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[ARM] 4108/2: Allow multiple GIC interrupt controllers in a system
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The current implementation only assumes one GIC to be present in the
system. However, there are platforms with more than one cascaded interrupt
controllers (RealView/EB MPCore for example).

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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Catalin Marinas authored and Russell King committed Feb 15, 2007
1 parent ae0a846 commit b3a1bde
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Showing 4 changed files with 101 additions and 19 deletions.
109 changes: 95 additions & 14 deletions arch/arm/common/gic.c
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,9 @@
*
* o There is one CPU Interface per CPU, which sends interrupts sent
* by the Distributor, and interrupts generated locally, to the
* associated CPU.
* associated CPU. The base address of the CPU interface is usually
* aliased so that the same address points to different chips depending
* on the CPU it is accessed from.
*
* Note that IRQs 0-31 are special - they are local to each CPU.
* As such, the enable set/clear, pending set/clear and active bit
Expand All @@ -31,10 +33,38 @@
#include <asm/mach/irq.h>
#include <asm/hardware/gic.h>

static void __iomem *gic_dist_base;
static void __iomem *gic_cpu_base;
static DEFINE_SPINLOCK(irq_controller_lock);

struct gic_chip_data {
unsigned int irq_offset;
void __iomem *dist_base;
void __iomem *cpu_base;
};

#ifndef MAX_GIC_NR
#define MAX_GIC_NR 1
#endif

static struct gic_chip_data gic_data[MAX_GIC_NR];

static inline void __iomem *gic_dist_base(unsigned int irq)
{
struct gic_chip_data *gic_data = get_irq_chip_data(irq);
return gic_data->dist_base;
}

static inline void __iomem *gic_cpu_base(unsigned int irq)
{
struct gic_chip_data *gic_data = get_irq_chip_data(irq);
return gic_data->cpu_base;
}

static inline unsigned int gic_irq(unsigned int irq)
{
struct gic_chip_data *gic_data = get_irq_chip_data(irq);
return irq - gic_data->irq_offset;
}

/*
* Routines to acknowledge, disable and enable interrupts
*
Expand All @@ -55,8 +85,8 @@ static void gic_ack_irq(unsigned int irq)
u32 mask = 1 << (irq % 32);

spin_lock(&irq_controller_lock);
writel(mask, gic_dist_base + GIC_DIST_ENABLE_CLEAR + (irq / 32) * 4);
writel(irq, gic_cpu_base + GIC_CPU_EOI);
writel(mask, gic_dist_base(irq) + GIC_DIST_ENABLE_CLEAR + (gic_irq(irq) / 32) * 4);
writel(gic_irq(irq), gic_cpu_base(irq) + GIC_CPU_EOI);
spin_unlock(&irq_controller_lock);
}

Expand All @@ -65,7 +95,7 @@ static void gic_mask_irq(unsigned int irq)
u32 mask = 1 << (irq % 32);

spin_lock(&irq_controller_lock);
writel(mask, gic_dist_base + GIC_DIST_ENABLE_CLEAR + (irq / 32) * 4);
writel(mask, gic_dist_base(irq) + GIC_DIST_ENABLE_CLEAR + (gic_irq(irq) / 32) * 4);
spin_unlock(&irq_controller_lock);
}

Expand All @@ -74,14 +104,14 @@ static void gic_unmask_irq(unsigned int irq)
u32 mask = 1 << (irq % 32);

spin_lock(&irq_controller_lock);
writel(mask, gic_dist_base + GIC_DIST_ENABLE_SET + (irq / 32) * 4);
writel(mask, gic_dist_base(irq) + GIC_DIST_ENABLE_SET + (gic_irq(irq) / 32) * 4);
spin_unlock(&irq_controller_lock);
}

#ifdef CONFIG_SMP
static void gic_set_cpu(unsigned int irq, cpumask_t mask_val)
{
void __iomem *reg = gic_dist_base + GIC_DIST_TARGET + (irq & ~3);
void __iomem *reg = gic_dist_base(irq) + GIC_DIST_TARGET + (gic_irq(irq) & ~3);
unsigned int shift = (irq % 4) * 8;
unsigned int cpu = first_cpu(mask_val);
u32 val;
Expand All @@ -95,6 +125,37 @@ static void gic_set_cpu(unsigned int irq, cpumask_t mask_val)
}
#endif

static void fastcall gic_handle_cascade_irq(unsigned int irq,
struct irq_desc *desc)
{
struct gic_chip_data *chip_data = get_irq_data(irq);
struct irq_chip *chip = get_irq_chip(irq);
unsigned int cascade_irq;
unsigned long status;

