Commit dc749a09 authored Jul 21, 2017 by Grygorii Strashko Committed by Linus Walleij Aug 14, 2017

gpiolib: allow gpio irqchip to map irqs dynamically

Now IRQ mappings are always created for all (allowed) GPIOs in gpiochip in
gpiochip_irqchip_add_key() which goes against the idea of SPARSE_IRQ and,
as result, leads to:
 - increasing of memory consumption for IRQ descriptors most of which will
never ever be used (espessially on platform with a high number of GPIOs).
(sizeof(struct irq_desc) == 256 on my tested platforms)
 - imposibility to use GPIO irqchip APIs by gpio drivers when HW implements
GPIO IRQ functionality as IRQ crossbar/router which has only limited
number of IRQ outputs (example from [1], all GPIOs can be mapped on only 8
IRQs).

Hence, remove static IRQ mapping code from gpiochip_irqchip_add_key() and
instead replace irq_find_mapping() with irq_create_mapping() in
gpiochip_to_irq(). Also add additional gpiochip_irqchip_irq_valid() calls
in gpiochip_to_irq() and gpiochip_irq_map().

After this change gpio2irq mapping will happen the following way when GPIO
irqchip APIs are used by gpio driver:
 - IRQ mappings will be created statically if driver passes first_irq>0
vlaue in gpiochip_irqchip_add_key().
 - IRQ mappings will be created dynamically from gpio_to_irq() or
of_irq_get().

Tested on am335x-evm and dra72-evm-revc.
- dra72-evm-revc: number of created irq mappings decreased from 402 -> 135
  Mem savings 267*256 = 68352 (66kB)
- am335x-evm: number of created irq mappings decreased from 188 -> 63
  Mem savings 125*256 = 32000 (31kB)

[1] https://lkml.org/lkml/2017/6/15/428



Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

parent 108d23e3

drivers/gpio/gpiolib.c

+6 −23

Original line number	Diff line number	Diff line
		@@ -1615,6 +1615,9 @@ static int gpiochip_irq_map(struct irq_domain *d, unsigned int irq,
		{
		struct gpio_chip *chip = d->host_data;

		if (!gpiochip_irqchip_irq_valid(chip, hwirq))
		return -ENXIO;

		irq_set_chip_data(irq, chip);
		/*
		* This lock class tells lockdep that GPIO irqs are in a different
		@@ -1681,7 +1684,9 @@ static void gpiochip_irq_relres(struct irq_data *d)

		static int gpiochip_to_irq(struct gpio_chip *chip, unsigned offset)
		{
		return irq_find_mapping(chip->irqdomain, offset);
		if (!gpiochip_irqchip_irq_valid(chip, offset))
		return -ENXIO;
		return irq_create_mapping(chip->irqdomain, offset);
		}

		/**
		@@ -1757,9 +1762,6 @@ int gpiochip_irqchip_add_key(struct gpio_chip *gpiochip,
		struct lock_class_key *lock_key)
		{
		struct device_node *of_node;
		bool irq_base_set = false;
		unsigned int offset;
		unsigned irq_base = 0;

		if (!gpiochip \|\| !irqchip)
		return -EINVAL;
		@@ -1816,25 +1818,6 @@ int gpiochip_irqchip_add_key(struct gpio_chip *gpiochip,
		irqchip->irq_release_resources = gpiochip_irq_relres;
		}

		/*
		* Prepare the mapping since the irqchip shall be orthogonal to
		* any gpiochip calls. If the first_irq was zero, this is
		* necessary to allocate descriptors for all IRQs.
		*/
		for (offset = 0; offset < gpiochip->ngpio; offset++) {
		if (!gpiochip_irqchip_irq_valid(gpiochip, offset))
		continue;
		irq_base = irq_create_mapping(gpiochip->irqdomain, offset);
		if (!irq_base_set) {
		/*
		* Store the base into the gpiochip to be used when
		* unmapping the irqs.
		*/
		gpiochip->irq_base = irq_base;
		irq_base_set = true;
		}
		}

		acpi_gpiochip_request_interrupts(gpiochip);

		return 0;