Messages in this thread Patch in this message | | | From | Atish Patra <> | Subject | [RFC PATCH 3/5] RISC-V: Add cpu_operatios structure | Date | Wed, 15 Aug 2018 16:56:15 -0700 |
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Defining cpu_operations now helps adding cpu hotplug support in proper manner. Moreover, it provides flexibility in supporting other cpu enable/boot methods can be supported in future. This patch has been largely inspired from ARM64. However, a default boot method is defined for RISC-V unlike ARM64.
Signed-off-by: Atish Patra <atish.patra@wdc.com> --- arch/riscv/include/asm/smp.h | 10 ++++++++++ arch/riscv/kernel/smp.c | 8 ++++++++ arch/riscv/kernel/smpboot.c | 34 ++++++++++++++++++++++++++++------ 3 files changed, 46 insertions(+), 6 deletions(-)
diff --git a/arch/riscv/include/asm/smp.h b/arch/riscv/include/asm/smp.h index 0763337b..2bb6e6c2 100644 --- a/arch/riscv/include/asm/smp.h +++ b/arch/riscv/include/asm/smp.h @@ -28,6 +28,15 @@ extern u64 __cpu_logical_map[NR_CPUS]; #define cpu_logical_map(cpu) __cpu_logical_map[cpu] +struct cpu_operations { + const char *name; + int (*cpu_init)(unsigned int); + int (*cpu_prepare)(unsigned int); + int (*cpu_boot)(unsigned int, struct task_struct *); +}; +extern struct cpu_operations cpu_ops; +void smp_set_cpu_ops(const struct cpu_operations *cpu_ops); + #ifdef CONFIG_SMP /* SMP initialization hook for setup_arch */ @@ -57,5 +66,6 @@ static inline void cpuid_to_hartid_mask(const struct cpumask *in, cpumask_set_cpu(cpu_logical_map(0), out); } + #endif /* CONFIG_SMP */ #endif /* _ASM_RISCV_SMP_H */ diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c index 4ab70480..5de58ced 100644 --- a/arch/riscv/kernel/smp.c +++ b/arch/riscv/kernel/smp.c @@ -58,6 +58,14 @@ void cpuid_to_hartid_mask(const struct cpumask *in, struct cpumask *out) for_each_cpu(cpu, in) cpumask_set_cpu(cpu_logical_map(cpu), out); } +struct cpu_operations cpu_ops __ro_after_init; + +void smp_set_cpu_ops(const struct cpu_operations *ops) +{ + if (ops) + cpu_ops = *ops; +} + /* Unsupported */ int setup_profiling_timer(unsigned int multiplier) { diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c index 6ab2bb1b..045a1a45 100644 --- a/arch/riscv/kernel/smpboot.c +++ b/arch/riscv/kernel/smpboot.c @@ -30,6 +30,7 @@ #include <linux/irq.h> #include <linux/of.h> #include <linux/sched/task_stack.h> +#include <linux/smp.h> #include <asm/irq.h> #include <asm/mmu_context.h> #include <asm/tlbflush.h> @@ -38,6 +39,7 @@ void *__cpu_up_stack_pointer[NR_CPUS]; void *__cpu_up_task_pointer[NR_CPUS]; +struct cpu_operations default_ops; void __init smp_prepare_boot_cpu(void) { @@ -53,6 +55,7 @@ void __init setup_smp(void) int hart, found_boot_cpu = 0; int cpuid = 1; + smp_set_cpu_ops(&default_ops); while ((dn = of_find_node_by_type(dn, "cpu"))) { hart = riscv_of_processor_hart(dn); @@ -73,10 +76,8 @@ void __init setup_smp(void) BUG_ON(!found_boot_cpu); } -int __cpu_up(unsigned int cpu, struct task_struct *tidle) +int default_cpu_boot(unsigned int hartid, struct task_struct *tidle) { - int hartid = cpu_logical_map(cpu); - tidle->thread_info.cpu = cpu; /* * On RISC-V systems, all harts boot on their own accord. Our _start * selects the first hart to boot the kernel and causes the remainder @@ -84,13 +85,28 @@ int __cpu_up(unsigned int cpu, struct task_struct *tidle) * setup by that main hart. Writing __cpu_up_stack_pointer signals to * the spinning harts that they can continue the boot process. */ - smp_mb(); + __cpu_up_stack_pointer[hartid] = task_stack_page(tidle) + THREAD_SIZE; __cpu_up_task_pointer[hartid] = tidle; + return 0; +} + +int __cpu_up(unsigned int cpu, struct task_struct *tidle) +{ + int err = -1; + int hartid = cpu_logical_map(cpu); - while (!cpu_online(cpu)) - cpu_relax(); + tidle->thread_info.cpu = cpu; + smp_mb(); + if (cpu_ops.cpu_boot) + err = cpu_ops.cpu_boot(hartid, tidle); + if (!err) { + while (!cpu_online(cpu)) + cpu_relax(); + } else { + pr_err("CPU %d [hartid %d]failed to boot\n", cpu, hartid); + } return 0; } @@ -117,3 +133,9 @@ asmlinkage void __init smp_callin(void) preempt_disable(); cpu_startup_entry(CPUHP_AP_ONLINE_IDLE); } + + +struct cpu_operations default_ops = { + .name = "default", + .cpu_boot = default_cpu_boot, +}; -- 2.7.4
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