Re: [PATCH v6 6/9] pinctrl: meson: add support for GPIO interrupts

[Jerome Brunet <jbrunet@xxxxxxxxxxxx>]

On Thu, 2017-06-08 at 21:39 +0200, Heiner Kallweit wrote:
> Add support for GPIO interrupts and make use of the just introduced
> irqchip driver handling the GPIO interrupt-controller.
> 
> Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
> ---
> v5:
> - changed Kconfig entry based on Neil's suggestion
> - extended comments
> - fixed indentation
> v6:
> - no changes
> ---
>  drivers/pinctrl/Kconfig               |   1 +
>  drivers/pinctrl/meson/pinctrl-meson.c | 170
> +++++++++++++++++++++++++++++++++-
>  2 files changed, 170 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pinctrl/Kconfig b/drivers/pinctrl/Kconfig
> index 7ae04a97..86834dea 100644
> --- a/drivers/pinctrl/Kconfig
> +++ b/drivers/pinctrl/Kconfig
> @@ -166,6 +166,7 @@ config PINCTRL_MESON
>  	select PINCONF
>  	select GENERIC_PINCONF
>  	select GPIOLIB
> +	select GPIOLIB_IRQCHIP
>  	select OF_GPIO
>  	select REGMAP_MMIO
>  
> diff --git a/drivers/pinctrl/meson/pinctrl-meson.c
> b/drivers/pinctrl/meson/pinctrl-meson.c
> index 66ed70c1..7bacd4e3 100644
> --- a/drivers/pinctrl/meson/pinctrl-meson.c
> +++ b/drivers/pinctrl/meson/pinctrl-meson.c
> @@ -62,6 +62,8 @@
>  #include "../pinctrl-utils.h"
>  #include "pinctrl-meson.h"
>  
> +static struct irq_domain *meson_pinctrl_irq_domain;
> +
>  /**
>   * meson_get_bank() - find the bank containing a given pin
>   *
> @@ -497,6 +499,154 @@ static int meson_gpio_get(struct gpio_chip *chip,
> unsigned gpio)
>  	return !!(val & BIT(bit));
>  }
>  
> +static struct meson_pinctrl *meson_gpio_data_to_pc(struct irq_data *data)
> +{
> +        struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
> +
> +        return gpiochip_get_data(chip);
> +}
> +
> +static int meson_gpio_bank_hwirq(struct meson_bank *bank, unsigned int
> offset)
> +{
> +        int hwirq;
> +
> +        if (bank->irq_first < 0)
> +                /* this bank cannot generate irqs */
> +                return 0;
> +
> +        hwirq = offset - bank->first + bank->irq_first;
> +
> +        if (hwirq > bank->irq_last)
> +                /* this pin cannot generate irqs */
> +                return 0;
> +
> +        return hwirq;
> +}
> +
> +static int meson_gpio_to_hwirq(struct irq_data *data)
> +{
> +	struct meson_pinctrl *pc = meson_gpio_data_to_pc(data);
> +	unsigned int offset = data->hwirq;
> +        struct meson_bank *bank;
> +        int hwirq, ret;
> +
> +        offset += pc->data->pin_base;
> +
> +        ret = meson_get_bank(pc, offset, &bank);
> +        if (ret)
> +                return ret;
> +
> +        hwirq = meson_gpio_bank_hwirq(bank, offset);
> +        if (!hwirq)
> +                dev_dbg(pc->dev, "no interrupt for pin %u\n", offset);
> +
> +        return hwirq;
> +}
> +
> +static void meson_gpio_irq_handler(struct irq_desc *desc)
> +{
> +        struct irq_chip *chip = irq_desc_get_chip(desc);
> +        struct irq_data *gpio_irq_data = irq_desc_get_handler_data(desc);
> +
> +        chained_irq_enter(chip, desc);
> +
> +        if (gpio_irq_data)
> +                generic_handle_irq(gpio_irq_data->irq);
> +
> +        chained_irq_exit(chip, desc);
> +}
> +
> +static void meson_gpio_irq_unmask(struct irq_data *data) {}
> +static void meson_gpio_irq_mask(struct irq_data *data) {}
> +
> +static void meson_gpio_irq_shutdown(struct irq_data *data)
> +{
> +	int hwirq = meson_gpio_to_hwirq(data);
> +	int irq;
> +
> +	if (hwirq <= 0)
> +		return;
> +
> +	/*
> +	 * In case of IRQ_TYPE_EDGE_BOTH we need two parent interrupts,
> +	 * one for each edge. That's due to HW constraints.
> +	 * We use format 2 * GPIO_HWIRQ +(0|1) for the hwirq, so we can
> +	 * have one GPIO_HWIRQ twice and derive the GPIO_HWIRQ from hwirq
> +	 * by shifting hwirq one bit to the right.
> +	 */
> +	irq = irq_find_mapping(meson_pinctrl_irq_domain, hwirq * 2);
> +	if (irq) {
> +		irq_set_chained_handler_and_data(irq, handle_bad_irq, NULL);
> +		irq_domain_free_irqs(irq, 1);
> +	}
> +
> +	irq = irq_find_mapping(meson_pinctrl_irq_domain, hwirq * 2 + 1);
> +	if (irq) {
> +		irq_set_chained_handler_and_data(irq, handle_bad_irq, NULL);
> +		irq_domain_free_irqs(irq, 1);
> +	}
> +}
> +
> +static int meson_gpio_irq_set_type(struct irq_data *data, unsigned int type)
> +{
> +	int hwirq = meson_gpio_to_hwirq(data);
> +	struct irq_fwspec fwspec;
> +        int irq, irq2, num_slots;
> +
> +	if (irqd_is_activated(data))
> +		return -EBUSY;

