| Message ID | 1387845593-10050-5-git-send-email-sboyd@codeaurora.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Dec 24, 2013 at 12:39:48AM +0000, Stephen Boyd wrote: > 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. Nice! > > Cc: 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> > --- > 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(+) > > diff --git a/arch/arm/include/asm/smp.h b/arch/arm/include/asm/smp.h > index 22a3b9b..772435b 100644 > --- 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 > */ > diff --git a/arch/arm/kernel/devtree.c b/arch/arm/kernel/devtree.c > index 739c3df..91cc3f8 100644 > --- a/arch/arm/kernel/devtree.c > +++ b/arch/arm/kernel/devtree.c > @@ -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 @@ 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 I was going to comment that this would look nicer using an error code or 0, rather than 0 or 1, but I see that would make the call sites more complicated / less legible. > + > + > /* > * 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; > diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h > index bc2121f..bd02ca7 100644 > --- a/include/asm-generic/vmlinux.lds.h > +++ b/include/asm-generic/vmlinux.lds.h > @@ -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 I suspect we'll use this on arm64 in future, where we might need this even on UP systems (for PSCI's cpu_suspend method). However, I think that can change that as and when we require it. > + > #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() Enthusiastically Acked-by: Mark Rutland <mark.rutland@arm.com> Cheers, Mark.
diff --git a/arch/arm/include/asm/smp.h b/arch/arm/include/asm/smp.h index 22a3b9b..772435b 100644 --- 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 */ diff --git a/arch/arm/kernel/devtree.c b/arch/arm/kernel/devtree.c index 739c3df..91cc3f8 100644 --- a/arch/arm/kernel/devtree.c +++ b/arch/arm/kernel/devtree.c @@ -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 @@ 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; diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index bc2121f..bd02ca7 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -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()
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. Cc: 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> --- 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(+)