drivers/irqchip: Add STM32 external interrupts support

The STM32 external interrupt controller consists of edge detectors that
generate interrupts requests or wake-up events.

Each line can be independently configured as interrupt or wake-up source,
and triggers either on rising, falling or both edges. Each line can also
be masked independently.

Originally-from: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Signed-off-by: Alexandre TORGUE <alexandre.torgue@st.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: devicetree@vger.kernel.org
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: arnd@arndb.de
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: bruherrera@gmail.com
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: linux-gpio@vger.kernel.org
Cc: Rob Herring <robh+dt@kernel.org>
Cc: lee.jones@linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1474387259-18926-3-git-send-email-alexandre.torgue@st.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

drivers/irqchip/Kconfig

@@ -265,3 +265,7 @@ config EZNPS_GIC
 	select IRQ_DOMAIN
 	help
 	  Support the EZchip NPS400 global interrupt controller
+
+config STM32_EXTI
+	bool
+	select IRQ_DOMAIN

drivers/irqchip/Makefile

@@ -71,3 +71,4 @@ obj-$(CONFIG_MVEBU_ODMI)		+= irq-mvebu-odmi.o
 obj-$(CONFIG_LS_SCFG_MSI)		+= irq-ls-scfg-msi.o
 obj-$(CONFIG_EZNPS_GIC)			+= irq-eznps.o
 obj-$(CONFIG_ARCH_ASPEED)		+= irq-aspeed-vic.o
+obj-$(CONFIG_STM32_EXTI) 		+= irq-stm32-exti.o

