diff options
| -rw-r--r-- | arch/mips/Kconfig | 13 | ||||
| -rw-r--r-- | arch/mips/kernel/i8259.c | 3 | ||||
| -rw-r--r-- | arch/mips/kernel/smtc.c | 63 | ||||
| -rw-r--r-- | arch/mips/mips-boards/malta/malta_smtc.c | 50 | ||||
| -rw-r--r-- | include/asm-mips/irq.h | 67 | ||||
| -rw-r--r-- | include/asm-mips/smtc_ipi.h | 1 |
6 files changed, 195 insertions, 2 deletions
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index 3b807b4..b09eee2 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -1378,6 +1378,19 @@ config MIPS_MT_SMTC_IM_BACKSTOP impact on interrupt service overhead. Disable it only if you know what you are doing. +config MIPS_MT_SMTC_IRQAFF + bool "Support IRQ affinity API" + depends on MIPS_MT_SMTC + default n + help + Enables SMP IRQ affinity API (/proc/irq/*/smp_affinity, etc.) + for SMTC Linux kernel. Requires platform support, of which + an example can be found in the MIPS kernel i8259 and Malta + platform code. It is recommended that MIPS_MT_SMTC_INSTANT_REPLAY + be enabled if MIPS_MT_SMTC_IRQAFF is used. Adds overhead to + interrupt dispatch, and should be used only if you know what + you are doing. + config MIPS_VPE_LOADER_TOM bool "Load VPE program into memory hidden from linux" depends on MIPS_VPE_LOADER diff --git a/arch/mips/kernel/i8259.c b/arch/mips/kernel/i8259.c index 3a2d255..4f4359b 100644 --- a/arch/mips/kernel/i8259.c +++ b/arch/mips/kernel/i8259.c @@ -39,6 +39,9 @@ static struct irq_chip i8259A_chip = { .disable = disable_8259A_irq, .unmask = enable_8259A_irq, .mask_ack = mask_and_ack_8259A, +#ifdef CONFIG_MIPS_MT_SMTC_IRQAFF + .set_affinity = plat_set_irq_affinity, +#endif /* CONFIG_MIPS_MT_SMTC_IRQAFF */ }; /* diff --git a/arch/mips/kernel/smtc.c b/arch/mips/kernel/smtc.c index f094043..fe22387 100644 --- a/arch/mips/kernel/smtc.c +++ b/arch/mips/kernel/smtc.c @@ -606,6 +606,60 @@ int setup_irq_smtc(unsigned int irq, struct irqaction * new, return setup_irq(irq, new); } +#ifdef CONFIG_MIPS_MT_SMTC_IRQAFF +/* + * Support for IRQ affinity to TCs + */ + +void smtc_set_irq_affinity(unsigned int irq, cpumask_t affinity) +{ + /* + * If a "fast path" cache of quickly decodable affinity state + * is maintained, this is where it gets done, on a call up + * from the platform affinity code. + */ +} + +void smtc_forward_irq(unsigned int irq) +{ + int target; + + /* + * OK wise guy, now figure out how to get the IRQ + * to be serviced on an authorized "CPU". + * + * Ideally, to handle the situation where an IRQ has multiple + * eligible CPUS, we would maintain state per IRQ that would + * allow a fair distribution of service requests. Since the + * expected use model is any-or-only-one, for simplicity + * and efficiency, we just pick the easiest one to find. + */ + + target = first_cpu(irq_desc[irq].affinity); + + /* + * We depend on the platform code to have correctly processed + * IRQ affinity change requests to ensure that the IRQ affinity + * mask has been purged of bits corresponding to nonexistent and + * offline "CPUs", and to TCs bound to VPEs other than the VPE + * connected to the physical interrupt input for the interrupt + * in question. Otherwise we have a nasty problem with interrupt + * mask management. This is best handled in non-performance-critical + * platform IRQ affinity setting code, to minimize interrupt-time + * checks. + */ + + /* If no one is eligible, service locally */ + if (target >= NR_CPUS) { + do_IRQ_no_affinity(irq); + return; + } + + smtc_send_ipi(target, IRQ_AFFINITY_IPI, irq); +} + +#endif /* CONFIG_MIPS_MT_SMTC_IRQAFF */ + /* * IPI model for SMTC is tricky, because interrupts aren't TC-specific. * Within a VPE one TC can interrupt another by different approaches. @@ -830,6 +884,15 @@ void ipi_decode(struct smtc_ipi *pipi) break; } break; +#ifdef CONFIG_MIPS_MT_SMTC_IRQAFF + case IRQ_AFFINITY_IPI: + /* + * Accept a "forwarded" interrupt that was initially + * taken by a TC who doesn't have affinity for the IRQ. + */ + do_IRQ_no_affinity((int)arg_copy); + break; +#endif /* CONFIG_MIPS_MT_SMTC_IRQAFF */ default: printk("Impossible SMTC IPI Type 0x%x\n", type_copy); break; diff --git a/arch/mips/mips-boards/malta/malta_smtc.c b/arch/mips/mips-boards/malta/malta_smtc.c index ae05d05..5c980f4 100644 --- a/arch/mips/mips-boards/malta/malta_smtc.c +++ b/arch/mips/mips-boards/malta/malta_smtc.c @@ -88,3 +88,53 @@ void __cpuinit prom_smp_finish(void) void prom_cpus_done(void) { } + +#ifdef CONFIG_MIPS_MT_SMTC_IRQAFF +/* + * IRQ affinity hook + */ + + +void plat_set_irq_affinity(unsigned