genirq: handling GIC per-cpu interrupts

PATCH Superseded Marc Zyngier 3 participants 10 messages Oct 3, 2011 – Oct 20, 2011

Subsystems (6)

Arm (32-bit) Arm sub-architectures Arm Samsung Exynos Arm/RISC-V/Renesas architecture +2 more subsystems

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Marc Zyngier

author

2011-10-03 17:04 UTC #0 lore raw

v4 cover genirq: handling GIC per-cpu interrupts

The current GIC per-cpu interrupts (aka PPIs) suffer from a number of problems:

- They use a completely separate scheme to handle the interrupts, mostly because the PPI concept doesn't really match the kernel view of an interrupt.
- PPIs can only be used by the timer code, unless we add more low-level assembly code.
- The local timer code can only be used by devices generating PPIs, and not SPIs.
- At least one platform (msm) has started implementing its own alternative scheme.
- Some low-level code gets duplicated, as usual...

The proposed solution is to handle the PPIs using the same path as SPIs. A new core API is added to deal with per-cpu interrupts in a less awkward way. The local timer code is updated to reflect these changes.

The core API changes are based on an initial idea by Thomas Gleixner.

Tested on ARM Versatile Express (Cortex A15), ARM RealView PB11MP, OMAP4 (Panda) and Tegra (Harmony). Patch series against next-20110930.

The two first patches can also be found in Thomas' tree:

	git://tesla.tglx.de/git/linux-2.6-tip irq/core

Changelog:

Marc Zyngier

author

2011-10-03 17:04 UTC #1 lore raw

PATCH v4 1/4 genirq: Add support for per-cpu dev_id interrupts

The ARM GIC interrupt controller offers per CPU interrupts (PPIs), which are usually used to connect local timers to each core. Each CPU has its own private interface to the GIC, and only sees the PPIs that are directly connect to it.

While these timers are separate devices and have a separate interrupt line to a core, they all use the same IRQ number.

For these devices, request_irq() is not the right API as it assumes that an IRQ number is visible by a number of CPUs (through the affinity setting), but makes it very awkward to express that an IRQ number can be handled by all CPUs, and yet be a different interrupt line on each CPU, requiring a different dev_id cookie to be passed back to the handler.

The *_percpu_irq() functions is designed to overcome these limitations, by providing a per-cpu dev_id vector:

int request_percpu_irq(unsigned int irq, irq_handler_t handler,

		   const char *devname, void __percpu *percpu_dev_id);

void free_percpu_irq(unsigned int, void __percpu *); int setup_percpu_irq(unsigned int irq, struct irqaction *new); void remove_percpu_irq(unsigned int irq, struct irqaction *act); void enable_percpu_irq(unsigned int irq);
void disable_percpu_irq(unsigned int irq);

The API has a number of limitations:
- no interrupt sharing
- no threading
- common handler across all the CPUs

Once the interrupt is requested using setup_percpu_irq() or request_percpu_irq(), it must be enabled by each core that wishes its local interrupt to be delivered.

Based on an initial patch by Thomas Gleixner.

Signed-off-by Marc Zyngier <[email protected]>

Cc linux-arm-kernel at lists.infradead.org

Link http://lkml.kernel.org/r/1316793788-14500-2-git-send-email-marc.zyngier at arm.com

Signed-off-by Thomas Gleixner <[email protected]>

---
 include/linux/interrupt.h |   38 ++++++---
 include/linux/irq.h       |   16 ++++-
 include/linux/irqdesc.h   |    1 +
 kernel/irq/chip.c         |   64 +++++++++++++--
 kernel/irq/internals.h    |   19 +++-
 kernel/irq/irqdesc.c      |   32 +++++++-
 kernel/irq/manage.c       |  202 +++++++++++++++++++++++++++++++++++++++++++--
 kernel/irq/settings.h     |    7 ++
 8 files changed, 345 insertions(+), 34 deletions(-)

include/linux/interrupt.h +27 ~~-11~~

index a103732..1cdfd09 100644
@@ -95,6 +95,7 @@ typedef irqreturn_t (*irq_handler_t)(int, void *);
  * @flags:	flags (see IRQF_* above)
  * @name:	name of the device
  * @dev_id:	cookie to identify the device
+ * @percpu_dev_id:	cookie to identify the device
  * @next:	pointer to the next irqaction for shared interrupts
  * @irq:	interrupt number
  * @dir:	pointer to the proc/irq/NN/name entry

@@ -104,17 +105,18 @@ typedef irqreturn_t (*irq_handler_t)(int, void *);
  * @thread_mask:	bitmask for keeping track of @thread activity
  */
 struct irqaction {
-	irq_handler_t handler;
-	unsigned long flags;
-	void *dev_id;
-	struct irqaction *next;
-	int irq;
-	irq_handler_t thread_fn;
-	struct task_struct *thread;
-	unsigned long thread_flags;
-	unsigned long thread_mask;
-	const char *name;
-	struct proc_dir_entry *dir;
+	irq_handler_t		handler;
+	unsigned long		flags;
+	void			*dev_id;
+	void __percpu		*percpu_dev_id;
+	struct irqaction	*next;
+	int			irq;
+	irq_handler_t		thread_fn;
+	struct task_struct	*thread;
+	unsigned long		thread_flags;
+	unsigned long		thread_mask;
+	const char		*name;
+	struct proc_dir_entry	*dir;
 } ____cacheline_internodealigned_in_smp;
 
 extern irqreturn_t no_action(int cpl, void *dev_id);

@@ -136,6 +138,10 @@ extern int __must_check
 request_any_context_irq(unsigned int irq, irq_handler_t handler,
 			unsigned long flags, const char *name, void *dev_id);
 
+extern int __must_check
+request_percpu_irq(unsigned int irq, irq_handler_t handler,
+		   const char *devname, void __percpu *percpu_dev_id);
+
 extern void exit_irq_thread(void);
 #else

@@ -164,10 +170,18 @@ request_any_context_irq(unsigned int irq, irq_handler_t handler,
 	return request_irq(irq, handler, flags, name, dev_id);
 }
 
+static inline int __must_check
+request_percpu_irq(unsigned int irq, irq_handler_t handler,
+		   const char *devname, void __percpu *percpu_dev_id)
+{
+	return request_irq(irq, handler, 0, devname, percpu_dev_id);
+}
+
 static inline void exit_irq_thread(void) { }
 #endif
 
 extern void free_irq(unsigned int, void *);
+extern void free_percpu_irq(unsigned int, void __percpu *);
 
 struct device;

