Date:   Thu, 28 Sep 2017 09:22:41 -0500
From:   Grygorii Strashko <grygorii.strashko@...com>
To:     Thierry Reding <thierry.reding@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>
CC:     Jonathan Hunter <jonathanh@...dia.com>,
        <linux-gpio@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 01/16] gpio: Implement tighter IRQ chip integration



On 09/28/2017 04:56 AM, Thierry Reding wrote:
> From: Thierry Reding <treding@...dia.com>
> 
> Currently GPIO drivers are required to a GPIO chip and the corresponding
> IRQ chip separately, which can result in a lot of boilerplate. Introduce
> a new struct gpio_irq_chip, embedded in a struct gpio_chip, that drivers
> can fill in if they want the GPIO core to automatically register the IRQ
> chip associated with a GPIO chip.
> 
> Signed-off-by: Thierry Reding <treding@...dia.com>
> ---
>   drivers/gpio/gpiolib.c      | 146 +++++++++++++++++++++++++++++++++++++++++++-
>   include/linux/gpio/driver.h |  64 +++++++++++++++++++
>   2 files changed, 207 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index eb80dac4e26a..b34d9cbd5809 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -72,6 +72,7 @@ static LIST_HEAD(gpio_lookup_list);
>   LIST_HEAD(gpio_devices);
>   
>   static void gpiochip_free_hogs(struct gpio_chip *chip);
> +static int gpiochip_add_irqchip(struct gpio_chip *gpiochip);
>   static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip);
>   static int gpiochip_irqchip_init_valid_mask(struct gpio_chip *gpiochip);
>   static void gpiochip_irqchip_free_valid_mask(struct gpio_chip *gpiochip);
> @@ -1260,6 +1261,10 @@ int gpiochip_add_data(struct gpio_chip *chip, void *data)
>   	if (status)
>   		goto err_remove_from_list;
>   
> +	status = gpiochip_add_irqchip(chip);
> +	if (status)
> +		goto err_remove_chip;
> +
>   	status = of_gpiochip_add(chip);
>   	if (status)
>   		goto err_remove_chip;
> @@ -1626,8 +1631,8 @@ EXPORT_SYMBOL_GPL(gpiochip_set_nested_irqchip);
>    * gpiochip by assigning the gpiochip as chip data, and using the irqchip
>    * stored inside the gpiochip.
>    */
> -static int gpiochip_irq_map(struct irq_domain *d, unsigned int irq,
> -			    irq_hw_number_t hwirq)
> +int gpiochip_irq_map(struct irq_domain *d, unsigned int irq,
> +		     irq_hw_number_t hwirq)
>   {
>   	struct gpio_chip *chip = d->host_data;
>   
> @@ -1655,8 +1660,9 @@ static int gpiochip_irq_map(struct irq_domain *d, unsigned int irq,
>   
>   	return 0;
>   }
> +EXPORT_SYMBOL_GPL(gpiochip_irq_map);
>   
> -static void gpiochip_irq_unmap(struct irq_domain *d, unsigned int irq)
> +void gpiochip_irq_unmap(struct irq_domain *d, unsigned int irq)
>   {
>   	struct gpio_chip *chip = d->host_data;
>   
> @@ -1665,6 +1671,7 @@ static void gpiochip_irq_unmap(struct irq_domain *d, unsigned int irq)
>   	irq_set_chip_and_handler(irq, NULL, NULL);
>   	irq_set_chip_data(irq, NULL);
>   }
> +EXPORT_SYMBOL_GPL(gpiochip_irq_unmap);
>   
>   static const struct irq_domain_ops gpiochip_domain_ops = {
>   	.map	= gpiochip_irq_map,
> @@ -1705,6 +1712,124 @@ static int gpiochip_to_irq(struct gpio_chip *chip, unsigned offset)
>   	return irq_create_mapping(chip->irqdomain, offset);
>   }
>   
> +/**
> + * gpiochip_add_irqchip() - adds an IRQ chip to a GPIO chip
