| Message ID | 1383343739-23080-6-git-send-email-sboyd@codeaurora.org (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
On Nov 1, 2013, at 5:08 PM, 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. > > 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 | 38 ++++++++++++++++++++++++++++++++++++++ > include/asm-generic/vmlinux.lds.h | 10 ++++++++++ > 3 files changed, 57 insertions(+) > > diff --git a/arch/arm/include/asm/smp.h b/arch/arm/include/asm/smp.h > index a8cae71c..c27ec55 100644 > --- a/arch/arm/include/asm/smp.h > +++ b/arch/arm/include/asm/smp.h > @@ -112,6 +112,15 @@ 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 f35906b..71a8592 100644 > --- a/arch/arm/kernel/devtree.c > +++ b/arch/arm/kernel/devtree.c > @@ -25,6 +25,7 @@ > #include <asm/smp_plat.h> > #include <asm/mach/arch.h> > #include <asm/mach-types.h> > +#include <asm/smp.h> > > void __init early_init_dt_add_memory_arch(u64 base, u64 size) > { > @@ -63,6 +64,36 @@ void __init arm_dt_memblock_reserve(void) > } > } > > +#ifdef CONFIG_SMP > +extern struct of_cpu_method __cpu_method_of_table[]; > + > +static const struct of_cpu_method __cpu_method_of_table_sentinel > + __used __section(__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; > + > + if (of_property_read_string(node, "enable-method", &method)) > + return 0; > + > + for (; m != &__cpu_method_of_table_sentinel; 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 +110,7 @@ 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 +182,14 @@ void __init arm_dt_init_cpu_maps(void) > } > > tmp_map[i] = hwid; > + > + if (!found_method) > + found_method = set_smp_ops_by_method(cpu); > } > > + if (!found_method) > + set_smp_ops_by_method(cpus); > + I assume this if for the case that the enable method is in the cpus{ } container but not in a specific cpu node? If so, the binding is not clear that we allow this. Also a comment would probably be nice. > if (!bootcpu_valid) { > pr_warn("DT missing boot CPU MPIDR[23:0], fall back to default cpu_logical_map\n"); > return; - k
On 11/05/13 09:24, Kumar Gala wrote: > On Nov 1, 2013, at 5:08 PM, Stephen Boyd wrote: > >> @@ -150,8 +182,14 @@ void __init arm_dt_init_cpu_maps(void) >> } >> >> tmp_map[i] = hwid; >> + >> + if (!found_method) >> + found_method = set_smp_ops_by_method(cpu); >> } >> >> + if (!found_method) >> + set_smp_ops_by_method(cpus); >> + > I assume this if for the case that the enable method is in the cpus{ } container but not in a specific cpu node? > > If so, the binding is not clear that we allow this. Also a comment would probably be nice. Sure I'll add a comment to that effect and clarify the binding.
Hey Stephen- Nit/suggestion below: On Fri, Nov 01, 2013 at 03:08:53PM -0700, Stephen Boyd wrote: [..] > diff --git a/arch/arm/include/asm/smp.h b/arch/arm/include/asm/smp.h > index a8cae71c..c27ec55 100644 > --- a/arch/arm/include/asm/smp.h > +++ b/arch/arm/include/asm/smp.h > @@ -112,6 +112,15 @@ 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 f35906b..71a8592 100644 > --- a/arch/arm/kernel/devtree.c > +++ b/arch/arm/kernel/devtree.c > @@ -25,6 +25,7 @@ > #include <asm/smp_plat.h> > #include <asm/mach/arch.h> > #include <asm/mach-types.h> > +#include <asm/smp.h> > > void __init early_init_dt_add_memory_arch(u64 base, u64 size) > { > @@ -63,6 +64,36 @@ void __init arm_dt_memblock_reserve(void) > } > } > > +#ifdef CONFIG_SMP > +extern struct of_cpu_method __cpu_method_of_table[]; > + > +static const struct of_cpu_method __cpu_method_of_table_sentinel > + __used __section(__cpu_method_of_table_end); Having a sentinel allocated into the linked image makes a lot of sense in other cases (IRQCHIP/CLOCKSOURCE_OF_DECLARE, etc), where it's used to terminate an of_device_id table (as is expected by of_match_table and friends). In this case, however, you aren't building a match table, so having a sentinel allocated isn't necessary. I'd suggest bookending the table with a VMLINUX_SYMBOL(__cpu_method_of_table_end) instead. A whole 2 pointers worth of savings!
