genirq/irq_sim: Simplify the API

The interrupt simulator API exposes a lot of custom data structures and
functions and doesn't reuse the interfaces already exposed by the irq
subsystem. This patch tries to address it.

We hide all the simulator-related data structures from users and instead
rely on the well-known irq domain. When creating the interrupt simulator
the user receives a pointer to a newly created irq_domain and can use it
to create mappings for simulated interrupts.

It is also possible to pass a handle to fwnode when creating the simulator
domain and retrieve it using irq_find_matching_fwnode().

The irq_sim_fire() function is dropped as well. Instead we implement the
irq_get/set_irqchip_state interface.

We modify the two modules that use the simulator at the same time as
adding these changes in order to reduce the intermediate bloat that would
result when trying to migrate the drivers in separate patches.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> #for IIO
Link: https://lore.kernel.org/r/20200514083901.23445-3-brgl@bgdev.pl

2 files changed, 166 insertions, 102 deletions

diff --git a/kernel/irq/Kconfig b/kernel/irq/Kconfig
index 20d501af4f2e..d63c324895ea 100644
--- a/kernel/irq/Kconfig
+++ b/kernel/irq/Kconfig
@@ -72,6 +72,7 @@ config IRQ_DOMAIN
 config IRQ_SIM
 	bool
 	select IRQ_WORK
+	select IRQ_DOMAIN
 
 # Support for hierarchical irq domains
 config IRQ_DOMAIN_HIERARCHY
diff --git a/kernel/irq/irq_sim.c b/kernel/irq/irq_sim.c
index b992f88c5613..48006608baf0 100644
--- a/kernel/irq/irq_sim.c
+++ b/kernel/irq/irq_sim.c
@@ -1,14 +1,31 @@
 // SPDX-License-Identifier: GPL-2.0+
 /*
  * Copyright (C) 2017-2018 Bartosz Golaszewski <brgl@bgdev.pl>
+ * Copyright (C) 2020 Bartosz Golaszewski <bgolaszewski@baylibre.com>
  */
 
-#include <linux/slab.h>
-#include <linux/irq_sim.h>
 #include <linux/irq.h>
+#include <linux/irq_sim.h>
+#include <linux/irq_work.h>
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+
+struct irq_sim_work_ctx {
+	struct irq_work		work;
+	int			irq_base;
+	unsigned int		irq_count;
+	unsigned long		*pending;
+	struct irq_domain	*domain;
+};
+
+struct irq_sim_irq_ctx {
+	int			irqnum;
+	bool			enabled;
+	struct irq_sim_work_ctx	*work_ctx;
+};
 
 struct irq_sim_devres {
-	struct irq_sim		*sim;
+	struct irq_domain	*domain;
 };
 
 static void irq_sim_irqmask(struct irq_data *data)
@@ -36,159 +53,205 @@ static int irq_sim_set_type(struct irq_data *data, unsigned int type)
 	return 0;
 }
 
+static int irq_sim_get_irqchip_state(struct irq_data *data,
+				     enum irqchip_irq_state which, bool *state)
+{
+	struct irq_sim_irq_ctx *irq_ctx = irq_data_get_irq_chip_data(data);
+	irq_hw_number_t hwirq = irqd_to_hwirq(data);
+
+	switch (which) {
+	case IRQCHIP_STATE_PENDING:
+		if (irq_ctx->enabled)
+			*state = test_bit(hwirq, irq_ctx->work_ctx->pending);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int irq_sim_set_irqchip_state(struct irq_data *data,
+				     enum irqchip_irq_state which, bool state)
+{
+	struct irq_sim_irq_ctx *irq_ctx = irq_data_get_irq_chip_data(data);
+	irq_hw_number_t hwirq = irqd_to_hwirq(data);
+
+	switch (which) {
+	case IRQCHIP_STATE_PENDING:
+		if (irq_ctx->enabled) {
+			assign_bit(hwirq, irq_ctx->work_ctx->pending, state);
+			if (state)
+				irq_work_queue(&irq_ctx->work_ctx->work);
+		}
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 static struct irq_chip irq_sim_irqchip = {
-	.name		= "irq_sim",
-	.irq_mask	= irq_sim_irqmask,
-	.irq_unmask	= irq_sim_irqunmask,
-	.irq_set_type	= irq_sim_set_type,
+	.name			= "irq_sim",
+	.irq_mask		= irq_sim_irqmask,
+	.irq_unmask		= irq_sim_irqunmask,
+	.irq_set_type		= irq_sim_set_type,
+	.irq_get_irqchip_state	= irq_sim_get_irqchip_state,
+	.irq_set_irqchip_state	= irq_sim_set_irqchip_state,
 };
 
 static void irq_sim_handle_irq(struct irq_work *work)
 {
 	struct irq_sim_work_ctx *work_ctx;
 	unsigned int offset = 0;
-	struct irq_sim *sim;
 	int irqnum;
 
 	work_ctx = container_of(work, struct irq_sim_work_ctx, work);
-	sim = container_of(work_ctx, struct irq_sim, work_ctx);
 
