dissimilar
>> from the Sparc and OLPC method for talking to OFW?  (This is not a
>> rhetorical question, I'm want to know if I'm missing some details).
>> The main difference I know about is that OFW can still kept alive at
>> runtime for sparc, which powerpc does not do.  However, keeping OFW
>> callable is a separate issue from how to extract the device tree.
>>
>
> After having a look at powerpc's flatten_device_tree, I don't see any
> obvious reason why OLPC couldn't use this

Okay.

>(though it still strikes me
> as weird to go from prom->fdt->dt when the option of prom->dt is
> available and less complex).

Which is why I didn't simply NACK it out of hand.  It is a valid point.

I'd probably be happier if both fdt and pdt used a shared set of
utility functions for allocating and tying together the device_node
data structures.  Then at least there would be only one instance of
code to deal with the fiddly data structure interconnections.

The nice thing about the powerpc version is that the tree can be
extracted really early in the boot process, before any of the core
kernel infrastructure or memory management is initialized.

> Do you already have the patches that put
> this into drivers/of/?

No.

g.
David Miller - July 6, 2010, 2:22 a.m.
From: Andres Salomon <dilinger@queued.net>
Date: Wed, 7 Jul 2010 04:07:34 +0000

>  - For the pdt, calling into the prom once for each property/node to
>    create a fdt, and then unflattening it.  This is better than the
>    previous option, but I don't think the prom->fdt code will be very
>    nice.

I'll need this on sparc64 at some point to support kexec() anyways.

So at least for sparc you can assume that a something-->fdt translator
is going to exist at some point in the future regardless of what
happens here.

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Grant Likely - July 6, 2010, 7 a.m.
On Mon, Jul 5, 2010 at 8:22 PM, David Miller <davem@davemloft.net> wrote:
> From: Andres Salomon <dilinger@queued.net>
> Date: Wed, 7 Jul 2010 04:07:34 +0000
>
>>  - For the pdt, calling into the prom once for each property/node to
>>    create a fdt, and then unflattening it.  This is better than the
>>    previous option, but I don't think the prom->fdt code will be very
>>    nice.
>
> I'll need this on sparc64 at some point to support kexec() anyways.
>
> So at least for sparc you can assume that a something-->fdt translator
> is going to exist at some point in the future regardless of what
> happens here.

Hi David,

I'm curious... what are your plans here?  Will you be keeping OF alive
between kexec()?  Will the new kernel get the entire device tree from
fdt, or will it still be talking to OF?  How will the fdt fragments as
Andres described above fit into sparc kexec (as opposed to generating
one big tree as in his first option)?

Cheers,
g.
David Miller - July 6, 2010, 7:16 a.m.
From: Grant Likely <grant.likely@secretlab.ca>
Date: Tue, 6 Jul 2010 01:00:06 -0600

> I'm curious... what are your plans here?  Will you be keeping OF alive
> between kexec()?  Will the new kernel get the entire device tree from
> fdt, or will it still be talking to OF?  How will the fdt fragments as
> Andres described above fit into sparc kexec (as opposed to generating
> one big tree as in his first option)?

On certain sparc64 systems, I have to stop making PROM calls early
in the boot right after I fetch the device tree into the kernel.

So yes for a kexec() I'll have to pass an fdt or similar to the
child kernel.

It could be a big linear fdt buffer, or fragments, it really doesn't
matter all that much actually.
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Grant Likely - July 6, 2010, 8:17 a.m.
On Tue, Jul 6, 2010 at 1:16 AM, David Miller <davem@davemloft.net> wrote:
> From: Grant Likely <grant.likely@secretlab.ca>
> Date: Tue, 6 Jul 2010 01:00:06 -0600
>
>> I'm curious... what are your plans here?  Will you be keeping OF alive
>> between kexec()?  Will the new kernel get the entire device tree from
>> fdt, or will it still be talking to OF?  How will the fdt fragments as
>> Andres described above fit into sparc kexec (as opposed to generating
>> one big tree as in his first option)?
>
> On certain sparc64 systems, I have to stop making PROM calls early
> in the boot right after I fetch the device tree into the kernel.
>
> So yes for a kexec() I'll have to pass an fdt or similar to the
> child kernel.
>
> It could be a big linear fdt buffer, or fragments, it really doesn't
> matter all that much actually.

Okay.  There is already support for getting the tree out of the kernel
and into fdt form via procfs.  Userspace can also modify it before
sending it back to kexec().  This will be easy no matter which
approach Andres uses.

g.
Grant Likely - July 6, 2010, 8:17 a.m.
On Tue, Jul 6, 2010 at 10:07 PM, Andres Salomon <dilinger@queued.net> wrote:
> On Wed, 30 Jun 2010 15:52:51 -0600
> Grant Likely <grant.likely@secretlab.ca> wrote:
>  - For the pdt, calling into the prom twice for each property/node,
>   getting the size of everything during the first tree traversal,
>   allocating memory, and then creating the tree during the second
>   traversal. This is slow and I don't see much point to it.
>
>  - For the pdt, calling into the prom once for each property/node to
>   create a fdt, and then unflattening it.  This is better than the
>   previous option, but I don't think the prom->fdt code will be very
>   nice.

No, don't do this.  It will be ugly.

>  - Changing the fdt code to allocate memory more dynamically; rather
>   than a first run through the fdt to determine the unflattened tree
>   size, simply allocate memory chunks as we run through the tree.
>   Memory might still be backed the same way (calling
>   early_init_dt_alloc_memory_arch to grab a chunk of memory, and then
>   allocating chunks of it via unflatten_dt_alloc), but the difference
>   would be that it wouldn't necessarily be contiguous, and in how it's
>   done.  For example, early_init_dt_alloc_memory_arch might be called
>   initially to allocate a 16k chunk, and once unflatten_dt_alloc runs
>   out of memory in that chunk, another 16k chunk might be allocated.
>   This would also translate to sparc's prom_early_alloc being used to
>   allocate the chunk, and then node/property structs being
>   allocated from those chunks.  (The 16k choice
>   is completely arbitrary; people more familiar w/ the early memory
>   setup of ppc/sparc might have a better suggestion)

I'm fine with option 3, but it is more complicated and the code for
option 1 already exists.  In fact, option 1 is almost of a
pre-requisite for doing option 3.  It makes sense to get the
double-pass method factored out of powerpc and working before
attempting the performance enhancement of option 3.

Note however, the fdt data format parser expects a single contiguous
region.  You'll want to copy it into a single region before parsing
it.

That Being Said....

