Re: [PATCH V1 10/12] gpio: tegra: implement wake event support for Tegra210 and prior GPIO

[Thierry Reding]

On Tue, May 21, 2019 at 04:31:21PM -0700, Sowjanya Komatineni wrote:
> The GPIO controller doesn't have any controls to enable the system to
> wake up from low power states based on activity on GPIO pins. An extra
> hardware block that is part of the power management controller (PMC)
> contains these controls. In order for the GPIO controller to be able
> to cooperate with the PMC, obtain a reference to the PMC's IRQ domain
> and make it a parent to the GPIO controller's IRQ domain. This way the
> PMC gets an opportunity to program the additional registers required
> to enable wakeup sources on suspend.
> 
> Signed-off-by: Sowjanya Komatineni <skomatineni@xxxxxxxxxx>
> ---
>  drivers/gpio/gpio-tegra.c | 109 +++++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 103 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpio/gpio-tegra.c b/drivers/gpio/gpio-tegra.c
> index 6d9b6906b9d0..d57e33050d0c 100644
> --- a/drivers/gpio/gpio-tegra.c
> +++ b/drivers/gpio/gpio-tegra.c
> @@ -32,6 +32,8 @@
>  #include <linux/pinctrl/consumer.h>
>  #include <linux/pm.h>
>  
> +#include <dt-bindings/interrupt-controller/arm-gic.h>
> +
>  #define GPIO_BANK(x)		((x) >> 5)
>  #define GPIO_PORT(x)		(((x) >> 3) & 0x3)
>  #define GPIO_BIT(x)		((x) & 0x7)
> @@ -275,8 +277,22 @@ static int tegra_gpio_set_config(struct gpio_chip *chip, unsigned int offset,
>  static int tegra_gpio_to_irq(struct gpio_chip *chip, unsigned int offset)
>  {
>  	struct tegra_gpio_info *tgi = gpiochip_get_data(chip);
> +	struct irq_domain *domain = tgi->irq_domain;
> +
> +	if (!gpiochip_irqchip_irq_valid(chip, offset))
> +		return -ENXIO;
> +
> +	if (irq_domain_is_hierarchy(domain)) {
> +		struct irq_fwspec spec;
> +
> +		spec.fwnode = domain->fwnode;
> +		spec.param_count = 2;
> +		spec.param[0] = offset;
> +		spec.param[1] = IRQ_TYPE_NONE;
> +		return irq_domain_alloc_irqs(domain, 1, NUMA_NO_NODE, &spec);
> +	}
>  
> -	return irq_find_mapping(tgi->irq_domain, offset);
> +	return irq_find_mapping(domain, offset);
>  }
>  
>  static void tegra_gpio_irq_ack(struct irq_data *d)
> @@ -365,7 +381,10 @@ static int tegra_gpio_irq_set_type(struct irq_data *d, unsigned int type)
>  	else if (type & (IRQ_TYPE_EDGE_FALLING | IRQ_TYPE_EDGE_RISING))
>  		irq_set_handler_locked(d, handle_edge_irq);
>  
> -	return 0;
> +	if (d->parent_data)
> +		return irq_chip_set_type_parent(d, type);
> +	else
> +		return 0;

Why is this needed?

>  }
>  
>  static void tegra_gpio_irq_shutdown(struct irq_data *d)
> @@ -566,10 +585,79 @@ static const struct dev_pm_ops tegra_gpio_pm_ops = {
>  	SET_SYSTEM_SLEEP_PM_OPS(tegra_gpio_suspend, tegra_gpio_resume)
>  };
>  
> +static int tegra_gpio_irq_domain_translate(struct irq_domain *domain,
> +					   struct irq_fwspec *fwspec,
> +					   unsigned long *hwirq,
> +					   unsigned int *type)
> +{
> +	if (WARN_ON(fwspec->param_count < 2))
> +		return -EINVAL;
> +
> +	*type = fwspec->param[1] & IRQ_TYPE_SENSE_MASK;
> +	*hwirq = fwspec->param[0];
> +
> +	return 0;
> +}
> +
> +static int tegra_gpio_irq_domain_alloc(struct irq_domain *domain,
> +				       unsigned int virq,
> +				       unsigned int num_irqs, void *data)
> +{
> +	struct tegra_gpio_info *tgi = gpiochip_get_data(domain->host_data);
> +	struct irq_fwspec *fwspec = data;
> +	struct irq_fwspec spec;

You can put the above two lines onto a single line.

