metag: Internal and external irqchips

Meta core internal interrupts (from HWSTATMETA and friends) are vectored
onto the TR1 core trigger for the current thread. This is demultiplexed
in irq-metag.c to individual Linux IRQs for each internal interrupt.

External SoC interrupts (from HWSTATEXT and friends) are vectored onto
the TR2 core trigger for the current thread. This is demultiplexed in
irq-metag-ext.c to individual Linux IRQs for each external SoC interrupt.
The external irqchip has devicetree bindings for configuring the number
of irq banks and the type of masking available.

Signed-off-by: James Hogan <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: Grant Likely <[e-mail]>
Cc: Rob Herring <[e-mail]>
Cc: Rob Landley <[e-mail]>
Cc: Dom Cobley <[e-mail]>
Cc: Simon Arlott <[e-mail]>
Cc: Viresh Kumar <[e-mail]>
Cc: Maxime Ripard <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]

Documentation/devicetree/bindings/metag/meta-intc.txt

···
+* Meta External Trigger Controller Binding
+
+This binding specifies what properties must be available in the device tree
+representation of a Meta external trigger controller.
+
+Required properties:
+
+    - compatible: Specifies the compatibility list for the interrupt controller.
+      The type shall be <string> and the value shall include "img,meta-intc".
+
+    - num-banks: Specifies the number of interrupt banks (each of which can
+      handle 32 interrupt sources).
+
+    - interrupt-controller: The presence of this property identifies the node
+      as an interupt controller. No property value shall be defined.
+
+    - #interrupt-cells: Specifies the number of cells needed to encode an
+      interrupt source. The type shall be a <u32> and the value shall be 2.
+
+    - #address-cells: Specifies the number of cells needed to encode an
+      address. The type shall be <u32> and the value shall be 0. As such,
+      'interrupt-map' nodes do not have to specify a parent unit address.
+
+Optional properties:
+
+    - no-mask: The controller doesn't have any mask registers.
+
+* Interrupt Specifier Definition
+
+  Interrupt specifiers consists of 2 cells encoded as follows:
+
+    - <1st-cell>: The interrupt-number that identifies the interrupt source.
+
+    - <2nd-cell>: The Linux interrupt flags containing level-sense information,
+                  encoded as follows:
+                    1 = edge triggered
+                    4 = level-sensitive
+
+* Examples
+
+Example 1:
+
+	/*
+	 * Meta external trigger block
+	 */
+	intc: intc {
+		// This is an interrupt controller node.
+		interrupt-controller;
+
+		// No address cells so that 'interrupt-map' nodes which
+		// reference this interrupt controller node do not need a parent
+		// address specifier.
+		#address-cells = <0>;
+
+		// Two cells to encode interrupt sources.
+		#interrupt-cells = <2>;
+
+		// Number of interrupt banks
+		num-banks = <2>;
+
+		// No HWMASKEXT is available (specify on Chorus2 and Comet ES1)
+		no-mask;
+
+		// Compatible with Meta hardware trigger block.
+		compatible = "img,meta-intc";
+	};
+
+Example 2:
+
+	/*
+	 * An interrupt generating device that is wired to a Meta external
+	 * trigger block.
+	 */
+	uart1: uart@0x02004c00 {
+		// Interrupt source '5' that is level-sensitive.
+		// Note that there are only two cells as specified in the
+		// interrupt parent's '#interrupt-cells' property.
+		interrupts = <5 4 /* level */>;
+
+		// The interrupt controller that this device is wired to.
+		interrupt-parent = <&intc>;
+	};

MAINTAINERS

···
 F:	Documentation/metag/
 F:	Documentation/devicetree/bindings/metag/
 F:	drivers/clocksource/metag_generic.c
+F:	drivers/irqchip/irq-metag.c
+F:	drivers/irqchip/irq-metag-ext.c
 
 MICROBLAZE ARCHITECTURE
 M:	Michal Simek <[e-mail]>

arch/metag/kernel/irq.c

···
 #include <linux/kernel.h>
 #include <linux/interrupt.h>
 #include <linux/init.h>
+#include <linux/irqchip/metag-ext.h>
+#include <linux/irqchip/metag.h>
 #include <linux/irqdomain.h>
 #include <linux/ratelimit.h>
 
···
 		panic("init_IRQ: cannot add root IRQ domain");
 
 	irq_ctx_init(smp_processor_id());
+
+	init_internal_IRQ();
+	init_external_IRQ();
 
 	if (machine_desc->init_irq)
 		machine_desc->init_irq();

drivers/irqchip/Makefile

···
 obj-$(CONFIG_ARCH_BCM2835)		+= irq-bcm2835.o
+obj-$(CONFIG_METAG)			+= irq-metag-ext.o
+obj-$(CONFIG_METAG_PERFCOUNTER_IRQS)	+= irq-metag.o
 obj-$(CONFIG_ARCH_SUNXI)		+= irq-sunxi.o
 obj-$(CONFIG_VERSATILE_FPGA_IRQ)	+= irq-versatile-fpga.o
 obj-$(CONFIG_ARCH_SPEAR3XX)		+= spear-shirq.o