I just finished talking with Ben about the parser code.  There is no
immediate imperative to generalizing the powerpc OF->fdt->unflatten
code (unless David decides it makes sense for sparc too), and the
possibility of an ARM machine using it is theoretical enough that I'm
just not going to waste cycles thinking about it.  If the situation
changes in a couple of year or two, then it can be refactored.

That clears the way for your original pdt patch.  It will need to be
respun for Stephen's CONFIG_OF changes, and I have some other
comments, but I'll reply to the patches directly for those.

Cheers,
g.
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Grant Likely - July 6, 2010, 9:21 a.m.
On Mon, Jun 28, 2010 at 8:00 PM, Andres Salomon <dilinger@queued.net> wrote:
>
> Stick code into drivers/of/pdt.c (Prom Device Tree) that other
> architectures with OpenFirmware resident in memory can make use of.
>
> Signed-off-by: Andres Salomon <dilinger@queued.net>

Some more comments below...

BTW, for the changes, you might what to split this patch into two
pieces.  One to verbatim copy the code from prom_common.c, and a
second to adapt it for non-sparc.  That will make the changes obvious
to future readers.  It will also make review easier.

> ---
>  arch/sparc/Kconfig              |    1 +
>  arch/sparc/include/asm/prom.h   |   15 +++-
>  arch/sparc/kernel/prom.h        |   14 ---
>  arch/sparc/kernel/prom_common.c |  173 +------------------------------
>  drivers/of/Kconfig              |    4 +
>  drivers/of/Makefile             |    1 +
>  drivers/of/pdt.c                |  225 +++++++++++++++++++++++++++++++++++++++
>  include/linux/of_pdt.h          |   37 +++++++
>  8 files changed, 282 insertions(+), 188 deletions(-)
>  create mode 100644 drivers/of/pdt.c
>  create mode 100644 include/linux/of_pdt.h
>
> diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
> index 6f1470b..b4cb63b 100644
> --- a/arch/sparc/Kconfig
> +++ b/arch/sparc/Kconfig
> @@ -150,6 +150,7 @@ config ARCH_NO_VIRT_TO_BUS
>
>  config OF
>        def_bool y
> +       select OF_PROMTREE
>
>  config ARCH_SUPPORTS_DEBUG_PAGEALLOC
>        def_bool y if SPARC64
> diff --git a/arch/sparc/include/asm/prom.h b/arch/sparc/include/asm/prom.h
> index f845828..0834c2a 100644
> --- a/arch/sparc/include/asm/prom.h
> +++ b/arch/sparc/include/asm/prom.h
> @@ -18,6 +18,7 @@
>  * 2 of the License, or (at your option) any later version.
>  */
>  #include <linux/types.h>
> +#include <linux/of_pdt.h>
>  #include <linux/proc_fs.h>
>  #include <linux/mutex.h>
>  #include <asm/atomic.h>
> @@ -65,8 +66,18 @@ extern struct device_node *of_console_device;
>  extern char *of_console_path;
>  extern char *of_console_options;
>
> -extern void (*prom_build_more)(struct device_node *dp, struct device_node ***nextp);
> -extern char *build_full_name(struct device_node *dp);
> +/* stuff used by of/pdt */
> +extern void * prom_early_alloc(unsigned long size);
> +extern void irq_trans_init(struct device_node *dp);
> +extern char *build_path_component(struct device_node *dp);
> +
> +extern char *prom_firstprop(int node, char *buffer);
> +extern char *prom_nextprop(int node, const char *oprop, char *buffer);
> +extern int prom_getproplen(int node, const char *prop);
> +extern int prom_getproperty(int node, const char *prop,
> +                           char *buffer, int bufsize);
> +extern int prom_getchild(int node);
> +extern int prom_getsibling(int node);

These become the API required by of/pdt.  They should be defined in a
arch-independent header file.  Something like include/linux/of_pdt.h

Right now only OLPC will be using this, so static function definitions
are just fine.  However, if there is ever more than one method for
talking to OFW, then these hooks will need to be converted into an ops
structure so the right one can be passed in at runtime.

> diff --git a/drivers/of/pdt.c b/drivers/of/pdt.c
> new file mode 100644
> index 0000000..b24167f
> --- /dev/null
> +++ b/drivers/of/pdt.c
> @@ -0,0 +1,225 @@
> +/*
> + * Paul Mackerras      August 1996.
> + * Copyright (C) 1996-2005 Paul Mackerras.
> + *
> + *  Adapted for 64bit PowerPC by Dave Engebretsen and Peter Bergner.
> + *    {engebret|bergner}@us.ibm.com
> + *
> + *  Adapted for sparc by David S. Miller davem@davemloft.net
> + *  Adapted for multiple architectures by Andres Salomon <dilinger@queued.net>
> + *
> + *      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/module.h>
> +#include <linux/errno.h>
> +#include <linux/mutex.h>
> +#include <linux/slab.h>
> +#include <linux/of.h>
> +#include <linux/of_pdt.h>
> +#include <asm/prom.h>
> +
> +/* TODO: mark this stuff as __initdata */
> +void (*prom_build_more)(struct device_node *dp, struct device_node ***nextp);

So do it.  :-)

> +
> +#if defined(CONFIG_SPARC)
> +static unsigned int prom_unique_id;
> +
> +#define inc_unique_id(p) do { \
> +       (p)->unique_id = prom_unique_id++; \
> +} while (0)
> +
> +static inline const char *fetch_node_name(struct device_node *dp)
> +{
> +       return dp->path_component_name;
> +}
> +
> +#else
> +
> +#define inc_unique_id(p)       do { } while(0)

Use an empty static inline instead.

> +
> +static inline const char *fetch_node_name(struct device_node *dp)
> +{
> +       return dp->name;
> +}
> +
> +static inline void irq_trans_init(struct device_node *dp)
> +{
> +       /* unused on non-SPARC architectures */
> +}
> +
> +#endif /* !CONFIG_SPARC */
> +
> +static struct property * __init build_one_prop(phandle node, char *prev,
> +                                              char *special_name,
> +                                              void *special_val,
> +                                              int special_len)

I'd like to see all the static symbols in this file prefixed with
something unique to avoid collisions with the global namespace.
of_pdt_* would be good.  I'm doing this with the other files in
drivers/of whenever I can too.

