linux-stable/kernel/irq/irq_sim.c
Sebastian Andrzej Siewior 21673fcb25 genirq/irq_sim: Make the irq_work always run in hard irq context
The IRQ simulator uses irq_work to trigger an interrupt. Without the
IRQ_WORK_HARD_IRQ flag the irq_work will be performed in thread context
on PREEMPT_RT. This causes locking errors later in handle_simple_irq()
which expects to be invoked with disabled interrupts.

Triggering individual interrupts in hardirq context should not lead to
unexpected high latencies since this is also what the hardware
controller does. Also it is used as a simulator so...

Use IRQ_WORK_INIT_HARD() to carry out the irq_work in hardirq context on
PREEMPT_RT.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/YnuZBoEVMGwKkLm+@linutronix.de
2022-05-14 17:48:27 +02:00

250 lines
6.2 KiB
C

// 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/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;
};
static void irq_sim_irqmask(struct irq_data *data)
{
struct irq_sim_irq_ctx *irq_ctx = irq_data_get_irq_chip_data(data);
irq_ctx->enabled = false;
}
static void irq_sim_irqunmask(struct irq_data *data)
{
struct irq_sim_irq_ctx *irq_ctx = irq_data_get_irq_chip_data(data);
irq_ctx->enabled = true;
}
static int irq_sim_set_type(struct irq_data *data, unsigned int type)
{
/* We only support rising and falling edge trigger types. */
if (type & ~IRQ_TYPE_EDGE_BOTH)
return -EINVAL;
irqd_set_trigger_type(data, 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,
.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;
int irqnum;
work_ctx = container_of(work, struct irq_sim_work_ctx, work);
while (!bitmap_empty(work_ctx->pending, work_ctx->irq_count)) {
offset = find_next_bit(work_ctx->pending,
work_ctx->irq_count, offset);
clear_bit(offset, work_ctx->pending);
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_domain_create_sim - Create a new interrupt simulator irq_domain and
* allocate a range of dummy interrupts.
*
* @fwnode: struct fwnode_handle to be associated with this domain.
* @num_irqs: Number of interrupts to allocate.
*
* On success: return a new irq_domain object.
* On failure: a negative errno wrapped with ERR_PTR().
*/
struct irq_domain *irq_domain_create_sim(struct fwnode_handle *fwnode,
unsigned int num_irqs)
{
struct irq_sim_work_ctx *work_ctx;
work_ctx = kmalloc(sizeof(*work_ctx), GFP_KERNEL);
if (!work_ctx)
goto err_out;
work_ctx->pending = bitmap_zalloc(num_irqs, GFP_KERNEL);
if (!work_ctx->pending)
goto err_free_work_ctx;
work_ctx->domain = irq_domain_create_linear(fwnode, num_irqs,
&irq_sim_domain_ops,
work_ctx);
if (!work_ctx->domain)
goto err_free_bitmap;
work_ctx->irq_count = num_irqs;
work_ctx->work = IRQ_WORK_INIT_HARD(irq_sim_handle_irq);
return work_ctx->domain;
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_domain_create_sim);
/**
* irq_domain_remove_sim - Deinitialize the interrupt simulator domain: free
* the interrupt descriptors and allocated memory.
*
* @domain: The interrupt simulator domain to tear down.
*/
void irq_domain_remove_sim(struct irq_domain *domain)
{
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_domain_remove_sim);
static void devm_irq_domain_remove_sim(void *data)
{
struct irq_domain *domain = data;
irq_domain_remove_sim(domain);
}
/**
* devm_irq_domain_create_sim - Create a new interrupt simulator for
* a managed device.
*
* @dev: Device to initialize the simulator object for.
* @fwnode: struct fwnode_handle to be associated with this domain.
* @num_irqs: Number of interrupts to allocate
*
* On success: return a new irq_domain object.
* On failure: a negative errno wrapped with ERR_PTR().
*/
struct irq_domain *devm_irq_domain_create_sim(struct device *dev,
struct fwnode_handle *fwnode,
unsigned int num_irqs)
{
struct irq_domain *domain;
int ret;
domain = irq_domain_create_sim(fwnode, num_irqs);
if (IS_ERR(domain))
return domain;
ret = devm_add_action_or_reset(dev, devm_irq_domain_remove_sim, domain);
if (ret)
return ERR_PTR(ret);
return domain;
}
EXPORT_SYMBOL_GPL(devm_irq_domain_create_sim);