Documentation: Update the recommended pattern for GPIO irqchips
Update the documentation to get rid of the per-gpio_irq_chip irq_chip structure, and give examples of the new pattern. Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Reviewed-by: Bartosz Golaszewski <brgl@bgdev.pl> Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20220419141846.598305-11-maz@kernel.org
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Marc Zyngier
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5644b66a9c
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@ -417,30 +417,66 @@ struct gpio_irq_chip inside struct gpio_chip before adding the gpio_chip.
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If you do this, the additional irq_chip will be set up by gpiolib at the
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same time as setting up the rest of the GPIO functionality. The following
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is a typical example of a chained cascaded interrupt handler using
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the gpio_irq_chip:
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the gpio_irq_chip. Note how the mask/unmask (or disable/enable) functions
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call into the core gpiolib code:
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.. code-block:: c
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/* Typical state container with dynamic irqchip */
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/* Typical state container */
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struct my_gpio {
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struct gpio_chip gc;
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struct irq_chip irq;
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};
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static void my_gpio_mask_irq(struct irq_data *d)
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{
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struct gpio_chip *gc = irq_desc_get_handler_data(d);
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/*
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* Perform any necessary action to mask the interrupt,
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* and then call into the core code to synchronise the
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* state.
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*/
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gpiochip_disable_irq(gc, d->hwirq);
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}
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static void my_gpio_unmask_irq(struct irq_data *d)
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{
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struct gpio_chip *gc = irq_desc_get_handler_data(d);
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gpiochip_enable_irq(gc, d->hwirq);
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/*
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* Perform any necessary action to unmask the interrupt,
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* after having called into the core code to synchronise
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* the state.
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*/
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}
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/*
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* Statically populate the irqchip. Note that it is made const
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* (further indicated by the IRQCHIP_IMMUTABLE flag), and that
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* the GPIOCHIP_IRQ_RESOURCE_HELPER macro adds some extra
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* callbacks to the structure.
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*/
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static const struct irq_chip my_gpio_irq_chip = {
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.name = "my_gpio_irq",
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.irq_ack = my_gpio_ack_irq,
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.irq_mask = my_gpio_mask_irq,
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.irq_unmask = my_gpio_unmask_irq,
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.irq_set_type = my_gpio_set_irq_type,
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.flags = IRQCHIP_IMMUTABLE,
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/* Provide the gpio resource callbacks */
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GPIOCHIP_IRQ_RESOURCE_HELPERS,
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};
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int irq; /* from platform etc */
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struct my_gpio *g;
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struct gpio_irq_chip *girq;
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/* Set up the irqchip dynamically */
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g->irq.name = "my_gpio_irq";
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g->irq.irq_ack = my_gpio_ack_irq;
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g->irq.irq_mask = my_gpio_mask_irq;
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g->irq.irq_unmask = my_gpio_unmask_irq;
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g->irq.irq_set_type = my_gpio_set_irq_type;
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/* Get a pointer to the gpio_irq_chip */
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girq = &g->gc.irq;
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girq->chip = &g->irq;
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gpio_irq_chip_set_chip(girq, &my_gpio_irq_chip);
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girq->parent_handler = ftgpio_gpio_irq_handler;
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girq->num_parents = 1;
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girq->parents = devm_kcalloc(dev, 1, sizeof(*girq->parents),
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@ -458,23 +494,58 @@ the interrupt separately and go with it:
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.. code-block:: c
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/* Typical state container with dynamic irqchip */
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/* Typical state container */
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struct my_gpio {
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struct gpio_chip gc;
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struct irq_chip irq;
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};
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static void my_gpio_mask_irq(struct irq_data *d)
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{
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struct gpio_chip *gc = irq_desc_get_handler_data(d);
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/*
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* Perform any necessary action to mask the interrupt,
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* and then call into the core code to synchronise the
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* state.
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*/
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gpiochip_disable_irq(gc, d->hwirq);
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}
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static void my_gpio_unmask_irq(struct irq_data *d)
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{
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struct gpio_chip *gc = irq_desc_get_handler_data(d);
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gpiochip_enable_irq(gc, d->hwirq);
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/*
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* Perform any necessary action to unmask the interrupt,
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* after having called into the core code to synchronise
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* the state.
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*/
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}
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/*
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* Statically populate the irqchip. Note that it is made const
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* (further indicated by the IRQCHIP_IMMUTABLE flag), and that
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* the GPIOCHIP_IRQ_RESOURCE_HELPER macro adds some extra
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* callbacks to the structure.
