[1/2] gpio: eic: Add edge trigger emulation for EIC

Message ID bdaaa8823cc3aef44352ee867fb6274278f2a2a9.1522392153.git.baolin.wang@linaro.org
State New
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Series
  • [1/2] gpio: eic: Add edge trigger emulation for EIC
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Commit Message

Baolin Wang March 30, 2018, 7:02 a.m.
The Spreadtrum debounce EIC and latch EIC can not support edge trigger,
but most GPIO users (like gpio-key driver) only use the edge trigger,
thus the EIC driver need add some support to emulate the edge trigger
to satisfy this requirement.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
---
 drivers/gpio/gpio-eic-sprd.c |   73 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)

Comments

Baolin Wang April 16, 2018, 8:18 a.m. | #1
Hi,

On 30 March 2018 at 15:02, Baolin Wang <baolin.wang@linaro.org> wrote:
> The Spreadtrum debounce EIC and latch EIC can not support edge trigger,
> but most GPIO users (like gpio-key driver) only use the edge trigger,
> thus the EIC driver need add some support to emulate the edge trigger
> to satisfy this requirement.
>
> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>

Any comments for this patch set? Thanks.

> ---
>  drivers/gpio/gpio-eic-sprd.c |   73 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 73 insertions(+)
>
> diff --git a/drivers/gpio/gpio-eic-sprd.c b/drivers/gpio/gpio-eic-sprd.c
> index de7dd93..e0d6a0a 100644
> --- a/drivers/gpio/gpio-eic-sprd.c
> +++ b/drivers/gpio/gpio-eic-sprd.c
> @@ -300,6 +300,7 @@ static int sprd_eic_irq_set_type(struct irq_data *data, unsigned int flow_type)
>         struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
>         struct sprd_eic *sprd_eic = gpiochip_get_data(chip);
>         u32 offset = irqd_to_hwirq(data);
> +       int state;
>
>         switch (sprd_eic->type) {
>         case SPRD_EIC_DEBOUNCE:
> @@ -310,6 +311,17 @@ static int sprd_eic_irq_set_type(struct irq_data *data, unsigned int flow_type)
>                 case IRQ_TYPE_LEVEL_LOW:
>                         sprd_eic_update(chip, offset, SPRD_EIC_DBNC_IEV, 0);
>                         break;
> +               case IRQ_TYPE_EDGE_RISING:
> +               case IRQ_TYPE_EDGE_FALLING:
> +               case IRQ_TYPE_EDGE_BOTH:
> +                       state = sprd_eic_get(chip, offset);
> +                       if (state)
> +                               sprd_eic_update(chip, offset,
> +                                               SPRD_EIC_DBNC_IEV, 0);
> +                       else
> +                               sprd_eic_update(chip, offset,
> +                                               SPRD_EIC_DBNC_IEV, 1);
> +                       break;
>                 default:
>                         return -ENOTSUPP;
>                 }
> @@ -324,6 +336,17 @@ static int sprd_eic_irq_set_type(struct irq_data *data, unsigned int flow_type)
>                 case IRQ_TYPE_LEVEL_LOW:
>                         sprd_eic_update(chip, offset, SPRD_EIC_LATCH_INTPOL, 1);
>                         break;
> +               case IRQ_TYPE_EDGE_RISING:
> +               case IRQ_TYPE_EDGE_FALLING:
> +               case IRQ_TYPE_EDGE_BOTH:
> +                       state = sprd_eic_get(chip, offset);
> +                       if (state)
> +                               sprd_eic_update(chip, offset,
> +                                               SPRD_EIC_LATCH_INTPOL, 0);
> +                       else
> +                               sprd_eic_update(chip, offset,
> +                                               SPRD_EIC_LATCH_INTPOL, 1);
> +                       break;
>                 default:
>                         return -ENOTSUPP;
>                 }
> @@ -405,6 +428,55 @@ static int sprd_eic_irq_set_type(struct irq_data *data, unsigned int flow_type)
>         return 0;
>  }
>
> +static void sprd_eic_toggle_trigger(struct gpio_chip *chip, unsigned int irq,
> +                                   unsigned int offset)
> +{
> +       struct sprd_eic *sprd_eic = gpiochip_get_data(chip);
> +       struct irq_data *data = irq_get_irq_data(irq);
> +       u32 trigger = irqd_get_trigger_type(data);
> +       int state, post_state;
> +
> +       /*
> +        * The debounce EIC and latch EIC can only support level trigger, so we
> +        * can toggle the level trigger to emulate the edge trigger.
> +        */
> +       if ((sprd_eic->type != SPRD_EIC_DEBOUNCE &&
> +            sprd_eic->type != SPRD_EIC_LATCH) ||
> +           !(trigger & IRQ_TYPE_EDGE_BOTH))
> +               return;
> +
> +       sprd_eic_irq_mask(data);
> +       state = sprd_eic_get(chip, offset);
> +
> +retry:
> +       switch (sprd_eic->type) {
> +       case SPRD_EIC_DEBOUNCE:
> +               if (state)
> +                       sprd_eic_update(chip, offset, SPRD_EIC_DBNC_IEV, 0);
> +               else
> +                       sprd_eic_update(chip, offset, SPRD_EIC_DBNC_IEV, 1);
> +               break;
> +       case SPRD_EIC_LATCH:
> +               if (state)
> +                       sprd_eic_update(chip, offset, SPRD_EIC_LATCH_INTPOL, 0);
> +               else
> +                       sprd_eic_update(chip, offset, SPRD_EIC_LATCH_INTPOL, 1);
> +               break;
> +       default:
> +               sprd_eic_irq_unmask(data);
> +               return;
> +       }
> +
> +       post_state = sprd_eic_get(chip, offset);
> +       if (state != post_state) {
> +               dev_warn(chip->parent, "EIC level was changed.\n");
> +               state = post_state;
> +               goto retry;
> +       }
> +
> +       sprd_eic_irq_unmask(data);
> +}
> +
>  static int sprd_eic_match_chip_by_type(struct gpio_chip *chip, void *data)
>  {
>         enum sprd_eic_type type = *(enum sprd_eic_type *)data;
> @@ -448,6 +520,7 @@ static void sprd_eic_handle_one_type(struct gpio_chip *chip)
>                                         bank * SPRD_EIC_PER_BANK_NR + n);
>
>                         generic_handle_irq(girq);
> +                       sprd_eic_toggle_trigger(chip, girq, n);
>                 }
>         }
>  }
> --
> 1.7.9.5
>
Linus Walleij April 26, 2018, 8:10 a.m. | #2
On Fri, Mar 30, 2018 at 9:02 AM, Baolin Wang <baolin.wang@linaro.org> wrote:

