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Date:   Fri, 21 Sep 2018 00:11:28 +0100
Message-ID: <86k1nfwyqn.wl-marc.zyngier@arm.com>
From:   Marc Zyngier <marc.zyngier@arm.com>
To:     Lina Iyer <ilina@codeaurora.org>
Cc:     bjorn.andersson@linaro.org, sboyd@kernel.org, evgreen@chromium.org,
        linus.walleij@linaro.org, rplsssn@codeaurora.org,
        linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        rnayak@codeaurora.org, devicetree@vger.kernel.org,
        andy.gross@linaro.org, dianders@chromium.org
Subject: Re: [PATCH v3 1/5] drivers: pinctrl: qcom: add wakeup capability to GPIO
In-Reply-To: <20180904211810.5506-2-ilina@codeaurora.org>
References: <20180904211810.5506-1-ilina@codeaurora.org>
        <20180904211810.5506-2-ilina@codeaurora.org>
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Hi Lina,

On Tue, 04 Sep 2018 22:18:06 +0100,
Lina Iyer <ilina@codeaurora.org> wrote:
> 
> QCOM SoC's that have Power Domain Controller (PDC) chip in the always-on
> domain can wakeup the SoC, when interrupts and GPIOs are routed to its
> interrupt controller. Only select GPIOs that are deemed wakeup capable
> are routed to specific PDC pins. During low power state, the pinmux
> interrupt controller may be non-functional but the PDC would be. The PDC
> can detect the wakeup GPIO is triggered and bring the TLMM to an
> operational state.
> 
> Interrupts that are level triggered will be detected at the TLMM when
> the controller becomes operational. Edge interrupts however need to be
> replayed again.
> 
> Request the corresponding PDC IRQ, when the GPIO is requested as an IRQ,
> but keep it disabled. During suspend, we can enable the PDC IRQ instead
> of the GPIO IRQ, which may or not be detected.
> 
> Signed-off-by: Lina Iyer <ilina@codeaurora.org>
> ---
> Changes in v3:
> 	- free action->name
> Changes in v2:
> 	- Remove IRQF_NO_SUSPEND and IRQF_ONE_SHOT from PDC IRQ
> Changes in v1:
> 	- Trigger GPIO in h/w from PDC IRQ handler
> 	- Avoid big tables for GPIO-PDC map, pick from DT instead
> 	- Use handler_data
> ---
>  drivers/pinctrl/qcom/pinctrl-msm.c | 98 ++++++++++++++++++++++++++++++
>  1 file changed, 98 insertions(+)
> 
> diff --git a/drivers/pinctrl/qcom/pinctrl-msm.c b/drivers/pinctrl/qcom/pinctrl-msm.c
> index 0e22f52b2a19..6527a0a9edd1 100644
> --- a/drivers/pinctrl/qcom/pinctrl-msm.c
> +++ b/drivers/pinctrl/qcom/pinctrl-msm.c
> @@ -687,11 +687,15 @@ static int msm_gpio_irq_set_type(struct irq_data *d, unsigned int type)
>  	const struct msm_pingroup *g;
>  	unsigned long flags;
>  	u32 val;
> +	struct irq_data *pdc_irqd = irq_get_handler_data(d->irq);
>  
>  	g = &pctrl->soc->groups[d->hwirq];
>  
>  	raw_spin_lock_irqsave(&pctrl->lock, flags);
>  
> +	if (pdc_irqd)
> +		irq_set_irq_type(pdc_irqd->irq, type);
> +
>  	/*
>  	 * For hw without possibility of detecting both edges
>  	 */
> @@ -779,9 +783,13 @@ static int msm_gpio_irq_set_wake(struct irq_data *d, unsigned int on)
>  	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
>  	struct msm_pinctrl *pctrl = gpiochip_get_data(gc);
>  	unsigned long flags;
> +	struct irq_data *pdc_irqd = irq_get_handler_data(d->irq);
>  
>  	raw_spin_lock_irqsave(&pctrl->lock, flags);
>  
> +	if (pdc_irqd)
> +		irq_set_irq_wake(pdc_irqd->irq, on);
> +
>  	irq_set_irq_wake(pctrl->irq, on);
>  
>  	raw_spin_unlock_irqrestore(&pctrl->lock, flags);
> @@ -863,6 +871,94 @@ static bool msm_gpio_needs_valid_mask(struct msm_pinctrl *pctrl)
>  	return device_property_read_u16_array(pctrl->dev, "gpios", NULL, 0) > 0;
>  }
>  
> +static irqreturn_t wake_irq_gpio_handler(int irq, void *data)
> +{
> +	struct irq_data *irqd = data;
> +	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
> +	struct msm_pinctrl *pctrl = gpiochip_get_data(gc);
> +	const struct msm_pingroup *g;
> +	unsigned long flags;
> +	u32 val;
> +
> +	if (!irqd_is_level_type(irqd)) {
> +		g = &pctrl->soc->groups[irqd->hwirq];
> +		raw_spin_lock_irqsave(&pctrl->lock, flags);
> +		val = BIT(g->intr_status_bit);
> +		writel(val, pctrl->regs + g->intr_status_reg);

write_relaxed, please.