drivers/irqchip/irq-metag-ext.c

···
+/*
+ * Meta External interrupt code.
+ *
+ * Copyright (C) 2005-2012 Imagination Technologies Ltd.
+ *
+ * External interrupts on Meta are configured at two-levels, in the CPU core and
+ * in the external trigger block. Interrupts from SoC peripherals are
+ * multiplexed onto a single Meta CPU "trigger" - traditionally it has always
+ * been trigger 2 (TR2). For info on how de-multiplexing happens check out
+ * meta_intc_irq_demux().
+ */
+
+#include <linux/interrupt.h>
+#include <linux/irqchip/metag-ext.h>
+#include <linux/irqdomain.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+#include <linux/syscore_ops.h>
+
+#include <asm/irq.h>
+#include <asm/hwthread.h>
+
+#define HWSTAT_STRIDE 8
+#define HWVEC_BLK_STRIDE 0x1000
+
+/**
+ * struct meta_intc_priv - private meta external interrupt data
+ * @nr_banks:		Number of interrupt banks
+ * @domain:		IRQ domain for all banks of external IRQs
+ * @unmasked:		Record of unmasked IRQs
+ * @levels_altered:	Record of altered level bits
+ */
+struct meta_intc_priv {
+	unsigned int		nr_banks;
+	struct irq_domain	*domain;
+
+	unsigned long		unmasked[4];
+
+#ifdef CONFIG_METAG_SUSPEND_MEM
+	unsigned long		levels_altered[4];
+#endif
+};
+
+/* Private data for the one and only external interrupt controller */
+static struct meta_intc_priv meta_intc_priv;
+
+/**
+ * meta_intc_offset() - Get the offset into the bank of a hardware IRQ number
+ * @hw:		Hardware IRQ number (within external trigger block)
+ *
+ * Returns:	Bit offset into the IRQ's bank registers
+ */
+static unsigned int meta_intc_offset(irq_hw_number_t hw)
+{
+	return hw & 0x1f;
+}
+
+/**
+ * meta_intc_bank() - Get the bank number of a hardware IRQ number
+ * @hw:		Hardware IRQ number (within external trigger block)
+ *
+ * Returns:	Bank number indicating which register the IRQ's bits are
+ */
+static unsigned int meta_intc_bank(irq_hw_number_t hw)
+{
+	return hw >> 5;
+}
+
+/**
+ * meta_intc_stat_addr() - Get the address of a HWSTATEXT register
+ * @hw:		Hardware IRQ number (within external trigger block)
+ *
+ * Returns:	Address of a HWSTATEXT register containing the status bit for
+ *		the specified hardware IRQ number
+ */
+static void __iomem *meta_intc_stat_addr(irq_hw_number_t hw)
+{
+	return (void __iomem *)(HWSTATEXT +
+				HWSTAT_STRIDE * meta_intc_bank(hw));
+}
+
+/**
+ * meta_intc_level_addr() - Get the address of a HWLEVELEXT register
+ * @hw:		Hardware IRQ number (within external trigger block)
+ *
+ * Returns:	Address of a HWLEVELEXT register containing the sense bit for
+ *		the specified hardware IRQ number
+ */
+static void __iomem *meta_intc_level_addr(irq_hw_number_t hw)
+{
+	return (void __iomem *)(HWLEVELEXT +
+				HWSTAT_STRIDE * meta_intc_bank(hw));
+}
+
+/**
+ * meta_intc_mask_addr() - Get the address of a HWMASKEXT register
+ * @hw:		Hardware IRQ number (within external trigger block)
+ *
+ * Returns:	Address of a HWMASKEXT register containing the mask bit for the
+ *		specified hardware IRQ number
+ */
+static void __iomem *meta_intc_mask_addr(irq_hw_number_t hw)
+{
+	return (void __iomem *)(HWMASKEXT +
+				HWSTAT_STRIDE * meta_intc_bank(hw));
+}
+
+/**
+ * meta_intc_vec_addr() - Get the vector address of a hardware interrupt
+ * @hw:		Hardware IRQ number (within external trigger block)
+ *
+ * Returns:	Address of a HWVECEXT register controlling the core trigger to
+ *		vector the IRQ onto
+ */
+static inline void __iomem *meta_intc_vec_addr(irq_hw_number_t hw)
+{
+	return (void __iomem *)(HWVEC0EXT +
+				HWVEC_BLK_STRIDE * meta_intc_bank(hw) +
+				HWVECnEXT_STRIDE * meta_intc_offset(hw));
+}
+
+/**
+ * meta_intc_startup_irq() - set up an external irq
+ * @data:	data for the external irq to start up
+ *
+ * Multiplex interrupts for irq onto TR2. Clear any pending interrupts and
+ * unmask irq, both using the appropriate callbacks.
+ */
+static unsigned int meta_intc_startup_irq(struct irq_data *data)
+{
+	irq_hw_number_t hw = data->hwirq;
+	void __iomem *vec_addr = meta_intc_vec_addr(hw);
+	int thread = hard_processor_id();
+
+	/* Perform any necessary acking. */
+	if (data->chip->irq_ack)
+		data->chip->irq_ack(data);
+
+	/* Wire up this interrupt to the core with HWVECxEXT. */
+	metag_out32(TBI_TRIG_VEC(TBID_SIGNUM_TR2(thread)), vec_addr);
+
+	/* Perform any necessary unmasking. */
+	data->chip->irq_unmask(data);
+
+	return 0;
+}
+
+/**
+ * meta_intc_shutdown_irq() - turn off an external irq
+ * @data:	data for the external irq to turn off
+ *
+ * Mask irq using the appropriate callback and stop muxing it onto TR2.
+ */
+static void meta_intc_shutdown_irq(struct irq_data *data)
+{
+	irq_hw_number_t hw = data->hwirq;
+	void __iomem *vec_addr = meta_intc_vec_addr(hw);
+
+	/* Mask the IRQ */
+	data->chip->irq_mask(data);
+
+	/*
+	 * Disable the IRQ at the core by removing the interrupt from
+	 * the HW vector mapping.
+	 */
+	metag_out32(0, vec_addr);
+}
+
+/**
+ * meta_intc_ack_irq() - acknowledge an external irq
+ * @data:	data for the external irq to ack
+ *
+ * Clear down an edge interrupt in the status register.
+ */
+static void meta_intc_ack_irq(struct irq_data *data)
+{
+	irq_hw_number_t hw = data->hwirq;
+	unsigned int bit = 1 << meta_intc_offset(hw);