-	while (!bitmap_empty(work_ctx->pending, sim->irq_count)) {
+	while (!bitmap_empty(work_ctx->pending, work_ctx->irq_count)) {
 		offset = find_next_bit(work_ctx->pending,
-				       sim->irq_count, offset);
+				       work_ctx->irq_count, offset);
 		clear_bit(offset, work_ctx->pending);
-		irqnum = irq_sim_irqnum(sim, offset);
+		irqnum = irq_find_mapping(work_ctx->domain, offset);
 		handle_simple_irq(irq_to_desc(irqnum));
 	}
 }
 
+static int irq_sim_domain_map(struct irq_domain *domain,
+			      unsigned int virq, irq_hw_number_t hw)
+{
+	struct irq_sim_work_ctx *work_ctx = domain->host_data;
+	struct irq_sim_irq_ctx *irq_ctx;
+
+	irq_ctx = kzalloc(sizeof(*irq_ctx), GFP_KERNEL);
+	if (!irq_ctx)
+		return -ENOMEM;
+
+	irq_set_chip(virq, &irq_sim_irqchip);
+	irq_set_chip_data(virq, irq_ctx);
+	irq_set_handler(virq, handle_simple_irq);
+	irq_modify_status(virq, IRQ_NOREQUEST | IRQ_NOAUTOEN, IRQ_NOPROBE);
+	irq_ctx->work_ctx = work_ctx;
+
+	return 0;
+}
+
+static void irq_sim_domain_unmap(struct irq_domain *domain, unsigned int virq)
+{
+	struct irq_sim_irq_ctx *irq_ctx;
+	struct irq_data *irqd;
+
+	irqd = irq_domain_get_irq_data(domain, virq);
+	irq_ctx = irq_data_get_irq_chip_data(irqd);
+
+	irq_set_handler(virq, NULL);
+	irq_domain_reset_irq_data(irqd);
+	kfree(irq_ctx);
+}
+
+static const struct irq_domain_ops irq_sim_domain_ops = {
+	.map		= irq_sim_domain_map,
+	.unmap		= irq_sim_domain_unmap,
+};
+
 /**
- * irq_sim_init - Initialize the interrupt simulator: allocate a range of
- *                dummy interrupts.
+ * irq_domain_create_sim - Create a new interrupt simulator irq_domain and
+ *                         allocate a range of dummy interrupts.
  *
- * @sim:        The interrupt simulator object to initialize.
- * @num_irqs:   Number of interrupts to allocate
+ * @fnode:      struct fwnode_handle to be associated with this domain.
+ * @num_irqs:   Number of interrupts to allocate.
  *
- * On success: return the base of the allocated interrupt range.
- * On failure: a negative errno.
+ * On success: return a new irq_domain object.
+ * On failure: a negative errno wrapped with ERR_PTR().
  */
-int irq_sim_init(struct irq_sim *sim, unsigned int num_irqs)
+struct irq_domain *irq_domain_create_sim(struct fwnode_handle *fwnode,
+					 unsigned int num_irqs)
 {
-	int i;
+	struct irq_sim_work_ctx *work_ctx;
 
-	sim->irqs = kmalloc_array(num_irqs, sizeof(*sim->irqs), GFP_KERNEL);
-	if (!sim->irqs)
-		return -ENOMEM;
+	work_ctx = kmalloc(sizeof(*work_ctx), GFP_KERNEL);
+	if (!work_ctx)
+		goto err_out;
 
-	sim->irq_base = irq_alloc_descs(-1, 0, num_irqs, 0);
-	if (sim->irq_base < 0) {
-		kfree(sim->irqs);
-		return sim->irq_base;
-	}
+	work_ctx->pending = bitmap_zalloc(num_irqs, GFP_KERNEL);
+	if (!work_ctx->pending)
+		goto err_free_work_ctx;
 
-	sim->work_ctx.pending = bitmap_zalloc(num_irqs, GFP_KERNEL);
-	if (!sim->work_ctx.pending) {
-		kfree(sim->irqs);
-		irq_free_descs(sim->irq_base, num_irqs);
-		return -ENOMEM;
-	}
+	work_ctx->domain = irq_domain_create_linear(fwnode, num_irqs,
+						    &irq_sim_domain_ops,
+						    work_ctx);
+	if (!work_ctx->domain)
+		goto err_free_bitmap;
 
-	for (i = 0; i < num_irqs; i++) {
-		sim->irqs[i].irqnum = sim->irq_base + i;
-		sim->irqs[i].enabled = false;
-		irq_set_chip(sim->irq_base + i, &irq_sim_irqchip);
-		irq_set_chip_data(sim->irq_base + i, &sim->irqs[i]);
-		irq_set_handler(sim->irq_base + i, &handle_simple_irq);
-		irq_modify_status(sim->irq_base + i,
-				  IRQ_NOREQUEST | IRQ_NOAUTOEN, IRQ_NOPROBE);
-	}
+	work_ctx->irq_count = num_irqs;
+	init_irq_work(&work_ctx->work, irq_sim_handle_irq);
 
