irqchip: Add LPC32xx interrupt controller driver

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 maintenance,
* SPARSE_IRQS option is supported.

Legacy LPC32xx interrupt controller driver was broken since commit
76ba59f ("genirq: Add irq_domain-aware core IRQ handler"), which
requires a private interrupt handler, otherwise any SIC1 generated
interrupt (mapped to MIC hwirq 0) breaks the kernel with the message
"unexpected IRQ trap at vector 00".

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.

Fixes: 76ba59f ("genirq: Add irq_domain-aware core IRQ handler")
Tested-by: Sylvain Lemieux <slemieux.tyco@gmail.com>
Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

arch/arm/Kconfig

@@ -531,6 +531,8 @@ config ARCH_LPC32XX
 	select COMMON_CLK
 	select CPU_ARM926T
 	select GENERIC_CLOCKEVENTS
+	select MULTI_IRQ_HANDLER
+	select SPARSE_IRQ
 	select USE_OF
 	help
 	  Support for the NXP LPC32XX family of processors

arch/arm/mach-lpc32xx/phy3250.c

@@ -206,7 +206,6 @@ 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,
 MACHINE_END

drivers/irqchip/Makefile

@@ -7,6 +7,7 @@ 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-$(CONFIG_IRQ_MXS)			+= irq-mxs.o
 obj-$(CONFIG_ARCH_TEGRA)		+= irq-tegra.o

drivers/irqchip/irq-lpc32xx.c

@@ -0,0 +1,238 @@
+/*
+ * Copyright 2015-2016 Vladimir Zapolskiy <vz@mleia.com>
+ *
+ * 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/irqchip.h>
+#include <linux/irqchip/chained_irq.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 NR_LPC32XX_IC_IRQS		32
+
+struct lpc32xx_irq_chip {
+	void __iomem *base;
+	struct irq_domain *domain;
+	struct irq_chip chip;
+};
+
+static struct lpc32xx_irq_chip *lpc32xx_mic_irqc;
+
+static inline u32 lpc32xx_ic_read(struct lpc32xx_irq_chip *ic, u32 reg)
+{
+	return readl_relaxed(ic->base + reg);
+}
+
+static inline void lpc32xx_ic_write(struct lpc32xx_irq_chip *ic,
+				    u32 reg, u32 val)
+{
+	writel_relaxed(val, ic->base + reg);
+}
+
+static void lpc32xx_irq_mask(struct irq_data *d)
+{
+	struct lpc32xx_irq_chip *ic = irq_data_get_irq_chip_data(d);
+	u32 val, mask = BIT(d->hwirq);
+
+	val = lpc32xx_ic_read(ic, LPC32XX_INTC_MASK) & ~mask;
+	lpc32xx_ic_write(ic, LPC32XX_INTC_MASK, val);
+}
+
+static void lpc32xx_irq_unmask(struct irq_data *d)
+{
+	struct lpc32xx_irq_chip *ic = irq_data_get_irq_chip_data(d);
+	u32 val, mask = BIT(d->hwirq);
+
+	val = lpc32xx_ic_read(ic, LPC32XX_INTC_MASK) | mask;
+	lpc32xx_ic_write(ic, LPC32XX_INTC_MASK, val);
+}
+
+static void lpc32xx_irq_ack(struct irq_data *d)
+{
+	struct lpc32xx_irq_chip *ic = irq_data_get_irq_chip_data(d);
+	u32 mask = BIT(d->hwirq);
+
+	lpc32xx_ic_write(ic, LPC32XX_INTC_RAW, mask);
+}
+
+static int lpc32xx_irq_set_type(struct irq_data *d, unsigned int type)
+{
+	struct lpc32xx_irq_chip *ic = irq_data_get_irq_chip_data(d);
+	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(ic, LPC32XX_INTC_POL);
+	if (high)
+		val |= mask;
+	else
+		val &= ~mask;
+	lpc32xx_ic_write(ic, LPC32XX_INTC_POL, val);
+
+	val = lpc32xx_ic_read(ic, 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(ic, LPC32XX_INTC_TYPE, val);
+
+	return 0;
+}
+
+static void __exception_irq_entry lpc32xx_handle_irq(struct pt_regs *regs)
+{
+	struct lpc32xx_irq_chip *ic = lpc32xx_mic_irqc;
+	u32 hwirq = lpc32xx_ic_read(ic, LPC32XX_INTC_STAT), irq;
+
+	while (hwirq) {
+		irq = __ffs(hwirq);
+		hwirq &= ~BIT(irq);
+		handle_domain_irq(lpc32xx_mic_irqc->domain, irq, regs);
+	}
+}
+
+static void lpc32xx_sic_handler(struct irq_desc *desc)
+{
+	struct lpc32xx_irq_chip *ic = irq_desc_get_handler_data(desc);
+	struct irq_chip *chip = irq_desc_get_chip(desc);
+	u32 hwirq = lpc32xx_ic_read(ic, LPC32XX_INTC_STAT), irq;
+
+	chained_irq_enter(chip, desc);
+
+	while (hwirq) {
+		irq = __ffs(hwirq);
+		hwirq &= ~BIT(irq);
+		generic_handle_irq(irq_find_mapping(ic->domain, irq));
+	}
+
+	chained_irq_exit(chip, desc);
+}
+
+static int lpc32xx_irq_domain_map(struct irq_domain *id, unsigned int virq,
+				  irq_hw_number_t hw)
+{
+	struct lpc32xx_irq_chip *ic = id->host_data;
+
+	irq_set_chip_data(virq, ic);
+	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)
+{
+	struct lpc32xx_irq_chip *irqc;
+	bool is_mic = of_device_is_compatible(node, "nxp,lpc3220-mic");
+	const __be32 *reg = of_get_property(node, "reg", NULL);
+	u32 parent_irq, i, addr = reg ? be32_to_cpu(*reg) : 0;
+
+	irqc = kzalloc(sizeof(*irqc), GFP_KERNEL);
+	if (!irqc)
+		return -ENOMEM;
+
+	irqc->base = of_iomap(node, 0);
+	if (!irqc->base) {
+		pr_err("%s: unable to map registers\n", node->full_name);
+		kfree(irqc);
+		return -EINVAL;
+	}
+
+	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;
+	if (is_mic)
+		irqc->chip.name = kasprintf(GFP_KERNEL, "%08x.mic", addr);
+	else
+		irqc->chip.name = kasprintf(GFP_KERNEL, "%08x.sic", addr);
+
+	irqc->domain = irq_domain_add_linear(node, NR_LPC32XX_IC_IRQS,
+					     &lpc32xx_irq_domain_ops, irqc);
+	if (!irqc->domain) {
+		pr_err("unable to add irq domain\n");
+		iounmap(irqc->base);
+		kfree(irqc->chip.name);
+		kfree(irqc);
+		return -ENODEV;
+	}
+
+	if (is_mic) {
+		lpc32xx_mic_irqc = irqc;
+		set_handle_irq(lpc32xx_handle_irq);
+	} else {
+		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);
+		}
+	}
+
+	lpc32xx_ic_write(irqc, LPC32XX_INTC_MASK, 0x00);
+	lpc32xx_ic_write(irqc, LPC32XX_INTC_POL,  0x00);
+	lpc32xx_ic_write(irqc, 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);