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Subject[PATCH v3 23/44] metag: IRQ handling
Date
Add core IRQ handling for metag. The code in irq.c exposes the TBX
signal numbers as Linux IRQs.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
---
arch/metag/include/asm/irq.h | 32 ++++
arch/metag/include/asm/irqflags.h | 97 +++++++++++
arch/metag/kernel/irq.c | 317 +++++++++++++++++++++++++++++++++++++
3 files changed, 446 insertions(+), 0 deletions(-)
create mode 100644 arch/metag/include/asm/irq.h
create mode 100644 arch/metag/include/asm/irqflags.h
create mode 100644 arch/metag/kernel/irq.c

diff --git a/arch/metag/include/asm/irq.h b/arch/metag/include/asm/irq.h
new file mode 100644
index 0000000..be0c8f3
--- /dev/null
+++ b/arch/metag/include/asm/irq.h
@@ -0,0 +1,32 @@
+#ifndef __ASM_METAG_IRQ_H
+#define __ASM_METAG_IRQ_H
+
+#ifdef CONFIG_4KSTACKS
+extern void irq_ctx_init(int cpu);
+extern void irq_ctx_exit(int cpu);
+# define __ARCH_HAS_DO_SOFTIRQ
+#else
+# define irq_ctx_init(cpu) do { } while (0)
+# define irq_ctx_exit(cpu) do { } while (0)
+#endif
+
+void tbi_startup_interrupt(int);
+void tbi_shutdown_interrupt(int);
+
+struct pt_regs;
+
+int tbisig_map(unsigned int hw);
+extern void do_IRQ(int irq, struct pt_regs *regs);
+
+#ifdef CONFIG_METAG_SUSPEND_MEM
+int traps_save_context(void);
+int traps_restore_context(void);
+#endif
+
+#include <asm-generic/irq.h>
+
+#ifdef CONFIG_HOTPLUG_CPU
+extern void migrate_irqs(void);
+#endif
+
+#endif /* __ASM_METAG_IRQ_H */
diff --git a/arch/metag/include/asm/irqflags.h b/arch/metag/include/asm/irqflags.h
new file mode 100644
index 0000000..ab5df87
--- /dev/null
+++ b/arch/metag/include/asm/irqflags.h
@@ -0,0 +1,97 @@
+/*
+ * IRQ flags handling
+ *
+ * This file gets included from lowlevel asm headers too, to provide
+ * wrapped versions of the local_irq_*() APIs, based on the
+ * raw_local_irq_*() functions from the lowlevel headers.
+ */
+#ifndef _ASM_IRQFLAGS_H
+#define _ASM_IRQFLAGS_H
+
+#ifndef __ASSEMBLY__
+
+#include <asm/metag_regs.h>
+
+#define INTS_OFF_MASK TXSTATI_BGNDHALT_BIT
+
+#ifdef CONFIG_SMP
+extern unsigned int get_trigger_mask(void);
+#else
+
+extern unsigned int global_trigger_mask;
+
+static inline unsigned int get_trigger_mask(void)
+{
+ return global_trigger_mask;
+}
+#endif
+
+static inline unsigned long arch_local_save_flags(void)
+{
+ unsigned long flags;
+
+ asm volatile("MOV %0,TXMASKI\n" : "=r" (flags));
+
+ return flags;
+}
+
+static inline int arch_irqs_disabled_flags(unsigned long flags)
+{
+ return (flags & ~INTS_OFF_MASK) == 0;
+}
+
+static inline int arch_irqs_disabled(void)
+{
+ unsigned long flags = arch_local_save_flags();
+
+ return arch_irqs_disabled_flags(flags);
+}
+
+static inline unsigned long __irqs_disabled(void)
+{
+ /*
+ * We shouldn't enable exceptions if they are not already
+ * enabled. This is required for chancalls to work correctly.
