gpio: Add support for hierarchical IRQ domains

Hierarchical IRQ domains can be used to stack different IRQ
controllers on top of each other.

Bring hierarchical IRQ domains into the GPIOLIB core with the
following basic idea:

Drivers that need their interrupts handled hierarchically
specify a callback to translate the child hardware IRQ and
IRQ type for each GPIO offset to a parent hardware IRQ and
parent hardware IRQ type.

Users have to pass the callback, fwnode, and parent irqdomain
before calling gpiochip_irqchip_add().

We use the new method of just filling in the struct
gpio_irq_chip before adding the gpiochip for all hierarchical
irqchips of this type.

The code path for device tree is pretty straight-forward,
while the code path for old boardfiles or anything else will
be more convoluted requireing upfront allocation of the
interrupts when adding the chip.

One specific use-case where this can be useful is if a power
management controller has top-level controls for wakeup
interrupts. In such cases, the power management controller can
be a parent to other interrupt controllers and program
additional registers when an IRQ has its wake capability
enabled or disabled.

The hierarchical irqchip helper code will only be available
when IRQ_DOMAIN_HIERARCHY is selected to GPIO chips using
this should select or depend on that symbol. When using
hierarchical IRQs, the parent interrupt controller must
also be hierarchical all the way up to the top interrupt
controller wireing directly into the CPU, so on systems
that do not have this we can get rid of all the extra
code for supporting hierarchical irqs.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Lina Iyer <ilina@codeaurora.org>
Cc: Jon Hunter <jonathanh@nvidia.com>
Cc: Sowjanya Komatineni <skomatineni@nvidia.com>
Cc: Bitan Biswas <bbiswas@nvidia.com>
Cc: linux-tegra@vger.kernel.org
Cc: David Daney <david.daney@cavium.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Brian Masney <masneyb@onstation.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Brian Masney <masneyb@onstation.org>
Co-developed-by: Brian Masney <masneyb@onstation.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20190808123242.5359-1-linus.walleij@linaro.org

1 files changed, 308 insertions, 12 deletions

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 537a37a89891..5277b8f1ff7c 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1720,6 +1720,273 @@ void gpiochip_set_nested_irqchip(struct gpio_chip *gpiochip,
 }
 EXPORT_SYMBOL_GPL(gpiochip_set_nested_irqchip);
 
