From 48f17325fef9cbebc5cb39aa78f4c1caff5d7b16 Mon Sep 17 00:00:00 2001 From: Stephen Boyd Date: Wed, 30 Oct 2013 18:21:09 -0700 Subject: [PATCH 008/182] 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 Cc: Russell King Cc: Signed-off-by: Stephen Boyd Signed-off-by: Kumar Gala --- arch/arm/include/asm/smp.h | 9 +++++++++ arch/arm/kernel/devtree.c | 40 +++++++++++++++++++++++++++++++++++++ include/asm-generic/vmlinux.lds.h | 10 ++++++++++ 3 files changed, 59 insertions(+) --- a/arch/arm/include/asm/smp.h +++ b/arch/arm/include/asm/smp.h @@ -114,6 +114,15 @@ struct smp_operations { #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 */ --- a/arch/arm/kernel/devtree.c +++ b/arch/arm/kernel/devtree.c @@ -18,6 +18,7 @@ #include #include #include +#include #include #include @@ -63,6 +64,34 @@ void __init arm_dt_memblock_reserve(void } } +#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 @@ void __init arm_dt_init_cpu_maps(void) * 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; @@ -150,8 +180,18 @@ void __init arm_dt_init_cpu_maps(void) } 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"); return; --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -177,6 +177,15 @@ #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) = .; \ @@ -502,6 +511,7 @@ MEM_DISCARD(init.rodata) \ CLK_OF_TABLES() \ CLKSRC_OF_TABLES() \ + CPU_METHOD_OF_TABLES() \ KERNEL_DTB() \ IRQCHIP_OF_MATCH_TABLE()