Re: [PATCH RfC v4 5/6] pinctrl: meson: add support for GPIO interrupts

[Jerome Brunet <jbrunet@baylibre.com>]

On Mon, 2017-05-29 at 22:12 +0200, Heiner Kallweit wrote:
> Am 29.05.2017 um 10:43 schrieb Neil Armstrong:
> > Hi Heiner,
> > 
> > On 05/28/2017 09:12 PM, 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@gmail.com>
> > > ---
> > >  drivers/pinctrl/Kconfig               |   2 +
> > >  drivers/pinctrl/meson/pinctrl-meson.c | 164
> > > +++++++++++++++++++++++++++++++++-
> > >  2 files changed, 165 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/pinctrl/Kconfig b/drivers/pinctrl/Kconfig
> > > index abc1cef7..d8c92809 100644
> > > --- a/drivers/pinctrl/Kconfig
> > > +++ b/drivers/pinctrl/Kconfig
> > > @@ -166,8 +166,10 @@ config PINCTRL_MESON
> > >  	select PINCONF
> > >  	select GENERIC_PINCONF
> > >  	select GPIOLIB
> > > +	select GPIOLIB_IRQCHIP
> > >  	select OF_GPIO
> > >  	select REGMAP_MMIO
> > > +	select MESON_GPIO_INTC
> > 
> > This should not be here, there is not "compile-time" dependency.
> > 
> > >  
> > >  config PINCTRL_OXNAS
> > >  	bool
> > > diff --git a/drivers/pinctrl/meson/pinctrl-meson.c
> > > b/drivers/pinctrl/meson/pinctrl-meson.c
> > > index 66ed70c1..7fb98c71 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 +499,150 @@ 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;
> > > +
> > > +	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);
> > > +	}
> > 
> > Same as irqchip, please add paragraph explaining why you use *2 here to
> > handle the
> > IRQ_BOTH situation.
> > 
> > > +}
> > > +
> > > +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;
> > > +
> > > +	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;
> > > +
> > > +        /*
> > 
> > Please correct indentation.
> > 
> > > +	 * Add one bit to hwirq to allow for
> > > +	 * - using the same gpio hwirq twice
> > > +	 * - decoding the gpio hwirq in the interrupt controller driver
> > > +         */
> > > +	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;
> > > +}
> > 
> > You will have an irq leak if you chance twice of type in the same GPIO from
> > BOTH to Edge/Level.
> > 
> 
> I'm not sure I get your point.
> This function is called once for a GPIO IRQ, typically within request_irq()
> based on the type flags (provided that gpio_to_irq is used).
> And I don't change the type from BOTH to something, I create two parent irq's
> with type RISING/FALLING.

Is there anything preventing the consumer driver from calling "irq_set_irq_type"
 on its irq ? 

By the way, I wonder if "irq_set_irq_type" is supposed to be fast (callable from
an irq handler). In such case, irq_create_fwspec_mapping cannot be called from
.irq_set_type (same as gpio_to_irq)

Again, I think this is a SW hack to compensate for a missing HW feature. I'm
curious to get the point of view the irq maintainers on it.

> 
> > > +
> > > +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 +704,8 @@ 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 +784,21 @@ static int meson_pinctrl_parse_dt(struct
> > > meson_pinctrl *pc,
> > >  		return PTR_ERR(pc->reg_gpio);
> > >  	}
> > >  
> > > +	if (!meson_pinctrl_irq_domain) {
> > > +		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);
> > > +	}
> > 
> > Please add some blank lines between logical sections of the code.
> > 
> > > +
> > >  	return 0;
> > >  }
> > >  
> > > 
> > 
> > Thanks,
> > Neil
> > 
> 
>