+#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
+
+/**
+ * gpiochip_set_hierarchical_irqchip() - connects a hierarchical irqchip
+ * to a gpiochip
+ * @gc: the gpiochip to set the irqchip hierarchical handler to
+ * @irqchip: the irqchip to handle this level of the hierarchy, the interrupt
+ * will then percolate up to the parent
+ */
+static void gpiochip_set_hierarchical_irqchip(struct gpio_chip *gc,
+					      struct irq_chip *irqchip)
+{
+	/* DT will deal with mapping each IRQ as we go along */
+	if (is_of_node(gc->irq.fwnode))
+		return;
+
+	/*
+	 * This is for legacy and boardfile "irqchip" fwnodes: allocate
+	 * irqs upfront instead of dynamically since we don't have the
+	 * dynamic type of allocation that hardware description languages
+	 * provide. Once all GPIO drivers using board files are gone from
+	 * the kernel we can delete this code, but for a transitional period
+	 * it is necessary to keep this around.
+	 */
+	if (is_fwnode_irqchip(gc->irq.fwnode)) {
+		int i;
+		int ret;
+
+		for (i = 0; i < gc->ngpio; i++) {
+			struct irq_fwspec fwspec;
+			unsigned int parent_hwirq;
+			unsigned int parent_type;
+			struct gpio_irq_chip *girq = &gc->irq;
+
+			/*
+			 * We call the child to parent translation function
+			 * only to check if the child IRQ is valid or not.
+			 * Just pick the rising edge type here as that is what
+			 * we likely need to support.
+			 */
+			ret = girq->child_to_parent_hwirq(gc, i,
+							  IRQ_TYPE_EDGE_RISING,
+							  &parent_hwirq,
+							  &parent_type);
+			if (ret) {
+				chip_err(gc, "skip set-up on hwirq %d\n",
+					 i);
+				continue;
+			}
+
+			fwspec.fwnode = gc->irq.fwnode;
+			/* This is the hwirq for the GPIO line side of things */
+			fwspec.param[0] = girq->child_offset_to_irq(gc, i);
+			/* Just pick something */
+			fwspec.param[1] = IRQ_TYPE_EDGE_RISING;
+			fwspec.param_count = 2;
+			ret = __irq_domain_alloc_irqs(gc->irq.domain,
+						      /* just pick something */
+						      -1,
+						      1,
+						      NUMA_NO_NODE,
+						      &fwspec,
+						      false,
+						      NULL);
+			if (ret < 0) {
+				chip_err(gc,
+					 "can not allocate irq for GPIO line %d parent hwirq %d in hierarchy domain: %d\n",
+					 i, parent_hwirq,
+					 ret);
+			}
+		}
+	}
+
+	chip_err(gc, "%s unknown fwnode type proceed anyway\n", __func__);
+
+	return;
+}
+
+static int gpiochip_hierarchy_irq_domain_translate(struct irq_domain *d,
+						   struct irq_fwspec *fwspec,
+						   unsigned long *hwirq,
+						   unsigned int *type)
+{
+	/* We support standard DT translation */
+	if (is_of_node(fwspec->fwnode) && fwspec->param_count == 2) {
+		return irq_domain_translate_twocell(d, fwspec, hwirq, type);
+	}
+
+	/* This is for board files and others not using DT */
+	if (is_fwnode_irqchip(fwspec->fwnode)) {
+		int ret;
+
+		ret = irq_domain_translate_twocell(d, fwspec, hwirq, type);
+		if (ret)
+			return ret;
+		WARN_ON(*type == IRQ_TYPE_NONE);
+		return 0;
+	}
+	return -EINVAL;
+}
+
+static int gpiochip_hierarchy_irq_domain_alloc(struct irq_domain *d,
+					       unsigned int irq,
+					       unsigned int nr_irqs,
+					       void *data)
+{
+	struct gpio_chip *gc = d->host_data;
+	irq_hw_number_t hwirq;
+	unsigned int type = IRQ_TYPE_NONE;
+	struct irq_fwspec *fwspec = data;
+	struct irq_fwspec parent_fwspec;
+	unsigned int parent_hwirq;
+	unsigned int parent_type;
+	struct gpio_irq_chip *girq = &gc->irq;
+	int ret;
+
+	/*
+	 * The nr_irqs parameter is always one except for PCI multi-MSI
+	 * so this should not happen.
+	 */
+	WARN_ON(nr_irqs != 1);
+
+	ret = gc->irq.child_irq_domain_ops.translate(d, fwspec, &hwirq, &type);
+	if (ret)
+		return ret;
+
+	chip_info(gc, "allocate IRQ %d, hwirq %lu\n", irq,  hwirq);
+
+	ret = girq->child_to_parent_hwirq(gc, hwirq, type,
+					  &parent_hwirq, &parent_type);
+	if (ret) {
