x86, olpc: Add OLPC device-tree support

Make use of PROC_DEVICETREE to export the tree, and sparc's PROMTREE code to
call into OLPC's Open Firmware to build the tree.

v5: fix buglet with root node check (introduced in v4)

v4: address some minor style issues pointed out by Grant, and explicitly cast
    negative phandle checks to s32.

v3: rename olpc_prom to olpc_dt
  - rework Kconfig entries
  - drop devtree build hook from proc, instead adding a call to x86's
    paging_init (similarly to how sparc64 does it)
  - switch allocation from using slab to alloc_bootmem.  this allows
    the DT to be built earlier during boot (during setup_arch); the
    downside is that there are some 1200 bootmem reservations that are
    done during boot.  Not ideal..
  - add a helper olpc_ofw_is_installed function to test for the
    existence and successful detection of OLPC's OFW.

Signed-off-by: Andres Salomon <dilinger@queued.net>
LKML-Reference: <20101116220952.26526a80@queued.net>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

arch/x86/Kconfig

@@ -2049,11 +2049,17 @@ config OLPC_OPENFIRMWARE
 	bool "Support for OLPC's Open Firmware"
 	depends on !X86_64 && !X86_PAE
 	default n
+	select OF
 	help
 	  This option adds support for the implementation of Open Firmware
 	  that is used on the OLPC XO-1 Children's Machine.
 	  If unsure, say N here.
 
+config OLPC_OPENFIRMWARE_DT
+	bool
+	default y if OLPC_OPENFIRMWARE && PROC_DEVICETREE
+	select OF_PROMTREE
+
 endif # X86_32
 
 config AMD_NB

arch/x86/include/asm/olpc_ofw.h

@@ -8,6 +8,8 @@
 
 #ifdef CONFIG_OLPC_OPENFIRMWARE
 
+extern bool olpc_ofw_is_installed(void);
+
 /* run an OFW command by calling into the firmware */
 #define olpc_ofw(name, args, res) \
 	__olpc_ofw((name), ARRAY_SIZE(args), args, ARRAY_SIZE(res), res)
@@ -26,10 +28,17 @@ extern bool olpc_ofw_present(void);
 
 #else /* !CONFIG_OLPC_OPENFIRMWARE */
 
+static inline bool olpc_ofw_is_installed(void) { return false; }
 static inline void olpc_ofw_detect(void) { }
 static inline void setup_olpc_ofw_pgd(void) { }
 static inline bool olpc_ofw_present(void) { return false; }
 
 #endif /* !CONFIG_OLPC_OPENFIRMWARE */
 
+#ifdef CONFIG_OLPC_OPENFIRMWARE_DT
+extern void olpc_dt_build_devicetree(void);
+#else
+static inline void olpc_dt_build_devicetree(void) { }
+#endif /* CONFIG_OLPC_OPENFIRMWARE_DT */
+
 #endif /* _ASM_X86_OLPC_OFW_H */

arch/x86/include/asm/prom.h

@@ -0,0 +1 @@
+/* dummy prom.h; here to make linux/of.h's #includes happy */

arch/x86/mm/init_32.c

@@ -45,6 +45,7 @@
 #include <asm/bugs.h>
 #include <asm/tlb.h>
 #include <asm/tlbflush.h>
+#include <asm/olpc_ofw.h>
 #include <asm/pgalloc.h>
 #include <asm/sections.h>
 #include <asm/paravirt.h>
@@ -715,6 +716,7 @@ void __init paging_init(void)
 	/*
 	 * NOTE: at this point the bootmem allocator is fully available.
 	 */
+	olpc_dt_build_devicetree();
 	sparse_init();
 	zone_sizes_init();
 }

arch/x86/platform/olpc/Makefile

@@ -1,3 +1,4 @@
 obj-$(CONFIG_OLPC)		+= olpc.o
 obj-$(CONFIG_OLPC_XO1)		+= olpc-xo1.o
 obj-$(CONFIG_OLPC_OPENFIRMWARE)	+= olpc_ofw.o
+obj-$(CONFIG_OLPC_OPENFIRMWARE_DT)	+= olpc_dt.o