+	void __iomem *stat_addr = meta_intc_stat_addr(hw);
+
+	/* Ack the int, if it is still 'on'.
+	 * NOTE - this only works for edge triggered interrupts.
+	 */
+	if (metag_in32(stat_addr) & bit)
+		metag_out32(bit, stat_addr);
+}
+
+/**
+ * record_irq_is_masked() - record the IRQ masked so it doesn't get handled
+ * @data:	data for the external irq to record
+ *
+ * This should get called whenever an external IRQ is masked (by whichever
+ * callback is used). It records the IRQ masked so that it doesn't get handled
+ * if it still shows up in the status register.
+ */
+static void record_irq_is_masked(struct irq_data *data)
+{
+	struct meta_intc_priv *priv = &meta_intc_priv;
+	irq_hw_number_t hw = data->hwirq;
+
+	clear_bit(meta_intc_offset(hw), &priv->unmasked[meta_intc_bank(hw)]);
+}
+
+/**
+ * record_irq_is_unmasked() - record the IRQ unmasked so it can be handled
+ * @data:	data for the external irq to record
+ *
+ * This should get called whenever an external IRQ is unmasked (by whichever
+ * callback is used). It records the IRQ unmasked so that it gets handled if it
+ * shows up in the status register.
+ */
+static void record_irq_is_unmasked(struct irq_data *data)
+{
+	struct meta_intc_priv *priv = &meta_intc_priv;
+	irq_hw_number_t hw = data->hwirq;
+
+	set_bit(meta_intc_offset(hw), &priv->unmasked[meta_intc_bank(hw)]);
+}
+
+/*
+ * For use by wrapper IRQ drivers
+ */
+
+/**
+ * meta_intc_mask_irq_simple() - minimal mask used by wrapper IRQ drivers
+ * @data:	data for the external irq being masked
+ *
+ * This should be called by any wrapper IRQ driver mask functions. it doesn't do
+ * any masking but records the IRQ as masked so that the core code knows the
+ * mask has taken place. It is the callers responsibility to ensure that the IRQ
+ * won't trigger an interrupt to the core.
+ */
+void meta_intc_mask_irq_simple(struct irq_data *data)
+{
+	record_irq_is_masked(data);
+}
+
+/**
+ * meta_intc_unmask_irq_simple() - minimal unmask used by wrapper IRQ drivers
+ * @data:	data for the external irq being unmasked
+ *
+ * This should be called by any wrapper IRQ driver unmask functions. it doesn't
+ * do any unmasking but records the IRQ as unmasked so that the core code knows
+ * the unmask has taken place. It is the callers responsibility to ensure that
+ * the IRQ can now trigger an interrupt to the core.
+ */
+void meta_intc_unmask_irq_simple(struct irq_data *data)
+{
+	record_irq_is_unmasked(data);
+}
+
+
+/**
+ * meta_intc_mask_irq() - mask an external irq using HWMASKEXT
+ * @data:	data for the external irq to mask
+ *
+ * This is a default implementation of a mask function which makes use of the
+ * HWMASKEXT registers available in newer versions.
+ *
+ * Earlier versions without these registers should use SoC level IRQ masking
+ * which call the meta_intc_*_simple() functions above, or if that isn't
+ * available should use the fallback meta_intc_*_nomask() functions below.
+ */
+static void meta_intc_mask_irq(struct irq_data *data)
+{
+	irq_hw_number_t hw = data->hwirq;
+	unsigned int bit = 1 << meta_intc_offset(hw);
+	void __iomem *mask_addr = meta_intc_mask_addr(hw);
+	unsigned long flags;
+
+	record_irq_is_masked(data);
+
+	/* update the interrupt mask */
+	__global_lock2(flags);
+	metag_out32(metag_in32(mask_addr) & ~bit, mask_addr);
+	__global_unlock2(flags);
+}
+
+/**
+ * meta_intc_unmask_irq() - unmask an external irq using HWMASKEXT
+ * @data:	data for the external irq to unmask
+ *
+ * This is a default implementation of an unmask function which makes use of the
+ * HWMASKEXT registers available on new versions. It should be paired with
+ * meta_intc_mask_irq() above.
+ */
+static void meta_intc_unmask_irq(struct irq_data *data)
+{
+	irq_hw_number_t hw = data->hwirq;
+	unsigned int bit = 1 << meta_intc_offset(hw);
+	void __iomem *mask_addr = meta_intc_mask_addr(hw);
+	unsigned long flags;
+
+	record_irq_is_unmasked(data);
+
+	/* update the interrupt mask */
+	__global_lock2(flags);
+	metag_out32(metag_in32(mask_addr) | bit, mask_addr);
+	__global_unlock2(flags);
+}
+
+/**
+ * meta_intc_mask_irq_nomask() - mask an external irq by unvectoring
+ * @data:	data for the external irq to mask
+ *
+ * This is the version of the mask function for older versions which don't have
+ * HWMASKEXT registers, or a SoC level means of masking IRQs. Instead the IRQ is
+ * unvectored from the core and retriggered if necessary later.
+ */
+static void meta_intc_mask_irq_nomask(struct irq_data *data)
+{
+	irq_hw_number_t hw = data->hwirq;
+	void __iomem *vec_addr = meta_intc_vec_addr(hw);
+
+	record_irq_is_masked(data);
+
+	/* there is no interrupt mask, so unvector the interrupt */
+	metag_out32(0, vec_addr);
+}
+
+/**
+ * meta_intc_unmask_edge_irq_nomask() - unmask an edge irq by revectoring
+ * @data:	data for the external irq to unmask
+ *
+ * This is the version of the unmask function for older versions which don't
+ * have HWMASKEXT registers, or a SoC level means of masking IRQs. Instead the
+ * IRQ is revectored back to the core and retriggered if necessary.
+ *
+ * The retriggering done by this function is specific to edge interrupts.
+ */
+static void meta_intc_unmask_edge_irq_nomask(struct irq_data *data)
+{
