[PATCH v6 2/9] irqchip: add Amlogic Meson GPIO irqchip driver

[Heiner Kallweit <hkallweit1@gmail.com>]

Add a driver supporting the GPIO interrupt controller on certain
Amlogic meson SoC's.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
v5:
- changed Kconfig entry based on Neil's suggestion
- added authors
- extended explanation why 2 * n hwirqs are used
v6:
- change DT property parent-interrupts to interrupts
---
 drivers/irqchip/Kconfig          |   5 +
 drivers/irqchip/Makefile         |   1 +
 drivers/irqchip/irq-meson-gpio.c | 295 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 302 insertions(+)
 create mode 100644 drivers/irqchip/irq-meson-gpio.c

diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index 478f8ace..bdc86e14 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -301,3 +301,8 @@ config QCOM_IRQ_COMBINER
 	help
 	  Say yes here to add support for the IRQ combiner devices embedded
 	  in Qualcomm Technologies chips.
+
+config MESON_GPIO_INTC
+	bool
+	depends on ARCH_MESON
+	default y
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index b64c59b8..1be482bd 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -76,3 +76,4 @@ obj-$(CONFIG_EZNPS_GIC)			+= irq-eznps.o
 obj-$(CONFIG_ARCH_ASPEED)		+= irq-aspeed-vic.o
 obj-$(CONFIG_STM32_EXTI) 		+= irq-stm32-exti.o
 obj-$(CONFIG_QCOM_IRQ_COMBINER)		+= qcom-irq-combiner.o
+obj-$(CONFIG_MESON_GPIO_INTC)		+= irq-meson-gpio.o
diff --git a/drivers/irqchip/irq-meson-gpio.c b/drivers/irqchip/irq-meson-gpio.c
new file mode 100644
index 00000000..b09228ea
--- /dev/null
+++ b/drivers/irqchip/irq-meson-gpio.c
@@ -0,0 +1,295 @@
+/*
+ * Amlogic Meson GPIO IRQ chip driver
+ *
+ * Copyright (c) 2015 Endless Mobile, Inc.
+ * Author: Carlo Caione <carlo@endlessm.com>
+ * Copyright (c) 2016 BayLibre, SAS.
+ * Author: Jerome Brunet <jbrunet@baylibre.com>
+ * Copyright (c) 2017 Heiner Kallweit <hkallweit1@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2.
+ */
+
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/irqchip.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
+#include <linux/regmap.h>
+
+#define REG_EDGE_POL		0x00
+#define REG_PIN_03_SEL		0x04
+#define REG_PIN_47_SEL		0x08
+#define REG_FILTER_SEL		0x0c
+
+#define REG_EDGE_POL_MASK(x)	(BIT(x) | BIT(16 + (x)))
+#define REG_EDGE_POL_EDGE(x)	BIT(x)
+#define REG_EDGE_POL_LOW(x)	BIT(16 + (x))
+
+#define MAX_PARENT_IRQ_NUM	8
+
+/* maximum number of GPIO IRQs on supported platforms */
+#define MAX_NUM_GPIO_IRQ	133
+
+/*
+ * In case of IRQ_TYPE_EDGE_BOTH we need two parent interrupts, one for each
+ * edge. That's due to HW constraints.
+ * We use format 2 * GPIO_HWIRQ +(0|1) for the hwirq, so we can have one
+ * GPIO_HWIRQ twice and derive the GPIO_HWIRQ from hwirq by shifting hwirq
+ * one bit to the right.