@@ -207,7 +221,9 @@ extern void devm_free_irq(struct device *dev, unsigned int irq, void *dev_id);
 
 extern void disable_irq_nosync(unsigned int irq);
 extern void disable_irq(unsigned int irq);
+extern void disable_percpu_irq(unsigned int irq);
 extern void enable_irq(unsigned int irq);
+extern void enable_percpu_irq(unsigned int irq);
 
 /* The following three functions are for the core kernel use only. */
 #ifdef CONFIG_GENERIC_HARDIRQS

include/linux/irq.h +15 -1

index f776f94..bff29c5 100644
@@ -66,6 +66,7 @@ typedef	void (*irq_preflow_handler_t)(struct irq_data *data);
  * IRQ_NO_BALANCING		- Interrupt cannot be balanced (affinity set)
  * IRQ_MOVE_PCNTXT		- Interrupt can be migrated from process context
  * IRQ_NESTED_TRHEAD		- Interrupt nests into another thread
+ * IRQ_PER_CPU_DEVID		- Dev_id is a per-cpu variable
  */
 enum {
 	IRQ_TYPE_NONE		= 0x00000000,

@@ -88,12 +89,13 @@ enum {
 	IRQ_MOVE_PCNTXT		= (1 << 14),
 	IRQ_NESTED_THREAD	= (1 << 15),
 	IRQ_NOTHREAD		= (1 << 16),
+	IRQ_PER_CPU_DEVID	= (1 << 17),
 };
 
 #define IRQF_MODIFY_MASK	\
 	(IRQ_TYPE_SENSE_MASK | IRQ_NOPROBE | IRQ_NOREQUEST | \
 	 IRQ_NOAUTOEN | IRQ_MOVE_PCNTXT | IRQ_LEVEL | IRQ_NO_BALANCING | \
-	 IRQ_PER_CPU | IRQ_NESTED_THREAD)
+	 IRQ_PER_CPU | IRQ_NESTED_THREAD | IRQ_NOTHREAD | IRQ_PER_CPU_DEVID)
 
 #define IRQ_NO_BALANCING_MASK	(IRQ_PER_CPU | IRQ_NO_BALANCING)

@@ -367,6 +369,8 @@ enum {
 struct irqaction;
 extern int setup_irq(unsigned int irq, struct irqaction *new);
 extern void remove_irq(unsigned int irq, struct irqaction *act);
+extern int setup_percpu_irq(unsigned int irq, struct irqaction *new);
+extern void remove_percpu_irq(unsigned int irq, struct irqaction *act);
 
 extern void irq_cpu_online(void);
 extern void irq_cpu_offline(void);

@@ -394,6 +398,7 @@ extern void handle_edge_irq(unsigned int irq, struct irq_desc *desc);
 extern void handle_edge_eoi_irq(unsigned int irq, struct irq_desc *desc);
 extern void handle_simple_irq(unsigned int irq, struct irq_desc *desc);
 extern void handle_percpu_irq(unsigned int irq, struct irq_desc *desc);
+extern void handle_percpu_devid_irq(unsigned int irq, struct irq_desc *desc);
 extern void handle_bad_irq(unsigned int irq, struct irq_desc *desc);
 extern void handle_nested_irq(unsigned int irq);

@@ -422,6 +427,8 @@ static inline void irq_set_chip_and_handler(unsigned int irq, struct irq_chip *c
 	irq_set_chip_and_handler_name(irq, chip, handle, NULL);
 }
 
+extern int irq_set_percpu_devid(unsigned int irq);
+
 extern void
 __irq_set_handler(unsigned int irq, irq_flow_handler_t handle, int is_chained,
 		  const char *name);

@@ -483,6 +490,13 @@ static inline void irq_set_nested_thread(unsigned int irq, bool nest)
 		irq_clear_status_flags(irq, IRQ_NESTED_THREAD);
 }
 
+static inline void irq_set_percpu_devid_flags(unsigned int irq)
+{
+	irq_set_status_flags(irq,
+			     IRQ_NOAUTOEN | IRQ_PER_CPU | IRQ_NOTHREAD |
+			     IRQ_NOPROBE | IRQ_PER_CPU_DEVID);
+}
+
 /* Handle dynamic irq creation and destruction */
 extern unsigned int create_irq_nr(unsigned int irq_want, int node);
 extern int create_irq(void);

include/linux/irqdesc.h +1 -0

index d9a9f61..f1e2527 100644
@@ -54,6 +54,7 @@ struct irq_desc {
 	unsigned long		last_unhandled;	/* Aging timer for unhandled count */
 	unsigned int		irqs_unhandled;
 	raw_spinlock_t		lock;
+	struct cpumask		*percpu_enabled;
 #ifdef CONFIG_SMP
 	const struct cpumask	*affinity_hint;
 	struct irq_affinity_notify *affinity_notify;

kernel/irq/chip.c +57 -7

117 lines not on this page · raw message

kernel/irq/internals.h +14 -5

index 6546431..a73dd6c 100644
@@ -71,6 +71,8 @@ extern int irq_startup(struct irq_desc *desc);
 extern void irq_shutdown(struct irq_desc *desc);
 extern void irq_enable(struct irq_desc *desc);
 extern void irq_disable(struct irq_desc *desc);
+extern void irq_percpu_enable(struct irq_desc *desc, unsigned int cpu);
+extern void irq_percpu_disable(struct irq_desc *desc, unsigned int cpu);
 extern void mask_irq(struct irq_desc *desc);
 extern void unmask_irq(struct irq_desc *desc);

@@ -114,14 +116,21 @@ static inline void chip_bus_sync_unlock(struct irq_desc *desc)
 		desc->irq_data.chip->irq_bus_sync_unlock(&desc->irq_data);
 }
 