+ */
+ return arch_local_save_flags() & INTS_OFF_MASK;
+}
+
+/*
+ * For spinlocks, etc:
+ */
+static inline unsigned long arch_local_irq_save(void)
+{
+ unsigned long flags = __irqs_disabled();
+
+ asm volatile("SWAP %0,TXMASKI\n" : "=r" (flags) : "0" (flags)
+ : "memory");
+
+ return flags;
+}
+
+static inline void arch_local_irq_restore(unsigned long flags)
+{
+ asm volatile("MOV TXMASKI,%0\n" : : "r" (flags) : "memory");
+}
+
+static inline void arch_local_irq_disable(void)
+{
+ unsigned long flags = __irqs_disabled();
+
+ asm volatile("MOV TXMASKI,%0\n" : : "r" (flags) : "memory");
+}
+
+static inline void arch_local_irq_enable(void)
+{
+#ifdef CONFIG_SMP
+ preempt_disable();
+ arch_local_irq_restore(get_trigger_mask());
+ preempt_enable_no_resched();
+#else
+ arch_local_irq_restore(get_trigger_mask());
+#endif
+}
+
+#endif /* (__ASSEMBLY__) */
+
+#endif /* !(_ASM_IRQFLAGS_H) */
diff --git a/arch/metag/kernel/irq.c b/arch/metag/kernel/irq.c
new file mode 100644
index 0000000..769bd74
--- /dev/null
+++ b/arch/metag/kernel/irq.c
@@ -0,0 +1,317 @@
+/*
+ * Linux/Meta general interrupt handling code
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/irqdomain.h>
+#include <linux/ratelimit.h>
+
+#include <asm/mach/arch.h>
+#include <asm/uaccess.h>
+
+#ifdef CONFIG_4KSTACKS
+union irq_ctx {
+ struct thread_info tinfo;
+ u32 stack[THREAD_SIZE/sizeof(u32)];
+};
+
+static union irq_ctx *hardirq_ctx[NR_CPUS] __read_mostly;
+static union irq_ctx *softirq_ctx[NR_CPUS] __read_mostly;
+#endif
+
+struct irq_domain *root_domain;
+
+static unsigned int startup_meta_irq(struct irq_data *data)
+{
+ tbi_startup_interrupt(data->hwirq);
+ return 0;
+}
+
+static void shutdown_meta_irq(struct irq_data *data)
+{
+ tbi_shutdown_interrupt(data->hwirq);
+}
+
+void do_IRQ(int irq, struct pt_regs *regs)
+{
+ struct pt_regs *old_regs = set_irq_regs(regs);
+#ifdef CONFIG_4KSTACKS
+ struct irq_desc *desc;
+ union irq_ctx *curctx, *irqctx;
+ u32 *isp;
+#endif
+
+ irq_enter();
+
+ irq = irq_linear_revmap(root_domain, irq);
+
+#ifdef CONFIG_DEBUG_STACKOVERFLOW
+ /* Debugging check for stack overflow: is there less than 1KB free? */
+ {
+ unsigned long sp;
+
+ asm volatile ("MOV %0,A0StP\n" : "=r"(sp));
+ sp &= THREAD_SIZE - 1;
+
+ if (unlikely(sp > (THREAD_SIZE - 1024)))
+ pr_err("Stack overflow in do_IRQ: %ld\n", sp);
+ }
+#endif
+
+
+#ifdef CONFIG_4KSTACKS
+ curctx = (union irq_ctx *) current_thread_info();
+ irqctx = hardirq_ctx[smp_processor_id()];
+
+ /*
+ * this is where we switch to the IRQ stack. However, if we are
+ * already using the IRQ stack (because we interrupted a hardirq
+ * handler) we can't do that and just have to keep using the
+ * current stack (which is the irq stack already after all)
+ */
+ if (curctx != irqctx) {
+ /* build the stack frame on the IRQ stack */
+ isp = (u32 *) ((char *)irqctx + sizeof(struct thread_info));
+ irqctx->tinfo.task = curctx->tinfo.task;
+
+ /*
+ * Copy the softirq bits in preempt_count so that the
+ * softirq checks work in the hardirq context.
