xen/arm: get the number of cpus from device tree

The system might have fewer cpus than the GIC supports.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Campbell <ian.campbell@citrix.com>

6 files changed, 71 insertions, 12 deletions

diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
index 5f06e085e0..0c6fab9151 100644
--- a/xen/arch/arm/gic.c
+++ b/xen/arch/arm/gic.c
@@ -304,7 +304,7 @@ static void __cpuinit gic_hyp_disable(void)
 }
 
 /* Set up the GIC */
-int __init gic_init(void)
+void __init gic_init(void)
 {
     /* XXX FIXME get this from devicetree */
     gic.dbase = GIC_BASE_ADDRESS + GIC_DR_OFFSET;
@@ -328,8 +328,6 @@ int __init gic_init(void)
     gic.lr_mask = 0ULL;
 
     spin_unlock(&gic.lock);
-
-    return gic.cpus;
 }
 
 /* Set up the per-CPU parts of the GIC for a secondary CPU */
diff --git a/xen/arch/arm/gic.h b/xen/arch/arm/gic.h
index b2e1d7face..1bf1b02913 100644
--- a/xen/arch/arm/gic.h
+++ b/xen/arch/arm/gic.h
@@ -147,7 +147,7 @@ extern int gic_route_irq_to_guest(struct domain *d, unsigned int irq,
 /* Accept an interrupt from the GIC and dispatch its handler */
 extern void gic_interrupt(struct cpu_user_regs *regs, int is_fiq);
 /* Bring up the interrupt controller, and report # cpus attached */
-extern int gic_init(void);
+extern void gic_init(void);
 /* Bring up a secondary CPU's per-CPU GIC interface */
 extern void gic_init_secondary_cpu(void);
 /* Take down a CPU's per-CPU GIC interface */
diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index 0328394179..c52330ee84 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -185,10 +185,13 @@ void __init start_xen(unsigned long boot_phys_offset,
     size_t fdt_size;
     int cpus, i;
 
+    smp_clear_cpu_maps();
+
     fdt = (void *)BOOT_MISC_VIRT_START
         + (atag_paddr & ((1 << SECOND_SHIFT) - 1));
     fdt_size = device_tree_early_init(fdt);
 
+    cpus = smp_get_max_cpus();
     cmdline_parse(device_tree_bootargs(fdt));
 
     setup_pagetables(boot_phys_offset, get_xen_paddr());
@@ -199,7 +202,7 @@ void __init start_xen(unsigned long boot_phys_offset,
     console_init_preirq();
 #endif
 
-    cpus = gic_init();
+    gic_init();
     make_cpus_ready(cpus, boot_phys_offset);
 
     percpu_init_areas();
diff --git a/xen/arch/arm/smpboot.c b/xen/arch/arm/smpboot.c
index 1b52e22c4a..05c8d8d22c 100644
--- a/xen/arch/arm/smpboot.c
+++ b/xen/arch/arm/smpboot.c
@@ -71,18 +71,31 @@ static void setup_cpu_sibling_map(int cpu)
     cpumask_set_cpu(cpu, per_cpu(cpu_core_mask, cpu));
 }
 
-
 void __init
-smp_prepare_cpus (unsigned int max_cpus)
+smp_clear_cpu_maps (void)
 {
-    int i;
-
+    cpumask_clear(&cpu_possible_map);
     cpumask_clear(&cpu_online_map);
     cpumask_set_cpu(0, &cpu_online_map);
+    cpumask_set_cpu(0, &cpu_possible_map);
+}
 
-    cpumask_clear(&cpu_possible_map);
-    for ( i = 0; i < max_cpus; i++ )
-        cpumask_set_cpu(i, &cpu_possible_map);
+int __init
+smp_get_max_cpus (void)
+{
+    int i, max_cpus = 0;
+
+    for ( i = 0; i < nr_cpu_ids; i++ )
+        if ( cpu_possible(i) )
+            max_cpus++;
+
+    return max_cpus;
+}
+
+
+void __init
+smp_prepare_cpus (unsigned int max_cpus)
+{
     cpumask_copy(&cpu_present_map, &cpu_possible_map);
 
     setup_cpu_sibling_map(0);
diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
index 3d1f0f45fc..da0af77d77 100644
--- a/xen/common/device_tree.c
+++ b/xen/common/device_tree.c
@@ -18,6 +18,7 @@
 #include <xen/mm.h>
 #include <xen/stdarg.h>
 #include <xen/string.h>
+#include <xen/cpumask.h>
 #include <asm/early_printk.h>
 
 struct dt_early_info __initdata early_info;
@@ -41,6 +42,18 @@ bool_t device_tree_node_matches(const void *fdt, int node, const char *match)
         && (name[match_len] == '@' || name[match_len] == '\0');
 }
 
+bool_t device_tree_type_matches(const void *fdt, int node, const char *match)
+{
+    int len;
+    const void *prop;
+
+    prop = fdt_getprop(fdt, node, "device_type", &len);
+    if ( prop == NULL )
+        return 0;
+
+    return !strncmp(prop, match, len);
+}
+
 static void __init get_val(const u32 **cell, u32 cells, u64 *val)
 {
     *val = 0;
@@ -229,6 +242,34 @@ static void __init process_memory_node(const void *fdt, int node,
     }
 }
 
+static void __init process_cpu_node(const void *fdt, int node,
+                                    const char *name,
+                                    u32 address_cells, u32 size_cells)
+{
+    const struct fdt_property *prop;
+    const u32 *cell;
+    paddr_t start, size;
+
+    if ( address_cells != 1 || size_cells != 0 )
+    {
+        early_printk("fdt: node `%s': invalid #address-cells or #size-cells",
+                     name);
+        return;
+    }
+
+    prop = fdt_get_property(fdt, node, "reg", NULL);
+    if ( !prop )
+    {
+        early_printk("fdt: node `%s': missing `reg' property\n", name);
+        return;
+    }
+
+    cell = (const u32 *)prop->data;
+    device_tree_get_reg(&cell, address_cells, size_cells, &start, &size);
+
+    cpumask_set_cpu(start, &cpu_possible_map);
+}
+
 static int __init early_scan_node(const void *fdt,
                                   int node, const char *name, int depth,
                                   u32 address_cells, u32 size_cells,
@@ -236,6 +277,8 @@ static int __init early_scan_node(const void *fdt,
 {
     if ( device_tree_node_matches(fdt, node, "memory") )
         process_memory_node(fdt, node, name, address_cells, size_cells);
+    else if ( device_tree_type_matches(fdt, node, "cpu") )
+        process_cpu_node(fdt, node, name, address_cells, size_cells);
 
     return 0;
 }
diff --git a/xen/include/asm-arm/smp.h b/xen/include/asm-arm/smp.h
index a98032dc2c..d4ed1cb2fd 100644
--- a/xen/include/asm-arm/smp.h
+++ b/xen/include/asm-arm/smp.h
@@ -22,6 +22,8 @@ extern void stop_cpu(void);
 extern void
 make_cpus_ready(unsigned int max_cpus, unsigned long boot_phys_offset);
 
+extern void smp_clear_cpu_maps (void);
+extern int smp_get_max_cpus (void);
 #endif
 /*
  * Local variables: