[PATCH 08/10] irqchip: add LPC32xx interrupt controller driver

[Vladimir Zapolskiy <vz-ChpfBGZJDbMAvxtiuMwx3w@public.gmane.org>]

The change adds improved support of NXP LPC32xx MIC, SIC1 and SIC2
interrupt controllers.

This is a list of new features in comparison to the legacy driver:
* irq types are taken from device tree settings, no more need to
  hardcode them,
* old driver is based on irq_domain_add_legacy, which causes problems
  with handling MIC hardware interrupt 0 produced by SIC1,
* there is one driver for MIC, SIC1 and SIC2, no more need to handle
  them separately, e.g. have two separate handlers for SIC1 and SIC2,
* the driver does not have any dependencies on hardcoded register
  offsets,
* the driver is much simpler for comprehension and more maintainable,
* SPARSE_IRQS option is supported.

The change disables compilation of a legacy driver found at
arch/arm/mach-lpc32xx/irq.c, the file will be removed in a separate
commit.

Signed-off-by: Vladimir Zapolskiy <vz-ChpfBGZJDbMAvxtiuMwx3w@public.gmane.org>
---
 arch/arm/Kconfig                |   2 +
 arch/arm/mach-lpc32xx/Makefile  |   2 +-
 arch/arm/mach-lpc32xx/phy3250.c |   1 -
 drivers/irqchip/Makefile        |   1 +
 drivers/irqchip/irq-lpc32xx.c   | 227 ++++++++++++++++++++++++++++++++++++++++
 5 files changed, 231 insertions(+), 2 deletions(-)
 create mode 100644 drivers/irqchip/irq-lpc32xx.c

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 5cc11f1..1f2c03f 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -597,6 +597,8 @@ config ARCH_LPC32XX
 	select CPU_ARM926T
 	select GENERIC_CLOCKEVENTS
 	select HAVE_IDE
+	select MULTI_IRQ_HANDLER
+	select SPARSE_IRQ
 	select USE_OF
 	help
 	  Support for the NXP LPC32XX family of processors
diff --git a/arch/arm/mach-lpc32xx/Makefile b/arch/arm/mach-lpc32xx/Makefile
index b1023c0..2a28f645 100644
--- a/arch/arm/mach-lpc32xx/Makefile
+++ b/arch/arm/mach-lpc32xx/Makefile
@@ -2,6 +2,6 @@
 # Makefile for the linux kernel.
 #
 