> + * @gpiochip: the GPIO chip to add the IRQ chip to
> + */
> +static int gpiochip_add_irqchip(struct gpio_chip *gpiochip)
> +{
> +	struct irq_chip *irqchip = gpiochip->irqchip;
> +	const struct irq_domain_ops *ops;
> +	struct device_node *np;
> +	unsigned int type;
> +	unsigned int i;
> +
> +	if (!irqchip)
> +		return 0;
> +
> +	if (gpiochip->irq.parent_handler && gpiochip->can_sleep) {
> +		chip_err(gpiochip, "you cannot have chained interrupts on a "
> +			 "chip that may sleep\n");
> +		return -EINVAL;
> +	}
> +
> +	type = gpiochip->irq_default_type;
> +	np = gpiochip->parent->of_node;
> +
> +#ifdef CONFIG_OF_GPIO
> +	/*
> +	 * If the gpiochip has an assigned OF node this takes precedence
> +	 * FIXME: get rid of this and use gpiochip->parent->of_node
> +	 * everywhere
> +	 */
> +	if (gpiochip->of_node)
> +		np = gpiochip->of_node;
> +#endif
> +
> +	/*
> +	 * Specifying a default trigger is a terrible idea if DT or ACPI is
> +	 * used to configure the interrupts, as you may end up with
> +	 * conflicting triggers. Tell the user, and reset to NONE.
> +	 */
> +	if (WARN(np && type != IRQ_TYPE_NONE,
> +		 "%s: Ignoring %u default trigger\n", np->full_name, type))
> +		type = IRQ_TYPE_NONE;
> +
> +	if (has_acpi_companion(gpiochip->parent) && type != IRQ_TYPE_NONE) {
> +		acpi_handle_warn(ACPI_HANDLE(gpiochip->parent),
> +				 "Ignoring %u default trigger\n", type);
> +		type = IRQ_TYPE_NONE;
> +	}
> +
> +	gpiochip->to_irq = gpiochip_to_irq;
> +	gpiochip->irq_default_type = type;
> +
> +	if (gpiochip->irq.domain_ops)
> +		ops = gpiochip->irq.domain_ops;
> +	else
> +		ops = &gpiochip_domain_ops;
> +
> +	gpiochip->irqdomain = irq_domain_add_simple(np, gpiochip->ngpio,
> +						    gpiochip->irq_base,
> +						    ops, gpiochip);
> +	if (!gpiochip->irqdomain)
> +		return -EINVAL;
> +
> +	/*
> +	 * It is possible for a driver to override this, but only if the
> +	 * alternative functions are both implemented.
> +	 */
> +	if (!irqchip->irq_request_resources &&
> +	    !irqchip->irq_release_resources) {
> +		irqchip->irq_request_resources = gpiochip_irq_reqres;
> +		irqchip->irq_release_resources = gpiochip_irq_relres;
> +	}
> +
> +	if (gpiochip->irq.parent_handler) {
> +		void *data = gpiochip->irq.parent_handler_data ?: gpiochip;
> +
> +		for (i = 0; i < gpiochip->irq.num_parents; i++) {
> +			/*
> +			 * The parent IRQ chip is already using the chip_data
> +			 * for this IRQ chip, so our callbacks simply use the
> +			 * handler_data.
> +			 */
> +			irq_set_chained_handler_and_data(gpiochip->irq.parents[i],
> +							 gpiochip->irq.parent_handler,
> +							 data);
> +		}
> +
> +		gpiochip->irq_nested = false;
> +	} else {
> +		gpiochip->irq_nested = true;
> +	}
> +
> +	/*
> +	 * Prepare the mapping since the IRQ chip shall be orthogonal to any
> +	 * GPIO chip calls.
> +	 */
> +	for (i = 0; i < gpiochip->ngpio; i++) {
> +		unsigned int irq;
> +
> +		if (!gpiochip_irqchip_irq_valid(gpiochip, i))
> +			continue;
> +
> +		irq = irq_create_mapping(gpiochip->irqdomain, i);
> +		if (!irq) {
> +			chip_err(gpiochip,
> +				 "failed to create IRQ mapping for GPIO#%u\n",
> +				 i);
> +			continue;
> +		}
> +
> +		irq_set_parent(irq, gpiochip->irq.map[i]);