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*/
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static const struct irq_chip my_gpio_irq_chip = {
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.name = "my_gpio_irq",
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.irq_ack = my_gpio_ack_irq,
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.irq_mask = my_gpio_mask_irq,
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.irq_unmask = my_gpio_unmask_irq,
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.irq_set_type = my_gpio_set_irq_type,
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.flags = IRQCHIP_IMMUTABLE,
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/* Provide the gpio resource callbacks */
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GPIOCHIP_IRQ_RESOURCE_HELPERS,
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};
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int irq; /* from platform etc */
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struct my_gpio *g;
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struct gpio_irq_chip *girq;
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/* Set up the irqchip dynamically */
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g->irq.name = "my_gpio_irq";
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g->irq.irq_ack = my_gpio_ack_irq;
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g->irq.irq_mask = my_gpio_mask_irq;
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g->irq.irq_unmask = my_gpio_unmask_irq;
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g->irq.irq_set_type = my_gpio_set_irq_type;
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ret = devm_request_threaded_irq(dev, irq, NULL,
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irq_thread_fn, IRQF_ONESHOT, "my-chip", g);
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if (ret < 0)
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@ -482,7 +553,7 @@ the interrupt separately and go with it:
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/* Get a pointer to the gpio_irq_chip */
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girq = &g->gc.irq;
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girq->chip = &g->irq;
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gpio_irq_chip_set_chip(girq, &my_gpio_irq_chip);
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/* This will let us handle the parent IRQ in the driver */
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girq->parent_handler = NULL;
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girq->num_parents = 0;
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@ -500,24 +571,61 @@ In this case the typical set-up will look like this:
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/* Typical state container with dynamic irqchip */
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struct my_gpio {
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struct gpio_chip gc;
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struct irq_chip irq;
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struct fwnode_handle *fwnode;
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};
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int irq; /* from platform etc */
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static void my_gpio_mask_irq(struct irq_data *d)
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{
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struct gpio_chip *gc = irq_desc_get_handler_data(d);
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/*
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* Perform any necessary action to mask the interrupt,
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* and then call into the core code to synchronise the
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* state.
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*/
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gpiochip_disable_irq(gc, d->hwirq);
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irq_mask_mask_parent(d);
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}
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static void my_gpio_unmask_irq(struct irq_data *d)
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{
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struct gpio_chip *gc = irq_desc_get_handler_data(d);
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gpiochip_enable_irq(gc, d->hwirq);
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/*
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* Perform any necessary action to unmask the interrupt,
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* after having called into the core code to synchronise
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* the state.
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*/
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irq_mask_unmask_parent(d);
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}
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/*
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* Statically populate the irqchip. Note that it is made const
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* (further indicated by the IRQCHIP_IMMUTABLE flag), and that
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* the GPIOCHIP_IRQ_RESOURCE_HELPER macro adds some extra
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* callbacks to the structure.
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*/
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static const struct irq_chip my_gpio_irq_chip = {
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.name = "my_gpio_irq",
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.irq_ack = my_gpio_ack_irq,
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.irq_mask = my_gpio_mask_irq,
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.irq_unmask = my_gpio_unmask_irq,
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.irq_set_type = my_gpio_set_irq_type,
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.flags = IRQCHIP_IMMUTABLE,
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/* Provide the gpio resource callbacks */
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GPIOCHIP_IRQ_RESOURCE_HELPERS,
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};
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struct my_gpio *g;
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struct gpio_irq_chip *girq;
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/* Set up the irqchip dynamically */
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g->irq.name = "my_gpio_irq";
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g->irq.irq_ack = my_gpio_ack_irq;
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g->irq.irq_mask = my_gpio_mask_irq;
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g->irq.irq_unmask = my_gpio_unmask_irq;
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g->irq.irq_set_type = my_gpio_set_irq_type;
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/* Get a pointer to the gpio_irq_chip */
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girq = &g->gc.irq;
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girq->chip = &g->irq;
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gpio_irq_chip_set_chip(girq, &my_gpio_irq_chip);
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girq->default_type = IRQ_TYPE_NONE;
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girq->handler = handle_bad_irq;
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girq->fwnode = g->fwnode;
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@ -605,8 +713,9 @@ When implementing an irqchip inside a GPIO driver, these two functions should
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typically be called in the .irq_disable() and .irq_enable() callbacks from the
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irqchip.
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When using the gpiolib irqchip helpers, these callbacks are automatically
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assigned.
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When IRQCHIP_IMMUTABLE is not advertised by the irqchip, these callbacks
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are automatically assigned. This behaviour is deprecated and on its way
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to be removed from the kernel.
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Real-Time compliance for GPIO IRQ chips
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