> +{
> +       static struct property *tmp = NULL;
> +       struct property *p;
> +       const char *name;
> +
> +       if (tmp) {
> +               p = tmp;
> +               memset(p, 0, sizeof(*p) + 32);
> +               tmp = NULL;
> +       } else {
> +               p = prom_early_alloc(sizeof(struct property) + 32);
> +               inc_unique_id(p);
> +       }
> +
> +       p->name = (char *) (p + 1);
> +       if (special_name) {
> +               strcpy(p->name, special_name);
> +               p->length = special_len;
> +               p->value = prom_early_alloc(special_len);
> +               memcpy(p->value, special_val, special_len);
> +       } else {
> +               if (prev == NULL) {
> +                       name = prom_firstprop(node, p->name);
> +               } else {
> +                       name = prom_nextprop(node, prev, p->name);
> +               }
> +
> +               if (!name || strlen(name) == 0) {
> +                       tmp = p;
> +                       return NULL;
> +               }
> +#ifdef CONFIG_SPARC32
> +               strcpy(p->name, name);
> +#endif
> +               p->length = prom_getproplen(node, p->name);
> +               if (p->length <= 0) {
> +                       p->length = 0;
> +               } else {
> +                       int len;
> +
> +                       p->value = prom_early_alloc(p->length + 1);
> +                       len = prom_getproperty(node, p->name, p->value,
> +                                              p->length);
> +                       if (len <= 0)
> +                               p->length = 0;
> +                       ((unsigned char *)p->value)[p->length] = '\0';
> +               }
> +       }
> +       return p;
> +}
> +
> +static struct property * __init build_prop_list(phandle node)
> +{
> +       struct property *head, *tail;
> +
> +       head = tail = build_one_prop(node, NULL,
> +                                    ".node", &node, sizeof(node));
> +
> +       tail->next = build_one_prop(node, NULL, NULL, NULL, 0);
> +       tail = tail->next;
> +       while(tail) {
> +               tail->next = build_one_prop(node, tail->name,
> +                                           NULL, NULL, 0);
> +               tail = tail->next;
> +       }
> +
> +       return head;
> +}
> +
> +static char * __init get_one_property(phandle node, const char *name)
> +{
> +       char *buf = "<NULL>";
> +       int len;
> +
> +       len = prom_getproplen(node, name);
> +       if (len > 0) {
> +               buf = prom_early_alloc(len);
> +               len = prom_getproperty(node, name, buf, len);
> +       }
> +
> +       return buf;
> +}
> +
> +struct device_node * __init prom_create_node(phandle node,
> +                                            struct device_node *parent)
> +{
> +       struct device_node *dp;
> +
> +       if (!node)
> +               return NULL;
> +
> +       dp = prom_early_alloc(sizeof(*dp));
> +       inc_unique_id(dp);
> +       dp->parent = parent;
> +
> +       kref_init(&dp->kref);
> +
> +       dp->name = get_one_property(node, "name");
> +       dp->type = get_one_property(node, "device_type");
> +       dp->phandle = node;
> +
> +       dp->properties = build_prop_list(node);
> +
> +       irq_trans_init(dp);
> +
> +       return dp;
> +}
> +
> +static char * __init build_full_name(struct device_node *dp)
> +{
> +       int len, ourlen, plen;
> +       char *n;
> +
> +       plen = strlen(dp->parent->full_name);
> +       ourlen = strlen(fetch_node_name(dp));
> +       len = ourlen + plen + 2;
> +
> +       n = prom_early_alloc(len);
> +       strcpy(n, dp->parent->full_name);
> +       if (!is_root_node(dp->parent)) {
> +               strcpy(n + plen, "/");
> +               plen++;
> +       }
> +       strcpy(n + plen, fetch_node_name(dp));
> +
> +       return n;
> +}
> +
> +struct device_node * __init prom_build_tree(struct device_node *parent,
> +                                           phandle node,
> +                                           struct device_node ***nextp)
> +{
> +       struct device_node *ret = NULL, *prev_sibling = NULL;
> +       struct device_node *dp;
> +
> +       while (1) {
> +               dp = prom_create_node(node, parent);
> +               if (!dp)
> +                       break;
> +
> +               if (prev_sibling)
> +                       prev_sibling->sibling = dp;
> +
> +               if (!ret)
> +                       ret = dp;
> +               prev_sibling = dp;
> +
> +               *(*nextp) = dp;
> +               *nextp = &dp->allnext;
> +
> +#if defined(CONFIG_SPARC)
> +               dp->path_component_name = build_path_component(dp);
> +#endif
> +               dp->full_name = build_full_name(dp);
> +
> +               dp->child = prom_build_tree(dp, prom_getchild(node), nextp);
> +
> +               if (prom_build_more)
> +                       prom_build_more(dp, nextp);
> +
> +               node = prom_getsibling(node);
> +       }
> +
> +       return ret;
> +}

prom_build_devicetree() should also be factored out.

> diff --git a/include/linux/of_pdt.h b/include/linux/of_pdt.h
> new file mode 100644
> index 0000000..f62616e
> --- /dev/null
> +++ b/include/linux/of_pdt.h
> @@ -0,0 +1,37 @@
> +#include <linux/of.h>  /* linux/of.h gets to determine #include ordering */

Do you really need this #include in this way?  Can it be moved inside
the #ifndef OF_PDT block below?

> +/*
> + * Definitions for building a device tree by calling into the
> + * Open Firmware PROM.
> + *
> + * Copyright (C) 1996-2005 Paul Mackerras.
> + * Copyright (C) 2010  Andres Salomon <dilinger@queued.net>
> + *
> + * Updates for PPC64 by Peter Bergner & David Engebretsen, IBM Corp.
> + * Updates for SPARC by David S. Miller
> + *
> + * 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 _LINUX_OF_PDT_H
> +#define _LINUX_OF_PDT_H
> +
> +extern struct device_node *prom_create_node(phandle node,
> +                                           struct device_node *parent);
> +extern struct device_node *prom_build_tree(struct device_node *parent,
> +                                          phandle node,
> +                                          struct device_node ***nextp);
> +
> +extern void (*prom_build_more)(struct device_node *dp, struct device_node ***nextp);
> +
> +static inline int is_root_node(const struct device_node *dp)
> +{
> +       if (!dp)
> +               return 0;
> +
> +       return (dp->parent == NULL);
> +}

This doesn't look like a pdt specific function, it could go in
include/linux/of.h.

Another general comment, I'm still not thrilled with this code having
its own independent method for building the tree, but I doubt the
existing add/remove nodes and properties code is usable early enough
to be suitable for sparc.  How early do you extract the device tree on
OLPC?  How are you going to use the data?

Anyway, enough comments for tonight.  I'll may have more on then next
round.  Time to go to bed.

g.
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Benjamin Herrenschmidt - July 6, 2010, 10:17 a.m.
> Sounds like we have a winner.  I'll concentrate on that, thanks for
> the heads up.

Note that the conversion from OF -> fdt that powerpc does is a bit
"special". The code isn't quite a "wrapper" but almost. It shared pretty
much no symbols or variables with the rest of the kernel.