+		chip_err(gc, "can't look up hwirq %lu\n", hwirq);
+		return ret;
+	}
+	chip_info(gc, "found parent hwirq %u\n", parent_hwirq);
+
+	/*
+	 * We set handle_bad_irq because the .set_type() should
+	 * always be invoked and set the right type of handler.
+	 */
+	irq_domain_set_info(d,
+			    irq,
+			    hwirq,
+			    gc->irq.chip,
+			    gc,
+			    girq->handler,
+			    NULL, NULL);
+	irq_set_probe(irq);
+
+	/*
+	 * Create a IRQ fwspec to send up to the parent irqdomain:
+	 * specify the hwirq we address on the parent and tie it
+	 * all together up the chain.
+	 */
+	parent_fwspec.fwnode = d->parent->fwnode;
+	/* This parent only handles asserted level IRQs */
+	girq->populate_parent_fwspec(gc, &parent_fwspec, parent_hwirq,
+				     parent_type);
+	chip_info(gc, "alloc_irqs_parent for %d parent hwirq %d\n",
+		  irq, parent_hwirq);
+	ret = irq_domain_alloc_irqs_parent(d, irq, 1, &parent_fwspec);
+	if (ret)
+		chip_err(gc,
+			 "failed to allocate parent hwirq %d for hwirq %lu\n",
+			 parent_hwirq, hwirq);
+
+	return ret;
+}
+
+static unsigned int gpiochip_child_offset_to_irq_noop(struct gpio_chip *chip,
+						      unsigned int offset)
+{
+	return offset;
+}
+
+static void gpiochip_hierarchy_setup_domain_ops(struct irq_domain_ops *ops)
+{
+	ops->activate = gpiochip_irq_domain_activate;
+	ops->deactivate = gpiochip_irq_domain_deactivate;
+	ops->alloc = gpiochip_hierarchy_irq_domain_alloc;
+	ops->free = irq_domain_free_irqs_common;
+
+	/*
+	 * We only allow overriding the translate() function for
+	 * hierarchical chips, and this should only be done if the user
+	 * really need something other than 1:1 translation.
+	 */
+	if (!ops->translate)
+		ops->translate = gpiochip_hierarchy_irq_domain_translate;
+}
+
+static int gpiochip_hierarchy_add_domain(struct gpio_chip *gc)
+{
+	if (!gc->irq.child_to_parent_hwirq ||
+	    !gc->irq.fwnode) {
+		chip_err(gc, "missing irqdomain vital data\n");
+		return -EINVAL;
+	}
+
+	if (!gc->irq.child_offset_to_irq)
+		gc->irq.child_offset_to_irq = gpiochip_child_offset_to_irq_noop;
+
+	if (!gc->irq.populate_parent_fwspec)
+		gc->irq.populate_parent_fwspec =
+			gpiochip_populate_parent_fwspec_twocell;
+
+	gpiochip_hierarchy_setup_domain_ops(&gc->irq.child_irq_domain_ops);
+
+	gc->irq.domain = irq_domain_create_hierarchy(
+		gc->irq.parent_domain,
+		0,
+		gc->ngpio,
+		gc->irq.fwnode,
+		&gc->irq.child_irq_domain_ops,
+		gc);
+
+	if (!gc->irq.domain)
+		return -ENOMEM;
+
+	gpiochip_set_hierarchical_irqchip(gc, gc->irq.chip);
+
+	return 0;
+}
+
+static bool gpiochip_hierarchy_is_hierarchical(struct gpio_chip *gc)
+{
+	return !!gc->irq.parent_domain;
+}
+
+void gpiochip_populate_parent_fwspec_twocell(struct gpio_chip *chip,
+					     struct irq_fwspec *fwspec,
+					     unsigned int parent_hwirq,
+					     unsigned int parent_type)
+{
+	fwspec->param_count = 2;
+	fwspec->param[0] = parent_hwirq;
+	fwspec->param[1] = parent_type;
+}
+EXPORT_SYMBOL_GPL(gpiochip_populate_parent_fwspec_twocell);
+
+void gpiochip_populate_parent_fwspec_fourcell(struct gpio_chip *chip,
+					      struct irq_fwspec *fwspec,
+					      unsigned int parent_hwirq,
+					      unsigned int parent_type)
+{
+	fwspec->param_count = 4;
+	fwspec->param[0] = 0;
+	fwspec->param[1] = parent_hwirq;
+	fwspec->param[2] = 0;
+	fwspec->param[3] = parent_type;
+}
+EXPORT_SYMBOL_GPL(gpiochip_populate_parent_fwspec_fourcell);
+
+#else
+
+static int gpiochip_hierarchy_add_domain(struct gpio_chip *gc)
+{
+	return -EINVAL;
+}
+
+static bool gpiochip_hierarchy_is_hierarchical(struct gpio_chip *gc)
+{
+	return false;
+}
+
+#endif /* CONFIG_IRQ_DOMAIN_HIERARCHY */
+
 /**
  * gpiochip_irq_map() - maps an IRQ into a GPIO irqchip
  * @d: the irqdomain used by this irqchip
@@ -1788,6 +2055,11 @@ static const struct irq_domain_ops gpiochip_domain_ops = {
 	.xlate	= irq_domain_xlate_twocell,
 };
 
