On Tue, Apr 22, 2014 at 09:21:16PM +0100, Mark Brown wrote:
From: Mark Brown broonie@linaro.org
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
arch/arm64/kernel/topology.c | 203 +++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 195 insertions(+), 8 deletions(-)
diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c index ff662b23af5f..a326f5b37546 100644 --- a/arch/arm64/kernel/topology.c +++ b/arch/arm64/kernel/topology.c @@ -17,10 +17,191 @@ #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 +220,7 @@ 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.@@ -71,15 +251,10 @@ 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 +268,15 @@ 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();+}
I tested it and tried to clobber it a bit with some DT changes, it seems fine.
Apart from an ultra-minor decoration change (attached):
Reviewed-by: Lorenzo Pieralisi lorenzo.pieralisi@arm.com