ARM: Introduce CPU_METHOD_OF_DECLARE() for cpu hotplug/smp

The goal of multi-platform kernels is to remove the need for mach directories and machine descriptors. To further that goal, introduce CPU_METHOD_OF_DECLARE() to allow cpu hotplug/smp support to be separated from the machine descriptors. Implementers should specify an enable-method property in their cpus node and then implement a matching set of smp_ops in their hotplug/smp code, wiring it up with the CPU_METHOD_OF_DECLARE() macro. When the kernel is compiled we'll collect all the enable-method smp_ops into one section for use at boot. At boot time we'll look for an enable-method in each cpu node and try to match that against all known CPU enable methods in the kernel. If there are no enable-methods in the cpu nodes we fallback to the cpus node and try to use any enable-method found there. If that doesn't work we fall back to the old way of using the machine descriptor. Acked-by: Mark Rutland <mark.rutland@arm.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: <devicetree@vger.kernel.org> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Kumar Gala <galak@codeaurora.org>

ARM: Introduce CPU_METHOD_OF_DECLARE() for cpu hotplug/smp
The goal of multi-platform kernels is to remove the need for mach directories and machine descriptors. To further that goal, introduce CPU_METHOD_OF_DECLARE() to allow cpu hotplug/smp support to be separated from the machine descriptors. Implementers should specify an enable-method property in their cpus node and then implement a matching set of smp_ops in their hotplug/smp code, wiring it up with the CPU_METHOD_OF_DECLARE() macro. When the kernel is compiled we'll collect all the enable-method smp_ops into one section for use at boot. At boot time we'll look for an enable-method in each cpu node and try to match that against all known CPU enable methods in the kernel. If there are no enable-methods in the cpu nodes we fallback to the cpus node and try to use any enable-method found there. If that doesn't work we fall back to the old way of using the machine descriptor. Acked-by: Mark Rutland <mark.rutland@arm.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: <devicetree@vger.kernel.org> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Kumar Gala <galak@codeaurora.org>
Stephen Boyd · Kumar Gala
1 parent cf1e8f0cd6
Showing 3 changed files with 59 additions and 0 deletions Side-by-side Diff
arch/arm/include/asm/smp.h
arch/arm/kernel/devtree.c
include/asm-generic/vmlinux.lds.h
@@ -114,6 +114,15 @@
 #endif
 };
  
+struct of_cpu_method {
+	const char *method;
+	struct smp_operations *ops;
+};
+
+#define CPU_METHOD_OF_DECLARE(name, _method, _ops)			\
+	static const struct of_cpu_method __cpu_method_of_table_##name	\
+		__used __section(__cpu_method_of_table)			\
+		= { .method = _method, .ops = _ops }
 /*
  * set platform specific SMP operations
  */
@@ -18,6 +18,7 @@
 #include <linux/of_fdt.h>
 #include <linux/of_irq.h>
 #include <linux/of_platform.h>
+#include <linux/smp.h>
  
 #include <asm/cputype.h>
 #include <asm/setup.h>
@@ -63,6 +64,34 @@
 	}
 }
  
+#ifdef CONFIG_SMP
+extern struct of_cpu_method __cpu_method_of_table_begin[];
+extern struct of_cpu_method __cpu_method_of_table_end[];
+
+static int __init set_smp_ops_by_method(struct device_node *node)
+{
+	const char *method;
+	struct of_cpu_method *m = __cpu_method_of_table_begin;
+
+	if (of_property_read_string(node, "enable-method", &method))
+		return 0;
+
+	for (; m < __cpu_method_of_table_end; m++)
+		if (!strcmp(m->method, method)) {
+			smp_set_ops(m->ops);
+			return 1;
+		}
+
+	return 0;
+}
+#else
+static inline int set_smp_ops_by_method(struct device_node *node)
+{
+	return 1;
+}
+#endif
+
+
 /*
  * 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
@@ -79,6 +108,7 @@
 	 * read as 0.
 	 */
 	struct device_node *cpu, *cpus;
+	int found_method = 0;
 	u32 i, j, cpuidx = 1;
 	u32 mpidr = is_smp() ? read_cpuid_mpidr() & MPIDR_HWID_BITMASK : 0;
  
  
@@ -150,7 +180,17 @@
 		}
  
 		tmp_map[i] = hwid;
+
+		if (!found_method)
+			found_method = set_smp_ops_by_method(cpu);
 	}
+
+	/*
+	 * Fallback to an enable-method in the cpus node if nothing found in
+	 * a cpu node.
+	 */
+	if (!found_method)
+		set_smp_ops_by_method(cpus);
  
 	if (!bootcpu_valid) {
 		pr_warn("DT missing boot CPU MPIDR[23:0], fall back to default cpu_logical_map\n");
@@ -167,6 +167,15 @@
 #define CLK_OF_TABLES()
 #endif
  