-obj-y	:= irq.o common.o serial.o
+obj-y	:= common.o serial.o
 obj-y	+= pm.o suspend.o wakeup.o
 obj-y	+= phy3250.o
diff --git a/arch/arm/mach-lpc32xx/phy3250.c b/arch/arm/mach-lpc32xx/phy3250.c
index 60f3392..92e8574 100644
--- a/arch/arm/mach-lpc32xx/phy3250.c
+++ b/arch/arm/mach-lpc32xx/phy3250.c
@@ -259,7 +259,6 @@ static const char *const lpc32xx_dt_compat[] __initconst = {
 DT_MACHINE_START(LPC32XX_DT, "LPC32XX SoC (Flattened Device Tree)")
 	.atag_offset	= 0x100,
 	.map_io		= lpc32xx_map_io,
-	.init_irq	= lpc32xx_init_irq,
 	.init_machine	= lpc3250_machine_init,
 	.dt_compat	= lpc32xx_dt_compat,
 	.restart	= lpc23xx_restart,
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index 177f78f..21008a6 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -4,6 +4,7 @@ obj-$(CONFIG_ARCH_BCM2835)		+= irq-bcm2835.o
 obj-$(CONFIG_ARCH_BCM2835)		+= irq-bcm2836.o
 obj-$(CONFIG_ARCH_EXYNOS)		+= exynos-combiner.o
 obj-$(CONFIG_ARCH_HIP04)		+= irq-hip04.o
+obj-$(CONFIG_ARCH_LPC32XX)		+= irq-lpc32xx.o
 obj-$(CONFIG_ARCH_MMP)			+= irq-mmp.o
 obj-$(CONFIG_ARCH_MVEBU)		+= irq-armada-370-xp.o
 obj-$(CONFIG_IRQ_MXS)			+= irq-mxs.o
diff --git a/drivers/irqchip/irq-lpc32xx.c b/drivers/irqchip/irq-lpc32xx.c
new file mode 100644
index 0000000..fcf281b
--- /dev/null
+++ b/drivers/irqchip/irq-lpc32xx.c
@@ -0,0 +1,227 @@
+/*
+ * Copyright 2015 Vladimir Zapolskiy <vz-ChpfBGZJDbMAvxtiuMwx3w@public.gmane.org>
+ *
+ * The code contained herein is licensed under the GNU General Public
+ * License. You may obtain a copy of the GNU General Public License
+ * Version 2 or later at the following locations:
+ *
+ * http://www.opensource.org/licenses/gpl-license.html
+ * http://www.gnu.org/copyleft/gpl.html
+ */
+
+#define pr_fmt(fmt) "%s: " fmt, __func__
+
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/irqchip.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/of_platform.h>
+#include <linux/slab.h>
+#include <asm/exception.h>
+
+#define LPC32XX_INTC_MASK		0x00
+#define LPC32XX_INTC_RAW		0x04
+#define LPC32XX_INTC_STAT		0x08
+#define LPC32XX_INTC_POL		0x0C
+#define LPC32XX_INTC_TYPE		0x10
+#define LPC32XX_INTC_FIQ		0x14
+
+#define IRQS_PER_CONTROLLER		32
+
+struct lpc32xx_irq_chip {
+	void __iomem *base;
+	struct irq_domain *domain;
+	struct irq_chip chip;
+};
+
+static struct lpc32xx_irq_chip *lpc32xx_mic_data;
+
+static inline u32 lpc32xx_ic_read(struct irq_domain *id, u32 reg)
+{
+	struct lpc32xx_irq_chip *ic = (struct lpc32xx_irq_chip *)id->host_data;
+
+	return readl(ic->base + reg);
+}
+
+static inline void lpc32xx_ic_write(struct irq_domain *id, u32 reg, u32 val)
+{
+	struct lpc32xx_irq_chip *ic = (struct lpc32xx_irq_chip *)id->host_data;
+
+	writel(val, ic->base + reg);
+}
+
+static void lpc32xx_irq_mask(struct irq_data *d)
+{
+	u32 val, mask = BIT(d->hwirq);
+
+	val = lpc32xx_ic_read(d->domain, LPC32XX_INTC_MASK) & ~mask;
+	lpc32xx_ic_write(d->domain, LPC32XX_INTC_MASK, val);
+}
+
+static void lpc32xx_irq_unmask(struct irq_data *d)
+{
+	u32 val, mask = BIT(d->hwirq);
+
+	val = lpc32xx_ic_read(d->domain, LPC32XX_INTC_MASK) | mask;
+	lpc32xx_ic_write(d->domain, LPC32XX_INTC_MASK, val);
+}
+
+static void lpc32xx_irq_ack(struct irq_data *d)
+{
+	u32 mask = BIT(d->hwirq);
+
+	lpc32xx_ic_write(d->domain, LPC32XX_INTC_RAW, mask);
+}
+
+static int lpc32xx_irq_set_type(struct irq_data *d, unsigned int type)
+{
+	struct irq_domain *domain = d->domain;
+	u32 val, mask = BIT(d->hwirq);
+	bool high, edge;
+
+	switch (type) {
+	case IRQ_TYPE_EDGE_RISING:
+		edge = true;
+		high = true;
+		break;
+	case IRQ_TYPE_EDGE_FALLING:
+		edge = true;
+		high = false;
+		break;