int irq, cpumask_t affinity) +{ + cpumask_t tmask = affinity; + int cpu = 0; + void smtc_set_irq_affinity(unsigned int irq, cpumask_t aff); + + /* + * On the legacy Malta development board, all I/O interrupts + * are routed through the 8259 and combined in a single signal + * to the CPU daughterboard, and on the CoreFPGA2/3 34K models, + * that signal is brought to IP2 of both VPEs. To avoid racing + * concurrent interrupt service events, IP2 is enabled only on + * one VPE, by convention VPE0. So long as no bits are ever + * cleared in the affinity mask, there will never be any + * interrupt forwarding. But as soon as a program or operator + * sets affinity for one of the related IRQs, we need to make + * sure that we don't ever try to forward across the VPE boundry, + * at least not until we engineer a system where the interrupt + * _ack() or _end() function can somehow know that it corresponds + * to an interrupt taken on another VPE, and perform the appropriate + * restoration of Status.IM state using MFTR/MTTR instead of the + * normal local behavior. We also ensure that no attempt will + * be made to forward to an offline "CPU". + */ + + for_each_cpu_mask(cpu, affinity) { + if ((cpu_data[cpu].vpe_id != 0) || !cpu_online(cpu)) + cpu_clear(cpu, tmask); + } + irq_desc[irq].affinity = tmask; + + if (cpus_empty(tmask)) + /* + * We could restore a default mask here, but the + * runtime code can anyway deal with the null set + */ + printk(KERN_WARNING + "IRQ affinity leaves no legal CPU for IRQ %d\n", irq); + + /* Do any generic SMTC IRQ affinity setup */ + smtc_set_irq_affinity(irq, tmask); +} +#endif /* CONFIG_MIPS_MT_SMTC_IRQAFF */ diff --git a/include/asm-mips/irq.h b/include/asm-mips/irq.h index 2cb52cf..a58f0ee 100644 --- a/include/asm-mips/irq.h +++ b/include/asm-mips/irq.h @@ -46,6 +46,38 @@ static inline void smtc_im_ack_irq(unsigned int irq) #endif /* CONFIG_MIPS_MT_SMTC */ +#ifdef CONFIG_MIPS_MT_SMTC_IRQAFF +#include <linux/cpumask.h> + +extern void plat_set_irq_affinity(unsigned int irq, cpumask_t affinity); +extern void smtc_forward_irq(unsigned int irq); + +/* + * IRQ affinity hook invoked at the beginning of interrupt dispatch + * if option is enabled. + * + * Up through Linux 2.6.22 (at least) cpumask operations are very + * inefficient on MIPS. Initial prototypes of SMTC IRQ affinity + * used a "fast path" per-IRQ-descriptor cache of affinity information + * to reduce latency. As there is a project afoot to optimize the + * cpumask implementations, this version is optimistically assuming + * that cpumask.h macro overhead is reasonable during interrupt dispatch. + */ +#define IRQ_AFFINITY_HOOK(irq) \ +do { \ + if (!cpu_isset(smp_processor_id(), irq_desc[irq].affinity)) { \ + smtc_forward_irq(irq); \ + irq_exit(); \ + return; \ + } \ +} while (0) + +#else /* Not doing SMTC affinity */ + +#define IRQ_AFFINITY_HOOK(irq) do { } while (0) + +#endif /* CONFIG_MIPS_MT_SMTC_IRQAFF */ + #ifdef CONFIG_MIPS_MT_SMTC_IM_BACKSTOP /* @@ -56,13 +88,27 @@ static inline void smtc_im_ack_irq(unsigned int irq) */ #define __DO_IRQ_SMTC_HOOK(irq) \ do { \ + IRQ_AFFINITY_HOOK(irq); \ if (irq_hwmask[irq] & 0x0000ff00) \ write_c0_tccontext(read_c0_tccontext() & \ - ~(irq_hwmask[irq] & 0x0000ff00)); \ + ~(irq_hwmask[irq] & 0x0000ff00)); \ +} while (0) + +#define __NO_AFFINITY_IRQ_SMTC_HOOK(irq) \ +do { \ + if (irq_hwmask[irq] & 0x0000ff00) \ + write_c0_tccontext(read_c0_tccontext() & \ + ~(irq_hwmask[irq] & 0x0000ff00)); \ } while (0) + #else -#define __DO_IRQ_SMTC_HOOK(irq) do { } while (0) +#define __DO_IRQ_SMTC_HOOK(irq) \ +do { \ + IRQ_AFFINITY_HOOK(irq); \ +} while (0) +#define __NO_AFFINITY_IRQ_SMTC_HOOK(irq) do { } while (0) + #endif /* @@ -81,6 +127,23 @@ do { \ irq_exit(); \ } while (0) +#ifdef CONFIG_MIPS_MT_SMTC_IRQAFF +/* + * To avoid inefficient and in some cases pathological re-checking of + * IRQ affinity, we have this variant that skips the affinity check. + */ + + +#define do_IRQ_no_affinity(irq) \ +do { \ + irq_enter(); \ + __NO_AFFINITY_IRQ_SMTC_HOOK(irq); \ + generic_handle_irq(irq); \ + irq_exit(); \ +} while (0) + +#endif /* CONFIG_MIPS_MT_SMTC_IRQAFF */ + extern void arch_init_irq(void); extern void spurious_interrupt(void); diff --git a/include/asm-mips/smtc_ipi.h b/include/asm-mips/smtc_ipi.h index a52a4a7..e09131a 100644 --- a/include/asm-mips/smtc_ipi.h +++ b/include/asm-mips/smtc_ipi.h @@ -34,6 +34,7 @@ struct smtc_ipi { #define LINUX_SMP_IPI 1 #define SMTC_CLOCK_TICK 2 +#define IRQ_AFFINITY_IPI 3 /* * A queue of IPI messages |