On 11/06/13 17:50, Josh Cartwright wrote: > On Fri, Nov 01, 2013 at 03:08:53PM -0700, Stephen Boyd wrote: >> diff --git a/arch/arm/kernel/devtree.c b/arch/arm/kernel/devtree.c >> index f35906b..71a8592 100644 >> --- a/arch/arm/kernel/devtree.c >> +++ b/arch/arm/kernel/devtree.c >> @@ -25,6 +25,7 @@ >> #include <asm/smp_plat.h> >> #include <asm/mach/arch.h> >> #include <asm/mach-types.h> >> +#include <asm/smp.h> >> >> void __init early_init_dt_add_memory_arch(u64 base, u64 size) >> { >> @@ -63,6 +64,36 @@ void __init arm_dt_memblock_reserve(void) >> } >> } >> >> +#ifdef CONFIG_SMP >> +extern struct of_cpu_method __cpu_method_of_table[]; >> + >> +static const struct of_cpu_method __cpu_method_of_table_sentinel >> + __used __section(__cpu_method_of_table_end); > Having a sentinel allocated into the linked image makes a lot of sense > in other cases (IRQCHIP/CLOCKSOURCE_OF_DECLARE, etc), where it's used to > terminate an of_device_id table (as is expected by of_match_table and > friends). > > In this case, however, you aren't building a match table, so having a > sentinel allocated isn't necessary. I'd suggest bookending the table > with a VMLINUX_SYMBOL(__cpu_method_of_table_end) instead. > > A whole 2 pointers worth of savings! > Yes, will do. Thanks.
diff --git a/arch/arm/include/asm/smp.h b/arch/arm/include/asm/smp.h index a8cae71c..c27ec55 100644 --- a/arch/arm/include/asm/smp.h +++ b/arch/arm/include/asm/smp.h @@ -112,6 +112,15 @@ 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 f35906b..71a8592 100644 --- a/arch/arm/kernel/devtree.c +++ b/arch/arm/kernel/devtree.c @@ -25,6 +25,7 @@ #include <asm/smp_plat.h> #include <asm/mach/arch.h> #include <asm/mach-types.h> +#include <asm/smp.h> void __init early_init_dt_add_memory_arch(u64 base, u64 size) { @@ -63,6 +64,36 @@ void __init arm_dt_memblock_reserve(void) } } +#ifdef CONFIG_SMP +extern struct of_cpu_method __cpu_method_of_table[]; + +static const struct of_cpu_method __cpu_method_of_table_sentinel + __used __section(__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; + + if (of_property_read_string(node, "enable-method", &method)) + return 0; + + for (; m != &__cpu_method_of_table_sentinel; 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 +110,7 @@ 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 +182,14 @@ void __init arm_dt_init_cpu_maps(void) } tmp_map[i] = hwid; + + if (!found_method) + found_method = set_smp_ops_by_method(cpu); } + 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 83e2c31..918b1b5 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) = .; \ + *(__cpu_method_of_table) \ + *(__cpu_method_of_table_end) +#else +#define CPU_METHOD_OF_TABLES() +#endif + #define KERNEL_DTB() \ STRUCT_ALIGN(); \ VMLINUX_SYMBOL(__dtb_start) = .; \ @@ -490,6 +499,7 @@ 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 | 38 ++++++++++++++++++++++++++++++++++++++ include/asm-generic/vmlinux.lds.h | 10 ++++++++++ 3 files changed, 57 insertions(+)