linux-kernel - [PATCH v6] gpio/mpc8xxx: change irq handler from chained to normal

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Message-Id: <20190927031551.20074-1-hui.song_1@nxp.com>
Date:   Fri, 27 Sep 2019 11:15:51 +0800
From:   Hui Song <hui.song_1@....com>
To:     Shawn Guo <shawnguo@...nel.org>, Li Yang <leoyang.li@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Cc:     linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
        Song Hui <hui.song_1@....com>
Subject: [PATCH v6] gpio/mpc8xxx: change irq handler from chained to normal

From: Song Hui <hui.song_1@....com>

More than one gpio controllers can share one interrupt, change the
driver to request shared irq.

While this will work, it will mess up userspace accounting of the number
of interrupts per second in tools such as vmstat.  The reason is that
for every GPIO interrupt, /proc/interrupts records the count against GIC
interrupt 68 or 69, as well as the GPIO itself.  So, for every GPIO
interrupt, the total number of interrupts that the system has seen
increments by two

Signed-off-by: Laurentiu Tudor <Laurentiu.Tudor@....com>
Signed-off-by: Alex Marginean <alexandru.marginean@....com>
Signed-off-by: Song Hui <hui.song_1@....com>
---
 Changes in v6:
	- change request_irq to devm_request_irq and add commit message
 Changes in v5:
	- add traverse every bit function.
 Changes in v4:
	- convert 'pr_err' to 'dev_err'.
 Changes in v3:
	- update the patch description.
 Changes in v2:
	- delete the compatible of ls1088a.

 drivers/gpio/gpio-mpc8xxx.c | 31 ++++++++++++++++++++-----------
 1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/drivers/gpio/gpio-mpc8xxx.c b/drivers/gpio/gpio-mpc8xxx.c
index 16a47de..f0be284 100644
--- a/drivers/gpio/gpio-mpc8xxx.c
+++ b/drivers/gpio/gpio-mpc8xxx.c
@@ -22,6 +22,7 @@
 #include <linux/irq.h>
 #include <linux/gpio/driver.h>
 #include <linux/bitops.h>
+#include <linux/interrupt.h>
 
 #define MPC8XXX_GPIO_PINS	32
 
@@ -127,20 +128,20 @@ static int mpc8xxx_gpio_to_irq(struct gpio_chip *gc, unsigned offset)
 		return -ENXIO;
 }
 
-static void mpc8xxx_gpio_irq_cascade(struct irq_desc *desc)
+static irqreturn_t mpc8xxx_gpio_irq_cascade(int irq, void *data)
 {
-	struct mpc8xxx_gpio_chip *mpc8xxx_gc = irq_desc_get_handler_data(desc);
-	struct irq_chip *chip = irq_desc_get_chip(desc);
+	struct mpc8xxx_gpio_chip *mpc8xxx_gc = data;
 	struct gpio_chip *gc = &mpc8xxx_gc->gc;
 	unsigned int mask;
+	int i;
 
 	mask = gc->read_reg(mpc8xxx_gc->regs + GPIO_IER)
 		& gc->read_reg(mpc8xxx_gc->regs + GPIO_IMR);
-	if (mask)
+	for_each_set_bit(i, &mask, 32)
 		generic_handle_irq(irq_linear_revmap(mpc8xxx_gc->irq,
-						     32 - ffs(mask)));
-	if (chip->irq_eoi)
-		chip->irq_eoi(&desc->irq_data);
+						     31 - i));
+
+	return IRQ_HANDLED;
 }
 
 static void mpc8xxx_irq_unmask(struct irq_data *d)
@@ -388,8 +389,8 @@ static int mpc8xxx_probe(struct platform_device *pdev)
 
 	ret = gpiochip_add_data(gc, mpc8xxx_gc);
 	if (ret) {
-		pr_err("%pOF: GPIO chip registration failed with status %d\n",
-		       np, ret);
+		dev_err(&pdev->dev, "%pOF: GPIO chip registration failed with status %d\n",
+			np, ret);
 		goto err;
 	}
 
@@ -409,8 +410,16 @@ static int mpc8xxx_probe(struct platform_device *pdev)
 	if (devtype->gpio_dir_in_init)
 		devtype->gpio_dir_in_init(gc);
 
-	irq_set_chained_handler_and_data(mpc8xxx_gc->irqn,
-					 mpc8xxx_gpio_irq_cascade, mpc8xxx_gc);
+	ret = devm_request_irq(&pdev->dev, mpc8xxx_gc->irqn,
+			       mpc8xxx_gpio_irq_cascade,
+			       IRQF_NO_THREAD | IRQF_SHARED, "gpio-cascade",
+			       mpc8xxx_gc);
+	if (ret) {
+		dev_err(&pdev->dev, "%s: failed to devm_request_irq(%d), ret = %d\n",
+			np->full_name, mpc8xxx_gc->irqn, ret);
+		goto err;
+	}
+
 	return 0;
 err:
 	iounmap(mpc8xxx_gc->regs);
-- 
2.9.5