+	case IRQ_TYPE_LEVEL_HIGH:
+		edge = false;
+		high = true;
+		break;
+	case IRQ_TYPE_LEVEL_LOW:
+		edge = false;
+		high = false;
+		break;
+	default:
+		pr_info("unsupported irq type %d\n", type);
+		return -EINVAL;
+	}
+
+	irqd_set_trigger_type(d, type);
+
+	val = lpc32xx_ic_read(domain, LPC32XX_INTC_POL);
+	if (high)
+		val |= mask;
+	else
+		val &= ~mask;
+	lpc32xx_ic_write(domain, LPC32XX_INTC_POL, val);
+
+	val = lpc32xx_ic_read(domain, LPC32XX_INTC_TYPE);
+	if (edge) {
+		val |= mask;
+		irq_set_handler_locked(d, handle_edge_irq);
+	} else {
+		val &= ~mask;
+		irq_set_handler_locked(d, handle_level_irq);
+	}
+	lpc32xx_ic_write(domain, LPC32XX_INTC_TYPE, val);
+
+	return 0;
+}
+
+static void __exception_irq_entry lpc32xx_handle_irq(struct pt_regs *regs)
+{
+	u32 hwirq;
+
+	do {
+		hwirq = lpc32xx_ic_read(lpc32xx_mic_data->domain,
+					LPC32XX_INTC_STAT);
+		if (hwirq)
+			handle_domain_irq(lpc32xx_mic_data->domain,
+					  ffs(hwirq) - 1, regs);
+	} while (hwirq);
+}
+
+static void lpc32xx_sic_handler(struct irq_desc *desc)
+{
+	struct lpc32xx_irq_chip *ic = irq_desc_get_handler_data(desc);
+	struct irq_domain *domain = ic->domain;
+	u32 hwirq;
+
+	do {
+		hwirq = lpc32xx_ic_read(domain, LPC32XX_INTC_STAT);
+		if (hwirq)
+			generic_handle_irq(irq_find_mapping(domain,
+							    ffs(hwirq) - 1));
+	} while (hwirq);
+}
+
+static int lpc32xx_irq_domain_map(struct irq_domain *id, unsigned int virq,
+				  irq_hw_number_t hw)
+{
+	struct lpc32xx_irq_chip *ic = (struct lpc32xx_irq_chip *)id->host_data;
+
+	irq_set_chip_and_handler(virq, &ic->chip, handle_level_irq);
+	irq_set_status_flags(virq, IRQ_LEVEL);
+	irq_set_noprobe(virq);
+
+	return 0;
+}
+
+static void lpc32xx_irq_domain_unmap(struct irq_domain *id, unsigned int virq)
+{
+	irq_set_chip_and_handler(virq, NULL, NULL);
+}
+
+static const struct irq_domain_ops lpc32xx_irq_domain_ops = {
+	.map    = lpc32xx_irq_domain_map,
+	.unmap	= lpc32xx_irq_domain_unmap,
+	.xlate  = irq_domain_xlate_twocell,
+};
+
+static int __init lpc32xx_of_ic_init(struct device_node *node,
+				     struct device_node *parent)
+{
+	int parent_irq, i;
+	struct lpc32xx_irq_chip *irqc;
+
+	irqc = kzalloc(sizeof(*irqc), GFP_KERNEL);
+	if (!irqc)
+		return -ENOMEM;
+
+	irqc->chip.irq_ack = lpc32xx_irq_ack;
+	irqc->chip.irq_mask = lpc32xx_irq_mask;
+	irqc->chip.irq_unmask = lpc32xx_irq_unmask;
+	irqc->chip.irq_set_type = lpc32xx_irq_set_type;
+	irqc->chip.name = of_get_property(node, "interrupt-controller-name",
+					  NULL);
+
+	irqc->base = of_iomap(node, 0);
+	if (!irqc->base) {
+		pr_err("%s: unable to map registers\n", node->full_name);
+		return -EINVAL;
+	}
+
+	irqc->domain = irq_domain_add_linear(node, IRQS_PER_CONTROLLER,
+					     &lpc32xx_irq_domain_ops, irqc);
+	if (!irqc->domain) {
+		pr_err("unable to add irq domain\n");
+		iounmap(irqc->base);
+		return -ENODEV;
+	}
+
+	for (i = 0; i < of_irq_count(node); i++) {
+		parent_irq = irq_of_parse_and_map(node, i);
+		if (parent_irq)
+			irq_set_chained_handler_and_data(parent_irq,
+						 lpc32xx_sic_handler, irqc);
+	}
+
+	if (of_device_is_compatible(node, "nxp,lpc3220-mic")) {
+		lpc32xx_mic_data = irqc;
+		set_handle_irq(lpc32xx_handle_irq);
+	}
+
+	lpc32xx_ic_write(irqc->domain, LPC32XX_INTC_MASK, 0x00);
+	lpc32xx_ic_write(irqc->domain, LPC32XX_INTC_POL, 0x00);
+	lpc32xx_ic_write(irqc->domain, LPC32XX_INTC_TYPE, 0x00);
+
+	return 0;
+}
+IRQCHIP_DECLARE(nxp_lpc32xx_mic, "nxp,lpc3220-mic", lpc32xx_of_ic_init);
+IRQCHIP_DECLARE(nxp_lpc32xx_sic, "nxp,lpc3220-sic", lpc32xx_of_ic_init);
-- 
2.1.4

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