arch/x86/platform/olpc/olpc_dt.c

@@ -0,0 +1,165 @@
+/*
+ * OLPC-specific OFW device tree support code.
+ *
+ * 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 x86/OLPC 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/bootmem.h>
+#include <linux/of.h>
+#include <linux/of_pdt.h>
+#include <asm/olpc_ofw.h>
+
+static phandle __init olpc_dt_getsibling(phandle node)
+{
+	const void *args[] = { (void *)node };
+	void *res[] = { &node };
+
+	if ((s32)node == -1)
+		return 0;
+
+	if (olpc_ofw("peer", args, res) || (s32)node == -1)
+		return 0;
+
+	return node;
+}
+
+static phandle __init olpc_dt_getchild(phandle node)
+{
+	const void *args[] = { (void *)node };
+	void *res[] = { &node };
+
+	if ((s32)node == -1)
+		return 0;
+
+	if (olpc_ofw("child", args, res) || (s32)node == -1) {
+		pr_err("PROM: %s: fetching child failed!\n", __func__);
+		return 0;
+	}
+
+	return node;
+}
+
+static int __init olpc_dt_getproplen(phandle node, const char *prop)
+{
+	const void *args[] = { (void *)node, prop };
+	int len;
+	void *res[] = { &len };
+
+	if ((s32)node == -1)
+		return -1;
+
+	if (olpc_ofw("getproplen", args, res)) {
+		pr_err("PROM: %s: getproplen failed!\n", __func__);
+		return -1;
+	}
+
+	return len;
+}
+
+static int __init olpc_dt_getproperty(phandle node, const char *prop,
+		char *buf, int bufsize)
+{
+	int plen;
+
+	plen = olpc_dt_getproplen(node, prop);
+	if (plen > bufsize || plen < 1) {
+		return -1;
+	} else {
+		const void *args[] = { (void *)node, prop, buf, (void *)plen };
+		void *res[] = { &plen };
+
+		if (olpc_ofw("getprop", args, res)) {
+			pr_err("PROM: %s: getprop failed!\n", __func__);
+			return -1;
+		}
+	}
+
+	return plen;
+}
+
+static int __init olpc_dt_nextprop(phandle node, char *prev, char *buf)
+{
+	const void *args[] = { (void *)node, prev, buf };
+	int success;
+	void *res[] = { &success };
+
+	buf[0] = '\0';
+
+	if ((s32)node == -1)
+		return -1;
+
+	if (olpc_ofw("nextprop", args, res) || success != 1)
+		return -1;
+
+	return 0;
+}
+
+static int __init olpc_dt_pkg2path(phandle node, char *buf,
+		const int buflen, int *len)
+{
+	const void *args[] = { (void *)node, buf, (void *)buflen };
+	void *res[] = { len };
+
+	if ((s32)node == -1)
+		return -1;
+
+	if (olpc_ofw("package-to-path", args, res) || *len < 1)
+		return -1;
+
+	return 0;
+}
+
+static unsigned int prom_early_allocated __initdata;
+
+void * __init prom_early_alloc(unsigned long size)
+{
+	void *res;
+
+	res = alloc_bootmem(size);
+	if (res)
+		memset(res, 0, size);
+
+	prom_early_allocated += size;
+
+	return res;
+}
+
+static struct of_pdt_ops prom_olpc_ops __initdata = {
+	.nextprop = olpc_dt_nextprop,
+	.getproplen = olpc_dt_getproplen,
+	.getproperty = olpc_dt_getproperty,
+	.getchild = olpc_dt_getchild,
+	.getsibling = olpc_dt_getsibling,
+	.pkg2path = olpc_dt_pkg2path,
+};
+
+void __init olpc_dt_build_devicetree(void)
+{
+	phandle root;
+
+	if (!olpc_ofw_is_installed())
+		return;
+
+	root = olpc_dt_getsibling(0);
+	if (!root) {
+		pr_err("PROM: unable to get root node from OFW!\n");
+		return;
+	}
+	of_pdt_build_devicetree(root, &prom_olpc_ops);
+
+	pr_info("PROM DT: Built device tree with %u bytes of memory.\n",
+			prom_early_allocated);
+}

arch/x86/platform/olpc/olpc_ofw.c

@@ -110,3 +110,8 @@ void __init olpc_ofw_detect(void)
 			(unsigned long)olpc_ofw_cif, (-start) >> 20);
 	reserve_top_address(-start);
 }
+
+bool __init olpc_ofw_is_installed(void)
+{
+	return olpc_ofw_cif != NULL;
+}