IRQs should be mapped dynamically.
Pls, see commit dc749a0 "gpiolib: allow gpio irqchip to map irqs dynamically"

> +	}
> +
> +	acpi_gpiochip_request_interrupts(gpiochip);
> +
> +	return 0;
> +}
> +
>   /**
>    * gpiochip_irqchip_remove() - removes an irqchip added to a gpiochip
>    * @gpiochip: the gpiochip to remove the irqchip from
> @@ -1722,6 +1847,16 @@ static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip)
>   		irq_set_handler_data(gpiochip->irq_chained_parent, NULL);
>   	}
>   
> +	if (gpiochip->irqchip) {
> +		struct gpio_irq_chip *irq = &gpiochip->irq;
> +		unsigned int i;
> +
> +		for (i = 0; i < irq->num_parents; i++) {
> +			irq_set_chained_handler(irq->parents[i], NULL);
> +			irq_set_handler_data(irq->parents[i], NULL);
> +		}
> +	}
> +
>   	/* Remove all IRQ mappings and delete the domain */
>   	if (gpiochip->irqdomain) {
>   		for (offset = 0; offset < gpiochip->ngpio; offset++) {
> @@ -1842,6 +1977,11 @@ EXPORT_SYMBOL_GPL(gpiochip_irqchip_add_key);
>   
>   #else /* CONFIG_GPIOLIB_IRQCHIP */
>   
> +static inline int gpiochip_add_irqchip(struct gpio_chip *gpiochip)
> +{
> +	return 0;
> +}
> +
>   static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip) {}
>   static inline int gpiochip_irqchip_init_valid_mask(struct gpio_chip *gpiochip)
>   {
> diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
> index c97f8325e8bf..6100b171817e 100644
> --- a/include/linux/gpio/driver.h
> +++ b/include/linux/gpio/driver.h
> @@ -19,6 +19,58 @@ struct module;
>   
>   #ifdef CONFIG_GPIOLIB
>   
> +#ifdef CONFIG_GPIOLIB_IRQCHIP
> +/**
> + * struct gpio_irq_chip - GPIO interrupt controller
> + */
> +struct gpio_irq_chip {
> +	/**
> +	 * @domain_ops:
> +	 *
> +	 * Table of interrupt domain operations for this IRQ chip.
> +	 */
> +	const struct irq_domain_ops *domain_ops;
> +
> +	/**
> +	 * @parent_handler:
> +	 *
> +	 * The interrupt handler for the GPIO chip's parent interrupts, may be
> +	 * NULL if the parent interrupts are nested rather than cascaded.
> +	 */
> +	irq_flow_handler_t parent_handler;
> +
> +	/**
> +	 * @parent_handler_data:
> +	 *
> +	 * Data associated, and passed to, the handler for the parent
> +	 * interrupt.
> +	 */
> +	void *parent_handler_data;
> +
> +	/**
> +	 * @num_parents:
> +	 *
> +	 * The number of interrupt parents of a GPIO chip.
> +	 */
> +	unsigned int num_parents;
> +
> +	/**
> +	 * @parents:
> +	 *
> +	 * A list of interrupt parents of a GPIO chip. This is owned by the
> +	 * driver, so the core will only reference this list, not modify it.
> +	 */
> +	unsigned int *parents;
> +
> +	/**
> +	 * @map:
> +	 *
> +	 * A list of interrupt parents for each line of a GPIO chip.
> +	 */
> +	unsigned int *map;
> +};
> +#endif
> +
>   /**
>    * struct gpio_chip - abstract a GPIO controller
>    * @label: a functional name for the GPIO device, such as a part
> @@ -173,6 +225,14 @@ struct gpio_chip {
>   	bool			irq_need_valid_mask;
>   	unsigned long		*irq_valid_mask;
>   	struct lock_class_key	*lock_key;
> +
> +	/**
> +	 * @irq:
> +	 *
> +	 * Integrates interrupt chip functionality with the GPIO chip. Can be
> +	 * used to handle IRQs for most practical cases.
> +	 */
> +	struct gpio_irq_chip irq;
>   #endif
>   
>   #if defined(CONFIG_OF_GPIO)
> @@ -264,6 +324,10 @@ int bgpio_init(struct gpio_chip *gc, struct device *dev,
>   
>   #ifdef CONFIG_GPIOLIB_IRQCHIP
>   
> +int gpiochip_irq_map(struct irq_domain *d, unsigned int irq,
> +		     irq_hw_number_t hwirq);
> +void gpiochip_irq_unmap(struct irq_domain *d, unsigned int irq);
> +
>   void gpiochip_set_chained_irqchip(struct gpio_chip *gpiochip,
>   		struct irq_chip *irqchip,
>   		unsigned int parent_irq,
> 

-- 
regards,
-grygorii

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