drivers/irqchip/irq-stm32-exti.c

@@ -0,0 +1,201 @@
+/*
+ * Copyright (C) Maxime Coquelin 2015
+ * Author:  Maxime Coquelin <mcoquelin.stm32@gmail.com>
+ * License terms:  GNU General Public License (GPL), version 2
+ */
+
+#include <linux/bitops.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/irqchip.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/irqdomain.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+
+#define EXTI_IMR	0x0
+#define EXTI_EMR	0x4
+#define EXTI_RTSR	0x8
+#define EXTI_FTSR	0xc
+#define EXTI_SWIER	0x10
+#define EXTI_PR		0x14
+
+static void stm32_irq_handler(struct irq_desc *desc)
+{
+	struct irq_domain *domain = irq_desc_get_handler_data(desc);
+	struct irq_chip_generic *gc = domain->gc->gc[0];
+	struct irq_chip *chip = irq_desc_get_chip(desc);
+	unsigned long pending;
+	int n;
+
+	chained_irq_enter(chip, desc);
+
+	while ((pending = irq_reg_readl(gc, EXTI_PR))) {
+		for_each_set_bit(n, &pending, BITS_PER_LONG) {
+			generic_handle_irq(irq_find_mapping(domain, n));
+			irq_reg_writel(gc, BIT(n), EXTI_PR);
+		}
+	}
+
+	chained_irq_exit(chip, desc);
+}
+
+static int stm32_irq_set_type(struct irq_data *data, unsigned int type)
+{
+	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(data);
+	int pin = data->hwirq;
+	u32 rtsr, ftsr;
+
+	irq_gc_lock(gc);
+
+	rtsr = irq_reg_readl(gc, EXTI_RTSR);
+	ftsr = irq_reg_readl(gc, EXTI_FTSR);
+
+	switch (type) {
+	case IRQ_TYPE_EDGE_RISING:
+		rtsr |= BIT(pin);
+		ftsr &= ~BIT(pin);
+		break;
+	case IRQ_TYPE_EDGE_FALLING:
+		rtsr &= ~BIT(pin);
+		ftsr |= BIT(pin);
+		break;
+	case IRQ_TYPE_EDGE_BOTH:
+		rtsr |= BIT(pin);
+		ftsr |= BIT(pin);
+		break;
+	default:
+		irq_gc_unlock(gc);
+		return -EINVAL;
+	}
+
+	irq_reg_writel(gc, rtsr, EXTI_RTSR);
+	irq_reg_writel(gc, ftsr, EXTI_FTSR);
+
+	irq_gc_unlock(gc);
+
+	return 0;
+}
+
+static int stm32_irq_set_wake(struct irq_data *data, unsigned int on)
+{
+	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(data);
+	int pin = data->hwirq;
+	u32 emr;
+
+	irq_gc_lock(gc);
+
+	emr = irq_reg_readl(gc, EXTI_EMR);
+	if (on)
+		emr |= BIT(pin);
+	else
+		emr &= ~BIT(pin);
+	irq_reg_writel(gc, emr, EXTI_EMR);
+
+	irq_gc_unlock(gc);
+
+	return 0;
+}
+
+static int stm32_exti_alloc(struct irq_domain *d, unsigned int virq,
+			    unsigned int nr_irqs, void *data)
+{
+	struct irq_chip_generic *gc = d->gc->gc[0];
+	struct irq_fwspec *fwspec = data;
+	irq_hw_number_t hwirq;
+
+	hwirq = fwspec->param[0];
+
+	irq_map_generic_chip(d, virq, hwirq);
+	irq_domain_set_info(d, virq, hwirq, &gc->chip_types->chip, gc,
+			    handle_simple_irq, NULL, NULL);
+
+	return 0;
+}
+
+static void stm32_exti_free(struct irq_domain *d, unsigned int virq,
+			    unsigned int nr_irqs)
+{
+	struct irq_data *data = irq_domain_get_irq_data(d, virq);
+
+	irq_domain_reset_irq_data(data);
+}
+
+struct irq_domain_ops irq_exti_domain_ops = {
+	.map	= irq_map_generic_chip,
+	.xlate	= irq_domain_xlate_onetwocell,
+	.alloc  = stm32_exti_alloc,
+	.free	= stm32_exti_free,
+};
+
+static int __init stm32_exti_init(struct device_node *node,
+				  struct device_node *parent)
+{
+	unsigned int clr = IRQ_NOREQUEST | IRQ_NOPROBE | IRQ_NOAUTOEN;
+	int nr_irqs, nr_exti, ret, i;
+	struct irq_chip_generic *gc;
+	struct irq_domain *domain;
+	void *base;
+
+	base = of_iomap(node, 0);
+	if (!base) {
+		pr_err("%s: Unable to map registers\n", node->full_name);
+		return -ENOMEM;
+	}
+
+	/* Determine number of irqs supported */
+	writel_relaxed(~0UL, base + EXTI_RTSR);
+	nr_exti = fls(readl_relaxed(base + EXTI_RTSR));
+	writel_relaxed(0, base + EXTI_RTSR);
+
+	pr_info("%s: %d External IRQs detected\n", node->full_name, nr_exti);
+
+	domain = irq_domain_add_linear(node, nr_exti,
+				       &irq_exti_domain_ops, NULL);
+	if (!domain) {
+		pr_err("%s: Could not register interrupt domain.\n",
+				node->name);
+		ret = -ENOMEM;
+		goto out_unmap;
+	}
+
+	ret = irq_alloc_domain_generic_chips(domain, nr_exti, 1, "exti",
+					     handle_edge_irq, clr, 0, 0);
+	if (ret) {
+		pr_err("%s: Could not allocate generic interrupt chip.\n",
+			node->full_name);
+		goto out_free_domain;
+	}
+
+	gc = domain->gc->gc[0];
+	gc->reg_base                         = base;
+	gc->chip_types->type               = IRQ_TYPE_EDGE_BOTH;
+	gc->chip_types->chip.name          = gc->chip_types[0].chip.name;
+	gc->chip_types->chip.irq_ack       = irq_gc_ack_set_bit;
+	gc->chip_types->chip.irq_mask      = irq_gc_mask_clr_bit;
+	gc->chip_types->chip.irq_unmask    = irq_gc_mask_set_bit;
+	gc->chip_types->chip.irq_set_type  = stm32_irq_set_type;
+	gc->chip_types->chip.irq_set_wake  = stm32_irq_set_wake;
+	gc->chip_types->regs.ack           = EXTI_PR;
+	gc->chip_types->regs.mask          = EXTI_IMR;
+	gc->chip_types->handler            = handle_edge_irq;
+
+	nr_irqs = of_irq_count(node);
+	for (i = 0; i < nr_irqs; i++) {
+		unsigned int irq = irq_of_parse_and_map(node, i);
+
+		irq_set_handler_data(irq, domain);
+		irq_set_chained_handler(irq, stm32_irq_handler);
+	}
+
+	return 0;
+
+out_free_domain:
+	irq_domain_remove(domain);
+out_unmap:
+	iounmap(base);
+	return ret;
+}
+
+IRQCHIP_DECLARE(stm32_exti, "st,stm32-exti", stm32_exti_init);