> The Spreadtrum debounce EIC and latch EIC can not support edge trigger,
> but most GPIO users (like gpio-key driver) only use the edge trigger,
> thus the EIC driver need add some support to emulate the edge trigger
> to satisfy this requirement.
>
> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>

Patch applied.

The patch is fine and in line with other kernel drivers doing edge
trigger emulation and we do not hold back on useful features.

But I want to take this opportunity to ping Uwe Kleine-König about
his ideas for an edge trigger emulation library in the gpiolib core,
and whether this also follows the pattern.

I think we have a slew of these drivers doing similar stuff around.

Yours,
Linus Walleij
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Uwe Kleine-König April 26, 2018, 8:29 a.m. | #3
Hello Linus,

On Thu, Apr 26, 2018 at 10:10:11AM +0200, Linus Walleij wrote:
> On Fri, Mar 30, 2018 at 9:02 AM, Baolin Wang <baolin.wang@linaro.org> wrote:
> 
> > The Spreadtrum debounce EIC and latch EIC can not support edge trigger,
> > but most GPIO users (like gpio-key driver) only use the edge trigger,
> > thus the EIC driver need add some support to emulate the edge trigger
> > to satisfy this requirement.
> >
> > Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
> 
> Patch applied.
> 
> The patch is fine and in line with other kernel drivers doing edge
> trigger emulation and we do not hold back on useful features.
> 
> But I want to take this opportunity to ping Uwe Kleine-König about
> his ideas for an edge trigger emulation library in the gpiolib core,
> and whether this also follows the pattern.

up to now it's still only this: an idea.