+#define _IRQ_DESC_CHECK		(1 << 0)
+#define _IRQ_DESC_PERCPU	(1 << 1)
+
+#define IRQ_GET_DESC_CHECK_GLOBAL	(_IRQ_DESC_CHECK)
+#define IRQ_GET_DESC_CHECK_PERCPU	(_IRQ_DESC_CHECK | _IRQ_DESC_PERCPU)
+
 struct irq_desc *
-__irq_get_desc_lock(unsigned int irq, unsigned long *flags, bool bus);
+__irq_get_desc_lock(unsigned int irq, unsigned long *flags, bool bus,
+		    unsigned int check);
 void __irq_put_desc_unlock(struct irq_desc *desc, unsigned long flags, bool bus);
 
 static inline struct irq_desc *
-irq_get_desc_buslock(unsigned int irq, unsigned long *flags)
+irq_get_desc_buslock(unsigned int irq, unsigned long *flags, unsigned int check)
 {
-	return __irq_get_desc_lock(irq, flags, true);
+	return __irq_get_desc_lock(irq, flags, true, check);
 }
 
 static inline void

@@ -131,9 +140,9 @@ irq_put_desc_busunlock(struct irq_desc *desc, unsigned long flags)
 }
 
 static inline struct irq_desc *
-irq_get_desc_lock(unsigned int irq, unsigned long *flags)
+irq_get_desc_lock(unsigned int irq, unsigned long *flags, unsigned int check)
 {
-	return __irq_get_desc_lock(irq, flags, false);
+	return __irq_get_desc_lock(irq, flags, false, check);
 }
 
 static inline void

kernel/irq/irqdesc.c +31 -1

index 9888f7e..d86e254 100644
@@ -424,11 +424,22 @@ unsigned int irq_get_next_irq(unsigned int offset)
 }
 
 struct irq_desc *
-__irq_get_desc_lock(unsigned int irq, unsigned long *flags, bool bus)
+__irq_get_desc_lock(unsigned int irq, unsigned long *flags, bool bus,
+		    unsigned int check)
 {
 	struct irq_desc *desc = irq_to_desc(irq);
 
 	if (desc) {
+		if (check & _IRQ_DESC_CHECK) {
+			if ((check & _IRQ_DESC_PERCPU) &&
+			    !irq_settings_is_per_cpu_devid(desc))
+				return NULL;
+
+			if (!(check & _IRQ_DESC_PERCPU) &&
+			    irq_settings_is_per_cpu_devid(desc))
+				return NULL;
+		}
+
 		if (bus)
 			chip_bus_lock(desc);
 		raw_spin_lock_irqsave(&desc->lock, *flags);

@@ -443,6 +454,25 @@ void __irq_put_desc_unlock(struct irq_desc *desc, unsigned long flags, bool bus)
 		chip_bus_sync_unlock(desc);
 }
 
+int irq_set_percpu_devid(unsigned int irq)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+
+	if (!desc)
+		return -EINVAL;
+
+	if (desc->percpu_enabled)
+		return -EINVAL;
+
+	desc->percpu_enabled = kzalloc(sizeof(*desc->percpu_enabled), GFP_KERNEL);
+
+	if (!desc->percpu_enabled)
+		return -ENOMEM;
+
+	irq_set_percpu_devid_flags(irq);
+	return 0;
+}
+
 /**
  * dynamic_irq_cleanup - cleanup a dynamically allocated irq
  * @irq:	irq number to initialize

kernel/irq/manage.c +193 -9

265 lines not on this page · raw message

kernel/irq/settings.h +7 -0

index f166783..1162f10 100644
@@ -13,6 +13,7 @@ enum {
 	_IRQ_MOVE_PCNTXT	= IRQ_MOVE_PCNTXT,
 	_IRQ_NO_BALANCING	= IRQ_NO_BALANCING,
 	_IRQ_NESTED_THREAD	= IRQ_NESTED_THREAD,
+	_IRQ_PER_CPU_DEVID	= IRQ_PER_CPU_DEVID,
 	_IRQF_MODIFY_MASK	= IRQF_MODIFY_MASK,
 };

@@ -24,6 +25,7 @@ enum {
 #define IRQ_NOTHREAD		GOT_YOU_MORON
 #define IRQ_NOAUTOEN		GOT_YOU_MORON
 #define IRQ_NESTED_THREAD	GOT_YOU_MORON
+#define IRQ_PER_CPU_DEVID	GOT_YOU_MORON
 #undef IRQF_MODIFY_MASK
 #define IRQF_MODIFY_MASK	GOT_YOU_MORON

@@ -39,6 +41,11 @@ static inline bool irq_settings_is_per_cpu(struct irq_desc *desc)
 	return desc->status_use_accessors & _IRQ_PER_CPU;
 }
 
+static inline bool irq_settings_is_per_cpu_devid(struct irq_desc *desc)
+{
+	return desc->status_use_accessors & _IRQ_PER_CPU_DEVID;
+}
+
 static inline void irq_settings_set_per_cpu(struct irq_desc *desc)
 {
 	desc->status_use_accessors |= _IRQ_PER_CPU;

Signature · 1 line

1.7.0.4

Marc Zyngier

author

2011-10-03 17:04 UTC #2 lore raw

PATCH v4 2/4 genirq: percpu: allow interrupt type to be set at enable time

In reply to Marc Zyngier

As request_percpu_irq() doesn't allow for a percpu interrupt to have its type configured (it is generally impossible to configure it on all CPUs at once), add a 'type' argument to enable_percpu_irq().

This allows some low-level, board specific init code to be switched to a generic API.

[ tglx: Added WARN_ON argument ]

Signed-off-by Marc Zyngier <[email protected]>

Cc Abhijeet Dharmapurikar <[email protected]>

Signed-off-by Thomas Gleixner <[email protected]>

---
 include/linux/interrupt.h |    2 +-
 kernel/irq/manage.c       |   15 ++++++++++++++-
 2 files changed, 15 insertions(+), 2 deletions(-)

include/linux/interrupt.h +1 -1

index 1cdfd09..664544f 100644
@@ -223,7 +223,7 @@ extern void disable_irq_nosync(unsigned int irq);
 extern void disable_irq(unsigned int irq);
 extern void disable_percpu_irq(unsigned int irq);
 extern void enable_irq(unsigned int irq);
-extern void enable_percpu_irq(unsigned int irq);
+extern void enable_percpu_irq(unsigned int irq, unsigned int type);
 
 /* The following three functions are for the core kernel use only. */
 #ifdef CONFIG_GENERIC_HARDIRQS

kernel/irq/manage.c +14 -1

index 7b4b156..2bc8686 100644
@@ -1419,7 +1419,7 @@ int request_any_context_irq(unsigned int irq, irq_handler_t handler,
 }
 EXPORT_SYMBOL_GPL(request_any_context_irq);
 
-void enable_percpu_irq(unsigned int irq)
+void enable_percpu_irq(unsigned int irq, unsigned int type)
 {
 	unsigned int cpu = smp_processor_id();
 	unsigned long flags;

@@ -1428,7 +1428,20 @@ void enable_percpu_irq(unsigned int irq)
 	if (!desc)
 		return;
 
+	type &= IRQ_TYPE_SENSE_MASK;
+	if (type != IRQ_TYPE_NONE) {
+		int ret;
+
+		ret = __irq_set_trigger(desc, irq, type);
+
+		if (ret) {
+			WARN(1, "failed to set type for IRQ%d\n, irq");
+			goto out;
+		}
+	}
+
 	irq_percpu_enable(desc, cpu);
+out:
 	irq_put_desc_unlock(desc, flags);
 }

Signature · 1 line

1.7.0.4

Marc Zyngier

author

2011-10-03 17:04 UTC #3 lore raw

PATCH v4 3/4 ARM: gic: consolidate PPI handling

In reply to Marc Zyngier

PPI handling is a bit of an odd beast. It uses its own low level handling code and is hardwired to the local timers (hence lacking a registration interface).