> +		raw_spin_unlock_irqrestore(&pctrl->lock, flags);
> +	}

Overall, this requires some form of documentation (I'll have forgotten
about the whole thing quickly enough).

> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int msm_gpio_pdc_pin_request(struct irq_data *d)
> +{
> +	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
> +	struct msm_pinctrl *pctrl = gpiochip_get_data(gc);
> +	struct platform_device *pdev = to_platform_device(pctrl->dev);
> +	const char *pin_name;
> +	int irq;
> +	int ret;
> +
> +	pin_name = kasprintf(GFP_KERNEL, "gpio%lu", d->hwirq);
> +	if (!pin_name)
> +		return -ENOMEM;
> +
> +	irq = platform_get_irq_byname(pdev, pin_name);
> +	if (irq < 0) {
> +		kfree(pin_name);
> +		return 0;
> +	}
> +
> +	ret = request_irq(irq, wake_irq_gpio_handler, irqd_get_trigger_type(d),
> +			  pin_name, d);
> +	if (ret) {
> +		pr_warn("GPIO-%lu could not be set up as wakeup", d->hwirq);

This message doesn't correspond to what you're doing here.

> +		kfree(pin_name);
> +		return ret;
> +	}
> +
> +	irq_set_handler_data(d->irq, irq_get_irq_data(irq));
> +	disable_irq(irq);

Who enables this interrupt?

There is a gap between request_irq and disable_irq, where you can take
the interrupt, and not having set the handler data. Horrible things
will happen in this situation.

A slightly better way of doing that would be:

	// Prevent the interrupt from being enabled on request
	irq_set_status_flags(d->irq, IRQ_NOAUTOEN);
	ret = request_irq(...);
	irq_set_handler(...);

and let the enable_irq() do its thing when it happens (where?).

> +
> +	return 0;
> +}
> +
> +static int msm_gpio_pdc_pin_release(struct irq_data *d)
> +{
> +	struct irq_data *pdc_irqd = irq_get_handler_data(d->irq);
> +	const void *name;
> +
> +	if (pdc_irqd) {
> +		irq_set_handler_data(d->irq, NULL);
> +		name = free_irq(pdc_irqd->irq, d);
> +		kfree(name);
> +	}
> +
> +	return 0;
> +}
> +
> +static int msm_gpio_irq_reqres(struct irq_data *d)
> +{
> +	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
> +
> +	if (gpiochip_lock_as_irq(gc, irqd_to_hwirq(d))) {
> +		dev_err(gc->parent, "unable to lock HW IRQ %lu for IRQ\n",
> +			irqd_to_hwirq(d));
> +		return -EINVAL;
> +	}
> +
> +	return msm_gpio_pdc_pin_request(d);
> +}
> +
> +static void msm_gpio_irq_relres(struct irq_data *d)
> +{
> +	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
> +
> +	msm_gpio_pdc_pin_release(d);
> +	gpiochip_unlock_as_irq(gc, irqd_to_hwirq(d));
> +}
> +
>  static int msm_gpio_init(struct msm_pinctrl *pctrl)
>  {
>  	struct gpio_chip *chip;
> @@ -887,6 +983,8 @@ static int msm_gpio_init(struct msm_pinctrl *pctrl)
>  	pctrl->irq_chip.irq_ack = msm_gpio_irq_ack;
>  	pctrl->irq_chip.irq_set_type = msm_gpio_irq_set_type;
>  	pctrl->irq_chip.irq_set_wake = msm_gpio_irq_set_wake;
> +	pctrl->irq_chip.irq_request_resources = msm_gpio_irq_reqres;
> +	pctrl->irq_chip.irq_release_resources = msm_gpio_irq_relres;
>  
>  	ret = gpiochip_add_data(&pctrl->chip, pctrl);
>  	if (ret) {
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
> 

Thanks,

	M.

-- 
Jazz is not dead, it just smell funny.