+ */
+#define NUM_GPIO_HWIRQ		(2 * MAX_NUM_GPIO_IRQ)
+
+struct meson_irq_slot {
+	unsigned int irq;
+	unsigned int owner;
+};
+
+struct meson_data {
+	struct regmap *regmap;
+	struct meson_irq_slot slots[MAX_PARENT_IRQ_NUM];
+	unsigned int num_slots;
+	struct mutex lock;
+};
+
+static int meson_alloc_irq_slot(struct meson_data *md, unsigned int virq)
+{
+	int i, slot = -ENOSPC;
+
+	mutex_lock(&md->lock);
+
+	for (i = 0; i < md->num_slots && slot < 0; i++)
+		if (!md->slots[i].owner) {
+			md->slots[i].owner = virq;
+			slot = i;
+		}
+
+	mutex_unlock(&md->lock);
+
+	return slot;
+}
+
+static void meson_free_irq_slot(struct meson_data *md, unsigned int virq)
+{
+	int i;
+
+	mutex_lock(&md->lock);
+
+	for (i = 0; i < md->num_slots; i++)
+		if (md->slots[i].owner == virq) {
+			md->slots[i].owner = 0;
+			break;
+		}
+
+	mutex_unlock(&md->lock);
+}
+
+static int meson_find_irq_slot(struct meson_data *md, unsigned int virq)
+{
+	int i, slot = -EINVAL;
+
+	mutex_lock(&md->lock);
+
+	for (i = 0; i < md->num_slots && slot < 0; i++)
+		if (md->slots[i].owner == virq)
+			slot = i;
+
+	mutex_unlock(&md->lock);
+
+	return slot;
+}
+
+static void meson_set_hwirq(struct meson_data *md, int idx, unsigned int hwirq)
+{
+	int reg = idx > 3 ? REG_PIN_47_SEL : REG_PIN_03_SEL;
+	int shift = 8 * (idx % 4);
+
+	regmap_update_bits(md->regmap, reg, 0xff << shift,
+			   hwirq << shift);
+}
+
+static void meson_irq_set_hwirq(struct irq_data *data, unsigned int hwirq)
+{
+	struct meson_data *md = data->domain->host_data;
+	int slot = meson_find_irq_slot(md, data->irq);
+
+	if (slot >= 0)
+		meson_set_hwirq(md, slot, hwirq);
+}
+
+static int meson_irq_set_type(struct irq_data *data, unsigned int type)
+{
+	struct meson_data *md = data->domain->host_data;
+	int slot;
+	unsigned int val = 0;
+
+	if (type == IRQ_TYPE_EDGE_BOTH)
+		return -EINVAL;
+
+	slot = meson_find_irq_slot(md, data->irq);
+	if (slot < 0)
+		return slot;
+
+	if (type & IRQ_TYPE_EDGE_BOTH)
+		val |= REG_EDGE_POL_EDGE(slot);
+
+	if (type & (IRQ_TYPE_LEVEL_LOW | IRQ_TYPE_EDGE_FALLING))
+		val |= REG_EDGE_POL_LOW(slot);
+
+	regmap_update_bits(md->regmap, REG_EDGE_POL,
+			   REG_EDGE_POL_MASK(slot), val);
+
+	if (type & IRQ_TYPE_EDGE_BOTH)
+		val = IRQ_TYPE_EDGE_RISING;
+	else
+		val = IRQ_TYPE_LEVEL_HIGH;
+
+	return irq_chip_set_type_parent(data, val);
+}
+
+static unsigned int meson_irq_startup(struct irq_data *data)
+{
+	irq_chip_unmask_parent(data);
+	/*
+	 * An extra bit was added to allow having the same gpio hwirq twice
+	 * for handling IRQ_TYPE_EDGE_BOTH. Remove this bit to get the
+	 * gpio hwirq.