/* primary controller ack'ing */
chip->ack(irq);

spin_lock(&irq_controller_lock);
status = readl(chip_data->cpu_base + GIC_CPU_INTACK);
spin_unlock(&irq_controller_lock);

cascade_irq = (status & 0x3ff);
if (cascade_irq > 1020)
goto out;
if (cascade_irq < 32 || cascade_irq >= NR_IRQS) {
do_bad_IRQ(cascade_irq, desc);
goto out;
}

cascade_irq += chip_data->irq_offset;
generic_handle_irq(cascade_irq);

out:
/* primary controller unmasking */
chip->unmask(irq);
}

static struct irq_chip gic_chip = {
.name = "GIC",
.ack = gic_ack_irq,
Expand All @@ -105,15 +166,29 @@ static struct irq_chip gic_chip = {
#endif
};

void __init gic_dist_init(void __iomem *base)
void __init gic_cascade_irq(unsigned int gic_nr, unsigned int irq)
{
if (gic_nr >= MAX_GIC_NR)
BUG();
if (set_irq_data(irq, &gic_data[gic_nr]) != 0)
BUG();
set_irq_chained_handler(irq, gic_handle_cascade_irq);
}

void __init gic_dist_init(unsigned int gic_nr, void __iomem *base,
unsigned int irq_start)
{
unsigned int max_irq, i;
u32 cpumask = 1 << smp_processor_id();

if (gic_nr >= MAX_GIC_NR)
BUG();

cpumask |= cpumask << 8;
cpumask |= cpumask << 16;

gic_dist_base = base;
gic_data[gic_nr].dist_base = base;
gic_data[gic_nr].irq_offset = (irq_start - 1) & ~31;

writel(0, base + GIC_DIST_CTRL);

Expand Down Expand Up @@ -158,18 +233,23 @@ void __init gic_dist_init(void __iomem *base)
/*
* Setup the Linux IRQ subsystem.
*/
for (i = 29; i < max_irq; i++) {
for (i = irq_start; i < gic_data[gic_nr].irq_offset + max_irq; i++) {
set_irq_chip(i, &gic_chip);
set_irq_chip_data(i, &gic_data[gic_nr]);
set_irq_handler(i, handle_level_irq);
set_irq_flags(i, IRQF_VALID | IRQF_PROBE);
}

writel(1, base + GIC_DIST_CTRL);
}

void __cpuinit gic_cpu_init(void __iomem *base)
void __cpuinit gic_cpu_init(unsigned int gic_nr, void __iomem *base)
{
gic_cpu_base = base;
if (gic_nr >= MAX_GIC_NR)
BUG();

gic_data[gic_nr].cpu_base = base;

writel(0xf0, base + GIC_CPU_PRIMASK);
writel(1, base + GIC_CPU_CTRL);
}
Expand All @@ -179,6 +259,7 @@ void gic_raise_softirq(cpumask_t cpumask, unsigned int irq)
{
unsigned long map = *cpus_addr(cpumask);

writel(map << 16 | irq, gic_dist_base + GIC_DIST_SOFTINT);
/* this always happens on GIC0 */
writel(map << 16 | irq, gic_data[0].dist_base + GIC_DIST_SOFTINT);
}
#endif
2 changes: 1 addition & 1 deletion arch/arm/mach-realview/platsmp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -52,7 +52,7 @@ void __cpuinit platform_secondary_init(unsigned int cpu)
* core (e.g. timer irq), then they will not have been enabled
* for us: do so
*/
gic_cpu_init(__io_address(REALVIEW_GIC_CPU_BASE));
gic_cpu_init(0, __io_address(REALVIEW_GIC_CPU_BASE));

/*
* let the primary processor know we're out of the
Expand Down
4 changes: 2 additions & 2 deletions arch/arm/mach-realview/realview_eb.c
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Original file line number Diff line number Diff line change
Expand Up @@ -143,8 +143,8 @@ static void __init gic_init_irq(void)
writel(pldctrl, __io_address(REALVIEW_SYS_BASE) + 0xd8);
writel(0x00000000, __io_address(REALVIEW_SYS_LOCK));
#endif
gic_dist_init(__io_address(REALVIEW_GIC_DIST_BASE));
gic_cpu_init(__io_address(REALVIEW_GIC_CPU_BASE));
gic_dist_init(0, __io_address(REALVIEW_GIC_DIST_BASE), 29);
gic_cpu_init(0, __io_address(REALVIEW_GIC_CPU_BASE));
}

static void __init realview_eb_init(void)
Expand Down
5 changes: 3 additions & 2 deletions include/asm-arm/hardware/gic.h
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Original file line number Diff line number Diff line change
Expand Up @@ -33,8 +33,9 @@
#define GIC_DIST_SOFTINT 0xf00

#ifndef __ASSEMBLY__
void gic_dist_init(void __iomem *base);
void gic_cpu_init(void __iomem *base);
void gic_dist_init(unsigned int gic_nr, void __iomem *base, unsigned int irq_start);
void gic_cpu_init(unsigned int gic_nr, void __iomem *base);
void gic_cascade_irq(unsigned int gic_nr, unsigned int irq);
void gic_raise_softirq(cpumask_t cpumask, unsigned int irq);
#endif

Expand Down

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