There are various reasons for that. It has to run -very- early, in fact,
before we do anything else at boot time, since we run off OF existing
environment (stack etc...) at at whatever address the kernel is loaded,
ie. before we relocate it down to 0.

To deal with that, we use compile/linker tricks to generate
pseudo-relocatable code (with limitations) and funny macros when
accessing global symbols.

In addition, we have various workarounds for powerpc specific
implementation issues (OF bugs, but also instanciating the IOMMU tables
on Power4, starting secondary CPUs and parking them in a wait loop,
etc...).

Thus I'm not sure there's that much benefit in trying to make that code
common with other archs, and possibly a lot of pain involved.

Cheers,
Ben.
 

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Andres Salomon - July 6, 2010, 9:54 p.m.
On Tue, 6 Jul 2010 03:21:21 -0600
Grant Likely <grant.likely@secretlab.ca> wrote:

> On Mon, Jun 28, 2010 at 8:00 PM, Andres Salomon <dilinger@queued.net>
> wrote:
> >
> > Stick code into drivers/of/pdt.c (Prom Device Tree) that other
> > architectures with OpenFirmware resident in memory can make use of.
> >
> > Signed-off-by: Andres Salomon <dilinger@queued.net>
> 
> Some more comments below...
> 

Thanks for the review!



> >  arch/sparc/Kconfig              |    1 +
> >  arch/sparc/include/asm/prom.h   |   15 +++-
> >  arch/sparc/kernel/prom.h        |   14 ---
> >  arch/sparc/kernel/prom_common.c |  173
> > +------------------------------ drivers/of/Kconfig              |
> >  4 + drivers/of/Makefile             |    1 +
> >  drivers/of/pdt.c                |  225
> > +++++++++++++++++++++++++++++++++++++++ include/linux/of_pdt.h
> >      |   37 +++++++ 8 files changed, 282 insertions(+), 188
> > deletions(-) create mode 100644 drivers/of/pdt.c
> >  create mode 100644 include/linux/of_pdt.h
> >
> > diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
> > index 6f1470b..b4cb63b 100644
> > --- a/arch/sparc/Kconfig
> > +++ b/arch/sparc/Kconfig
> > @@ -150,6 +150,7 @@ config ARCH_NO_VIRT_TO_BUS
> >
> >  config OF
> >        def_bool y
> > +       select OF_PROMTREE
> >
> >  config ARCH_SUPPORTS_DEBUG_PAGEALLOC
> >        def_bool y if SPARC64
> > diff --git a/arch/sparc/include/asm/prom.h
> > b/arch/sparc/include/asm/prom.h index f845828..0834c2a 100644
> > --- a/arch/sparc/include/asm/prom.h
> > +++ b/arch/sparc/include/asm/prom.h
> > @@ -18,6 +18,7 @@
> >  * 2 of the License, or (at your option) any later version.
> >  */
> >  #include <linux/types.h>
> > +#include <linux/of_pdt.h>
> >  #include <linux/proc_fs.h>
> >  #include <linux/mutex.h>
> >  #include <asm/atomic.h>
> > @@ -65,8 +66,18 @@ extern struct device_node *of_console_device;
> >  extern char *of_console_path;
> >  extern char *of_console_options;
> >
> > -extern void (*prom_build_more)(struct device_node *dp, struct
> > device_node ***nextp); -extern char *build_full_name(struct
> > device_node *dp); +/* stuff used by of/pdt */
> > +extern void * prom_early_alloc(unsigned long size);
> > +extern void irq_trans_init(struct device_node *dp);
> > +extern char *build_path_component(struct device_node *dp);
> > +
> > +extern char *prom_firstprop(int node, char *buffer);
> > +extern char *prom_nextprop(int node, const char *oprop, char
> > *buffer); +extern int prom_getproplen(int node, const char *prop);
> > +extern int prom_getproperty(int node, const char *prop,
> > +                           char *buffer, int bufsize);
> > +extern int prom_getchild(int node);
> > +extern int prom_getsibling(int node);
> 
> These become the API required by of/pdt.  They should be defined in a
> arch-independent header file.  Something like include/linux/of_pdt.h
> 
> Right now only OLPC will be using this, so static function definitions
> are just fine.  However, if there is ever more than one method for
> talking to OFW, then these hooks will need to be converted into an ops
> structure so the right one can be passed in at runtime.
> 

Note that sparc and OLPC actually use slightly different function
signatures; OLPC uses phandles for nodes, while sparc uses ints.  Not a
huge difference, but enough that I didn't want to mess w/ a generic
version of it early in the process.  I agree that op structs would be
nicer, and will probably move towards that. 

[...]

> > diff --git a/include/linux/of_pdt.h b/include/linux/of_pdt.h
> > new file mode 100644
> > index 0000000..f62616e
> > --- /dev/null
> > +++ b/include/linux/of_pdt.h
> > @@ -0,0 +1,37 @@
> > +#include <linux/of.h>  /* linux/of.h gets to determine #include
> > ordering */
> 
> Do you really need this #include in this way?  Can it be moved inside
> the #ifndef OF_PDT block below?
> 

Not sure, will try out different variants and see what breaks.

[...]

> Another general comment, I'm still not thrilled with this code having
> its own independent method for building the tree, but I doubt the
> existing add/remove nodes and properties code is usable early enough
> to be suitable for sparc.  How early do you extract the device tree on
> OLPC?  How are you going to use the data?

Not that early; very early code fetches information necessary to call
into the PROM, and ensures that the kernel doesn't clobber OFW's
memory.   After that, we can build the dt at any point during init.
The data is to be exported via proc for userspace to use in
determining hardware (and firmware) info.