Instead, switch the low handling to the normal SPI handling code. PPIs are handled by the handle_percpu_devid_irq flow.

This also allows the removal of some duplicated code.

Cc Kukjin Kim <[email protected]>

Cc David Brown <[email protected]>

Cc Bryan Huntsman <[email protected]>

Cc Tony Lindgren <[email protected]>

Cc Paul Mundt <[email protected]>

Cc Magnus Damm <[email protected]>

Cc Thomas Gleixner <[email protected]>

Acked-by David Brown <[email protected]>

Tested-by David Brown <[email protected]>

Tested-by Shawn Guo <[email protected]>

Signed-off-by Marc Zyngier <[email protected]>

---
 arch/arm/common/Kconfig                           |    1 +
 arch/arm/common/gic.c                             |   70 +++++++++++++++++++-
 arch/arm/include/asm/entry-macro-multi.S          |    7 --
 arch/arm/include/asm/hardirq.h                    |    3 -
 arch/arm/include/asm/hardware/entry-macro-gic.S   |   19 +-----
 arch/arm/include/asm/localtimer.h                 |    6 +-
 arch/arm/include/asm/smp.h                        |    5 --
 arch/arm/kernel/irq.c                             |    3 -
 arch/arm/kernel/smp.c                             |   27 ++------
 arch/arm/mach-exynos4/include/mach/entry-macro.S  |    6 +--
 arch/arm/mach-msm/board-msm8x60.c                 |   11 ---
 arch/arm/mach-msm/include/mach/entry-macro-qgic.S |   73 +--------------------
 arch/arm/mach-omap2/include/mach/entry-macro.S    |   14 +----
 arch/arm/mach-shmobile/entry-intc.S               |    3 -
 arch/arm/mach-shmobile/include/mach/entry-macro.S |    3 -
 15 files changed, 84 insertions(+), 167 deletions(-)

arch/arm/common/Kconfig +1 -0

index 4b71766..114a432 100644
@@ -1,4 +1,5 @@
 config ARM_GIC
+	select IRQ_PERCPU_DEVID
 	bool
 
 config ARM_VIC

arch/arm/common/gic.c +69 -1

104 lines not on this page · raw message

arch/arm/include/asm/entry-macro-multi.S +0 -7

index 2f1e209..88d6181 100644
@@ -25,13 +25,6 @@
 	movne	r1, sp
 	adrne	lr, BSYM(1b)
 	bne	do_IPI
-
-#ifdef CONFIG_LOCAL_TIMERS
-	test_for_ltirq r0, r2, r6, lr
-	movne	r0, sp
-	adrne	lr, BSYM(1b)
-	bne	do_local_timer
-#endif
 #endif
 9997:
 	.endm

arch/arm/include/asm/hardirq.h +0 -3

index 89ad180..ddf07a9 100644
@@ -9,9 +9,6 @@
 
 typedef struct {
 	unsigned int __softirq_pending;
-#ifdef CONFIG_LOCAL_TIMERS
-	unsigned int local_timer_irqs;
-#endif
 #ifdef CONFIG_SMP
 	unsigned int ipi_irqs[NR_IPI];
 #endif

arch/arm/include/asm/hardware/entry-macro-gic.S +2 ~~-17~~

index c115b82..74ebc80 100644
@@ -22,15 +22,11 @@
  * interrupt controller spec.  To wit:
  *
  * Interrupts 0-15 are IPI
- * 16-28 are reserved
- * 29-31 are local.  We allow 30 to be used for the watchdog.
+ * 16-31 are local.  We allow 30 to be used for the watchdog.
  * 32-1020 are global
  * 1021-1022 are reserved
  * 1023 is "spurious" (no interrupt)
  *
- * For now, we ignore all local interrupts so only return an interrupt if it's
- * between 30 and 1020.  The test_for_ipi routine below will pick up on IPIs.
- *
  * A simple read from the controller will tell us the number of the highest
  * priority enabled interrupt.  We then just need to check whether it is in the
  * valid range for an IRQ (30-1020 inclusive).

@@ -43,7 +39,7 @@
 
 	ldr	\tmp, =1021
 	bic     \irqnr, \irqstat, #0x1c00
-	cmp     \irqnr, #29
+	cmp     \irqnr, #15
 	cmpcc	\irqnr, \irqnr
 	cmpne	\irqnr, \tmp
 	cmpcs	\irqnr, \irqnr

@@ -62,14 +58,3 @@
 	strcc	\irqstat, [\base, #GIC_CPU_EOI]
 	cmpcs	\irqnr, \irqnr
 	.endm
-
-/* As above, this assumes that irqstat and base are preserved.. */
-
-	.macro test_for_ltirq, irqnr, irqstat, base, tmp
-	bic	\irqnr, \irqstat, #0x1c00
-	mov 	\tmp, #0
-	cmp	\irqnr, #29
-	moveq	\tmp, #1
-	streq	\irqstat, [\base, #GIC_CPU_EOI]
-	cmp	\tmp, #0
-	.endm

arch/arm/include/asm/localtimer.h +4 -2

index 080d74f..e3663f7 100644
@@ -10,6 +10,8 @@
 #ifndef __ASM_ARM_LOCALTIMER_H
 #define __ASM_ARM_LOCALTIMER_H
 
+#include <linux/interrupt.h>
+
 struct clock_event_device;
 
 /*

@@ -18,9 +20,9 @@ struct clock_event_device;
 void percpu_timer_setup(void);
 
 /*
- * Called from assembly, this is the local timer IRQ handler
+ * Per-cpu timer IRQ handler
  */
-asmlinkage void do_local_timer(struct pt_regs *);
+irqreturn_t percpu_timer_handler(int irq, void *dev_id);
 
 
 #ifdef CONFIG_LOCAL_TIMERS

arch/arm/include/asm/smp.h +0 -5

index bf25484..83f9b57 100644
@@ -79,9 +79,4 @@ extern void cpu_die(void);
 extern void arch_send_call_function_single_ipi(int cpu);
 extern void arch_send_call_function_ipi_mask(const struct cpumask *mask);
 