+	irq_hw_number_t hw = data->hwirq;
+	unsigned int bit = 1 << meta_intc_offset(hw);
+	void __iomem *stat_addr = meta_intc_stat_addr(hw);
+	void __iomem *vec_addr = meta_intc_vec_addr(hw);
+	unsigned int thread = hard_processor_id();
+
+	record_irq_is_unmasked(data);
+
+	/* there is no interrupt mask, so revector the interrupt */
+	metag_out32(TBI_TRIG_VEC(TBID_SIGNUM_TR2(thread)), vec_addr);
+
+	/*
+	 * Re-trigger interrupt
+	 *
+	 * Writing a 1 toggles, and a 0->1 transition triggers. We only
+	 * retrigger if the status bit is already set, which means we
+	 * need to clear it first. Retriggering is fundamentally racy
+	 * because if the interrupt fires again after we clear it we
+	 * could end up clearing it again and the interrupt handler
+	 * thinking it hasn't fired. Therefore we need to keep trying to
+	 * retrigger until the bit is set.
+	 */
+	if (metag_in32(stat_addr) & bit) {
+		metag_out32(bit, stat_addr);
+		while (!(metag_in32(stat_addr) & bit))
+			metag_out32(bit, stat_addr);
+	}
+}
+
+/**
+ * meta_intc_unmask_level_irq_nomask() - unmask a level irq by revectoring
+ * @data:	data for the external irq to unmask
+ *
+ * This is the version of the unmask function for older versions which don't
+ * have HWMASKEXT registers, or a SoC level means of masking IRQs. Instead the
+ * IRQ is revectored back to the core and retriggered if necessary.
+ *
+ * The retriggering done by this function is specific to level interrupts.
+ */
+static void meta_intc_unmask_level_irq_nomask(struct irq_data *data)
+{
+	irq_hw_number_t hw = data->hwirq;
+	unsigned int bit = 1 << meta_intc_offset(hw);
+	void __iomem *stat_addr = meta_intc_stat_addr(hw);
+	void __iomem *vec_addr = meta_intc_vec_addr(hw);
+	unsigned int thread = hard_processor_id();
+
+	record_irq_is_unmasked(data);
+
+	/* there is no interrupt mask, so revector the interrupt */
+	metag_out32(TBI_TRIG_VEC(TBID_SIGNUM_TR2(thread)), vec_addr);
+
+	/* Re-trigger interrupt */
+	/* Writing a 1 triggers interrupt */
+	if (metag_in32(stat_addr) & bit)
+		metag_out32(bit, stat_addr);
+}
+
+/**
+ * meta_intc_irq_set_type() - set the type of an external irq
+ * @data:	data for the external irq to set the type of
+ * @flow_type:	new irq flow type
+ *
+ * Set the flow type of an external interrupt. This updates the irq chip and irq
+ * handler depending on whether the irq is edge or level sensitive (the polarity
+ * is ignored), and also sets up the bit in HWLEVELEXT so the hardware knows
+ * when to trigger.
+ */
+static int meta_intc_irq_set_type(struct irq_data *data, unsigned int flow_type)
+{
+#ifdef CONFIG_METAG_SUSPEND_MEM
+	struct meta_intc_priv *priv = &meta_intc_priv;
+#endif
+	unsigned int irq = data->irq;
+	irq_hw_number_t hw = data->hwirq;
+	unsigned int bit = 1 << meta_intc_offset(hw);
+	void __iomem *level_addr = meta_intc_level_addr(hw);
+	unsigned long flags;
+	unsigned int level;
+
+	/* update the chip/handler */
+	if (flow_type & IRQ_TYPE_LEVEL_MASK)
+		__irq_set_chip_handler_name_locked(irq, &meta_intc_level_chip,
+						   handle_level_irq, NULL);
+	else
+		__irq_set_chip_handler_name_locked(irq, &meta_intc_edge_chip,
+						   handle_edge_irq, NULL);
+
+	/* and clear/set the bit in HWLEVELEXT */
+	__global_lock2(flags);
+	level = metag_in32(level_addr);
+	if (flow_type & IRQ_TYPE_LEVEL_MASK)
+		level |= bit;
+	else
+		level &= ~bit;
+	metag_out32(level, level_addr);
+#ifdef CONFIG_METAG_SUSPEND_MEM
+	priv->levels_altered[meta_intc_bank(hw)] |= bit;
+#endif
+	__global_unlock2(flags);
+
+	return 0;
+}
+
+/**
+ * meta_intc_irq_demux() - external irq de-multiplexer
+ * @irq:	the virtual interrupt number
+ * @desc:	the interrupt description structure for this irq
+ *
+ * The cpu receives an interrupt on TR2 when a SoC interrupt has occurred. It is
+ * this function's job to demux this irq and figure out exactly which external
+ * irq needs servicing.
+ *
+ * Whilst using TR2 to detect external interrupts is a software convention it is
+ * (hopefully) unlikely to change.
+ */
+static void meta_intc_irq_demux(unsigned int irq, struct irq_desc *desc)
+{
+	struct meta_intc_priv *priv = &meta_intc_priv;
+	irq_hw_number_t hw;
+	unsigned int bank, irq_no, status;
+	void __iomem *stat_addr = meta_intc_stat_addr(0);
+
+	/*
+	 * Locate which interrupt has caused our handler to run.
+	 */
+	for (bank = 0; bank < priv->nr_banks; ++bank) {
+		/* Which interrupts are currently pending in this bank? */
+recalculate:
+		status = metag_in32(stat_addr) & priv->unmasked[bank];
+
+		for (hw = bank*32; status; status >>= 1, ++hw) {
+			if (status & 0x1) {
+				/*
+				 * Map the hardware IRQ number to a virtual
+				 * Linux IRQ number.
+				 */
+				irq_no = irq_linear_revmap(priv->domain, hw);
+
+				/*
+				 * Only fire off external interrupts that are
+				 * registered to be handled by the kernel.
+				 * Other external interrupts are probably being
+				 * handled by other Meta hardware threads.
+				 */
+				generic_handle_irq(irq_no);
+
+				/*
+				 * The handler may have re-enabled interrupts
+				 * which could have caused a nested invocation
+				 * of this code and make the copy of the
+				 * status register we are using invalid.
+				 */
+				goto recalculate;
+			}
+		}
+		stat_addr += HWSTAT_STRIDE;