+	 */
+	meson_irq_set_hwirq(data, data->hwirq >> 1);
+
+	return 0;
+}
+
+static void meson_irq_shutdown(struct irq_data *data)
+{
+	meson_irq_set_hwirq(data, 0xff);
+	irq_chip_mask_parent(data);
+}
+
+static struct irq_chip meson_irq_chip = {
+	.name = "meson_gpio_intc",
+	.irq_set_type = meson_irq_set_type,
+	.irq_eoi = irq_chip_eoi_parent,
+	.irq_mask = irq_chip_mask_parent,
+	.irq_unmask = irq_chip_unmask_parent,
+	.irq_startup = meson_irq_startup,
+	.irq_shutdown = meson_irq_shutdown,
+	.irq_set_affinity = irq_chip_set_affinity_parent,
+};
+
+static int meson_irq_alloc(struct irq_domain *d, unsigned int virq,
+			   unsigned int nr_irqs, void *data)
+{
+	struct irq_fwspec parent_fwspec, *fwspec = data;
+	struct meson_data *md = d->host_data;
+	irq_hw_number_t hwirq;
+	int ret, slot;
+
+	slot = meson_alloc_irq_slot(md, virq);
+	if (slot < 0)
+		return slot;
+
+	hwirq = fwspec->param[0];
+	irq_domain_set_hwirq_and_chip(d, virq, hwirq, &meson_irq_chip, NULL);
+
+	parent_fwspec.fwnode = d->parent->fwnode;
+	parent_fwspec.param_count = 3;
+	parent_fwspec.param[0] = 0; /* SPI */
+	parent_fwspec.param[1] = md->slots[slot].irq;
+	parent_fwspec.param[2] = IRQ_TYPE_NONE;
+
+	ret = irq_domain_alloc_irqs_parent(d, virq, nr_irqs, &parent_fwspec);
+	if (ret)
+		meson_free_irq_slot(md, virq);
+
+	return ret;
+}
+
+static void meson_irq_free(struct irq_domain *d, unsigned int virq,
+			   unsigned int nr_irqs)
+{
+	struct meson_data *md = d->host_data;
+
+	irq_domain_free_irqs_common(d, virq, nr_irqs);
+	meson_free_irq_slot(md, virq);
+}
+
+static const struct irq_domain_ops meson_irq_ops = {
+	.alloc = meson_irq_alloc,
+	.free = meson_irq_free,
+	.xlate = irq_domain_xlate_twocell,
+};
+
+static int meson_get_irqs(struct meson_data *md, struct device_node *node)
+{
+	int ret, i;
+	u32 irq;
+
+	for (i = 0; i < MAX_PARENT_IRQ_NUM; i++) {
+		ret = of_property_read_u32_index(node, "interrupts", i, &irq);
+		if (ret)
+			break;
+		md->slots[i].irq = irq;
+	}
+
+	md->num_slots = i;
+
+	return i ? 0 : -EINVAL;
+}
+
+static const struct regmap_config meson_regmap_config = {
+	.reg_bits       = 32,
+	.reg_stride     = 4,
+	.val_bits       = 32,
+	.max_register	= REG_FILTER_SEL,
+};
+
+static int __init meson_gpio_irq_init(struct device_node *node,
+				      struct device_node *parent)
+{
+	struct irq_domain *meson_irq_domain, *parent_domain;
+	struct meson_data *md;
+	void __iomem *io_base;
+	int ret;
+
+	md = kzalloc(sizeof(*md), GFP_KERNEL);
+	if (!md)
+		return -ENOMEM;
+
+	mutex_init(&md->lock);
+
+	io_base = of_iomap(node, 0);
+	if (!io_base)
+		return -EINVAL;
+
+	md->regmap = regmap_init_mmio(NULL, io_base, &meson_regmap_config);
+	if (IS_ERR(md->regmap))
+		return PTR_ERR(md->regmap);
+
+	/* initialize to IRQ_TYPE_LEVEL_HIGH */
+	regmap_write(md->regmap, REG_EDGE_POL, 0);
+	/* disable all GPIO interrupt sources */
+	regmap_write(md->regmap, REG_PIN_03_SEL, 0xffffffff);
+	regmap_write(md->regmap, REG_PIN_47_SEL, 0xffffffff);
+	/* disable filtering */
+	regmap_write(md->regmap, REG_FILTER_SEL, 0);
+
+	ret = meson_get_irqs(md, node);
+	if (ret)
+		return ret;
+
+	parent_domain = irq_find_host(parent);
+	if (!parent_domain)
+		return -ENXIO;
+
+	meson_irq_domain = irq_domain_add_hierarchy(parent_domain, 0,
+						    NUM_GPIO_HWIRQ, node,
+						    &meson_irq_ops, md);
+	return meson_irq_domain ? 0 : -EINVAL;
+}
+
+IRQCHIP_DECLARE(meson_gpio_irq, "amlogic,meson-gpio-intc", meson_gpio_irq_init);
-- 
2.13.0