-/*
- * show local interrupt info
- */
-extern void show_local_irqs(struct seq_file *, int);
-
 #endif /* ifndef __ASM_ARM_SMP_H */

arch/arm/kernel/irq.c +0 -3

index e20a5d0..8e744f6 100644
@@ -58,9 +58,6 @@ int arch_show_interrupts(struct seq_file *p, int prec)
 #ifdef CONFIG_SMP
 	show_ipi_list(p, prec);
 #endif
-#ifdef CONFIG_LOCAL_TIMERS
-	show_local_irqs(p, prec);
-#endif
 	seq_printf(p, "%*s: %10lu\n", prec, "Err", irq_err_count);
 	return 0;
 }

arch/arm/kernel/smp.c +5 ~~-22~~

index c594ed2..979404a 100644
@@ -504,10 +504,6 @@ u64 smp_irq_stat_cpu(unsigned int cpu)
 	for (i = 0; i < NR_IPI; i++)
 		sum += __get_irq_stat(cpu, ipi_irqs[i]);
 
-#ifdef CONFIG_LOCAL_TIMERS
-	sum += __get_irq_stat(cpu, local_timer_irqs);
-#endif
-
 	return sum;
 }

@@ -525,29 +521,16 @@ static void ipi_timer(void)
 }
 
 #ifdef CONFIG_LOCAL_TIMERS
-asmlinkage void __exception_irq_entry do_local_timer(struct pt_regs *regs)
+irqreturn_t percpu_timer_handler(int irq, void *dev_id)
 {
-	struct pt_regs *old_regs = set_irq_regs(regs);
-	int cpu = smp_processor_id();
+	struct clock_event_device *evt = &__get_cpu_var(percpu_clockevent);
 
 	if (local_timer_ack()) {
-		__inc_irq_stat(cpu, local_timer_irqs);
-		ipi_timer();
+		evt->event_handler(evt);
+		return IRQ_HANDLED;
 	}
 
-	set_irq_regs(old_regs);
-}
-
-void show_local_irqs(struct seq_file *p, int prec)
-{
-	unsigned int cpu;
-
-	seq_printf(p, "%*s: ", prec, "LOC");
-
-	for_each_present_cpu(cpu)
-		seq_printf(p, "%10u ", __get_irq_stat(cpu, local_timer_irqs));
-
-	seq_printf(p, " Local timer interrupts\n");
+	return IRQ_NONE;
 }
 #endif

arch/arm/mach-exynos4/include/mach/entry-macro.S +1 -5

index d7a1e28..807d05d 100644
@@ -55,7 +55,7 @@
 
 		bic     \irqnr, \irqstat, #0x1c00
 
-		cmp     \irqnr, #29
+		cmp     \irqnr, #15
 		cmpcc	\irqnr, \irqnr
 		cmpne	\irqnr, \tmp
 		cmpcs	\irqnr, \irqnr

@@ -77,7 +77,3 @@
 		cmpcs	\irqnr, \irqnr
 		.endm
 
-		/* As above, this assumes that irqstat and base are preserved.. */
-
-		.macro test_for_ltirq, irqnr, irqstat, base, tmp
-		.endm

arch/arm/mach-msm/board-msm8x60.c +0 ~~-11~~

index a4bd858..30c6b58 100644
@@ -53,8 +53,6 @@ static void __init msm8x60_map_io(void)
 
 static void __init msm8x60_init_irq(void)
 {
-	unsigned int i;
-
 	gic_init(0, GIC_PPI_START, MSM_QGIC_DIST_BASE,
 		 (void *)MSM_QGIC_CPU_BASE);

@@ -66,15 +64,6 @@ static void __init msm8x60_init_irq(void)
 	 */
 	if (!machine_is_msm8x60_sim())
 		writel(0x0000FFFF, MSM_QGIC_DIST_BASE + GIC_DIST_ENABLE_SET);
-
-	/* FIXME: Not installing AVS_SVICINT and AVS_SVICINTSWDONE yet
-	 * as they are configured as level, which does not play nice with
-	 * handle_percpu_irq.
-	 */
-	for (i = GIC_PPI_START; i < GIC_SPI_START; i++) {
-		if (i != AVS_SVICINT && i != AVS_SVICINTSWDONE)
-			irq_set_handler(i, handle_percpu_irq);
-	}
 }
 
 static void __init msm8x60_init(void)

arch/arm/mach-msm/include/mach/entry-macro-qgic.S +1 ~~-72~~

82 lines not on this page · raw message

arch/arm/mach-omap2/include/mach/entry-macro.S +1 ~~-13~~

index ceb8b7e..feb90a1 100644
@@ -78,7 +78,7 @@
 4401:		ldr     \irqstat, [\base, #GIC_CPU_INTACK]
 		ldr     \tmp, =1021
 		bic     \irqnr, \irqstat, #0x1c00
-		cmp     \irqnr, #29
+		cmp     \irqnr, #15
 		cmpcc   \irqnr, \irqnr
 		cmpne   \irqnr, \tmp
 		cmpcs   \irqnr, \irqnr

@@ -101,18 +101,6 @@
 		it	cs
 		cmpcs	\irqnr, \irqnr
 		.endm
-
-		/* As above, this assumes that irqstat and base are preserved */
-
-		.macro test_for_ltirq, irqnr, irqstat, base, tmp
-		bic	\irqnr, \irqstat, #0x1c00
-		mov 	\tmp, #0
-		cmp	\irqnr, #29
-		itt	eq
-		moveq	\tmp, #1
-		streq	\irqstat, [\base, #GIC_CPU_EOI]
-		cmp	\tmp, #0
-		.endm
 #endif	/* CONFIG_SMP */
 
 #else	/* MULTI_OMAP2 */

arch/arm/mach-shmobile/entry-intc.S +0 -3

index cac0a7a..1a1c00c 100644
@@ -51,7 +51,4 @@
 	.macro  test_for_ipi, irqnr, irqstat, base, tmp
 	.endm
 
-	.macro  test_for_ltirq, irqnr, irqstat, base, tmp
-	.endm
-
 	arch_irq_handler shmobile_handle_irq_intc

arch/arm/mach-shmobile/include/mach/entry-macro.S +0 -3

index d791f10..8d4a416 100644
@@ -27,8 +27,5 @@
 	.macro  test_for_ipi, irqnr, irqstat, base, tmp
 	.endm
 
-	.macro  test_for_ltirq, irqnr, irqstat, base, tmp
-	.endm
-
 	.macro  arch_ret_to_user, tmp1, tmp2
 	.endm

Signature · 1 line

1.7.0.4

Marc Zyngier

author

2011-10-03 17:04 UTC #4 lore raw

PATCH v4 4/4 ARM: gic, local timers: use the request_percpu_irq() interface

In reply to Marc Zyngier

This patch remove the hardcoded link between local timers and PPIs, and convert the PPI users (TWD and MSM timers) to the new *_percpu_irq interface. Also some collateral cleanup (local_timer_ack() is gone, and the interrupt handler is strictly private to each driver).