+ */
+ irqctx->tinfo.preempt_count =
+ (irqctx->tinfo.preempt_count & ~SOFTIRQ_MASK) |
+ (curctx->tinfo.preempt_count & SOFTIRQ_MASK);
+
+ desc = irq_to_desc(irq);
+
+ asm volatile (
+ "MOV D0.5,%0\n"
+ "MOV D1Ar1,%1\n"
+ "MOV D1RtP,%2\n"
+ "MOV D0Ar2,%3\n"
+ "SWAP A0StP,D0.5\n"
+ "SWAP PC,D1RtP\n"
+ "MOV A0StP,D0.5\n"
+ :
+ : "r" (isp), "r" (irq), "r" (desc->handle_irq),
+ "r" (desc)
+ : "memory", "cc", "D1Ar1", "D0Ar2", "D1Ar3", "D0Ar4",
+ "D1Ar5", "D0Ar6", "D0Re0", "D1Re0", "D0.4", "D1RtP",
+ "D0.5"
+ );
+ } else
+#endif
+ generic_handle_irq(irq);
+
+ irq_exit();
+
+ set_irq_regs(old_regs);
+}
+
+#ifdef CONFIG_4KSTACKS
+
+static char softirq_stack[NR_CPUS * THREAD_SIZE] __page_aligned_bss;
+
+static char hardirq_stack[NR_CPUS * THREAD_SIZE] __page_aligned_bss;
+
+/*
+ * allocate per-cpu stacks for hardirq and for softirq processing
+ */
+void irq_ctx_init(int cpu)
+{
+ union irq_ctx *irqctx;
+
+ if (hardirq_ctx[cpu])
+ return;
+
+ irqctx = (union irq_ctx *) &hardirq_stack[cpu * THREAD_SIZE];
+ irqctx->tinfo.task = NULL;
+ irqctx->tinfo.exec_domain = NULL;
+ irqctx->tinfo.cpu = cpu;
+ irqctx->tinfo.preempt_count = HARDIRQ_OFFSET;
+ irqctx->tinfo.addr_limit = MAKE_MM_SEG(0);
+
+ hardirq_ctx[cpu] = irqctx;
+
+ irqctx = (union irq_ctx *) &softirq_stack[cpu * THREAD_SIZE];
+ irqctx->tinfo.task = NULL;
+ irqctx->tinfo.exec_domain = NULL;
+ irqctx->tinfo.cpu = cpu;
+ irqctx->tinfo.preempt_count = 0;
+ irqctx->tinfo.addr_limit = MAKE_MM_SEG(0);
+
+ softirq_ctx[cpu] = irqctx;
+
+ pr_info("CPU %u irqstacks, hard=%p soft=%p\n",
+ cpu, hardirq_ctx[cpu], softirq_ctx[cpu]);
+}
+
+void irq_ctx_exit(int cpu)
+{
+ hardirq_ctx[smp_processor_id()] = NULL;
+}
+
+extern asmlinkage void __do_softirq(void);
+
+asmlinkage void do_softirq(void)
+{
+ unsigned long flags;
+ struct thread_info *curctx;
+ union irq_ctx *irqctx;
+ u32 *isp;
+
+ if (in_interrupt())
+ return;
+
+ local_irq_save(flags);
+
+ if (local_softirq_pending()) {
+ curctx = current_thread_info();
+ irqctx = softirq_ctx[smp_processor_id()];
+ irqctx->tinfo.task = curctx->task;
+
+ /* build the stack frame on the softirq stack */
+ isp = (u32 *) ((char *)irqctx + sizeof(struct thread_info));
+
+ asm volatile (
+ "MOV D0.5,%0\n"
+ "SWAP A0StP,D0.5\n"
+ "CALLR D1RtP,___do_softirq\n"
+ "MOV A0StP,D0.5\n"
+ :
+ : "r" (isp)
+ : "memory", "cc", "D1Ar1", "D0Ar2", "D1Ar3", "D0Ar4",
+ "D1Ar5", "D0Ar6", "D0Re0", "D1Re0", "D0.4", "D1RtP",
+ "D0.5"
+ );
+ /*
+ * Shouldn't happen, we returned above if in_interrupt():
+ */
+ WARN_ON_ONCE(softirq_count());
+ }
+
+ local_irq_restore(flags);
+}
+#endif
+
+static struct irq_chip meta_irq_type = {
+ .name = "META-IRQ",
+ .irq_startup = startup_meta_irq,
+ .irq_shutdown = shutdown_meta_irq,
+};
+
+/**
+ * tbisig_map() - Map a TBI signal number to a virtual IRQ number.