+	}
+}
+
+#ifdef CONFIG_SMP
+/**
+ * meta_intc_set_affinity() - set the affinity for an interrupt
+ * @data:	data for the external irq to set the affinity of
+ * @cpumask:	cpu mask representing cpus which can handle the interrupt
+ * @force:	whether to force (ignored)
+ *
+ * Revector the specified external irq onto a specific cpu's TR2 trigger, so
+ * that that cpu tends to be the one who handles it.
+ */
+static int meta_intc_set_affinity(struct irq_data *data,
+				  const struct cpumask *cpumask, bool force)
+{
+	irq_hw_number_t hw = data->hwirq;
+	void __iomem *vec_addr = meta_intc_vec_addr(hw);
+	unsigned int cpu, thread;
+
+	/*
+	 * Wire up this interrupt from HWVECxEXT to the Meta core.
+	 *
+	 * Note that we can't wire up HWVECxEXT to interrupt more than
+	 * one cpu (the interrupt code doesn't support it), so we just
+	 * pick the first cpu we find in 'cpumask'.
+	 */
+	cpu = cpumask_any(cpumask);
+	thread = cpu_2_hwthread_id[cpu];
+
+	metag_out32(TBI_TRIG_VEC(TBID_SIGNUM_TR2(thread)), vec_addr);
+
+	return 0;
+}
+#else
+#define meta_intc_set_affinity	NULL
+#endif
+
+#ifdef CONFIG_PM_SLEEP
+#define META_INTC_CHIP_FLAGS	(IRQCHIP_MASK_ON_SUSPEND \
+				| IRQCHIP_SKIP_SET_WAKE)
+#else
+#define META_INTC_CHIP_FLAGS	0
+#endif
+
+/* public edge/level irq chips which SoCs can override */
+
+struct irq_chip meta_intc_edge_chip = {
+	.irq_startup		= meta_intc_startup_irq,
+	.irq_shutdown		= meta_intc_shutdown_irq,
+	.irq_ack		= meta_intc_ack_irq,
+	.irq_mask		= meta_intc_mask_irq,
+	.irq_unmask		= meta_intc_unmask_irq,
+	.irq_set_type		= meta_intc_irq_set_type,
+	.irq_set_affinity	= meta_intc_set_affinity,
+	.flags			= META_INTC_CHIP_FLAGS,
+};
+
+struct irq_chip meta_intc_level_chip = {
+	.irq_startup		= meta_intc_startup_irq,
+	.irq_shutdown		= meta_intc_shutdown_irq,
+	.irq_set_type		= meta_intc_irq_set_type,
+	.irq_mask		= meta_intc_mask_irq,
+	.irq_unmask		= meta_intc_unmask_irq,
+	.irq_set_affinity	= meta_intc_set_affinity,
+	.flags			= META_INTC_CHIP_FLAGS,
+};
+
+/**
+ * meta_intc_map() - map an external irq
+ * @d:		irq domain of external trigger block
+ * @irq:	virtual irq number
+ * @hw:		hardware irq number within external trigger block
+ *
+ * This sets up a virtual irq for a specified hardware interrupt. The irq chip
+ * and handler is configured, using the HWLEVELEXT registers to determine
+ * edge/level flow type. These registers will have been set when the irq type is
+ * set (or set to a default at init time).
+ */
+static int meta_intc_map(struct irq_domain *d, unsigned int irq,
+			 irq_hw_number_t hw)
+{
+	unsigned int bit = 1 << meta_intc_offset(hw);
+	void __iomem *level_addr = meta_intc_level_addr(hw);
+
+	/* Go by the current sense in the HWLEVELEXT register */
+	if (metag_in32(level_addr) & bit)
+		irq_set_chip_and_handler(irq, &meta_intc_level_chip,
+					 handle_level_irq);
+	else
+		irq_set_chip_and_handler(irq, &meta_intc_edge_chip,
+					 handle_edge_irq);
+	return 0;
+}
+
+static const struct irq_domain_ops meta_intc_domain_ops = {
+	.map = meta_intc_map,
+	.xlate = irq_domain_xlate_twocell,
+};
+
+#ifdef CONFIG_METAG_SUSPEND_MEM
+
+/**
+ * struct meta_intc_context - suspend context
+ * @levels:	State of HWLEVELEXT registers
+ * @masks:	State of HWMASKEXT registers
+ * @vectors:	State of HWVECEXT registers
+ * @txvecint:	State of TxVECINT registers
+ *
+ * This structure stores the IRQ state across suspend.
+ */
+struct meta_intc_context {
+	u32 levels[4];
+	u32 masks[4];
+	u8 vectors[4*32];
+
+	u8 txvecint[4][4];
+};
+
+/* suspend context */
+static struct meta_intc_context *meta_intc_context;
+
+/**
+ * meta_intc_suspend() - store irq state
+ *
+ * To avoid interfering with other threads we only save the IRQ state of IRQs in
+ * use by Linux.
+ */
+static int meta_intc_suspend(void)
+{
+	struct meta_intc_priv *priv = &meta_intc_priv;
+	int i, j;
+	irq_hw_number_t hw;
+	unsigned int bank;
+	unsigned long flags;
+	struct meta_intc_context *context;
+	void __iomem *level_addr, *mask_addr, *vec_addr;
+	u32 mask, bit;
+
+	context = kzalloc(sizeof(*context), GFP_ATOMIC);
+	if (!context)
+		return -ENOMEM;
+
+	hw = 0;
+	level_addr = meta_intc_level_addr(0);
+	mask_addr = meta_intc_mask_addr(0);
+	for (bank = 0; bank < priv->nr_banks; ++bank) {
+		vec_addr = meta_intc_vec_addr(hw);
+
+		/* create mask of interrupts in use */
+		mask = 0;
+		for (bit = 1; bit; bit <<= 1) {
+			i = irq_linear_revmap(priv->domain, hw);
+			/* save mapped irqs which are enabled or have actions */
+			if (i && (!irqd_irq_disabled(irq_get_irq_data(i)) ||
+				  irq_has_action(i))) {
+				mask |= bit;
+
+				/* save trigger vector */
+				context->vectors[hw] = metag_in32(vec_addr);
+			}
+
+			++hw;
+			vec_addr += HWVECnEXT_STRIDE;
+		}
+
+		/* save level state if any IRQ levels altered */
+		if (priv->levels_altered[bank])
+			context->levels[bank] = metag_in32(level_addr);
+		/* save mask state if any IRQs in use */
+		if (mask)
+			context->masks[bank] = metag_in32(mask_addr);
+
+		level_addr += HWSTAT_STRIDE;
+		mask_addr += HWSTAT_STRIDE;
+	}
+
+	/* save trigger matrixing */
+	__global_lock2(flags);
+	for (i = 0; i < 4; ++i)
+		for (j = 0; j < 4; ++j)
+			context->txvecint[i][j] = metag_in32(T0VECINT_BHALT +