> +	struct tegra_gpio_bank *bank;
> +	unsigned long hwirq;
> +	unsigned int type;
> +	int err = 0;
> +
> +	if (WARN_ON(fwspec->param_count < 2))
> +		return -EINVAL;
> +
> +	if (!irq_domain_get_of_node(domain->parent))
> +		return -EINVAL;

Can this ever fail?

> +
> +	err = tegra_gpio_irq_domain_translate(domain, fwspec, &hwirq, &type);
> +	if (err)
> +		return err;
> +
> +	bank = &tgi->bank_info[GPIO_BANK(hwirq)];
> +	err = irq_domain_set_hwirq_and_chip(domain, virq, hwirq,
> +					    &tgi->ic, bank);
> +
> +	if (err < 0)
> +		return err;
> +
> +	spec.fwnode = domain->parent->fwnode;
> +	spec.param_count = 3;
> +	spec.param[0] = GIC_SPI;
> +	spec.param[1] = fwspec->param[0];
> +	spec.param[2] = fwspec->param[1];
> +
> +	return irq_domain_alloc_irqs_parent(domain, virq, 1, &spec);

What if num_irqs is different from 1? I'm not exactly sure what to pass
as &spec, but likely we'd have to create an array of struct irq_fwspec
and pass that along. It seems like some drivers catch that case and
refuse to work rather than pass potentially rubbish information along.
See for example drivers/irqchip/irq-meson-gpio.c.

> +}
> +
> +static const struct irq_domain_ops tegra_gpio_irq_domain_ops = {
> +	.translate = tegra_gpio_irq_domain_translate,
> +	.alloc = tegra_gpio_irq_domain_alloc,
> +};
> +
> +static const struct of_device_id tegra_pmc_of_match[] = {
> +	{ .compatible = "nvidia,tegra210-pmc" },
> +	{ .compatible = "nvidia,tegra132-pmc" },
> +	{ .compatible = "nvidia,tegra124-pmc" },
> +	{ .compatible = "nvidia,tegra114-pmc" },
> +	{ .compatible = "nvidia,tegra30-pmc" },
> +	{ .compatible = "nvidia,tegra20-pmc" },
> +	{ }
> +};
> +
>  static int tegra_gpio_probe(struct platform_device *pdev)
>  {
>  	struct tegra_gpio_info *tgi;
>  	struct tegra_gpio_bank *bank;
> +	struct device_node *np;
> +	struct irq_domain *parent_domain = NULL;
>  	unsigned int gpio, i, j;
>  	int ret;
>  
> @@ -612,8 +700,15 @@ static int tegra_gpio_probe(struct platform_device *pdev)
>  	tgi->ic.irq_set_type		= tegra_gpio_irq_set_type;
>  	tgi->ic.irq_shutdown		= tegra_gpio_irq_shutdown;
>  #ifdef CONFIG_PM_SLEEP
> -	tgi->ic.irq_set_wake		= tegra_gpio_irq_set_wake;
> +	tgi->ic.irq_set_wake		= irq_chip_set_wake_parent;

This doesn't seem right. What about tegra_gpio_irq_set_wake()? If it's
no longer needed, just remove it. But then, what about the extra logic
in that function that causes the interrupts to be enabled during
suspend? Is that no longer necessary? Maybe that's no longer needed on
Tegra210, but what about other Tegra generations?

Thierry

>  #endif
> +	np = of_find_matching_node(NULL, tegra_pmc_of_match);
> +	if (np) {
> +		parent_domain = irq_find_host(np);
> +		of_node_put(np);
> +		if (!parent_domain)
> +			return -EPROBE_DEFER;
> +	}
>  
>  	platform_set_drvdata(pdev, tgi);
>  
> @@ -625,9 +720,11 @@ static int tegra_gpio_probe(struct platform_device *pdev)
>  	if (!tgi->bank_info)
>  		return -ENOMEM;
>  
> -	tgi->irq_domain = irq_domain_add_linear(pdev->dev.of_node,
> -						tgi->gc.ngpio,
> -						&irq_domain_simple_ops, NULL);
> +	tgi->irq_domain = irq_domain_add_hierarchy(parent_domain, 0,
> +						   tgi->gc.ngpio,
> +						   pdev->dev.of_node,
> +						   &tegra_gpio_irq_domain_ops,
> +						   &tgi->gc);
>  	if (!tgi->irq_domain)
>  		return -ENODEV;
>  
> -- 
> 2.7.4
>

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