Date:   Tue, 2 Oct 2018 11:06:22 -0600
From:   Lina Iyer <ilina@...eaurora.org>
To:     marc.zyngier@....com, bjorn.andersson@...aro.org, sboyd@...nel.org,
        evgreen@...omium.org, linus.walleij@...aro.org
Cc:     rplsssn@...eaurora.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, rnayak@...eaurora.org,
        devicetree@...r.kernel.org, andy.gross@...aro.org,
        dianders@...omium.org
Subject: Re: [PATCH v3 1/5] drivers: pinctrl: qcom: add wakeup capability to
 GPIO

Marc,

I am exploring an option where we don't do this enable/disable every
suspend/resume and in that process, I was able to just use the PDC
interrupt instead of the TLMM for triggering the GPIO. The PDC interrupt
(which takes over for the GPIO) has an handler like this -

On Tue, Sep 04 2018 at 15:18 -0600, Lina Iyer 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@...eaurora.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);
>+
I skip over the TLMM configuration for the GPIO interrupt and just set
the IRQ handler for the GPIO interrupt here..

> 	/*
> 	 * 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);
>+		raw_spin_unlock_irqrestore(&pctrl->lock, flags);
>+	}
>+
>+	return IRQ_HANDLED;
>+}
>+

Then ...

static irqreturn_t wake_irq_gpio_handler(int irq, void *data)
{
       struct irq_data *irqd = data;
       struct irq_desc *desc = irq_to_desc(irqd->irq);

       desc->handle_irq(desc);

       return IRQ_HANDLED;
}

I am following check_irq_resend() but I need to call the handler for
both level and edge interrupts. Firstly, is it okay to call the
handler_irq() directly?

My other question is check_irq_resend() indicates that it should be
called with desc->lock held. Since we are invoking the handler directly
and not modifying any core state of the irq_desc, is it safe here? (Also
the locking API are not exposed, I am sure there must be a reason for it).

Thoughts?

Thanks,
Lina

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

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