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Grant Likely - July 6, 2010, 10:06 p.m.
On Tue, Jul 6, 2010 at 3:54 PM, Andres Salomon <dilinger@queued.net> wrote:
> On Tue, 6 Jul 2010 03:21:21 -0600
> Grant Likely <grant.likely@secretlab.ca> wrote:
>
>> On Mon, Jun 28, 2010 at 8:00 PM, Andres Salomon <dilinger@queued.net>
>> wrote:
>> >
>> > Stick code into drivers/of/pdt.c (Prom Device Tree) that other
>> > architectures with OpenFirmware resident in memory can make use of.
>> >
>> > Signed-off-by: Andres Salomon <dilinger@queued.net>
>>
>> Some more comments below...
>>
>
> Thanks for the review!
>
>
>
>> >  arch/sparc/Kconfig              |    1 +
>> >  arch/sparc/include/asm/prom.h   |   15 +++-
>> >  arch/sparc/kernel/prom.h        |   14 ---
>> >  arch/sparc/kernel/prom_common.c |  173
>> > +------------------------------ drivers/of/Kconfig              |
>> >  4 + drivers/of/Makefile             |    1 +
>> >  drivers/of/pdt.c                |  225
>> > +++++++++++++++++++++++++++++++++++++++ include/linux/of_pdt.h
>> >      |   37 +++++++ 8 files changed, 282 insertions(+), 188
>> > deletions(-) create mode 100644 drivers/of/pdt.c
>> >  create mode 100644 include/linux/of_pdt.h
>> >
>> > diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
>> > index 6f1470b..b4cb63b 100644
>> > --- a/arch/sparc/Kconfig
>> > +++ b/arch/sparc/Kconfig
>> > @@ -150,6 +150,7 @@ config ARCH_NO_VIRT_TO_BUS
>> >
>> >  config OF
>> >        def_bool y
>> > +       select OF_PROMTREE
>> >
>> >  config ARCH_SUPPORTS_DEBUG_PAGEALLOC
>> >        def_bool y if SPARC64
>> > diff --git a/arch/sparc/include/asm/prom.h
>> > b/arch/sparc/include/asm/prom.h index f845828..0834c2a 100644
>> > --- a/arch/sparc/include/asm/prom.h
>> > +++ b/arch/sparc/include/asm/prom.h
>> > @@ -18,6 +18,7 @@
>> >  * 2 of the License, or (at your option) any later version.
>> >  */
>> >  #include <linux/types.h>
>> > +#include <linux/of_pdt.h>
>> >  #include <linux/proc_fs.h>
>> >  #include <linux/mutex.h>
>> >  #include <asm/atomic.h>
>> > @@ -65,8 +66,18 @@ extern struct device_node *of_console_device;
>> >  extern char *of_console_path;
>> >  extern char *of_console_options;
>> >
>> > -extern void (*prom_build_more)(struct device_node *dp, struct
>> > device_node ***nextp); -extern char *build_full_name(struct
>> > device_node *dp); +/* stuff used by of/pdt */
>> > +extern void * prom_early_alloc(unsigned long size);
>> > +extern void irq_trans_init(struct device_node *dp);
>> > +extern char *build_path_component(struct device_node *dp);
>> > +
>> > +extern char *prom_firstprop(int node, char *buffer);
>> > +extern char *prom_nextprop(int node, const char *oprop, char
>> > *buffer); +extern int prom_getproplen(int node, const char *prop);
>> > +extern int prom_getproperty(int node, const char *prop,
>> > +                           char *buffer, int bufsize);
>> > +extern int prom_getchild(int node);
>> > +extern int prom_getsibling(int node);
>>
>> These become the API required by of/pdt.  They should be defined in a
>> arch-independent header file.  Something like include/linux/of_pdt.h
>>
>> Right now only OLPC will be using this, so static function definitions
>> are just fine.  However, if there is ever more than one method for
>> talking to OFW, then these hooks will need to be converted into an ops
>> structure so the right one can be passed in at runtime.
>>
>
> Note that sparc and OLPC actually use slightly different function
> signatures; OLPC uses phandles for nodes, while sparc uses ints.  Not a
> huge difference, but enough that I didn't want to mess w/ a generic
> version of it early in the process.

phandle is simply defined as a u32.  It probably wouldn't be difficult
to change the sparc code to use phandle; redefining the type for sparc
if need be.

>  I agree that op structs would be
> nicer, and will probably move towards that.
>
> [...]
>
>> > diff --git a/include/linux/of_pdt.h b/include/linux/of_pdt.h
>> > new file mode 100644
>> > index 0000000..f62616e
>> > --- /dev/null
>> > +++ b/include/linux/of_pdt.h
>> > @@ -0,0 +1,37 @@
>> > +#include <linux/of.h>  /* linux/of.h gets to determine #include
>> > ordering */
>>
>> Do you really need this #include in this way?  Can it be moved inside
>> the #ifndef OF_PDT block below?
>>
>
> Not sure, will try out different variants and see what breaks.
>
> [...]
>
>> Another general comment, I'm still not thrilled with this code having
>> its own independent method for building the tree, but I doubt the
>> existing add/remove nodes and properties code is usable early enough
>> to be suitable for sparc.  How early do you extract the device tree on
>> OLPC?  How are you going to use the data?
>
> Not that early; very early code fetches information necessary to call
> into the PROM, and ensures that the kernel doesn't clobber OFW's
> memory.   After that, we can build the dt at any point during init.
> The data is to be exported via proc for userspace to use in
> determining hardware (and firmware) info.

Okay, so it is only the userspace interface that you're interested in,
correct?  You have no needs/plans (as of yet) to register devices out
of the device tree?

g.
Andres Salomon - July 7, 2010, 1:15 a.m.
On Tue, 6 Jul 2010 16:06:54 -0600
Grant Likely <grant.likely@secretlab.ca> wrote:
[...] 
> Okay, so it is only the userspace interface that you're interested in,
> correct?  You have no needs/plans (as of yet) to register devices out
> of the device tree?
> 

Correct.

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Andres Salomon - July 7, 2010, 4:07 a.m.
On Wed, 30 Jun 2010 15:52:51 -0600
Grant Likely <grant.likely@secretlab.ca> wrote:

> On Tue, Jun 29, 2010 at 5:36 PM, Andres Salomon <dilinger@queued.net>
> wrote:
> > On Tue, 29 Jun 2010 15:42:54 -0600
> > Grant Likely <grant.likely@secretlab.ca> wrote:
> >
> >> On Tue, Jun 29, 2010 at 9:03 AM, Andres Salomon
> >> <dilinger@queued.net> wrote:
> > [...]
> >>
> >> >  Sparc and OLPC have very similar
> >> > mechanisms for getting device tree info from OFW, so it makes
> >> > sense to share code between them.
> >>
> >> Other than the flattened tree step; is the powerpc method
> >> dissimilar from the Sparc and OLPC method for talking to OFW?
> >>  (This is not a rhetorical question, I'm want to know if I'm
> >> missing some details). The main difference I know about is that
> >> OFW can still kept alive at runtime for sparc, which powerpc does
> >> not do.  However, keeping OFW callable is a separate issue from
> >> how to extract the device tree.
> >>
> >
> > After having a look at powerpc's flatten_device_tree, I don't see
> > any obvious reason why OLPC couldn't use this
> 
> Okay.
> 
> >(though it still strikes me
> > as weird to go from prom->fdt->dt when the option of prom->dt is
> > available and less complex).
> 
> Which is why I didn't simply NACK it out of hand.  It is a valid
> point.
> 
> I'd probably be happier if both fdt and pdt used a shared set of
> utility functions for allocating and tying together the device_node
> data structures.  Then at least there would be only one instance of
> code to deal with the fiddly data structure interconnections.