Best regards
Uwe

Patch

diff --git a/drivers/gpio/gpio-eic-sprd.c b/drivers/gpio/gpio-eic-sprd.c
index de7dd93..e0d6a0a 100644
--- a/drivers/gpio/gpio-eic-sprd.c
+++ b/drivers/gpio/gpio-eic-sprd.c
@@ -300,6 +300,7 @@  static int sprd_eic_irq_set_type(struct irq_data *data, unsigned int flow_type)
 	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
 	struct sprd_eic *sprd_eic = gpiochip_get_data(chip);
 	u32 offset = irqd_to_hwirq(data);
+	int state;
 
 	switch (sprd_eic->type) {
 	case SPRD_EIC_DEBOUNCE:
@@ -310,6 +311,17 @@  static int sprd_eic_irq_set_type(struct irq_data *data, unsigned int flow_type)
 		case IRQ_TYPE_LEVEL_LOW:
 			sprd_eic_update(chip, offset, SPRD_EIC_DBNC_IEV, 0);
 			break;
+		case IRQ_TYPE_EDGE_RISING:
+		case IRQ_TYPE_EDGE_FALLING:
+		case IRQ_TYPE_EDGE_BOTH:
+			state = sprd_eic_get(chip, offset);
+			if (state)
+				sprd_eic_update(chip, offset,
+						SPRD_EIC_DBNC_IEV, 0);
+			else
+				sprd_eic_update(chip, offset,
+						SPRD_EIC_DBNC_IEV, 1);
+			break;
 		default:
 			return -ENOTSUPP;
 		}
@@ -324,6 +336,17 @@  static int sprd_eic_irq_set_type(struct irq_data *data, unsigned int flow_type)
 		case IRQ_TYPE_LEVEL_LOW:
 			sprd_eic_update(chip, offset, SPRD_EIC_LATCH_INTPOL, 1);
 			break;
+		case IRQ_TYPE_EDGE_RISING:
+		case IRQ_TYPE_EDGE_FALLING:
+		case IRQ_TYPE_EDGE_BOTH:
+			state = sprd_eic_get(chip, offset);
+			if (state)
+				sprd_eic_update(chip, offset,
+						SPRD_EIC_LATCH_INTPOL, 0);
+			else
+				sprd_eic_update(chip, offset,
+						SPRD_EIC_LATCH_INTPOL, 1);
+			break;
 		default:
 			return -ENOTSUPP;
 		}
@@ -405,6 +428,55 @@  static int sprd_eic_irq_set_type(struct irq_data *data, unsigned int flow_type)
 	return 0;
 }
 
+static void sprd_eic_toggle_trigger(struct gpio_chip *chip, unsigned int irq,
+				    unsigned int offset)
+{
+	struct sprd_eic *sprd_eic = gpiochip_get_data(chip);
+	struct irq_data *data = irq_get_irq_data(irq);
+	u32 trigger = irqd_get_trigger_type(data);
+	int state, post_state;
+
+	/*
+	 * The debounce EIC and latch EIC can only support level trigger, so we
+	 * can toggle the level trigger to emulate the edge trigger.
+	 */
+	if ((sprd_eic->type != SPRD_EIC_DEBOUNCE &&
+	     sprd_eic->type != SPRD_EIC_LATCH) ||
+	    !(trigger & IRQ_TYPE_EDGE_BOTH))
+		return;
+
+	sprd_eic_irq_mask(data);
+	state = sprd_eic_get(chip, offset);
+
+retry:
+	switch (sprd_eic->type) {
+	case SPRD_EIC_DEBOUNCE:
+		if (state)
+			sprd_eic_update(chip, offset, SPRD_EIC_DBNC_IEV, 0);
+		else
+			sprd_eic_update(chip, offset, SPRD_EIC_DBNC_IEV, 1);
+		break;
+	case SPRD_EIC_LATCH:
+		if (state)
+			sprd_eic_update(chip, offset, SPRD_EIC_LATCH_INTPOL, 0);
+		else
+			sprd_eic_update(chip, offset, SPRD_EIC_LATCH_INTPOL, 1);
+		break;
+	default:
+		sprd_eic_irq_unmask(data);
+		return;
+	}
+
+	post_state = sprd_eic_get(chip, offset);
+	if (state != post_state) {
+		dev_warn(chip->parent, "EIC level was changed.\n");
+		state = post_state;
+		goto retry;
+	}
+
+	sprd_eic_irq_unmask(data);
+}
+
 static int sprd_eic_match_chip_by_type(struct gpio_chip *chip, void *data)
 {
 	enum sprd_eic_type type = *(enum sprd_eic_type *)data;
@@ -448,6 +520,7 @@  static void sprd_eic_handle_one_type(struct gpio_chip *chip)
 					bank * SPRD_EIC_PER_BANK_NR + n);
 
 			generic_handle_irq(girq);
+			sprd_eic_toggle_trigger(chip, girq, n);
 		}
 	}
 }