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>
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@ -114,6 +114,15 @@ struct smp_operations {
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#endif
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};
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struct of_cpu_method {
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const char *method;
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struct smp_operations *ops;
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};
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#define CPU_METHOD_OF_DECLARE(name, _method, _ops) \
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static const struct of_cpu_method __cpu_method_of_table_##name \
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__used __section(__cpu_method_of_table) \
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= { .method = _method, .ops = _ops }
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/*
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* set platform specific SMP operations
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*/
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@ -18,6 +18,7 @@
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#include <linux/of_fdt.h>
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#include <linux/of_irq.h>
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#include <linux/of_platform.h>
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#include <linux/smp.h>
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#include <asm/cputype.h>
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#include <asm/setup.h>
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@ -63,6 +64,34 @@ void __init arm_dt_memblock_reserve(void)
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}
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}
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#ifdef CONFIG_SMP
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extern struct of_cpu_method __cpu_method_of_table_begin[];
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extern struct of_cpu_method __cpu_method_of_table_end[];
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static int __init set_smp_ops_by_method(struct device_node *node)
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{
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const char *method;
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struct of_cpu_method *m = __cpu_method_of_table_begin;
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if (of_property_read_string(node, "enable-method", &method))
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return 0;
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for (; m < __cpu_method_of_table_end; m++)
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if (!strcmp(m->method, method)) {
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smp_set_ops(m->ops);
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return 1;
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}
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return 0;
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}
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#else
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static inline int set_smp_ops_by_method(struct device_node *node)
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{
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return 1;
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}
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#endif
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/*
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* arm_dt_init_cpu_maps - Function retrieves cpu nodes from the device tree
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* and builds the cpu logical map array containing MPIDR values related to
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@ -79,6 +108,7 @@ void __init arm_dt_init_cpu_maps(void)
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* read as 0.
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*/
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struct device_node *cpu, *cpus;
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int found_method = 0;
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u32 i, j, cpuidx = 1;
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u32 mpidr = is_smp() ? read_cpuid_mpidr() & MPIDR_HWID_BITMASK : 0;
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@ -150,8 +180,18 @@ void __init arm_dt_init_cpu_maps(void)
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}
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tmp_map[i] = hwid;
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if (!found_method)
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found_method = set_smp_ops_by_method(cpu);
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}
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/*
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* Fallback to an enable-method in the cpus node if nothing found in
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* a cpu node.
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*/
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if (!found_method)
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set_smp_ops_by_method(cpus);
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if (!bootcpu_valid) {
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pr_warn("DT missing boot CPU MPIDR[23:0], fall back to default cpu_logical_map\n");
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return;
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@ -167,6 +167,15 @@
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#define CLK_OF_TABLES()
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#endif
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#ifdef CONFIG_SMP
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#define CPU_METHOD_OF_TABLES() . = ALIGN(8); \
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VMLINUX_SYMBOL(__cpu_method_of_table_begin) = .; \
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*(__cpu_method_of_table) \
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VMLINUX_SYMBOL(__cpu_method_of_table_end) = .;
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#else
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#define CPU_METHOD_OF_TABLES()
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#endif
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#define KERNEL_DTB() \
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STRUCT_ALIGN(); \
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VMLINUX_SYMBOL(__dtb_start) = .; \
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@ -491,6 +500,7 @@
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MEM_DISCARD(init.rodata) \
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CLK_OF_TABLES() \
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CLKSRC_OF_TABLES() \
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CPU_METHOD_OF_TABLES() \
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KERNEL_DTB() \
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IRQCHIP_OF_MATCH_TABLE()
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