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authorMark Brown <broonie@linaro.org>2014-04-06 19:45:46 +0100
committerMark Brown <broonie@linaro.org>2014-05-09 21:38:44 +0100
commit3252efc39608be2aac69c184559b9ae168003284 (patch)
tree7d28acd5ff8bafca93dc72df132a1f4d99afbf6c
parent8759b2d0f8067d726c269602ffe310221437ce5e (diff)
downloadlinux-linaro-stable-3252efc39608be2aac69c184559b9ae168003284.tar.gz
arm64: topology: Add support for topology DT bindings
Add support for parsing the explicit topology bindings to discover the topology of the system. Since it is not currently clear how to map multi-level clusters for the scheduler all leaf clusters are presented to the scheduler at the same level. This should be enough to provide good support for current systems. Signed-off-by: Mark Brown <broonie@linaro.org> Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
-rw-r--r--arch/arm64/kernel/topology.c204
1 files changed, 196 insertions, 8 deletions
diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
index ff662b23af5f..43514f905916 100644
--- a/arch/arm64/kernel/topology.c
+++ b/arch/arm64/kernel/topology.c
@@ -17,10 +17,192 @@
#include <linux/percpu.h>
#include <linux/node.h>
#include <linux/nodemask.h>
+#include <linux/of.h>
#include <linux/sched.h>
#include <asm/topology.h>
+static int __init get_cpu_for_node(struct device_node *node)
+{
+ struct device_node *cpu_node;
+ int cpu;
+
+ cpu_node = of_parse_phandle(node, "cpu", 0);
+ if (!cpu_node)
+ return -1;
+
+ for_each_possible_cpu(cpu) {
+ if (of_get_cpu_node(cpu, NULL) == cpu_node) {
+ of_node_put(cpu_node);
+ return cpu;
+ }
+ }
+
+ pr_crit("Unable to find CPU node for %s\n", cpu_node->full_name);
+
+ of_node_put(cpu_node);
+ return -1;
+}
+
+static int __init parse_core(struct device_node *core, int cluster_id,
+ int core_id)
+{
+ char name[10];
+ bool leaf = true;
+ int i = 0;
+ int cpu;
+ struct device_node *t;
+
+ do {
+ snprintf(name, sizeof(name), "thread%d", i);
+ t = of_get_child_by_name(core, name);
+ if (t) {
+ leaf = false;
+ cpu = get_cpu_for_node(t);
+ if (cpu >= 0) {
+ cpu_topology[cpu].cluster_id = cluster_id;
+ cpu_topology[cpu].core_id = core_id;
+ cpu_topology[cpu].thread_id = i;
+ } else {
+ pr_err("%s: Can't get CPU for thread\n",
+ t->full_name);
+ of_node_put(t);
+ return -EINVAL;
+ }
+ of_node_put(t);
+ }
+ i++;
+ } while (t);
+
+ cpu = get_cpu_for_node(core);
+ if (cpu >= 0) {
+ if (!leaf) {
+ pr_err("%s: Core has both threads and CPU\n",
+ core->full_name);
+ return -EINVAL;
+ }
+
+ cpu_topology[cpu].cluster_id = cluster_id;
+ cpu_topology[cpu].core_id = core_id;
+ } else if (leaf) {
+ pr_err("%s: Can't get CPU for leaf core\n", core->full_name);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int __init parse_cluster(struct device_node *cluster, int depth)
+{
+ char name[10];
+ bool leaf = true;
+ bool has_cores = false;
+ struct device_node *c;
+ static int cluster_id __initdata;
+ int core_id = 0;
+ int i, ret;
+
+ /*
+ * First check for child clusters; we currently ignore any
+ * information about the nesting of clusters and present the
+ * scheduler with a flat list of them.
+ */
+ i = 0;
+ do {
+ snprintf(name, sizeof(name), "cluster%d", i);
+ c = of_get_child_by_name(cluster, name);
+ if (c) {
+ leaf = false;
+ ret = parse_cluster(c, depth + 1);
+ of_node_put(c);
+ if (ret != 0)
+ return ret;
+ }
+ i++;
+ } while (c);
+
+ /* Now check for cores */
+ i = 0;
+ do {
+ snprintf(name, sizeof(name), "core%d", i);
+ c = of_get_child_by_name(cluster, name);
+ if (c) {
+ has_cores = true;
+
+ if (depth == 0) {
+ pr_err("%s: cpu-map children should be clusters\n",
+ c->full_name);
+ of_node_put(c);
+ return -EINVAL;
+ }
+
+ if (leaf) {
+ ret = parse_core(c, cluster_id, core_id++);
+ } else {
+ pr_err("%s: Non-leaf cluster with core %s\n",
+ cluster->full_name, name);
+ ret = -EINVAL;
+ }
+
+ of_node_put(c);
+ if (ret != 0)
+ return ret;
+ }
+ i++;
+ } while (c);
+
+ if (leaf && !has_cores)
+ pr_warn("%s: empty cluster\n", cluster->full_name);
+
+ if (leaf)
+ cluster_id++;
+
+ return 0;
+}
+
+static int __init parse_dt_topology(void)
+{
+ struct device_node *cn, *map;
+ int ret = 0;
+ int cpu;
+
+ cn = of_find_node_by_path("/cpus");
+ if (!cn) {
+ pr_err("No CPU information found in DT\n");
+ return 0;
+ }
+
+ /*
+ * When topology is provided cpu-map is essentially a root
+ * cluster with restricted subnodes.
+ */
+ map = of_get_child_by_name(cn, "cpu-map");
+ if (!map)
+ goto out;
+
+ ret = parse_cluster(map, 0);
+ if (ret != 0)
+ goto out_map;
+
+ /*
+ * Check that all cores are in the topology; the SMP code will
+ * only mark cores described in the DT as possible.
+ */
+ for_each_possible_cpu(cpu) {
+ if (cpu_topology[cpu].cluster_id == -1) {
+ pr_err("CPU%d: No topology information specified\n",
+ cpu);
+ ret = -EINVAL;
+ }
+ }
+
+out_map:
+ of_node_put(map);
+out:
+ of_node_put(cn);
+ return ret;
+}
+
/*
* cpu topology table
*/
@@ -39,8 +221,7 @@ static void update_siblings_masks(unsigned int cpuid)
if (cpuid_topo->cluster_id == -1) {
/*
- * DT does not contain topology information for this cpu
- * reset it to default behaviour
+ * DT does not contain topology information for this cpu.
*/
pr_debug("CPU%u: No topology information configured\n", cpuid);
return;
@@ -71,15 +252,10 @@ void store_cpu_topology(unsigned int cpuid)
update_siblings_masks(cpuid);
}
-/*
- * init_cpu_topology is called at boot when only one cpu is running
- * which prevent simultaneous write access to cpu_topology array
- */
-void __init init_cpu_topology(void)
+static void __init reset_cpu_topology(void)
{
unsigned int cpu;
- /* init core mask and power*/
for_each_possible_cpu(cpu) {
struct cpu_topology *cpu_topo = &cpu_topology[cpu];
@@ -93,3 +269,15 @@ void __init init_cpu_topology(void)
cpumask_set_cpu(cpu, &cpu_topo->thread_sibling);
}
}
+
+void __init init_cpu_topology(void)
+{
+ reset_cpu_topology();
+
+ /*
+ * Discard anything that was parsed if we hit an error so we
+ * don't use partial information.
+ */
+ if (parse_dt_topology())
+ reset_cpu_topology();
+}