2019-10-11 01:10:26

by Hui Song

Subject: [PATCH v8] gpio/mpc8xxx: change irq handler from chained to normal

From: Song Hui <[email protected]>

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 <[email protected]>
Signed-off-by: Alex Marginean <[email protected]>
Signed-off-by: Song Hui <[email protected]>
---
Changes in v8:
- merge two lines as one line to fit 80 characters.
Changes in v7:
- make unsigned int convert to unsigned long.
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 | 30 +++++++++++++++++++-----------
1 file changed, 19 insertions(+), 11 deletions(-)

diff --git a/drivers/gpio/gpio-mpc8xxx.c b/drivers/gpio/gpio-mpc8xxx.c
index 16a47de..58ff372 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 +128,19 @@ 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;
+ unsigned long mask;
+ int i;

mask = gc->read_reg(mpc8xxx_gc->regs + GPIO_IER)
& gc->read_reg(mpc8xxx_gc->regs + GPIO_IMR);
- if (mask)
- generic_handle_irq(irq_linear_revmap(mpc8xxx_gc->irq,
- 32 - ffs(mask)));
- if (chip->irq_eoi)
- chip->irq_eoi(&desc->irq_data);
+ for_each_set_bit(i, &mask, 32)
+ generic_handle_irq(irq_linear_revmap(mpc8xxx_gc->irq, 31 - i));
+
+ return IRQ_HANDLED;
}

static void mpc8xxx_irq_unmask(struct irq_data *d)
@@ -409,8 +409,16 @@ 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

2019-10-16 15:17:19

by Linus Walleij

Subject: Re: [PATCH v8] gpio/mpc8xxx: change irq handler from chained to normal

On Fri, Oct 11, 2019 at 3:07 AM Hui Song <[email protected]> wrote:

> 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 <[email protected]>
> Signed-off-by: Alex Marginean <[email protected]>
> Signed-off-by: Song Hui <[email protected]>
> ---
> Changes in v8:
> - merge two lines as one line to fit 80 characters.

Patch applied.

Yours,
Linus Walleij