+#ifdef CONFIG_SMP
+#define CPU_METHOD_OF_TABLES() . = ALIGN(8);				    \
+			   VMLINUX_SYMBOL(__cpu_method_of_table_begin) = .; \
+			   *(__cpu_method_of_table)			    \
+			   VMLINUX_SYMBOL(__cpu_method_of_table_end) = .;
+#else
+#define CPU_METHOD_OF_TABLES()
+#endif
+
 #define KERNEL_DTB()							\
 	STRUCT_ALIGN();							\
 	VMLINUX_SYMBOL(__dtb_start) = .;				\
@@ -491,6 +500,7 @@
 	MEM_DISCARD(init.rodata)					\
 	CLK_OF_TABLES()							\
 	CLKSRC_OF_TABLES()						\
+	CPU_METHOD_OF_TABLES()						\
 	KERNEL_DTB()							\
 	IRQCHIP_OF_MATCH_TABLE()
...	...	@@ -114,6 +114,15 @@
114	114	#endif
115	115	};
116	116
	117	+struct of_cpu_method {
	118	+ const char *method;
	119	+ struct smp_operations *ops;
	120	+};
	121	+
	122	+#define CPU_METHOD_OF_DECLARE(name, _method, _ops) \
	123	+ static const struct of_cpu_method __cpu_method_of_table_##name \
	124	+ __used __section(__cpu_method_of_table) \
	125	+ = { .method = _method, .ops = _ops }
117	126	/*
118	127	* set platform specific SMP operations
119	128	*/
...	...	@@ -18,6 +18,7 @@
18	18	#include <linux/of_fdt.h>
19	19	#include <linux/of_irq.h>
20	20	#include <linux/of_platform.h>
	21	+#include <linux/smp.h>
21	22
22	23	#include <asm/cputype.h>
23	24	#include <asm/setup.h>
...	...	@@ -63,6 +64,34 @@
63	64	}
64	65	}
65	66
	67	+#ifdef CONFIG_SMP
	68	+extern struct of_cpu_method __cpu_method_of_table_begin[];
	69	+extern struct of_cpu_method __cpu_method_of_table_end[];
	70	+
	71	+static int __init set_smp_ops_by_method(struct device_node *node)
	72	+{
	73	+ const char *method;
	74	+ struct of_cpu_method *m = __cpu_method_of_table_begin;
	75	+
	76	+ if (of_property_read_string(node, "enable-method", &method))
	77	+ return 0;
	78	+
	79	+ for (; m < __cpu_method_of_table_end; m++)
	80	+ if (!strcmp(m->method, method)) {
	81	+ smp_set_ops(m->ops);
	82	+ return 1;
	83	+ }
	84	+
	85	+ return 0;
	86	+}
	87	+#else
	88	+static inline int set_smp_ops_by_method(struct device_node *node)
	89	+{
	90	+ return 1;
	91	+}
	92	+#endif
	93	+
	94	+
66	95	/*
67	96	* arm_dt_init_cpu_maps - Function retrieves cpu nodes from the device tree
68	97	* and builds the cpu logical map array containing MPIDR values related to
...	...	@@ -79,6 +108,7 @@
79	108	* read as 0.
80	109	*/
81	110	struct device_node cpu, cpus;
	111	+ int found_method = 0;
82	112	u32 i, j, cpuidx = 1;
83	113	u32 mpidr = is_smp() ? read_cpuid_mpidr() & MPIDR_HWID_BITMASK : 0;
84	114
85	115
...	...	@@ -150,7 +180,17 @@
150	180	}
151	181
152	182	tmp_map[i] = hwid;
	183	+
	184	+ if (!found_method)
	185	+ found_method = set_smp_ops_by_method(cpu);
153	186	}
	187	+
	188	+ /*
	189	+ * Fallback to an enable-method in the cpus node if nothing found in
	190	+ * a cpu node.
	191	+ */
	192	+ if (!found_method)
	193	+ set_smp_ops_by_method(cpus);
154	194
155	195	if (!bootcpu_valid) {
156	196	pr_warn("DT missing boot CPU MPIDR[23:0], fall back to default cpu_logical_map\n");
...	...	@@ -167,6 +167,15 @@
167	167	#define CLK_OF_TABLES()
168	168	#endif
169	169
	170	+#ifdef CONFIG_SMP
	171	+#define CPU_METHOD_OF_TABLES() . = ALIGN(8); \
	172	+ VMLINUX_SYMBOL(__cpu_method_of_table_begin) = .; \
	173	+ *(__cpu_method_of_table) \
	174	+ VMLINUX_SYMBOL(__cpu_method_of_table_end) = .;
	175	+#else
	176	+#define CPU_METHOD_OF_TABLES()
	177	+#endif
	178	+
170	179	#define KERNEL_DTB() \
171	180	STRUCT_ALIGN(); \
172	181	VMLINUX_SYMBOL(__dtb_start) = .; \
...	...	@@ -491,6 +500,7 @@
491	500	MEM_DISCARD(init.rodata) \
492	501	CLK_OF_TABLES() \
493	502	CLKSRC_OF_TABLES() \
	503	+ CPU_METHOD_OF_TABLES() \
494	504	KERNEL_DTB() \
495	505	IRQCHIP_OF_MATCH_TABLE()
496	506