gpio: eic: Add edge trigger emulation for EIC

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>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/drivers/gpio/gpio-eic-sprd.c b/drivers/gpio/gpio-eic-sprd.c
index de7dd93..e0d6a0a 100644 (file)
--- 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);
                }
        }
 }