ARM: 6532/1: Allow machine to specify it's own IRQ handlers at run-time

Normally different ARM platform has different way to decode the IRQ
hardware status and demultiplex to the corresponding IRQ handler.
This is highly optimized by macro irq_handler in entry-armv.S, and
each machine defines their own macro to decode the IRQ number.
However, this prevents multiple machine classes to be built into a
single kernel.

By allowing each machine to specify thier own handler, and making
function pointer 'handle_arch_irq' to point to it at run time, this
can be solved. And introduce CONFIG_MULTI_IRQ_HANDLER to allow both
solutions to work.

Comparing with the highly optimized macro of irq_handler, the new
function must be written with care not to lose too much performance.
And the IPI stuff on SMP is expected to move to the provided arch
IRQ handler as well.

The assembly code to invoke handle_arch_irq is optimized by Russell
King.

Signed-off-by: Eric Miao <eric.miao@canonical.com>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index fd0e21b..4769486 100644 (file)
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1022,6 +1022,11 @@ config CPU_HAS_PMU
        default y
        bool
 
+config MULTI_IRQ_HANDLER
+       bool
+       help
+         Allow each machine to specify it's own IRQ handler at run time.
+
 if !MMU
 source "arch/arm/Kconfig-nommu"
 endif

diff --git a/arch/arm/include/asm/mach/arch.h b/arch/arm/include/asm/mach/arch.h
index d97a964..7d55356 100644 (file)
--- a/arch/arm/include/asm/mach/arch.h
+++ b/arch/arm/include/asm/mach/arch.h
@@ -40,6 +40,9 @@ struct machine_desc {
        void                    (*init_irq)(void);
        struct sys_timer        *timer;         /* system tick timer    */
        void                    (*init_machine)(void);
+#ifdef CONFIG_MULTI_IRQ_HANDLER
+       void                    (*handle_irq)(struct pt_regs *);
+#endif
 };
 
 /*

diff --git a/arch/arm/include/asm/mach/irq.h b/arch/arm/include/asm/mach/irq.h
index ce3eee9..6ecdad9 100644 (file)
--- a/arch/arm/include/asm/mach/irq.h
+++ b/arch/arm/include/asm/mach/irq.h
@@ -22,6 +22,10 @@ extern void (*init_arch_irq)(void);
 extern void init_FIQ(void);
 extern int show_fiq_list(struct seq_file *, void *);
 
+#ifdef CONFIG_MULTI_IRQ_HANDLER
+extern void (*handle_arch_irq)(struct pt_regs *);
+#endif
+
 /*
  * This is for easy migration, but should be changed in the source
  */

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 35f3f20..caa6c39 100644 (file)
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -30,6 +30,14 @@
  * Interrupt handling.  Preserves r7, r8, r9
  */
        .macro  irq_handler
+#ifdef CONFIG_MULTI_IRQ_HANDLER
+       ldr     r5, =handle_arch_irq
+       mov     r0, sp
+       ldr     r5, [r5]
+       adr     lr, BSYM(9997f)
+       teq     r5, #0
+       movne   pc, r5
+#endif
        get_irqnr_preamble r5, lr
 1:     get_irqnr_and_base r0, r6, r5, lr
        movne   r1, sp
@@ -58,9 +66,8 @@
        adrne   lr, BSYM(1b)
        bne     do_local_timer
 #endif
-9997:
 #endif
-
+9997:
        .endm
 
 #ifdef CONFIG_KPROBES
@@ -1245,3 +1252,9 @@ cr_alignment:
        .space  4
 cr_no_alignment:
        .space  4
+
+#ifdef CONFIG_MULTI_IRQ_HANDLER
+       .globl  handle_arch_irq
+handle_arch_irq:
+       .space  4
+#endif

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 8075e59..0826f36 100644 (file)
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -875,6 +875,9 @@ void __init setup_arch(char **cmdline_p)
        init_arch_irq = mdesc->init_irq;
        system_timer = mdesc->timer;
        init_machine = mdesc->init_machine;
+#ifdef CONFIG_MULTI_IRQ_HANDLER
+       handle_arch_irq = mdesc->handle_irq;
+#endif
 
 #ifdef CONFIG_VT
 #if defined(CONFIG_VGA_CONSOLE)