+							     TnVECINT_STRIDE*i +
+							     8*j);
+	__global_unlock2(flags);
+
+	meta_intc_context = context;
+	return 0;
+}
+
+/**
+ * meta_intc_resume() - restore saved irq state
+ *
+ * Restore the saved IRQ state and drop it.
+ */
+static void meta_intc_resume(void)
+{
+	struct meta_intc_priv *priv = &meta_intc_priv;
+	int i, j;
+	irq_hw_number_t hw;
+	unsigned int bank;
+	unsigned long flags;
+	struct meta_intc_context *context = meta_intc_context;
+	void __iomem *level_addr, *mask_addr, *vec_addr;
+	u32 mask, bit, tmp;
+
+	meta_intc_context = NULL;
+
+	hw = 0;
+	level_addr = meta_intc_level_addr(0);
+	mask_addr = meta_intc_mask_addr(0);
+	for (bank = 0; bank < priv->nr_banks; ++bank) {
+		vec_addr = meta_intc_vec_addr(hw);
+
+		/* create mask of interrupts in use */
+		mask = 0;
+		for (bit = 1; bit; bit <<= 1) {
+			i = irq_linear_revmap(priv->domain, hw);
+			/* restore mapped irqs, enabled or with actions */
+			if (i && (!irqd_irq_disabled(irq_get_irq_data(i)) ||
+				  irq_has_action(i))) {
+				mask |= bit;
+
+				/* restore trigger vector */
+				metag_out32(context->vectors[hw], vec_addr);
+			}
+
+			++hw;
+			vec_addr += HWVECnEXT_STRIDE;
+		}
+
+		if (mask) {
+			/* restore mask state */
+			__global_lock2(flags);
+			tmp = metag_in32(mask_addr);
+			tmp = (tmp & ~mask) | (context->masks[bank] & mask);
+			metag_out32(tmp, mask_addr);
+			__global_unlock2(flags);
+		}
+
+		mask = priv->levels_altered[bank];
+		if (mask) {
+			/* restore level state */
+			__global_lock2(flags);
+			tmp = metag_in32(level_addr);
+			tmp = (tmp & ~mask) | (context->levels[bank] & mask);
+			metag_out32(tmp, level_addr);
+			__global_unlock2(flags);
+		}
+
+		level_addr += HWSTAT_STRIDE;
+		mask_addr += HWSTAT_STRIDE;
+	}
+
+	/* restore trigger matrixing */
+	__global_lock2(flags);
+	for (i = 0; i < 4; ++i) {
+		for (j = 0; j < 4; ++j) {
+			metag_out32(context->txvecint[i][j],
+				    T0VECINT_BHALT +
+				    TnVECINT_STRIDE*i +
+				    8*j);
+		}
+	}
+	__global_unlock2(flags);
+
+	kfree(context);
+}
+
+static struct syscore_ops meta_intc_syscore_ops = {
+	.suspend = meta_intc_suspend,
+	.resume = meta_intc_resume,
+};
+
+static void __init meta_intc_init_syscore_ops(struct meta_intc_priv *priv)
+{
+	register_syscore_ops(&meta_intc_syscore_ops);
+}
+#else
+#define meta_intc_init_syscore_ops(priv) do {} while (0)
+#endif
+
+/**
+ * meta_intc_init_cpu() - register with a Meta cpu
+ * @priv:	private interrupt controller data
+ * @cpu:	the CPU to register on
+ *
+ * Configure @cpu's TR2 irq so that we can demux external irqs.
+ */
+static void __init meta_intc_init_cpu(struct meta_intc_priv *priv, int cpu)
+{
+	unsigned int thread = cpu_2_hwthread_id[cpu];
+	unsigned int signum = TBID_SIGNUM_TR2(thread);
+	int irq = tbisig_map(signum);
+
+	/* Register the multiplexed IRQ handler */
+	irq_set_chained_handler(irq, meta_intc_irq_demux);
+	irq_set_irq_type(irq, IRQ_TYPE_LEVEL_LOW);
+}
+
+/**
+ * meta_intc_no_mask() - indicate lack of HWMASKEXT registers
+ *
+ * Called from SoC code (or init code below) to dynamically indicate the lack of
+ * HWMASKEXT registers (for example depending on some SoC revision register).
+ * This alters the irq mask and unmask callbacks to use the fallback
+ * unvectoring/retriggering technique instead of using HWMASKEXT registers.
+ */
+void __init meta_intc_no_mask(void)
+{
+	meta_intc_edge_chip.irq_mask	= meta_intc_mask_irq_nomask;
+	meta_intc_edge_chip.irq_unmask	= meta_intc_unmask_edge_irq_nomask;
+	meta_intc_level_chip.irq_mask	= meta_intc_mask_irq_nomask;
+	meta_intc_level_chip.irq_unmask	= meta_intc_unmask_level_irq_nomask;
+}
+
+/**
+ * init_external_IRQ() - initialise the external irq controller
+ *
+ * Set up the external irq controller using device tree properties. This is
+ * called from init_IRQ().
+ */
+int __init init_external_IRQ(void)
+{
+	struct meta_intc_priv *priv = &meta_intc_priv;
+	struct device_node *node;
+	int ret, cpu;
+	u32 val;
+	bool no_masks = false;
+
+	node = of_find_compatible_node(NULL, NULL, "img,meta-intc");
+	if (!node)
+		return -ENOENT;
+
+	/* Get number of banks */
+	ret = of_property_read_u32(node, "num-banks", &val);
+	if (ret) {
+		pr_err("meta-intc: No num-banks property found\n");
+		return ret;
+	}
+	if (val < 1 || val > 4) {
+		pr_err("meta-intc: num-banks (%u) out of range\n", val);
+		return -EINVAL;
+	}
+	priv->nr_banks = val;
+
+	/* Are any mask registers present? */
+	if (of_get_property(node, "no-mask", NULL))
+		no_masks = true;
+
+	/* No HWMASKEXT registers present? */
+	if (no_masks)
+		meta_intc_no_mask();
+
+	/* Set up an IRQ domain */
+	/*
+	 * This is a legacy IRQ domain for now until all the platform setup code
+	 * has been converted to devicetree.
+	 */
+	priv->domain = irq_domain_add_linear(node, priv->nr_banks*32,
+					     &meta_intc_domain_ops, priv);
+	if (unlikely(!priv->domain)) {
+		pr_err("meta-intc: cannot add IRQ domain\n");
+		return -ENOMEM;
+	}
+
+	/* Setup TR2 for all cpus. */
+	for_each_possible_cpu(cpu)
+		meta_intc_init_cpu(priv, cpu);
+
+	/* Set up system suspend/resume callbacks */
+	meta_intc_init_syscore_ops(priv);
+
+	pr_info("meta-intc: External IRQ controller initialised (%u IRQs)\n",
+		priv->nr_banks*32);
+
+	return 0;
+}

