diff --git a/Documentation/devicetree/bindings/arm/cpus.txt b/Documentation/devicetree/bindings/arm/cpus.txt
new file mode 100644
index 0000000000000000000000000000000000000000..f32494dbfe194202e05e556f6509d303a4e194d6
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/cpus.txt
@@ -0,0 +1,77 @@
+* ARM CPUs binding description
+
+The device tree allows to describe the layout of CPUs in a system through
+the "cpus" node, which in turn contains a number of subnodes (ie "cpu")
+defining properties for every cpu.
+
+Bindings for CPU nodes follow the ePAPR standard, available from:
+
+http://devicetree.org
+
+For the ARM architecture every CPU node must contain the following properties:
+
+- device_type: must be "cpu"
+- reg: property matching the CPU MPIDR[23:0] register bits
+ reg[31:24] bits must be set to 0
+- compatible: should be one of:
+ "arm,arm1020"
+ "arm,arm1020e"
+ "arm,arm1022"
+ "arm,arm1026"
+ "arm,arm720"
+ "arm,arm740"
+ "arm,arm7tdmi"
+ "arm,arm920"
+ "arm,arm922"
+ "arm,arm925"
+ "arm,arm926"
+ "arm,arm940"
+ "arm,arm946"
+ "arm,arm9tdmi"
+ "arm,cortex-a5"
+ "arm,cortex-a7"
+ "arm,cortex-a8"
+ "arm,cortex-a9"
+ "arm,cortex-a15"
+ "arm,arm1136"
+ "arm,arm1156"
+ "arm,arm1176"
+ "arm,arm11mpcore"
+ "faraday,fa526"
+ "intel,sa110"
+ "intel,sa1100"
+ "marvell,feroceon"
+ "marvell,mohawk"
+ "marvell,xsc3"
+ "marvell,xscale"
+
+Example:
+
+ cpus {
+ #size-cells = <0>;
+ #address-cells = <1>;
+
+ CPU0: cpu@0 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a15";
+ reg = <0x0>;
+ };
+
+ CPU1: cpu@1 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a15";
+ reg = <0x1>;
+ };
+
+ CPU2: cpu@100 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a7";
+ reg = <0x100>;
+ };
+
+ CPU3: cpu@101 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a7";
+ reg = <0x101>;
+ };
+ };
diff --git a/arch/arm/include/asm/prom.h b/arch/arm/include/asm/prom.h
index aeae9c609df4885570646d076741cef0565328da..8dd51dc1a36724dac90b8e7e8199667e788f569d 100644
--- a/arch/arm/include/asm/prom.h
+++ b/arch/arm/include/asm/prom.h
@@ -15,6 +15,7 @@
extern struct machine_desc *setup_machine_fdt(unsigned int dt_phys);
extern void arm_dt_memblock_reserve(void);
+extern void __init arm_dt_init_cpu_maps(void);
#else /* CONFIG_OF */
@@ -24,6 +25,7 @@ static inline struct machine_desc *setup_machine_fdt(unsigned int dt_phys)
}
static inline void arm_dt_memblock_reserve(void) { }
+static inline void arm_dt_init_cpu_maps(void) { }
#endif /* CONFIG_OF */
#endif /* ASMARM_PROM_H */
diff --git a/arch/arm/kernel/devtree.c b/arch/arm/kernel/devtree.c
index bee7f9d47f02f2b702bb59df7fee1f81e34590eb..aaf9add497fe2bab5fff699309afdeb498c7c5d6 100644
--- a/arch/arm/kernel/devtree.c
+++ b/arch/arm/kernel/devtree.c
@@ -19,8 +19,10 @@
#include <linux/of_irq.h>
#include <linux/of_platform.h>
+#include <asm/cputype.h>
#include <asm/setup.h>
#include <asm/page.h>
+#include <asm/smp_plat.h>
#include <asm/mach/arch.h>
#include <asm/mach-types.h>
@@ -61,6 +63,104 @@ void __init arm_dt_memblock_reserve(void)
}
}
+/*
+ * arm_dt_init_cpu_maps - Function retrieves cpu nodes from the device tree
+ * and builds the cpu logical map array containing MPIDR values related to
+ * logical cpus
+ *
+ * Updates the cpu possible mask with the number of parsed cpu nodes
+ */
+void __init arm_dt_init_cpu_maps(void)
+{
+ /*
+ * Temp logical map is initialized with UINT_MAX values that are
+ * considered invalid logical map entries since the logical map must
+ * contain a list of MPIDR[23:0] values where MPIDR[31:24] must
+ * read as 0.
+ */
+ struct device_node *cpu, *cpus;
+ u32 i, j, cpuidx = 1;
+ u32 mpidr = is_smp() ? read_cpuid_mpidr() & MPIDR_HWID_BITMASK : 0;
+
+ u32 tmp_map[NR_CPUS] = { [0 ... NR_CPUS-1] = UINT_MAX };
+ bool bootcpu_valid = false;
+ cpus = of_find_node_by_path("/cpus");
+
+ if (!cpus)
+ return;
+
+ for_each_child_of_node(cpus, cpu) {
+ u32 hwid;
+
+ pr_debug(" * %s...\n", cpu->full_name);
+ /*
+ * A device tree containing CPU nodes with missing "reg"
+ * properties is considered invalid to build the
+ * cpu_logical_map.
+ */
+ if (of_property_read_u32(cpu, "reg", &hwid)) {
+ pr_debug(" * %s missing reg property\n",
+ cpu->full_name);
+ return;
+ }
+
+ /*
+ * 8 MSBs must be set to 0 in the DT since the reg property
+ * defines the MPIDR[23:0].
+ */
+ if (hwid & ~MPIDR_HWID_BITMASK)
+ return;
+
+ /*
+ * Duplicate MPIDRs are a recipe for disaster.
+ * Scan all initialized entries and check for
+ * duplicates. If any is found just bail out.
+ * temp values were initialized to UINT_MAX
+ * to avoid matching valid MPIDR[23:0] values.
+ */
+ for (j = 0; j < cpuidx; j++)
+ if (WARN(tmp_map[j] == hwid, "Duplicate /cpu reg "
+ "properties in the DT\n"))
+ return;
+
+ /*
+ * Build a stashed array of MPIDR values. Numbering scheme
+ * requires that if detected the boot CPU must be assigned
+ * logical id 0. Other CPUs get sequential indexes starting
+ * from 1. If a CPU node with a reg property matching the
+ * boot CPU MPIDR is detected, this is recorded so that the
+ * logical map built from DT is validated and can be used
+ * to override the map created in smp_setup_processor_id().
+ */
+ if (hwid == mpidr) {
+ i = 0;
+ bootcpu_valid = true;
+ } else {
+ i = cpuidx++;
+ }
+
+ tmp_map[i] = hwid;
+
+ if (cpuidx > nr_cpu_ids)
+ break;
+ }
+
+ if (WARN(!bootcpu_valid, "DT missing boot CPU MPIDR[23:0], "
+ "fall back to default cpu_logical_map\n"))
+ return;
+
+ /*
+ * Since the boot CPU node contains proper data, and all nodes have
+ * a reg property, the DT CPU list can be considered valid and the
+ * logical map created in smp_setup_processor_id() can be overridden
+ */
+ for (i = 0; i < cpuidx; i++) {
+ set_cpu_possible(i, true);
+ cpu_logical_map(i) = tmp_map[i];
+ pr_debug("cpu logical map 0x%x\n", cpu_logical_map(i));
+ }
+}
+
/**
* setup_machine_fdt - Machine setup when an dtb was passed to the kernel
* @dt_phys: physical address of dt blob