+ * @hw: Number of the TBI signal. Must be in range.
+ *
+ * Returns: The virtual IRQ number of the TBI signal number IRQ specified by
+ * @hw.
+ */
+int tbisig_map(unsigned int hw)
+{
+ return irq_create_mapping(root_domain, hw);
+}
+
+/**
+ * metag_tbisig_map() - map a tbi signal to a Linux virtual IRQ number
+ * @d: root irq domain
+ * @irq: virtual irq number
+ * @hw: hardware irq number (TBI signal number)
+ *
+ * This sets up a virtual irq for a specified TBI signal number.
+ */
+static int metag_tbisig_map(struct irq_domain *d, unsigned int irq,
+ irq_hw_number_t hw)
+{
+#ifdef CONFIG_SMP
+ irq_set_chip_and_handler(irq, &meta_irq_type, handle_percpu_irq);
+#else
+ irq_set_chip_and_handler(irq, &meta_irq_type, handle_simple_irq);
+#endif
+ return 0;
+}
+
+static const struct irq_domain_ops metag_tbisig_domain_ops = {
+ .map = metag_tbisig_map,
+};
+
+/*
+ * void init_IRQ(void)
+ *
+ * Parameters: None
+ *
+ * Returns: Nothing
+ *
+ * This function should be called during kernel startup to initialize
+ * the IRQ handling routines.
+ */
+void __init init_IRQ(void)
+{
+ root_domain = irq_domain_add_linear(NULL, 32,
+ &metag_tbisig_domain_ops, NULL);
+ if (unlikely(!root_domain))
+ panic("init_IRQ: cannot add root IRQ domain");
+
+ irq_ctx_init(smp_processor_id());
+
+ if (machine_desc->init_irq)
+ machine_desc->init_irq();
+}
+
+int __init arch_probe_nr_irqs(void)
+{
+ if (machine_desc->nr_irqs)
+ nr_irqs = machine_desc->nr_irqs;
+ return 0;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+static void route_irq(struct irq_data *data, unsigned int irq, unsigned int cpu)
+{
+ struct irq_desc *desc = irq_to_desc(irq);
+ struct irq_chip *chip = irq_data_get_irq_chip(data);
+
+ raw_spin_lock_irq(&desc->lock);
+ if (chip->irq_set_affinity)
+ chip->irq_set_affinity(data, cpumask_of(cpu), false);
+ raw_spin_unlock_irq(&desc->lock);
+}
+
+/*
+ * The CPU has been marked offline. Migrate IRQs off this CPU. If
+ * the affinity settings do not allow other CPUs, force them onto any
+ * available CPU.
+ */
+void migrate_irqs(void)
+{
+ unsigned int i, cpu = smp_processor_id();
+ struct irq_desc *desc;
+
+ for_each_irq_desc(i, desc) {
+ struct irq_data *data = irq_desc_get_irq_data(desc);
+ unsigned int newcpu;
+
+ if (irqd_is_per_cpu(data))
+ continue;
+
+ if (!cpumask_test_cpu(cpu, data->affinity))
+ continue;
+
+ newcpu = cpumask_any_and(data->affinity, cpu_online_mask);
+
+ if (newcpu >= nr_cpu_ids) {
+ pr_info_ratelimited("IRQ%u no longer affine to CPU%u\n",
+ i, cpu);
+
+ cpumask_setall(data->affinity);
+ newcpu = cpumask_any_and(data->affinity,
+ cpu_online_mask);
+ }
+
+ route_irq(data, i, newcpu);
+ }
+}
+#endif /* CONFIG_HOTPLUG_CPU */
--
1.7.7.6



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