drivers/irqchip/irq-metag.c

···
+/*
+ * Meta internal (HWSTATMETA) interrupt code.
+ *
+ * Copyright (C) 2011-2012 Imagination Technologies Ltd.
+ *
+ * This code is based on the code in SoC/common/irq.c and SoC/comet/irq.c
+ * The code base could be generalised/merged as a lot of the functionality is
+ * similar. Until this is done, we try to keep the code simple here.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irqdomain.h>
+
+#include <asm/irq.h>
+#include <asm/hwthread.h>
+
+#define PERF0VECINT		0x04820580
+#define PERF1VECINT		0x04820588
+#define PERF0TRIG_OFFSET	16
+#define PERF1TRIG_OFFSET	17
+
+/**
+ * struct metag_internal_irq_priv - private meta internal interrupt data
+ * @domain:		IRQ domain for all internal Meta IRQs (HWSTATMETA)
+ * @unmasked:		Record of unmasked IRQs
+ */
+struct metag_internal_irq_priv {
+	struct irq_domain	*domain;
+
+	unsigned long		unmasked;
+};
+
+/* Private data for the one and only internal interrupt controller */
+static struct metag_internal_irq_priv metag_internal_irq_priv;
+
+static unsigned int metag_internal_irq_startup(struct irq_data *data);
+static void metag_internal_irq_shutdown(struct irq_data *data);
+static void metag_internal_irq_ack(struct irq_data *data);
+static void metag_internal_irq_mask(struct irq_data *data);
+static void metag_internal_irq_unmask(struct irq_data *data);
+#ifdef CONFIG_SMP
+static int metag_internal_irq_set_affinity(struct irq_data *data,
+			const struct cpumask *cpumask, bool force);
+#endif
+
+static struct irq_chip internal_irq_edge_chip = {
+	.name = "HWSTATMETA-IRQ",
+	.irq_startup = metag_internal_irq_startup,
+	.irq_shutdown = metag_internal_irq_shutdown,
+	.irq_ack = metag_internal_irq_ack,
+	.irq_mask = metag_internal_irq_mask,
+	.irq_unmask = metag_internal_irq_unmask,
+#ifdef CONFIG_SMP
+	.irq_set_affinity = metag_internal_irq_set_affinity,
+#endif
+};
+
+/*
+ *	metag_hwvec_addr - get the address of *VECINT regs of irq
+ *
+ *	This function is a table of supported triggers on HWSTATMETA
+ *	Could do with a structure, but better keep it simple. Changes
+ *	in this code should be rare.
+ */
+static inline void __iomem *metag_hwvec_addr(irq_hw_number_t hw)
+{
+	void __iomem *addr;
+
+	switch (hw) {
+	case PERF0TRIG_OFFSET:
+		addr = (void __iomem *)PERF0VECINT;
+		break;
+	case PERF1TRIG_OFFSET:
+		addr = (void __iomem *)PERF1VECINT;
+		break;
+	default:
+		addr = NULL;
+		break;
+	}
+	return addr;
+}
+
+/*
+ *	metag_internal_startup - setup an internal irq
+ *	@irq:	the irq to startup
+ *
+ *	Multiplex interrupts for @irq onto TR1. Clear any pending
+ *	interrupts.
+ */
+static unsigned int metag_internal_irq_startup(struct irq_data *data)
+{
+	/* Clear (toggle) the bit in HWSTATMETA for our interrupt. */
+	metag_internal_irq_ack(data);
+
+	/* Enable the interrupt by unmasking it */
+	metag_internal_irq_unmask(data);
+
+	return 0;
+}
+
+/*
+ *	metag_internal_irq_shutdown - turn off the irq
+ *	@irq:	the irq number to turn off
+ *
+ *	Mask @irq and clear any pending interrupts.
+ *	Stop muxing @irq onto TR1.
+ */
+static void metag_internal_irq_shutdown(struct irq_data *data)
+{
+	/* Disable the IRQ at the core by masking it. */
+	metag_internal_irq_mask(data);
+
+	/* Clear (toggle) the bit in HWSTATMETA for our interrupt. */
+	metag_internal_irq_ack(data);
+}
+
+/*
+ *	metag_internal_irq_ack - acknowledge irq
+ *	@irq:	the irq to ack
+ */
+static void metag_internal_irq_ack(struct irq_data *data)
+{
+	irq_hw_number_t hw = data->hwirq;
+	unsigned int bit = 1 << hw;
+
+	if (metag_in32(HWSTATMETA) & bit)
+		metag_out32(bit, HWSTATMETA);
+}
+
+/**
+ * metag_internal_irq_mask() - mask an internal irq by unvectoring
+ * @data:	data for the internal irq to mask
+ *
+ * HWSTATMETA has no mask register. Instead the IRQ is unvectored from the core
+ * and retriggered if necessary later.
+ */
+static void metag_internal_irq_mask(struct irq_data *data)
+{
+	struct metag_internal_irq_priv *priv = &metag_internal_irq_priv;
+	irq_hw_number_t hw = data->hwirq;
+	void __iomem *vec_addr = metag_hwvec_addr(hw);
+
+	clear_bit(hw, &priv->unmasked);
+
+	/* there is no interrupt mask, so unvector the interrupt */
+	metag_out32(0, vec_addr);
+}
+
+/**
+ * meta_intc_unmask_edge_irq_nomask() - unmask an edge irq by revectoring
+ * @data:	data for the internal irq to unmask
+ *
+ * HWSTATMETA has no mask register. Instead the IRQ is revectored back to the
+ * core and retriggered if necessary.
+ */
+static void metag_internal_irq_unmask(struct irq_data *data)
+{
+	struct metag_internal_irq_priv *priv = &metag_internal_irq_priv;
+	irq_hw_number_t hw = data->hwirq;
+	unsigned int bit = 1 << hw;
+	void __iomem *vec_addr = metag_hwvec_addr(hw);
+	unsigned int thread = hard_processor_id();
+
+	set_bit(hw, &priv->unmasked);
+
+	/* there is no interrupt mask, so revector the interrupt */
+	metag_out32(TBI_TRIG_VEC(TBID_SIGNUM_TR1(thread)), vec_addr);
+
+	/*
+	 * Re-trigger interrupt
+	 *
+	 * Writing a 1 toggles, and a 0->1 transition triggers. We only
+	 * retrigger if the status bit is already set, which means we
+	 * need to clear it first. Retriggering is fundamentally racy
+	 * because if the interrupt fires again after we clear it we
+	 * could end up clearing it again and the interrupt handler
+	 * thinking it hasn't fired. Therefore we need to keep trying to
+	 * retrigger until the bit is set.
+	 */
+	if (metag_in32(HWSTATMETA) & bit) {
+		metag_out32(bit, HWSTATMETA);
+		while (!(metag_in32(HWSTATMETA) & bit))
+			metag_out32(bit, HWSTATMETA);
+	}
+}
+
+#ifdef CONFIG_SMP
+/*
+ *	metag_internal_irq_set_affinity - set the affinity for an interrupt
+ */
+static int metag_internal_irq_set_affinity(struct irq_data *data,
+			const struct cpumask *cpumask, bool force)
+{
+	unsigned int cpu, thread;
+	irq_hw_number_t hw = data->hwirq;
+	/*
+	 * Wire up this interrupt from *VECINT to the Meta core.
+	 *
+	 * Note that we can't wire up *VECINT to interrupt more than
+	 * one cpu (the interrupt code doesn't support it), so we just
+	 * pick the first cpu we find in 'cpumask'.
+	 */
+	cpu = cpumask_any(cpumask);
+	thread = cpu_2_hwthread_id[cpu];
+
+	metag_out32(TBI_TRIG_VEC(TBID_SIGNUM_TR1(thread)),
+		    metag_hwvec_addr(hw));
+
+	return 0;
+}
+#endif
+
+/*
+ *	metag_internal_irq_demux - irq de-multiplexer
+ *	@irq:	the interrupt number
+ *	@desc:	the interrupt description structure for this irq
+ *
+ *	The cpu receives an interrupt on TR1 when an interrupt has
+ *	occurred. It is this function's job to demux this irq and
+ *	figure out exactly which trigger needs servicing.
+ */
+static void metag_internal_irq_demux(unsigned int irq, struct irq_desc *desc)
+{
+	struct metag_internal_irq_priv *priv = irq_desc_get_handler_data(desc);
+	irq_hw_number_t hw;
+	unsigned int irq_no;
+	u32 status;
+
+recalculate:
+	status = metag_in32(HWSTATMETA) & priv->unmasked;
+
+	for (hw = 0; status != 0; status >>= 1, ++hw) {
+		if (status & 0x1) {
+			/*
+			 * Map the hardware IRQ number to a virtual Linux IRQ
+			 * number.
+			 */
+			irq_no = irq_linear_revmap(priv->domain, hw);
+
+			/*
+			 * Only fire off interrupts that are
+			 * registered to be handled by the kernel.
+			 * Other interrupts are probably being
+			 * handled by other Meta hardware threads.
+			 */
+			generic_handle_irq(irq_no);
+
+			/*
+			 * The handler may have re-enabled interrupts
+			 * which could have caused a nested invocation
+			 * of this code and make the copy of the
+			 * status register we are using invalid.
+			 */
+			goto recalculate;
+		}
+	}
+}
+
+/**
+ * internal_irq_map() - Map an internal meta IRQ to a virtual IRQ number.
+ * @hw:		Number of the internal IRQ. Must be in range.
+ *
+ * Returns:	The virtual IRQ number of the Meta internal IRQ specified by
+ *		@hw.
+ */
+int internal_irq_map(unsigned int hw)
+{
+	struct metag_internal_irq_priv *priv = &metag_internal_irq_priv;
+	if (!priv->domain)
+		return -ENODEV;
+	return irq_create_mapping(priv->domain, hw);
+}
+
+/**
+ *	metag_internal_irq_init_cpu - regsister with the Meta cpu
+ *	@cpu:	the CPU to register on
+ *
+ *	Configure @cpu's TR1 irq so that we can demux irqs.
+ */
+static void metag_internal_irq_init_cpu(struct metag_internal_irq_priv *priv,
+					int cpu)
+{
+	unsigned int thread = cpu_2_hwthread_id[cpu];
+	unsigned int signum = TBID_SIGNUM_TR1(thread);
+	int irq = tbisig_map(signum);
+
+	/* Register the multiplexed IRQ handler */
+	irq_set_handler_data(irq, priv);
+	irq_set_chained_handler(irq, metag_internal_irq_demux);
+	irq_set_irq_type(irq, IRQ_TYPE_LEVEL_LOW);
+}
+
+/**
+ * metag_internal_intc_map() - map an internal irq
+ * @d:		irq domain of internal trigger block
+ * @irq:	virtual irq number
+ * @hw:		hardware irq number within internal trigger block
+ *
+ * This sets up a virtual irq for a specified hardware interrupt. The irq chip
+ * and handler is configured.
+ */
+static int metag_internal_intc_map(struct irq_domain *d, unsigned int irq,
+				   irq_hw_number_t hw)
+{
+	/* only register interrupt if it is mapped */
+	if (!metag_hwvec_addr(hw))
+		return -EINVAL;
+
+	irq_set_chip_and_handler(irq, &internal_irq_edge_chip,
+				 handle_edge_irq);
+	return 0;
+}
+
+static const struct irq_domain_ops metag_internal_intc_domain_ops = {
+	.map	= metag_internal_intc_map,
+};
+
+/**
+ *	metag_internal_irq_register - register internal IRQs
+ *
+ *	Register the irq chip and handler function for all internal IRQs
+ */
+int __init init_internal_IRQ(void)
+{
+	struct metag_internal_irq_priv *priv = &metag_internal_irq_priv;
+	unsigned int cpu;
+
+	/* Set up an IRQ domain */
+	priv->domain = irq_domain_add_linear(NULL, 32,
+					     &metag_internal_intc_domain_ops,
+					     priv);
+	if (unlikely(!priv->domain)) {
+		pr_err("meta-internal-intc: cannot add IRQ domain\n");
+		return -ENOMEM;
+	}
+
+	/* Setup TR1 for all cpus. */
+	for_each_possible_cpu(cpu)
+		metag_internal_irq_init_cpu(priv, cpu);
+
+	return 0;
+};