PPIs are now useable for more than just the local timers.

Additional testing by David Brown (msm8250 and msm8660) and Shawn Guo (imx6q).

Cc David Brown <[email protected]>

Cc Thomas Gleixner <[email protected]>

Acked-by David Brown <[email protected]>

Tested-by David Brown <[email protected]>

Tested-by Shawn Guo <[email protected]>

Signed-off-by Marc Zyngier <[email protected]>

---
 arch/arm/common/gic.c               |   52 --------------------------
 arch/arm/include/asm/hardware/gic.h |    1 -
 arch/arm/include/asm/localtimer.h   |   17 ++++-----
 arch/arm/include/asm/smp_twd.h      |    2 +-
 arch/arm/kernel/smp.c               |   16 +--------
 arch/arm/kernel/smp_twd.c           |   47 +++++++++++++++++++++++-
 arch/arm/mach-exynos4/mct.c         |    5 ---
 arch/arm/mach-msm/timer.c           |   69 ++++++++++++++++++++---------------
 8 files changed, 94 insertions(+), 115 deletions(-)

arch/arm/common/gic.c +0 ~~-52~~

index 9b83077..a3f335c 100644
@@ -35,7 +35,6 @@
 #include <asm/irq.h>
 #include <asm/mach/irq.h>
 #include <asm/hardware/gic.h>
-#include <asm/localtimer.h>
 
 static DEFINE_RAW_SPINLOCK(irq_controller_lock);

@@ -259,32 +258,6 @@ void __init gic_cascade_irq(unsigned int gic_nr, unsigned int irq)
 	irq_set_chained_handler(irq, gic_handle_cascade_irq);
 }
 
-#ifdef CONFIG_LOCAL_TIMERS
-#define gic_ppi_handler		percpu_timer_handler
-#else
-static irqreturn_t gic_ppi_handler(int irq, void *dev_id)
-{
-	return IRQ_NONE;
-}
-#endif
-
-#define PPI_IRQACT(nr)						\
-	{							\
-		.handler	= gic_ppi_handler,		\
-		.flags		= IRQF_PERCPU | IRQF_TIMER,	\
-		.irq		= nr,				\
-		.name		= "PPI-" # nr,			\
-	}
-
-static struct irqaction ppi_irqaction_template[16] __initdata = {
-	PPI_IRQACT(0),  PPI_IRQACT(1),  PPI_IRQACT(2),  PPI_IRQACT(3),
-	PPI_IRQACT(4),  PPI_IRQACT(5),  PPI_IRQACT(6),  PPI_IRQACT(7),
-	PPI_IRQACT(8),  PPI_IRQACT(9),  PPI_IRQACT(10), PPI_IRQACT(11),
-	PPI_IRQACT(12), PPI_IRQACT(13), PPI_IRQACT(14), PPI_IRQACT(15),
-};
-
-static struct irqaction *ppi_irqaction;
-
 static void __init gic_dist_init(struct gic_chip_data *gic,
 	unsigned int irq_start)
 {

@@ -320,16 +293,6 @@ static void __init gic_dist_init(struct gic_chip_data *gic,
 	if (gic == &gic_data[0]) {
 		nrppis = 16 - (irq_start & 15);
 		ppi_base = gic->irq_offset + 32 - nrppis;
-
-		ppi_irqaction = kmemdup(&ppi_irqaction_template[16 - nrppis],
-					sizeof(*ppi_irqaction) * nrppis,
-					GFP_KERNEL);
-
-		if (nrppis && !ppi_irqaction) {
-			pr_err("GIC: Can't allocate PPI memory");
-			nrppis = 0;
-			ppi_base = 0;
-		}
 	}
 
 	pr_info("Configuring GIC with %d sources (%d PPIs)\n",

@@ -372,17 +335,12 @@ static void __init gic_dist_init(struct gic_chip_data *gic,
 	 */
 	for (i = 0; i < nrppis; i++) {
 		int ppi = i + ppi_base;
-		int err;
 
 		irq_set_percpu_devid(ppi);
 		irq_set_chip_and_handler(ppi, &gic_chip,
 					 handle_percpu_devid_irq);
 		irq_set_chip_data(ppi, gic);
 		set_irq_flags(ppi, IRQF_VALID | IRQF_NOAUTOEN);
-
-		err = setup_percpu_irq(ppi, &ppi_irqaction[i]);
-		if (err)
-			pr_err("GIC: can't setup PPI%d (%d)\n", ppi, err);
 	}
 
 	for (i = irq_start + nrppis; i < irq_limit; i++) {

@@ -443,16 +401,6 @@ void __cpuinit gic_secondary_init(unsigned int gic_nr)
 	gic_cpu_init(&gic_data[gic_nr]);
 }
 
-void __cpuinit gic_enable_ppi(unsigned int irq)
-{
-	unsigned long flags;
-
-	local_irq_save(flags);
-	irq_set_status_flags(irq, IRQ_NOPROBE);
-	gic_unmask_irq(irq_get_irq_data(irq));
-	local_irq_restore(flags);
-}
-
 #ifdef CONFIG_SMP
 void gic_raise_softirq(const struct cpumask *mask, unsigned int irq)
 {

arch/arm/include/asm/hardware/gic.h +0 -1

index 435d3f8..2dadd50 100644
@@ -40,7 +40,6 @@ void gic_init(unsigned int, unsigned int, void __iomem *, void __iomem *);
 void gic_secondary_init(unsigned int);
 void gic_cascade_irq(unsigned int gic_nr, unsigned int irq);
 void gic_raise_softirq(const struct cpumask *mask, unsigned int irq);
-void gic_enable_ppi(unsigned int);
 
 struct gic_chip_data {
 	unsigned int irq_offset;

arch/arm/include/asm/localtimer.h +7 ~~-10~~

index e3663f7..f5e1cec 100644
@@ -19,27 +19,20 @@ struct clock_event_device;
  */
 void percpu_timer_setup(void);
 
