[PATCH v2 3/3] ARC: setup cpu possible mask according to possible-cpus dts property

[Eugeniy Paltsev]

As we have option in u-boot to set CPU mask for running linux,
we want to pass information to kernel about CPU cores should
be brought up. So we patch kernel dtb in u-boot to set
possible-cpus property.

This also allows us to have correctly setuped MCIP debug mask.

Signed-off-by: Eugeniy Paltsev 
---

Changes v1->v2:
 * no changes.

 arch/arc/kernel/smp.c | 50 --
 1 file changed, 40 insertions(+), 10 deletions(-)

diff --git a/arch/arc/kernel/smp.c b/arch/arc/kernel/smp.c
index efe8b42..21d86c3 100644
--- a/arch/arc/kernel/smp.c
+++ b/arch/arc/kernel/smp.c
@@ -24,6 +24,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #include 
 #include 
@@ -47,6 +48,42 @@ void __init smp_prepare_boot_cpu(void)
 {
 }
 
+static int __init arc_get_cpu_map(const char *name, struct cpumask *cpumask)
+{
+   unsigned long dt_root = of_get_flat_dt_root();
+   const char *buf;
+
+   buf = of_get_flat_dt_prop(dt_root, name, NULL);
+   if (!buf)
+   return -EINVAL;
+
+   if (cpulist_parse(buf, cpumask))
+   return -EINVAL;
+
+   return 0;
+}
+
+/*
+ * Read from DeviceTree and setup cpu possible mask. If there is no
+ * "possible-cpus" property in DeviceTree pretend all [0..NR_CPUS-1] exist.
+ */
+static void __init arc_init_cpu_possible(void)
+{
+   struct cpumask cpumask;
+
+   if (arc_get_cpu_map("possible-cpus", )) {
+   pr_warn("Failed to get possible-cpus from dtb, pretending all 
%u cpus exist\n",
+   NR_CPUS);
+
+   cpumask_setall();
+   }
+
+   if (!cpumask_test_cpu(0, ))
+   panic("Master cpu (cpu[0]) is missed in cpu possible mask!");
+
+   init_cpu_possible();
+}
+
 /*
  * Called from setup_arch() before calling setup_processor()
  *
@@ -58,10 +95,7 @@ void __init smp_prepare_boot_cpu(void)
  */
 void __init smp_init_cpus(void)
 {
-   unsigned int i;
-
-   for (i = 0; i < NR_CPUS; i++)
-   set_cpu_possible(i, true);
+   arc_init_cpu_possible();
 
if (plat_smp_ops.init_early_smp)
plat_smp_ops.init_early_smp();
@@ -70,16 +104,12 @@ void __init smp_init_cpus(void)
 /* called from init ( ) =>  process 1 */
 void __init smp_prepare_cpus(unsigned int max_cpus)
 {
-   int i;
-
/*
 * if platform didn't set the present map already, do it now
 * boot cpu is set to present already by init/main.c
 */
-   if (num_present_cpus() <= 1) {
-   for (i = 0; i < max_cpus; i++)
-   set_cpu_present(i, true);
-   }
+   if (num_present_cpus() <= 1)
+   init_cpu_present(cpu_possible_mask);
 }
 
 void __init smp_cpus_done(unsigned int max_cpus)
-- 
2.9.3

[PATCH v2 3/3] ARC: setup cpu possible mask according to possible-cpus dts property

[Eugeniy Paltsev]

As we have option in u-boot to set CPU mask for running linux,
we want to pass information to kernel about CPU cores should
be brought up. So we patch kernel dtb in u-boot to set
possible-cpus property.

This also allows us to have correctly setuped MCIP debug mask.

Signed-off-by: Eugeniy Paltsev 
---

Changes v1->v2:
 * no changes.

 arch/arc/kernel/smp.c | 50 --
 1 file changed, 40 insertions(+), 10 deletions(-)

diff --git a/arch/arc/kernel/smp.c b/arch/arc/kernel/smp.c
index efe8b42..21d86c3 100644
--- a/arch/arc/kernel/smp.c
+++ b/arch/arc/kernel/smp.c
@@ -24,6 +24,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #include 
 #include 
@@ -47,6 +48,42 @@ void __init smp_prepare_boot_cpu(void)
 {
 }
 
+static int __init arc_get_cpu_map(const char *name, struct cpumask *cpumask)
+{
+   unsigned long dt_root = of_get_flat_dt_root();
+   const char *buf;
+
+   buf = of_get_flat_dt_prop(dt_root, name, NULL);
+   if (!buf)
+   return -EINVAL;
+
+   if (cpulist_parse(buf, cpumask))
+   return -EINVAL;
+
+   return 0;
+}
+
+/*
+ * Read from DeviceTree and setup cpu possible mask. If there is no
+ * "possible-cpus" property in DeviceTree pretend all [0..NR_CPUS-1] exist.
+ */
+static void __init arc_init_cpu_possible(void)
+{
+   struct cpumask cpumask;
+
+   if (arc_get_cpu_map("possible-cpus", )) {
+   pr_warn("Failed to get possible-cpus from dtb, pretending all 
%u cpus exist\n",
+   NR_CPUS);
+
+   cpumask_setall();
+   }
+
+   if (!cpumask_test_cpu(0, ))
+   panic("Master cpu (cpu[0]) is missed in cpu possible mask!");
+
+   init_cpu_possible();
+}
+
 /*
  * Called from setup_arch() before calling setup_processor()
  *
@@ -58,10 +95,7 @@ void __init smp_prepare_boot_cpu(void)
  */
 void __init smp_init_cpus(void)
 {
-   unsigned int i;
-
-   for (i = 0; i < NR_CPUS; i++)
-   set_cpu_possible(i, true);
+   arc_init_cpu_possible();
 
if (plat_smp_ops.init_early_smp)
plat_smp_ops.init_early_smp();
@@ -70,16 +104,12 @@ void __init smp_init_cpus(void)
 /* called from init ( ) =>  process 1 */
 void __init smp_prepare_cpus(unsigned int max_cpus)
 {
-   int i;
-
/*
 * if platform didn't set the present map already, do it now
 * boot cpu is set to present already by init/main.c
 */
-   if (num_present_cpus() <= 1) {
-   for (i = 0; i < max_cpus; i++)
-   set_cpu_present(i, true);
-   }
+   if (num_present_cpus() <= 1)
+   init_cpu_present(cpu_possible_mask);
 }
 
 void __init smp_cpus_done(unsigned int max_cpus)
-- 
2.9.3