include/linux/irqchip/metag-ext.h

···
+/*
+ * Copyright (C) 2012 Imagination Technologies
+ */
+
+#ifndef _LINUX_IRQCHIP_METAG_EXT_H_
+#define _LINUX_IRQCHIP_METAG_EXT_H_
+
+struct irq_data;
+struct platform_device;
+
+/* called from core irq code at init */
+int init_external_IRQ(void);
+
+/*
+ * called from SoC init_irq() callback to dynamically indicate the lack of
+ * HWMASKEXT registers.
+ */
+void meta_intc_no_mask(void);
+
+/*
+ * These allow SoCs to specialise the interrupt controller from their init_irq
+ * callbacks.
+ */
+
+extern struct irq_chip meta_intc_edge_chip;
+extern struct irq_chip meta_intc_level_chip;
+
+/* this should be called in the mask callback */
+void meta_intc_mask_irq_simple(struct irq_data *data);
+/* this should be called in the unmask callback */
+void meta_intc_unmask_irq_simple(struct irq_data *data);
+
+#endif /* _LINUX_IRQCHIP_METAG_EXT_H_ */

include/linux/irqchip/metag.h

···
+/*
+ * Copyright (C) 2011 Imagination Technologies
+ */
+
+#ifndef _LINUX_IRQCHIP_METAG_H_
+#define _LINUX_IRQCHIP_METAG_H_
+
+#include <linux/errno.h>
+
+#ifdef CONFIG_METAG_PERFCOUNTER_IRQS
+extern int init_internal_IRQ(void);
+extern int internal_irq_map(unsigned int hw);
+#else
+static inline int init_internal_IRQ(void)
+{
+	return 0;
+}
+static inline int internal_irq_map(unsigned int hw)
+{
+	return -EINVAL;
+}
+#endif
+
+#endif /* _LINUX_IRQCHIP_METAG_H_ */