powerpc/mm: Separate ibm, dynamic-memory data from DT format

We currently have code to parse the dynamic reconfiguration LMB
information from the ibm,dynamic-meory device tree property in
multiple locations; numa.c, prom.c, and pseries/hotplug-memory.c.
In anticipation of adding support for a version 2 of the
ibm,dynamic-memory property this patch aims to separate the device
tree information from the device tree format.

Doing this requires a two step process to avoid a possibly very large
bootmem allocation early in boot. During initial boot, new routines
are provided to walk the device tree property and make a call-back
for each LMB.

The second step (introduced in later patches) will allocate an
array of LMB information that can be used directly without needing
to know the DT format.

This approach provides the benefit of consolidating the device tree
property parsing to a single location and (eventually) providing
a common data structure for retrieving LMB information.

This patch introduces a routine to walk the ibm,dynamic-memory
property in the flattened device tree and updates the prom.c code
to use this to initialize memory.

Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

2 files changed, 77 insertions, 1 deletions

diff --git a/arch/powerpc/mm/Makefile b/arch/powerpc/mm/Makefile
index 76a6b057d454..8d271bfe2d94 100644
--- a/arch/powerpc/mm/Makefile
+++ b/arch/powerpc/mm/Makefile
@@ -9,7 +9,7 @@ ccflags-$(CONFIG_PPC64)	:= $(NO_MINIMAL_TOC)
 
 obj-y				:= fault.o mem.o pgtable.o mmap.o \
 				   init_$(BITS).o pgtable_$(BITS).o \
-				   init-common.o mmu_context.o
+				   init-common.o mmu_context.o drmem.o
 obj-$(CONFIG_PPC_MMU_NOHASH)	+= mmu_context_nohash.o tlb_nohash.o \
 				   tlb_nohash_low.o
 obj-$(CONFIG_PPC_BOOK3E)	+= tlb_low_$(BITS)e.o
diff --git a/arch/powerpc/mm/drmem.c b/arch/powerpc/mm/drmem.c
new file mode 100644
index 000000000000..f8ee0f355405
--- /dev/null
+++ b/arch/powerpc/mm/drmem.c
@@ -0,0 +1,76 @@
+/*
+ * Dynamic reconfiguration memory support
+ *
+ * Copyright 2017 IBM Corporation
+ *
+ * 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.
+ */
+
+#define pr_fmt(fmt) "drmem: " fmt
+
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/memblock.h>
+#include <asm/prom.h>
+#include <asm/drmem.h>
+
+static struct drmem_lmb_info __drmem_info;
+struct drmem_lmb_info *drmem_info = &__drmem_info;
+
+#ifdef CONFIG_PPC_PSERIES
+static void __init read_drconf_v1_cell(struct drmem_lmb *lmb,
+				       const __be32 **prop)
+{
+	const __be32 *p = *prop;
+
+	lmb->base_addr = dt_mem_next_cell(dt_root_addr_cells, &p);
+	lmb->drc_index = of_read_number(p++, 1);
+
+	p++; /* skip reserved field */
+
+	lmb->aa_index = of_read_number(p++, 1);
+	lmb->flags = of_read_number(p++, 1);
+
+	*prop = p;
+}
+
+static void __init __walk_drmem_v1_lmbs(const __be32 *prop, const __be32 *usm,
+			void (*func)(struct drmem_lmb *, const __be32 **))
+{
+	struct drmem_lmb lmb;
+	u32 i, n_lmbs;
+
+	n_lmbs = of_read_number(prop++, 1);
+
+	for (i = 0; i < n_lmbs; i++) {
+		read_drconf_v1_cell(&lmb, &prop);
+		func(&lmb, &usm);
+	}
+}
+
+void __init walk_drmem_lmbs_early(unsigned long node,
+			void (*func)(struct drmem_lmb *, const __be32 **))
+{
+	const __be32 *prop, *usm;
+	int len;
+
+	prop = of_get_flat_dt_prop(node, "ibm,lmb-size", &len);
+	if (!prop || len < dt_root_size_cells * sizeof(__be32))
+		return;
+
+	drmem_info->lmb_size = dt_mem_next_cell(dt_root_size_cells, &prop);
+
+	usm = of_get_flat_dt_prop(node, "linux,drconf-usable-memory", &len);
+
+	prop = of_get_flat_dt_prop(node, "ibm,dynamic-memory", &len);
+	if (prop)
+		__walk_drmem_v1_lmbs(prop, usm, func);
+
+	memblock_dump_all();
+}
+
+#endif