The problem with unifying it is that both methods have different
assumptions; the fdt determines the size of the unflattened dt in
advance, and allocates a contiguous block of memory up front (the
memory block being smaller than the pdt memory usage because various
strings are already present in the fdt, so the unflattened tree simply
points at those strings).  The pdt, otoh, allocates more memory as the
tree is discovered (by calling into the prom).

Possible options include:

 - For the pdt, calling into the prom twice for each property/node,
   getting the size of everything during the first tree traversal,
   allocating memory, and then creating the tree during the second
   traversal. This is slow and I don't see much point to it.

 - For the pdt, calling into the prom once for each property/node to
   create a fdt, and then unflattening it.  This is better than the
   previous option, but I don't think the prom->fdt code will be very
   nice.

 - Changing the fdt code to allocate memory more dynamically; rather
   than a first run through the fdt to determine the unflattened tree
   size, simply allocate memory chunks as we run through the tree.
   Memory might still be backed the same way (calling
   early_init_dt_alloc_memory_arch to grab a chunk of memory, and then
   allocating chunks of it via unflatten_dt_alloc), but the difference
   would be that it wouldn't necessarily be contiguous, and in how it's
   done.  For example, early_init_dt_alloc_memory_arch might be called
   initially to allocate a 16k chunk, and once unflatten_dt_alloc runs
   out of memory in that chunk, another 16k chunk might be allocated.
   This would also translate to sparc's prom_early_alloc being used to
   allocate the chunk, and then node/property structs being
   allocated from those chunks.  (The 16k choice
   is completely arbitrary; people more familiar w/ the early memory
   setup of ppc/sparc might have a better suggestion)

That last option is what I think makes the most sense; however, are
there technical reasons (other than how unflatten_device_tree is
written) that the unflattened dt must be in a contiguous memory
region?  The chunk allocation code would be backed by things like
__alloc_bootmem and lmb_alloc, and the dt_alloc code would be new code
that simply tracks the amount remaining in a list of chunks, and
allocates a new chunk if necessary.


> 
> The nice thing about the powerpc version is that the tree can be
> extracted really early in the boot process, before any of the core
> kernel infrastructure or memory management is initialized.
> 
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Andres Salomon - July 7, 2010, 5:15 a.m.
On Mon, 05 Jul 2010 19:22:21 -0700 (PDT)
David Miller <davem@davemloft.net> wrote:

> From: Andres Salomon <dilinger@queued.net>
> Date: Wed, 7 Jul 2010 04:07:34 +0000
> 
> >  - For the pdt, calling into the prom once for each property/node to
> >    create a fdt, and then unflattening it.  This is better than the
> >    previous option, but I don't think the prom->fdt code will be
> > very nice.
> 
> I'll need this on sparc64 at some point to support kexec() anyways.
> 
> So at least for sparc you can assume that a something-->fdt translator
> is going to exist at some point in the future regardless of what
> happens here.
> 


Sounds like we have a winner.  I'll concentrate on that, thanks for
the heads up.
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Patch

diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 6f1470b..b4cb63b 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -150,6 +150,7 @@  config ARCH_NO_VIRT_TO_BUS
 
 config OF
 	def_bool y
+	select OF_PROMTREE
 
 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
 	def_bool y if SPARC64
diff --git a/arch/sparc/include/asm/prom.h b/arch/sparc/include/asm/prom.h
index f845828..0834c2a 100644
--- a/arch/sparc/include/asm/prom.h
+++ b/arch/sparc/include/asm/prom.h
@@ -18,6 +18,7 @@ 
  * 2 of the License, or (at your option) any later version.
  */
 #include <linux/types.h>
+#include <linux/of_pdt.h>
 #include <linux/proc_fs.h>
 #include <linux/mutex.h>
 #include <asm/atomic.h>
@@ -65,8 +66,18 @@  extern struct device_node *of_console_device;
 extern char *of_console_path;
 extern char *of_console_options;
 
-extern void (*prom_build_more)(struct device_node *dp, struct device_node ***nextp);
-extern char *build_full_name(struct device_node *dp);
+/* stuff used by of/pdt */
+extern void * prom_early_alloc(unsigned long size);
+extern void irq_trans_init(struct device_node *dp);
+extern char *build_path_component(struct device_node *dp);
+
+extern char *prom_firstprop(int node, char *buffer);
+extern char *prom_nextprop(int node, const char *oprop, char *buffer);
+extern int prom_getproplen(int node, const char *prop);
+extern int prom_getproperty(int node, const char *prop,
+			    char *buffer, int bufsize);
+extern int prom_getchild(int node);
+extern int prom_getsibling(int node);
 
 #endif /* __KERNEL__ */
 #endif /* _SPARC_PROM_H */
diff --git a/arch/sparc/kernel/prom.h b/arch/sparc/kernel/prom.h
index a8591ef..cf5fe1c 100644
--- a/arch/sparc/kernel/prom.h
+++ b/arch/sparc/kernel/prom.h
@@ -4,20 +4,6 @@ 
 #include <linux/spinlock.h>
 #include <asm/prom.h>
 
-extern void * prom_early_alloc(unsigned long size);
-extern void irq_trans_init(struct device_node *dp);
-
-extern unsigned int prom_unique_id;
-
-static inline int is_root_node(const struct device_node *dp)
-{
-	if (!dp)
-		return 0;
-
-	return (dp->parent == NULL);
-}
-
-extern char *build_path_component(struct device_node *dp);
 extern void of_console_init(void);
 
 extern unsigned int prom_early_allocated;
diff --git a/arch/sparc/kernel/prom_common.c b/arch/sparc/kernel/prom_common.c
index 57ac9e2..fc990e1 100644
--- a/arch/sparc/kernel/prom_common.c
+++ b/arch/sparc/kernel/prom_common.c
@@ -20,14 +20,13 @@ 
 #include <linux/mutex.h>
 #include <linux/slab.h>
 #include <linux/of.h>
+#include <linux/of_pdt.h>
 #include <asm/prom.h>
 #include <asm/oplib.h>
 #include <asm/leon.h>
 
 #include "prom.h"
 
-void (*prom_build_more)(struct device_node *dp, struct device_node ***nextp);
-
 struct device_node *of_console_device;
 EXPORT_SYMBOL(of_console_device);
 
@@ -119,176 +118,6 @@  int of_find_in_proplist(const char *list, const char *match, int len)
 }
 EXPORT_SYMBOL(of_find_in_proplist);
 
