Message-ID: <20181009170701.GS11144@codeaurora.org>
Date:   Tue, 9 Oct 2018 11:07:01 -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

On Tue, Oct 02 2018 at 11:06 -0600, Lina Iyer wrote:
>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?
>
Would it help if I submit a RFC patch based on this idea?

>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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