-/*
- * Per-cpu timer IRQ handler
- */
-irqreturn_t percpu_timer_handler(int irq, void *dev_id);
-
-
 #ifdef CONFIG_LOCAL_TIMERS
 
 #ifdef CONFIG_HAVE_ARM_TWD
 
 #include "smp_twd.h"
 
-#define local_timer_ack()	twd_timer_ack()
+#define local_timer_stop(c)	twd_timer_stop((c))
 
 #else
 
 /*
- * Platform provides this to acknowledge a local timer IRQ.
- * Returns true if the local timer IRQ is to be processed.
+ * Stop the local timer
  */
-int local_timer_ack(void);
+void local_timer_stop(struct clock_event_device *);
 
 #endif

@@ -54,6 +47,10 @@ static inline int local_timer_setup(struct clock_event_device *evt)
 {
 	return -ENXIO;
 }
+
+static inline void local_timer_stop(struct clock_event_device *evt)
+{
+}
 #endif
 
 #endif

arch/arm/include/asm/smp_twd.h +1 -1

index fed9981..ef9ffba 100644
@@ -22,7 +22,7 @@ struct clock_event_device;
 
 extern void __iomem *twd_base;
 
-int twd_timer_ack(void);
 void twd_timer_setup(struct clock_event_device *);
+void twd_timer_stop(struct clock_event_device *);
 
 #endif

arch/arm/kernel/smp.c +1 ~~-15~~

index 979404a..df5bc0a 100644
@@ -520,20 +520,6 @@ static void ipi_timer(void)
 	irq_exit();
 }
 
-#ifdef CONFIG_LOCAL_TIMERS
-irqreturn_t percpu_timer_handler(int irq, void *dev_id)
-{
-	struct clock_event_device *evt = &__get_cpu_var(percpu_clockevent);
-
-	if (local_timer_ack()) {
-		evt->event_handler(evt);
-		return IRQ_HANDLED;
-	}
-
-	return IRQ_NONE;
-}
-#endif
-
 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 static void smp_timer_broadcast(const struct cpumask *mask)
 {

@@ -584,7 +570,7 @@ static void percpu_timer_stop(void)
 	unsigned int cpu = smp_processor_id();
 	struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu);
 
-	evt->set_mode(CLOCK_EVT_MODE_UNUSED, evt);
+	local_timer_stop(evt);
 }
 #endif

arch/arm/kernel/smp_twd.c +45 -2

82 lines not on this page · raw message

arch/arm/mach-exynos4/mct.c +0 -5

index ddd8686..b3a0016 100644
@@ -402,11 +402,6 @@ int __cpuinit local_timer_setup(struct clock_event_device *evt)
 	return 0;
 }
 
-int local_timer_ack(void)
-{
-	return 0;
-}
-
 #endif /* CONFIG_LOCAL_TIMERS */
 
 static void __init exynos4_timer_resources(void)

arch/arm/mach-msm/timer.c +40 ~~-29~~

136 lines not on this page · raw message

Signature · 1 line

1.7.0.4

Russell King - ARM Linux

2011-10-13 18:14 UTC #5 lore raw

v4 cover genirq: handling GIC per-cpu interrupts

In reply to Marc Zyngier

Quoted 19 lines · Marc Zyngier

The current GIC per-cpu interrupts (aka PPIs) suffer from a number of problems:
- They use a completely separate scheme to handle the interrupts, mostly because the PPI concept doesn't really match the kernel view of an interrupt.
- PPIs can only be used by the timer code, unless we add more low-level assembly code.
- The local timer code can only be used by devices generating PPIs, and not SPIs.
- At least one platform (msm) has started implementing its own alternative scheme.
- Some low-level code gets duplicated, as usual...
The proposed solution is to handle the PPIs using the same path as SPIs. A new core API is added to deal with per-cpu interrupts in a less awkward way. The local timer code is updated to reflect these changes.

Quoted 8 lines

The core API changes are based on an initial idea by Thomas Gleixner.
Tested on ARM Versatile Express (Cortex A15), ARM RealView PB11MP, OMAP4 (Panda) and Tegra (Harmony). Patch series against next-20110930.
The two first patches can also be found in Thomas' tree:
	git://tesla.tglx.de/git/linux-2.6-tip irq/core

So, how do we deal with merging this without ending up with some problematical inter-tree dependencies?

It looks like I'll see conflicts with:
arch/arm/common/gic.c
arch/arm/kernel/smp.c
arch/arm/include/asm/localtimer.h

and possibly:
arch/arm/include/asm/smp.h
arch/arm/kernel/irq.c

as well. I've not checked with patch 4, so there may be some more too.

Some of this is probably because of 7123/1 and 7124/1.

Marc Zyngier

author

2011-10-14 12:41 UTC #6 lore raw

v4 cover genirq: handling GIC per-cpu interrupts

Quoted 25 lines · Russell King - ARM Linux

Quoted 24 lines · Marc Zyngier
The current GIC per-cpu interrupts (aka PPIs) suffer from a number of problems:
- They use a completely separate scheme to handle the interrupts, mostly because the PPI concept doesn't really match the kernel view of an interrupt.
- PPIs can only be used by the timer code, unless we add more low-level assembly code.
- The local timer code can only be used by devices generating PPIs, and not SPIs.
- At least one platform (msm) has started implementing its own alternative scheme.
- Some low-level code gets duplicated, as usual...
The proposed solution is to handle the PPIs using the same path as SPIs. A new core API is added to deal with per-cpu interrupts in a less awkward way. The local timer code is updated to reflect these changes.
The core API changes are based on an initial idea by Thomas Gleixner.
Tested on ARM Versatile Express (Cortex A15), ARM RealView PB11MP, OMAP4 (Panda) and Tegra (Harmony). Patch series against next-20110930.

Quoted 6 lines

Quoted 3 lines
The two first patches can also be found in Thomas' tree:
	git://tesla.tglx.de/git/linux-2.6-tip irq/core
So, how do we deal with merging this without ending up with some problematical inter-tree dependencies?

My view on this is that the whole series should ideally be merged via one tree only. I suspect that yours would be the best candidate, as there is probably little chance of conflicts on the core code.

Otherwise, we'd have to do a two step merge, adding the ARM bits once the core code has been merged.

Quoted 5 lines

It looks like I'll see conflicts with:
arch/arm/common/gic.c
arch/arm/kernel/smp.c
arch/arm/include/asm/localtimer.h

Quoted 7 lines

and possibly:
arch/arm/include/asm/smp.h
arch/arm/kernel/irq.c
as well. I've not checked with patch 4, so there may be some more too.
Some of this is probably because of 7123/1 and 7124/1.

