linux-kernel - [PATCH 1/4] gpio: gpiolib: Allow GPIO IRQs to lazy disable

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Date:   Fri, 22 May 2020 18:49:26 +0530
From:   Maulik Shah <mkshah@...eaurora.org>
To:     bjorn.andersson@...aro.org, maz@...nel.org,
        linus.walleij@...aro.org, swboyd@...omium.org,
        evgreen@...omium.org, mka@...omium.org
Cc:     linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-gpio@...r.kernel.org, agross@...nel.org, tglx@...utronix.de,
        jason@...edaemon.net, dianders@...omium.org, rnayak@...eaurora.org,
        ilina@...eaurora.org, lsrao@...eaurora.org,
        Maulik Shah <mkshah@...eaurora.org>
Subject: [PATCH 1/4] gpio: gpiolib: Allow GPIO IRQs to lazy disable

With 'commit 461c1a7d4733 ("gpiolib: override irq_enable/disable")' gpiolib
overrides irqchip's irq_enable and irq_disable callbacks. If irq_disable
callback is implemented then genirq takes unlazy path to disable irq.

Underlying irqchip may not want to implement irq_disable callback to lazy
disable irq when client drivers invokes disable_irq(). By overriding
irq_disable callback, gpiolib ends up always unlazy disabling IRQ.

Allow gpiolib to lazy disable IRQs by overriding irq_disable callback only
if irqchip implemented irq_disable. In cases where irq_disable is not
implemented irq_mask is overridden. Similarly override irq_enable callback
only if irqchip implemented irq_enable otherwise irq_unmask is overridden.

Fixes: 461c1a7d47 (gpiolib: override irq_enable/disable)
Signed-off-by: Maulik Shah <mkshah@...eaurora.org>
---
 drivers/gpio/gpiolib.c      | 59 +++++++++++++++++++++++++++++----------------
 include/linux/gpio/driver.h | 13 ++++++++++
 2 files changed, 51 insertions(+), 21 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index eaa0e20..a8fdc74 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -2465,33 +2465,38 @@ static void gpiochip_irq_relres(struct irq_data *d)
 	gpiochip_relres_irq(gc, d->hwirq);
 }
 
+static void gpiochip_irq_mask(struct irq_data *d)
+{
+	struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
+
+	if (chip->irq.irq_mask)
+		chip->irq.irq_mask(d);
+	gpiochip_disable_irq(chip, d->hwirq);
+}
+
+static void gpiochip_irq_unmask(struct irq_data *d)
+{
+	struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
+
+	gpiochip_enable_irq(chip, d->hwirq);
+	if (chip->irq.irq_unmask)
+		chip->irq.irq_unmask(d);
+}
+
 static void gpiochip_irq_enable(struct irq_data *d)
 {
 	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
 
-	gpiochip_enable_irq(gc, d->hwirq);
-	if (gc->irq.irq_enable)
-		gc->irq.irq_enable(d);
-	else
-		gc->irq.chip->irq_unmask(d);
+	gpiochip_enable_irq(chip, d->hwirq);
+	chip->irq.irq_enable(d);
 }
 
 static void gpiochip_irq_disable(struct irq_data *d)
 {
 	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
 
-	/*
-	 * Since we override .irq_disable() we need to mimic the
-	 * behaviour of __irq_disable() in irq/chip.c.
-	 * First call .irq_disable() if it exists, else mimic the
-	 * behaviour of mask_irq() which calls .irq_mask() if
-	 * it exists.
-	 */
-	if (gc->irq.irq_disable)
-		gc->irq.irq_disable(d);
-	else if (gc->irq.chip->irq_mask)
-		gc->irq.chip->irq_mask(d);
-	gpiochip_disable_irq(gc, d->hwirq);
+	chip->irq.irq_disable(d);
+	gpiochip_disable_irq(chip, d->hwirq);
 }
 
 static void gpiochip_set_irq_hooks(struct gpio_chip *gc)
@@ -2515,10 +2520,22 @@ static void gpiochip_set_irq_hooks(struct gpio_chip *gc)
 			  "detected irqchip that is shared with multiple gpiochips: please fix the driver.\n");
 		return;
 	}
-	gc->irq.irq_enable = irqchip->irq_enable;
-	gc->irq.irq_disable = irqchip->irq_disable;
-	irqchip->irq_enable = gpiochip_irq_enable;
-	irqchip->irq_disable = gpiochip_irq_disable;
+
+	if (irqchip->irq_disable) {
+		gpiochip->irq.irq_disable = irqchip->irq_disable;
+		irqchip->irq_disable = gpiochip_irq_disable;
+	} else {
+		gpiochip->irq.irq_mask = irqchip->irq_mask;
+		irqchip->irq_mask = gpiochip_irq_mask;
+	}
+
+	if (irqchip->irq_enable) {
+		gpiochip->irq.irq_enable = irqchip->irq_enable;
+		irqchip->irq_enable = gpiochip_irq_enable;
+	} else {
+		gpiochip->irq.irq_unmask = irqchip->irq_unmask;
+		irqchip->irq_unmask = gpiochip_irq_unmask;
+	}
 }
 
 /**
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index 8c41ae4..c8bcaf3 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -253,6 +253,19 @@ struct gpio_irq_chip {
 	 * Store old irq_chip irq_disable callback
 	 */
 	void		(*irq_disable)(struct irq_data *data);
+	/**
+	 * @irq_unmask:
+	 *
+	 * Store old irq_chip irq_unmask callback
+	 */
+	void		(*irq_unmask)(struct irq_data *data);
+
+	/**
+	 * @irq_mask:
+	 *
+	 * Store old irq_chip irq_mask callback
+	 */
+	void		(*irq_mask)(struct irq_data *data);
 };
 
 /**
-- 
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