Again, your implementation assume that:
* irq_set_type should be called only once in the life of the irq.
* and/or irq_set_type cannot be called from irq context

I don't agree with those assumptions.
If irq_set_type could not called several times, to change the type at runtime,
why would the irq framework bother providing "irq_set_irq_type" in the public
API ? Why bother with irq_set_type callback at all ? It could all be done in the
startup callback... 


> +
> +	if (hwirq < 0)
> +		return hwirq;
> +
> +	if (!hwirq)
> +		return -ENXIO;
> +
> +	fwspec.fwnode = meson_pinctrl_irq_domain->fwnode;
> +	fwspec.param_count = 2;
> +
> +	/*
> +	 * The chip can create an interrupt for either rising or falling edge
> +	 * only. Therefore use two interrupts in case of IRQ_TYPE_EDGE_BOTH,
> +	 * first for falling edge and second one for rising edge.
> +	 */
> +	num_slots = (type == IRQ_TYPE_EDGE_BOTH) ? 2 : 1;
> +
> +	/* see comment in meson_gpio_irq_shutdown why we shift one bit here
> */
> +	fwspec.param[0] = hwirq << 1;
> +	if (num_slots == 1)
> +		fwspec.param[1] = type;
> +	else
> +		fwspec.param[1] = IRQ_TYPE_EDGE_FALLING;
> +
> +	irq = irq_create_fwspec_mapping(&fwspec);
> +	if (!irq)
> +		return -EINVAL;
> +
> +	irq_set_chained_handler_and_data(irq, meson_gpio_irq_handler, data);
> +
> +	if (num_slots > 1) {
> +		fwspec.param[0]++;
> +		fwspec.param[1] = IRQ_TYPE_EDGE_RISING;
> +		irq2 = irq_create_fwspec_mapping(&fwspec);
> +		if (!irq2) {
> +			irq_domain_free_irqs(irq, 1);
> +			return -EINVAL;
> +		}
> +		irq_set_chained_handler_and_data(irq2,
> meson_gpio_irq_handler, data);
> +	}
> +
> +        return 0;
> +}
> +
> +static struct irq_chip meson_gpio_irq_chip = {
> +        .name = "GPIO",
> +        .irq_set_type = meson_gpio_irq_set_type,
> +        .irq_mask = meson_gpio_irq_mask,
> +        .irq_unmask = meson_gpio_irq_unmask,
> +        .irq_shutdown = meson_gpio_irq_shutdown,
> +};
> +
>  static const struct of_device_id meson_pinctrl_dt_match[] = {
>  	{
>  		.compatible = "amlogic,meson8-cbus-pinctrl",
> @@ -558,7 +708,8 @@ static int meson_gpiolib_register(struct meson_pinctrl
> *pc)
>  		return ret;
>  	}
>  
> -	return 0;
> +	return gpiochip_irqchip_add(&pc->chip, &meson_gpio_irq_chip, 0,
> +				    handle_simple_irq, IRQ_TYPE_NONE);
>  }
>  
>  static struct regmap_config meson_regmap_config = {
> @@ -637,6 +788,23 @@ static int meson_pinctrl_parse_dt(struct meson_pinctrl
> *pc,
>  		return PTR_ERR(pc->reg_gpio);
>  	}
>  
> +	if (!meson_pinctrl_irq_domain) {

This be in " struct meson_pinctrl *pc" not a global.
Each instance should parse its own bindings and not rely on the other one for
this !

> +		np = of_find_compatible_node(NULL, NULL, "amlogic,meson-gpio-
> intc");
> +		if (!np) {
> +			dev_err(pc->dev, "interrupt controller DT node not
> found\n");
> +			return -EINVAL;
> +		}
> +
> +		meson_pinctrl_irq_domain = irq_find_host(np);
> +		if (!meson_pinctrl_irq_domain) {
> +			dev_err(pc->dev, "interrupt controller not found\n");
> +			of_node_put(np);
> +			return -EINVAL;
> +		}
> +
> +		of_node_put(np);
> +	}
> +
>  	return 0;
>  }
>  

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