-unsigned int prom_unique_id;
-
-static struct property * __init build_one_prop(phandle node, char *prev,
-					       char *special_name,
-					       void *special_val,
-					       int special_len)
-{
-	static struct property *tmp = NULL;
-	struct property *p;
-	const char *name;
-
-	if (tmp) {
-		p = tmp;
-		memset(p, 0, sizeof(*p) + 32);
-		tmp = NULL;
-	} else {
-		p = prom_early_alloc(sizeof(struct property) + 32);
-		p->unique_id = prom_unique_id++;
-	}
-
-	p->name = (char *) (p + 1);
-	if (special_name) {
-		strcpy(p->name, special_name);
-		p->length = special_len;
-		p->value = prom_early_alloc(special_len);
-		memcpy(p->value, special_val, special_len);
-	} else {
-		if (prev == NULL) {
-			name = prom_firstprop(node, p->name);
-		} else {
-			name = prom_nextprop(node, prev, p->name);
-		}
-
-		if (!name || strlen(name) == 0) {
-			tmp = p;
-			return NULL;
-		}
-#ifdef CONFIG_SPARC32
-		strcpy(p->name, name);
-#endif
-		p->length = prom_getproplen(node, p->name);
-		if (p->length <= 0) {
-			p->length = 0;
-		} else {
-			int len;
-
-			p->value = prom_early_alloc(p->length + 1);
-			len = prom_getproperty(node, p->name, p->value,
-					       p->length);
-			if (len <= 0)
-				p->length = 0;
-			((unsigned char *)p->value)[p->length] = '\0';
-		}
-	}
-	return p;
-}
-
-static struct property * __init build_prop_list(phandle node)
-{
-	struct property *head, *tail;
-
-	head = tail = build_one_prop(node, NULL,
-				     ".node", &node, sizeof(node));
-
-	tail->next = build_one_prop(node, NULL, NULL, NULL, 0);
-	tail = tail->next;
-	while(tail) {
-		tail->next = build_one_prop(node, tail->name,
-					    NULL, NULL, 0);
-		tail = tail->next;
-	}
-
-	return head;
-}
-
-static char * __init get_one_property(phandle node, const char *name)
-{
-	char *buf = "<NULL>";
-	int len;
-
-	len = prom_getproplen(node, name);
-	if (len > 0) {
-		buf = prom_early_alloc(len);
-		len = prom_getproperty(node, name, buf, len);
-	}
-
-	return buf;
-}
-
-static struct device_node * __init prom_create_node(phandle node,
-						    struct device_node *parent)
-{
-	struct device_node *dp;
-
-	if (!node)
-		return NULL;
-
-	dp = prom_early_alloc(sizeof(*dp));
-	dp->unique_id = prom_unique_id++;
-	dp->parent = parent;
-
-	kref_init(&dp->kref);
-
-	dp->name = get_one_property(node, "name");
-	dp->type = get_one_property(node, "device_type");
-	dp->phandle = node;
-
-	dp->properties = build_prop_list(node);
-
-	irq_trans_init(dp);
-
-	return dp;
-}
-
-char * __init build_full_name(struct device_node *dp)
-{
-	int len, ourlen, plen;
-	char *n;
-
-	plen = strlen(dp->parent->full_name);
-	ourlen = strlen(dp->path_component_name);
-	len = ourlen + plen + 2;
-
-	n = prom_early_alloc(len);
-	strcpy(n, dp->parent->full_name);
-	if (!is_root_node(dp->parent)) {
-		strcpy(n + plen, "/");
-		plen++;
-	}
-	strcpy(n + plen, dp->path_component_name);
-
-	return n;
-}
-
-static struct device_node * __init prom_build_tree(struct device_node *parent,
-						   phandle node,
-						   struct device_node ***nextp)
-{
-	struct device_node *ret = NULL, *prev_sibling = NULL;
-	struct device_node *dp;
-
-	while (1) {
-		dp = prom_create_node(node, parent);
-		if (!dp)
-			break;
-
-		if (prev_sibling)
-			prev_sibling->sibling = dp;
-
-		if (!ret)
-			ret = dp;
-		prev_sibling = dp;
-
-		*(*nextp) = dp;
-		*nextp = &dp->allnext;
-
-		dp->path_component_name = build_path_component(dp);
-		dp->full_name = build_full_name(dp);
-
-		dp->child = prom_build_tree(dp, prom_getchild(node), nextp);
-
-		if (prom_build_more)
-			prom_build_more(dp, nextp);
-
-		node = prom_getsibling(node);
-	}
-
-	return ret;
-}
-
 unsigned int prom_early_allocated __initdata;
 
 void __init prom_build_devicetree(void)
diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
index 7cecc8f..41921a8 100644
--- a/drivers/of/Kconfig
+++ b/drivers/of/Kconfig
@@ -2,6 +2,10 @@  config OF_FLATTREE
 	bool
 	depends on OF
 