+/*
+ * TODO: move these activate/deactivate in under the hierarchicial
+ * irqchip implementation as static once SPMI and SSBI (all external
+ * users) are phased over.
+ */
 /**
  * gpiochip_irq_domain_activate() - Lock a GPIO to be used as an IRQ
  * @domain: The IRQ domain used by this IRQ chip
@@ -1827,10 +2099,25 @@ EXPORT_SYMBOL_GPL(gpiochip_irq_domain_deactivate);
 
 static int gpiochip_to_irq(struct gpio_chip *chip, unsigned offset)
 {
+	struct irq_domain *domain = chip->irq.domain;
+
 	if (!gpiochip_irqchip_irq_valid(chip, offset))
 		return -ENXIO;
 
-	return irq_create_mapping(chip->irq.domain, offset);
+#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
+	if (irq_domain_is_hierarchy(domain)) {
+		struct irq_fwspec spec;
+
+		spec.fwnode = domain->fwnode;
+		spec.param_count = 2;
+		spec.param[0] = chip->irq.child_offset_to_irq(chip, offset);
+		spec.param[1] = IRQ_TYPE_NONE;
+
+		return irq_create_fwspec_mapping(&spec);
+	}
+#endif
+
+	return irq_create_mapping(domain, offset);
 }
 
 static int gpiochip_irq_reqres(struct irq_data *d)
@@ -1907,7 +2194,7 @@ static int gpiochip_add_irqchip(struct gpio_chip *gpiochip,
 				struct lock_class_key *request_key)
 {
 	struct irq_chip *irqchip = gpiochip->irq.chip;
-	const struct irq_domain_ops *ops;
+	const struct irq_domain_ops *ops = NULL;
 	struct device_node *np;
 	unsigned int type;
 	unsigned int i;
@@ -1943,16 +2230,25 @@ static int gpiochip_add_irqchip(struct gpio_chip *gpiochip,
 	gpiochip->irq.lock_key = lock_key;
 	gpiochip->irq.request_key = request_key;
 
-	if (gpiochip->irq.domain_ops)
-		ops = gpiochip->irq.domain_ops;
-	else
-		ops = &gpiochip_domain_ops;
-
-	gpiochip->irq.domain = irq_domain_add_simple(np, gpiochip->ngpio,
-						     gpiochip->irq.first,
-						     ops, gpiochip);
-	if (!gpiochip->irq.domain)
-		return -EINVAL;
+	/* If a parent irqdomain is provided, let's build a hierarchy */
+	if (gpiochip_hierarchy_is_hierarchical(gpiochip)) {
+		int ret = gpiochip_hierarchy_add_domain(gpiochip);
+		if (ret)
+			return ret;
+	} else {
+		/* Some drivers provide custom irqdomain ops */
+		if (gpiochip->irq.domain_ops)
+			ops = gpiochip->irq.domain_ops;
+
+		if (!ops)
+			ops = &gpiochip_domain_ops;
+		gpiochip->irq.domain = irq_domain_add_simple(np,
+			gpiochip->ngpio,
+			gpiochip->irq.first,
+			ops, gpiochip);
+		if (!gpiochip->irq.domain)
+			return -EINVAL;
+	}
 
 	if (gpiochip->irq.parent_handler) {
 		void *data = gpiochip->irq.parent_handler_data ?: gpiochip;