-	init_irq_work(&sim->work_ctx.work, irq_sim_handle_irq);
-	sim->irq_count = num_irqs;
+	return work_ctx->domain;
 
-	return sim->irq_base;
+err_free_bitmap:
+	bitmap_free(work_ctx->pending);
+err_free_work_ctx:
+	kfree(work_ctx);
+err_out:
+	return ERR_PTR(-ENOMEM);
 }
-EXPORT_SYMBOL_GPL(irq_sim_init);
+EXPORT_SYMBOL_GPL(irq_domain_create_sim);
 
 /**
- * irq_sim_fini - Deinitialize the interrupt simulator: free the interrupt
- *                descriptors and allocated memory.
+ * irq_domain_remove_sim - Deinitialize the interrupt simulator domain: free
+ *                         the interrupt descriptors and allocated memory.
  *
- * @sim:        The interrupt simulator to tear down.
+ * @domain:     The interrupt simulator domain to tear down.
  */
-void irq_sim_fini(struct irq_sim *sim)
+void irq_domain_remove_sim(struct irq_domain *domain)
 {
-	irq_work_sync(&sim->work_ctx.work);
-	bitmap_free(sim->work_ctx.pending);
-	irq_free_descs(sim->irq_base, sim->irq_count);
-	kfree(sim->irqs);
+	struct irq_sim_work_ctx *work_ctx = domain->host_data;
+
+	irq_work_sync(&work_ctx->work);
+	bitmap_free(work_ctx->pending);
+	kfree(work_ctx);
+
+	irq_domain_remove(domain);
 }
-EXPORT_SYMBOL_GPL(irq_sim_fini);
+EXPORT_SYMBOL_GPL(irq_domain_remove_sim);
 
-static void devm_irq_sim_release(struct device *dev, void *res)
+static void devm_irq_domain_release_sim(struct device *dev, void *res)
 {
 	struct irq_sim_devres *this = res;
 
-	irq_sim_fini(this->sim);
+	irq_domain_remove_sim(this->domain);
 }
 
 /**
- * irq_sim_init - Initialize the interrupt simulator for a managed device.
+ * devm_irq_domain_create_sim - Create a new interrupt simulator for
+ *                              a managed device.
  *
  * @dev:        Device to initialize the simulator object for.
- * @sim:        The interrupt simulator object to initialize.
+ * @fnode:      struct fwnode_handle to be associated with this domain.
  * @num_irqs:   Number of interrupts to allocate
  *
- * On success: return the base of the allocated interrupt range.
- * On failure: a negative errno.
+ * On success: return a new irq_domain object.
+ * On failure: a negative errno wrapped with ERR_PTR().
  */
-int devm_irq_sim_init(struct device *dev, struct irq_sim *sim,
-		      unsigned int num_irqs)
+struct irq_domain *devm_irq_domain_create_sim(struct device *dev,
+					      struct fwnode_handle *fwnode,
+					      unsigned int num_irqs)
 {
 	struct irq_sim_devres *dr;
-	int rv;
 
-	dr = devres_alloc(devm_irq_sim_release, sizeof(*dr), GFP_KERNEL);
+	dr = devres_alloc(devm_irq_domain_release_sim,
+			  sizeof(*dr), GFP_KERNEL);
 	if (!dr)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
-	rv = irq_sim_init(sim, num_irqs);
-	if (rv < 0) {
+	dr->domain = irq_domain_create_sim(fwnode, num_irqs);
+	if (IS_ERR(dr->domain)) {
 		devres_free(dr);
-		return rv;
+		return dr->domain;
 	}
 
-	dr->sim = sim;
 	devres_add(dev, dr);
-
-	return rv;
-}
-EXPORT_SYMBOL_GPL(devm_irq_sim_init);
-
-/**
- * irq_sim_fire - Enqueue an interrupt.
- *
- * @sim:        The interrupt simulator object.
- * @offset:     Offset of the simulated interrupt which should be fired.
- */
-void irq_sim_fire(struct irq_sim *sim, unsigned int offset)
-{
-	if (sim->irqs[offset].enabled) {
-		set_bit(offset, sim->work_ctx.pending);
-		irq_work_queue(&sim->work_ctx.work);
-	}
-}
-EXPORT_SYMBOL_GPL(irq_sim_fire);
-
-/**
- * irq_sim_irqnum - Get the allocated number of a dummy interrupt.
- *
- * @sim:        The interrupt simulator object.
- * @offset:     Offset of the simulated interrupt for which to retrieve
- *              the number.
- */
-int irq_sim_irqnum(struct irq_sim *sim, unsigned int offset)
-{
-	return sim->irqs[offset].irqnum;
+	return dr->domain;
 }
-EXPORT_SYMBOL_GPL(irq_sim_irqnum);
+EXPORT_SYMBOL_GPL(devm_irq_domain_create_sim);