Do you have a branch you consider stable enough for me to rebase this series on? I've already solved these conflicts against -next, so rebasing it should be faily trivial.

Thanks,

M.

Signature · 1 line

Jazz is not dead. It just smells funny...

Marc Zyngier

author

2011-10-18 12:39 UTC #7 lore raw

v4 cover genirq: handling GIC per-cpu interrupts

In reply to Russell King - ARM Linux

Quoted 37 lines · Russell King - ARM Linux

Quoted 19 lines · Marc Zyngier
The current GIC per-cpu interrupts (aka PPIs) suffer from a number of problems:
- They use a completely separate scheme to handle the interrupts, mostly because the PPI concept doesn't really match the kernel view of an interrupt.
- PPIs can only be used by the timer code, unless we add more low-level assembly code.
- The local timer code can only be used by devices generating PPIs, and not SPIs.
- At least one platform (msm) has started implementing its own alternative scheme.
- Some low-level code gets duplicated, as usual...
The proposed solution is to handle the PPIs using the same path as SPIs. A new core API is added to deal with per-cpu interrupts in a less awkward way. The local timer code is updated to reflect these changes.
Quoted 8 lines
The core API changes are based on an initial idea by Thomas Gleixner.
Tested on ARM Versatile Express (Cortex A15), ARM RealView PB11MP, OMAP4 (Panda) and Tegra (Harmony). Patch series against next-20110930.
The two first patches can also be found in Thomas' tree:
	git://tesla.tglx.de/git/linux-2.6-tip irq/core
So, how do we deal with merging this without ending up with some problematical inter-tree dependencies?
It looks like I'll see conflicts with:
arch/arm/common/gic.c
arch/arm/kernel/smp.c
arch/arm/include/asm/localtimer.h

Quoted 7 lines

and possibly:
arch/arm/include/asm/smp.h
arch/arm/kernel/irq.c
as well. I've not checked with patch 4, so there may be some more too.
Some of this is probably because of 7123/1 and 7124/1.

I've set up a branch based on your "smp" branch, resolving the above conflicts:

git://github.com/mzyngier/arm-platforms.git ppi-for-rmk

M.

Signature · 1 line

Jazz is not dead. It just smells funny...

Shawn Guo

2011-10-20 07:37 UTC #8 lore raw

v4 cover genirq: handling GIC per-cpu interrupts

Quoted 42 lines · Marc Zyngier

Quoted 41 lines · Russell King - ARM Linux
Quoted 19 lines · Marc Zyngier
The current GIC per-cpu interrupts (aka PPIs) suffer from a number of problems:
- They use a completely separate scheme to handle the interrupts, mostly because the PPI concept doesn't really match the kernel view of an interrupt.
- PPIs can only be used by the timer code, unless we add more low-level assembly code.
- The local timer code can only be used by devices generating PPIs, and not SPIs.
- At least one platform (msm) has started implementing its own alternative scheme.
- Some low-level code gets duplicated, as usual...
The proposed solution is to handle the PPIs using the same path as SPIs. A new core API is added to deal with per-cpu interrupts in a less awkward way. The local timer code is updated to reflect these changes.
Quoted 8 lines
The core API changes are based on an initial idea by Thomas Gleixner.
Tested on ARM Versatile Express (Cortex A15), ARM RealView PB11MP, OMAP4 (Panda) and Tegra (Harmony). Patch series against next-20110930.
The two first patches can also be found in Thomas' tree:
	git://tesla.tglx.de/git/linux-2.6-tip irq/core
So, how do we deal with merging this without ending up with some problematical inter-tree dependencies?
It looks like I'll see conflicts with:
arch/arm/common/gic.c
arch/arm/kernel/smp.c
arch/arm/include/asm/localtimer.h
and possibly:
arch/arm/include/asm/smp.h
arch/arm/kernel/irq.c

Quoted 9 lines

Quoted 3 lines
as well. I've not checked with patch 4, so there may be some more too.
Some of this is probably because of 7123/1 and 7124/1.
I've set up a branch based on your "smp" branch, resolving the above conflicts:
git://github.com/mzyngier/arm-platforms.git ppi-for-rmk

Hi Russell,

It seems that you are going to queue this series for v3.2-rc1. I'm moving my imx6q series onto it. Otherwise, please let me know.

Signature · 2 lines

Regards,
Shawn

Russell King - ARM Linux

2011-10-20 08:21 UTC #9 lore raw

v4 cover genirq: handling GIC per-cpu interrupts

In reply to Marc Zyngier

Quoted 42 lines · Marc Zyngier

Quoted 41 lines · Russell King - ARM Linux
Quoted 19 lines · Marc Zyngier
The current GIC per-cpu interrupts (aka PPIs) suffer from a number of problems:
- They use a completely separate scheme to handle the interrupts, mostly because the PPI concept doesn't really match the kernel view of an interrupt.
- PPIs can only be used by the timer code, unless we add more low-level assembly code.
- The local timer code can only be used by devices generating PPIs, and not SPIs.
- At least one platform (msm) has started implementing its own alternative scheme.
- Some low-level code gets duplicated, as usual...
The proposed solution is to handle the PPIs using the same path as SPIs. A new core API is added to deal with per-cpu interrupts in a less awkward way. The local timer code is updated to reflect these changes.
Quoted 8 lines
The core API changes are based on an initial idea by Thomas Gleixner.
Tested on ARM Versatile Express (Cortex A15), ARM RealView PB11MP, OMAP4 (Panda) and Tegra (Harmony). Patch series against next-20110930.
The two first patches can also be found in Thomas' tree:
	git://tesla.tglx.de/git/linux-2.6-tip irq/core
So, how do we deal with merging this without ending up with some problematical inter-tree dependencies?
It looks like I'll see conflicts with:
arch/arm/common/gic.c
arch/arm/kernel/smp.c
arch/arm/include/asm/localtimer.h
and possibly:
arch/arm/include/asm/smp.h
arch/arm/kernel/irq.c

Quoted 8 lines

Quoted 3 lines
as well. I've not checked with patch 4, so there may be some more too.
Some of this is probably because of 7123/1 and 7124/1.
I've set up a branch based on your "smp" branch, resolving the above conflicts:
git://github.com/mzyngier/arm-platforms.git ppi-for-rmk

Please send me a proper pull request - and this almost got lost because it doesn't have a PULL tag in the subject line (and would've if Shawn Guo hadn't replied to this).