+config OF_PROMTREE
+	bool
+	depends on OF
+
 config OF_DYNAMIC
 	def_bool y
 	depends on OF && PPC_OF
diff --git a/drivers/of/Makefile b/drivers/of/Makefile
index f232cc9..54e8517 100644
--- a/drivers/of/Makefile
+++ b/drivers/of/Makefile
@@ -1,5 +1,6 @@ 
 obj-y = base.o
 obj-$(CONFIG_OF_FLATTREE) += fdt.o
+obj-$(CONFIG_OF_PROMTREE) += pdt.o
 obj-$(CONFIG_OF_DEVICE) += device.o platform.o
 obj-$(CONFIG_OF_GPIO)   += gpio.o
 obj-$(CONFIG_OF_I2C)	+= of_i2c.o
diff --git a/drivers/of/pdt.c b/drivers/of/pdt.c
new file mode 100644
index 0000000..b24167f
--- /dev/null
+++ b/drivers/of/pdt.c
@@ -0,0 +1,225 @@ 
+/*
+ * Paul Mackerras	August 1996.
+ * Copyright (C) 1996-2005 Paul Mackerras.
+ *
+ *  Adapted for 64bit PowerPC by Dave Engebretsen and Peter Bergner.
+ *    {engebret|bergner}@us.ibm.com
+ *
+ *  Adapted for sparc by David S. Miller davem@davemloft.net
+ *  Adapted for multiple architectures by Andres Salomon <dilinger@queued.net>
+ *
+ *      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/module.h>
+#include <linux/errno.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/of_pdt.h>
+#include <asm/prom.h>
+
+/* TODO: mark this stuff as __initdata */
+void (*prom_build_more)(struct device_node *dp, struct device_node ***nextp);
+
+#if defined(CONFIG_SPARC)
+static unsigned int prom_unique_id;
+
+#define inc_unique_id(p) do { \
+	(p)->unique_id = prom_unique_id++; \
+} while (0)
+
+static inline const char *fetch_node_name(struct device_node *dp)
+{
+	return dp->path_component_name;
+}
+
+#else
+
+#define inc_unique_id(p)	do { } while(0)
+
+static inline const char *fetch_node_name(struct device_node *dp)
+{
+	return dp->name;
+}
+
+static inline void irq_trans_init(struct device_node *dp)
+{
+	/* unused on non-SPARC architectures */
+}
+
+#endif /* !CONFIG_SPARC */
+
+static struct property * __init build_one_prop(phandle node, char *prev,
+					       char *special_name,
+					       void *special_val,
+					       int special_len)
+{
+	static struct property *tmp = NULL;
+	struct property *p;
+	const char *name;
+
+	if (tmp) {
+		p = tmp;
+		memset(p, 0, sizeof(*p) + 32);
+		tmp = NULL;
+	} else {
+		p = prom_early_alloc(sizeof(struct property) + 32);
+		inc_unique_id(p);
+	}
+
+	p->name = (char *) (p + 1);
+	if (special_name) {
+		strcpy(p->name, special_name);
+		p->length = special_len;
+		p->value = prom_early_alloc(special_len);
+		memcpy(p->value, special_val, special_len);
+	} else {
+		if (prev == NULL) {
+			name = prom_firstprop(node, p->name);
+		} else {
+			name = prom_nextprop(node, prev, p->name);
+		}
+
+		if (!name || strlen(name) == 0) {
+			tmp = p;
+			return NULL;
+		}
+#ifdef CONFIG_SPARC32
+		strcpy(p->name, name);
+#endif
+		p->length = prom_getproplen(node, p->name);
+		if (p->length <= 0) {
+			p->length = 0;
+		} else {
+			int len;
+
+			p->value = prom_early_alloc(p->length + 1);
+			len = prom_getproperty(node, p->name, p->value,
+					       p->length);
+			if (len <= 0)
+				p->length = 0;
+			((unsigned char *)p->value)[p->length] = '\0';
+		}
+	}
+	return p;
+}
+
+static struct property * __init build_prop_list(phandle node)
+{
+	struct property *head, *tail;
+
+	head = tail = build_one_prop(node, NULL,
+				     ".node", &node, sizeof(node));
+
+	tail->next = build_one_prop(node, NULL, NULL, NULL, 0);
+	tail = tail->next;
+	while(tail) {
+		tail->next = build_one_prop(node, tail->name,
+					    NULL, NULL, 0);
+		tail = tail->next;
+	}
+
+	return head;
+}
+
+static char * __init get_one_property(phandle node, const char *name)
+{
+	char *buf = "<NULL>";
+	int len;
+
+	len = prom_getproplen(node, name);
+	if (len > 0) {
+		buf = prom_early_alloc(len);
+		len = prom_getproperty(node, name, buf, len);
+	}
+
+	return buf;
+}
+
+struct device_node * __init prom_create_node(phandle node,
+					     struct device_node *parent)
+{
+	struct device_node *dp;
+
+	if (!node)
+		return NULL;
+
+	dp = prom_early_alloc(sizeof(*dp));
+	inc_unique_id(dp);
+	dp->parent = parent;
+
+	kref_init(&dp->kref);
+
+	dp->name = get_one_property(node, "name");
+	dp->type = get_one_property(node, "device_type");
+	dp->phandle = node;
+
+	dp->properties = build_prop_list(node);
+
+	irq_trans_init(dp);
+
+	return dp;
+}
+
+static char * __init build_full_name(struct device_node *dp)
+{
+	int len, ourlen, plen;
+	char *n;
+
+	plen = strlen(dp->parent->full_name);
+	ourlen = strlen(fetch_node_name(dp));
+	len = ourlen + plen + 2;
+
+	n = prom_early_alloc(len);
+	strcpy(n, dp->parent->full_name);
+	if (!is_root_node(dp->parent)) {
+		strcpy(n + plen, "/");
+		plen++;
+	}
+	strcpy(n + plen, fetch_node_name(dp));
+
+	return n;
+}
+
+struct device_node * __init prom_build_tree(struct device_node *parent,
+					    phandle node,
+					    struct device_node ***nextp)
+{
+	struct device_node *ret = NULL, *prev_sibling = NULL;
+	struct device_node *dp;
+
+	while (1) {
+		dp = prom_create_node(node, parent);
+		if (!dp)
+			break;
+
+		if (prev_sibling)
+			prev_sibling->sibling = dp;
+
+		if (!ret)
+			ret = dp;
+		prev_sibling = dp;
+
+		*(*nextp) = dp;
+		*nextp = &dp->allnext;
+
+#if defined(CONFIG_SPARC)
+		dp->path_component_name = build_path_component(dp);
+#endif
+		dp->full_name = build_full_name(dp);
+
+		dp->child = prom_build_tree(dp, prom_getchild(node), nextp);
+
+		if (prom_build_more)
+			prom_build_more(dp, nextp);
+
+		node = prom_getsibling(node);
+	}
+
+	return ret;
+}
diff --git a/include/linux/of_pdt.h b/include/linux/of_pdt.h
new file mode 100644
index 0000000..f62616e
--- /dev/null
+++ b/include/linux/of_pdt.h
@@ -0,0 +1,37 @@ 
+#include <linux/of.h>	/* linux/of.h gets to determine #include ordering */
+/*
+ * Definitions for building a device tree by calling into the
+ * Open Firmware PROM.
+ *
+ * Copyright (C) 1996-2005 Paul Mackerras.
+ * Copyright (C) 2010  Andres Salomon <dilinger@queued.net>
+ *
+ * Updates for PPC64 by Peter Bergner & David Engebretsen, IBM Corp.
+ * Updates for SPARC by David S. Miller
+ *
+ * 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 _LINUX_OF_PDT_H
+#define _LINUX_OF_PDT_H
+
+extern struct device_node *prom_create_node(phandle node,
+					    struct device_node *parent);
+extern struct device_node *prom_build_tree(struct device_node *parent,
+					   phandle node,
+					   struct device_node ***nextp);
+
+extern void (*prom_build_more)(struct device_node *dp, struct device_node ***nextp);
+
+static inline int is_root_node(const struct device_node *dp)
+{
+	if (!dp)
+		return 0;
+
+	return (dp->parent == NULL);
+}
+
+#endif /* _LINUX_OF_PDT_H */