On Tue, Jul 6, 2010 at 3:54 PM, Andres Salomon [off-list ref] wrote:

On Tue, 6 Jul 2010 03:21:21 -0600
Grant Likely [off-list ref] wrote:

quoted

On Mon, Jun 28, 2010 at 8:00 PM, Andres Salomon [off-list ref]
wrote:

quoted

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 <redacted>

Some more comments below...

Thanks for the review!

quoted

quoted

 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.

[...]

quoted

quoted

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.

[...]

quoted

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.

-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.